From ab20efcfec9b9ba72a734c235510aca4d37a10fd Mon Sep 17 00:00:00 2001 From: Anders Svensson Date: Sat, 2 Sep 2017 12:34:37 +0200 Subject: Fix dictionary compilation error message Adding a second {Vendor-Id} to the common CER definition results in this error: ** AVP CER at line 85 already referenced at line 84 That is, the error incorrectly refers to the message name (CER) where the AVP name (Vendor-Id) is expected. --- lib/diameter/src/compiler/diameter_dict_util.erl | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/diameter/src/compiler/diameter_dict_util.erl b/lib/diameter/src/compiler/diameter_dict_util.erl index f9f2b02e94..7b53e51cb6 100644 --- a/lib/diameter/src/compiler/diameter_dict_util.erl +++ b/lib/diameter/src/compiler/diameter_dict_util.erl @@ -1,7 +1,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 2010-2016. All Rights Reserved. +%% Copyright Ericsson AB 2010-2017. All Rights Reserved. %% %% Licensed under the Apache License, Version 2.0 (the "License"); %% you may not use this file except in compliance with the License. @@ -923,7 +923,7 @@ xa([D|_] = Ds, [[Qual, D, {_, Line, AvpName}] | Avps], Dict, Key, Name) -> store_new({Key, {Name, AvpName}}, [Line, Qual, D], Dict, - [Name, Line], + [AvpName, Line], avp_already_referenced), Key, Name); -- cgit v1.2.3 From a85d5ae40463ac5157ce4c386c37d30505488466 Mon Sep 17 00:00:00 2001 From: Anders Svensson Date: Sat, 2 Sep 2017 16:17:38 +0200 Subject: Fix decode undef Function avp/5 isn't exported from dictionary modules. Not necessarily intentional, but don't just export it since that requires recompilation of all dictionary modules, since the function is in diameter_gen.hrl. Not having to recompile was the main motivation for moving most of the included code to module diameter_gen in commit 205521d3. This reveals a weakness in the decode of answers setting the E-bit: any AVP that isn't defined by the common application won't be decoded; the diameter_avp records that these are packed into (in the 'AVP' field of a message record, or equivalent) will have value = undefined. This is nothing new (same in OTP 19), but the values should be decoded. Fix it (and the lack of test coverage) in a subsequent commit that will add avp_dictionaries config. --- lib/diameter/src/base/diameter_gen.erl | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/diameter/src/base/diameter_gen.erl b/lib/diameter/src/base/diameter_gen.erl index 0aea982a54..307c3b4254 100644 --- a/lib/diameter/src/base/diameter_gen.erl +++ b/lib/diameter/src/base/diameter_gen.erl @@ -572,7 +572,7 @@ avp_decode(Data, AvpName, Opts, Mod, Mod) -> Mod:avp(decode, Data, AvpName, Opts); avp_decode(Data, AvpName, Opts, Mod, _) -> - Mod:avp(decode, Data, AvpName, Opts, Mod). + Mod:avp(decode, Data, AvpName, Opts#{module := Mod}). %% set_strict/3 %% -- cgit v1.2.3 From 22ce93c35f3bdc490cedc7d63529ed3e2fb20556 Mon Sep 17 00:00:00 2001 From: Anders Svensson Date: Wed, 30 Aug 2017 11:05:50 +0200 Subject: Add RFC 7683 Diameter Overload Indicator Conveyance text and dictionary Which motivates the avp_dictionaries config that will be added in a subsequent commit. --- lib/diameter/doc/standard/rfc7683.txt | 2355 +++++++++++++++++++++++++++++ lib/diameter/src/Makefile | 6 +- lib/diameter/src/dict/doic_rfc7683.dia | 50 + lib/diameter/src/modules.mk | 1 + lib/diameter/test/diameter_codec_test.erl | 3 +- 5 files changed, 2410 insertions(+), 5 deletions(-) create mode 100644 lib/diameter/doc/standard/rfc7683.txt create mode 100644 lib/diameter/src/dict/doic_rfc7683.dia diff --git a/lib/diameter/doc/standard/rfc7683.txt b/lib/diameter/doc/standard/rfc7683.txt new file mode 100644 index 0000000000..ab2392c6c0 --- /dev/null +++ b/lib/diameter/doc/standard/rfc7683.txt @@ -0,0 +1,2355 @@ + + + + + + +Internet Engineering Task Force (IETF) J. Korhonen, Ed. +Request for Comments: 7683 Broadcom Corporation +Category: Standards Track S. Donovan, Ed. +ISSN: 2070-1721 B. Campbell + Oracle + L. Morand + Orange Labs + October 2015 + + + Diameter Overload Indication Conveyance + +Abstract + + This specification defines a base solution for Diameter overload + control, referred to as Diameter Overload Indication Conveyance + (DOIC). + +Status of This Memo + + This is an Internet Standards Track document. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Further information on + Internet Standards is available in Section 2 of RFC 5741. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + http://www.rfc-editor.org/info/rfc7683. + +Copyright Notice + + Copyright (c) 2015 IETF Trust and the persons identified as the + document authors. All rights reserved. + + This document is subject to BCP 78 and the IETF Trust's Legal + Provisions Relating to IETF Documents + (http://trustee.ietf.org/license-info) in effect on the date of + publication of this document. Please review these documents + carefully, as they describe your rights and restrictions with respect + to this document. Code Components extracted from this document must + include Simplified BSD License text as described in Section 4.e of + the Trust Legal Provisions and are provided without warranty as + described in the Simplified BSD License. + + + + + +Korhonen, et al. Standards Track [Page 1] + +RFC 7683 DOIC October 2015 + + +Table of Contents + + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 + 2. Terminology and Abbreviations . . . . . . . . . . . . . . . . 3 + 3. Conventions Used in This Document . . . . . . . . . . . . . . 5 + 4. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 5 + 4.1. Piggybacking . . . . . . . . . . . . . . . . . . . . . . 6 + 4.2. DOIC Capability Announcement . . . . . . . . . . . . . . 7 + 4.3. DOIC Overload Condition Reporting . . . . . . . . . . . . 9 + 4.4. DOIC Extensibility . . . . . . . . . . . . . . . . . . . 11 + 4.5. Simplified Example Architecture . . . . . . . . . . . . . 12 + 5. Solution Procedures . . . . . . . . . . . . . . . . . . . . . 12 + 5.1. Capability Announcement . . . . . . . . . . . . . . . . . 12 + 5.1.1. Reacting Node Behavior . . . . . . . . . . . . . . . 13 + 5.1.2. Reporting Node Behavior . . . . . . . . . . . . . . . 13 + 5.1.3. Agent Behavior . . . . . . . . . . . . . . . . . . . 14 + 5.2. Overload Report Processing . . . . . . . . . . . . . . . 15 + 5.2.1. Overload Control State . . . . . . . . . . . . . . . 15 + 5.2.2. Reacting Node Behavior . . . . . . . . . . . . . . . 19 + 5.2.3. Reporting Node Behavior . . . . . . . . . . . . . . . 20 + 5.3. Protocol Extensibility . . . . . . . . . . . . . . . . . 22 + 6. Loss Algorithm . . . . . . . . . . . . . . . . . . . . . . . 23 + 6.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 23 + 6.2. Reporting Node Behavior . . . . . . . . . . . . . . . . . 24 + 6.3. Reacting Node Behavior . . . . . . . . . . . . . . . . . 24 + 7. Attribute Value Pairs . . . . . . . . . . . . . . . . . . . . 25 + 7.1. OC-Supported-Features AVP . . . . . . . . . . . . . . . . 25 + 7.2. OC-Feature-Vector AVP . . . . . . . . . . . . . . . . . . 25 + 7.3. OC-OLR AVP . . . . . . . . . . . . . . . . . . . . . . . 26 + 7.4. OC-Sequence-Number AVP . . . . . . . . . . . . . . . . . 26 + 7.5. OC-Validity-Duration AVP . . . . . . . . . . . . . . . . 26 + 7.6. OC-Report-Type AVP . . . . . . . . . . . . . . . . . . . 27 + 7.7. OC-Reduction-Percentage AVP . . . . . . . . . . . . . . . 27 + 7.8. AVP Flag Rules . . . . . . . . . . . . . . . . . . . . . 28 + 8. Error Response Codes . . . . . . . . . . . . . . . . . . . . 28 + 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 + 9.1. AVP Codes . . . . . . . . . . . . . . . . . . . . . . . . 29 + 9.2. New Registries . . . . . . . . . . . . . . . . . . . . . 29 + 10. Security Considerations . . . . . . . . . . . . . . . . . . . 30 + 10.1. Potential Threat Modes . . . . . . . . . . . . . . . . . 30 + 10.2. Denial-of-Service Attacks . . . . . . . . . . . . . . . 31 + 10.3. Noncompliant Nodes . . . . . . . . . . . . . . . . . . . 32 + 10.4. End-to-End Security Issues . . . . . . . . . . . . . . . 32 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 34 + 11.1. Normative References . . . . . . . . . . . . . . . . . . 34 + 11.2. Informative References . . . . . . . . . . . . . . . . . 34 + + + + + +Korhonen, et al. Standards Track [Page 2] + +RFC 7683 DOIC October 2015 + + + Appendix A. Issues Left for Future Specifications . . . . . . . 35 + A.1. Additional Traffic Abatement Algorithms . . . . . . . . . 35 + A.2. Agent Overload . . . . . . . . . . . . . . . . . . . . . 35 + A.3. New Error Diagnostic AVP . . . . . . . . . . . . . . . . 35 + Appendix B. Deployment Considerations . . . . . . . . . . . . . 35 + Appendix C. Considerations for Applications Integrating the DOIC + Solution . . . . . . . . . . . . . . . . . . . . . . 36 + C.1. Application Classification . . . . . . . . . . . . . . . 36 + C.2. Implications of Application Type Overload . . . . . . . . 37 + C.3. Request Transaction Classification . . . . . . . . . . . 38 + C.4. Request Type Overload Implications . . . . . . . . . . . 39 + Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 41 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42 + +1. Introduction + + This specification defines a base solution for Diameter overload + control, referred to as Diameter Overload Indication Conveyance + (DOIC), based on the requirements identified in [RFC7068]. + + This specification addresses Diameter overload control between + Diameter nodes that support the DOIC solution. The solution, which + is designed to apply to existing and future Diameter applications, + requires no changes to the Diameter base protocol [RFC6733] and is + deployable in environments where some Diameter nodes do not implement + the Diameter overload control solution defined in this specification. + + A new application specification can incorporate the overload control + mechanism specified in this document by making it mandatory to + implement for the application and referencing this specification + normatively. It is the responsibility of the Diameter application + designers to define how overload control mechanisms work on that + application. + + Note that the overload control solution defined in this specification + does not address all the requirements listed in [RFC7068]. A number + of features related to overload control are left for future + specifications. See Appendix A for a list of extensions that are + currently being considered. + +2. Terminology and Abbreviations + + Abatement + + Reaction to receipt of an overload report resulting in a reduction + in traffic sent to the reporting node. Abatement actions include + diversion and throttling. + + + + +Korhonen, et al. Standards Track [Page 3] + +RFC 7683 DOIC October 2015 + + + Abatement Algorithm + + An extensible method requested by reporting nodes and used by + reacting nodes to reduce the amount of traffic sent during an + occurrence of overload control. + + Diversion + + An overload abatement treatment where the reacting node selects + alternate destinations or paths for requests. + + Host-Routed Requests + + Requests that a reacting node knows will be served by a particular + host, either due to the presence of a Destination-Host Attribute + Value Pair (AVP) or by some other local knowledge on the part of + the reacting node. + + Overload Control State (OCS) + + Internal state maintained by a reporting or reacting node + describing occurrences of overload control. + + Overload Report (OLR) + + Overload control information for a particular overload occurrence + sent by a reporting node. + + Reacting Node + + A Diameter node that acts upon an overload report. + + Realm-Routed Requests + + Requests sent by a reacting node where the reacting node does not + know to which host the request will be routed. + + Reporting Node + + A Diameter node that generates an overload report. (This may or + may not be the overloaded node.) + + + + + + + + + + +Korhonen, et al. Standards Track [Page 4] + +RFC 7683 DOIC October 2015 + + + Throttling + + An abatement treatment that limits the number of requests sent by + the reacting node. Throttling can include a Diameter Client + choosing to not send requests, or a Diameter Agent or Server + rejecting requests with appropriate error responses. In both + cases, the result of the throttling is a permanent rejection of + the transaction. + +3. Conventions Used in This Document + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this + document are to be interpreted as described in RFC 2119 [RFC2119]. + + The interpretation from RFC 2119 [RFC2119] does not apply for the + above listed words when they are not used in all caps. + +4. Solution Overview + + The Diameter Overload Information Conveyance (DOIC) solution allows + Diameter nodes to request that other Diameter nodes perform overload + abatement actions, that is, actions to reduce the load offered to the + overloaded node or realm. + + A Diameter node that supports DOIC is known as a "DOIC node". Any + Diameter node can act as a DOIC node, including Diameter Clients, + Diameter Servers, and Diameter Agents. DOIC nodes are further + divided into "Reporting Nodes" and "Reacting Nodes." A reporting + node requests overload abatement by sending Overload Reports (OLRs). + + A reacting node acts upon OLRs and performs whatever actions are + needed to fulfill the abatement requests included in the OLRs. A + reporting node may report overload on its own behalf or on behalf of + other nodes. Likewise, a reacting node may perform overload + abatement on its own behalf or on behalf of other nodes. + + A Diameter node's role as a DOIC node is independent of its Diameter + role. For example, Diameter Agents may act as DOIC nodes, even + though they are not endpoints in the Diameter sense. Since Diameter + enables bidirectional applications, where Diameter Servers can send + requests towards Diameter Clients, a given Diameter node can + simultaneously act as both a reporting node and a reacting node. + + Likewise, a Diameter Agent may act as a reacting node from the + perspective of upstream nodes, and a reporting node from the + perspective of downstream nodes. + + + + +Korhonen, et al. Standards Track [Page 5] + +RFC 7683 DOIC October 2015 + + + DOIC nodes do not generate new messages to carry DOIC-related + information. Rather, they "piggyback" DOIC information over existing + Diameter messages by inserting new AVPs into existing Diameter + requests and responses. Nodes indicate support for DOIC, and any + needed DOIC parameters, by inserting an OC-Supported-Features AVP + (Section 7.1) into existing requests and responses. Reporting nodes + send OLRs by inserting OC-OLR AVPs (Section 7.3). + + A given OLR applies to the Diameter realm and application of the + Diameter message that carries it. If a reporting node supports more + than one realm and/or application, it reports independently for each + combination of realm and application. Similarly, the OC-Supported- + Features AVP applies to the realm and application of the enclosing + message. This implies that a node may support DOIC for one + application and/or realm, but not another, and may indicate different + DOIC parameters for each application and realm for which it supports + DOIC. + + Reacting nodes perform overload abatement according to an agreed-upon + abatement algorithm. An abatement algorithm defines the meaning of + some of the parameters of an OLR and the procedures required for + overload abatement. An overload abatement algorithm separates + Diameter requests into two sets. The first set contains the requests + that are to undergo overload abatement treatment of either throttling + or diversion. The second set contains the requests that are to be + given normal routing treatment. This document specifies a single + "must-support" algorithm, namely, the "loss" algorithm (Section 6). + Future specifications may introduce new algorithms. + + Overload conditions may vary in scope. For example, a single + Diameter node may be overloaded, in which case, reacting nodes may + attempt to send requests to other destinations. On the other hand, + an entire Diameter realm may be overloaded, in which case, such + attempts would do harm. DOIC OLRs have a concept of "report type" + (Section 7.6), where the type defines such behaviors. Report types + are extensible. This document defines report types for overload of a + specific host and for overload of an entire realm. + + DOIC works through non-supporting Diameter Agents that properly pass + unknown AVPs unchanged. + +4.1. Piggybacking + + There is no new Diameter application defined to carry overload- + related AVPs. The overload control AVPs defined in this + specification have been designed to be piggybacked on top of existing + + + + + +Korhonen, et al. Standards Track [Page 6] + +RFC 7683 DOIC October 2015 + + + application messages. This is made possible by adding the optional + overload control AVPs OC-OLR and OC-Supported-Features into existing + commands. + + Reacting nodes indicate support for DOIC by including the + OC-Supported-Features AVP in all request messages originated or + relayed by the reacting node. + + Reporting nodes indicate support for DOIC by including the + OC-Supported-Features AVP in all answer messages that are originated + or relayed by the reporting node and that are in response to a + request that contained the OC-Supported-Features AVP. Reporting + nodes may include overload reports using the OC-OLR AVP in answer + messages. + + Note that the overload control solution does not have fixed server + and client roles. The DOIC node role is determined based on the + message type: whether the message is a request (i.e., sent by a + "reacting node") or an answer (i.e., sent by a "reporting node"). + Therefore, in a typical client-server deployment, the Diameter Client + may report its overload condition to the Diameter Server for any + Diameter-Server-initiated message exchange. An example of such is + the Diameter Server requesting a re-authentication from a Diameter + Client. + +4.2. DOIC Capability Announcement + + The DOIC solution supports the ability for Diameter nodes to + determine if other nodes in the path of a request support the + solution. This capability is referred to as DOIC Capability + Announcement (DCA) and is separate from the Diameter Capability + Exchange. + + The DCA mechanism uses the OC-Supported-Features AVPs to indicate the + Diameter overload features supported. + + The first node in the path of a Diameter request that supports the + DOIC solution inserts the OC-Supported-Features AVP in the request + message. + + The individual features supported by the DOIC nodes are indicated in + the OC-Feature-Vector AVP. Any semantics associated with the + features will be defined in extension specifications that introduce + the features. + + Note: As discussed elsewhere in the document, agents in the path + of the request can modify the OC-Supported-Features AVP. + + + + +Korhonen, et al. Standards Track [Page 7] + +RFC 7683 DOIC October 2015 + + + Note: The DOIC solution must support deployments where Diameter + Clients and/or Diameter Servers do not support the DOIC solution. + In this scenario, Diameter Agents that support the DOIC solution + may handle overload abatement for the non-supporting Diameter + nodes. In this case, the DOIC agent will insert the OC-Supported- + Features AVP in requests that do not already contain one, telling + the reporting node that there is a DOIC node that will handle + overload abatement. For transactions where there was an + OC-Supporting-Features AVP in the request, the agent will insert + the OC-Supported-Features AVP in answers, telling the reacting + node that there is a reporting node. + + The OC-Feature-Vector AVP will always contain an indication of + support for the loss overload abatement algorithm defined in this + specification (see Section 6). This ensures that a reporting node + always supports at least one of the advertised abatement algorithms + received in a request messages. + + The reporting node inserts the OC-Supported-Features AVP in all + answer messages to requests that contained the OC-Supported-Features + AVP. The contents of the reporting node's OC-Supported-Features AVP + indicate the set of Diameter overload features supported by the + reporting node. This specification defines one exception -- the + reporting node only includes an indication of support for one + overload abatement algorithm, independent of the number of overload + abatement algorithms actually supported by the reacting node. The + overload abatement algorithm indicated is the algorithm that the + reporting node intends to use should it enter an overload condition. + Reacting nodes can use the indicated overload abatement algorithm to + prepare for possible overload reports and must use the indicated + overload abatement algorithm if traffic reduction is actually + requested. + + Note that the loss algorithm defined in this document is a + stateless abatement algorithm. As a result, it does not require + any actions by reacting nodes prior to the receipt of an overload + report. Stateful abatement algorithms that base the abatement + logic on a history of request messages sent might require reacting + nodes to maintain state in advance of receiving an overload report + to ensure that the overload reports can be properly handled. + + While it should only be done in exceptional circumstances and not + during an active occurrence of overload, a reacting node that wishes + to transition to a different abatement algorithm can stop advertising + support for the algorithm indicated by the reporting node, as long as + support for the loss algorithm is always advertised. + + + + + +Korhonen, et al. Standards Track [Page 8] + +RFC 7683 DOIC October 2015 + + + The DCA mechanism must also allow the scenario where the set of + features supported by the sender of a request and by agents in the + path of a request differ. In this case, the agent can update the + OC-Supported-Features AVP to reflect the mixture of the two sets of + supported features. + + Note: The logic to determine if the content of the OC-Supported- + Features AVP should be changed is out of scope for this document, + as is the logic to determine the content of a modified + OC-Supported-Features AVP. These are left to implementation + decisions. Care must be taken not to introduce interoperability + issues for downstream or upstream DOIC nodes. As such, the agent + must act as a fully compliant reporting node to the downstream + reacting node and as a fully compliant reacting node to the + upstream reporting node. + +4.3. DOIC Overload Condition Reporting + + As with DOIC capability announcement, overload condition reporting + uses new AVPs (Section 7.3) to indicate an overload condition. + + The OC-OLR AVP is referred to as an overload report. The OC-OLR AVP + includes the type of report, a sequence number, the length of time + that the report is valid, and AVPs specific to the abatement + algorithm. + + Two types of overload reports are defined in this document: host + reports and realm reports. + + A report of type "HOST_REPORT" is sent to indicate the overload of a + specific host, identified by the Origin-Host AVP of the message + containing the OLR, for the Application-ID indicated in the + transaction. When receiving an OLR of type "HOST_REPORT", a reacting + node applies overload abatement treatment to the host-routed requests + identified by the overload abatement algorithm (as defined in + Section 2) sent for this application to the overloaded host. + + A report of type "REALM_REPORT" is sent to indicate the overload of a + realm for the Application-ID indicated in the transaction. The + overloaded realm is identified by the Destination-Realm AVP of the + message containing the OLR. When receiving an OLR of type + "REALM_REPORT", a reacting node applies overload abatement treatment + to realm-routed requests identified by the overload abatement + algorithm (as defined in Section 2) sent for this application to the + overloaded realm. + + + + + + +Korhonen, et al. Standards Track [Page 9] + +RFC 7683 DOIC October 2015 + + + This document assumes that there is a single source for realm reports + for a given realm, or that if multiple nodes can send realm reports, + that each such node has full knowledge of the overload state of the + entire realm. A reacting node cannot distinguish between receiving + realm reports from a single node or from multiple nodes. + + Note: Known issues exist if there are multiple sources for + overload reports that apply to the same Diameter entity. Reacting + nodes have no way of determining the source and, as such, will + treat them as coming from a single source. Variance in sequence + numbers between the two sources can then cause incorrect overload + abatement treatment to be applied for indeterminate periods of + time. + + Reporting nodes are responsible for determining the need for a + reduction of traffic. The method for making this determination is + implementation specific and depends on the type of overload report + being generated. A host report might be generated by tracking use of + resources required by the host to handle transactions for the + Diameter application. A realm report generally impacts the traffic + sent to multiple hosts and, as such, requires tracking the capacity + of all servers able to handle realm-routed requests for the + application and realm. + + Once a reporting node determines the need for a reduction in traffic, + it uses the DOIC-defined AVPs to report on the condition. These AVPs + are included in answer messages sent or relayed by the reporting + node. The reporting node indicates the overload abatement algorithm + that is to be used to handle the traffic reduction in the + OC-Supported-Features AVP. The OC-OLR AVP is used to communicate + information about the requested reduction. + + Reacting nodes, upon receipt of an overload report, apply the + overload abatement algorithm to traffic impacted by the overload + report. The method used to determine the requests that are to + receive overload abatement treatment is dependent on the abatement + algorithm. The loss abatement algorithm is defined in this document + (Section 6). Other abatement algorithms can be defined in extensions + to the DOIC solution. + + Two types of overload abatement treatment are defined, diversion and + throttling. Reacting nodes are responsible for determining which + treatment is appropriate for individual requests. + + As the conditions that lead to the generation of the overload report + change, the reporting node can send new overload reports requesting + greater reduction if the condition gets worse or less reduction if + the condition improves. The reporting node sends an overload report + + + +Korhonen, et al. Standards Track [Page 10] + +RFC 7683 DOIC October 2015 + + + with a duration of zero to indicate that the overload condition has + ended and abatement is no longer needed. + + The reacting node also determines when the overload report expires + based on the OC-Validity-Duration AVP in the overload report and + stops applying the abatement algorithm when the report expires. + + Note that erroneous overload reports can be used for DoS attacks. + This includes the ability to indicate that a significant reduction in + traffic, up to and including a request for no traffic, should be sent + to a reporting node. As such, care should be taken to verify the + sender of overload reports. + +4.4. DOIC Extensibility + + The DOIC solution is designed to be extensible. This extensibility + is based on existing Diameter-based extensibility mechanisms, along + with the DOIC capability announcement mechanism. + + There are multiple categories of extensions that are expected. This + includes the definition of new overload abatement algorithms, the + definition of new report types, and the definition of new scopes of + messages impacted by an overload report. + + A DOIC node communicates supported features by including them in the + OC-Feature-Vector AVP, as a sub-AVP of OC-Supported-Features. Any + non-backwards-compatible DOIC extensions define new values for the + OC-Feature-Vector AVP. DOIC extensions also have the ability to add + new AVPs to the OC-Supported-Features AVP, if additional information + about the new feature is required. + + Overload reports can also be extended by adding new sub-AVPs to the + OC-OLR AVP, allowing reporting nodes to communicate additional + information about handling an overload condition. + + If necessary, new extensions can also define new AVPs that are not + part of the OC-Supported-Features and OC-OLR group AVPs. It is, + however, recommended that DOIC extensions use the OC-Supported- + Features AVP and OC-OLR AVP to carry all DOIC-related AVPs. + + + + + + + + + + + + +Korhonen, et al. Standards Track [Page 11] + +RFC 7683 DOIC October 2015 + + +4.5. Simplified Example Architecture + + Figure 1 illustrates the simplified architecture for Diameter + overload information conveyance. + + Realm X Same or other Realms + <--------------------------------------> <----------------------> + + + +--------+ : (optional) : + |Diameter| : : + |Server A|--+ .--. : +--------+ : .--. + +--------+ | _( `. : |Diameter| : _( `. +--------+ + +--( )--:-| Agent |-:--( )--|Diameter| + +--------+ | ( ` . ) ) : +--------+ : ( ` . ) ) | Client | + |Diameter|--+ `--(___.-' : : `--(___.-' +--------+ + |Server B| : : + +--------+ : : + + End-to-end Overload Indication + 1) <-----------------------------------------------> + Diameter Application Y + + Overload Indication A Overload Indication A' + 2) <----------------------> <----------------------> + Diameter Application Y Diameter Application Y + + Figure 1: Simplified Architecture Choices for Overload Indication + Delivery + + In Figure 1, the Diameter overload indication can be conveyed (1) + end-to-end between servers and clients or (2) between servers and the + Diameter Agent inside the realm and then between the Diameter Agent + and the clients. + +5. Solution Procedures + + This section outlines the normative behavior for the DOIC solution. + +5.1. Capability Announcement + + This section defines DOIC Capability Announcement (DCA) behavior. + + Note: This specification assumes that changes in DOIC node + capabilities are relatively rare events that occur as a result of + administrative action. Reacting nodes ought to minimize changes + that force the reporting node to change the features being used, + especially during active overload conditions. But even if + + + +Korhonen, et al. Standards Track [Page 12] + +RFC 7683 DOIC October 2015 + + + reacting nodes avoid such changes, reporting nodes still have to + be prepared for them to occur. For example, differing + capabilities between multiple reacting nodes may still force a + reporting node to select different features on a per-transaction + basis. + +5.1.1. Reacting Node Behavior + + A reacting node MUST include the OC-Supported-Features AVP in all + requests. It MAY include the OC-Feature-Vector AVP, as a sub-AVP of + OC-Supported-Features. If it does so, it MUST indicate support for + the "loss" algorithm. If the reacting node is configured to support + features (including other algorithms) in addition to the loss + algorithm, it MUST indicate such support in an OC-Feature-Vector AVP. + + An OC-Supported-Features AVP in answer messages indicates there is a + reporting node for the transaction. The reacting node MAY take + action, for example, creating state for some stateful abatement + algorithm, based on the features indicated in the OC-Feature-Vector + AVP. + + Note: The loss abatement algorithm does not require stateful + behavior when there is no active overload report. + + Reacting nodes need to be prepared for the reporting node to change + selected algorithms. This can happen at any time, including when the + reporting node has sent an active overload report. The reacting node + can minimize the potential for changes by modifying the advertised + abatement algorithms sent to an overloaded reporting node to the + currently selected algorithm and loss (or just loss if it is the + currently selected algorithm). This has the effect of limiting the + potential change in abatement algorithm from the currently selected + algorithm to loss, avoiding changes to more complex abatement + algorithms that require state to operate properly. + +5.1.2. Reporting Node Behavior + + Upon receipt of a request message, a reporting node determines if + there is a reacting node for the transaction based on the presence of + the OC-Supported-Features AVP in the request message. + + If the request message contains an OC-Supported-Features AVP, then a + reporting node MUST include the OC-Supported-Features AVP in the + answer message for that transaction. + + Note: Capability announcement is done on a per-transaction basis. + The reporting node cannot assume that the capabilities announced + by a reacting node will be the same between transactions. + + + +Korhonen, et al. Standards Track [Page 13] + +RFC 7683 DOIC October 2015 + + + A reporting node MUST NOT include the OC-Supported-Features AVP, + OC-OLR AVP, or any other overload control AVPs defined in extension + documents in response messages for transactions where the request + message does not include the OC-Supported-Features AVP. Lack of the + OC-Supported-Features AVP in the request message indicates that there + is no reacting node for the transaction. + + A reporting node knows what overload control functionality is + supported by the reacting node based on the content or absence of the + OC-Feature-Vector AVP within the OC-Supported-Features AVP in the + request message. + + A reporting node MUST select a single abatement algorithm in the + OC-Feature-Vector AVP. The abatement algorithm selected MUST + indicate the abatement algorithm the reporting node wants the + reacting node to use when the reporting node enters an overload + condition. + + The abatement algorithm selected MUST be from the set of abatement + algorithms contained in the request message's OC-Feature-Vector AVP. + + A reporting node that selects the loss algorithm may do so by + including the OC-Feature-Vector AVP with an explicit indication of + the loss algorithm, or it MAY omit the OC-Feature-Vector AVP. If it + selects a different algorithm, it MUST include the OC-Feature-Vector + AVP with an explicit indication of the selected algorithm. + + The reporting node SHOULD indicate support for other DOIC features + defined in extension documents that it supports and that apply to the + transaction. It does so using the OC-Feature-Vector AVP. + + Note: Not all DOIC features will apply to all Diameter + applications or deployment scenarios. The features included in + the OC-Feature-Vector AVP are based on local policy of the + reporting node. + +5.1.3. Agent Behavior + + Diameter Agents that support DOIC can ensure that all messages + relayed by the agent contain the OC-Supported-Features AVP. + + A Diameter Agent MAY take on reacting node behavior for Diameter + endpoints that do not support the DOIC solution. A Diameter Agent + detects that a Diameter endpoint does not support DOIC reacting node + behavior when there is no OC-Supported-Features AVP in a request + message. + + + + + +Korhonen, et al. Standards Track [Page 14] + +RFC 7683 DOIC October 2015 + + + For a Diameter Agent to be a reacting node for a non-supporting + Diameter endpoint, the Diameter Agent MUST include the OC-Supported- + Features AVP in request messages it relays that do not contain the + OC-Supported-Features AVP. + + A Diameter Agent MAY take on reporting node behavior for Diameter + endpoints that do not support the DOIC solution. The Diameter Agent + MUST have visibility to all traffic destined for the non-supporting + host in order to become the reporting node for the Diameter endpoint. + A Diameter Agent detects that a Diameter endpoint does not support + DOIC reporting node behavior when there is no OC-Supported-Features + AVP in an answer message for a transaction that contained the + OC-Supported-Features AVP in the request message. + + If a request already has the OC-Supported-Features AVP, a Diameter + Agent MAY modify it to reflect the features appropriate for the + transaction. Otherwise, the agent relays the OC-Supported-Features + AVP without change. + + Example: If the agent supports a superset of the features reported + by the reacting node, then the agent might choose, based on local + policy, to advertise that superset of features to the reporting + node. + + If the Diameter Agent changes the OC-Supported-Features AVP in a + request message, then it is likely it will also need to modify the + OC-Supported-Features AVP in the answer message for the transaction. + A Diameter Agent MAY modify the OC-Supported-Features AVP carried in + answer messages. + + When making changes to the OC-Supported-Features or OC-OLR AVPs, the + Diameter Agent needs to ensure consistency in its behavior with both + upstream and downstream DOIC nodes. + +5.2. Overload Report Processing + +5.2.1. Overload Control State + + Both reacting and reporting nodes maintain Overload Control State + (OCS) for active overload conditions. The following sections define + behavior associated with that OCS. + + The contents of the OCS in the reporting node and in the reacting + node represent logical constructs. The actual internal physical + structure of the state included in the OCS is an implementation + decision. + + + + + +Korhonen, et al. Standards Track [Page 15] + +RFC 7683 DOIC October 2015 + + +5.2.1.1. Overload Control State for Reacting Nodes + + A reacting node maintains the following OCS per supported Diameter + application: + + o a host-type OCS entry for each Destination-Host to which it sends + host-type requests and + + o a realm-type OCS entry for each Destination-Realm to which it + sends realm-type requests. + + A host-type OCS entry is identified by the pair of Application-ID and + the node's DiameterIdentity. + + A realm-type OCS entry is identified by the pair of Application-ID + and realm. + + The host-type and realm-type OCS entries include the following + information (the actual information stored is an implementation + decision): + + o Sequence number (as received in OC-OLR; see Section 7.3) + + o Time of expiry (derived from OC-Validity-Duration AVP received in + the OC-OLR AVP and time of reception of the message carrying + OC-OLR AVP) + + o Selected abatement algorithm (as received in the OC-Supported- + Features AVP) + + o Input data that is abatement algorithm specific (as received in + the OC-OLR AVP -- for example, OC-Reduction-Percentage for the + loss abatement algorithm) + +5.2.1.2. Overload Control State for Reporting Nodes + + A reporting node maintains OCS entries per supported Diameter + application, per supported (and eventually selected) abatement + algorithm, and per report type. + + An OCS entry is identified by the tuple of Application-ID, report + type, and abatement algorithm, and it includes the following + information (the actual information stored is an implementation + decision): + + o Sequence number + + o Validity duration + + + +Korhonen, et al. Standards Track [Page 16] + +RFC 7683 DOIC October 2015 + + + o Expiration time + + o Input data that is algorithm specific (for example, the reduction + percentage for the loss abatement algorithm) + +5.2.1.3. Reacting Node's Maintenance of Overload Control State + + When a reacting node receives an OC-OLR AVP, it MUST determine if it + is for an existing or new overload condition. + + Note: For the remainder of this section, the term "OLR" refers to + the combination of the contents of the received OC-OLR AVP and the + abatement algorithm indicated in the received OC-Supported- + Features AVP. + + When receiving an answer message with multiple OLRs of different + supported report types, a reacting node MUST process each received + OLR. + + The OLR is for an existing overload condition if a reacting node has + an OCS that matches the received OLR. + + For a host report, this means it matches the Application-ID and the + host's DiameterIdentity in an existing host OCS entry. + + For a realm report, this means it matches the Application-ID and the + realm in an existing realm OCS entry. + + If the OLR is for an existing overload condition, then a reacting + node MUST determine if the OLR is a retransmission or an update to + the existing OLR. + + If the sequence number for the received OLR is greater than the + sequence number stored in the matching OCS entry, then a reacting + node MUST update the matching OCS entry. + + If the sequence number for the received OLR is less than or equal to + the sequence number in the matching OCS entry, then a reacting node + MUST silently ignore the received OLR. The matching OCS MUST NOT be + updated in this case. + + If the reacting node determines that the sequence number has rolled + over, then the reacting node MUST update the matching OCS entry. + This can be determined by recognizing that the number has changed + from a value within 1% of the maximum value in the OC-Sequence-Number + AVP to a value within 1% of the minimum value in the OC-Sequence- + Number AVP. + + + + +Korhonen, et al. Standards Track [Page 17] + +RFC 7683 DOIC October 2015 + + + If the received OLR is for a new overload condition, then a reacting + node MUST generate a new OCS entry for the overload condition. + + For a host report, this means a reacting node creates an OCS entry + with the Application-ID in the received message and DiameterIdentity + of the Origin-Host in the received message. + + Note: This solution assumes that the Origin-Host AVP in the answer + message included by the reporting node is not changed along the + path to the reacting node. + + For a realm report, this means a reacting node creates an OCS entry + with the Application-ID in the received message and realm of the + Origin-Realm in the received message. + + If the received OLR contains a validity duration of zero ("0"), then + a reacting node MUST update the OCS entry as being expired. + + Note: It is not necessarily appropriate to delete the OCS entry, + as the recommended behavior is that the reacting node slowly + returns to full traffic when ending an overload abatement period. + + The reacting node does not delete an OCS when receiving an answer + message that does not contain an OC-OLR AVP (i.e., absence of OLR + means "no change"). + +5.2.1.4. Reporting Node's Maintenance of Overload Control State + + A reporting node SHOULD create a new OCS entry when entering an + overload condition. + + Note: If a reporting node knows through absence of the + OC-Supported-Features AVP in received messages that there are no + reacting nodes supporting DOIC, then the reporting node can choose + to not create OCS entries. + + When generating a new OCS entry, the sequence number SHOULD be set to + zero ("0"). + + When generating sequence numbers for new overload conditions, the new + sequence number MUST be greater than any sequence number in an active + (unexpired) overload report for the same application and report type + previously sent by the reporting node. This property MUST hold over + a reboot of the reporting node. + + + + + + + +Korhonen, et al. Standards Track [Page 18] + +RFC 7683 DOIC October 2015 + + + Note: One way of addressing this over a reboot of a reporting node + is to use a timestamp for the first overload condition that occurs + after the report and to start using sequences beginning with zero + for subsequent overload conditions. + + A reporting node MUST update an OCS entry when it needs to adjust the + validity duration of the overload condition at reacting nodes. + + Example: If a reporting node wishes to instruct reacting nodes to + continue overload abatement for a longer period of time than + originally communicated. This also applies if the reporting node + wishes to shorten the period of time that overload abatement is to + continue. + + A reporting node MUST update an OCS entry when it wishes to adjust + any parameters specific to the abatement algorithm, including, for + example, the reduction percentage used for the loss abatement + algorithm. + + Example: If a reporting node wishes to change the reduction + percentage either higher (if the overload condition has worsened) + or lower (if the overload condition has improved), then the + reporting node would update the appropriate OCS entry. + + A reporting node MUST increment the sequence number associated with + the OCS entry anytime the contents of the OCS entry are changed. + This will result in a new sequence number being sent to reacting + nodes, instructing them to process the OC-OLR AVP. + + A reporting node SHOULD update an OCS entry with a validity duration + of zero ("0") when the overload condition ends. + + Note: If a reporting node knows that the OCS entries in the + reacting nodes are near expiration, then the reporting node might + decide not to send an OLR with a validity duration of zero. + + A reporting node MUST keep an OCS entry with a validity duration of + zero ("0") for a period of time long enough to ensure that any + unexpired reacting node's OCS entry created as a result of the + overload condition in the reporting node is deleted. + +5.2.2. Reacting Node Behavior + + When a reacting node sends a request, it MUST determine if that + request matches an active OCS. + + + + + + +Korhonen, et al. Standards Track [Page 19] + +RFC 7683 DOIC October 2015 + + + If the request matches an active OCS, then the reacting node MUST use + the overload abatement algorithm indicated in the OCS to determine if + the request is to receive overload abatement treatment. + + For the loss abatement algorithm defined in this specification, see + Section 6 for the overload abatement algorithm logic applied. + + If the overload abatement algorithm selects the request for overload + abatement treatment, then the reacting node MUST apply overload + abatement treatment on the request. The abatement treatment applied + depends on the context of the request. + + If diversion abatement treatment is possible (i.e., a different path + for the request can be selected where the overloaded node is not part + of the different path), then the reacting node SHOULD apply diversion + abatement treatment to the request. The reacting node MUST apply + throttling abatement treatment to requests identified for abatement + treatment when diversion treatment is not possible or was not + applied. + + Note: This only addresses the case where there are two defined + abatement treatments, diversion and throttling. Any extension + that defines a new abatement treatment must also define its + interaction with existing treatments. + + If the overload abatement treatment results in throttling of the + request and if the reacting node is an agent, then the agent MUST + send an appropriate error as defined in Section 8. + + Diameter endpoints that throttle requests need to do so according to + the rules of the client application. Those rules will vary by + application and are beyond the scope of this document. + + In the case that the OCS entry indicated no traffic was to be sent to + the overloaded entity and the validity duration expires, then + overload abatement associated with the overload report MUST be ended + in a controlled fashion. + +5.2.3. Reporting Node Behavior + + If there is an active OCS entry, then a reporting node SHOULD include + the OC-OLR AVP in all answers to requests that contain the + OC-Supported-Features AVP and that match the active OCS entry. + + Note: A request matches 1) if the Application-ID in the request + matches the Application-ID in any active OCS entry and 2) if the + report type in the OCS entry matches a report type supported by + the reporting node as indicated in the OC-Supported-Features AVP. + + + +Korhonen, et al. Standards Track [Page 20] + +RFC 7683 DOIC October 2015 + + + The contents of the OC-OLR AVP depend on the selected algorithm. + + A reporting node MAY choose to not resend an overload report to a + reacting node if it can guarantee that this overload report is + already active in the reacting node. + + Note: In some cases (e.g., when there are one or more agents in + the path between reporting and reacting nodes, or when overload + reports are discarded by reacting nodes), a reporting node may not + be able to guarantee that the reacting node has received the + report. + + A reporting node MUST NOT send overload reports of a type that has + not been advertised as supported by the reacting node. + + Note: A reacting node implicitly advertises support for the host + and realm report types by including the OC-Supported-Features AVP + in the request. Support for other report types will be explicitly + indicated by new feature bits in the OC-Feature-Vector AVP. + + A reporting node SHOULD explicitly indicate the end of an overload + occurrence by sending a new OLR with OC-Validity-Duration set to a + value of zero ("0"). The reporting node SHOULD ensure that all + reacting nodes receive the updated overload report. + + A reporting node MAY rely on the OC-Validity-Duration AVP values for + the implicit cleanup of overload control state on the reacting node. + + Note: All OLRs sent have an expiration time calculated by adding + the validity duration contained in the OLR to the time the message + was sent. Transit time for the OLR can be safely ignored. The + reporting node can ensure that all reacting nodes have received + the OLR by continuing to send it in answer messages until the + expiration time for all OLRs sent for that overload condition have + expired. + + When a reporting node sends an OLR, it effectively delegates any + necessary throttling to downstream nodes. If the reporting node also + locally throttles the same set of messages, the overall number of + throttled requests may be higher than intended. Therefore, before + applying local message throttling, a reporting node needs to check if + these messages match existing OCS entries, indicating that these + messages have survived throttling applied by downstream nodes that + have received the related OLR. + + However, even if the set of messages match existing OCS entries, the + reporting node can still apply other abatement methods such as + diversion. The reporting node might also need to throttle requests + + + +Korhonen, et al. Standards Track [Page 21] + +RFC 7683 DOIC October 2015 + + + for reasons other than overload. For example, an agent or server + might have a configured rate limit for each client and might throttle + requests that exceed that limit, even if such requests had already + been candidates for throttling by downstream nodes. The reporting + node also has the option to send new OLRs requesting greater + reductions in traffic, reducing the need for local throttling. + + A reporting node SHOULD decrease requested overload abatement + treatment in a controlled fashion to avoid oscillations in traffic. + + Example: A reporting node might wait some period of time after + overload ends before terminating the OLR, or it might send a + series of OLRs indicating progressively less overload severity. + +5.3. Protocol Extensibility + + The DOIC solution can be extended. Types of potential extensions + include new traffic abatement algorithms, new report types, or other + new functionality. + + When defining a new extension that requires new normative behavior, + the specification must define a new feature for the OC-Feature-Vector + AVP. This feature bit is used to communicate support for the new + feature. + + The extension may define new AVPs for use in the DOIC Capability + Announcement and for use in DOIC overload reporting. These new AVPs + SHOULD be defined to be extensions to the OC-Supported-Features or + OC-OLR AVPs defined in this document. + + The Grouped AVP extension mechanisms defined in [RFC6733] apply. + This allows, for example, defining a new feature that is mandatory to + be understood even when piggybacked on an existing application. + + When defining new report type values, the corresponding specification + must define the semantics of the new report types and how they affect + the OC-OLR AVP handling. + + The OC-Supported-Feature and OC-OLR AVPs can be expanded with + optional sub-AVPs only if a legacy DOIC implementation can safely + ignore them without breaking backward compatibility for the given + OC-Report-Type AVP value. Any new sub-AVPs must not require that the + M-bit be set. + + Documents that introduce new report types must describe any + limitations on their use across non-supporting agents. + + + + + +Korhonen, et al. Standards Track [Page 22] + +RFC 7683 DOIC October 2015 + + + As with any Diameter specification, RFC 6733 requires all new AVPs to + be registered with IANA. See Section 9 for the required procedures. + New features (feature bits in the OC-Feature-Vector AVP) and report + types (in the OC-Report-Type AVP) MUST be registered with IANA. + +6. Loss Algorithm + + This section documents the Diameter overload loss abatement + algorithm. + +6.1. Overview + + The DOIC specification supports the ability for multiple overload + abatement algorithms to be specified. The abatement algorithm used + for any instance of overload is determined by the DOIC Capability + Announcement process documented in Section 5.1. + + The loss algorithm described in this section is the default algorithm + that must be supported by all Diameter nodes that support DOIC. + + The loss algorithm is designed to be a straightforward and stateless + overload abatement algorithm. It is used by reporting nodes to + request a percentage reduction in the amount of traffic sent. The + traffic impacted by the requested reduction depends on the type of + overload report. + + Reporting nodes request the stateless reduction of the number of + requests by an indicated percentage. This percentage reduction is in + comparison to the number of messages the node otherwise would send, + regardless of how many requests the node might have sent in the past. + + From a conceptual level, the logic at the reacting node could be + outlined as follows. + + 1. An overload report is received, and the associated OCS is either + saved or updated (if required) by the reacting node. + + 2. A new Diameter request is generated by the application running on + the reacting node. + + 3. The reacting node determines that an active overload report + applies to the request, as indicated by the corresponding OCS + entry. + + 4. The reacting node determines if overload abatement treatment + should be applied to the request. One approach that could be + taken for each request is to select a uniformly selected random + number between 1 and 100. If the random number is less than or + + + +Korhonen, et al. Standards Track [Page 23] + +RFC 7683 DOIC October 2015 + + + equal to the indicated reduction percentage, then the request is + given abatement treatment; otherwise, the request is given normal + routing treatment. + +6.2. Reporting Node Behavior + + The method a reporting node uses to determine the amount of traffic + reduction required to address an overload condition is an + implementation decision. + + When a reporting node that has selected the loss abatement algorithm + determines the need to request a reduction in traffic, it includes an + OC-OLR AVP in answer messages as described in Section 5.2.3. + + When sending the OC-OLR AVP, the reporting node MUST indicate a + percentage reduction in the OC-Reduction-Percentage AVP. + + The reporting node MAY change the reduction percentage in subsequent + overload reports. When doing so, the reporting node must conform to + overload report handling specified in Section 5.2.3. + +6.3. Reacting Node Behavior + + The method a reacting node uses to determine which request messages + are given abatement treatment is an implementation decision. + + When receiving an OC-OLR in an answer message where the algorithm + indicated in the OC-Supported-Features AVP is the loss algorithm, the + reacting node MUST apply abatement treatment to the requested + percentage of request messages sent. + + Note: The loss algorithm is a stateless algorithm. As a result, + the reacting node does not guarantee that there will be an + absolute reduction in traffic sent. Rather, it guarantees that + the requested percentage of new requests will be given abatement + treatment. + + If the reacting node comes out of the 100% traffic reduction + (meaning, it has received an OLR indicating that no traffic should be + sent, as a result of the overload report timing out), the reacting + node sending the traffic SHOULD be conservative and, for example, + first send "probe" messages to learn the overload condition of the + overloaded node before converging to any traffic amount/rate decided + by the sender. Similar concerns apply in all cases when the overload + report times out, unless the previous overload report stated 0% + reduction. + + + + + +Korhonen, et al. Standards Track [Page 24] + +RFC 7683 DOIC October 2015 + + + Note: The goal of this behavior is to reduce the probability of + overload condition thrashing where an immediate transition from + 100% reduction to 0% reduction results in the reporting node + moving quickly back into an overload condition. + +7. Attribute Value Pairs + + This section describes the encoding and semantics of the Diameter + Overload Indication Attribute Value Pairs (AVPs) defined in this + document. + + Refer to Section 4 of [RFC6733] for more information on AVPs and AVP + data types. + +7.1. OC-Supported-Features AVP + + The OC-Supported-Features AVP (AVP Code 621) is of type Grouped and + serves two purposes. First, it announces a node's support for the + DOIC solution in general. Second, it contains the description of the + supported DOIC features of the sending node. The OC-Supported- + Features AVP MUST be included in every Diameter request message a + DOIC supporting node sends. + + OC-Supported-Features ::= < AVP Header: 621 > + [ OC-Feature-Vector ] + * [ AVP ] + +7.2. OC-Feature-Vector AVP + + The OC-Feature-Vector AVP (AVP Code 622) is of type Unsigned64 and + contains a 64-bit flags field of announced capabilities of a DOIC + node. The value of zero (0) is reserved. + + The OC-Feature-Vector sub-AVP is used to announce the DOIC features + supported by the DOIC node, in the form of a flag-bits field in which + each bit announces one feature or capability supported by the node. + The absence of the OC-Feature-Vector AVP in request messages + indicates that only the default traffic abatement algorithm described + in this specification is supported. The absence of the OC-Feature- + Vector AVP in answer messages indicates that the default traffic + abatement algorithm described in this specification is selected + (while other traffic abatement algorithms may be supported), and no + features other than abatement algorithms are supported. + + + + + + + + +Korhonen, et al. Standards Track [Page 25] + +RFC 7683 DOIC October 2015 + + + The following capability is defined in this document: + + OLR_DEFAULT_ALGO (0x0000000000000001) + + When this flag is set by the a DOIC reacting node, it means that + the default traffic abatement (loss) algorithm is supported. When + this flag is set by a DOIC reporting node, it means that the loss + algorithm will be used for requested overload abatement. + +7.3. OC-OLR AVP + + The OC-OLR AVP (AVP Code 623) is of type Grouped and contains the + information necessary to convey an overload report on an overload + condition at the reporting node. The application the OC-OLR AVP + applies to is identified by the Application-ID found in the Diameter + message header. The host or realm the OC-OLR AVP concerns is + determined from the Origin-Host AVP and/or Origin-Realm AVP found in + the encapsulating Diameter command. The OC-OLR AVP is intended to be + sent only by a reporting node. + + OC-OLR ::= < AVP Header: 623 > + < OC-Sequence-Number > + < OC-Report-Type > + [ OC-Reduction-Percentage ] + [ OC-Validity-Duration ] + * [ AVP ] + +7.4. OC-Sequence-Number AVP + + The OC-Sequence-Number AVP (AVP Code 624) is of type Unsigned64. Its + usage in the context of overload control is described in Section 5.2. + + From the functionality point of view, the OC-Sequence-Number AVP is + used as a nonvolatile increasing counter for a sequence of overload + reports between two DOIC nodes for the same overload occurrence. + Sequence numbers are treated in a unidirectional manner, i.e., two + sequence numbers in each direction between two DOIC nodes are not + related or correlated. + +7.5. OC-Validity-Duration AVP + + The OC-Validity-Duration AVP (AVP Code 625) is of type Unsigned32 and + indicates in seconds the validity time of the overload report. The + number of seconds is measured after reception of the first OC-OLR AVP + with a given value of OC-Sequence-Number AVP. The default value for + the OC-Validity-Duration AVP is 30 seconds. When the OC-Validity- + Duration AVP is not present in the OC-OLR AVP, the default value + applies. The maximum value for the OC-Validity-Duration AVP is + + + +Korhonen, et al. Standards Track [Page 26] + +RFC 7683 DOIC October 2015 + + + 86,400 seconds (24 hours). If the value received in the OC-Validity- + Duration is greater than the maximum value, then the default value + applies. + +7.6. OC-Report-Type AVP + + The OC-Report-Type AVP (AVP Code 626) is of type Enumerated. The + value of the AVP describes what the overload report concerns. The + following values are initially defined: + + HOST_REPORT 0 + The overload report is for a host. Overload abatement treatment + applies to host-routed requests. + + REALM_REPORT 1 + The overload report is for a realm. Overload abatement treatment + applies to realm-routed requests. + + The values 2-4294967295 are unassigned. + +7.7. OC-Reduction-Percentage AVP + + The OC-Reduction-Percentage AVP (AVP Code 627) is of type Unsigned32 + and describes the percentage of the traffic that the sender is + requested to reduce, compared to what it otherwise would send. The + OC-Reduction-Percentage AVP applies to the default (loss) algorithm + specified in this specification. However, the AVP can be reused for + future abatement algorithms, if its semantics fit into the new + algorithm. + + The value of the Reduction-Percentage AVP is between zero (0) and one + hundred (100). Values greater than 100 are ignored. The value of + 100 means that all traffic is to be throttled, i.e., the reporting + node is under a severe load and ceases to process any new messages. + The value of 0 means that the reporting node is in a stable state and + has no need for the reacting node to apply any traffic abatement. + + + + + + + + + + + + + + + +Korhonen, et al. Standards Track [Page 27] + +RFC 7683 DOIC October 2015 + + +7.8. AVP Flag Rules + + +---------+ + |AVP flag | + |rules | + +----+----+ + AVP Section | |MUST| + Attribute Name Code Defined Value Type |MUST| NOT| + +--------------------------------------------------+----+----+ + |OC-Supported-Features 621 7.1 Grouped | | V | + +--------------------------------------------------+----+----+ + |OC-Feature-Vector 622 7.2 Unsigned64 | | V | + +--------------------------------------------------+----+----+ + |OC-OLR 623 7.3 Grouped | | V | + +--------------------------------------------------+----+----+ + |OC-Sequence-Number 624 7.4 Unsigned64 | | V | + +--------------------------------------------------+----+----+ + |OC-Validity-Duration 625 7.5 Unsigned32 | | V | + +--------------------------------------------------+----+----+ + |OC-Report-Type 626 7.6 Enumerated | | V | + +--------------------------------------------------+----+----+ + |OC-Reduction | | | + | -Percentage 627 7.7 Unsigned32 | | V | + +--------------------------------------------------+----+----+ + + As described in the Diameter base protocol [RFC6733], the M-bit usage + for a given AVP in a given command may be defined by the application. + +8. Error Response Codes + + When a DOIC node rejects a Diameter request due to overload, the DOIC + node MUST select an appropriate error response code. This + determination is made based on the probability of the request + succeeding if retried on a different path. + + Note: This only applies for DOIC nodes that are not the originator + of the request. + + A reporting node rejecting a Diameter request due to an overload + condition SHOULD send a DIAMETER_TOO_BUSY error response, if it can + assume that the same request may succeed on a different path. + + If a reporting node knows or assumes that the same request will not + succeed on a different path, the DIAMETER_UNABLE_TO_COMPLY error + response SHOULD be used. Retrying would consume valuable resources + during an occurrence of overload. + + + + + +Korhonen, et al. Standards Track [Page 28] + +RFC 7683 DOIC October 2015 + + + For instance, if the request arrived at the reporting node without + a Destination-Host AVP, then the reporting node might determine + that there is an alternative Diameter node that could successfully + process the request and that retrying the transaction would not + negatively impact the reporting node. DIAMETER_TOO_BUSY would be + sent in this case. + + If the request arrived at the reporting node with a Destination- + Host AVP populated with its own Diameter identity, then the + reporting node can assume that retrying the request would result + in it coming to the same reporting node. + DIAMETER_UNABLE_TO_COMPLY would be sent in this case. + + A second example is when an agent that supports the DOIC solution + is performing the role of a reacting node for a non-supporting + client. Requests that are rejected as a result of DOIC throttling + by the agent in this scenario would generally be rejected with a + DIAMETER_UNABLE_TO_COMPLY response code. + +9. IANA Considerations + +9.1. AVP Codes + + New AVPs defined by this specification are listed in Section 7. All + AVP codes are allocated from the "AVP Codes" sub-registry under the + "Authentication, Authorization, and Accounting (AAA) Parameters" + registry. + +9.2. New Registries + + Two new registries have been created in the "AVP Specific Values" + sub-registry under the "Authentication, Authorization, and Accounting + (AAA) Parameters" registry. + + A new "OC-Feature-Vector AVP Values (code 622)" registry has been + created. This registry contains the following: + + Feature Vector Value Name + + Feature Vector Value + + Specification defining the new value + + See Section 7.2 for the initial Feature Vector Value in the registry. + This specification defines the value. New values can be added to the + registry using the Specification Required policy [RFC5226]. + + + + + +Korhonen, et al. Standards Track [Page 29] + +RFC 7683 DOIC October 2015 + + + A new "OC-Report-Type AVP Values (code 626)" registry has been + created. This registry contains the following: + + Report Type Value Name + + Report Type Value + + Specification defining the new value + + See Section 7.6 for the initial assignment in the registry. New + types can be added using the Specification Required policy [RFC5226]. + +10. Security Considerations + + DOIC gives Diameter nodes the ability to request that downstream + nodes send fewer Diameter requests. Nodes do this by exchanging + overload reports that directly effect this reduction. This exchange + is potentially subject to multiple methods of attack and has the + potential to be used as a denial-of-service (DoS) attack vector. For + instance, a series of injected realm OLRs with a requested reduction + percentage of 100% could be used to completely eliminate any traffic + from being sent to that realm. + + Overload reports may contain information about the topology and + current status of a Diameter network. This information is + potentially sensitive. Network operators may wish to control + disclosure of overload reports to unauthorized parties to avoid their + use for competitive intelligence or to target attacks. + + Diameter does not include features to provide end-to-end + authentication, integrity protection, or confidentiality. This may + cause complications when sending overload reports between non- + adjacent nodes. + +10.1. Potential Threat Modes + + The Diameter protocol involves transactions in the form of requests + and answers exchanged between clients and servers. These clients and + servers may be peers, that is, they may share a direct transport + (e.g., TCP or SCTP) connection, or the messages may traverse one or + more intermediaries, known as Diameter Agents. Diameter nodes use + TLS, DTLS, or IPsec to authenticate peers and to provide + confidentiality and integrity protection of traffic between peers. + Nodes can make authorization decisions based on the peer identities + authenticated at the transport layer. + + + + + + +Korhonen, et al. Standards Track [Page 30] + +RFC 7683 DOIC October 2015 + + + When agents are involved, this presents an effectively transitive + trust model. That is, a Diameter client or server can authorize an + agent for certain actions, but it must trust that agent to make + appropriate authorization decisions about its peers, and so on. + Since confidentiality and integrity protection occur at the transport + layer, agents can read, and perhaps modify, any part of a Diameter + message, including an overload report. + + There are several ways an attacker might attempt to exploit the + overload control mechanism. An unauthorized third party might inject + an overload report into the network. If this third party is upstream + of an agent, and that agent fails to apply proper authorization + policies, downstream nodes may mistakenly trust the report. This + attack is at least partially mitigated by the assumption that nodes + include overload reports in Diameter answers but not in requests. + This requires an attacker to have knowledge of the original request + in order to construct an answer. Such an answer would also need to + arrive at a Diameter node via a protected transport connection. + Therefore, implementations MUST validate that an answer containing an + overload report is a properly constructed response to a pending + request prior to acting on the overload report, and that the answer + was received via an appropriate transport connection. + + A similar attack involves a compromised but otherwise authorized node + that sends an inappropriate overload report. For example, a server + for the realm "example.com" might send an overload report indicating + that a competitor's realm "example.net" is overloaded. If other + nodes act on the report, they may falsely believe that "example.net" + is overloaded, effectively reducing that realm's capacity. + Therefore, it's critical that nodes validate that an overload report + received from a peer actually falls within that peer's responsibility + before acting on the report or forwarding the report to other peers. + For example, an overload report from a peer that applies to a realm + not handled by that peer is suspect. This may require out-of-band, + non-Diameter agreements and/or mechanisms. + + This attack is partially mitigated by the fact that the + application, as well as host and realm, for a given OLR is + determined implicitly by respective AVPs in the enclosing answer. + If a reporting node modifies any of those AVPs, the enclosing + transaction will also be affected. + +10.2. Denial-of-Service Attacks + + Diameter overload reports, especially realm reports, can cause a node + to cease sending some or all Diameter requests for an extended + period. This makes them a tempting vector for DoS attacks. + Furthermore, since Diameter is almost always used in support of other + + + +Korhonen, et al. Standards Track [Page 31] + +RFC 7683 DOIC October 2015 + + + protocols, a DoS attack on Diameter is likely to impact those + protocols as well. In the worst case, where the Diameter application + is being used for access control into an IP network, a coordinated + DoS attack could result in the blockage of all traffic into that + network. Therefore, Diameter nodes MUST NOT honor or forward OLRs + received from peers that are not trusted to send them. + + An attacker might use the information in an OLR to assist in DoS + attacks. For example, an attacker could use information about + current overload conditions to time an attack for maximum effect, or + use subsequent overload reports as a feedback mechanism to learn the + results of a previous or ongoing attack. Operators need the ability + to ensure that OLRs are not leaked to untrusted parties. + +10.3. Noncompliant Nodes + + In the absence of an overload control mechanism, Diameter nodes need + to implement strategies to protect themselves from floods of + requests, and to make sure that a disproportionate load from one + source does not prevent other sources from receiving service. For + example, a Diameter server might throttle a certain percentage of + requests from sources that exceed certain limits. Overload control + can be thought of as an optimization for such strategies, where + downstream nodes never send the excess requests in the first place. + However, the presence of an overload control mechanism does not + remove the need for these other protection strategies. + + When a Diameter node sends an overload report, it cannot assume that + all nodes will comply, even if they indicate support for DOIC. A + noncompliant node might continue to send requests with no reduction + in load. Such noncompliance could be done accidentally or + maliciously to gain an unfair advantage over compliant nodes. + Requirement 28 in [RFC7068] indicates that the overload control + solution cannot assume that all Diameter nodes in a network are + trusted. It also requires that malicious nodes not be allowed to + take advantage of the overload control mechanism to get more than + their fair share of service. + +10.4. End-to-End Security Issues + + The lack of end-to-end integrity features makes it difficult to + establish trust in overload reports received from non-adjacent nodes. + Any agents in the message path may insert or modify overload reports. + Nodes must trust that their adjacent peers perform proper checks on + overload reports from their peers, and so on, creating a transitive- + trust requirement extending for potentially long chains of nodes. + Network operators must determine if this transitive trust requirement + is acceptable for their deployments. Nodes supporting Diameter + + + +Korhonen, et al. Standards Track [Page 32] + +RFC 7683 DOIC October 2015 + + + overload control MUST give operators the ability to select which + peers are trusted to deliver overload reports and whether they are + trusted to forward overload reports from non-adjacent nodes. DOIC + nodes MUST strip DOIC AVPs from messages received from peers that are + not trusted for DOIC purposes. + + The lack of end-to-end confidentiality protection means that any + Diameter Agent in the path of an overload report can view the + contents of that report. In addition to the requirement to select + which peers are trusted to send overload reports, operators MUST be + able to select which peers are authorized to receive reports. A node + MUST NOT send an overload report to a peer not authorized to receive + it. Furthermore, an agent MUST remove any overload reports that + might have been inserted by other nodes before forwarding a Diameter + message to a peer that is not authorized to receive overload reports. + + A DOIC node cannot always automatically detect that a peer also + supports DOIC. For example, a node might have a peer that is a + non-supporting agent. If nodes on the other side of that agent + send OC-Supported-Features AVPs, the agent is likely to forward + them as unknown AVPs. Messages received across the non-supporting + agent may be indistinguishable from messages received across a + DOIC supporting agent, giving the false impression that the non- + supporting agent actually supports DOIC. This complicates the + transitive-trust nature of DOIC. Operators need to be careful to + avoid situations where a non-supporting agent is mistakenly + trusted to enforce DOIC-related authorization policies. + + It is expected that work on end-to-end Diameter security might make + it easier to establish trust in non-adjacent nodes for overload + control purposes. Readers should be reminded, however, that the + overload control mechanism allows Diameter Agents to modify AVPs in, + or insert additional AVPs into, existing messages that are originated + by other nodes. If end-to-end security is enabled, there is a risk + that such modification could violate integrity protection. The + details of using any future Diameter end-to-end security mechanism + with overload control will require careful consideration, and are + beyond the scope of this document. + + + + + + + + + + + + + +Korhonen, et al. Standards Track [Page 33] + +RFC 7683 DOIC October 2015 + + +11. References + +11.1. Normative References + + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, + DOI 10.17487/RFC2119, March 1997, + . + + [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an + IANA Considerations Section in RFCs", BCP 26, RFC 5226, + DOI 10.17487/RFC5226, May 2008, + . + + [RFC6733] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn, + Ed., "Diameter Base Protocol", RFC 6733, + DOI 10.17487/RFC6733, October 2012, + . + +11.2. Informative References + + [Cx] 3GPP, "Cx and Dx interfaces based on the Diameter + protocol; Protocol details", 3GPP TS 29.229 12.7.0, + September 2015. + + [PCC] 3GPP, "Policy and charging control architecture", 3GPP + TS 23.203 12.10.0, September 2015. + + [RFC4006] Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J. + Loughney, "Diameter Credit-Control Application", RFC 4006, + DOI 10.17487/RFC4006, August 2005, + . + + [RFC7068] McMurry, E. and B. Campbell, "Diameter Overload Control + Requirements", RFC 7068, DOI 10.17487/RFC7068, November + 2013, . + + [S13] 3GPP, "Evolved Packet System (EPS); Mobility Management + Entity (MME) and Serving GPRS Support Node (SGSN) related + interfaces based on Diameter protocol", 3GPP TS 29.272 + 12.8.0, September 2015. + + + + + + + + + + +Korhonen, et al. Standards Track [Page 34] + +RFC 7683 DOIC October 2015 + + +Appendix A. Issues Left for Future Specifications + + The base solution for overload control does not cover all possible + use cases. A number of solution aspects were intentionally left for + future specification and protocol work. The following subsections + define some of the potential extensions to the DOIC solution. + +A.1. Additional Traffic Abatement Algorithms + + This specification describes only means for a simple loss-based + algorithm. Future algorithms can be added using the designed + solution extension mechanism. The new algorithms need to be + registered with IANA. See Sections 7.2 and 9 for the required IANA + steps. + +A.2. Agent Overload + + This specification focuses on Diameter endpoint (server or client) + overload. A separate extension will be required to outline the + handling of the case of agent overload. + +A.3. New Error Diagnostic AVP + + This specification indicates the use of existing error messages when + nodes reject requests due to overload. There is an expectation that + additional error codes or AVPs will be defined in a separate + specification to indicate that overload was the reason for the + rejection of the message. + +Appendix B. Deployment Considerations + + Non-supporting Agents + + Due to the way that realm-routed requests are handled in Diameter + networks with the server selection for the request done by an + agent, network operators should enable DOIC at agents that perform + server selection first. + + Topology-Hiding Interactions + + There exist proxies that implement what is referred to as Topology + Hiding. This can include cases where the agent modifies the + Origin-Host in answer messages. The behavior of the DOIC solution + is not well understood when this happens. As such, the DOIC + solution does not address this scenario. + + + + + + +Korhonen, et al. Standards Track [Page 35] + +RFC 7683 DOIC October 2015 + + + Inter-Realm/Administrative Domain Considerations + + There are likely to be special considerations for handling DOIC + signaling across administrative boundaries. This includes + considerations for whether or not information included in the DOIC + signaling should be sent across those boundaries. In addition, + consideration should be taken as to whether or not a reacting node + in one realm can be trusted to implement the requested overload + abatement handling for overload reports received from a separately + administered realm. + +Appendix C. Considerations for Applications Integrating the DOIC + Solution + + This section outlines considerations to be taken into account when + integrating the DOIC solution into Diameter applications. + +C.1. Application Classification + + The following is a classification of Diameter applications and + request types. This discussion is meant to document factors that + play into decisions made by the Diameter entity responsible for + handling overload reports. + + Section 8.1 of [RFC6733] defines two state machines that imply two + types of applications, session-less and session-based applications. + The primary difference between these types of applications is the + lifetime of Session-Ids. + + For session-based applications, the Session-Id is used to tie + multiple requests into a single session. + + The Credit-Control application defined in [RFC4006] is an example of + a Diameter session-based application. + + In session-less applications, the lifetime of the Session-Id is a + single Diameter transaction, i.e., the session is implicitly + terminated after a single Diameter transaction and a new Session-Id + is generated for each Diameter request. + + + + + + + + + + + + +Korhonen, et al. Standards Track [Page 36] + +RFC 7683 DOIC October 2015 + + + For the purposes of this discussion, session-less applications are + further divided into two types of applications: + + Stateless Applications: + + Requests within a stateless application have no relationship to + each other. The 3GPP-defined S13 application is an example of a + stateless application [S13], where only a Diameter command is + defined between a client and a server and no state is maintained + between two consecutive transactions. + + Pseudo-Session Applications: + + Applications that do not rely on the Session-Id AVP for + correlation of application messages related to the same session + but use other session-related information in the Diameter requests + for this purpose. The 3GPP-defined Cx application [Cx] is an + example of a pseudo-session application. + + The handling of overload reports must take the type of application + into consideration, as discussed in Appendix C.2. + +C.2. Implications of Application Type Overload + + This section discusses considerations for mitigating overload + reported by a Diameter entity. This discussion focuses on the type + of application. Appendix C.3 discusses considerations for handling + various request types when the target server is known to be in an + overloaded state. + + These discussions assume that the strategy for mitigating the + reported overload is to reduce the overall workload sent to the + overloaded entity. The concept of applying overload treatment to + requests targeted for an overloaded Diameter entity is inherent to + this discussion. The method used to reduce offered load is not + specified here, but it could include routing requests to another + Diameter entity known to be able to handle them, or it could mean + rejecting certain requests. For a Diameter Agent, rejecting requests + will usually mean generating appropriate Diameter error responses. + For a Diameter client, rejecting requests will depend upon the + application. For example, it could mean giving an indication to the + entity requesting the Diameter service that the network is busy and + to try again later. + + + + + + + + +Korhonen, et al. Standards Track [Page 37] + +RFC 7683 DOIC October 2015 + + + Stateless Applications: + + By definition, there is no relationship between individual + requests in a stateless application. As a result, when a request + is sent or relayed to an overloaded Diameter entity -- either a + Diameter Server or a Diameter Agent -- the sending or relaying + entity can choose to apply the overload treatment to any request + targeted for the overloaded entity. + + Pseudo-session Applications: + + For pseudo-session applications, there is an implied ordering of + requests. As a result, decisions about which requests towards an + overloaded entity to reject could take the command code of the + request into consideration. This generally means that + transactions later in the sequence of transactions should be given + more favorable treatment than messages earlier in the sequence. + This is because more work has already been done by the Diameter + network for those transactions that occur later in the sequence. + Rejecting them could result in increasing the load on the network + as the transactions earlier in the sequence might also need to be + repeated. + + Session-Based Applications: + + Overload handling for session-based applications must take into + consideration the work load associated with setting up and + maintaining a session. As such, the entity sending requests + towards an overloaded Diameter entity for a session-based + application might tend to reject new session requests prior to + rejecting intra-session requests. In addition, session-ending + requests might be given a lower probability of being rejected, as + rejecting session-ending requests could result in session status + being out of sync between the Diameter clients and servers. + Application designers that would decide to reject mid-session + requests will need to consider whether the rejection invalidates + the session and any resulting session cleanup procedures. + +C.3. Request Transaction Classification + + Independent Request: + + An independent request is not correlated to any other requests, + and, as such, the lifetime of the Session-Id is constrained to an + individual transaction. + + + + + + +Korhonen, et al. Standards Track [Page 38] + +RFC 7683 DOIC October 2015 + + + Session-Initiating Request: + + A session-initiating request is the initial message that + establishes a Diameter session. The ACR message defined in + [RFC6733] is an example of a session-initiating request. + + Correlated Session-Initiating Request: + + There are cases when multiple session-initiated requests must be + correlated and managed by the same Diameter server. It is notably + the case in the 3GPP Policy and Charging Control (PCC) + architecture [PCC], where multiple apparently independent Diameter + application sessions are actually correlated and must be handled + by the same Diameter server. + + Intra-session Request: + + An intra-session request is a request that uses the same Session- + Id as the one used in a previous request. An intra-session + request generally needs to be delivered to the server that handled + the session-creating request for the session. The STR message + defined in [RFC6733] is an example of an intra-session request. + + Pseudo-session Requests: + + Pseudo-session requests are independent requests and do not use + the same Session-Id but are correlated by other session-related + information contained in the request. There exist Diameter + applications that define an expected ordering of transactions. + This sequencing of independent transactions results in a pseudo- + session. The AIR, MAR, and SAR requests in the 3GPP-defined Cx + [Cx] application are examples of pseudo-session requests. + +C.4. Request Type Overload Implications + + The request classes identified in Appendix C.3 have implications on + decisions about which requests should be throttled first. The + following list of request treatments regarding throttling is provided + as guidelines for application designers when implementing the + Diameter overload control mechanism described in this document. The + exact behavior regarding throttling is a matter of local policy, + unless specifically defined for the application. + + Independent Requests: + + Independent requests can generally be given equal treatment when + making throttling decisions, unless otherwise indicated by + application requirements or local policy. + + + +Korhonen, et al. Standards Track [Page 39] + +RFC 7683 DOIC October 2015 + + + Session-Initiating Requests: + + Session-initiating requests often represent more work than + independent or intra-session requests. Moreover, session- + initiating requests are typically followed by other session- + related requests. Since the main objective of overload control is + to reduce the total number of requests sent to the overloaded + entity, throttling decisions might favor allowing intra-session + requests over session-initiating requests. In the absence of + local policies or application-specific requirements to the + contrary, individual session-initiating requests can be given + equal treatment when making throttling decisions. + + Correlated Session-Initiating Requests: + + A request that results in a new binding; where the binding is used + for routing of subsequent session-initiating requests to the same + server, it represents more work load than other requests. As + such, these requests might be throttled more frequently than other + request types. + + Pseudo-session Requests: + + Throttling decisions for pseudo-session requests can take into + consideration where individual requests fit into the overall + sequence of requests within the pseudo-session. Requests that are + earlier in the sequence might be throttled more aggressively than + requests that occur later in the sequence. + + Intra-session Requests: + + There are two types of intra-sessions requests, requests that + terminate a session and the remainder of intra-session requests. + Implementers and operators may choose to throttle session- + terminating requests less aggressively in order to gracefully + terminate sessions, allow cleanup of the related resources (e.g., + session state), and avoid the need for additional intra-session + requests. Favoring session termination requests may reduce the + session management impact on the overloaded entity. The default + handling of other intra-session requests might be to treat them + equally when making throttling decisions. There might also be + application-level considerations whether some request types are + favored over others. + + + + + + + + +Korhonen, et al. Standards Track [Page 40] + +RFC 7683 DOIC October 2015 + + +Contributors + + The following people contributed substantial ideas, feedback, and + discussion to this document: + + o Eric McMurry + + o Hannes Tschofenig + + o Ulrich Wiehe + + o Jean-Jacques Trottin + + o Maria Cruz Bartolome + + o Martin Dolly + + o Nirav Salot + + o Susan Shishufeng + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Korhonen, et al. Standards Track [Page 41] + +RFC 7683 DOIC October 2015 + + +Authors' Addresses + + Jouni Korhonen (editor) + Broadcom Corporation + 3151 Zanker Road + San Jose, CA 95134 + United States + + Email: jouni.nospam@gmail.com + + + Steve Donovan (editor) + Oracle + 7460 Warren Parkway + Frisco, Texas 75034 + United States + + Email: srdonovan@usdonovans.com + + + Ben Campbell + Oracle + 7460 Warren Parkway + Frisco, Texas 75034 + United States + + Email: ben@nostrum.com + + + Lionel Morand + Orange Labs + 38/40 rue du General Leclerc + Issy-Les-Moulineaux Cedex 9 92794 + France + + Phone: +33145296257 + Email: lionel.morand@orange.com + + + + + + + + + + + + + + +Korhonen, et al. Standards Track [Page 42] + diff --git a/lib/diameter/src/Makefile b/lib/diameter/src/Makefile index 6bf748a727..3af856f63e 100644 --- a/lib/diameter/src/Makefile +++ b/lib/diameter/src/Makefile @@ -1,7 +1,7 @@ # # %CopyrightBegin% # -# Copyright Ericsson AB 2010-2016. All Rights Reserved. +# Copyright Ericsson AB 2010-2017. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. @@ -274,9 +274,7 @@ gen/diameter_gen_base_accounting.erl gen/diameter_gen_base_accounting.hrl: \ gen/diameter_gen_acct_rfc6733.erl gen/diameter_gen_acct_rfc6733.hrl: \ $(EBIN)/diameter_gen_base_rfc6733.$(EMULATOR) -gen/diameter_gen_relay.erl gen/diameter_gen_relay.hrl \ -gen/diameter_gen_base_rfc3588.erl gen/diameter_gen_base_rfc3588.hrl \ -gen/diameter_gen_base_rfc6733.erl gen/diameter_gen_base_rfc6733.hrl: \ +$(DICT_ERLS) $(DICT_HRLS): \ $(COMPILER_MODULES:%=$(EBIN)/%.$(EMULATOR)) $(DICT_MODULES:gen/%=$(EBIN)/%.$(EMULATOR)): \ diff --git a/lib/diameter/src/dict/doic_rfc7683.dia b/lib/diameter/src/dict/doic_rfc7683.dia new file mode 100644 index 0000000000..2b7804115e --- /dev/null +++ b/lib/diameter/src/dict/doic_rfc7683.dia @@ -0,0 +1,50 @@ +;; +;; %CopyrightBegin% +;; +;; Copyright Ericsson AB 2017. All Rights Reserved. +;; +;; Licensed under the Apache License, Version 2.0 (the "License"); +;; you may not use this file except in compliance with the License. +;; You may obtain a copy of the License at +;; +;; http://www.apache.org/licenses/LICENSE-2.0 +;; +;; Unless required by applicable law or agreed to in writing, software +;; distributed under the License is distributed on an "AS IS" BASIS, +;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +;; See the License for the specific language governing permissions and +;; limitations under the License. +;; +;; %CopyrightEnd% +;; + +@name diameter_gen_doic_rfc7683 +@prefix diameter_doic + +@avp_types + + OC-Supported-Features 621 Grouped - + OC-Feature-Vector 622 Unsigned64 - + OC-OLR 623 Grouped - + OC-Sequence-Number 624 Unsigned64 - + OC-Validity-Duration 625 Unsigned32 - + OC-Report-Type 626 Enumerated - + OC-Reduction-Percentage 627 Unsigned32 - + +@enum OC-Report-Type + + HOST_REPORT 0 + REALM_REPORT 1 + +@grouped + + OC-Supported-Features ::= < AVP Header: 621 > + [ OC-Feature-Vector ] + * [ AVP ] + + OC-OLR ::= < AVP Header: 623 > + < OC-Sequence-Number > + < OC-Report-Type > + [ OC-Reduction-Percentage ] + [ OC-Validity-Duration ] + * [ AVP ] diff --git a/lib/diameter/src/modules.mk b/lib/diameter/src/modules.mk index bb3b234d20..bb86de016a 100644 --- a/lib/diameter/src/modules.mk +++ b/lib/diameter/src/modules.mk @@ -24,6 +24,7 @@ DICTS = \ base_rfc6733 \ base_accounting \ acct_rfc6733 \ + doic_rfc7683 \ relay # The yecc grammar for the dictionary parser. diff --git a/lib/diameter/test/diameter_codec_test.erl b/lib/diameter/test/diameter_codec_test.erl index 22fb0550ea..d7cb6f0105 100644 --- a/lib/diameter/test/diameter_codec_test.erl +++ b/lib/diameter/test/diameter_codec_test.erl @@ -44,7 +44,8 @@ base() -> [] = run([[fun base/1, T] || T <- [zero, decode]]). gen(Mod) -> - Fs = [{Mod, F, []} || F <- [name, id, vendor_id, vendor_name]], + Fs = [{Mod, F, []} || Mod /= diameter_gen_doic_rfc7683, + F <- [name, id, vendor_id, vendor_name]], [] = run(Fs ++ [[fun gen/2, Mod, T] || T <- [messages, command_codes, avp_types, -- cgit v1.2.3 From 382c88e5fdb92c6f97acad2f1c260cc69759b8e5 Mon Sep 17 00:00:00 2001 From: Anders Svensson Date: Fri, 1 Sep 2017 17:37:24 +0200 Subject: Rename field in codec map: dictionary -> app_dictionary To better reflect what the field is: field 'module' is the dictionary module that's calling diameter_gen to decode a list of AVP, while field 'app_dictionary' is the dictionary module defining the message being decoded. --- lib/diameter/src/base/diameter_codec.erl | 2 +- lib/diameter/src/base/diameter_gen.erl | 2 +- lib/diameter/src/base/diameter_traffic.erl | 2 +- lib/diameter/test/diameter_codec_SUITE.erl | 2 +- lib/diameter/test/diameter_codec_SUITE_data/diameter_test_unknown.erl | 2 +- lib/diameter/test/diameter_codec_test.erl | 2 +- 6 files changed, 6 insertions(+), 6 deletions(-) diff --git a/lib/diameter/src/base/diameter_codec.erl b/lib/diameter/src/base/diameter_codec.erl index 63e39b12d1..4f024f9947 100644 --- a/lib/diameter/src/base/diameter_codec.erl +++ b/lib/diameter/src/base/diameter_codec.erl @@ -324,7 +324,7 @@ decode_avps(MsgName, Mod, AppMod, Opts, #diameter_packet{bin = Bin} = Pkt) -> {_, Avps} = split_binary(Bin, 20), {Rec, As, Errors} = Mod:decode_avps(MsgName, Avps, - Opts#{dictionary => AppMod, + Opts#{app_dictionary => AppMod, failed_avp => false}), ?LOGC([] /= Errors, decode_errors, Pkt#diameter_packet.header), Pkt#diameter_packet{msg = reformat(MsgName, Rec, Opts), diff --git a/lib/diameter/src/base/diameter_gen.erl b/lib/diameter/src/base/diameter_gen.erl index 307c3b4254..1c699f6be6 100644 --- a/lib/diameter/src/base/diameter_gen.erl +++ b/lib/diameter/src/base/diameter_gen.erl @@ -503,7 +503,7 @@ decode1(_Data, _Name, 'AVP', _Mod, _Fmt, _Opts, Avp) -> %% "not defined".) decode1(Data, Name, {AvpName, Type}, Mod, Fmt, Opts, Avp) -> - #{dictionary := AppMod, failed_avp := Failed} + #{app_dictionary := AppMod, failed_avp := Failed} = Opts, %% Reset the dictionary for best-effort decode of Failed-AVP. diff --git a/lib/diameter/src/base/diameter_traffic.erl b/lib/diameter/src/base/diameter_traffic.erl index 3cc1c7cce5..5a51494274 100644 --- a/lib/diameter/src/base/diameter_traffic.erl +++ b/lib/diameter/src/base/diameter_traffic.erl @@ -2020,4 +2020,4 @@ decode_opts(Dict) -> strict_mbit => false, failed_avp => false, module => Dict, - dictionary => Dict}. + app_dictionary => Dict}. diff --git a/lib/diameter/test/diameter_codec_SUITE.erl b/lib/diameter/test/diameter_codec_SUITE.erl index c79b642c09..17112794e4 100644 --- a/lib/diameter/test/diameter_codec_SUITE.erl +++ b/lib/diameter/test/diameter_codec_SUITE.erl @@ -291,7 +291,7 @@ recode(Msg, Dict) -> recode(#diameter_packet{msg = Msg}, Dict). opts(Mod) -> - #{dictionary => Mod, + #{app_dictionary => Mod, decode_format => record, string_decode => false, strict_mbit => true, diff --git a/lib/diameter/test/diameter_codec_SUITE_data/diameter_test_unknown.erl b/lib/diameter/test/diameter_codec_SUITE_data/diameter_test_unknown.erl index 735339ebb9..c6bba75f09 100644 --- a/lib/diameter/test/diameter_codec_SUITE_data/diameter_test_unknown.erl +++ b/lib/diameter/test/diameter_codec_SUITE_data/diameter_test_unknown.erl @@ -77,7 +77,7 @@ dec('BR', #diameter_packet ok. opts(Mod) -> - #{dictionary => Mod, + #{app_dictionary => Mod, decode_format => record, string_decode => true, strict_mbit => true, diff --git a/lib/diameter/test/diameter_codec_test.erl b/lib/diameter/test/diameter_codec_test.erl index d7cb6f0105..70e910ffa6 100644 --- a/lib/diameter/test/diameter_codec_test.erl +++ b/lib/diameter/test/diameter_codec_test.erl @@ -217,7 +217,7 @@ avp(Mod, encode = X, V, Name, _) -> opts(Mod) -> (opts())#{module => Mod, - dictionary => Mod}. + app_dictionary => Mod}. opts() -> #{decode_format => record, -- cgit v1.2.3 From 2a25b1f4a45430a2df973f3c632b5aae703d9b81 Mon Sep 17 00:00:00 2001 From: Anders Svensson Date: Sat, 2 Sep 2017 16:17:47 +0200 Subject: Let generic AVPs be encoded/decoded in alternate dictionaries To support specifications like RFC 7683 DOIC, that only define AVPs, not applications. AVPs that aren't known to the application dictionary in question could previously not be decoded. Configuring alternate dictionaries with the new transport/service option avp_dictionaries changes this, so that AVPs like DOIC's Grouped OC-OLR can presented in their fully decoded glory. Encode is also extended, allowing things like the following to be encoded in an outgoing message: 'AVP' => [{'OC-OLR', #{'OC-Sequence-Number' => 1, 'OC-Report-Type' => 0, 'OC-Reduction-Percentage' => [25]}}] A diameter_gen_doic_rfc7683 dictionary is installed, but avp_dictionaries isn't specific to DOIC. This commit also solves the problem demonstrated a few commits back, that application AVPs aren't decoded in answers setting the E-bit. Test coverage will come in a subsequent commit. --- lib/diameter/doc/src/diameter.xml | 31 ++++ lib/diameter/src/base/diameter.erl | 1 + lib/diameter/src/base/diameter_codec.erl | 4 +- lib/diameter/src/base/diameter_config.erl | 3 + lib/diameter/src/base/diameter_gen.erl | 247 +++++++++++++++++++---------- lib/diameter/src/base/diameter_service.erl | 5 +- lib/diameter/src/base/diameter_traffic.erl | 4 + 7 files changed, 207 insertions(+), 88 deletions(-) diff --git a/lib/diameter/doc/src/diameter.xml b/lib/diameter/doc/src/diameter.xml index 0169afb619..6b84b22eb5 100644 --- a/lib/diameter/doc/src/diameter.xml +++ b/lib/diameter/doc/src/diameter.xml @@ -1082,6 +1082,37 @@ implies having to set matching *-Application-Id AVPs in a + +{avp_dictionaries, [module()]} + +

+A list of alternate dictionary modules with which to encode/decode +AVPs that are not defined by the dictionary of the application in +question. +At decode, such AVPs are represented as diameter_avp records in the +'AVP' field of a decoded message or Grouped AVP, the first +alternate that succeeds in decoding the AVP setting the record's value +field. +At encode, values in an 'AVP' list can be passed as AVP +name/value 2-tuples, and it is an encode error for no alternate to +define the AVP of such a tuple.

+ +

+Defaults to the empty list.

+ + +

+The motivation for alternate dictionaries is RFC 7683, Diameter +Overload Indication Conveyance (DOIC), which defines AVPs to +be piggybacked onto existing application messages rather than defining +an application of its own. +The DOIC dictionary is provided by the diameter application, as module +diameter_gen_doic_rfc7683, but alternate dictionaries can be +used to encode/decode any set of AVPs not known to an application +dictionary.

+ + + {capabilities, [&capability;]} diff --git a/lib/diameter/src/base/diameter.erl b/lib/diameter/src/base/diameter.erl index 69ef6f4ec0..b90b794611 100644 --- a/lib/diameter/src/base/diameter.erl +++ b/lib/diameter/src/base/diameter.erl @@ -356,6 +356,7 @@ call(SvcName, App, Message) -> | {capx_timeout, 'Unsigned32'()} | {strict_capx, boolean()} | {strict_mbit, boolean()} + | {avp_dictionaries, [module()]} | {disconnect_cb, eval()} | {dpr_timeout, 'Unsigned32'()} | {dpa_timeout, 'Unsigned32'()} diff --git a/lib/diameter/src/base/diameter_codec.erl b/lib/diameter/src/base/diameter_codec.erl index 4f024f9947..2dd2c906a2 100644 --- a/lib/diameter/src/base/diameter_codec.erl +++ b/lib/diameter/src/base/diameter_codec.erl @@ -614,8 +614,8 @@ pack_avp(#diameter_avp{data = {T, {Type, Value}}}, Opts) -> pack_avp(#diameter_avp{data = {T, Data}}, _) -> pack_data(T, Data); -pack_avp(#diameter_avp{data = {Dict, Name, Data}}, Opts) -> - pack_data(Dict:avp_header(Name), Dict:avp(encode, Data, Name, Opts)); +pack_avp(#diameter_avp{data = {Dict, Name, Value}}, Opts) -> + pack_data(Dict:avp_header(Name), Dict:avp(encode, Value, Name, Opts)); %% ... with a truncated header ... pack_avp(#diameter_avp{code = undefined, data = B}, _) diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl index 284f885884..90a9282349 100644 --- a/lib/diameter/src/base/diameter_config.erl +++ b/lib/diameter/src/base/diameter_config.erl @@ -682,6 +682,9 @@ opt(_, {K, B}) K == strict_mbit -> is_boolean(B); +opt(_, {avp_dictionaries, Mods}) -> + is_list(Mods) andalso lists:all(fun erlang:is_atom/1, Mods); + opt(_, {length_errors, T}) -> lists:member(T, [exit, handle, discard]); diff --git a/lib/diameter/src/base/diameter_gen.erl b/lib/diameter/src/base/diameter_gen.erl index 1c699f6be6..6add06ea38 100644 --- a/lib/diameter/src/base/diameter_gen.erl +++ b/lib/diameter/src/base/diameter_gen.erl @@ -100,73 +100,73 @@ encode(Name, Vals, Opts, Strict, Mod) encode(Name, Map, Opts, Strict, Mod) when is_map(Map) -> - [enc(Name, F, A, V, Opts, Strict, Mod) || {F,A} <- Mod:avp_arity(Name), - V <- [mget(F, Map, undefined)]]; + [enc(F, A, V, Opts, Strict, Mod) || {F,A} <- Mod:avp_arity(Name), + V <- [mget(F, Map, undefined)]]; encode(Name, Rec, Opts, Strict, Mod) -> [encode(Name, F, V, Opts, Strict, Mod) || {F,V} <- Mod:'#get-'(Rec)]. %% encode/6 -encode(Name, AvpName, Values, Opts, Strict, Mod) +encode(_, AvpName, Values, Opts, Strict, Mod) when Strict /= encode -> - enc(Name, AvpName, ?ANY, Values, Opts, Strict, Mod); + enc(AvpName, ?ANY, Values, Opts, Strict, Mod); encode(Name, AvpName, Values, Opts, Strict, Mod) -> Arity = Mod:avp_arity(Name, AvpName), - enc(Name, AvpName, Arity, Values, Opts, Strict, Mod). + enc(AvpName, Arity, Values, Opts, Strict, Mod). -%% enc/7 +%% enc/6 -enc(Name, AvpName, Arity, Values, Opts, Strict, Mod) +enc(AvpName, Arity, Values, Opts, Strict, Mod) when Strict /= encode, Arity /= ?ANY -> - enc(Name, AvpName, ?ANY, Values, Opts, Strict, Mod); + enc(AvpName, ?ANY, Values, Opts, Strict, Mod); -enc(_, AvpName, 1, undefined, _, _, _) -> +enc(AvpName, 1, undefined, _, _, _) -> ?THROW([mandatory_avp_missing, AvpName]); -enc(Name, AvpName, 1, Value, Opts, _, Mod) -> +enc(AvpName, 1, Value, Opts, _, Mod) -> H = avp_header(AvpName, Mod), - enc1(Name, AvpName, H, Value, Opts, Mod); + enc(AvpName, H, Value, Opts, Mod); -enc(_, _, {0,_}, [], _, _, _) -> +enc(_, {0,_}, [], _, _, _) -> []; -enc(_, _, _, undefined, _, _, _) -> +enc(_, _, undefined, _, _, _) -> []; %% Be forgiving when a list of values is expected. If the value itself %% is a list then the user has to wrap it to avoid each member from %% being interpreted as an individual AVP value. -enc(Name, AvpName, Arity, V, Opts, Strict, Mod) +enc(AvpName, Arity, V, Opts, Strict, Mod) when not is_list(V) -> - enc(Name, AvpName, Arity, [V], Opts, Strict, Mod); + enc(AvpName, Arity, [V], Opts, Strict, Mod); -enc(Name, AvpName, {Min, Max}, Values, Opts, Strict, Mod) -> +enc(AvpName, {Min, Max}, Values, Opts, Strict, Mod) -> H = avp_header(AvpName, Mod), - enc(Name, AvpName, H, Min, 0, Max, Values, Opts, Strict, Mod). + enc(AvpName, H, Min, 0, Max, Values, Opts, Strict, Mod). -%% enc/10 +%% enc/9 -enc(Name, AvpName, H, Min, N, Max, Vs, Opts, Strict, Mod) +enc(AvpName, H, Min, N, Max, Vs, Opts, Strict, Mod) when Strict /= encode; Max == '*', Min =< N -> - [enc1(Name, AvpName, H, V, Opts, Mod) || V <- Vs]; + [enc(AvpName, H, V, Opts, Mod) || V <- Vs]; -enc(_, AvpName, _, Min, N, _, [], _, _, _) +enc(AvpName, _, Min, N, _, [], _, _, _) when N < Min -> ?THROW([repeated_avp_insufficient_arity, AvpName, Min, N]); -enc(_, _, _, _, _, _, [], _, _, _) -> +enc(_, _, _, _, _, [], _, _, _) -> []; -enc(_, AvpName, _, _, N, Max, _, _, _, _) +enc(AvpName, _, _, N, Max, _, _, _, _) when Max =< N -> ?THROW([repeated_avp_excessive_arity, AvpName, Max]); -enc(Name, AvpName, H, Min, N, Max, [V|Vs], Opts, Strict, Mod) -> - [enc1(Name, AvpName, H, V, Opts, Mod) - | enc(Name, AvpName, H, Min, N+1, Max, Vs, Opts, Strict, Mod)]. +enc(AvpName, H, Min, N, Max, [V|Vs], Opts, Strict, Mod) -> + [enc(AvpName, H, V, Opts, Mod) + | enc(AvpName, H, Min, N+1, Max, Vs, Opts, Strict, Mod)]. %% avp_header/2 @@ -176,12 +176,12 @@ avp_header('AVP', _) -> avp_header(AvpName, Mod) -> {_,_,_} = Mod:avp_header(AvpName). -%% enc1/6 +%% enc/5 -enc1(Name, 'AVP', false, Value, Opts, Mod) -> - enc_AVP(Name, Value, Opts, Mod); +enc('AVP', false, Value, Opts, Mod) -> + enc_AVP(Value, Opts, Mod); -enc1(_, AvpName, Hdr, Value, Opts, Mod) -> +enc(AvpName, Hdr, Value, Opts, Mod) -> enc1(AvpName, Hdr, Value, Opts, Mod). %% enc1/5 @@ -189,41 +189,59 @@ enc1(_, AvpName, Hdr, Value, Opts, Mod) -> enc1(AvpName, {_,_,_} = Hdr, Value, Opts, Mod) -> diameter_codec:pack_data(Hdr, Mod:avp(encode, Value, AvpName, Opts)). -%% enc_AVP/4 +%% enc1/6 + +enc1(AvpName, {_,_,_} = Hdr, Value, Opts, Mod, Dict) -> + diameter_codec:pack_data(Hdr, avp(encode, Value, AvpName, Opts, Mod, Dict)). + +%% enc_AVP/3 %% No value: assume AVP data is already encoded. The normal case will %% be when this is passed back from #diameter_packet.errors as a %% consequence of a failed decode. Any AVP can be encoded this way %% however, which side-steps any arity checks for known AVP's and %% could potentially encode something unfortunate. -enc_AVP(_, #diameter_avp{value = undefined} = A, Opts, _) -> +enc_AVP(#diameter_avp{value = undefined} = A, Opts, _) -> diameter_codec:pack_avp(A, Opts); -%% Missing name for value encode. -enc_AVP(_, #diameter_avp{name = N, value = V}, _, _) - when N == undefined; - N == 'AVP' -> - ?THROW([value_with_nameless_avp, N, V]); +%% Encode a name/value pair using an alternate dictionary if need be ... +enc_AVP(#diameter_avp{name = AvpName, value = Value}, Opts, Mod) -> + enc_AVP(AvpName, Value, Opts, Mod); +enc_AVP({AvpName, Value}, Opts, Mod) -> + enc_AVP(AvpName, Value, Opts, Mod); + +%% ... or with a specified dictionary. +enc_AVP({Dict, AvpName, Value}, Opts, Mod) -> + enc1(AvpName, Dict:avp_header(AvpName), Value, Opts, Mod, Dict). -%% Or not. Ensure that 'AVP' is the appropriate field. Note that if we -%% don't know this AVP at all then the encode will fail. -enc_AVP(Name, #diameter_avp{name = AvpName, value = Data}, Opts, Mod) -> - 0 == Mod:avp_arity(Name, AvpName) - orelse ?THROW([known_avp_as_AVP, Name, AvpName, Data]), - enc(AvpName, Data, Opts, Mod); +%% Don't guard against anything being sent as a generic 'AVP', which +%% allows arity restrictions to be abused. + +%% enc_AVP/4 -%% The backdoor ... -enc_AVP(_, {AvpName, Value}, Opts, Mod) -> - enc(AvpName, Value, Opts, Mod); +enc_AVP(AvpName, Value, Opts, Mod) -> + try Mod:avp_header(AvpName) of + H -> + enc1(AvpName, H, Value, Opts, Mod) + catch + error: _ -> + Dicts = mget(avp_dictionaries, Opts, []), + enc_AVP(Dicts, AvpName, Value, Opts, Mod) + end. -%% ... and the side door. -enc_AVP(_Name, {_Dict, _AvpName, _Data} = T, Opts, _) -> - diameter_codec:pack_avp(#diameter_avp{data = T}, Opts). +%% enc_AVP/5 -%% enc/4 +enc_AVP([Dict | Rest], AvpName, Value, Opts, Mod) -> + try Dict:avp_header(AvpName) of + H -> + enc1(AvpName, H, Value, Opts, Mod, Dict) + catch + error: _ -> + enc_AVP(Rest, AvpName, Value, Opts, Mod) + end; -enc(AvpName, Value, Opts, Mod) -> - enc1(AvpName, Mod:avp_header(AvpName), Value, Opts, Mod). +enc_AVP([], AvpName, _, _, _) -> + ?THROW([no_dictionary, AvpName]). %% --------------------------------------------------------------------------- %% # decode_avps/3 @@ -301,9 +319,9 @@ decode(Bin, Code, Vid, DataLen, Pad, M, P, Name, Mod, Fmt, Strict, Opts0, type = type(NameT), index = Idx}, - Dec = decode1(Data, Name, NameT, Mod, Fmt, Opts, Avp), + Dec = dec(Data, Name, NameT, Mod, Fmt, Opts, Avp), Acc = decode(T, Name, Mod, Fmt, Strict, Opts, Idx+1, AM),%% recurse - acc(Acc, Dec, I, Name, Field, Arity, Strict, Mod, Opts); + acc(Acc, Dec, I, Field, Arity, Strict, Mod, Opts); _ -> {NameT, _Field, _Arity, {_, AM}} = incr(Name, Code, Vid, M, Mod, Strict, Opts0, AM0), @@ -449,12 +467,16 @@ field({AvpName, _}) -> field(_) -> 'AVP'. -%% decode1/7 +%% dec/7 -%% AVP not in dictionary. -decode1(_Data, _Name, 'AVP', _Mod, _Fmt, _Opts, Avp) -> +%% AVP not in dictionary: try an alternate. + +dec(_, _, 'AVP', _Mod, none, _, Avp) -> %% none decode is no-op Avp; +dec(Data, Name, 'AVP', Mod, Fmt, Opts, Avp) -> + dec_AVP(dicts(Mod, Opts), Data, Name, Mod, Fmt, Opts, Avp); + %% 6733, 4.4: %% %% Receivers of a Grouped AVP that does not have the 'M' (mandatory) @@ -502,20 +524,35 @@ decode1(_Data, _Name, 'AVP', _Mod, _Fmt, _Opts, Avp) -> %% defined the RFC's "unrecognized", which is slightly stronger than %% "not defined".) -decode1(Data, Name, {AvpName, Type}, Mod, Fmt, Opts, Avp) -> +dec(Data, Name, {AvpName, Type}, Mod, Fmt, Opts, Avp) -> #{app_dictionary := AppMod, failed_avp := Failed} = Opts, %% Reset the dictionary for best-effort decode of Failed-AVP. - DecMod = if Failed -> AppMod; - true -> Mod - end, + Dict = if Failed -> AppMod; + true -> Mod + end, + + dec(Data, Name, AvpName, Type, Mod, Dict, Fmt, Failed, Opts, Avp). + +%% dicts/2 - %% A Grouped AVP is represented as a #diameter_avp{} list with AVP - %% as head and component AVPs as tail. On encode, data can be a - %% list of component AVPs. +dicts(Mod, #{app_dictionary := Mod, avp_dictionaries := Dicts}) -> + Dicts; - try avp_decode(Data, AvpName, Opts, DecMod, Mod) of +dicts(_, #{app_dictionary := Dict, avp_dictionaries := Dicts}) -> + [Dict | Dicts]; + +dicts(Mod, #{app_dictionary := Mod}) -> + []; + +dicts(_, #{app_dictionary := Dict}) -> + [Dict]. + +%% dec/10 + +dec(Data, Name, AvpName, Type, Mod, Dict, Fmt, Failed, Opts, Avp) -> + try avp(decode, Data, AvpName, Opts, Mod, Dict) of V -> set(Type, Fmt, Avp, V) catch @@ -525,7 +562,39 @@ decode1(Data, Name, {AvpName, Type}, Mod, Fmt, Opts, Avp) -> decode_error(Failed, Reason, Name, Mod, Opts, Avp) end. +%% dec_AVP/7 + +dec_AVP([], _, _, _, _, _, Avp) -> + Avp; + +dec_AVP(Dicts, Data, Name, Mod, Fmt, Opts, #diameter_avp{code = Code, + vendor_id = Vid} + = Avp) -> + dec_AVP(Dicts, Data, Name, Mod, Fmt, Opts, Code, Vid, Avp). + +%% dec_AVP/9 +%% +%% Try to decode an AVP in the first alternate dictionary that defines +%% it. + +dec_AVP([Dict | Rest], Data, Name, Mod, Fmt, Opts, Code, Vid, Avp) -> + case Dict:avp_name(Code, Vid) of + {AvpName, Type} -> + A = Avp#diameter_avp{name = AvpName, + type = Type}, + #{failed_avp := Failed} = Opts, + dec(Data, Name, AvpName, Type, Mod, Dict, Fmt, Failed, Opts, A); + _ -> + dec_AVP(Rest, Data, Name, Mod, Fmt, Opts, Code, Vid, Avp) + end; + +dec_AVP([], _, _, _, _, _, _, _, Avp) -> + Avp. + %% set/4 +%% +%% A Grouped AVP is represented as a #diameter_avp{} list with AVP +%% as head and component AVPs as tail. set('Grouped', none, Avp, V) -> {_Rec, As} = V, @@ -566,13 +635,13 @@ decode_error(false, Reason, Name, Mod, Opts, Avp) -> {Reason, Name, Avp#diameter_avp.name, Mod, Stack}), rc(Reason, Avp, Opts, Mod). -%% avp_decode/5 +%% avp/6 -avp_decode(Data, AvpName, Opts, Mod, Mod) -> - Mod:avp(decode, Data, AvpName, Opts); +avp(T, Data, AvpName, Opts, Mod, Mod) -> + Mod:avp(T, Data, AvpName, Opts); -avp_decode(Data, AvpName, Opts, Mod, _) -> - Mod:avp(decode, Data, AvpName, Opts#{module := Mod}). +avp(T, Data, AvpName, Opts, _, Mod) -> + Mod:avp(T, Data, AvpName, Opts#{module := Mod}). %% set_strict/3 %% @@ -595,49 +664,57 @@ set_failed('Failed-AVP', #{failed_avp := false} = Opts) -> set_failed(_, Opts) -> Opts. -%% acc/9 +%% acc/8 -acc([AM | Acc], As, I, Name, Field, Arity, Strict, Mod, Opts) -> - [AM | acc1(Acc, As, I, Name, Field, Arity, Strict, Mod, Opts)]. +acc([AM | Acc], As, I, Field, Arity, Strict, Mod, Opts) -> + [AM | acc1(Acc, As, I, Field, Arity, Strict, Mod, Opts)]. -%% acc1/9 +%% acc1/8 %% Faulty AVP, not grouped. -acc1(Acc, {_RC, Avp} = E, _, _, _, _, _, _, _) -> +acc1(Acc, {_RC, Avp} = E, _, _, _, _, _, _) -> [Avps, Failed | Rec] = Acc, [[Avp | Avps], [E | Failed] | Rec]; %% Faulty component in grouped AVP. -acc1(Acc, {RC, As, Avp}, _, _, _, _, _, _, _) -> +acc1(Acc, {RC, As, Avp}, _, _, _, _, _, _) -> [Avps, Failed | Rec] = Acc, [[As | Avps], [{RC, Avp} | Failed] | Rec]; %% Grouped AVP ... -acc1([Avps | Acc], [Avp|_] = As, I, Name, Field, Arity, Strict, Mod, Opts) -> - [[As|Avps] | acc2(Acc, Avp, I, Name, Field, Arity, Strict, Mod, Opts)]; +acc1([Avps | Acc], [Avp|_] = As, I, Field, Arity, Strict, Mod, Opts) -> + [[As|Avps] | acc2(Acc, Avp, I, Field, Arity, Strict, Mod, Opts)]; %% ... or not. -acc1([Avps | Acc], Avp, I, Name, Field, Arity, Strict, Mod, Opts) -> - [[Avp|Avps] | acc2(Acc, Avp, I, Name, Field, Arity, Strict, Mod, Opts)]. +acc1([Avps | Acc], Avp, I, Field, Arity, Strict, Mod, Opts) -> + [[Avp|Avps] | acc2(Acc, Avp, I, Field, Arity, Strict, Mod, Opts)]. + +%% The component list of a Grouped AVP is discarded when packing into +%% the record (or equivalent): the values in an 'AVP' field are +%% diameter_avp records, not a list of records in the Grouped case, +%% and the decode into the value field is best-effort. The reason is +%% history more than logic: it would probably have made more sense to +%% retain the same structure as in diameter_packet.avps, but an 'AVP' +%% list has always been flat. -%% acc2/9 +%% acc2/8 %% No errors, but nowhere to pack. -acc2(Acc, Avp, _, _, 'AVP', 0, _, _, _) -> +acc2(Acc, Avp, _, 'AVP', 0, _, _, _) -> [Failed | Rec] = Acc, [[{rc(Avp), Avp} | Failed] | Rec]; %% Relaxed arities. -acc2(Acc, Avp, _, _, Field, Arity, Strict, Mod, _) +acc2(Acc, Avp, _, Field, Arity, Strict, Mod, _) when Strict /= decode -> pack(Arity, Field, Avp, Mod, Acc); %% No maximum arity. -acc2(Acc, Avp, _, _, Field, {_,'*'} = Arity, _, Mod, _) -> +acc2(Acc, Avp, _, Field, {_,'*'} = Arity, _, Mod, _) -> pack(Arity, Field, Avp, Mod, Acc); %% Or check. -acc2(Acc, Avp, I, _, Field, Arity, _, Mod, _) -> +acc2(Acc, Avp, I, Field, Arity, _, Mod, _) -> Mx = max_arity(Arity), if Mx =< I -> [Failed | Rec] = Acc, diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl index 1e104f9e65..7cd4d23402 100644 --- a/lib/diameter/src/base/diameter_service.erl +++ b/lib/diameter/src/base/diameter_service.erl @@ -115,6 +115,7 @@ strict_arities => diameter:strict_arities(), strict_mbit := boolean(), decode_format := diameter:decode_format(), + avp_dictionaries => nonempty_list(module()), traffic_counters := boolean(), string_decode := boolean(), capabilities_cb => diameter:evaluable(), @@ -718,7 +719,8 @@ init_peers() -> %% TPid} service_opts(Opts) -> - remove([{strict_arities, true}], + remove([{strict_arities, true}, + {avp_dictionaries, []}], maps:merge(maps:from_list([{monitor, false} | def_opts()]), maps:from_list(Opts))). @@ -735,6 +737,7 @@ def_opts() -> %% defaults on the service map {strict_arities, true}, {strict_mbit, true}, {decode_format, record}, + {avp_dictionaries, []}, {traffic_counters, true}, {string_decode, true}, {spawn_opt, []}]. diff --git a/lib/diameter/src/base/diameter_traffic.erl b/lib/diameter/src/base/diameter_traffic.erl index 5a51494274..a10bf78d6e 100644 --- a/lib/diameter/src/base/diameter_traffic.erl +++ b/lib/diameter/src/base/diameter_traffic.erl @@ -78,6 +78,7 @@ sequence :: diameter:sequence(), counters :: boolean(), codec :: #{decode_format := diameter:decode_format(), + avp_dictionaries => nonempty_list(module()), string_decode := boolean(), strict_arities => diameter:strict_arities(), strict_mbit := boolean(), @@ -107,6 +108,7 @@ make_recvdata([SvcName, PeerT, Apps, SvcOpts | _]) -> sequence = Mask, counters = B, codec = maps:with([decode_format, + avp_dictionaries, string_decode, strict_arities, strict_mbit, @@ -351,6 +353,8 @@ recv_request(Ack, No end. +%% decode/4 + decode(Id, Dict, #recvdata{codec = Opts}, Pkt) -> errors(Id, diameter_codec:decode(Id, Dict, Opts, Pkt)). -- cgit v1.2.3 From eb54c14b3c0ad26c365e6be70256f16fc8e72d70 Mon Sep 17 00:00:00 2001 From: Anders Svensson Date: Mon, 4 Sep 2017 12:23:57 +0200 Subject: Exercise avp_dictionaries in traffic suite As introduced in the parent commit. --- lib/diameter/test/diameter_traffic_SUITE.erl | 31 ++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/lib/diameter/test/diameter_traffic_SUITE.erl b/lib/diameter/test/diameter_traffic_SUITE.erl index b4656562c4..84a8f5bd92 100644 --- a/lib/diameter/test/diameter_traffic_SUITE.erl +++ b/lib/diameter/test/diameter_traffic_SUITE.erl @@ -20,6 +20,7 @@ %% %% Tests of traffic between two Diameter nodes, one client, one server. +%% The traffic isn't meant to be sensible, just to exercise code. %% -module(diameter_traffic_SUITE). @@ -213,6 +214,7 @@ {'Acct-Application-Id', [3]}, %% base accounting {restrict_connections, false}, {string_decode, Grp#group.strings}, + {avp_dictionaries, [diameter_gen_doic_rfc7683]}, {incoming_maxlen, 1 bsl 21} | [{application, [{dictionary, D}, {module, [?MODULE, Grp]}, @@ -616,7 +618,6 @@ result_codes(_Config) -> send_ok(Config) -> Req = ['ACR', {'Accounting-Record-Type', ?EVENT_RECORD}, {'Accounting-Record-Number', 1}], - ['ACA' | #{'Result-Code' := ?SUCCESS, 'Session-Id' := _}] = call(Config, Req). @@ -653,8 +654,21 @@ send_protocol_error(Config) -> Req = ['ACR', {'Accounting-Record-Type', ?EVENT_RECORD}, {'Accounting-Record-Number', 4}], - ?answer_message(?TOO_BUSY) - = call(Config, Req). + ['answer-message' | #{'Result-Code' := ?TOO_BUSY, + 'AVP' := [OLR]}] + = call(Config, Req), + + #diameter_avp{name = 'OC-OLR', + value = #{'OC-Sequence-Number' := 1, + 'OC-Report-Type' := 0, %% HOST_REPORT + 'OC-Reduction-Percentage' := [25], + 'OC-Validity-Duration' := [60], + 'AVP' := [OSF]}} + = OLR, + #diameter_avp{name = 'OC-Supported-Features', + value = #{} = Fs} + = OSF, + 0 = maps:size(Fs). %% Send a 3xxx Experimental-Result in an answer not setting the E-bit %% and missing a Result-Code. @@ -1143,6 +1157,7 @@ to_map(#diameter_packet{header = H, strings = B}) -> Opts = #{decode_format => map, string_decode => B, + avp_dictionaries => [diameter_gen_doic_rfc7683], strict_mbit => true, rfc => 6733}, #diameter_packet{msg = [MsgName | _Map] = Msg} @@ -1708,9 +1723,17 @@ request(['ACR' | #{'Session-Id' := SId, request(['ACR' | #{'Accounting-Record-Number' := 4}], #diameter_caps{origin_host = {OH, _}, origin_realm = {OR, _}}) -> + %% Include a DOIC AVP that will be encoded/decoded because of + %% avp_dictionaries config. + OLR = #{'OC-Sequence-Number' => 1, + 'OC-Report-Type' => 0, %% HOST_REPORT + 'OC-Reduction-Percentage' => [25], + 'OC-Validity-Duration' => [60], + 'AVP' => [{'OC-Supported-Features', []}]}, Ans = ['answer-message', {'Result-Code', ?TOO_BUSY}, {'Origin-Host', OH}, - {'Origin-Realm', OR}], + {'Origin-Realm', OR}, + {'AVP', [{'OC-OLR', OLR}]}], {reply, Ans}; %% send_proxy_info -- cgit v1.2.3