<?xml version="1.0" encoding="latin1" ?> <!DOCTYPE erlref SYSTEM "erlref.dtd"> <erlref> <header> <copyright> <year>2011</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> The contents of this file are subject to the Erlang Public License, Version 1.1, (the "License"); you may not use this file except in compliance with the License. You should have received a copy of the Erlang Public License along with this software. If not, it can be retrieved online at http://www.erlang.org/. Software distributed under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the specific language governing rights and limitations under the License. </legalnotice> <title>diameter_transport(3)</title> <prepared>Anders Svensson</prepared> <responsible></responsible> <docno></docno> <approved></approved> <checked></checked> <date></date> <rev></rev> <file>diameter_transport.xml</file> </header> <module>diameter_transport</module> <modulesummary>Diameter transport interface.</modulesummary> <description> <p> A module specified as a <c>transport_module</c> to <seealso marker="diameter#add_transport">diameter:add_transport/2</seealso> must implement the interface documented here. The interface consists of a function with which diameter starts a transport process and a message interface with which the transport process communicates with the process that starts it (aka its parent).</p> <marker id="start"/> </description> <!-- ===================================================================== --> <funcs> <func> <name>Mod:start({Type, Ref}, Svc, Opts) -> {ok, Pid} | {ok, Pid, LAddrs} | {error, Reason}</name> <fsummary>Start a transport process.</fsummary> <type> <v>Type = connect | accept</v> <v>Ref = <seealso marker="diameter#transport_ref">diameter:transport_ref()</seealso></v> <v>Svc = #diameter_service{}</v> <v>Opts = term()</v> <v>Pid = pid()</v> <v>LAddrs = [<seealso marker="kernel:inet#type-ip_address">inet:ip_address()</seealso>]</v> <v>Reason = term()</v> </type> <desc> <p> Start a transport process. Called by diameter as a consequence of a call to <seealso marker="diameter#add_transport">diameter:add_transport/2</seealso> in order to establish or accept a transport connection respectively. A transport process maintains a connection with a single remote peer.</p> <p> The first argument indicates whether the transport process in question is being started for a connecting (<c>connect</c>) or listening (<c>accept</c>) transport. In the latter case, transport processes are started as required to accept connections from multiple peers. Ref is in each case the same value that was returned from the call to <seealso marker="diameter#add_transport">diameter:add_transport/2</seealso> that has lead to starting of a transport process.</p> <p> A transport process must implement the message interface documented below. It should retain the pid of its parent, monitor the parent and terminate if it dies. It should not link to the parent. It should exit if its transport connection with its peer is lost.</p> <p> The capabilities in the <c>#diameter_service{}</c> record are as passed to <seealso marker="diameter#start_service">diameter:start_service/2</seealso> and <seealso marker="diameter#add_transport">diameter:add_transport/2</seealso>, values passed to the latter overriding those passed to the former. The start function should use the <c>Host-IP-Address</c> list and/or <c>Opts</c> to select an appropriate list of local IP addresses, and should return this list if different from the <c>#diameter_service{}</c> addresses. The returned list is used to populate <c>Host-IP-Address</c> AVPs in outgoing capabilities exchange messages, the <c>#diameter_service{}</c> addresses being used otherwise.</p> <marker id="MESSAGES"/> </desc> </func> </funcs> <!-- ===================================================================== --> <section> <title>MESSAGES</title> <p> All messages sent over the transport interface are of the form <c>{diameter, term()}</c>.</p> <p> A transport process can expect the following messages from diameter.</p> <taglist> <tag><c>{diameter, {send, Packet}}</c></tag> <item> <p> An outbound Diameter message. <c>Packet</c> can be either binary() (the message to be sent) or a <c>#diameter_packet{}</c> record whose <c>transport_data</c> field contains a value other than undefined and whose <c>bin</c> field contains the binary to send.</p> </item> <tag><c>{diameter, {close, Pid}}</c></tag> <item> <p> A request to close the transport connection. The transport process should terminate after closing the connection. <c>Pid</c> is the pid() of the parent process.</p> </item> <tag><c>{diameter, {tls, Ref, Type, Bool}}</c></tag> <item> <p> Indication of whether or not capabilities exchange has selected inband security using TLS. <c>Ref</c> is a reference() that must be included in the <c>{diameter, {tls, Ref}}</c> reply message to the transport's parent process (see below). <c>Type</c> is either <c>connect</c> or <c>accept</c> depending on whether the process has been started for a connecting or listening transport respectively. <c>Bool</c> is a boolean() indicating whether or not the transport connection should be upgraded to TLS.</p> <p> If TLS is requested (<c>Bool=true</c>) then a connecting process should initiate a TLS handshake with the peer and an accepting process should prepare to accept a handshake. A successful handshake should be followed by a <c>{diameter, {tls, Ref}}</c> message to the parent process. A failed handshake should cause the process to exit.</p> <p> This message is only sent to a transport process over whose <c>Inband-Security-Id</c> configuration has indicated support for TLS.</p> </item> </taglist> <p> A transport process should send the following messages to its parent.</p> <taglist> <tag><c>{diameter, {self(), connected}}</c></tag> <item> <p> Inform the parent that the transport process with <c>Type=accept</c> has established a connection with the peer. Not sent if the transport process has <c>Type=connect</c>.</p> </item> <tag><c>{diameter, {self(), connected, Remote}}</c></tag> <item> <p> Inform the parent that the transport process with <c>Type=connect</c> has established a connection with a peer. Not sent if the transport process has <c>Type=accept</c>. <c>Remote</c> is an arbitrary term that uniquely identifies the remote endpoint to which the transport has connected.</p> </item> <tag><c>{diameter, {recv, Packet}}</c></tag> <item> <p> An inbound Diameter message. <c>Packet</c> can be either binary() (the received message) or a <c>#diameter_packet{}</c> record whose <c>bin</c> field contains the received binary(). Any value (other than <c>undefined</c>) set in the <c>transport_data</c> field will be passed back with a corresponding answer message in the case that the inbound message is a request unless the sender sets another value. How <c>transport_data</c> is used/interpreted is up to the transport module.</p> </item> <tag><c>{diameter, {tls, Ref}}</c></tag> <item> <p> Acknowledgment of a successful TLS handshake. <c>Ref</c> is the reference() received in the <c>{diameter, {tls, Ref, Type, Bool}}</c> message in response to which the reply is sent. A transport must exit if a handshake is not successful.</p> </item> </taglist> </section> <!-- ===================================================================== --> <!-- ===================================================================== --> <section> <title>SEE ALSO</title> <p> <seealso marker="diameter_tcp">diameter_tcp(3)</seealso>, <seealso marker="diameter_sctp">diameter_sctp(3)</seealso></p> </section> </erlref>