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<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
<header>
<copyright>
<year>1999</year><year>2013</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>snmpa_mpd</title>
<prepared></prepared>
<responsible></responsible>
<docno></docno>
<approved></approved>
<checked></checked>
<date></date>
<rev></rev>
<file>snmpa_mpd.xml</file>
</header>
<module>snmpa_mpd</module>
<modulesummary>Message Processing and Dispatch module for the SNMP agent</modulesummary>
<description>
<p>The module <c>snmpa_mpd</c> implements the version independent
Message Processing and Dispatch functionality in SNMP for the agent.
It is supposed to be used from a Network Interface process
(<seealso marker="snmp_agent_netif">Definition of Agent Net if</seealso>).
</p>
<marker id="init"></marker>
</description>
<funcs>
<func>
<name>init(Vsns) -> mpd_state()</name>
<fsummary>Initialize the MPD module</fsummary>
<type>
<v>Vsns = [Vsn]</v>
<v>Vsn = v1 | v2 | v3</v>
</type>
<desc>
<p>This function can be called from the net_if process at start-up.
The options list defines which versions to use.
</p>
<p>It also initializes some SNMP counters.
</p>
<marker id="process_packet"></marker>
</desc>
</func>
<func>
<name>process_packet(Packet, TDomain, TAddress, State, NoteStore, Log) -> {ok, Vsn, Pdu, PduMS, ACMData} | {discarded, Reason} | {discovery, DiscoPacket}</name>
<name>process_packet(Packet, TDomain, TAddress, LocalEngineID, State, NoteStore, Log) -> {ok, Vsn, Pdu, PduMS, ACMData} | {discarded, Reason} | {discovery, DiscoPacket}</name>
<fsummary>Process a packet received from the network</fsummary>
<type>
<v>Packet = binary()</v>
<v>TDomain = snmpUDPDomain</v>
<v>TAddress = {Ip, Udp}</v>
<v>LocalEngineID = string()</v>
<v>Ip = {integer(), integer(), integer(), integer()}</v>
<v>Udp = integer()</v>
<v>State = mpd_state()</v>
<v>NoteStore = pid()</v>
<v>Log = snmp_log()</v>
<v>Vsn = 'version-1' | 'version-2' | 'version-3'</v>
<v>Pdu = #pdu</v>
<v>PduMs = integer()</v>
<v>ACMData = acm_data()</v>
<v>Reason = term()</v>
<v>DiscoPacket = binary()</v>
</type>
<desc>
<p>Processes an incoming packet. Performs authentication and
decryption as necessary. The return values should be passed the
agent.</p>
<note>
<p>Note that the use of the LocalEngineID argument is only intended
for special cases, if the agent is to "emulate" multiple EngineIDs!
By default, the agent uses the value of <c>SnmpEngineID</c>
(see SNMP-FRAMEWORK-MIB). </p>
</note>
<marker id="generate_response_msg"></marker>
</desc>
</func>
<func>
<name>generate_response_msg(Vsn, RePdu, Type, ACMData, Log) -> {ok, Packet} | {discarded, Reason}</name>
<name>generate_response_msg(Vsn, RePdu, Type, ACMData, LocalEngineID, Log) -> {ok, Packet} | {discarded, Reason}</name>
<fsummary>Generate a response packet to be sent to the network</fsummary>
<type>
<v>Vsn = 'version-1' | 'version-2' | 'version-3'</v>
<v>RePdu = #pdu</v>
<v>Type = atom()</v>
<v>ACMData = acm_data()</v>
<v>LocalEngineID = string()</v>
<v>Packet = binary()</v>
</type>
<desc>
<p>Generates a possibly encrypted response packet to be sent to the
network. <c>Type</c> is the <c>#pdu.type</c> of the original
request.</p>
<note>
<p>Note that the use of the LocalEngineID argument is only intended
for special cases, if the agent is to "emulate" multiple EngineIDs!
By default, the agent uses the value of <c>SnmpEngineID</c>
(see SNMP-FRAMEWORK-MIB). </p>
</note>
<marker id="generate_msg"></marker>
</desc>
</func>
<func>
<name>generate_msg(Vsn, NoteStore, Pdu, MsgData, To) -> {ok, PacketsAndAddresses} | {discarded, Reason}</name>
<name>generate_msg(Vsn, NoteStore, Pdu, MsgData, LocalEngineID, To) -> {ok, PacketsAndAddresses} | {discarded, Reason}</name>
<fsummary>Generate a request message to be sent to the network</fsummary>
<type>
<v>Vsn = 'version-1' | 'version-2' | 'version-3'</v>
<v>NoteStore = pid()</v>
<v>Pdu = #pdu</v>
<v>MsgData = msg_data()</v>
<v>LocalEngineID = string()</v>
<v>To = [dest_addrs()]</v>
<v>PacketsAndAddresses = [{TDomain, TAddress, Packet}]</v>
<v>TDomain = snmpUDPDomain</v>
<v>TAddress = {Ip, Udp}</v>
<v>Ip = {integer(), integer(), integer(), integer()}</v>
<v>Udp = integer()</v>
<v>Packet = binary()</v>
</type>
<desc>
<p>Generates a possibly encrypted request packet to be sent to the
network.
</p>
<p><c>MsgData</c> is the message specific data used in
the SNMP message. This value is received in a <c>send_pdu</c>
or <c>send_pdu_req</c> message from the agent. In SNMPv1 and
SNMPv2c, this message data is the community string. In
SNMPv3, it is the context information.
<c>To</c> is a list of the destination addresses and
their corresponding security parameters. This value is
also received from the requests mentioned above.
</p>
<note>
<p>Note that the use of the LocalEngineID argument is only intended
for special cases, if the agent is to "emulate" multiple EngineIDs!
By default, the agent uses the value of <c>SnmpEngineID</c>
(see SNMP-FRAMEWORK-MIB). </p>
</note>
<marker id="discarded_pdu"></marker>
</desc>
</func>
<func>
<name>discarded_pdu(Variable) -> void()</name>
<fsummary>Increment the variable associated with a discarded pdu</fsummary>
<type>
<v>Variable = atom()</v>
</type>
<desc>
<p>Increments the variable associated with a discarded pdu.
This function can be used when the net_if process receives a
<c>discarded_pdu</c> message from the agent.
</p>
</desc>
</func>
</funcs>
</erlref>
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