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<erlref>
  <header>
    <copyright>
      <year>2004</year><year>2016</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
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    <title>snmpm_mpd</title>
    <prepared></prepared>
    <responsible></responsible>
    <docno></docno>
    <approved></approved>
    <checked></checked>
    <date></date>
    <rev></rev>
    <file>snmpm_mpd.xml</file>
  </header>
  <module since="">snmpm_mpd</module>
  <modulesummary>Message Processing and Dispatch module for the SNMP manager</modulesummary>
  <description>
    <p>The module <c>snmpm_mpd</c> implements the version independent
      Message Processing and Dispatch functionality in SNMP for the manager. 
      It is supposed to be used from a Network Interface process 
      (<seealso marker="snmp_manager_netif">Definition of Manager Net if</seealso>).
      </p>

    <p>Legacy API function <c>process_msg/7</c> that has got separate
      <c>IpAddr</c> and <c>PortNumber</c> arguments still works as before
      for backwards compatibility reasons.</p>
  </description>

  <funcs>
    <func>
      <name since="">init_mpd(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.
                    <marker id="process_msg"></marker>
</p>
      </desc>
    </func>
    <func>
      <name since="OTP 17.3">process_msg(Msg, Domain, Addr, State, NoteStore, Logger) -> {ok, Vsn, Pdu, PduMS, MsgData} | {discarded, Reason}</name>
      <fsummary>Process a message received from the network</fsummary>
      <type>
        <v>Msg = binary()</v>
        <v>Domain = transportDomainUdpIpv4 | transportDomainUdpIpv6</v>
	<v>Addr = {<seealso marker="kernel:inet#type-ip_address">inet:ip_address(), inet:port_number()</seealso>} </v>
        <v>State = mpd_state()</v>
        <v>NoteStore = pid()</v>
        <v>Logger = function()</v>
        <v>Vsn = 'version-1' | 'version-2' | 'version-3'</v>
        <v>Pdu = #pdu</v>
        <v>PduMs = integer()</v>
        <v>MsgData = term()</v>
      </type>
      <desc>
        <p>Processes an incoming message. Performs authentication and 
          decryption as necessary. The return values should be passed the
          manager server.
          </p>
        <p><c>NoteStore</c> is the <c>pid()</c> of the note-store process.</p>
        <p><c>Logger</c> is the function used for audit trail logging.
          </p>
        <p>In the case when the pdu type is <c>report</c>, <c>MsgData</c> is 
          either <c>ok</c> or <c>{error, ReqId, Reason}</c>.
          </p>
      </desc>
    </func>
    <func>
      <name since="">generate_msg(Vsn, NoteStore, Pdu, MsgData, Logger) -> {ok, Packet} | {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 = term()</v>
        <v>Logger = function()</v>
        <v>Packet = binary()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Generates a possibly encrypted packet to be sent to the network.
          </p>
        <p><c>NoteStore</c> is the <c>pid()</c> of the note-store process.
          </p>
        <p><c>MsgData</c> is the message specific data used in the SNMP 
          message. In SNMPv1 and SNMPv2c, this message data is the community 
          string. In SNMPv3, it is the context information.
          </p>
        <p><c>Logger</c> is the function used for audit trail logging.
          </p>
      </desc>
    </func>
    <func>
      <name since="">generate_response_msg(Vsn, Pdu, MsgData, Logger) -> {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>Pdu = #pdu</v>
        <v>MsgData = term()</v>
        <v>Logger = function()</v>
        <v>Packet = binary()</v>
        <v>Reason = term()</v>
      </type>
      <desc>
        <p>Generates a possibly encrypted response 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 from the 
          <seealso marker="snmpm_mpd#process_msg">process_msg</seealso> 
          function.
          </p>
      </desc>
    </func>
  </funcs>
  
</erlref>

