<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>2004</year><year>2020</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.
      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.
    
    </legalnotice>

    <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 
      (<seeguide marker="snmp_manager_netif">Definition of Manager Net if</seeguide>).
      </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(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 = {<seetype marker="kernel:inet#ip_address">inet:ip_address(), inet:port_number()</seetype>} </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 
          <seeerl marker="snmpm_mpd#process_msg">process_msg</seeerl> 
          function.
          </p>
      </desc>
    </func>
  </funcs>
  
</erlref>

