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Simple Network Management Protocol (SNMP)
Reference Manual
Version 4.25

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# snmp_pdus

### MODULE

snmp_pdus

### MODULE SUMMARY

Encode and Decode Functions for SNMP PDUs

### DESCRIPTION

RFC1157, RFC1905 and/or RFC2272 should be studied carefully before using this module, snmp_pdus.

The module snmp_pdus contains functions for encoding and decoding of SNMP protocol data units (PDUs). In short, this module converts a list of bytes to Erlang record representations and vice versa. The record definitions can be found in the file snmp/include/snmp_types.hrl. If snmpv3 is used, the module that includes snmp_types.hrl must define the constant SNMP_USE_V3 before the header file is included. Example:

    -define(SNMP_USE_V3, true).
    -include_lib("snmp/include/snmp_types.hrl").

Encoding and decoding must be done explicitly when writing your own Net if process.

### EXPORTS

dec_message([byte()]) -> Message

Types:

Message = #message

Decodes a list of bytes into an SNMP Message. Note, if there is a v3 message, the msgSecurityParameters are not decoded. They must be explicitly decoded by a call to a security model specific decoding function, e.g. dec_usm_security_parameters/1. Also note, if the scopedPDU is encrypted, the OCTET STRING encoded encryptedPDU will be present in the data field.

dec_message_only([byte()]) -> Message

Types:

Message = #message

Decodes a list of bytes into an SNMP Message, but does not decode the data part of the Message. That means, data is still a list of bytes, normally an encoded PDU (v1 and V2) or an encoded and possibly encrypted scopedPDU (v3).

dec_pdu([byte()]) -> Pdu

Types:

Pdu = #pdu

Decodes a list of bytes into an SNMP Pdu.

dec_scoped_pdu([byte()]) -> ScopedPdu

Types:

ScopedPdu = #scoped_pdu

Decodes a list of bytes into an SNMP ScopedPdu.

dec_scoped_pdu_data([byte()]) -> ScopedPduData

Types:

ScopedPduData = #scoped_pdu | EncryptedPDU
EncryptedPDU = [byte()]

Decodes a list of bytes into either a scoped pdu record, or - if the scoped pdu was encrypted - to a list of bytes.

dec_usm_security_parameters([byte()]) -> UsmSecParams

Types:

UsmSecParams = #usmSecurityParameters

Decodes a list of bytes into an SNMP UsmSecurityParameters

enc_encrypted_scoped_pdu(EncryptedScopedPdu) -> [byte()]

Types:

EncryptedScopedPdu = [byte()]

Encodes an encrypted SNMP ScopedPdu into an OCTET STRING that can be used as the data field in a message record, that later can be encoded with a call to enc_message_only/1.

This function should be used whenever the ScopedPDU is encrypted.

enc_message(Message) -> [byte()]

Types:

Message = #message

Encodes a message record to a list of bytes.

enc_message_only(Message) -> [byte()]

Types:

Message = #message

Message is a record where the data field is assumed to be encoded (a list of bytes). If there is a v1 or v2 message, the data field is an encoded PDU, and if there is a v3 message, data is an encoded and possibly encrypted scopedPDU.

enc_pdu(Pd) -> [byte()]

Types:

Pdu = #pdu

Encodes an SNMP Pdu into a list of bytes.

enc_scoped_pdu(ScopedPdu) -> [byte()]

Types:

ScopedPdu = #scoped_pdu

Encodes an SNMP ScopedPdu into a list of bytes, which can be encrypted, and after encryption, encoded with a call to enc_encrypted_scoped_pdu/1; or it can be used as the data field in a message record, which then can be encoded with enc_message_only/1.

enc_usm_security_parameters(UsmSecParams) -> [byte()]

Types:

UsmSecParams = #usmSecurityParameters

Encodes SNMP UsmSecurityParameters into a list of bytes.