View Source snmp_pdus (snmp v5.16)

Encode and Decode Functions for SNMP PDUs

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.

Summary

Types

message()

The message is version dependent. 'vsn_hdr' is either a community string (v1 and v2) or a 'v3_hdr' record (v3). 'data' is either a PDU (v1 and v2c) or a (possibly encrypted) 'scopedPdu'.

msg_id()

msg_security_model()

pdu()

pdu_type()

scoped_pdu()

trappdu()

usm_security_parameters()

v3_hdr()

version()

Functions

dec_message(Bytes)

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(Bytes)

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(Bytes)

Decodes a list of bytes into an SNMP Pdu.

dec_scoped_pdu(Bytes)

Decodes a list of bytes into an SNMP ScopedPdu.

dec_scoped_pdu_data(Bytes)

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(Bytes)

Decodes a list of bytes into an SNMP UsmSecurityParameters.

enc_message(Message)

Encodes a message record to a list of bytes.

enc_message_only(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(Pdu)

Encodes an SNMP Pdu into a list of bytes.

enc_scoped_pdu(ScopedPdu)

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)

Encodes SNMP UsmSecurityParameters into a list of bytes.

Types

message()

-type message() :: #message{version :: term(), vsn_hdr :: term(), data :: term()}.

The message is version dependent. 'vsn_hdr' is either a community string (v1 and v2) or a 'v3_hdr' record (v3). 'data' is either a PDU (v1 and v2c) or a (possibly encrypted) 'scopedPdu'.

msg_id()

-type msg_id() :: 0..2147483647.

msg_security_model()

-type msg_security_model() :: 0..2147483647.

pdu()

-type pdu() ::
    #pdu{type :: term(),
         request_id :: term(),
         error_status :: term(),
         error_index :: term(),
         varbinds :: term()}.

pdu_type()

-type pdu_type() ::
    'get-request' | 'get-next-request' | 'get-bulk-request' | 'get-response' | 'set-request' |
    'inform-request' | 'snmpv2-trap' | report.

scoped_pdu()

-type scoped_pdu() :: #scopedPdu{contextEngineID :: term(), contextName :: term(), data :: term()}.

trappdu()

-type trappdu() ::
    #trappdu{enterprise :: term(),
             agent_addr :: term(),
             generic_trap :: term(),
             specific_trap :: term(),
             time_stamp :: term(),
             varbinds :: term()}.

usm_security_parameters()

-type usm_security_parameters() ::
    #usmSecurityParameters{msgAuthoritativeEngineID :: term(),
                           msgAuthoritativeEngineBoots :: term(),
                           msgAuthoritativeEngineTime :: term(),
                           msgUserName :: term(),
                           msgAuthenticationParameters :: term(),
                           msgPrivacyParameters :: term()}.

v3_hdr()

-type v3_hdr() ::
    #v3_hdr{msgID :: term(),
            msgMaxSize :: term(),
            msgFlags :: term(),
            msgSecurityModel :: term(),
            msgSecurityParameters :: term(),
            hdr_size :: term()}.

version()

-type version() :: 'version-1' | 'version-2' | 'version-3'.

Functions

dec_message(Bytes)

-spec dec_message(Bytes) -> Message when Bytes :: [byte()], 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(Bytes)

-spec dec_message_only(Bytes) -> Message when Bytes :: [byte()], 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(Bytes)

-spec dec_pdu(Bytes) -> Pdu when Bytes :: [byte()], Pdu :: trappdu() | pdu().

Decodes a list of bytes into an SNMP Pdu.

dec_scoped_pdu(Bytes)

-spec dec_scoped_pdu(Bytes) -> ScopedPDU when Bytes :: [byte()], ScopedPDU :: scoped_pdu().

Decodes a list of bytes into an SNMP ScopedPdu.

dec_scoped_pdu_data(Bytes)

-spec dec_scoped_pdu_data(Bytes) -> ScopedPduData
                       when
                           Bytes :: [byte()],
                           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(Bytes)

-spec dec_usm_security_parameters(Bytes) -> UsmSecParams
                               when Bytes :: [byte()], UsmSecParams :: usm_security_parameters().

Decodes a list of bytes into an SNMP UsmSecurityParameters.

enc_message(Message)

-spec enc_message(Message) -> Bytes when Message :: message(), Bytes :: [byte()].

Encodes a message record to a list of bytes.

enc_message_only(Message)

-spec enc_message_only(Message) -> Bytes when Message :: message(), Bytes :: [byte()].

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(Pdu)

-spec enc_pdu(Pdu) -> Bytes when Pdu :: pdu(), Bytes :: [byte()].

Encodes an SNMP Pdu into a list of bytes.

enc_scoped_pdu(ScopedPdu)

-spec enc_scoped_pdu(ScopedPdu) -> Bytes when ScopedPdu :: scoped_pdu(), Bytes :: [byte()].

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)

-spec enc_usm_security_parameters(UsmSecParams) -> Bytes
                               when UsmSecParams :: usm_security_parameters(), Bytes :: [byte()].

Encodes SNMP UsmSecurityParameters into a list of bytes.