snmp_asn1.c File Reference

#include "lwip/apps/snmp_opts.h"
#include "snmp_asn1.h"

Functions
err_t	snmp_ans1_enc_tlv (struct snmp_pbuf_stream *pbuf_stream, struct snmp_asn1_tlv *tlv)
err_t	snmp_asn1_enc_raw (struct snmp_pbuf_stream *pbuf_stream, const u8_t *raw, u16_t raw_len)
err_t	snmp_asn1_enc_u32t (struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, u32_t value)
err_t	snmp_asn1_enc_s32t (struct snmp_pbuf_stream *pbuf_stream, u16_t octets_needed, s32_t value)
err_t	snmp_asn1_enc_oid (struct snmp_pbuf_stream *pbuf_stream, const u32_t *oid, u16_t oid_len)
void	snmp_asn1_enc_length_cnt (u16_t length, u8_t *octets_needed)
void	snmp_asn1_enc_u32t_cnt (u32_t value, u16_t *octets_needed)
void	snmp_asn1_enc_s32t_cnt (s32_t value, u16_t *octets_needed)
void	snmp_asn1_enc_oid_cnt (const u32_t *oid, u16_t oid_len, u16_t *octets_needed)
err_t	snmp_asn1_dec_tlv (struct snmp_pbuf_stream *pbuf_stream, struct snmp_asn1_tlv *tlv)
err_t	snmp_asn1_dec_u32t (struct snmp_pbuf_stream *pbuf_stream, u16_t len, u32_t *value)
err_t	snmp_asn1_dec_s32t (struct snmp_pbuf_stream *pbuf_stream, u16_t len, s32_t *value)
err_t	snmp_asn1_dec_oid (struct snmp_pbuf_stream *pbuf_stream, u16_t len, u32_t *oid, u8_t *oid_len, u8_t oid_max_len)
err_t	snmp_asn1_dec_raw (struct snmp_pbuf_stream *pbuf_stream, u16_t len, u8_t *buf, u16_t *buf_len, u16_t buf_max_len)

Detailed Description

Abstract Syntax Notation One (ISO 8824, 8825) encoding

Function Documentation

snmp_ans1_enc_tlv()

err_t snmp_ans1_enc_tlv	(	struct snmp_pbuf_stream *	pbuf_stream,
		struct snmp_asn1_tlv *	tlv
	)

Encodes a TLV into a pbuf stream.

Parameters

pbuf_stream	points to a pbuf stream
tlv	TLV to encode

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) encode

snmp_asn1_dec_oid()

err_t snmp_asn1_dec_oid	(	struct snmp_pbuf_stream *	pbuf_stream,
		u16_t	len,
		u32_t *	oid,
		u8_t *	oid_len,
		u8_t	oid_max_len
	)

Decodes object identifier from incoming message into array of u32_t.

Parameters

pbuf_stream	points to a pbuf stream
len	length of the coded object identifier
oid	return decoded object identifier
oid_len	return decoded object identifier length
oid_max_len	size of oid buffer

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) decode

snmp_asn1_dec_raw()

err_t snmp_asn1_dec_raw	(	struct snmp_pbuf_stream *	pbuf_stream,
		u16_t	len,
		u8_t *	buf,
		u16_t *	buf_len,
		u16_t	buf_max_len
	)

Decodes (copies) raw data (ip-addresses, octet strings, opaque encoding) from incoming message into array.

Parameters

pbuf_stream	points to a pbuf stream
len	length of the coded raw data (zero is valid, e.g. empty string!)
buf	return raw bytes
buf_len	returns length of the raw return value
buf_max_len	buffer size

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) decode

snmp_asn1_dec_s32t()

err_t snmp_asn1_dec_s32t	(	struct snmp_pbuf_stream *	pbuf_stream,
		u16_t	len,
		s32_t *	value
	)

Decodes integer into s32_t.

Parameters

pbuf_stream	points to a pbuf stream
len	length of the coded integer field
value	return host order integer

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) decode

Note

ASN coded integers are always signed!

snmp_asn1_dec_tlv()

err_t snmp_asn1_dec_tlv	(	struct snmp_pbuf_stream *	pbuf_stream,
		struct snmp_asn1_tlv *	tlv
	)

Decodes a TLV from a pbuf stream.

Parameters

pbuf_stream	points to a pbuf stream
tlv	returns decoded TLV

Returns

ERR_OK if successful, ERR_VAL if we can't decode

snmp_asn1_dec_u32t()

err_t snmp_asn1_dec_u32t	(	struct snmp_pbuf_stream *	pbuf_stream,
		u16_t	len,
		u32_t *	value
	)

Decodes positive integer (counter, gauge, timeticks) into u32_t.

Parameters

pbuf_stream	points to a pbuf stream
len	length of the coded integer field
value	return host order integer

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) decode

Note

ASN coded integers are always signed. E.g. +0xFFFF is coded as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!

snmp_asn1_enc_length_cnt()

void snmp_asn1_enc_length_cnt	(	u16_t	length,
		u8_t *	octets_needed
	)

Returns octet count for length.

Parameters

length	parameter length
octets_needed	points to the return value

snmp_asn1_enc_oid()

err_t snmp_asn1_enc_oid	(	struct snmp_pbuf_stream *	pbuf_stream,
		const u32_t *	oid,
		u16_t	oid_len
	)

Encodes object identifier into a pbuf chained ASN1 msg.

Parameters

pbuf_stream	points to a pbuf stream
oid	points to object identifier array
oid_len	object identifier array length

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) encode

snmp_asn1_enc_oid_cnt()

void snmp_asn1_enc_oid_cnt	(	const u32_t *	oid,
		u16_t	oid_len,
		u16_t *	octets_needed
	)

Returns octet count for an object identifier.

Parameters

oid	points to object identifier array
oid_len	object identifier array length
octets_needed	points to the return value

snmp_asn1_enc_raw()

err_t snmp_asn1_enc_raw	(	struct snmp_pbuf_stream *	pbuf_stream,
		const u8_t *	raw,
		u16_t	raw_len
	)

Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg.

Parameters

pbuf_stream	points to a pbuf stream
raw_len	raw data length
raw	points raw data

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) encode

snmp_asn1_enc_s32t()

err_t snmp_asn1_enc_s32t	(	struct snmp_pbuf_stream *	pbuf_stream,
		u16_t	octets_needed,
		s32_t	value
	)

Encodes s32_t integer into a pbuf chained ASN1 msg.

Parameters

pbuf_stream	points to a pbuf stream
octets_needed	encoding length (from snmp_asn1_enc_s32t_cnt())
value	is the host order s32_t value to be encoded

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) encode

See also

snmp_asn1_enc_s32t_cnt()

snmp_asn1_enc_s32t_cnt()

void snmp_asn1_enc_s32t_cnt	(	s32_t	value,
		u16_t *	octets_needed
	)

Returns octet count for an s32_t.

Parameters

value	value to be encoded
octets_needed	points to the return value

Note

ASN coded integers are always signed.

snmp_asn1_enc_u32t()

err_t snmp_asn1_enc_u32t	(	struct snmp_pbuf_stream *	pbuf_stream,
		u16_t	octets_needed,
		u32_t	value
	)

Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg.

Parameters

pbuf_stream	points to a pbuf stream
octets_needed	encoding length (from snmp_asn1_enc_u32t_cnt())
value	is the host order u32_t value to be encoded

Returns

ERR_OK if successful, ERR_ARG if we can't (or won't) encode

See also

snmp_asn1_enc_u32t_cnt()

snmp_asn1_enc_u32t_cnt()

void snmp_asn1_enc_u32t_cnt	(	u32_t	value,
		u16_t *	octets_needed
	)

Returns octet count for an u32_t.

Parameters

value	value to be encoded
octets_needed	points to the return value

Note

ASN coded integers are always signed. E.g. +0xFFFF is coded as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!