snmp_asn1.h File Reference

Functions
err_t	snmp_asn1_dec_type (struct pbuf *p, u16_t ofs, u8_t *type)
err_t	snmp_asn1_dec_length (struct pbuf *p, u16_t ofs, u8_t *octets_used, u16_t *length)
err_t	snmp_asn1_dec_u32t (struct pbuf *p, u16_t ofs, u16_t len, u32_t *value)
err_t	snmp_asn1_dec_s32t (struct pbuf *p, u16_t ofs, u16_t len, s32_t *value)
err_t	snmp_asn1_dec_oid (struct pbuf *p, u16_t ofs, u16_t len, struct snmp_obj_id *oid)
err_t	snmp_asn1_dec_raw (struct pbuf *p, u16_t ofs, u16_t len, u16_t raw_len, u8_t *raw)
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 (u8_t ident_len, s32_t *ident, u16_t *octets_needed)
err_t	snmp_asn1_enc_type (struct pbuf *p, u16_t ofs, u8_t type)
err_t	snmp_asn1_enc_length (struct pbuf *p, u16_t ofs, u16_t length)
err_t	snmp_asn1_enc_u32t (struct pbuf *p, u16_t ofs, u8_t octets_needed, u32_t value)
err_t	snmp_asn1_enc_s32t (struct pbuf *p, u16_t ofs, u8_t octets_needed, s32_t value)
err_t	snmp_asn1_enc_oid (struct pbuf *p, u16_t ofs, u8_t ident_len, s32_t *ident)
err_t	snmp_asn1_enc_raw (struct pbuf *p, u16_t ofs, u8_t raw_len, u8_t *raw)

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Detailed Description

Abstract Syntax Notation One (ISO 8824, 8825) codec.

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Function Documentation

err_t snmp_asn1_dec_length	(	struct pbuf *	p,
		u16_t	ofs,
		u8_t *	octets_used,
		u16_t *	length
	)

Decodes length field from incoming pbuf chain into host length.

Parameters:

	p	points to a pbuf holding an ASN1 coded length
	ofs	points to the offset within the pbuf chain of the ASN1 coded length
	octets_used	returns number of octets used by the length code
	length	return host order length, upto 64k

Returns:

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

Todo:

: do we need to accept inefficient codings with many leading zero's?

err_t snmp_asn1_dec_oid	(	struct pbuf *	p,
		u16_t	ofs,
		u16_t	len,
		struct snmp_obj_id *	oid
	)

Decodes object identifier from incoming message into array of s32_t.

Parameters:

	p	points to a pbuf holding an ASN1 coded object identifier
	ofs	points to the offset within the pbuf chain of the ASN1 coded object identifier
	len	length of the coded object identifier
	oid	return object identifier struct

Returns:

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

err_t snmp_asn1_dec_raw	(	struct pbuf *	p,
		u16_t	ofs,
		u16_t	len,
		u16_t	raw_len,
		u8_t *	raw
	)

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

Parameters:

	p	points to a pbuf holding an ASN1 coded raw data
	ofs	points to the offset within the pbuf chain of the ASN1 coded raw data
	len	length of the coded raw data (zero is valid, e.g. empty string!)
	raw_len	length of the raw return value
	raw	return raw bytes

Returns:

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

err_t snmp_asn1_dec_s32t	(	struct pbuf *	p,
		u16_t	ofs,
		u16_t	len,
		s32_t *	value
	)

Decodes integer into s32_t.

Parameters:

	p	points to a pbuf holding an ASN1 coded integer
	ofs	points to the offset within the pbuf chain of the ASN1 coded integer
	len	length of the coded integer field
	value	return host order integer

Returns:

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

Note:

ASN coded integers are _always_ signed!

err_t snmp_asn1_dec_type	(	struct pbuf *	p,
		u16_t	ofs,
		u8_t *	type
	)

Retrieves type field from incoming pbuf chain.

Parameters:

	p	points to a pbuf holding an ASN1 coded type field
	ofs	points to the offset within the pbuf chain of the ASN1 coded type field
	type	return ASN1 type

Returns:

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

err_t snmp_asn1_dec_u32t	(	struct pbuf *	p,
		u16_t	ofs,
		u16_t	len,
		u32_t *	value
	)

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

Parameters:

	p	points to a pbuf holding an ASN1 coded integer
	ofs	points to the offset within the pbuf chain of the ASN1 coded integer
	len	length of the coded integer field
	value	return host order integer

Returns:

ERR_OK if successfull, 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!!

err_t snmp_asn1_enc_length	(	struct pbuf *	p,
		u16_t	ofs,
		u16_t	length
	)

Encodes host order length field into a pbuf chained ASN1 msg.

Parameters:

	p	points to output pbuf to encode length into
	ofs	points to the offset within the pbuf chain
	length	is the host order length to be encoded

Returns:

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

void snmp_asn1_enc_length_cnt	(	u16_t	length,
		u8_t *	octets_needed
	)

Returns octet count for length.

Parameters:

	length
	octets_needed	points to the return value

err_t snmp_asn1_enc_oid	(	struct pbuf *	p,
		u16_t	ofs,
		u8_t	ident_len,
		s32_t *	ident
	)

Encodes object identifier into a pbuf chained ASN1 msg.

Parameters:

	p	points to output pbuf to encode oid into
	ofs	points to the offset within the pbuf chain
	ident_len	object identifier array length
	ident	points to object identifier array

Returns:

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

void snmp_asn1_enc_oid_cnt	(	u8_t	ident_len,
		s32_t *	ident,
		u16_t *	octets_needed
	)

Returns octet count for an object identifier.

Parameters:

	ident_len	object identifier array length
	ident	points to object identifier array
	octets_needed	points to the return value

err_t snmp_asn1_enc_raw	(	struct pbuf *	p,
		u16_t	ofs,
		u8_t	raw_len,
		u8_t *	raw
	)

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

Parameters:

	p	points to output pbuf to encode raw data into
	ofs	points to the offset within the pbuf chain
	raw_len	raw data length
	raw	points raw data

Returns:

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

err_t snmp_asn1_enc_s32t	(	struct pbuf *	p,
		u16_t	ofs,
		u8_t	octets_needed,
		s32_t	value
	)

Encodes s32_t integer into a pbuf chained ASN1 msg.

Parameters:

	p	points to output pbuf to encode value into
	ofs	points to the offset within the pbuf chain
	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 successfull, ERR_ARG if we can't (or won't) encode

See also:

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
	octets_needed	points to the return value

Note:

ASN coded integers are _always_ signed.

err_t snmp_asn1_enc_type	(	struct pbuf *	p,
		u16_t	ofs,
		u8_t	type
	)

Encodes ASN type field into a pbuf chained ASN1 msg.

Parameters:

	p	points to output pbuf to encode value into
	ofs	points to the offset within the pbuf chain
	type	input ASN1 type

Returns:

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

err_t snmp_asn1_enc_u32t	(	struct pbuf *	p,
		u16_t	ofs,
		u8_t	octets_needed,
		u32_t	value
	)

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

Parameters:

	p	points to output pbuf to encode value into
	ofs	points to the offset within the pbuf chain
	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 successfull, ERR_ARG if we can't (or won't) encode

See also:

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
	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!!

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