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lwip/core/snmp/asn1_enc.c@0:d616ece2d859, 2010-09-18 (annotated)

Committer:: mbed714
Date:: Sat Sep 18 23:05:49 2010 +0000
Revision:: 0:d616ece2d859

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User	Revision	Line number	New contents of line
mbed714	0:d616ece2d859	1	/**
mbed714	0:d616ece2d859	2	* @file
mbed714	0:d616ece2d859	3	* Abstract Syntax Notation One (ISO 8824, 8825) encoding
mbed714	0:d616ece2d859	4	*
mbed714	0:d616ece2d859	5	* @todo not optimised (yet), favor correctness over speed, favor speed over size
mbed714	0:d616ece2d859	6	*/
mbed714	0:d616ece2d859	7
mbed714	0:d616ece2d859	8	/*
mbed714	0:d616ece2d859	9	* Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
mbed714	0:d616ece2d859	10	* All rights reserved.
mbed714	0:d616ece2d859	11	*
mbed714	0:d616ece2d859	12	* Redistribution and use in source and binary forms, with or without modification,
mbed714	0:d616ece2d859	13	* are permitted provided that the following conditions are met:
mbed714	0:d616ece2d859	14	*
mbed714	0:d616ece2d859	15	* 1. Redistributions of source code must retain the above copyright notice,
mbed714	0:d616ece2d859	16	* this list of conditions and the following disclaimer.
mbed714	0:d616ece2d859	17	* 2. Redistributions in binary form must reproduce the above copyright notice,
mbed714	0:d616ece2d859	18	* this list of conditions and the following disclaimer in the documentation
mbed714	0:d616ece2d859	19	* and/or other materials provided with the distribution.
mbed714	0:d616ece2d859	20	* 3. The name of the author may not be used to endorse or promote products
mbed714	0:d616ece2d859	21	* derived from this software without specific prior written permission.
mbed714	0:d616ece2d859	22	*
mbed714	0:d616ece2d859	23	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
mbed714	0:d616ece2d859	24	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
mbed714	0:d616ece2d859	25	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
mbed714	0:d616ece2d859	26	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
mbed714	0:d616ece2d859	27	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
mbed714	0:d616ece2d859	28	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
mbed714	0:d616ece2d859	29	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
mbed714	0:d616ece2d859	30	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
mbed714	0:d616ece2d859	31	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
mbed714	0:d616ece2d859	32	* OF SUCH DAMAGE.
mbed714	0:d616ece2d859	33	*
mbed714	0:d616ece2d859	34	* Author: Christiaan Simons <christiaan.simons@axon.tv>
mbed714	0:d616ece2d859	35	*/
mbed714	0:d616ece2d859	36
mbed714	0:d616ece2d859	37	#include "lwip/opt.h"
mbed714	0:d616ece2d859	38
mbed714	0:d616ece2d859	39	#if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
mbed714	0:d616ece2d859	40
mbed714	0:d616ece2d859	41	#include "lwip/snmp_asn1.h"
mbed714	0:d616ece2d859	42
mbed714	0:d616ece2d859	43	/**
mbed714	0:d616ece2d859	44	* Returns octet count for length.
mbed714	0:d616ece2d859	45	*
mbed714	0:d616ece2d859	46	* @param length
mbed714	0:d616ece2d859	47	* @param octets_needed points to the return value
mbed714	0:d616ece2d859	48	*/
mbed714	0:d616ece2d859	49	void
mbed714	0:d616ece2d859	50	snmp_asn1_enc_length_cnt(u16_t length, u8_t *octets_needed)
mbed714	0:d616ece2d859	51	{
mbed714	0:d616ece2d859	52	if (length < 0x80U)
mbed714	0:d616ece2d859	53	{
mbed714	0:d616ece2d859	54	*octets_needed = 1;
mbed714	0:d616ece2d859	55	}
mbed714	0:d616ece2d859	56	else if (length < 0x100U)
mbed714	0:d616ece2d859	57	{
mbed714	0:d616ece2d859	58	*octets_needed = 2;
mbed714	0:d616ece2d859	59	}
mbed714	0:d616ece2d859	60	else
mbed714	0:d616ece2d859	61	{
mbed714	0:d616ece2d859	62	*octets_needed = 3;
mbed714	0:d616ece2d859	63	}
mbed714	0:d616ece2d859	64	}
mbed714	0:d616ece2d859	65
mbed714	0:d616ece2d859	66	/**
mbed714	0:d616ece2d859	67	* Returns octet count for an u32_t.
mbed714	0:d616ece2d859	68	*
mbed714	0:d616ece2d859	69	* @param value
mbed714	0:d616ece2d859	70	* @param octets_needed points to the return value
mbed714	0:d616ece2d859	71	*
mbed714	0:d616ece2d859	72	* @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
mbed714	0:d616ece2d859	73	* as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
mbed714	0:d616ece2d859	74	* of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
mbed714	0:d616ece2d859	75	*/
mbed714	0:d616ece2d859	76	void
mbed714	0:d616ece2d859	77	snmp_asn1_enc_u32t_cnt(u32_t value, u16_t *octets_needed)
mbed714	0:d616ece2d859	78	{
mbed714	0:d616ece2d859	79	if (value < 0x80UL)
mbed714	0:d616ece2d859	80	{
mbed714	0:d616ece2d859	81	*octets_needed = 1;
mbed714	0:d616ece2d859	82	}
mbed714	0:d616ece2d859	83	else if (value < 0x8000UL)
mbed714	0:d616ece2d859	84	{
mbed714	0:d616ece2d859	85	*octets_needed = 2;
mbed714	0:d616ece2d859	86	}
mbed714	0:d616ece2d859	87	else if (value < 0x800000UL)
mbed714	0:d616ece2d859	88	{
mbed714	0:d616ece2d859	89	*octets_needed = 3;
mbed714	0:d616ece2d859	90	}
mbed714	0:d616ece2d859	91	else if (value < 0x80000000UL)
mbed714	0:d616ece2d859	92	{
mbed714	0:d616ece2d859	93	*octets_needed = 4;
mbed714	0:d616ece2d859	94	}
mbed714	0:d616ece2d859	95	else
mbed714	0:d616ece2d859	96	{
mbed714	0:d616ece2d859	97	*octets_needed = 5;
mbed714	0:d616ece2d859	98	}
mbed714	0:d616ece2d859	99	}
mbed714	0:d616ece2d859	100
mbed714	0:d616ece2d859	101	/**
mbed714	0:d616ece2d859	102	* Returns octet count for an s32_t.
mbed714	0:d616ece2d859	103	*
mbed714	0:d616ece2d859	104	* @param value
mbed714	0:d616ece2d859	105	* @param octets_needed points to the return value
mbed714	0:d616ece2d859	106	*
mbed714	0:d616ece2d859	107	* @note ASN coded integers are _always_ signed.
mbed714	0:d616ece2d859	108	*/
mbed714	0:d616ece2d859	109	void
mbed714	0:d616ece2d859	110	snmp_asn1_enc_s32t_cnt(s32_t value, u16_t *octets_needed)
mbed714	0:d616ece2d859	111	{
mbed714	0:d616ece2d859	112	if (value < 0)
mbed714	0:d616ece2d859	113	{
mbed714	0:d616ece2d859	114	value = ~value;
mbed714	0:d616ece2d859	115	}
mbed714	0:d616ece2d859	116	if (value < 0x80L)
mbed714	0:d616ece2d859	117	{
mbed714	0:d616ece2d859	118	*octets_needed = 1;
mbed714	0:d616ece2d859	119	}
mbed714	0:d616ece2d859	120	else if (value < 0x8000L)
mbed714	0:d616ece2d859	121	{
mbed714	0:d616ece2d859	122	*octets_needed = 2;
mbed714	0:d616ece2d859	123	}
mbed714	0:d616ece2d859	124	else if (value < 0x800000L)
mbed714	0:d616ece2d859	125	{
mbed714	0:d616ece2d859	126	*octets_needed = 3;
mbed714	0:d616ece2d859	127	}
mbed714	0:d616ece2d859	128	else
mbed714	0:d616ece2d859	129	{
mbed714	0:d616ece2d859	130	*octets_needed = 4;
mbed714	0:d616ece2d859	131	}
mbed714	0:d616ece2d859	132	}
mbed714	0:d616ece2d859	133
mbed714	0:d616ece2d859	134	/**
mbed714	0:d616ece2d859	135	* Returns octet count for an object identifier.
mbed714	0:d616ece2d859	136	*
mbed714	0:d616ece2d859	137	* @param ident_len object identifier array length
mbed714	0:d616ece2d859	138	* @param ident points to object identifier array
mbed714	0:d616ece2d859	139	* @param octets_needed points to the return value
mbed714	0:d616ece2d859	140	*/
mbed714	0:d616ece2d859	141	void
mbed714	0:d616ece2d859	142	snmp_asn1_enc_oid_cnt(u8_t ident_len, s32_t ident, u16_t octets_needed)
mbed714	0:d616ece2d859	143	{
mbed714	0:d616ece2d859	144	s32_t sub_id;
mbed714	0:d616ece2d859	145	u8_t cnt;
mbed714	0:d616ece2d859	146
mbed714	0:d616ece2d859	147	cnt = 0;
mbed714	0:d616ece2d859	148	if (ident_len > 1)
mbed714	0:d616ece2d859	149	{
mbed714	0:d616ece2d859	150	/* compressed prefix in one octet */
mbed714	0:d616ece2d859	151	cnt++;
mbed714	0:d616ece2d859	152	ident_len -= 2;
mbed714	0:d616ece2d859	153	ident += 2;
mbed714	0:d616ece2d859	154	}
mbed714	0:d616ece2d859	155	while(ident_len > 0)
mbed714	0:d616ece2d859	156	{
mbed714	0:d616ece2d859	157	ident_len--;
mbed714	0:d616ece2d859	158	sub_id = *ident;
mbed714	0:d616ece2d859	159
mbed714	0:d616ece2d859	160	sub_id >>= 7;
mbed714	0:d616ece2d859	161	cnt++;
mbed714	0:d616ece2d859	162	while(sub_id > 0)
mbed714	0:d616ece2d859	163	{
mbed714	0:d616ece2d859	164	sub_id >>= 7;
mbed714	0:d616ece2d859	165	cnt++;
mbed714	0:d616ece2d859	166	}
mbed714	0:d616ece2d859	167	ident++;
mbed714	0:d616ece2d859	168	}
mbed714	0:d616ece2d859	169	*octets_needed = cnt;
mbed714	0:d616ece2d859	170	}
mbed714	0:d616ece2d859	171
mbed714	0:d616ece2d859	172	/**
mbed714	0:d616ece2d859	173	* Encodes ASN type field into a pbuf chained ASN1 msg.
mbed714	0:d616ece2d859	174	*
mbed714	0:d616ece2d859	175	* @param p points to output pbuf to encode value into
mbed714	0:d616ece2d859	176	* @param ofs points to the offset within the pbuf chain
mbed714	0:d616ece2d859	177	* @param type input ASN1 type
mbed714	0:d616ece2d859	178	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
mbed714	0:d616ece2d859	179	*/
mbed714	0:d616ece2d859	180	err_t
mbed714	0:d616ece2d859	181	snmp_asn1_enc_type(struct pbuf *p, u16_t ofs, u8_t type)
mbed714	0:d616ece2d859	182	{
mbed714	0:d616ece2d859	183	u16_t plen, base;
mbed714	0:d616ece2d859	184	u8_t *msg_ptr;
mbed714	0:d616ece2d859	185
mbed714	0:d616ece2d859	186	plen = 0;
mbed714	0:d616ece2d859	187	while (p != NULL)
mbed714	0:d616ece2d859	188	{
mbed714	0:d616ece2d859	189	base = plen;
mbed714	0:d616ece2d859	190	plen += p->len;
mbed714	0:d616ece2d859	191	if (ofs < plen)
mbed714	0:d616ece2d859	192	{
mbed714	0:d616ece2d859	193	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	194	msg_ptr += ofs - base;
mbed714	0:d616ece2d859	195	*msg_ptr = type;
mbed714	0:d616ece2d859	196	return ERR_OK;
mbed714	0:d616ece2d859	197	}
mbed714	0:d616ece2d859	198	p = p->next;
mbed714	0:d616ece2d859	199	}
mbed714	0:d616ece2d859	200	/* p == NULL, ofs >= plen */
mbed714	0:d616ece2d859	201	return ERR_ARG;
mbed714	0:d616ece2d859	202	}
mbed714	0:d616ece2d859	203
mbed714	0:d616ece2d859	204	/**
mbed714	0:d616ece2d859	205	* Encodes host order length field into a pbuf chained ASN1 msg.
mbed714	0:d616ece2d859	206	*
mbed714	0:d616ece2d859	207	* @param p points to output pbuf to encode length into
mbed714	0:d616ece2d859	208	* @param ofs points to the offset within the pbuf chain
mbed714	0:d616ece2d859	209	* @param length is the host order length to be encoded
mbed714	0:d616ece2d859	210	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
mbed714	0:d616ece2d859	211	*/
mbed714	0:d616ece2d859	212	err_t
mbed714	0:d616ece2d859	213	snmp_asn1_enc_length(struct pbuf *p, u16_t ofs, u16_t length)
mbed714	0:d616ece2d859	214	{
mbed714	0:d616ece2d859	215	u16_t plen, base;
mbed714	0:d616ece2d859	216	u8_t *msg_ptr;
mbed714	0:d616ece2d859	217
mbed714	0:d616ece2d859	218	plen = 0;
mbed714	0:d616ece2d859	219	while (p != NULL)
mbed714	0:d616ece2d859	220	{
mbed714	0:d616ece2d859	221	base = plen;
mbed714	0:d616ece2d859	222	plen += p->len;
mbed714	0:d616ece2d859	223	if (ofs < plen)
mbed714	0:d616ece2d859	224	{
mbed714	0:d616ece2d859	225	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	226	msg_ptr += ofs - base;
mbed714	0:d616ece2d859	227
mbed714	0:d616ece2d859	228	if (length < 0x80)
mbed714	0:d616ece2d859	229	{
mbed714	0:d616ece2d859	230	*msg_ptr = (u8_t)length;
mbed714	0:d616ece2d859	231	return ERR_OK;
mbed714	0:d616ece2d859	232	}
mbed714	0:d616ece2d859	233	else if (length < 0x100)
mbed714	0:d616ece2d859	234	{
mbed714	0:d616ece2d859	235	*msg_ptr = 0x81;
mbed714	0:d616ece2d859	236	ofs += 1;
mbed714	0:d616ece2d859	237	if (ofs >= plen)
mbed714	0:d616ece2d859	238	{
mbed714	0:d616ece2d859	239	/* next octet in next pbuf */
mbed714	0:d616ece2d859	240	p = p->next;
mbed714	0:d616ece2d859	241	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	242	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	243	}
mbed714	0:d616ece2d859	244	else
mbed714	0:d616ece2d859	245	{
mbed714	0:d616ece2d859	246	/* next octet in same pbuf */
mbed714	0:d616ece2d859	247	msg_ptr++;
mbed714	0:d616ece2d859	248	}
mbed714	0:d616ece2d859	249	*msg_ptr = (u8_t)length;
mbed714	0:d616ece2d859	250	return ERR_OK;
mbed714	0:d616ece2d859	251	}
mbed714	0:d616ece2d859	252	else
mbed714	0:d616ece2d859	253	{
mbed714	0:d616ece2d859	254	u8_t i;
mbed714	0:d616ece2d859	255
mbed714	0:d616ece2d859	256	/* length >= 0x100 && length <= 0xFFFF */
mbed714	0:d616ece2d859	257	*msg_ptr = 0x82;
mbed714	0:d616ece2d859	258	i = 2;
mbed714	0:d616ece2d859	259	while (i > 0)
mbed714	0:d616ece2d859	260	{
mbed714	0:d616ece2d859	261	i--;
mbed714	0:d616ece2d859	262	ofs += 1;
mbed714	0:d616ece2d859	263	if (ofs >= plen)
mbed714	0:d616ece2d859	264	{
mbed714	0:d616ece2d859	265	/* next octet in next pbuf */
mbed714	0:d616ece2d859	266	p = p->next;
mbed714	0:d616ece2d859	267	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	268	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	269	plen += p->len;
mbed714	0:d616ece2d859	270	}
mbed714	0:d616ece2d859	271	else
mbed714	0:d616ece2d859	272	{
mbed714	0:d616ece2d859	273	/* next octet in same pbuf */
mbed714	0:d616ece2d859	274	msg_ptr++;
mbed714	0:d616ece2d859	275	}
mbed714	0:d616ece2d859	276	if (i == 0)
mbed714	0:d616ece2d859	277	{
mbed714	0:d616ece2d859	278	/* least significant length octet */
mbed714	0:d616ece2d859	279	*msg_ptr = (u8_t)length;
mbed714	0:d616ece2d859	280	}
mbed714	0:d616ece2d859	281	else
mbed714	0:d616ece2d859	282	{
mbed714	0:d616ece2d859	283	/* most significant length octet */
mbed714	0:d616ece2d859	284	*msg_ptr = (u8_t)(length >> 8);
mbed714	0:d616ece2d859	285	}
mbed714	0:d616ece2d859	286	}
mbed714	0:d616ece2d859	287	return ERR_OK;
mbed714	0:d616ece2d859	288	}
mbed714	0:d616ece2d859	289	}
mbed714	0:d616ece2d859	290	p = p->next;
mbed714	0:d616ece2d859	291	}
mbed714	0:d616ece2d859	292	/* p == NULL, ofs >= plen */
mbed714	0:d616ece2d859	293	return ERR_ARG;
mbed714	0:d616ece2d859	294	}
mbed714	0:d616ece2d859	295
mbed714	0:d616ece2d859	296	/**
mbed714	0:d616ece2d859	297	* Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg.
mbed714	0:d616ece2d859	298	*
mbed714	0:d616ece2d859	299	* @param p points to output pbuf to encode value into
mbed714	0:d616ece2d859	300	* @param ofs points to the offset within the pbuf chain
mbed714	0:d616ece2d859	301	* @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
mbed714	0:d616ece2d859	302	* @param value is the host order u32_t value to be encoded
mbed714	0:d616ece2d859	303	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
mbed714	0:d616ece2d859	304	*
mbed714	0:d616ece2d859	305	* @see snmp_asn1_enc_u32t_cnt()
mbed714	0:d616ece2d859	306	*/
mbed714	0:d616ece2d859	307	err_t
mbed714	0:d616ece2d859	308	snmp_asn1_enc_u32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, u32_t value)
mbed714	0:d616ece2d859	309	{
mbed714	0:d616ece2d859	310	u16_t plen, base;
mbed714	0:d616ece2d859	311	u8_t *msg_ptr;
mbed714	0:d616ece2d859	312
mbed714	0:d616ece2d859	313	plen = 0;
mbed714	0:d616ece2d859	314	while (p != NULL)
mbed714	0:d616ece2d859	315	{
mbed714	0:d616ece2d859	316	base = plen;
mbed714	0:d616ece2d859	317	plen += p->len;
mbed714	0:d616ece2d859	318	if (ofs < plen)
mbed714	0:d616ece2d859	319	{
mbed714	0:d616ece2d859	320	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	321	msg_ptr += ofs - base;
mbed714	0:d616ece2d859	322
mbed714	0:d616ece2d859	323	if (octets_needed == 5)
mbed714	0:d616ece2d859	324	{
mbed714	0:d616ece2d859	325	/* not enough bits in 'value' add leading 0x00 */
mbed714	0:d616ece2d859	326	octets_needed--;
mbed714	0:d616ece2d859	327	*msg_ptr = 0x00;
mbed714	0:d616ece2d859	328	ofs += 1;
mbed714	0:d616ece2d859	329	if (ofs >= plen)
mbed714	0:d616ece2d859	330	{
mbed714	0:d616ece2d859	331	/* next octet in next pbuf */
mbed714	0:d616ece2d859	332	p = p->next;
mbed714	0:d616ece2d859	333	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	334	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	335	plen += p->len;
mbed714	0:d616ece2d859	336	}
mbed714	0:d616ece2d859	337	else
mbed714	0:d616ece2d859	338	{
mbed714	0:d616ece2d859	339	/* next octet in same pbuf */
mbed714	0:d616ece2d859	340	msg_ptr++;
mbed714	0:d616ece2d859	341	}
mbed714	0:d616ece2d859	342	}
mbed714	0:d616ece2d859	343	while (octets_needed > 1)
mbed714	0:d616ece2d859	344	{
mbed714	0:d616ece2d859	345	octets_needed--;
mbed714	0:d616ece2d859	346	*msg_ptr = (u8_t)(value >> (octets_needed << 3));
mbed714	0:d616ece2d859	347	ofs += 1;
mbed714	0:d616ece2d859	348	if (ofs >= plen)
mbed714	0:d616ece2d859	349	{
mbed714	0:d616ece2d859	350	/* next octet in next pbuf */
mbed714	0:d616ece2d859	351	p = p->next;
mbed714	0:d616ece2d859	352	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	353	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	354	plen += p->len;
mbed714	0:d616ece2d859	355	}
mbed714	0:d616ece2d859	356	else
mbed714	0:d616ece2d859	357	{
mbed714	0:d616ece2d859	358	/* next octet in same pbuf */
mbed714	0:d616ece2d859	359	msg_ptr++;
mbed714	0:d616ece2d859	360	}
mbed714	0:d616ece2d859	361	}
mbed714	0:d616ece2d859	362	/* (only) one least significant octet */
mbed714	0:d616ece2d859	363	*msg_ptr = (u8_t)value;
mbed714	0:d616ece2d859	364	return ERR_OK;
mbed714	0:d616ece2d859	365	}
mbed714	0:d616ece2d859	366	p = p->next;
mbed714	0:d616ece2d859	367	}
mbed714	0:d616ece2d859	368	/* p == NULL, ofs >= plen */
mbed714	0:d616ece2d859	369	return ERR_ARG;
mbed714	0:d616ece2d859	370	}
mbed714	0:d616ece2d859	371
mbed714	0:d616ece2d859	372	/**
mbed714	0:d616ece2d859	373	* Encodes s32_t integer into a pbuf chained ASN1 msg.
mbed714	0:d616ece2d859	374	*
mbed714	0:d616ece2d859	375	* @param p points to output pbuf to encode value into
mbed714	0:d616ece2d859	376	* @param ofs points to the offset within the pbuf chain
mbed714	0:d616ece2d859	377	* @param octets_needed encoding length (from snmp_asn1_enc_s32t_cnt())
mbed714	0:d616ece2d859	378	* @param value is the host order s32_t value to be encoded
mbed714	0:d616ece2d859	379	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
mbed714	0:d616ece2d859	380	*
mbed714	0:d616ece2d859	381	* @see snmp_asn1_enc_s32t_cnt()
mbed714	0:d616ece2d859	382	*/
mbed714	0:d616ece2d859	383	err_t
mbed714	0:d616ece2d859	384	snmp_asn1_enc_s32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, s32_t value)
mbed714	0:d616ece2d859	385	{
mbed714	0:d616ece2d859	386	u16_t plen, base;
mbed714	0:d616ece2d859	387	u8_t *msg_ptr;
mbed714	0:d616ece2d859	388
mbed714	0:d616ece2d859	389	plen = 0;
mbed714	0:d616ece2d859	390	while (p != NULL)
mbed714	0:d616ece2d859	391	{
mbed714	0:d616ece2d859	392	base = plen;
mbed714	0:d616ece2d859	393	plen += p->len;
mbed714	0:d616ece2d859	394	if (ofs < plen)
mbed714	0:d616ece2d859	395	{
mbed714	0:d616ece2d859	396	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	397	msg_ptr += ofs - base;
mbed714	0:d616ece2d859	398
mbed714	0:d616ece2d859	399	while (octets_needed > 1)
mbed714	0:d616ece2d859	400	{
mbed714	0:d616ece2d859	401	octets_needed--;
mbed714	0:d616ece2d859	402	*msg_ptr = (u8_t)(value >> (octets_needed << 3));
mbed714	0:d616ece2d859	403	ofs += 1;
mbed714	0:d616ece2d859	404	if (ofs >= plen)
mbed714	0:d616ece2d859	405	{
mbed714	0:d616ece2d859	406	/* next octet in next pbuf */
mbed714	0:d616ece2d859	407	p = p->next;
mbed714	0:d616ece2d859	408	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	409	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	410	plen += p->len;
mbed714	0:d616ece2d859	411	}
mbed714	0:d616ece2d859	412	else
mbed714	0:d616ece2d859	413	{
mbed714	0:d616ece2d859	414	/* next octet in same pbuf */
mbed714	0:d616ece2d859	415	msg_ptr++;
mbed714	0:d616ece2d859	416	}
mbed714	0:d616ece2d859	417	}
mbed714	0:d616ece2d859	418	/* (only) one least significant octet */
mbed714	0:d616ece2d859	419	*msg_ptr = (u8_t)value;
mbed714	0:d616ece2d859	420	return ERR_OK;
mbed714	0:d616ece2d859	421	}
mbed714	0:d616ece2d859	422	p = p->next;
mbed714	0:d616ece2d859	423	}
mbed714	0:d616ece2d859	424	/* p == NULL, ofs >= plen */
mbed714	0:d616ece2d859	425	return ERR_ARG;
mbed714	0:d616ece2d859	426	}
mbed714	0:d616ece2d859	427
mbed714	0:d616ece2d859	428	/**
mbed714	0:d616ece2d859	429	* Encodes object identifier into a pbuf chained ASN1 msg.
mbed714	0:d616ece2d859	430	*
mbed714	0:d616ece2d859	431	* @param p points to output pbuf to encode oid into
mbed714	0:d616ece2d859	432	* @param ofs points to the offset within the pbuf chain
mbed714	0:d616ece2d859	433	* @param ident_len object identifier array length
mbed714	0:d616ece2d859	434	* @param ident points to object identifier array
mbed714	0:d616ece2d859	435	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
mbed714	0:d616ece2d859	436	*/
mbed714	0:d616ece2d859	437	err_t
mbed714	0:d616ece2d859	438	snmp_asn1_enc_oid(struct pbuf p, u16_t ofs, u8_t ident_len, s32_t ident)
mbed714	0:d616ece2d859	439	{
mbed714	0:d616ece2d859	440	u16_t plen, base;
mbed714	0:d616ece2d859	441	u8_t *msg_ptr;
mbed714	0:d616ece2d859	442
mbed714	0:d616ece2d859	443	plen = 0;
mbed714	0:d616ece2d859	444	while (p != NULL)
mbed714	0:d616ece2d859	445	{
mbed714	0:d616ece2d859	446	base = plen;
mbed714	0:d616ece2d859	447	plen += p->len;
mbed714	0:d616ece2d859	448	if (ofs < plen)
mbed714	0:d616ece2d859	449	{
mbed714	0:d616ece2d859	450	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	451	msg_ptr += ofs - base;
mbed714	0:d616ece2d859	452
mbed714	0:d616ece2d859	453	if (ident_len > 1)
mbed714	0:d616ece2d859	454	{
mbed714	0:d616ece2d859	455	if ((ident[0] == 1) && (ident[1] == 3))
mbed714	0:d616ece2d859	456	{
mbed714	0:d616ece2d859	457	/* compressed (most common) prefix .iso.org */
mbed714	0:d616ece2d859	458	*msg_ptr = 0x2b;
mbed714	0:d616ece2d859	459	}
mbed714	0:d616ece2d859	460	else
mbed714	0:d616ece2d859	461	{
mbed714	0:d616ece2d859	462	/* calculate prefix */
mbed714	0:d616ece2d859	463	msg_ptr = (u8_t)((ident[0] 40) + ident[1]);
mbed714	0:d616ece2d859	464	}
mbed714	0:d616ece2d859	465	ofs += 1;
mbed714	0:d616ece2d859	466	if (ofs >= plen)
mbed714	0:d616ece2d859	467	{
mbed714	0:d616ece2d859	468	/* next octet in next pbuf */
mbed714	0:d616ece2d859	469	p = p->next;
mbed714	0:d616ece2d859	470	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	471	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	472	plen += p->len;
mbed714	0:d616ece2d859	473	}
mbed714	0:d616ece2d859	474	else
mbed714	0:d616ece2d859	475	{
mbed714	0:d616ece2d859	476	/* next octet in same pbuf */
mbed714	0:d616ece2d859	477	msg_ptr++;
mbed714	0:d616ece2d859	478	}
mbed714	0:d616ece2d859	479	ident_len -= 2;
mbed714	0:d616ece2d859	480	ident += 2;
mbed714	0:d616ece2d859	481	}
mbed714	0:d616ece2d859	482	else
mbed714	0:d616ece2d859	483	{
mbed714	0:d616ece2d859	484	/* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */
mbed714	0:d616ece2d859	485	/* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */
mbed714	0:d616ece2d859	486	return ERR_ARG;
mbed714	0:d616ece2d859	487	}
mbed714	0:d616ece2d859	488	while (ident_len > 0)
mbed714	0:d616ece2d859	489	{
mbed714	0:d616ece2d859	490	s32_t sub_id;
mbed714	0:d616ece2d859	491	u8_t shift, tail;
mbed714	0:d616ece2d859	492
mbed714	0:d616ece2d859	493	ident_len--;
mbed714	0:d616ece2d859	494	sub_id = *ident;
mbed714	0:d616ece2d859	495	tail = 0;
mbed714	0:d616ece2d859	496	shift = 28;
mbed714	0:d616ece2d859	497	while(shift > 0)
mbed714	0:d616ece2d859	498	{
mbed714	0:d616ece2d859	499	u8_t code;
mbed714	0:d616ece2d859	500
mbed714	0:d616ece2d859	501	code = (u8_t)(sub_id >> shift);
mbed714	0:d616ece2d859	502	if ((code != 0) \|\| (tail != 0))
mbed714	0:d616ece2d859	503	{
mbed714	0:d616ece2d859	504	tail = 1;
mbed714	0:d616ece2d859	505	*msg_ptr = code \| 0x80;
mbed714	0:d616ece2d859	506	ofs += 1;
mbed714	0:d616ece2d859	507	if (ofs >= plen)
mbed714	0:d616ece2d859	508	{
mbed714	0:d616ece2d859	509	/* next octet in next pbuf */
mbed714	0:d616ece2d859	510	p = p->next;
mbed714	0:d616ece2d859	511	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	512	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	513	plen += p->len;
mbed714	0:d616ece2d859	514	}
mbed714	0:d616ece2d859	515	else
mbed714	0:d616ece2d859	516	{
mbed714	0:d616ece2d859	517	/* next octet in same pbuf */
mbed714	0:d616ece2d859	518	msg_ptr++;
mbed714	0:d616ece2d859	519	}
mbed714	0:d616ece2d859	520	}
mbed714	0:d616ece2d859	521	shift -= 7;
mbed714	0:d616ece2d859	522	}
mbed714	0:d616ece2d859	523	*msg_ptr = (u8_t)sub_id & 0x7F;
mbed714	0:d616ece2d859	524	if (ident_len > 0)
mbed714	0:d616ece2d859	525	{
mbed714	0:d616ece2d859	526	ofs += 1;
mbed714	0:d616ece2d859	527	if (ofs >= plen)
mbed714	0:d616ece2d859	528	{
mbed714	0:d616ece2d859	529	/* next octet in next pbuf */
mbed714	0:d616ece2d859	530	p = p->next;
mbed714	0:d616ece2d859	531	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	532	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	533	plen += p->len;
mbed714	0:d616ece2d859	534	}
mbed714	0:d616ece2d859	535	else
mbed714	0:d616ece2d859	536	{
mbed714	0:d616ece2d859	537	/* next octet in same pbuf */
mbed714	0:d616ece2d859	538	msg_ptr++;
mbed714	0:d616ece2d859	539	}
mbed714	0:d616ece2d859	540	}
mbed714	0:d616ece2d859	541	/* proceed to next sub-identifier */
mbed714	0:d616ece2d859	542	ident++;
mbed714	0:d616ece2d859	543	}
mbed714	0:d616ece2d859	544	return ERR_OK;
mbed714	0:d616ece2d859	545	}
mbed714	0:d616ece2d859	546	p = p->next;
mbed714	0:d616ece2d859	547	}
mbed714	0:d616ece2d859	548	/* p == NULL, ofs >= plen */
mbed714	0:d616ece2d859	549	return ERR_ARG;
mbed714	0:d616ece2d859	550	}
mbed714	0:d616ece2d859	551
mbed714	0:d616ece2d859	552	/**
mbed714	0:d616ece2d859	553	* Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg.
mbed714	0:d616ece2d859	554	*
mbed714	0:d616ece2d859	555	* @param p points to output pbuf to encode raw data into
mbed714	0:d616ece2d859	556	* @param ofs points to the offset within the pbuf chain
mbed714	0:d616ece2d859	557	* @param raw_len raw data length
mbed714	0:d616ece2d859	558	* @param raw points raw data
mbed714	0:d616ece2d859	559	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
mbed714	0:d616ece2d859	560	*/
mbed714	0:d616ece2d859	561	err_t
mbed714	0:d616ece2d859	562	snmp_asn1_enc_raw(struct pbuf p, u16_t ofs, u16_t raw_len, u8_t raw)
mbed714	0:d616ece2d859	563	{
mbed714	0:d616ece2d859	564	u16_t plen, base;
mbed714	0:d616ece2d859	565	u8_t *msg_ptr;
mbed714	0:d616ece2d859	566
mbed714	0:d616ece2d859	567	plen = 0;
mbed714	0:d616ece2d859	568	while (p != NULL)
mbed714	0:d616ece2d859	569	{
mbed714	0:d616ece2d859	570	base = plen;
mbed714	0:d616ece2d859	571	plen += p->len;
mbed714	0:d616ece2d859	572	if (ofs < plen)
mbed714	0:d616ece2d859	573	{
mbed714	0:d616ece2d859	574	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	575	msg_ptr += ofs - base;
mbed714	0:d616ece2d859	576
mbed714	0:d616ece2d859	577	while (raw_len > 1)
mbed714	0:d616ece2d859	578	{
mbed714	0:d616ece2d859	579	/* copy raw_len - 1 octets */
mbed714	0:d616ece2d859	580	raw_len--;
mbed714	0:d616ece2d859	581	msg_ptr = raw;
mbed714	0:d616ece2d859	582	raw++;
mbed714	0:d616ece2d859	583	ofs += 1;
mbed714	0:d616ece2d859	584	if (ofs >= plen)
mbed714	0:d616ece2d859	585	{
mbed714	0:d616ece2d859	586	/* next octet in next pbuf */
mbed714	0:d616ece2d859	587	p = p->next;
mbed714	0:d616ece2d859	588	if (p == NULL) { return ERR_ARG; }
mbed714	0:d616ece2d859	589	msg_ptr = (u8_t*)p->payload;
mbed714	0:d616ece2d859	590	plen += p->len;
mbed714	0:d616ece2d859	591	}
mbed714	0:d616ece2d859	592	else
mbed714	0:d616ece2d859	593	{
mbed714	0:d616ece2d859	594	/* next octet in same pbuf */
mbed714	0:d616ece2d859	595	msg_ptr++;
mbed714	0:d616ece2d859	596	}
mbed714	0:d616ece2d859	597	}
mbed714	0:d616ece2d859	598	if (raw_len > 0)
mbed714	0:d616ece2d859	599	{
mbed714	0:d616ece2d859	600	/* copy last or single octet */
mbed714	0:d616ece2d859	601	msg_ptr = raw;
mbed714	0:d616ece2d859	602	}
mbed714	0:d616ece2d859	603	return ERR_OK;
mbed714	0:d616ece2d859	604	}
mbed714	0:d616ece2d859	605	p = p->next;
mbed714	0:d616ece2d859	606	}
mbed714	0:d616ece2d859	607	/* p == NULL, ofs >= plen */
mbed714	0:d616ece2d859	608	return ERR_ARG;
mbed714	0:d616ece2d859	609	}
mbed714	0:d616ece2d859	610
mbed714	0:d616ece2d859	611	#endif /* LWIP_SNMP */

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Type:	Library
Created:	18 Sep 2010
Imports:	1
Forks:	0
Commits:	1
Dependents:	0
Dependencies:	0
Followers:	1

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lwip/core/snmp/asn1_enc.c@0:d616ece2d859, 2010-09-18 (annotated)

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