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This library is stripped down version of NetServices library. HTTP server and client function is NOT supported.

lwip/core/snmp/asn1_dec.c@0:dcf3c92487ca, 2011-07-20 (annotated)

Committer:: idinor
Date:: Wed Jul 20 11:45:39 2011 +0000
Revision:: 0:dcf3c92487ca

Who changed what in which revision?

User	Revision	Line number	New contents of line
idinor	0:dcf3c92487ca	1	/**
idinor	0:dcf3c92487ca	2	* @file
idinor	0:dcf3c92487ca	3	* Abstract Syntax Notation One (ISO 8824, 8825) decoding
idinor	0:dcf3c92487ca	4	*
idinor	0:dcf3c92487ca	5	* @todo not optimised (yet), favor correctness over speed, favor speed over size
idinor	0:dcf3c92487ca	6	*/
idinor	0:dcf3c92487ca	7
idinor	0:dcf3c92487ca	8	/*
idinor	0:dcf3c92487ca	9	* Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
idinor	0:dcf3c92487ca	10	* All rights reserved.
idinor	0:dcf3c92487ca	11	*
idinor	0:dcf3c92487ca	12	* Redistribution and use in source and binary forms, with or without modification,
idinor	0:dcf3c92487ca	13	* are permitted provided that the following conditions are met:
idinor	0:dcf3c92487ca	14	*
idinor	0:dcf3c92487ca	15	* 1. Redistributions of source code must retain the above copyright notice,
idinor	0:dcf3c92487ca	16	* this list of conditions and the following disclaimer.
idinor	0:dcf3c92487ca	17	* 2. Redistributions in binary form must reproduce the above copyright notice,
idinor	0:dcf3c92487ca	18	* this list of conditions and the following disclaimer in the documentation
idinor	0:dcf3c92487ca	19	* and/or other materials provided with the distribution.
idinor	0:dcf3c92487ca	20	* 3. The name of the author may not be used to endorse or promote products
idinor	0:dcf3c92487ca	21	* derived from this software without specific prior written permission.
idinor	0:dcf3c92487ca	22	*
idinor	0:dcf3c92487ca	23	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
idinor	0:dcf3c92487ca	24	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
idinor	0:dcf3c92487ca	25	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
idinor	0:dcf3c92487ca	26	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
idinor	0:dcf3c92487ca	27	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
idinor	0:dcf3c92487ca	28	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
idinor	0:dcf3c92487ca	29	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
idinor	0:dcf3c92487ca	30	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
idinor	0:dcf3c92487ca	31	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
idinor	0:dcf3c92487ca	32	* OF SUCH DAMAGE.
idinor	0:dcf3c92487ca	33	*
idinor	0:dcf3c92487ca	34	* Author: Christiaan Simons <christiaan.simons@axon.tv>
idinor	0:dcf3c92487ca	35	*/
idinor	0:dcf3c92487ca	36
idinor	0:dcf3c92487ca	37	#include "lwip/opt.h"
idinor	0:dcf3c92487ca	38
idinor	0:dcf3c92487ca	39	#if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
idinor	0:dcf3c92487ca	40
idinor	0:dcf3c92487ca	41	#include "lwip/snmp_asn1.h"
idinor	0:dcf3c92487ca	42
idinor	0:dcf3c92487ca	43	/**
idinor	0:dcf3c92487ca	44	* Retrieves type field from incoming pbuf chain.
idinor	0:dcf3c92487ca	45	*
idinor	0:dcf3c92487ca	46	* @param p points to a pbuf holding an ASN1 coded type field
idinor	0:dcf3c92487ca	47	* @param ofs points to the offset within the pbuf chain of the ASN1 coded type field
idinor	0:dcf3c92487ca	48	* @param type return ASN1 type
idinor	0:dcf3c92487ca	49	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
idinor	0:dcf3c92487ca	50	*/
idinor	0:dcf3c92487ca	51	err_t
idinor	0:dcf3c92487ca	52	snmp_asn1_dec_type(struct pbuf p, u16_t ofs, u8_t type)
idinor	0:dcf3c92487ca	53	{
idinor	0:dcf3c92487ca	54	u16_t plen, base;
idinor	0:dcf3c92487ca	55	u8_t *msg_ptr;
idinor	0:dcf3c92487ca	56
idinor	0:dcf3c92487ca	57	plen = 0;
idinor	0:dcf3c92487ca	58	while (p != NULL)
idinor	0:dcf3c92487ca	59	{
idinor	0:dcf3c92487ca	60	base = plen;
idinor	0:dcf3c92487ca	61	plen += p->len;
idinor	0:dcf3c92487ca	62	if (ofs < plen)
idinor	0:dcf3c92487ca	63	{
idinor	0:dcf3c92487ca	64	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	65	msg_ptr += ofs - base;
idinor	0:dcf3c92487ca	66	type = msg_ptr;
idinor	0:dcf3c92487ca	67	return ERR_OK;
idinor	0:dcf3c92487ca	68	}
idinor	0:dcf3c92487ca	69	p = p->next;
idinor	0:dcf3c92487ca	70	}
idinor	0:dcf3c92487ca	71	/* p == NULL, ofs >= plen */
idinor	0:dcf3c92487ca	72	return ERR_ARG;
idinor	0:dcf3c92487ca	73	}
idinor	0:dcf3c92487ca	74
idinor	0:dcf3c92487ca	75	/**
idinor	0:dcf3c92487ca	76	* Decodes length field from incoming pbuf chain into host length.
idinor	0:dcf3c92487ca	77	*
idinor	0:dcf3c92487ca	78	* @param p points to a pbuf holding an ASN1 coded length
idinor	0:dcf3c92487ca	79	* @param ofs points to the offset within the pbuf chain of the ASN1 coded length
idinor	0:dcf3c92487ca	80	* @param octets_used returns number of octets used by the length code
idinor	0:dcf3c92487ca	81	* @param length return host order length, upto 64k
idinor	0:dcf3c92487ca	82	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
idinor	0:dcf3c92487ca	83	*/
idinor	0:dcf3c92487ca	84	err_t
idinor	0:dcf3c92487ca	85	snmp_asn1_dec_length(struct pbuf p, u16_t ofs, u8_t octets_used, u16_t *length)
idinor	0:dcf3c92487ca	86	{
idinor	0:dcf3c92487ca	87	u16_t plen, base;
idinor	0:dcf3c92487ca	88	u8_t *msg_ptr;
idinor	0:dcf3c92487ca	89
idinor	0:dcf3c92487ca	90	plen = 0;
idinor	0:dcf3c92487ca	91	while (p != NULL)
idinor	0:dcf3c92487ca	92	{
idinor	0:dcf3c92487ca	93	base = plen;
idinor	0:dcf3c92487ca	94	plen += p->len;
idinor	0:dcf3c92487ca	95	if (ofs < plen)
idinor	0:dcf3c92487ca	96	{
idinor	0:dcf3c92487ca	97	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	98	msg_ptr += ofs - base;
idinor	0:dcf3c92487ca	99
idinor	0:dcf3c92487ca	100	if (*msg_ptr < 0x80)
idinor	0:dcf3c92487ca	101	{
idinor	0:dcf3c92487ca	102	/* primitive definite length format */
idinor	0:dcf3c92487ca	103	*octets_used = 1;
idinor	0:dcf3c92487ca	104	length = msg_ptr;
idinor	0:dcf3c92487ca	105	return ERR_OK;
idinor	0:dcf3c92487ca	106	}
idinor	0:dcf3c92487ca	107	else if (*msg_ptr == 0x80)
idinor	0:dcf3c92487ca	108	{
idinor	0:dcf3c92487ca	109	/* constructed indefinite length format, termination with two zero octets */
idinor	0:dcf3c92487ca	110	u8_t zeros;
idinor	0:dcf3c92487ca	111	u8_t i;
idinor	0:dcf3c92487ca	112
idinor	0:dcf3c92487ca	113	*length = 0;
idinor	0:dcf3c92487ca	114	zeros = 0;
idinor	0:dcf3c92487ca	115	while (zeros != 2)
idinor	0:dcf3c92487ca	116	{
idinor	0:dcf3c92487ca	117	i = 2;
idinor	0:dcf3c92487ca	118	while (i > 0)
idinor	0:dcf3c92487ca	119	{
idinor	0:dcf3c92487ca	120	i--;
idinor	0:dcf3c92487ca	121	(*length) += 1;
idinor	0:dcf3c92487ca	122	ofs += 1;
idinor	0:dcf3c92487ca	123	if (ofs >= plen)
idinor	0:dcf3c92487ca	124	{
idinor	0:dcf3c92487ca	125	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	126	p = p->next;
idinor	0:dcf3c92487ca	127	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	128	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	129	plen += p->len;
idinor	0:dcf3c92487ca	130	}
idinor	0:dcf3c92487ca	131	else
idinor	0:dcf3c92487ca	132	{
idinor	0:dcf3c92487ca	133	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	134	msg_ptr++;
idinor	0:dcf3c92487ca	135	}
idinor	0:dcf3c92487ca	136	if (*msg_ptr == 0)
idinor	0:dcf3c92487ca	137	{
idinor	0:dcf3c92487ca	138	zeros++;
idinor	0:dcf3c92487ca	139	if (zeros == 2)
idinor	0:dcf3c92487ca	140	{
idinor	0:dcf3c92487ca	141	/* stop while (i > 0) */
idinor	0:dcf3c92487ca	142	i = 0;
idinor	0:dcf3c92487ca	143	}
idinor	0:dcf3c92487ca	144	}
idinor	0:dcf3c92487ca	145	else
idinor	0:dcf3c92487ca	146	{
idinor	0:dcf3c92487ca	147	zeros = 0;
idinor	0:dcf3c92487ca	148	}
idinor	0:dcf3c92487ca	149	}
idinor	0:dcf3c92487ca	150	}
idinor	0:dcf3c92487ca	151	*octets_used = 1;
idinor	0:dcf3c92487ca	152	return ERR_OK;
idinor	0:dcf3c92487ca	153	}
idinor	0:dcf3c92487ca	154	else if (*msg_ptr == 0x81)
idinor	0:dcf3c92487ca	155	{
idinor	0:dcf3c92487ca	156	/* constructed definite length format, one octet */
idinor	0:dcf3c92487ca	157	ofs += 1;
idinor	0:dcf3c92487ca	158	if (ofs >= plen)
idinor	0:dcf3c92487ca	159	{
idinor	0:dcf3c92487ca	160	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	161	p = p->next;
idinor	0:dcf3c92487ca	162	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	163	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	164	}
idinor	0:dcf3c92487ca	165	else
idinor	0:dcf3c92487ca	166	{
idinor	0:dcf3c92487ca	167	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	168	msg_ptr++;
idinor	0:dcf3c92487ca	169	}
idinor	0:dcf3c92487ca	170	length = msg_ptr;
idinor	0:dcf3c92487ca	171	*octets_used = 2;
idinor	0:dcf3c92487ca	172	return ERR_OK;
idinor	0:dcf3c92487ca	173	}
idinor	0:dcf3c92487ca	174	else if (*msg_ptr == 0x82)
idinor	0:dcf3c92487ca	175	{
idinor	0:dcf3c92487ca	176	u8_t i;
idinor	0:dcf3c92487ca	177
idinor	0:dcf3c92487ca	178	/* constructed definite length format, two octets */
idinor	0:dcf3c92487ca	179	i = 2;
idinor	0:dcf3c92487ca	180	while (i > 0)
idinor	0:dcf3c92487ca	181	{
idinor	0:dcf3c92487ca	182	i--;
idinor	0:dcf3c92487ca	183	ofs += 1;
idinor	0:dcf3c92487ca	184	if (ofs >= plen)
idinor	0:dcf3c92487ca	185	{
idinor	0:dcf3c92487ca	186	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	187	p = p->next;
idinor	0:dcf3c92487ca	188	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	189	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	190	plen += p->len;
idinor	0:dcf3c92487ca	191	}
idinor	0:dcf3c92487ca	192	else
idinor	0:dcf3c92487ca	193	{
idinor	0:dcf3c92487ca	194	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	195	msg_ptr++;
idinor	0:dcf3c92487ca	196	}
idinor	0:dcf3c92487ca	197	if (i == 0)
idinor	0:dcf3c92487ca	198	{
idinor	0:dcf3c92487ca	199	/* least significant length octet */
idinor	0:dcf3c92487ca	200	length \|= msg_ptr;
idinor	0:dcf3c92487ca	201	}
idinor	0:dcf3c92487ca	202	else
idinor	0:dcf3c92487ca	203	{
idinor	0:dcf3c92487ca	204	/* most significant length octet */
idinor	0:dcf3c92487ca	205	length = (msg_ptr) << 8;
idinor	0:dcf3c92487ca	206	}
idinor	0:dcf3c92487ca	207	}
idinor	0:dcf3c92487ca	208	*octets_used = 3;
idinor	0:dcf3c92487ca	209	return ERR_OK;
idinor	0:dcf3c92487ca	210	}
idinor	0:dcf3c92487ca	211	else
idinor	0:dcf3c92487ca	212	{
idinor	0:dcf3c92487ca	213	/* constructed definite length format 3..127 octets, this is too big (>64k) */
idinor	0:dcf3c92487ca	214	/** @todo: do we need to accept inefficient codings with many leading zero's? */
idinor	0:dcf3c92487ca	215	octets_used = 1 + ((msg_ptr) & 0x7f);
idinor	0:dcf3c92487ca	216	return ERR_ARG;
idinor	0:dcf3c92487ca	217	}
idinor	0:dcf3c92487ca	218	}
idinor	0:dcf3c92487ca	219	p = p->next;
idinor	0:dcf3c92487ca	220	}
idinor	0:dcf3c92487ca	221
idinor	0:dcf3c92487ca	222	/* p == NULL, ofs >= plen */
idinor	0:dcf3c92487ca	223	return ERR_ARG;
idinor	0:dcf3c92487ca	224	}
idinor	0:dcf3c92487ca	225
idinor	0:dcf3c92487ca	226	/**
idinor	0:dcf3c92487ca	227	* Decodes positive integer (counter, gauge, timeticks) into u32_t.
idinor	0:dcf3c92487ca	228	*
idinor	0:dcf3c92487ca	229	* @param p points to a pbuf holding an ASN1 coded integer
idinor	0:dcf3c92487ca	230	* @param ofs points to the offset within the pbuf chain of the ASN1 coded integer
idinor	0:dcf3c92487ca	231	* @param len length of the coded integer field
idinor	0:dcf3c92487ca	232	* @param value return host order integer
idinor	0:dcf3c92487ca	233	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
idinor	0:dcf3c92487ca	234	*
idinor	0:dcf3c92487ca	235	* @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
idinor	0:dcf3c92487ca	236	* as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
idinor	0:dcf3c92487ca	237	* of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
idinor	0:dcf3c92487ca	238	*/
idinor	0:dcf3c92487ca	239	err_t
idinor	0:dcf3c92487ca	240	snmp_asn1_dec_u32t(struct pbuf p, u16_t ofs, u16_t len, u32_t value)
idinor	0:dcf3c92487ca	241	{
idinor	0:dcf3c92487ca	242	u16_t plen, base;
idinor	0:dcf3c92487ca	243	u8_t *msg_ptr;
idinor	0:dcf3c92487ca	244
idinor	0:dcf3c92487ca	245	plen = 0;
idinor	0:dcf3c92487ca	246	while (p != NULL)
idinor	0:dcf3c92487ca	247	{
idinor	0:dcf3c92487ca	248	base = plen;
idinor	0:dcf3c92487ca	249	plen += p->len;
idinor	0:dcf3c92487ca	250	if (ofs < plen)
idinor	0:dcf3c92487ca	251	{
idinor	0:dcf3c92487ca	252	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	253	msg_ptr += ofs - base;
idinor	0:dcf3c92487ca	254	if ((len > 0) && (len < 6))
idinor	0:dcf3c92487ca	255	{
idinor	0:dcf3c92487ca	256	/* start from zero */
idinor	0:dcf3c92487ca	257	*value = 0;
idinor	0:dcf3c92487ca	258	if (*msg_ptr & 0x80)
idinor	0:dcf3c92487ca	259	{
idinor	0:dcf3c92487ca	260	/* negative, expecting zero sign bit! */
idinor	0:dcf3c92487ca	261	return ERR_ARG;
idinor	0:dcf3c92487ca	262	}
idinor	0:dcf3c92487ca	263	else
idinor	0:dcf3c92487ca	264	{
idinor	0:dcf3c92487ca	265	/* positive */
idinor	0:dcf3c92487ca	266	if ((len > 1) && (*msg_ptr == 0))
idinor	0:dcf3c92487ca	267	{
idinor	0:dcf3c92487ca	268	/* skip leading "sign byte" octet 0x00 */
idinor	0:dcf3c92487ca	269	len--;
idinor	0:dcf3c92487ca	270	ofs += 1;
idinor	0:dcf3c92487ca	271	if (ofs >= plen)
idinor	0:dcf3c92487ca	272	{
idinor	0:dcf3c92487ca	273	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	274	p = p->next;
idinor	0:dcf3c92487ca	275	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	276	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	277	plen += p->len;
idinor	0:dcf3c92487ca	278	}
idinor	0:dcf3c92487ca	279	else
idinor	0:dcf3c92487ca	280	{
idinor	0:dcf3c92487ca	281	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	282	msg_ptr++;
idinor	0:dcf3c92487ca	283	}
idinor	0:dcf3c92487ca	284	}
idinor	0:dcf3c92487ca	285	}
idinor	0:dcf3c92487ca	286	/* OR octets with value */
idinor	0:dcf3c92487ca	287	while (len > 1)
idinor	0:dcf3c92487ca	288	{
idinor	0:dcf3c92487ca	289	len--;
idinor	0:dcf3c92487ca	290	value \|= msg_ptr;
idinor	0:dcf3c92487ca	291	*value <<= 8;
idinor	0:dcf3c92487ca	292	ofs += 1;
idinor	0:dcf3c92487ca	293	if (ofs >= plen)
idinor	0:dcf3c92487ca	294	{
idinor	0:dcf3c92487ca	295	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	296	p = p->next;
idinor	0:dcf3c92487ca	297	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	298	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	299	plen += p->len;
idinor	0:dcf3c92487ca	300	}
idinor	0:dcf3c92487ca	301	else
idinor	0:dcf3c92487ca	302	{
idinor	0:dcf3c92487ca	303	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	304	msg_ptr++;
idinor	0:dcf3c92487ca	305	}
idinor	0:dcf3c92487ca	306	}
idinor	0:dcf3c92487ca	307	value \|= msg_ptr;
idinor	0:dcf3c92487ca	308	return ERR_OK;
idinor	0:dcf3c92487ca	309	}
idinor	0:dcf3c92487ca	310	else
idinor	0:dcf3c92487ca	311	{
idinor	0:dcf3c92487ca	312	return ERR_ARG;
idinor	0:dcf3c92487ca	313	}
idinor	0:dcf3c92487ca	314	}
idinor	0:dcf3c92487ca	315	p = p->next;
idinor	0:dcf3c92487ca	316	}
idinor	0:dcf3c92487ca	317	/* p == NULL, ofs >= plen */
idinor	0:dcf3c92487ca	318	return ERR_ARG;
idinor	0:dcf3c92487ca	319	}
idinor	0:dcf3c92487ca	320
idinor	0:dcf3c92487ca	321	/**
idinor	0:dcf3c92487ca	322	* Decodes integer into s32_t.
idinor	0:dcf3c92487ca	323	*
idinor	0:dcf3c92487ca	324	* @param p points to a pbuf holding an ASN1 coded integer
idinor	0:dcf3c92487ca	325	* @param ofs points to the offset within the pbuf chain of the ASN1 coded integer
idinor	0:dcf3c92487ca	326	* @param len length of the coded integer field
idinor	0:dcf3c92487ca	327	* @param value return host order integer
idinor	0:dcf3c92487ca	328	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
idinor	0:dcf3c92487ca	329	*
idinor	0:dcf3c92487ca	330	* @note ASN coded integers are _always_ signed!
idinor	0:dcf3c92487ca	331	*/
idinor	0:dcf3c92487ca	332	err_t
idinor	0:dcf3c92487ca	333	snmp_asn1_dec_s32t(struct pbuf p, u16_t ofs, u16_t len, s32_t value)
idinor	0:dcf3c92487ca	334	{
idinor	0:dcf3c92487ca	335	u16_t plen, base;
idinor	0:dcf3c92487ca	336	u8_t *msg_ptr;
idinor	0:dcf3c92487ca	337	#if BYTE_ORDER == LITTLE_ENDIAN
idinor	0:dcf3c92487ca	338	u8_t lsb_ptr = (u8_t)value;
idinor	0:dcf3c92487ca	339	#endif
idinor	0:dcf3c92487ca	340	#if BYTE_ORDER == BIG_ENDIAN
idinor	0:dcf3c92487ca	341	u8_t lsb_ptr = (u8_t)value + sizeof(s32_t) - 1;
idinor	0:dcf3c92487ca	342	#endif
idinor	0:dcf3c92487ca	343	u8_t sign;
idinor	0:dcf3c92487ca	344
idinor	0:dcf3c92487ca	345	plen = 0;
idinor	0:dcf3c92487ca	346	while (p != NULL)
idinor	0:dcf3c92487ca	347	{
idinor	0:dcf3c92487ca	348	base = plen;
idinor	0:dcf3c92487ca	349	plen += p->len;
idinor	0:dcf3c92487ca	350	if (ofs < plen)
idinor	0:dcf3c92487ca	351	{
idinor	0:dcf3c92487ca	352	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	353	msg_ptr += ofs - base;
idinor	0:dcf3c92487ca	354	if ((len > 0) && (len < 5))
idinor	0:dcf3c92487ca	355	{
idinor	0:dcf3c92487ca	356	if (*msg_ptr & 0x80)
idinor	0:dcf3c92487ca	357	{
idinor	0:dcf3c92487ca	358	/* negative, start from -1 */
idinor	0:dcf3c92487ca	359	*value = -1;
idinor	0:dcf3c92487ca	360	sign = 1;
idinor	0:dcf3c92487ca	361	}
idinor	0:dcf3c92487ca	362	else
idinor	0:dcf3c92487ca	363	{
idinor	0:dcf3c92487ca	364	/* positive, start from 0 */
idinor	0:dcf3c92487ca	365	*value = 0;
idinor	0:dcf3c92487ca	366	sign = 0;
idinor	0:dcf3c92487ca	367	}
idinor	0:dcf3c92487ca	368	/* OR/AND octets with value */
idinor	0:dcf3c92487ca	369	while (len > 1)
idinor	0:dcf3c92487ca	370	{
idinor	0:dcf3c92487ca	371	len--;
idinor	0:dcf3c92487ca	372	if (sign)
idinor	0:dcf3c92487ca	373	{
idinor	0:dcf3c92487ca	374	lsb_ptr &= msg_ptr;
idinor	0:dcf3c92487ca	375	*value <<= 8;
idinor	0:dcf3c92487ca	376	*lsb_ptr \|= 255;
idinor	0:dcf3c92487ca	377	}
idinor	0:dcf3c92487ca	378	else
idinor	0:dcf3c92487ca	379	{
idinor	0:dcf3c92487ca	380	lsb_ptr \|= msg_ptr;
idinor	0:dcf3c92487ca	381	*value <<= 8;
idinor	0:dcf3c92487ca	382	}
idinor	0:dcf3c92487ca	383	ofs += 1;
idinor	0:dcf3c92487ca	384	if (ofs >= plen)
idinor	0:dcf3c92487ca	385	{
idinor	0:dcf3c92487ca	386	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	387	p = p->next;
idinor	0:dcf3c92487ca	388	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	389	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	390	plen += p->len;
idinor	0:dcf3c92487ca	391	}
idinor	0:dcf3c92487ca	392	else
idinor	0:dcf3c92487ca	393	{
idinor	0:dcf3c92487ca	394	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	395	msg_ptr++;
idinor	0:dcf3c92487ca	396	}
idinor	0:dcf3c92487ca	397	}
idinor	0:dcf3c92487ca	398	if (sign)
idinor	0:dcf3c92487ca	399	{
idinor	0:dcf3c92487ca	400	lsb_ptr &= msg_ptr;
idinor	0:dcf3c92487ca	401	}
idinor	0:dcf3c92487ca	402	else
idinor	0:dcf3c92487ca	403	{
idinor	0:dcf3c92487ca	404	lsb_ptr \|= msg_ptr;
idinor	0:dcf3c92487ca	405	}
idinor	0:dcf3c92487ca	406	return ERR_OK;
idinor	0:dcf3c92487ca	407	}
idinor	0:dcf3c92487ca	408	else
idinor	0:dcf3c92487ca	409	{
idinor	0:dcf3c92487ca	410	return ERR_ARG;
idinor	0:dcf3c92487ca	411	}
idinor	0:dcf3c92487ca	412	}
idinor	0:dcf3c92487ca	413	p = p->next;
idinor	0:dcf3c92487ca	414	}
idinor	0:dcf3c92487ca	415	/* p == NULL, ofs >= plen */
idinor	0:dcf3c92487ca	416	return ERR_ARG;
idinor	0:dcf3c92487ca	417	}
idinor	0:dcf3c92487ca	418
idinor	0:dcf3c92487ca	419	/**
idinor	0:dcf3c92487ca	420	* Decodes object identifier from incoming message into array of s32_t.
idinor	0:dcf3c92487ca	421	*
idinor	0:dcf3c92487ca	422	* @param p points to a pbuf holding an ASN1 coded object identifier
idinor	0:dcf3c92487ca	423	* @param ofs points to the offset within the pbuf chain of the ASN1 coded object identifier
idinor	0:dcf3c92487ca	424	* @param len length of the coded object identifier
idinor	0:dcf3c92487ca	425	* @param oid return object identifier struct
idinor	0:dcf3c92487ca	426	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
idinor	0:dcf3c92487ca	427	*/
idinor	0:dcf3c92487ca	428	err_t
idinor	0:dcf3c92487ca	429	snmp_asn1_dec_oid(struct pbuf p, u16_t ofs, u16_t len, struct snmp_obj_id oid)
idinor	0:dcf3c92487ca	430	{
idinor	0:dcf3c92487ca	431	u16_t plen, base;
idinor	0:dcf3c92487ca	432	u8_t *msg_ptr;
idinor	0:dcf3c92487ca	433	s32_t *oid_ptr;
idinor	0:dcf3c92487ca	434
idinor	0:dcf3c92487ca	435	plen = 0;
idinor	0:dcf3c92487ca	436	while (p != NULL)
idinor	0:dcf3c92487ca	437	{
idinor	0:dcf3c92487ca	438	base = plen;
idinor	0:dcf3c92487ca	439	plen += p->len;
idinor	0:dcf3c92487ca	440	if (ofs < plen)
idinor	0:dcf3c92487ca	441	{
idinor	0:dcf3c92487ca	442	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	443	msg_ptr += ofs - base;
idinor	0:dcf3c92487ca	444
idinor	0:dcf3c92487ca	445	oid->len = 0;
idinor	0:dcf3c92487ca	446	oid_ptr = &oid->id[0];
idinor	0:dcf3c92487ca	447	if (len > 0)
idinor	0:dcf3c92487ca	448	{
idinor	0:dcf3c92487ca	449	/* first compressed octet */
idinor	0:dcf3c92487ca	450	if (*msg_ptr == 0x2B)
idinor	0:dcf3c92487ca	451	{
idinor	0:dcf3c92487ca	452	/* (most) common case 1.3 (iso.org) */
idinor	0:dcf3c92487ca	453	*oid_ptr = 1;
idinor	0:dcf3c92487ca	454	oid_ptr++;
idinor	0:dcf3c92487ca	455	*oid_ptr = 3;
idinor	0:dcf3c92487ca	456	oid_ptr++;
idinor	0:dcf3c92487ca	457	}
idinor	0:dcf3c92487ca	458	else if (*msg_ptr < 40)
idinor	0:dcf3c92487ca	459	{
idinor	0:dcf3c92487ca	460	*oid_ptr = 0;
idinor	0:dcf3c92487ca	461	oid_ptr++;
idinor	0:dcf3c92487ca	462	oid_ptr = msg_ptr;
idinor	0:dcf3c92487ca	463	oid_ptr++;
idinor	0:dcf3c92487ca	464	}
idinor	0:dcf3c92487ca	465	else if (*msg_ptr < 80)
idinor	0:dcf3c92487ca	466	{
idinor	0:dcf3c92487ca	467	*oid_ptr = 1;
idinor	0:dcf3c92487ca	468	oid_ptr++;
idinor	0:dcf3c92487ca	469	oid_ptr = (msg_ptr) - 40;
idinor	0:dcf3c92487ca	470	oid_ptr++;
idinor	0:dcf3c92487ca	471	}
idinor	0:dcf3c92487ca	472	else
idinor	0:dcf3c92487ca	473	{
idinor	0:dcf3c92487ca	474	*oid_ptr = 2;
idinor	0:dcf3c92487ca	475	oid_ptr++;
idinor	0:dcf3c92487ca	476	oid_ptr = (msg_ptr) - 80;
idinor	0:dcf3c92487ca	477	oid_ptr++;
idinor	0:dcf3c92487ca	478	}
idinor	0:dcf3c92487ca	479	oid->len = 2;
idinor	0:dcf3c92487ca	480	}
idinor	0:dcf3c92487ca	481	else
idinor	0:dcf3c92487ca	482	{
idinor	0:dcf3c92487ca	483	/* accepting zero length identifiers e.g. for
idinor	0:dcf3c92487ca	484	getnext operation. uncommon but valid */
idinor	0:dcf3c92487ca	485	return ERR_OK;
idinor	0:dcf3c92487ca	486	}
idinor	0:dcf3c92487ca	487	len--;
idinor	0:dcf3c92487ca	488	if (len > 0)
idinor	0:dcf3c92487ca	489	{
idinor	0:dcf3c92487ca	490	ofs += 1;
idinor	0:dcf3c92487ca	491	if (ofs >= plen)
idinor	0:dcf3c92487ca	492	{
idinor	0:dcf3c92487ca	493	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	494	p = p->next;
idinor	0:dcf3c92487ca	495	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	496	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	497	plen += p->len;
idinor	0:dcf3c92487ca	498	}
idinor	0:dcf3c92487ca	499	else
idinor	0:dcf3c92487ca	500	{
idinor	0:dcf3c92487ca	501	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	502	msg_ptr++;
idinor	0:dcf3c92487ca	503	}
idinor	0:dcf3c92487ca	504	}
idinor	0:dcf3c92487ca	505	while ((len > 0) && (oid->len < LWIP_SNMP_OBJ_ID_LEN))
idinor	0:dcf3c92487ca	506	{
idinor	0:dcf3c92487ca	507	/* sub-identifier uses multiple octets */
idinor	0:dcf3c92487ca	508	if (*msg_ptr & 0x80)
idinor	0:dcf3c92487ca	509	{
idinor	0:dcf3c92487ca	510	s32_t sub_id = 0;
idinor	0:dcf3c92487ca	511
idinor	0:dcf3c92487ca	512	while ((*msg_ptr & 0x80) && (len > 1))
idinor	0:dcf3c92487ca	513	{
idinor	0:dcf3c92487ca	514	len--;
idinor	0:dcf3c92487ca	515	sub_id = (sub_id << 7) + (*msg_ptr & ~0x80);
idinor	0:dcf3c92487ca	516	ofs += 1;
idinor	0:dcf3c92487ca	517	if (ofs >= plen)
idinor	0:dcf3c92487ca	518	{
idinor	0:dcf3c92487ca	519	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	520	p = p->next;
idinor	0:dcf3c92487ca	521	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	522	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	523	plen += p->len;
idinor	0:dcf3c92487ca	524	}
idinor	0:dcf3c92487ca	525	else
idinor	0:dcf3c92487ca	526	{
idinor	0:dcf3c92487ca	527	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	528	msg_ptr++;
idinor	0:dcf3c92487ca	529	}
idinor	0:dcf3c92487ca	530	}
idinor	0:dcf3c92487ca	531	if (!(*msg_ptr & 0x80) && (len > 0))
idinor	0:dcf3c92487ca	532	{
idinor	0:dcf3c92487ca	533	/* last octet sub-identifier */
idinor	0:dcf3c92487ca	534	len--;
idinor	0:dcf3c92487ca	535	sub_id = (sub_id << 7) + *msg_ptr;
idinor	0:dcf3c92487ca	536	*oid_ptr = sub_id;
idinor	0:dcf3c92487ca	537	}
idinor	0:dcf3c92487ca	538	}
idinor	0:dcf3c92487ca	539	else
idinor	0:dcf3c92487ca	540	{
idinor	0:dcf3c92487ca	541	/* !(msg_ptr & 0x80) sub-identifier uses single octet /
idinor	0:dcf3c92487ca	542	len--;
idinor	0:dcf3c92487ca	543	oid_ptr = msg_ptr;
idinor	0:dcf3c92487ca	544	}
idinor	0:dcf3c92487ca	545	if (len > 0)
idinor	0:dcf3c92487ca	546	{
idinor	0:dcf3c92487ca	547	/* remaining oid bytes available ... */
idinor	0:dcf3c92487ca	548	ofs += 1;
idinor	0:dcf3c92487ca	549	if (ofs >= plen)
idinor	0:dcf3c92487ca	550	{
idinor	0:dcf3c92487ca	551	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	552	p = p->next;
idinor	0:dcf3c92487ca	553	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	554	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	555	plen += p->len;
idinor	0:dcf3c92487ca	556	}
idinor	0:dcf3c92487ca	557	else
idinor	0:dcf3c92487ca	558	{
idinor	0:dcf3c92487ca	559	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	560	msg_ptr++;
idinor	0:dcf3c92487ca	561	}
idinor	0:dcf3c92487ca	562	}
idinor	0:dcf3c92487ca	563	oid_ptr++;
idinor	0:dcf3c92487ca	564	oid->len++;
idinor	0:dcf3c92487ca	565	}
idinor	0:dcf3c92487ca	566	if (len == 0)
idinor	0:dcf3c92487ca	567	{
idinor	0:dcf3c92487ca	568	/* len == 0, end of oid */
idinor	0:dcf3c92487ca	569	return ERR_OK;
idinor	0:dcf3c92487ca	570	}
idinor	0:dcf3c92487ca	571	else
idinor	0:dcf3c92487ca	572	{
idinor	0:dcf3c92487ca	573	/* len > 0, oid->len == LWIP_SNMP_OBJ_ID_LEN or malformed encoding */
idinor	0:dcf3c92487ca	574	return ERR_ARG;
idinor	0:dcf3c92487ca	575	}
idinor	0:dcf3c92487ca	576
idinor	0:dcf3c92487ca	577	}
idinor	0:dcf3c92487ca	578	p = p->next;
idinor	0:dcf3c92487ca	579	}
idinor	0:dcf3c92487ca	580	/* p == NULL, ofs >= plen */
idinor	0:dcf3c92487ca	581	return ERR_ARG;
idinor	0:dcf3c92487ca	582	}
idinor	0:dcf3c92487ca	583
idinor	0:dcf3c92487ca	584	/**
idinor	0:dcf3c92487ca	585	* Decodes (copies) raw data (ip-addresses, octet strings, opaque encoding)
idinor	0:dcf3c92487ca	586	* from incoming message into array.
idinor	0:dcf3c92487ca	587	*
idinor	0:dcf3c92487ca	588	* @param p points to a pbuf holding an ASN1 coded raw data
idinor	0:dcf3c92487ca	589	* @param ofs points to the offset within the pbuf chain of the ASN1 coded raw data
idinor	0:dcf3c92487ca	590	* @param len length of the coded raw data (zero is valid, e.g. empty string!)
idinor	0:dcf3c92487ca	591	* @param raw_len length of the raw return value
idinor	0:dcf3c92487ca	592	* @param raw return raw bytes
idinor	0:dcf3c92487ca	593	* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
idinor	0:dcf3c92487ca	594	*/
idinor	0:dcf3c92487ca	595	err_t
idinor	0:dcf3c92487ca	596	snmp_asn1_dec_raw(struct pbuf p, u16_t ofs, u16_t len, u16_t raw_len, u8_t raw)
idinor	0:dcf3c92487ca	597	{
idinor	0:dcf3c92487ca	598	u16_t plen, base;
idinor	0:dcf3c92487ca	599	u8_t *msg_ptr;
idinor	0:dcf3c92487ca	600
idinor	0:dcf3c92487ca	601	if (len > 0)
idinor	0:dcf3c92487ca	602	{
idinor	0:dcf3c92487ca	603	plen = 0;
idinor	0:dcf3c92487ca	604	while (p != NULL)
idinor	0:dcf3c92487ca	605	{
idinor	0:dcf3c92487ca	606	base = plen;
idinor	0:dcf3c92487ca	607	plen += p->len;
idinor	0:dcf3c92487ca	608	if (ofs < plen)
idinor	0:dcf3c92487ca	609	{
idinor	0:dcf3c92487ca	610	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	611	msg_ptr += ofs - base;
idinor	0:dcf3c92487ca	612	if (raw_len >= len)
idinor	0:dcf3c92487ca	613	{
idinor	0:dcf3c92487ca	614	while (len > 1)
idinor	0:dcf3c92487ca	615	{
idinor	0:dcf3c92487ca	616	/* copy len - 1 octets */
idinor	0:dcf3c92487ca	617	len--;
idinor	0:dcf3c92487ca	618	raw = msg_ptr;
idinor	0:dcf3c92487ca	619	raw++;
idinor	0:dcf3c92487ca	620	ofs += 1;
idinor	0:dcf3c92487ca	621	if (ofs >= plen)
idinor	0:dcf3c92487ca	622	{
idinor	0:dcf3c92487ca	623	/* next octet in next pbuf */
idinor	0:dcf3c92487ca	624	p = p->next;
idinor	0:dcf3c92487ca	625	if (p == NULL) { return ERR_ARG; }
idinor	0:dcf3c92487ca	626	msg_ptr = (u8_t*)p->payload;
idinor	0:dcf3c92487ca	627	plen += p->len;
idinor	0:dcf3c92487ca	628	}
idinor	0:dcf3c92487ca	629	else
idinor	0:dcf3c92487ca	630	{
idinor	0:dcf3c92487ca	631	/* next octet in same pbuf */
idinor	0:dcf3c92487ca	632	msg_ptr++;
idinor	0:dcf3c92487ca	633	}
idinor	0:dcf3c92487ca	634	}
idinor	0:dcf3c92487ca	635	/* copy last octet */
idinor	0:dcf3c92487ca	636	raw = msg_ptr;
idinor	0:dcf3c92487ca	637	return ERR_OK;
idinor	0:dcf3c92487ca	638	}
idinor	0:dcf3c92487ca	639	else
idinor	0:dcf3c92487ca	640	{
idinor	0:dcf3c92487ca	641	/* raw_len < len, not enough dst space */
idinor	0:dcf3c92487ca	642	return ERR_ARG;
idinor	0:dcf3c92487ca	643	}
idinor	0:dcf3c92487ca	644	}
idinor	0:dcf3c92487ca	645	p = p->next;
idinor	0:dcf3c92487ca	646	}
idinor	0:dcf3c92487ca	647	/* p == NULL, ofs >= plen */
idinor	0:dcf3c92487ca	648	return ERR_ARG;
idinor	0:dcf3c92487ca	649	}
idinor	0:dcf3c92487ca	650	else
idinor	0:dcf3c92487ca	651	{
idinor	0:dcf3c92487ca	652	/* len == 0, empty string */
idinor	0:dcf3c92487ca	653	return ERR_OK;
idinor	0:dcf3c92487ca	654	}
idinor	0:dcf3c92487ca	655	}
idinor	0:dcf3c92487ca	656
idinor	0:dcf3c92487ca	657	#endif /* LWIP_SNMP */

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Type:	Library
Created:	20 Jul 2011
Imports:	35
Forks:	0
Commits:	1
Dependents:	1
Dependencies:	0
Followers:	1

lwip/core/snmp/asn1_dec.c@0:dcf3c92487ca, 2011-07-20 (annotated)

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