+++ /dev/null
-/**
- * @file
- * Abstract Syntax Notation One (ISO 8824, 8825) decoding
- *
- * @todo not optimised (yet), favor correctness over speed, favor speed over size
- */
-
-/*
- * Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- * this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- * derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- *
- * Author: Christiaan Simons <christiaan.simons@axon.tv>
- */
-
-#include "lwip/opt.h"
-
-#if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
-
-#include "lwip/snmp_asn1.h"
-
-/**
- * Retrieves type field from incoming pbuf chain.
- *
- * @param p points to a pbuf holding an ASN1 coded type field
- * @param ofs points to the offset within the pbuf chain of the ASN1 coded type field
- * @param type return ASN1 type
- * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
- */
-err_t
-snmp_asn1_dec_type(struct pbuf *p, u16_t ofs, u8_t *type)
-{
- u16_t plen, base;
- u8_t *msg_ptr;
-
- plen = 0;
- while (p != NULL)
- {
- base = plen;
- plen += p->len;
- if (ofs < plen)
- {
- msg_ptr = (u8_t*)p->payload;
- msg_ptr += ofs - base;
- *type = *msg_ptr;
- return ERR_OK;
- }
- p = p->next;
- }
- /* p == NULL, ofs >= plen */
- return ERR_ARG;
-}
-
-/**
- * Decodes length field from incoming pbuf chain into host length.
- *
- * @param p points to a pbuf holding an ASN1 coded length
- * @param ofs points to the offset within the pbuf chain of the ASN1 coded length
- * @param octets_used returns number of octets used by the length code
- * @param length return host order length, upto 64k
- * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
- */
-err_t
-snmp_asn1_dec_length(struct pbuf *p, u16_t ofs, u8_t *octets_used, u16_t *length)
-{
- u16_t plen, base;
- u8_t *msg_ptr;
-
- plen = 0;
- while (p != NULL)
- {
- base = plen;
- plen += p->len;
- if (ofs < plen)
- {
- msg_ptr = (u8_t*)p->payload;
- msg_ptr += ofs - base;
-
- if (*msg_ptr < 0x80)
- {
- /* primitive definite length format */
- *octets_used = 1;
- *length = *msg_ptr;
- return ERR_OK;
- }
- else if (*msg_ptr == 0x80)
- {
- /* constructed indefinite length format, termination with two zero octets */
- u8_t zeros;
- u8_t i;
-
- *length = 0;
- zeros = 0;
- while (zeros != 2)
- {
- i = 2;
- while (i > 0)
- {
- i--;
- (*length) += 1;
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- if (*msg_ptr == 0)
- {
- zeros++;
- if (zeros == 2)
- {
- /* stop while (i > 0) */
- i = 0;
- }
- }
- else
- {
- zeros = 0;
- }
- }
- }
- *octets_used = 1;
- return ERR_OK;
- }
- else if (*msg_ptr == 0x81)
- {
- /* constructed definite length format, one octet */
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- *length = *msg_ptr;
- *octets_used = 2;
- return ERR_OK;
- }
- else if (*msg_ptr == 0x82)
- {
- u8_t i;
-
- /* constructed definite length format, two octets */
- i = 2;
- while (i > 0)
- {
- i--;
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- if (i == 0)
- {
- /* least significant length octet */
- *length |= *msg_ptr;
- }
- else
- {
- /* most significant length octet */
- *length = (*msg_ptr) << 8;
- }
- }
- *octets_used = 3;
- return ERR_OK;
- }
- else
- {
- /* constructed definite length format 3..127 octets, this is too big (>64k) */
- /** @todo: do we need to accept inefficient codings with many leading zero's? */
- *octets_used = 1 + ((*msg_ptr) & 0x7f);
- return ERR_ARG;
- }
- }
- p = p->next;
- }
-
- /* p == NULL, ofs >= plen */
- return ERR_ARG;
-}
-
-/**
- * Decodes positive integer (counter, gauge, timeticks) into u32_t.
- *
- * @param p points to a pbuf holding an ASN1 coded integer
- * @param ofs points to the offset within the pbuf chain of the ASN1 coded integer
- * @param len length of the coded integer field
- * @param value return host order integer
- * @return 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_dec_u32t(struct pbuf *p, u16_t ofs, u16_t len, u32_t *value)
-{
- u16_t plen, base;
- u8_t *msg_ptr;
-
- plen = 0;
- while (p != NULL)
- {
- base = plen;
- plen += p->len;
- if (ofs < plen)
- {
- msg_ptr = (u8_t*)p->payload;
- msg_ptr += ofs - base;
- if ((len > 0) && (len < 6))
- {
- /* start from zero */
- *value = 0;
- if (*msg_ptr & 0x80)
- {
- /* negative, expecting zero sign bit! */
- return ERR_ARG;
- }
- else
- {
- /* positive */
- if ((len > 1) && (*msg_ptr == 0))
- {
- /* skip leading "sign byte" octet 0x00 */
- len--;
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- }
- }
- /* OR octets with value */
- while (len > 1)
- {
- len--;
- *value |= *msg_ptr;
- *value <<= 8;
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- }
- *value |= *msg_ptr;
- return ERR_OK;
- }
- else
- {
- return ERR_ARG;
- }
- }
- p = p->next;
- }
- /* p == NULL, ofs >= plen */
- return ERR_ARG;
-}
-
-/**
- * Decodes integer into s32_t.
- *
- * @param p points to a pbuf holding an ASN1 coded integer
- * @param ofs points to the offset within the pbuf chain of the ASN1 coded integer
- * @param len length of the coded integer field
- * @param value return host order integer
- * @return 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_s32t(struct pbuf *p, u16_t ofs, u16_t len, s32_t *value)
-{
- u16_t plen, base;
- u8_t *msg_ptr;
-#if BYTE_ORDER == LITTLE_ENDIAN
- u8_t *lsb_ptr = (u8_t*)value;
-#endif
-#if BYTE_ORDER == BIG_ENDIAN
- u8_t *lsb_ptr = (u8_t*)value + sizeof(s32_t) - 1;
-#endif
- u8_t sign;
-
- plen = 0;
- while (p != NULL)
- {
- base = plen;
- plen += p->len;
- if (ofs < plen)
- {
- msg_ptr = (u8_t*)p->payload;
- msg_ptr += ofs - base;
- if ((len > 0) && (len < 5))
- {
- if (*msg_ptr & 0x80)
- {
- /* negative, start from -1 */
- *value = -1;
- sign = 1;
- }
- else
- {
- /* positive, start from 0 */
- *value = 0;
- sign = 0;
- }
- /* OR/AND octets with value */
- while (len > 1)
- {
- len--;
- if (sign)
- {
- *lsb_ptr &= *msg_ptr;
- *value <<= 8;
- *lsb_ptr |= 255;
- }
- else
- {
- *lsb_ptr |= *msg_ptr;
- *value <<= 8;
- }
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- }
- if (sign)
- {
- *lsb_ptr &= *msg_ptr;
- }
- else
- {
- *lsb_ptr |= *msg_ptr;
- }
- return ERR_OK;
- }
- else
- {
- return ERR_ARG;
- }
- }
- p = p->next;
- }
- /* p == NULL, ofs >= plen */
- return ERR_ARG;
-}
-
-/**
- * Decodes object identifier from incoming message into array of s32_t.
- *
- * @param p points to a pbuf holding an ASN1 coded object identifier
- * @param ofs points to the offset within the pbuf chain of the ASN1 coded object identifier
- * @param len length of the coded object identifier
- * @param oid return object identifier struct
- * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) decode
- */
-err_t
-snmp_asn1_dec_oid(struct pbuf *p, u16_t ofs, u16_t len, struct snmp_obj_id *oid)
-{
- u16_t plen, base;
- u8_t *msg_ptr;
- s32_t *oid_ptr;
-
- plen = 0;
- while (p != NULL)
- {
- base = plen;
- plen += p->len;
- if (ofs < plen)
- {
- msg_ptr = (u8_t*)p->payload;
- msg_ptr += ofs - base;
-
- oid->len = 0;
- oid_ptr = &oid->id[0];
- if (len > 0)
- {
- /* first compressed octet */
- if (*msg_ptr == 0x2B)
- {
- /* (most) common case 1.3 (iso.org) */
- *oid_ptr = 1;
- oid_ptr++;
- *oid_ptr = 3;
- oid_ptr++;
- }
- else if (*msg_ptr < 40)
- {
- *oid_ptr = 0;
- oid_ptr++;
- *oid_ptr = *msg_ptr;
- oid_ptr++;
- }
- else if (*msg_ptr < 80)
- {
- *oid_ptr = 1;
- oid_ptr++;
- *oid_ptr = (*msg_ptr) - 40;
- oid_ptr++;
- }
- else
- {
- *oid_ptr = 2;
- oid_ptr++;
- *oid_ptr = (*msg_ptr) - 80;
- oid_ptr++;
- }
- oid->len = 2;
- }
- else
- {
- /* accepting zero length identifiers e.g. for
- getnext operation. uncommon but valid */
- return ERR_OK;
- }
- len--;
- if (len > 0)
- {
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- }
- while ((len > 0) && (oid->len < LWIP_SNMP_OBJ_ID_LEN))
- {
- /* sub-identifier uses multiple octets */
- if (*msg_ptr & 0x80)
- {
- s32_t sub_id = 0;
-
- while ((*msg_ptr & 0x80) && (len > 1))
- {
- len--;
- sub_id = (sub_id << 7) + (*msg_ptr & ~0x80);
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- }
- if (!(*msg_ptr & 0x80) && (len > 0))
- {
- /* last octet sub-identifier */
- len--;
- sub_id = (sub_id << 7) + *msg_ptr;
- *oid_ptr = sub_id;
- }
- }
- else
- {
- /* !(*msg_ptr & 0x80) sub-identifier uses single octet */
- len--;
- *oid_ptr = *msg_ptr;
- }
- if (len > 0)
- {
- /* remaining oid bytes available ... */
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- }
- oid_ptr++;
- oid->len++;
- }
- if (len == 0)
- {
- /* len == 0, end of oid */
- return ERR_OK;
- }
- else
- {
- /* len > 0, oid->len == LWIP_SNMP_OBJ_ID_LEN or malformed encoding */
- return ERR_ARG;
- }
-
- }
- p = p->next;
- }
- /* p == NULL, ofs >= plen */
- return ERR_ARG;
-}
-
-/**
- * Decodes (copies) raw data (ip-addresses, octet strings, opaque encoding)
- * from incoming message into array.
- *
- * @param p points to a pbuf holding an ASN1 coded raw data
- * @param ofs points to the offset within the pbuf chain of the ASN1 coded raw data
- * @param len length of the coded raw data (zero is valid, e.g. empty string!)
- * @param raw_len length of the raw return value
- * @param raw return raw bytes
- * @return 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)
-{
- u16_t plen, base;
- u8_t *msg_ptr;
-
- if (len > 0)
- {
- plen = 0;
- while (p != NULL)
- {
- base = plen;
- plen += p->len;
- if (ofs < plen)
- {
- msg_ptr = (u8_t*)p->payload;
- msg_ptr += ofs - base;
- if (raw_len >= len)
- {
- while (len > 1)
- {
- /* copy len - 1 octets */
- len--;
- *raw = *msg_ptr;
- raw++;
- ofs += 1;
- if (ofs >= plen)
- {
- /* next octet in next pbuf */
- p = p->next;
- if (p == NULL) { return ERR_ARG; }
- msg_ptr = (u8_t*)p->payload;
- plen += p->len;
- }
- else
- {
- /* next octet in same pbuf */
- msg_ptr++;
- }
- }
- /* copy last octet */
- *raw = *msg_ptr;
- return ERR_OK;
- }
- else
- {
- /* raw_len < len, not enough dst space */
- return ERR_ARG;
- }
- }
- p = p->next;
- }
- /* p == NULL, ofs >= plen */
- return ERR_ARG;
- }
- else
- {
- /* len == 0, empty string */
- return ERR_OK;
- }
-}
-
-#endif /* LWIP_SNMP */
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