611 lines
14 KiB
C
611 lines
14 KiB
C
/**
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* @file
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* Abstract Syntax Notation One (ISO 8824, 8825) encoding
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*
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* @todo not optimised (yet), favor correctness over speed, favor speed over size
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*/
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/*
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* Copyright (c) 2006 Axon Digital Design B.V., The Netherlands.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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* OF SUCH DAMAGE.
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*
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* Author: Christiaan Simons <christiaan.simons@axon.tv>
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*/
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#include "lwip/opt.h"
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#if LWIP_SNMP /* don't build if not configured for use in lwipopts.h */
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#include "lwip/snmp_asn1.h"
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/**
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* Returns octet count for length.
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*
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* @param length
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* @param octets_needed points to the return value
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*/
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void
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snmp_asn1_enc_length_cnt(u16_t length, u8_t *octets_needed)
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{
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if (length < 0x80U)
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{
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*octets_needed = 1;
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}
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else if (length < 0x100U)
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{
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*octets_needed = 2;
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}
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else
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{
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*octets_needed = 3;
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}
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}
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/**
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* Returns octet count for an u32_t.
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*
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* @param value
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* @param octets_needed points to the return value
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*
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* @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded
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* as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value
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* of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!!
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*/
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void
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snmp_asn1_enc_u32t_cnt(u32_t value, u16_t *octets_needed)
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{
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if (value < 0x80UL)
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{
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*octets_needed = 1;
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}
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else if (value < 0x8000UL)
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{
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*octets_needed = 2;
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}
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else if (value < 0x800000UL)
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{
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*octets_needed = 3;
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}
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else if (value < 0x80000000UL)
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{
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*octets_needed = 4;
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}
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else
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{
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*octets_needed = 5;
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}
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}
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/**
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* Returns octet count for an s32_t.
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*
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* @param value
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* @param octets_needed points to the return value
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*
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* @note ASN coded integers are _always_ signed.
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*/
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void
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snmp_asn1_enc_s32t_cnt(s32_t value, u16_t *octets_needed)
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{
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if (value < 0)
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{
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value = ~value;
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}
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if (value < 0x80L)
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{
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*octets_needed = 1;
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}
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else if (value < 0x8000L)
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{
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*octets_needed = 2;
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}
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else if (value < 0x800000L)
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{
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*octets_needed = 3;
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}
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else
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{
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*octets_needed = 4;
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}
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}
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/**
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* Returns octet count for an object identifier.
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*
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* @param ident_len object identifier array length
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* @param ident points to object identifier array
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* @param octets_needed points to the return value
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*/
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void
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snmp_asn1_enc_oid_cnt(u8_t ident_len, s32_t *ident, u16_t *octets_needed)
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{
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s32_t sub_id;
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u8_t cnt;
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cnt = 0;
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if (ident_len > 1)
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{
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/* compressed prefix in one octet */
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cnt++;
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ident_len -= 2;
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ident += 2;
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}
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while(ident_len > 0)
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{
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ident_len--;
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sub_id = *ident;
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sub_id >>= 7;
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cnt++;
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while(sub_id > 0)
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{
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sub_id >>= 7;
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cnt++;
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}
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ident++;
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}
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*octets_needed = cnt;
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}
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/**
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* Encodes ASN type field into a pbuf chained ASN1 msg.
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*
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* @param p points to output pbuf to encode value into
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* @param ofs points to the offset within the pbuf chain
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* @param type input ASN1 type
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* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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*/
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err_t
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snmp_asn1_enc_type(struct pbuf *p, u16_t ofs, u8_t type)
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{
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u16_t plen, base;
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u8_t *msg_ptr;
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plen = 0;
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while (p != NULL)
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{
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base = plen;
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plen += p->len;
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if (ofs < plen)
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{
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msg_ptr = (u8_t*)p->payload;
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msg_ptr += ofs - base;
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*msg_ptr = type;
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return ERR_OK;
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}
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p = p->next;
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}
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/* p == NULL, ofs >= plen */
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return ERR_ARG;
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}
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/**
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* Encodes host order length field into a pbuf chained ASN1 msg.
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*
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* @param p points to output pbuf to encode length into
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* @param ofs points to the offset within the pbuf chain
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* @param length is the host order length to be encoded
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* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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*/
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err_t
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snmp_asn1_enc_length(struct pbuf *p, u16_t ofs, u16_t length)
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{
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u16_t plen, base;
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u8_t *msg_ptr;
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plen = 0;
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while (p != NULL)
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{
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base = plen;
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plen += p->len;
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if (ofs < plen)
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{
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msg_ptr = (u8_t*)p->payload;
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msg_ptr += ofs - base;
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if (length < 0x80)
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{
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*msg_ptr = (u8_t)length;
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return ERR_OK;
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}
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else if (length < 0x100)
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{
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*msg_ptr = 0x81;
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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*msg_ptr = (u8_t)length;
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return ERR_OK;
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}
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else
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{
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u8_t i;
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/* length >= 0x100 && length <= 0xFFFF */
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*msg_ptr = 0x82;
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i = 2;
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while (i > 0)
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{
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i--;
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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plen += p->len;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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if (i == 0)
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{
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/* least significant length octet */
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*msg_ptr = (u8_t)length;
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}
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else
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{
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/* most significant length octet */
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*msg_ptr = (u8_t)(length >> 8);
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}
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}
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return ERR_OK;
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}
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}
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p = p->next;
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}
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/* p == NULL, ofs >= plen */
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return ERR_ARG;
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}
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/**
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* Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg.
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*
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* @param p points to output pbuf to encode value into
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* @param ofs points to the offset within the pbuf chain
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* @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt())
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* @param value is the host order u32_t value to be encoded
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* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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*
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* @see snmp_asn1_enc_u32t_cnt()
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*/
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err_t
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snmp_asn1_enc_u32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, u32_t value)
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{
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u16_t plen, base;
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u8_t *msg_ptr;
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plen = 0;
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while (p != NULL)
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{
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base = plen;
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plen += p->len;
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if (ofs < plen)
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{
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msg_ptr = (u8_t*)p->payload;
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msg_ptr += ofs - base;
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if (octets_needed == 5)
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{
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/* not enough bits in 'value' add leading 0x00 */
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octets_needed--;
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*msg_ptr = 0x00;
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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plen += p->len;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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}
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while (octets_needed > 1)
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{
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octets_needed--;
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*msg_ptr = (u8_t)(value >> (octets_needed << 3));
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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plen += p->len;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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}
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/* (only) one least significant octet */
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*msg_ptr = (u8_t)value;
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return ERR_OK;
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}
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p = p->next;
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}
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/* p == NULL, ofs >= plen */
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return ERR_ARG;
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}
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/**
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* Encodes s32_t integer into a pbuf chained ASN1 msg.
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*
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* @param p points to output pbuf to encode value into
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* @param ofs points to the offset within the pbuf chain
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* @param octets_needed encoding length (from snmp_asn1_enc_s32t_cnt())
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* @param value is the host order s32_t value to be encoded
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* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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*
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* @see snmp_asn1_enc_s32t_cnt()
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*/
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err_t
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snmp_asn1_enc_s32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, s32_t value)
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{
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u16_t plen, base;
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u8_t *msg_ptr;
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plen = 0;
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while (p != NULL)
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{
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base = plen;
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plen += p->len;
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if (ofs < plen)
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{
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msg_ptr = (u8_t*)p->payload;
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msg_ptr += ofs - base;
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while (octets_needed > 1)
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{
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octets_needed--;
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*msg_ptr = (u8_t)(value >> (octets_needed << 3));
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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plen += p->len;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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}
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/* (only) one least significant octet */
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*msg_ptr = (u8_t)value;
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return ERR_OK;
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}
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p = p->next;
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}
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/* p == NULL, ofs >= plen */
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return ERR_ARG;
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}
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/**
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* Encodes object identifier into a pbuf chained ASN1 msg.
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*
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* @param p points to output pbuf to encode oid into
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* @param ofs points to the offset within the pbuf chain
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* @param ident_len object identifier array length
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* @param ident points to object identifier array
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* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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*/
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err_t
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snmp_asn1_enc_oid(struct pbuf *p, u16_t ofs, u8_t ident_len, s32_t *ident)
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{
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u16_t plen, base;
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u8_t *msg_ptr;
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plen = 0;
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while (p != NULL)
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{
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base = plen;
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plen += p->len;
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if (ofs < plen)
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{
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msg_ptr = (u8_t*)p->payload;
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msg_ptr += ofs - base;
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if (ident_len > 1)
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{
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if ((ident[0] == 1) && (ident[1] == 3))
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{
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/* compressed (most common) prefix .iso.org */
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*msg_ptr = 0x2b;
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}
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else
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{
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/* calculate prefix */
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*msg_ptr = (u8_t)((ident[0] * 40) + ident[1]);
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}
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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plen += p->len;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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ident_len -= 2;
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ident += 2;
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}
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else
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{
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/* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */
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/* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */
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return ERR_ARG;
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}
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while (ident_len > 0)
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{
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s32_t sub_id;
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u8_t shift, tail;
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ident_len--;
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sub_id = *ident;
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tail = 0;
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shift = 28;
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while(shift > 0)
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{
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u8_t code;
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code = (u8_t)(sub_id >> shift);
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if ((code != 0) || (tail != 0))
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{
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tail = 1;
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*msg_ptr = code | 0x80;
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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plen += p->len;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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}
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shift -= 7;
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}
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*msg_ptr = (u8_t)sub_id & 0x7F;
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if (ident_len > 0)
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{
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ofs += 1;
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if (ofs >= plen)
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{
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/* next octet in next pbuf */
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p = p->next;
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if (p == NULL) { return ERR_ARG; }
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msg_ptr = (u8_t*)p->payload;
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plen += p->len;
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}
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else
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{
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/* next octet in same pbuf */
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msg_ptr++;
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}
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}
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/* proceed to next sub-identifier */
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ident++;
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}
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return ERR_OK;
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}
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p = p->next;
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}
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/* p == NULL, ofs >= plen */
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return ERR_ARG;
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}
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/**
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* Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg.
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*
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* @param p points to output pbuf to encode raw data into
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* @param ofs points to the offset within the pbuf chain
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* @param raw_len raw data length
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* @param raw points raw data
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* @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode
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*/
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err_t
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snmp_asn1_enc_raw(struct pbuf *p, u16_t ofs, u16_t raw_len, u8_t *raw)
|
|
{
|
|
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;
|
|
|
|
while (raw_len > 1)
|
|
{
|
|
/* copy raw_len - 1 octets */
|
|
raw_len--;
|
|
*msg_ptr = *raw;
|
|
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++;
|
|
}
|
|
}
|
|
if (raw_len > 0)
|
|
{
|
|
/* copy last or single octet */
|
|
*msg_ptr = *raw;
|
|
}
|
|
return ERR_OK;
|
|
}
|
|
p = p->next;
|
|
}
|
|
/* p == NULL, ofs >= plen */
|
|
return ERR_ARG;
|
|
}
|
|
|
|
#endif /* LWIP_SNMP */
|