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Diff: lwip/core/snmp/asn1_enc.c
- Revision:
- 0:ac1725ba162c
diff -r 000000000000 -r ac1725ba162c lwip/core/snmp/asn1_enc.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/lwip/core/snmp/asn1_enc.c Tue Nov 09 20:54:15 2010 +0000 @@ -0,0 +1,611 @@ +/** + * @file + * Abstract Syntax Notation One (ISO 8824, 8825) encoding + * + * @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" + +/** + * Returns octet count for length. + * + * @param length + * @param octets_needed points to the return value + */ +void +snmp_asn1_enc_length_cnt(u16_t length, u8_t *octets_needed) +{ + if (length < 0x80U) + { + *octets_needed = 1; + } + else if (length < 0x100U) + { + *octets_needed = 2; + } + else + { + *octets_needed = 3; + } +} + +/** + * Returns octet count for an u32_t. + * + * @param value + * @param octets_needed points to the return value + * + * @note ASN coded integers are _always_ signed. E.g. +0xFFFF is coded + * as 0x00,0xFF,0xFF. Note the leading sign octet. A positive value + * of 0xFFFFFFFF is preceded with 0x00 and the length is 5 octets!! + */ +void +snmp_asn1_enc_u32t_cnt(u32_t value, u16_t *octets_needed) +{ + if (value < 0x80UL) + { + *octets_needed = 1; + } + else if (value < 0x8000UL) + { + *octets_needed = 2; + } + else if (value < 0x800000UL) + { + *octets_needed = 3; + } + else if (value < 0x80000000UL) + { + *octets_needed = 4; + } + else + { + *octets_needed = 5; + } +} + +/** + * Returns octet count for an s32_t. + * + * @param value + * @param octets_needed points to the return value + * + * @note ASN coded integers are _always_ signed. + */ +void +snmp_asn1_enc_s32t_cnt(s32_t value, u16_t *octets_needed) +{ + if (value < 0) + { + value = ~value; + } + if (value < 0x80L) + { + *octets_needed = 1; + } + else if (value < 0x8000L) + { + *octets_needed = 2; + } + else if (value < 0x800000L) + { + *octets_needed = 3; + } + else + { + *octets_needed = 4; + } +} + +/** + * Returns octet count for an object identifier. + * + * @param ident_len object identifier array length + * @param ident points to object identifier array + * @param octets_needed points to the return value + */ +void +snmp_asn1_enc_oid_cnt(u8_t ident_len, s32_t *ident, u16_t *octets_needed) +{ + s32_t sub_id; + u8_t cnt; + + cnt = 0; + if (ident_len > 1) + { + /* compressed prefix in one octet */ + cnt++; + ident_len -= 2; + ident += 2; + } + while(ident_len > 0) + { + ident_len--; + sub_id = *ident; + + sub_id >>= 7; + cnt++; + while(sub_id > 0) + { + sub_id >>= 7; + cnt++; + } + ident++; + } + *octets_needed = cnt; +} + +/** + * Encodes ASN type field into a pbuf chained ASN1 msg. + * + * @param p points to output pbuf to encode value into + * @param ofs points to the offset within the pbuf chain + * @param type input ASN1 type + * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode + */ +err_t +snmp_asn1_enc_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; + *msg_ptr = type; + return ERR_OK; + } + p = p->next; + } + /* p == NULL, ofs >= plen */ + return ERR_ARG; +} + +/** + * Encodes host order length field into a pbuf chained ASN1 msg. + * + * @param p points to output pbuf to encode length into + * @param ofs points to the offset within the pbuf chain + * @param length is the host order length to be encoded + * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode + */ +err_t +snmp_asn1_enc_length(struct pbuf *p, u16_t ofs, 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 (length < 0x80) + { + *msg_ptr = (u8_t)length; + return ERR_OK; + } + else if (length < 0x100) + { + *msg_ptr = 0x81; + 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++; + } + *msg_ptr = (u8_t)length; + return ERR_OK; + } + else + { + u8_t i; + + /* length >= 0x100 && length <= 0xFFFF */ + *msg_ptr = 0x82; + 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 */ + *msg_ptr = (u8_t)length; + } + else + { + /* most significant length octet */ + *msg_ptr = (u8_t)(length >> 8); + } + } + return ERR_OK; + } + } + p = p->next; + } + /* p == NULL, ofs >= plen */ + return ERR_ARG; +} + +/** + * Encodes u32_t (counter, gauge, timeticks) into a pbuf chained ASN1 msg. + * + * @param p points to output pbuf to encode value into + * @param ofs points to the offset within the pbuf chain + * @param octets_needed encoding length (from snmp_asn1_enc_u32t_cnt()) + * @param value is the host order u32_t value to be encoded + * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode + * + * @see snmp_asn1_enc_u32t_cnt() + */ +err_t +snmp_asn1_enc_u32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, 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 (octets_needed == 5) + { + /* not enough bits in 'value' add leading 0x00 */ + octets_needed--; + *msg_ptr = 0x00; + 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 (octets_needed > 1) + { + octets_needed--; + *msg_ptr = (u8_t)(value >> (octets_needed << 3)); + 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++; + } + } + /* (only) one least significant octet */ + *msg_ptr = (u8_t)value; + return ERR_OK; + } + p = p->next; + } + /* p == NULL, ofs >= plen */ + return ERR_ARG; +} + +/** + * Encodes s32_t integer into a pbuf chained ASN1 msg. + * + * @param p points to output pbuf to encode value into + * @param ofs points to the offset within the pbuf chain + * @param octets_needed encoding length (from snmp_asn1_enc_s32t_cnt()) + * @param value is the host order s32_t value to be encoded + * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode + * + * @see snmp_asn1_enc_s32t_cnt() + */ +err_t +snmp_asn1_enc_s32t(struct pbuf *p, u16_t ofs, u16_t octets_needed, s32_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; + + while (octets_needed > 1) + { + octets_needed--; + *msg_ptr = (u8_t)(value >> (octets_needed << 3)); + 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++; + } + } + /* (only) one least significant octet */ + *msg_ptr = (u8_t)value; + return ERR_OK; + } + p = p->next; + } + /* p == NULL, ofs >= plen */ + return ERR_ARG; +} + +/** + * Encodes object identifier into a pbuf chained ASN1 msg. + * + * @param p points to output pbuf to encode oid into + * @param ofs points to the offset within the pbuf chain + * @param ident_len object identifier array length + * @param ident points to object identifier array + * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode + */ +err_t +snmp_asn1_enc_oid(struct pbuf *p, u16_t ofs, u8_t ident_len, s32_t *ident) +{ + 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 (ident_len > 1) + { + if ((ident[0] == 1) && (ident[1] == 3)) + { + /* compressed (most common) prefix .iso.org */ + *msg_ptr = 0x2b; + } + else + { + /* calculate prefix */ + *msg_ptr = (u8_t)((ident[0] * 40) + ident[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++; + } + ident_len -= 2; + ident += 2; + } + else + { +/* @bug: allow empty varbinds for symmetry (we must decode them for getnext), allow partial compression?? */ + /* ident_len <= 1, at least we need zeroDotZero (0.0) (ident_len == 2) */ + return ERR_ARG; + } + while (ident_len > 0) + { + s32_t sub_id; + u8_t shift, tail; + + ident_len--; + sub_id = *ident; + tail = 0; + shift = 28; + while(shift > 0) + { + u8_t code; + + code = (u8_t)(sub_id >> shift); + if ((code != 0) || (tail != 0)) + { + tail = 1; + *msg_ptr = code | 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++; + } + } + shift -= 7; + } + *msg_ptr = (u8_t)sub_id & 0x7F; + if (ident_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++; + } + } + /* proceed to next sub-identifier */ + ident++; + } + return ERR_OK; + } + p = p->next; + } + /* p == NULL, ofs >= plen */ + return ERR_ARG; +} + +/** + * Encodes raw data (octet string, opaque) into a pbuf chained ASN1 msg. + * + * @param p points to output pbuf to encode raw data into + * @param ofs points to the offset within the pbuf chain + * @param raw_len raw data length + * @param raw points raw data + * @return ERR_OK if successfull, ERR_ARG if we can't (or won't) encode + */ +err_t +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 */