Used in Live Traffic Update Nokia LCD Display Project
Fork of NetServices by
lwip/core/snmp/asn1_enc.c
- Committer:
- rrajan8
- Date:
- 2013-03-06
- Revision:
- 8:92b57208ab99
- Parent:
- 0:ac1725ba162c
File content as of revision 8:92b57208ab99:
/** * @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 */