/* Copyright (C) 2007-2010 Open Information Security Foundation * * You can copy, redistribute or modify this Program under the terms of * the GNU General Public License version 2 as published by the Free * Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * version 2 along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301, USA. */ /** * \file * * \author Victor Julien * \author Brian Rectanus */ #ifndef __DECODE_IPV4_H__ #define __DECODE_IPV4_H__ #define IPV4_HEADER_LEN 20 /**< Header length */ #define IPV4_OPTMAX 40 /**< Max options length */ #define IPV4_MAXPACKET_LEN 65535 /**< Maximum packet size */ /** IP Option Types */ #define IPV4_OPT_EOL 0x00 /**< Option: End of List */ #define IPV4_OPT_NOP 0x01 /**< Option: No op */ #define IPV4_OPT_RR 0x07 /**< Option: Record Route */ #define IPV4_OPT_QS 0x19 /**< Option: Quick Start */ #define IPV4_OPT_TS 0x44 /**< Option: Timestamp */ #define IPV4_OPT_SEC 0x82 /**< Option: Security */ #define IPV4_OPT_LSRR 0x83 /**< Option: Loose Source Route */ #define IPV4_OPT_CIPSO 0x86 /**< Option: Commercial IP Security */ #define IPV4_OPT_SID 0x88 /**< Option: Stream Identifier */ #define IPV4_OPT_SSRR 0x89 /**< Option: Strict Source Route */ #define IPV4_OPT_RTRALT 0x94 /**< Option: Router Alert */ /** IP Option Lengths (fixed) */ #define IPV4_OPT_SEC_LEN 11 /**< SEC Option Fixed Length */ #define IPV4_OPT_SID_LEN 4 /**< SID Option Fixed Length */ #define IPV4_OPT_RTRALT_LEN 4 /**< RTRALT Option Fixed Length */ /** IP Option Lengths (variable) */ #define IPV4_OPT_ROUTE_MIN 3 /**< RR, SRR, LTRR Option Min Length */ #define IPV4_OPT_QS_MIN 8 /**< QS Option Min Length */ #define IPV4_OPT_TS_MIN 5 /**< TS Option Min Length */ #define IPV4_OPT_CIPSO_MIN 10 /**< CIPSO Option Min Length */ /** IP Option fields */ #define IPV4_OPTS ip4vars.ip_opts #define IPV4_OPTS_CNT ip4vars.ip_opt_cnt typedef struct IPV4Opt_ { /** \todo We may want to break type up into its 3 fields * as the reassembler may want to know which options * must be copied to each fragment. */ uint8_t type; /**< option type */ uint8_t len; /**< option length (type+len+data) */ uint8_t *data; /**< option data */ } IPV4Opt; typedef struct IPV4Hdr_ { uint8_t ip_verhl; /**< version & header length */ uint8_t ip_tos; /**< type of service */ uint16_t ip_len; /**< length */ uint16_t ip_id; /**< id */ uint16_t ip_off; /**< frag offset */ uint8_t ip_ttl; /**< time to live */ uint8_t ip_proto; /**< protocol (tcp, udp, etc) */ uint16_t ip_csum; /**< checksum */ struct in_addr ip_src;/**< source address */ struct in_addr ip_dst;/**< destination address */ } IPV4Hdr; #define IPV4_GET_RAW_VER(ip4h) (((ip4h)->ip_verhl & 0xf0) >> 4) #define IPV4_GET_RAW_HLEN(ip4h) ((ip4h)->ip_verhl & 0x0f) #define IPV4_GET_RAW_IPTOS(ip4h) ((ip4h)->ip_tos) #define IPV4_GET_RAW_IPLEN(ip4h) ((ip4h)->ip_len) #define IPV4_GET_RAW_IPID(ip4h) ((ip4h)->ip_id) #define IPV4_GET_RAW_IPOFFSET(ip4h) ((ip4h)->ip_off) #define IPV4_GET_RAW_IPTTL(ip4h) ((ip4h)->ip_ttl) #define IPV4_GET_RAW_IPPROTO(ip4h) ((ip4h)->ip_proto) #define IPV4_GET_RAW_IPSRC(ip4h) ((ip4h)->ip_src) #define IPV4_GET_RAW_IPDST(ip4h) ((ip4h)->ip_dst) /** return the raw (directly from the header) src ip as uint32_t */ #define IPV4_GET_RAW_IPSRC_U32(ip4h) (uint32_t)((ip4h)->ip_src.s_addr) /** return the raw (directly from the header) dst ip as uint32_t */ #define IPV4_GET_RAW_IPDST_U32(ip4h) (uint32_t)((ip4h)->ip_dst.s_addr) /* we need to change them as well as get them */ #define IPV4_SET_RAW_VER(ip4h, value) ((ip4h)->ip_verhl = (((ip4h)->ip_verhl & 0x0f) | (value << 4))) #define IPV4_SET_RAW_HLEN(ip4h, value) ((ip4h)->ip_verhl = (((ip4h)->ip_verhl & 0xf0) | (value & 0x0f))) #define IPV4_SET_RAW_IPTOS(ip4h, value) ((ip4h)->ip_tos = value) #define IPV4_SET_RAW_IPLEN(ip4h, value) ((ip4h)->ip_len = value) #define IPV4_SET_RAW_IPPROTO(ip4h, value) ((ip4h)->ip_proto = value) /* this is enough since noone will access the cache without first * checking the flags */ #define IPV4_CACHE_INIT(p) (p)->ip4c.flags = 0 /* ONLY call these functions after making sure that: * 1. p->ip4h is set * 2. p->ip4h is valid (len is correct) * 3. cache is initialized */ #define IPV4_GET_VER(p) \ ((p)->ip4c.flags & IPV4_CACHE_VER ? \ (p)->ip4c.ver : ((p)->ip4c.flags |= IPV4_CACHE_VER, (p)->ip4c.ver = IPV4_GET_RAW_VER((p)->ip4h))) #define IPV4_GET_HLEN(p) \ ((p)->ip4c.flags & IPV4_CACHE_HLEN ? \ (p)->ip4c.hl : ((p)->ip4c.flags |= IPV4_CACHE_HLEN, (p)->ip4c.hl = IPV4_GET_RAW_HLEN((p)->ip4h) << 2)) #define IPV4_GET_IPTOS(p) \ IPV4_GET_RAW_IPTOS((p)->ip4h) #define IPV4_GET_IPLEN(p) \ ((p)->ip4c.flags & IPV4_CACHE_IPLEN ? \ (p)->ip4c.ip_len : ((p)->ip4c.flags |= IPV4_CACHE_IPLEN, (p)->ip4c.ip_len = ntohs(IPV4_GET_RAW_IPLEN((p)->ip4h)))) #define IPV4_GET_IPID(p) \ ((p)->ip4c.flags & IPV4_CACHE_IPID ? \ (p)->ip4c.ip_id : ((p)->ip4c.flags |= IPV4_CACHE_IPID, (p)->ip4c.ip_id = ntohs(IPV4_GET_RAW_IPID((p)->ip4h)))) /* _IPV4_GET_IPOFFSET: get the content of the offset header field in host order */ #define _IPV4_GET_IPOFFSET(p) \ ((p)->ip4c.flags & IPV4_CACHE__IPOFF ? \ (p)->ip4c._ip_off : ((p)->ip4c.flags |= IPV4_CACHE__IPOFF, (p)->ip4c._ip_off = ntohs(IPV4_GET_RAW_IPOFFSET((p)->ip4h)))) /* IPV4_GET_IPOFFSET: get the final offset */ #define IPV4_GET_IPOFFSET(p) \ ((p)->ip4c.flags & IPV4_CACHE_IPOFF ? \ (p)->ip4c.ip_off : ((p)->ip4c.flags |= IPV4_CACHE_IPOFF, (p)->ip4c.ip_off = _IPV4_GET_IPOFFSET(p) & 0x1fff)) /* IPV4_GET_RF: get the RF flag. Use _IPV4_GET_IPOFFSET to save a ntohs call. */ #define IPV4_GET_RF(p) \ ((p)->ip4c.flags & IPV4_CACHE_RF ? \ (p)->ip4c.rf : ((p)->ip4c.flags |= IPV4_CACHE_RF, (p)->ip4c.rf = (uint8_t)((_IPV4_GET_IPOFFSET((p)) & 0x8000) >> 15))) /* IPV4_GET_DF: get the DF flag. Use _IPV4_GET_IPOFFSET to save a ntohs call. */ #define IPV4_GET_DF(p) \ ((p)->ip4c.flags & IPV4_CACHE_DF ? \ (p)->ip4c.df : ((p)->ip4c.flags |= IPV4_CACHE_DF, (p)->ip4c.df = (uint8_t)((_IPV4_GET_IPOFFSET((p)) & 0x4000) >> 14))) /* IPV4_GET_MF: get the MF flag. Use _IPV4_GET_IPOFFSET to save a ntohs call. */ #define IPV4_GET_MF(p) \ ((p)->ip4c.flags & IPV4_CACHE_MF ? \ (p)->ip4c.mf : ((p)->ip4c.flags |= IPV4_CACHE_MF, (p)->ip4c.mf = (uint8_t)((_IPV4_GET_IPOFFSET((p)) & 0x2000) >> 13))) #define IPV4_GET_IPTTL(p) \ IPV4_GET_RAW_IPTTL(p->ip4h) #define IPV4_GET_IPPROTO(p) \ ((p)->ip4c.flags & IPV4_CACHE_IPPROTO ? \ (p)->ip4c.ip_proto : ((p)->ip4c.flags |= IPV4_CACHE_IPPROTO, (p)->ip4c.ip_proto = IPV4_GET_RAW_IPPROTO((p)->ip4h))) #define IPV4_CACHE_VER 0x0001 /* 1 */ #define IPV4_CACHE_HLEN 0x0002 /* 2 */ #define IPV4_CACHE_IPTOS 0x0004 /* 4 */ #define IPV4_CACHE_IPLEN 0x0008 /* 8 */ #define IPV4_CACHE_IPID 0x0010 /* 16 */ #define IPV4_CACHE_IPOFF 0x0020 /* 32 */ #define IPV4_CACHE__IPOFF 0x0040 /* 64 */ #define IPV4_CACHE_RF 0x0080 /* 128*/ #define IPV4_CACHE_DF 0x0100 /* 256 */ #define IPV4_CACHE_MF 0x0200 /* 512 */ #define IPV4_CACHE_IPTTL 0x0400 /* 1024*/ #define IPV4_CACHE_IPPROTO 0x0800 /* 2048 */ /** * IPv4 decoder cache * * Used for storing parsed values. */ typedef struct IPV4Cache_ { uint16_t flags; uint8_t ver; uint8_t hl; uint8_t ip_tos; /* type of service */ uint16_t ip_len; /* datagram length */ uint16_t ip_id; /* identification */ uint16_t ip_off; /* fragment offset */ uint16_t _ip_off; /* fragment offset - full field value, host order*/ uint8_t rf; uint8_t df; uint8_t mf; uint8_t ip_ttl; /* time to live field */ uint8_t ip_proto; /* datagram protocol */ uint16_t ip_csum; /* checksum */ int32_t comp_csum; /* checksum computed over the ipv4 packet */ uint32_t ip_src_u32; /* source IP */ uint32_t ip_dst_u32; /* dest IP */ } IPV4Cache; #define CLEAR_IPV4_PACKET(p) do { \ (p)->ip4h = NULL; \ (p)->ip4vars.ip_opt_len = 0; \ (p)->ip4vars.ip_opt_cnt = 0; \ (p)->ip4vars.o_rr = NULL; \ (p)->ip4vars.o_qs = NULL; \ (p)->ip4vars.o_ts = NULL; \ (p)->ip4vars.o_sec = NULL; \ (p)->ip4vars.o_lsrr = NULL; \ (p)->ip4vars.o_cipso = NULL; \ (p)->ip4vars.o_sid = NULL; \ (p)->ip4vars.o_ssrr = NULL; \ (p)->ip4vars.o_rtralt = NULL; \ (p)->ip4c.flags = 0; \ (p)->ip4c.ver = 0; \ (p)->ip4c.hl = 0; \ (p)->ip4c.ip_tos = 0; \ (p)->ip4c.ip_len = 0; \ (p)->ip4c.ip_id = 0; \ (p)->ip4c.ip_off = 0; \ (p)->ip4c._ip_off = 0; \ (p)->ip4c.rf = 0; \ (p)->ip4c.df = 0; \ (p)->ip4c.mf = 0; \ (p)->ip4c.ip_ttl = 0; \ (p)->ip4c.ip_proto = 0; \ (p)->ip4c.ip_csum = 0; \ (p)->ip4c.comp_csum = 0; \ (p)->ip4c.ip_src_u32 = 0; \ (p)->ip4c.ip_dst_u32 = 0; \ } while (0) /* helper structure with parsed ipv4 info */ typedef struct IPV4Vars_ { uint8_t ip_opt_len; IPV4Opt ip_opts[IPV4_OPTMAX]; uint8_t ip_opt_cnt; /* These are here for direct access and dup tracking */ IPV4Opt *o_rr; IPV4Opt *o_qs; IPV4Opt *o_ts; IPV4Opt *o_sec; IPV4Opt *o_lsrr; IPV4Opt *o_cipso; IPV4Opt *o_sid; IPV4Opt *o_ssrr; IPV4Opt *o_rtralt; } IPV4Vars; void DecodeIPV4RegisterTests(void); /** ----- Inline functions ----- */ static inline uint16_t IPV4CalculateChecksum(uint16_t *, uint16_t); /** * \brief Calculates the checksum for the IP packet * * \param pkt Pointer to the start of the IP packet * \param hlen Length of the IP header * * \retval csum Checksum for the IP packet */ static inline uint16_t IPV4CalculateChecksum(uint16_t *pkt, uint16_t hlen) { uint32_t csum = pkt[0]; csum += pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[6] + pkt[7] + pkt[8] + pkt[9]; hlen -= 20; pkt += 10; if (hlen == 0) { ; } if (hlen == 4) csum += pkt[0] + pkt[1]; else if (hlen == 8) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3]; else if (hlen == 12) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5]; else if (hlen == 16) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] + pkt[7]; else if (hlen == 20) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] + pkt[7] + pkt[8] + pkt[9]; else if (hlen == 24) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] + pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11]; else if (hlen == 28) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] + pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13]; else if (hlen == 32) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] + pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] + pkt[14] + pkt[15]; if (hlen == 36) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] + pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] + pkt[14] + pkt[15] + pkt[16] + pkt[17]; if (hlen == 40) csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] + pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] + pkt[14] + pkt[15] + pkt[16] + pkt[17] + pkt[18] + pkt[19]; csum = (csum >> 16) + (csum & 0x0000FFFF); return (uint16_t) ~csum; } #endif /* __DECODE_IPV4_H__ */