| /* $NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky Exp $ */ |
| |
| /* |
| * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Copyright (c) 1999-2004 The tcpdump.org project |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that: (1) source code distributions |
| * retain the above copyright notice and this paragraph in its entirety, (2) |
| * distributions including binary code include the above copyright notice and |
| * this paragraph in its entirety in the documentation or other materials |
| * provided with the distribution, and (3) all advertising materials mentioning |
| * features or use of this software display the following acknowledgement: |
| * ``This product includes software developed by the University of California, |
| * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of |
| * the University nor the names of its contributors may be used to endorse |
| * or promote products derived from this software without specific prior |
| * written permission. |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED |
| * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| */ |
| |
| #ifndef lint |
| static const char rcsid[] _U_ = |
| "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.135 2008-11-09 23:35:03 mcr Exp $ (LBL)"; |
| #else |
| __RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $"); |
| #endif |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include <tcpdump-stdinc.h> |
| |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| #include "interface.h" |
| #include "addrtoname.h" |
| #include "extract.h" |
| |
| #include "tcp.h" |
| |
| #include "ip.h" |
| #ifdef INET6 |
| #include "ip6.h" |
| #endif |
| #include "ipproto.h" |
| #include "rpc_auth.h" |
| #include "rpc_msg.h" |
| |
| #include "nameser.h" |
| |
| #ifdef HAVE_LIBCRYPTO |
| #include <openssl/md5.h> |
| #include <signature.h> |
| |
| static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp, |
| const u_char *data, int length, const u_char *rcvsig); |
| #endif |
| |
| static void print_tcp_rst_data(register const u_char *sp, u_int length); |
| |
| #define MAX_RST_DATA_LEN 30 |
| |
| |
| struct tha { |
| #ifndef INET6 |
| struct in_addr src; |
| struct in_addr dst; |
| #else |
| struct in6_addr src; |
| struct in6_addr dst; |
| #endif /*INET6*/ |
| u_int port; |
| }; |
| |
| struct tcp_seq_hash { |
| struct tcp_seq_hash *nxt; |
| struct tha addr; |
| tcp_seq seq; |
| tcp_seq ack; |
| }; |
| |
| #define TSEQ_HASHSIZE 919 |
| |
| /* These tcp optinos do not have the size octet */ |
| #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP) |
| |
| static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE]; |
| |
| struct tok tcp_flag_values[] = { |
| { TH_FIN, "F" }, |
| { TH_SYN, "S" }, |
| { TH_RST, "R" }, |
| { TH_PUSH, "P" }, |
| { TH_ACK, "." }, |
| { TH_URG, "U" }, |
| { TH_ECNECHO, "E" }, |
| { TH_CWR, "W" }, |
| { 0, NULL } |
| }; |
| |
| struct tok tcp_option_values[] = { |
| { TCPOPT_EOL, "eol" }, |
| { TCPOPT_NOP, "nop" }, |
| { TCPOPT_MAXSEG, "mss" }, |
| { TCPOPT_WSCALE, "wscale" }, |
| { TCPOPT_SACKOK, "sackOK" }, |
| { TCPOPT_SACK, "sack" }, |
| { TCPOPT_ECHO, "echo" }, |
| { TCPOPT_ECHOREPLY, "echoreply" }, |
| { TCPOPT_TIMESTAMP, "TS" }, |
| { TCPOPT_CC, "cc" }, |
| { TCPOPT_CCNEW, "ccnew" }, |
| { TCPOPT_CCECHO, "" }, |
| { TCPOPT_SIGNATURE, "md5" }, |
| { TCPOPT_AUTH, "enhanced auth" }, |
| { TCPOPT_UTO, "uto" }, |
| { 0, NULL } |
| }; |
| |
| static int tcp_cksum(register const struct ip *ip, |
| register const struct tcphdr *tp, |
| register u_int len) |
| { |
| return (nextproto4_cksum(ip, (const u_int8_t *)tp, len, |
| IPPROTO_TCP)); |
| } |
| |
| void |
| tcp_print(register const u_char *bp, register u_int length, |
| register const u_char *bp2, int fragmented) |
| { |
| register const struct tcphdr *tp; |
| register const struct ip *ip; |
| register u_char flags; |
| register u_int hlen; |
| register char ch; |
| u_int16_t sport, dport, win, urp; |
| u_int32_t seq, ack, thseq, thack; |
| u_int utoval; |
| int threv; |
| #ifdef INET6 |
| register const struct ip6_hdr *ip6; |
| #endif |
| |
| tp = (struct tcphdr *)bp; |
| ip = (struct ip *)bp2; |
| #ifdef INET6 |
| if (IP_V(ip) == 6) |
| ip6 = (struct ip6_hdr *)bp2; |
| else |
| ip6 = NULL; |
| #endif /*INET6*/ |
| ch = '\0'; |
| if (!TTEST(tp->th_dport)) { |
| (void)printf("%s > %s: [|tcp]", |
| ipaddr_string(&ip->ip_src), |
| ipaddr_string(&ip->ip_dst)); |
| return; |
| } |
| |
| sport = EXTRACT_16BITS(&tp->th_sport); |
| dport = EXTRACT_16BITS(&tp->th_dport); |
| |
| hlen = TH_OFF(tp) * 4; |
| |
| /* |
| * If data present, header length valid, and NFS port used, |
| * assume NFS. |
| * Pass offset of data plus 4 bytes for RPC TCP msg length |
| * to NFS print routines. |
| */ |
| if (!qflag && hlen >= sizeof(*tp) && hlen <= length && |
| (length - hlen) >= 4) { |
| u_char *fraglenp; |
| u_int32_t fraglen; |
| register struct sunrpc_msg *rp; |
| enum sunrpc_msg_type direction; |
| |
| fraglenp = (u_char *)tp + hlen; |
| if (TTEST2(*fraglenp, 4)) { |
| fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF; |
| if (fraglen > (length - hlen) - 4) |
| fraglen = (length - hlen) - 4; |
| rp = (struct sunrpc_msg *)(fraglenp + 4); |
| if (TTEST(rp->rm_direction)) { |
| direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction); |
| if (dport == NFS_PORT && |
| direction == SUNRPC_CALL) { |
| nfsreq_print((u_char *)rp, fraglen, |
| (u_char *)ip); |
| return; |
| } |
| if (sport == NFS_PORT && |
| direction == SUNRPC_REPLY) { |
| nfsreply_print((u_char *)rp, fraglen, |
| (u_char *)ip); |
| return; |
| } |
| } |
| } |
| } |
| #ifdef INET6 |
| if (ip6) { |
| if (ip6->ip6_nxt == IPPROTO_TCP) { |
| (void)printf("%s.%s > %s.%s: ", |
| ip6addr_string(&ip6->ip6_src), |
| tcpport_string(sport), |
| ip6addr_string(&ip6->ip6_dst), |
| tcpport_string(dport)); |
| } else { |
| (void)printf("%s > %s: ", |
| tcpport_string(sport), tcpport_string(dport)); |
| } |
| } else |
| #endif /*INET6*/ |
| { |
| if (ip->ip_p == IPPROTO_TCP) { |
| (void)printf("%s.%s > %s.%s: ", |
| ipaddr_string(&ip->ip_src), |
| tcpport_string(sport), |
| ipaddr_string(&ip->ip_dst), |
| tcpport_string(dport)); |
| } else { |
| (void)printf("%s > %s: ", |
| tcpport_string(sport), tcpport_string(dport)); |
| } |
| } |
| |
| if (hlen < sizeof(*tp)) { |
| (void)printf(" tcp %d [bad hdr length %u - too short, < %lu]", |
| length - hlen, hlen, (unsigned long)sizeof(*tp)); |
| return; |
| } |
| |
| TCHECK(*tp); |
| |
| seq = EXTRACT_32BITS(&tp->th_seq); |
| ack = EXTRACT_32BITS(&tp->th_ack); |
| win = EXTRACT_16BITS(&tp->th_win); |
| urp = EXTRACT_16BITS(&tp->th_urp); |
| |
| if (qflag) { |
| (void)printf("tcp %d", length - hlen); |
| if (hlen > length) { |
| (void)printf(" [bad hdr length %u - too long, > %u]", |
| hlen, length); |
| } |
| return; |
| } |
| |
| flags = tp->th_flags; |
| printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags)); |
| |
| if (!Sflag && (flags & TH_ACK)) { |
| register struct tcp_seq_hash *th; |
| const void *src, *dst; |
| register int rev; |
| struct tha tha; |
| /* |
| * Find (or record) the initial sequence numbers for |
| * this conversation. (we pick an arbitrary |
| * collating order so there's only one entry for |
| * both directions). |
| */ |
| #ifdef INET6 |
| rev = 0; |
| if (ip6) { |
| src = &ip6->ip6_src; |
| dst = &ip6->ip6_dst; |
| if (sport > dport) |
| rev = 1; |
| else if (sport == dport) { |
| if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0) |
| rev = 1; |
| } |
| if (rev) { |
| memcpy(&tha.src, dst, sizeof ip6->ip6_dst); |
| memcpy(&tha.dst, src, sizeof ip6->ip6_src); |
| tha.port = dport << 16 | sport; |
| } else { |
| memcpy(&tha.dst, dst, sizeof ip6->ip6_dst); |
| memcpy(&tha.src, src, sizeof ip6->ip6_src); |
| tha.port = sport << 16 | dport; |
| } |
| } else { |
| /* |
| * Zero out the tha structure; the src and dst |
| * fields are big enough to hold an IPv6 |
| * address, but we only have IPv4 addresses |
| * and thus must clear out the remaining 124 |
| * bits. |
| * |
| * XXX - should we just clear those bytes after |
| * copying the IPv4 addresses, rather than |
| * zeroing out the entire structure and then |
| * overwriting some of the zeroes? |
| * |
| * XXX - this could fail if we see TCP packets |
| * with an IPv6 address with the lower 124 bits |
| * all zero and also see TCP packes with an |
| * IPv4 address with the same 32 bits as the |
| * upper 32 bits of the IPv6 address in question. |
| * Can that happen? Is it likely enough to be |
| * an issue? |
| */ |
| memset(&tha, 0, sizeof(tha)); |
| src = &ip->ip_src; |
| dst = &ip->ip_dst; |
| if (sport > dport) |
| rev = 1; |
| else if (sport == dport) { |
| if (memcmp(src, dst, sizeof ip->ip_dst) > 0) |
| rev = 1; |
| } |
| if (rev) { |
| memcpy(&tha.src, dst, sizeof ip->ip_dst); |
| memcpy(&tha.dst, src, sizeof ip->ip_src); |
| tha.port = dport << 16 | sport; |
| } else { |
| memcpy(&tha.dst, dst, sizeof ip->ip_dst); |
| memcpy(&tha.src, src, sizeof ip->ip_src); |
| tha.port = sport << 16 | dport; |
| } |
| } |
| #else |
| rev = 0; |
| src = &ip->ip_src; |
| dst = &ip->ip_dst; |
| if (sport > dport) |
| rev = 1; |
| else if (sport == dport) { |
| if (memcmp(src, dst, sizeof ip->ip_dst) > 0) |
| rev = 1; |
| } |
| if (rev) { |
| memcpy(&tha.src, dst, sizeof ip->ip_dst); |
| memcpy(&tha.dst, src, sizeof ip->ip_src); |
| tha.port = dport << 16 | sport; |
| } else { |
| memcpy(&tha.dst, dst, sizeof ip->ip_dst); |
| memcpy(&tha.src, src, sizeof ip->ip_src); |
| tha.port = sport << 16 | dport; |
| } |
| #endif |
| |
| threv = rev; |
| for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE]; |
| th->nxt; th = th->nxt) |
| if (memcmp((char *)&tha, (char *)&th->addr, |
| sizeof(th->addr)) == 0) |
| break; |
| |
| if (!th->nxt || (flags & TH_SYN)) { |
| /* didn't find it or new conversation */ |
| if (th->nxt == NULL) { |
| th->nxt = (struct tcp_seq_hash *) |
| calloc(1, sizeof(*th)); |
| if (th->nxt == NULL) |
| error("tcp_print: calloc"); |
| } |
| th->addr = tha; |
| if (rev) |
| th->ack = seq, th->seq = ack - 1; |
| else |
| th->seq = seq, th->ack = ack - 1; |
| } else { |
| if (rev) |
| seq -= th->ack, ack -= th->seq; |
| else |
| seq -= th->seq, ack -= th->ack; |
| } |
| |
| thseq = th->seq; |
| thack = th->ack; |
| } else { |
| /*fool gcc*/ |
| thseq = thack = threv = 0; |
| } |
| if (hlen > length) { |
| (void)printf(" [bad hdr length %u - too long, > %u]", |
| hlen, length); |
| return; |
| } |
| |
| if (vflag && !Kflag && !fragmented) { |
| /* Check the checksum, if possible. */ |
| u_int16_t sum, tcp_sum; |
| |
| if (IP_V(ip) == 4) { |
| if (TTEST2(tp->th_sport, length)) { |
| sum = tcp_cksum(ip, tp, length); |
| tcp_sum = EXTRACT_16BITS(&tp->th_sum); |
| |
| (void)printf(", cksum 0x%04x", tcp_sum); |
| if (sum != 0) |
| (void)printf(" (incorrect -> 0x%04x)", |
| in_cksum_shouldbe(tcp_sum, sum)); |
| else |
| (void)printf(" (correct)"); |
| } |
| } |
| #ifdef INET6 |
| else if (IP_V(ip) == 6 && ip6->ip6_plen) { |
| if (TTEST2(tp->th_sport, length)) { |
| sum = nextproto6_cksum(ip6, (const u_int8_t *)tp, length, IPPROTO_TCP); |
| tcp_sum = EXTRACT_16BITS(&tp->th_sum); |
| |
| (void)printf(", cksum 0x%04x", tcp_sum); |
| if (sum != 0) |
| (void)printf(" (incorrect -> 0x%04x)", |
| in_cksum_shouldbe(tcp_sum, sum)); |
| else |
| (void)printf(" (correct)"); |
| |
| } |
| } |
| #endif |
| } |
| |
| length -= hlen; |
| if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) { |
| (void)printf(", seq %u", seq); |
| |
| if (length > 0) { |
| (void)printf(":%u", seq + length); |
| } |
| } |
| |
| if (flags & TH_ACK) { |
| (void)printf(", ack %u", ack); |
| } |
| |
| (void)printf(", win %d", win); |
| |
| if (flags & TH_URG) |
| (void)printf(", urg %d", urp); |
| /* |
| * Handle any options. |
| */ |
| if (hlen > sizeof(*tp)) { |
| register const u_char *cp; |
| register u_int i, opt, datalen; |
| register u_int len; |
| |
| hlen -= sizeof(*tp); |
| cp = (const u_char *)tp + sizeof(*tp); |
| printf(", options ["); |
| while (hlen > 0) { |
| if (ch != '\0') |
| putchar(ch); |
| TCHECK(*cp); |
| opt = *cp++; |
| if (ZEROLENOPT(opt)) |
| len = 1; |
| else { |
| TCHECK(*cp); |
| len = *cp++; /* total including type, len */ |
| if (len < 2 || len > hlen) |
| goto bad; |
| --hlen; /* account for length byte */ |
| } |
| --hlen; /* account for type byte */ |
| datalen = 0; |
| |
| /* Bail if "l" bytes of data are not left or were not captured */ |
| #define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); } |
| |
| |
| printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt)); |
| |
| switch (opt) { |
| |
| case TCPOPT_MAXSEG: |
| datalen = 2; |
| LENCHECK(datalen); |
| (void)printf(" %u", EXTRACT_16BITS(cp)); |
| break; |
| |
| case TCPOPT_WSCALE: |
| datalen = 1; |
| LENCHECK(datalen); |
| (void)printf(" %u", *cp); |
| break; |
| |
| case TCPOPT_SACK: |
| datalen = len - 2; |
| if (datalen % 8 != 0) { |
| (void)printf("malformed sack"); |
| } else { |
| u_int32_t s, e; |
| |
| (void)printf(" %d ", datalen / 8); |
| for (i = 0; i < datalen; i += 8) { |
| LENCHECK(i + 4); |
| s = EXTRACT_32BITS(cp + i); |
| LENCHECK(i + 8); |
| e = EXTRACT_32BITS(cp + i + 4); |
| if (threv) { |
| s -= thseq; |
| e -= thseq; |
| } else { |
| s -= thack; |
| e -= thack; |
| } |
| (void)printf("{%u:%u}", s, e); |
| } |
| } |
| break; |
| |
| case TCPOPT_CC: |
| case TCPOPT_CCNEW: |
| case TCPOPT_CCECHO: |
| case TCPOPT_ECHO: |
| case TCPOPT_ECHOREPLY: |
| |
| /* |
| * those options share their semantics. |
| * fall through |
| */ |
| datalen = 4; |
| LENCHECK(datalen); |
| (void)printf(" %u", EXTRACT_32BITS(cp)); |
| break; |
| |
| case TCPOPT_TIMESTAMP: |
| datalen = 8; |
| LENCHECK(datalen); |
| (void)printf(" val %u ecr %u", |
| EXTRACT_32BITS(cp), |
| EXTRACT_32BITS(cp + 4)); |
| break; |
| |
| case TCPOPT_SIGNATURE: |
| datalen = TCP_SIGLEN; |
| LENCHECK(datalen); |
| #ifdef HAVE_LIBCRYPTO |
| switch (tcp_verify_signature(ip, tp, |
| bp + TH_OFF(tp) * 4, length, cp)) { |
| |
| case SIGNATURE_VALID: |
| (void)printf("valid"); |
| break; |
| |
| case SIGNATURE_INVALID: |
| (void)printf("invalid"); |
| break; |
| |
| case CANT_CHECK_SIGNATURE: |
| (void)printf("can't check - "); |
| for (i = 0; i < TCP_SIGLEN; ++i) |
| (void)printf("%02x", cp[i]); |
| break; |
| } |
| #else |
| for (i = 0; i < TCP_SIGLEN; ++i) |
| (void)printf("%02x", cp[i]); |
| #endif |
| break; |
| |
| case TCPOPT_AUTH: |
| (void)printf("keyid %d", *cp++); |
| datalen = len - 3; |
| for (i = 0; i < datalen; ++i) { |
| LENCHECK(i); |
| (void)printf("%02x", cp[i]); |
| } |
| break; |
| |
| |
| case TCPOPT_EOL: |
| case TCPOPT_NOP: |
| case TCPOPT_SACKOK: |
| /* |
| * Nothing interesting. |
| * fall through |
| */ |
| break; |
| |
| case TCPOPT_UTO: |
| datalen = 2; |
| LENCHECK(datalen); |
| utoval = EXTRACT_16BITS(cp); |
| (void)printf("0x%x", utoval); |
| if (utoval & 0x0001) |
| utoval = (utoval >> 1) * 60; |
| else |
| utoval >>= 1; |
| (void)printf(" %u", utoval); |
| break; |
| |
| default: |
| datalen = len - 2; |
| for (i = 0; i < datalen; ++i) { |
| LENCHECK(i); |
| (void)printf("%02x", cp[i]); |
| } |
| break; |
| } |
| |
| /* Account for data printed */ |
| cp += datalen; |
| hlen -= datalen; |
| |
| /* Check specification against observed length */ |
| ++datalen; /* option octet */ |
| if (!ZEROLENOPT(opt)) |
| ++datalen; /* size octet */ |
| if (datalen != len) |
| (void)printf("[len %d]", len); |
| ch = ','; |
| if (opt == TCPOPT_EOL) |
| break; |
| } |
| putchar(']'); |
| } |
| |
| /* |
| * Print length field before crawling down the stack. |
| */ |
| printf(", length %u", length); |
| |
| if (length <= 0) |
| return; |
| |
| /* |
| * Decode payload if necessary. |
| */ |
| bp += TH_OFF(tp) * 4; |
| if ((flags & TH_RST) && vflag) { |
| print_tcp_rst_data(bp, length); |
| return; |
| } |
| |
| if (sport == TELNET_PORT || dport == TELNET_PORT) { |
| if (!qflag && vflag) |
| telnet_print(bp, length); |
| } else if (sport == BGP_PORT || dport == BGP_PORT) |
| bgp_print(bp, length); |
| else if (sport == PPTP_PORT || dport == PPTP_PORT) |
| pptp_print(bp); |
| #ifdef TCPDUMP_DO_SMB |
| else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT) |
| nbt_tcp_print(bp, length); |
| else if (sport == SMB_PORT || dport == SMB_PORT) |
| smb_tcp_print(bp, length); |
| #endif |
| else if (sport == BEEP_PORT || dport == BEEP_PORT) |
| beep_print(bp, length); |
| else if (length > 2 && |
| (sport == NAMESERVER_PORT || dport == NAMESERVER_PORT || |
| sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) { |
| /* |
| * TCP DNS query has 2byte length at the head. |
| * XXX packet could be unaligned, it can go strange |
| */ |
| ns_print(bp + 2, length - 2, 0); |
| } else if (sport == MSDP_PORT || dport == MSDP_PORT) { |
| msdp_print(bp, length); |
| } else if (sport == RPKI_RTR_PORT || dport == RPKI_RTR_PORT) { |
| rpki_rtr_print(bp, length); |
| } |
| else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) { |
| ldp_print(bp, length); |
| } |
| |
| return; |
| bad: |
| fputs("[bad opt]", stdout); |
| if (ch != '\0') |
| putchar('>'); |
| return; |
| trunc: |
| fputs("[|tcp]", stdout); |
| if (ch != '\0') |
| putchar('>'); |
| } |
| |
| /* |
| * RFC1122 says the following on data in RST segments: |
| * |
| * 4.2.2.12 RST Segment: RFC-793 Section 3.4 |
| * |
| * A TCP SHOULD allow a received RST segment to include data. |
| * |
| * DISCUSSION |
| * It has been suggested that a RST segment could contain |
| * ASCII text that encoded and explained the cause of the |
| * RST. No standard has yet been established for such |
| * data. |
| * |
| */ |
| |
| static void |
| print_tcp_rst_data(register const u_char *sp, u_int length) |
| { |
| int c; |
| |
| if (TTEST2(*sp, length)) |
| printf(" [RST"); |
| else |
| printf(" [!RST"); |
| if (length > MAX_RST_DATA_LEN) { |
| length = MAX_RST_DATA_LEN; /* can use -X for longer */ |
| putchar('+'); /* indicate we truncate */ |
| } |
| putchar(' '); |
| while (length-- && sp <= snapend) { |
| c = *sp++; |
| safeputchar(c); |
| } |
| putchar(']'); |
| } |
| |
| #ifdef HAVE_LIBCRYPTO |
| static int |
| tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp, |
| const u_char *data, int length, const u_char *rcvsig) |
| { |
| struct tcphdr tp1; |
| u_char sig[TCP_SIGLEN]; |
| char zero_proto = 0; |
| MD5_CTX ctx; |
| u_int16_t savecsum, tlen; |
| #ifdef INET6 |
| struct ip6_hdr *ip6; |
| u_int32_t len32; |
| u_int8_t nxt; |
| #endif |
| |
| if (data + length > snapend) { |
| printf("snaplen too short, "); |
| return (CANT_CHECK_SIGNATURE); |
| } |
| |
| tp1 = *tp; |
| |
| if (sigsecret == NULL) { |
| printf("shared secret not supplied with -M, "); |
| return (CANT_CHECK_SIGNATURE); |
| } |
| |
| MD5_Init(&ctx); |
| /* |
| * Step 1: Update MD5 hash with IP pseudo-header. |
| */ |
| if (IP_V(ip) == 4) { |
| MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src)); |
| MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst)); |
| MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto)); |
| MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p)); |
| tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4; |
| tlen = htons(tlen); |
| MD5_Update(&ctx, (char *)&tlen, sizeof(tlen)); |
| #ifdef INET6 |
| } else if (IP_V(ip) == 6) { |
| ip6 = (struct ip6_hdr *)ip; |
| MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src)); |
| MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst)); |
| len32 = htonl(EXTRACT_16BITS(&ip6->ip6_plen)); |
| MD5_Update(&ctx, (char *)&len32, sizeof(len32)); |
| nxt = 0; |
| MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); |
| MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); |
| MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); |
| nxt = IPPROTO_TCP; |
| MD5_Update(&ctx, (char *)&nxt, sizeof(nxt)); |
| #endif |
| } else { |
| #ifdef INET6 |
| printf("IP version not 4 or 6, "); |
| #else |
| printf("IP version not 4, "); |
| #endif |
| return (CANT_CHECK_SIGNATURE); |
| } |
| |
| /* |
| * Step 2: Update MD5 hash with TCP header, excluding options. |
| * The TCP checksum must be set to zero. |
| */ |
| savecsum = tp1.th_sum; |
| tp1.th_sum = 0; |
| MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr)); |
| tp1.th_sum = savecsum; |
| /* |
| * Step 3: Update MD5 hash with TCP segment data, if present. |
| */ |
| if (length > 0) |
| MD5_Update(&ctx, data, length); |
| /* |
| * Step 4: Update MD5 hash with shared secret. |
| */ |
| MD5_Update(&ctx, sigsecret, strlen(sigsecret)); |
| MD5_Final(sig, &ctx); |
| |
| if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0) |
| return (SIGNATURE_VALID); |
| else |
| return (SIGNATURE_INVALID); |
| } |
| #endif /* HAVE_LIBCRYPTO */ |
| |
| /* |
| * Local Variables: |
| * c-style: whitesmith |
| * c-basic-offset: 8 |
| * End: |
| */ |
