/* 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. */ /* \summary: TCP printer */ #include #ifndef lint __RCSID("$NetBSD: print-tcp.c,v 1.12 2024/09/02 16:15:33 christos Exp $"); #endif #include #include "netdissect-stdinc.h" #include #include #include "netdissect.h" #include "addrtoname.h" #include "extract.h" #include "diag-control.h" #include "tcp.h" #include "ip.h" #include "ip6.h" #include "ipproto.h" #include "rpc_auth.h" #include "rpc_msg.h" #ifdef HAVE_LIBCRYPTO #include #include "signature.h" static int tcp_verify_signature(netdissect_options *ndo, const struct ip *ip, const struct tcphdr *tp, const u_char *data, u_int length, const u_char *rcvsig); #endif static void print_tcp_rst_data(netdissect_options *, const u_char *sp, u_int length); static void print_tcp_fastopen_option(netdissect_options *ndo, const u_char *cp, u_int datalen, int exp); #define MAX_RST_DATA_LEN 30 struct tha { nd_ipv4 src; nd_ipv4 dst; u_int port; }; struct tcp_seq_hash { struct tcp_seq_hash *nxt; struct tha addr; uint32_t seq; uint32_t ack; }; struct tha6 { nd_ipv6 src; nd_ipv6 dst; u_int port; }; struct tcp_seq_hash6 { struct tcp_seq_hash6 *nxt; struct tha6 addr; uint32_t seq; uint32_t ack; }; #define TSEQ_HASHSIZE 919 /* These tcp options do not have the size octet */ #define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP) static struct tcp_seq_hash tcp_seq_hash4[TSEQ_HASHSIZE]; static struct tcp_seq_hash6 tcp_seq_hash6[TSEQ_HASHSIZE]; static const 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 } }; static const 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, "ccecho" }, { TCPOPT_SIGNATURE, "md5" }, { TCPOPT_SCPS, "scps" }, { TCPOPT_UTO, "uto" }, { TCPOPT_TCPAO, "tcp-ao" }, { TCPOPT_MPTCP, "mptcp" }, { TCPOPT_FASTOPEN, "tfo" }, { TCPOPT_EXPERIMENT2, "exp" }, { 0, NULL } }; static uint16_t tcp_cksum(netdissect_options *ndo, const struct ip *ip, const struct tcphdr *tp, u_int len) { return nextproto4_cksum(ndo, ip, (const uint8_t *)tp, len, len, IPPROTO_TCP); } static uint16_t tcp6_cksum(netdissect_options *ndo, const struct ip6_hdr *ip6, const struct tcphdr *tp, u_int len) { return nextproto6_cksum(ndo, ip6, (const uint8_t *)tp, len, len, IPPROTO_TCP); } UNALIGNED_OK void tcp_print(netdissect_options *ndo, const u_char *bp, u_int length, const u_char *bp2, int fragmented) { const struct tcphdr *tp; const struct ip *ip; u_char flags; u_int hlen; char ch; uint16_t sport, dport, win, urp; uint32_t seq, ack, thseq, thack; u_int utoval; uint16_t magic; int rev; const struct ip6_hdr *ip6; u_int header_len; /* Header length in bytes */ ndo->ndo_protocol = "tcp"; tp = (const struct tcphdr *)bp; ip = (const struct ip *)bp2; if (IP_V(ip) == 6) ip6 = (const struct ip6_hdr *)bp2; else ip6 = NULL; ch = '\0'; if (!ND_TTEST_2(tp->th_dport)) { if (ip6) { ND_PRINT("%s > %s:", GET_IP6ADDR_STRING(ip6->ip6_src), GET_IP6ADDR_STRING(ip6->ip6_dst)); } else { ND_PRINT("%s > %s:", GET_IPADDR_STRING(ip->ip_src), GET_IPADDR_STRING(ip->ip_dst)); } nd_print_trunc(ndo); return; } sport = GET_BE_U_2(tp->th_sport); dport = GET_BE_U_2(tp->th_dport); if (ip6) { if (GET_U_1(ip6->ip6_nxt) == IPPROTO_TCP) { ND_PRINT("%s.%s > %s.%s: ", GET_IP6ADDR_STRING(ip6->ip6_src), tcpport_string(ndo, sport), GET_IP6ADDR_STRING(ip6->ip6_dst), tcpport_string(ndo, dport)); } else { ND_PRINT("%s > %s: ", tcpport_string(ndo, sport), tcpport_string(ndo, dport)); } } else { if (GET_U_1(ip->ip_p) == IPPROTO_TCP) { ND_PRINT("%s.%s > %s.%s: ", GET_IPADDR_STRING(ip->ip_src), tcpport_string(ndo, sport), GET_IPADDR_STRING(ip->ip_dst), tcpport_string(ndo, dport)); } else { ND_PRINT("%s > %s: ", tcpport_string(ndo, sport), tcpport_string(ndo, dport)); } } ND_TCHECK_SIZE(tp); hlen = TH_OFF(tp) * 4; if (hlen < sizeof(*tp)) { ND_PRINT(" tcp %u [bad hdr length %u - too short, < %zu]", length - hlen, hlen, sizeof(*tp)); return; } seq = GET_BE_U_4(tp->th_seq); ack = GET_BE_U_4(tp->th_ack); win = GET_BE_U_2(tp->th_win); urp = GET_BE_U_2(tp->th_urp); if (ndo->ndo_qflag) { ND_PRINT("tcp %u", length - hlen); if (hlen > length) { ND_PRINT(" [bad hdr length %u - too long, > %u]", hlen, length); } return; } flags = GET_U_1(tp->th_flags); ND_PRINT("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags)); if (!ndo->ndo_Sflag && (flags & TH_ACK)) { /* * 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). */ rev = 0; if (ip6) { struct tcp_seq_hash6 *th; struct tcp_seq_hash6 *tcp_seq_hash; const void *src, *dst; struct tha6 tha; tcp_seq_hash = tcp_seq_hash6; src = (const void *)ip6->ip6_src; dst = (const void *)ip6->ip6_dst; if (sport > dport) rev = 1; else if (sport == dport) { if (UNALIGNED_MEMCMP(src, dst, sizeof(ip6->ip6_dst)) > 0) rev = 1; } if (rev) { UNALIGNED_MEMCPY(&tha.src, dst, sizeof(ip6->ip6_dst)); UNALIGNED_MEMCPY(&tha.dst, src, sizeof(ip6->ip6_src)); tha.port = ((u_int)dport) << 16 | sport; } else { UNALIGNED_MEMCPY(&tha.dst, dst, sizeof(ip6->ip6_dst)); UNALIGNED_MEMCPY(&tha.src, src, sizeof(ip6->ip6_src)); tha.port = ((u_int)sport) << 16 | dport; } 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 */ /* calloc() return used by the 'tcp_seq_hash6' hash table: do not free() */ if (th->nxt == NULL) { th->nxt = (struct tcp_seq_hash6 *) calloc(1, sizeof(*th)); if (th->nxt == NULL) (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC, "%s: calloc", __func__); } 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 { struct tcp_seq_hash *th; struct tcp_seq_hash *tcp_seq_hash; struct tha tha; tcp_seq_hash = tcp_seq_hash4; if (sport > dport) rev = 1; else if (sport == dport) { if (UNALIGNED_MEMCMP(ip->ip_src, ip->ip_dst, sizeof(ip->ip_dst)) > 0) rev = 1; } if (rev) { UNALIGNED_MEMCPY(&tha.src, ip->ip_dst, sizeof(ip->ip_dst)); UNALIGNED_MEMCPY(&tha.dst, ip->ip_src, sizeof(ip->ip_src)); tha.port = ((u_int)dport) << 16 | sport; } else { UNALIGNED_MEMCPY(&tha.dst, ip->ip_dst, sizeof(ip->ip_dst)); UNALIGNED_MEMCPY(&tha.src, ip->ip_src, sizeof(ip->ip_src)); tha.port = ((u_int)sport) << 16 | dport; } 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 */ /* calloc() return used by the 'tcp_seq_hash4' hash table: do not free() */ if (th->nxt == NULL) { th->nxt = (struct tcp_seq_hash *) calloc(1, sizeof(*th)); if (th->nxt == NULL) (*ndo->ndo_error)(ndo, S_ERR_ND_MEM_ALLOC, "%s: calloc", __func__); } 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 = rev = 0; } if (hlen > length) { ND_PRINT(" [bad hdr length %u - too long, > %u]", hlen, length); return; } if (ndo->ndo_vflag && !ndo->ndo_Kflag && !fragmented) { /* Check the checksum, if possible. */ uint16_t sum, tcp_sum; if (IP_V(ip) == 4) { if (ND_TTEST_LEN(tp->th_sport, length)) { sum = tcp_cksum(ndo, ip, tp, length); tcp_sum = GET_BE_U_2(tp->th_sum); ND_PRINT(", cksum 0x%04x", tcp_sum); if (sum != 0) ND_PRINT(" (incorrect -> 0x%04x)", in_cksum_shouldbe(tcp_sum, sum)); else ND_PRINT(" (correct)"); } } else if (IP_V(ip) == 6) { if (ND_TTEST_LEN(tp->th_sport, length)) { sum = tcp6_cksum(ndo, ip6, tp, length); tcp_sum = GET_BE_U_2(tp->th_sum); ND_PRINT(", cksum 0x%04x", tcp_sum); if (sum != 0) ND_PRINT(" (incorrect -> 0x%04x)", in_cksum_shouldbe(tcp_sum, sum)); else ND_PRINT(" (correct)"); } } } length -= hlen; if (ndo->ndo_vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) { ND_PRINT(", seq %u", seq); if (length > 0) { ND_PRINT(":%u", seq + length); } } if (flags & TH_ACK) { ND_PRINT(", ack %u", ack); } ND_PRINT(", win %u", win); if (flags & TH_URG) ND_PRINT(", urg %u", urp); /* * Handle any options. */ if (hlen > sizeof(*tp)) { const u_char *cp; u_int i, opt, datalen; u_int len; hlen -= sizeof(*tp); cp = (const u_char *)tp + sizeof(*tp); ND_PRINT(", options ["); while (hlen > 0) { if (ch != '\0') ND_PRINT("%c", ch); opt = GET_U_1(cp); cp++; if (ZEROLENOPT(opt)) len = 1; else { len = GET_U_1(cp); 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; ND_TCHECK_LEN(cp, l); } ND_PRINT("%s", tok2str(tcp_option_values, "unknown-%u", opt)); switch (opt) { case TCPOPT_MAXSEG: datalen = 2; LENCHECK(datalen); ND_PRINT(" %u", GET_BE_U_2(cp)); break; case TCPOPT_WSCALE: datalen = 1; LENCHECK(datalen); ND_PRINT(" %u", GET_U_1(cp)); break; case TCPOPT_SACK: datalen = len - 2; if (datalen % 8 != 0) { ND_PRINT(" invalid sack"); } else { uint32_t s, e; ND_PRINT(" %u ", datalen / 8); for (i = 0; i < datalen; i += 8) { LENCHECK(i + 4); s = GET_BE_U_4(cp + i); LENCHECK(i + 8); e = GET_BE_U_4(cp + i + 4); if (rev) { s -= thseq; e -= thseq; } else { s -= thack; e -= thack; } ND_PRINT("{%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); ND_PRINT(" %u", GET_BE_U_4(cp)); break; case TCPOPT_TIMESTAMP: datalen = 8; LENCHECK(datalen); ND_PRINT(" val %u ecr %u", GET_BE_U_4(cp), GET_BE_U_4(cp + 4)); break; case TCPOPT_SIGNATURE: datalen = TCP_SIGLEN; LENCHECK(datalen); ND_PRINT(" "); #ifdef HAVE_LIBCRYPTO switch (tcp_verify_signature(ndo, ip, tp, bp + TH_OFF(tp) * 4, length, cp)) { case SIGNATURE_VALID: ND_PRINT("valid"); break; case SIGNATURE_INVALID: nd_print_invalid(ndo); break; case CANT_CHECK_SIGNATURE: ND_PRINT("can't check - "); for (i = 0; i < TCP_SIGLEN; ++i) ND_PRINT("%02x", GET_U_1(cp + i)); break; } #else for (i = 0; i < TCP_SIGLEN; ++i) ND_PRINT("%02x", GET_U_1(cp + i)); #endif break; case TCPOPT_SCPS: datalen = 2; LENCHECK(datalen); ND_PRINT(" cap %02x id %u", GET_U_1(cp), GET_U_1(cp + 1)); break; case TCPOPT_TCPAO: datalen = len - 2; /* RFC 5925 Section 2.2: * "The Length value MUST be greater than or equal to 4." * (This includes the Kind and Length fields already processed * at this point.) */ if (datalen < 2) { nd_print_invalid(ndo); } else { LENCHECK(1); ND_PRINT(" keyid %u", GET_U_1(cp)); LENCHECK(2); ND_PRINT(" rnextkeyid %u", GET_U_1(cp + 1)); if (datalen > 2) { ND_PRINT(" mac 0x"); for (i = 2; i < datalen; i++) { LENCHECK(i + 1); ND_PRINT("%02x", GET_U_1(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 = GET_BE_U_2(cp); ND_PRINT(" 0x%x", utoval); if (utoval & 0x0001) utoval = (utoval >> 1) * 60; else utoval >>= 1; ND_PRINT(" %u", utoval); break; case TCPOPT_MPTCP: { const u_char *snapend_save; int ret; datalen = len - 2; LENCHECK(datalen); /* Update the snapend to the end of the option * before calling mptcp_print(). Some options * (MPTCP or others) may be present after a * MPTCP option. This prevents that, in * mptcp_print(), the remaining length < the * remaining caplen. */ snapend_save = ndo->ndo_snapend; ndo->ndo_snapend = ND_MIN(cp - 2 + len, ndo->ndo_snapend); ret = mptcp_print(ndo, cp - 2, len, flags); ndo->ndo_snapend = snapend_save; if (!ret) goto bad; break; } case TCPOPT_FASTOPEN: datalen = len - 2; LENCHECK(datalen); ND_PRINT(" "); print_tcp_fastopen_option(ndo, cp, datalen, FALSE); break; case TCPOPT_EXPERIMENT2: datalen = len - 2; LENCHECK(datalen); if (datalen < 2) goto bad; /* RFC6994 */ magic = GET_BE_U_2(cp); ND_PRINT("-"); switch(magic) { case 0xf989: /* TCP Fast Open RFC 7413 */ print_tcp_fastopen_option(ndo, cp + 2, datalen - 2, TRUE); break; default: /* Unknown magic number */ ND_PRINT("%04x", magic); break; } break; default: datalen = len - 2; if (datalen) ND_PRINT(" 0x"); for (i = 0; i < datalen; ++i) { LENCHECK(i + 1); ND_PRINT("%02x", GET_U_1(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) ND_PRINT("[len %u]", len); ch = ','; if (opt == TCPOPT_EOL) break; } ND_PRINT("]"); } /* * Print length field before crawling down the stack. */ ND_PRINT(", length %u", length); if (length == 0) return; /* * Decode payload if necessary. */ header_len = TH_OFF(tp) * 4; /* * Do a bounds check before decoding the payload. * At least the header data is required. */ if (!ND_TTEST_LEN(bp, header_len)) { ND_PRINT(" [remaining caplen(%u) < header length(%u)]", ND_BYTES_AVAILABLE_AFTER(bp), header_len); nd_trunc_longjmp(ndo); } bp += header_len; if ((flags & TH_RST) && ndo->ndo_vflag) { print_tcp_rst_data(ndo, bp, length); return; } if (ndo->ndo_packettype) { switch (ndo->ndo_packettype) { case PT_ZMTP1: zmtp1_print(ndo, bp, length); break; case PT_RESP: resp_print(ndo, bp, length); break; case PT_DOMAIN: /* over_tcp: TRUE, is_mdns: FALSE */ domain_print(ndo, bp, length, TRUE, FALSE); break; } return; } if (IS_SRC_OR_DST_PORT(FTP_PORT)) { ND_PRINT(": "); ftp_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(SSH_PORT)) { ssh_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(TELNET_PORT)) { telnet_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(SMTP_PORT)) { ND_PRINT(": "); smtp_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(WHOIS_PORT)) { ND_PRINT(": "); whois_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(NAMESERVER_PORT)) { /* over_tcp: TRUE, is_mdns: FALSE */ domain_print(ndo, bp, length, TRUE, FALSE); } else if (IS_SRC_OR_DST_PORT(HTTP_PORT)) { ND_PRINT(": "); http_print(ndo, bp, length); #ifdef ENABLE_SMB } else if (IS_SRC_OR_DST_PORT(NETBIOS_SSN_PORT)) { nbt_tcp_print(ndo, bp, length); #endif } else if (IS_SRC_OR_DST_PORT(BGP_PORT)) { bgp_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(RPKI_RTR_PORT)) { rpki_rtr_print(ndo, bp, length); #ifdef ENABLE_SMB } else if (IS_SRC_OR_DST_PORT(SMB_PORT)) { smb_tcp_print(ndo, bp, length); #endif } else if (IS_SRC_OR_DST_PORT(RTSP_PORT)) { ND_PRINT(": "); rtsp_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(MSDP_PORT)) { msdp_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(LDP_PORT)) { ldp_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(PPTP_PORT)) pptp_print(ndo, bp); else if (IS_SRC_OR_DST_PORT(REDIS_PORT)) resp_print(ndo, bp, length); else if (IS_SRC_OR_DST_PORT(BEEP_PORT)) beep_print(ndo, bp, length); else if (IS_SRC_OR_DST_PORT(OPENFLOW_PORT_OLD) || IS_SRC_OR_DST_PORT(OPENFLOW_PORT_IANA)) { openflow_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(HTTP_PORT_ALT)) { ND_PRINT(": "); http_print(ndo, bp, length); } else if (IS_SRC_OR_DST_PORT(RTSP_PORT_ALT)) { ND_PRINT(": "); rtsp_print(ndo, bp, length); } else if ((IS_SRC_OR_DST_PORT(NFS_PORT)) && length >= 4 && ND_TTEST_4(bp)) { /* * 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. */ uint32_t fraglen; const struct sunrpc_msg *rp; enum sunrpc_msg_type direction; fraglen = GET_BE_U_4(bp) & 0x7FFFFFFF; if (fraglen > (length) - 4) fraglen = (length) - 4; rp = (const struct sunrpc_msg *)(bp + 4); if (ND_TTEST_4(rp->rm_direction)) { direction = (enum sunrpc_msg_type) GET_BE_U_4(rp->rm_direction); if (dport == NFS_PORT && direction == SUNRPC_CALL) { ND_PRINT(": NFS request xid %u ", GET_BE_U_4(rp->rm_xid)); nfsreq_noaddr_print(ndo, (const u_char *)rp, fraglen, (const u_char *)ip); return; } if (sport == NFS_PORT && direction == SUNRPC_REPLY) { ND_PRINT(": NFS reply xid %u ", GET_BE_U_4(rp->rm_xid)); nfsreply_noaddr_print(ndo, (const u_char *)rp, fraglen, (const u_char *)ip); return; } } } return; bad: ND_PRINT("[bad opt]"); if (ch != '\0') ND_PRINT("]"); return; trunc: nd_print_trunc(ndo); if (ch != '\0') ND_PRINT(">"); } /* * 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(netdissect_options *ndo, const u_char *sp, u_int length) { u_char c; ND_PRINT(ND_TTEST_LEN(sp, length) ? " [RST" : " [!RST"); if (length > MAX_RST_DATA_LEN) { length = MAX_RST_DATA_LEN; /* can use -X for longer */ ND_PRINT("+"); /* indicate we truncate */ } ND_PRINT(" "); while (length && sp < ndo->ndo_snapend) { c = GET_U_1(sp); sp++; fn_print_char(ndo, c); length--; } ND_PRINT("]"); } static void print_tcp_fastopen_option(netdissect_options *ndo, const u_char *cp, u_int datalen, int exp) { u_int i; if (exp) ND_PRINT("tfo"); if (datalen == 0) { /* Fast Open Cookie Request */ ND_PRINT(" cookiereq"); } else { /* Fast Open Cookie */ if (datalen % 2 != 0 || datalen < 4 || datalen > 16) { nd_print_invalid(ndo); } else { ND_PRINT(" cookie "); for (i = 0; i < datalen; ++i) ND_PRINT("%02x", GET_U_1(cp + i)); } } } #ifdef HAVE_LIBCRYPTO DIAG_OFF_DEPRECATION static int tcp_verify_signature(netdissect_options *ndo, const struct ip *ip, const struct tcphdr *tp, const u_char *data, u_int length, const u_char *rcvsig) { struct tcphdr tp1; u_char sig[TCP_SIGLEN]; char zero_proto = 0; MD5_CTX ctx; uint16_t savecsum, tlen; const struct ip6_hdr *ip6; uint32_t len32; uint8_t nxt; if (data + length > ndo->ndo_snapend) { ND_PRINT("snaplen too short, "); return (CANT_CHECK_SIGNATURE); } tp1 = *tp; if (ndo->ndo_sigsecret == NULL) { ND_PRINT("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, (const char *)&ip->ip_src, sizeof(ip->ip_src)); MD5_Update(&ctx, (const char *)&ip->ip_dst, sizeof(ip->ip_dst)); MD5_Update(&ctx, (const char *)&zero_proto, sizeof(zero_proto)); MD5_Update(&ctx, (const char *)&ip->ip_p, sizeof(ip->ip_p)); tlen = GET_BE_U_2(ip->ip_len) - IP_HL(ip) * 4; tlen = htons(tlen); MD5_Update(&ctx, (const char *)&tlen, sizeof(tlen)); } else if (IP_V(ip) == 6) { ip6 = (const struct ip6_hdr *)ip; MD5_Update(&ctx, (const char *)&ip6->ip6_src, sizeof(ip6->ip6_src)); MD5_Update(&ctx, (const char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst)); len32 = htonl(GET_BE_U_2(ip6->ip6_plen)); MD5_Update(&ctx, (const char *)&len32, sizeof(len32)); nxt = 0; MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt)); MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt)); MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt)); nxt = IPPROTO_TCP; MD5_Update(&ctx, (const char *)&nxt, sizeof(nxt)); } else { ND_PRINT("IP version not 4 or 6, "); return (CANT_CHECK_SIGNATURE); } /* * Step 2: Update MD5 hash with TCP header, excluding options. * The TCP checksum must be set to zero. */ memcpy(&savecsum, tp1.th_sum, sizeof(savecsum)); memset(tp1.th_sum, 0, sizeof(tp1.th_sum)); MD5_Update(&ctx, (const char *)&tp1, sizeof(struct tcphdr)); memcpy(tp1.th_sum, &savecsum, sizeof(tp1.th_sum)); /* * 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, ndo->ndo_sigsecret, strlen(ndo->ndo_sigsecret)); MD5_Final(sig, &ctx); if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0) return (SIGNATURE_VALID); else return (SIGNATURE_INVALID); } DIAG_ON_DEPRECATION #endif /* HAVE_LIBCRYPTO */