X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/52d93585482b1698092955019032becbe97a9df9..cb4e517e9aae83b3bc0beac4ad9fb9f2318a4dd2:/print-tcp.c diff --git a/print-tcp.c b/print-tcp.c index fe8f5eab..0f684272 100644 --- a/print-tcp.c +++ b/print-tcp.c @@ -21,7 +21,7 @@ #ifndef lint static const char rcsid[] = - "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.66 2000-06-01 01:09:32 assar Exp $ (LBL)"; + "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.72 2000-08-01 17:35:05 itojun Exp $ (LBL)"; #endif #ifdef HAVE_CONFIG_H @@ -39,12 +39,10 @@ static const char rcsid[] = #include #include -#ifdef HAVE_MEMORY_H -#include -#endif #include #include #include +#include #include #ifdef INET6 @@ -55,6 +53,10 @@ static const char rcsid[] = #include "addrtoname.h" #include "extract.h" +static void print_tcp_rst_data(register const u_char *sp, u_int length); + +#define MAX_RST_DATA_LEN 30 + /* Compatibility */ #ifndef TCPOPT_WSCALE #define TCPOPT_WSCALE 3 /* window scale factor (rfc1072) */ @@ -132,6 +134,99 @@ static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE]; #define NFS_PORT 2049 #endif +static int tcp_cksum(register const struct ip *ip, + register const struct tcphdr *tp, + register int len) +{ + int i, tlen; + union phu { + struct phdr { + u_int32_t src; + u_int32_t dst; + u_char mbz; + u_char proto; + u_int16_t len; + } ph; + u_int16_t pa[6]; + } phu; + register const u_int16_t *sp; + u_int32_t sum; + tlen = ntohs(ip->ip_len) - ((const char *)tp-(const char*)ip); + + /* pseudo-header.. */ + phu.ph.len = htons(tlen); + phu.ph.mbz = 0; + phu.ph.proto = IPPROTO_TCP; + memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t)); + memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t)); + + sp = &phu.pa[0]; + sum = sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]; + + sp = (const u_int16_t *)tp; + + for (i=0; i<(tlen&~1); i+= 2) + sum += *sp++; + + if (tlen & 1) { + sum += htons( (*(const char *)sp) << 8); + } + + while (sum > 0xffff) + sum = (sum & 0xffff) + (sum >> 16); + sum = ~sum & 0xffff; + + return (sum); +} + +#ifdef INET6 +static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp, + int len) +{ + int i, tlen; + register const u_int16_t *sp; + u_int32_t sum; + union { + struct { + struct in6_addr ph_src; + struct in6_addr ph_dst; + u_int32_t ph_len; + u_int8_t ph_zero[3]; + u_int8_t ph_nxt; + } ph; + u_int16_t pa[20]; + } phu; + + tlen = ntohs(ip6->ip6_plen) + sizeof(struct ip6_hdr) - + ((const char *)tp - (const char*)ip6); + + /* pseudo-header */ + memset(&phu, 0, sizeof(phu)); + phu.ph.ph_src = ip6->ip6_src; + phu.ph.ph_dst = ip6->ip6_dst; + phu.ph.ph_len = htonl(tlen); + phu.ph.ph_nxt = IPPROTO_TCP; + + sum = 0; + for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++) + sum += phu.pa[i]; + + sp = (const u_int16_t *)tp; + + for (i = 0; i < (tlen & ~1); i += 2) + sum += *sp++; + + if (tlen & 1) + sum += htons((*(const char *)sp) << 8); + + while (sum > 0xffff) + sum = (sum & 0xffff) + (sum >> 16); + sum = ~sum & 0xffff; + + return (sum); +} +#endif + void tcp_print(register const u_char *bp, register u_int length, register const u_char *bp2) @@ -255,7 +350,7 @@ tcp_print(register const u_char *bp, register u_int length, * both directions). */ #ifdef INET6 - bzero(&tha, sizeof(tha)); + memset(&tha, 0, sizeof(tha)); rev = 0; if (ip6) { if (sport > dport) { @@ -348,6 +443,30 @@ tcp_print(register const u_char *bp, register u_int length, (void)printf(" [bad hdr length]"); return; } + + if (ip->ip_v == 4 && vflag) { + int sum; + if (TTEST2(tp->th_sport, length)) { + sum = tcp_cksum(ip, tp, length); + if (sum != 0) + (void)printf(" [bad tcp cksum %x!]", sum); + else + (void)printf(" [tcp sum ok]"); + } + } +#ifdef INET6 + if (ip->ip_v == 6 && ip6->ip6_plen && vflag) { + int sum; + if (TTEST2(tp->th_sport, length)) { + sum = tcp6_cksum(ip6, tp, length); + if (sum != 0) + (void)printf(" [bad tcp cksum %x!]", sum); + else + (void)printf(" [tcp sum ok]"); + } + } +#endif + length -= hlen; if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) (void)printf(" %u:%u(%d)", seq, seq + length, length); @@ -521,13 +640,18 @@ tcp_print(register const u_char *bp, register u_int length, * Decode payload if necessary. */ bp += (tp->th_off * 4); - if (!qflag && vflag && length > 0 - && (sport == TELNET_PORT || dport == TELNET_PORT)) - telnet_print(bp, length); - else if (sport == BGP_PORT || dport == BGP_PORT) - bgp_print(bp, length); - else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT) - nbt_tcp_print(bp, length); + if (flags & TH_RST) { + if (vflag) + print_tcp_rst_data(bp, length); + } else { + 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 == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT) + nbt_tcp_print(bp, length); + } return; bad: fputs("[bad opt]", stdout); @@ -540,3 +664,41 @@ trunc: 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++; + if (isprint(c)) + putchar(c); + else + putchar('.'); + } + putchar(']'); +}