udp header checksum. from netbsd.

[tcpdump] / print-tcp.c

diff --git a/print-tcp.c b/print-tcp.c
index 8afd8a1a535fcb28076861a4ae64a18e81f58f04..0f684272f8acc676e62261ac4562d3d593830e97 100644 (file)
--- 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 1.70 2000-07-30 05:56:11 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
@@ -134,6 +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)
@@ -350,6 +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);