udp header checksum. from netbsd.

diff --git a/print-udp.c b/print-udp.c
index ef0266c34609638edde80f0b2035a4b7416e6d95..11f60838f69b50b055da40ae003b30e3af77ed30 100644 (file)
--- a/print-udp.c
+++ b/print-udp.c
@@ -21,7 +21,7 @@
 
 #ifndef lint
 static const char rcsid[] =
-    "@(#) $Header: /tcpdump/master/tcpdump/print-udp.c,v 1.75 2000-07-22 23:58:01 assar Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/tcpdump/print-udp.c,v 1.76 2000-08-01 17:36:49 itojun Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -292,6 +292,100 @@ rtcp_print(const u_char *hdr, const u_char *ep)
        return (hdr + len);
 }
 
+static int udp_cksum(register const struct ip *ip,
+                    register const struct udphdr *up,
+                    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 *)up-(const char*)ip);
+
+       /* pseudo-header.. */
+       phu.ph.len = htons(tlen);
+       phu.ph.mbz = 0;
+       phu.ph.proto = IPPROTO_UDP;
+       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 *)up;
+
+       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 udp6_cksum(const struct ip6_hdr *ip6, const struct udphdr *up,
+       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 *)up - (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_UDP;
+
+       sum = 0;
+       for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
+               sum += phu.pa[i];
+
+       sp = (const u_int16_t *)up;
+
+       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
+
+
 /* XXX probably should use getservbyname() and cache answers */
 #define TFTP_PORT 69           /*XXX*/
 #define KERBEROS_PORT 88       /*XXX*/
@@ -504,6 +598,32 @@ udp_print(register const u_char *bp, u_int length, register const u_char *bp2)
        }
 #endif
 
+       if (ip->ip_v == 4 && vflag) {
+               int sum = up->uh_sum;
+               if (sum == 0) {
+                       (void)printf(" [no cksum]");
+               } else if (TTEST2(cp[0], length)) {
+                       sum = udp_cksum(ip, up, length);
+                       if (sum != 0)
+                               (void)printf(" [bad udp cksum %x!]", sum);
+                       else
+                               (void)printf(" [udp sum ok]");
+               }
+       }
+#ifdef INET6
+       if (ip->ip_v == 6 && ip6->ip6_plen && vflag) {
+               int sum = up->uh_sum;
+               /* for IPv6, UDP checksum is mandatory */
+               if (TTEST2(cp[0], length)) {
+                       sum = udp6_cksum(ip6, up, length);
+                       if (sum != 0)
+                               (void)printf(" [bad udp cksum %x!]", sum);
+                       else
+                               (void)printf(" [udp sum ok]");
+               }
+       }
+#endif
+
        if (!qflag) {
 #define ISPORT(p) (dport == (p) || sport == (p))
                if (ISPORT(NAMESERVER_PORT))