Add TCP/UDP checksum display for v6 and clean up the checksum

calculation.  Mostly from tcpdump.org; ok jsing@

1 files changed, 45 insertions, 19 deletions

diff --git a/usr.sbin/tcpdump/print-tcp.c b/usr.sbin/tcpdump/print-tcp.c
index f393d1aff25..9b00d8244b2 100644
--- a/usr.sbin/tcpdump/print-tcp.c
+++ b/usr.sbin/tcpdump/print-tcp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: print-tcp.c,v 1.27 2009/10/27 23:59:56 deraadt Exp $	*/
+/*	$OpenBSD: print-tcp.c,v 1.28 2010/01/12 06:10:33 naddy Exp $	*/
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
@@ -126,11 +126,8 @@ static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
 #endif
 #define NETBIOS_SSN_PORT 139
 
-static int tcp_cksum(register const struct ip *ip,
-		     register const struct tcphdr *tp,
-		     register int len)
+static int tcp_cksum(const struct ip *ip, const struct tcphdr *tp, int len)
 {
-	int i, tlen;
 	union phu {
 		struct phdr {
 			u_int32_t src;
@@ -141,35 +138,52 @@ static int tcp_cksum(register const struct ip *ip,
 		} ph;
 		u_int16_t pa[6];
 	} phu;
-	register const u_int16_t *sp;
+	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.len = htons((u_int16_t)len);
 	phu.ph.mbz = 0;
-	phu.ph.proto = ip->ip_p;
+	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;
+	return in_cksum((u_short *)tp, len, sum);
+}
 
-	for (i=0; i<(tlen&~1); i+= 2)
-		sum += *sp++;
+#ifdef INET6
+static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
+		      u_int len)
+{
+	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;
+	size_t i;
+	u_int32_t sum = 0;
 
-	if (tlen & 1) {
-		sum += htons( (*(const char *)sp) << 8);
-	}
+	/* 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(len);
+	phu.ph.ph_nxt = IPPROTO_TCP;
 
-	while (sum > 0xffff)
-		sum = (sum & 0xffff) + (sum >> 16);
-	sum = ~sum & 0xffff;
+	for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
+		sum += phu.pa[i];
 
-	return (sum);
+	return in_cksum((u_short *)tp, len, sum);
 }
+#endif
 
 
 void
@@ -416,6 +430,18 @@ tcp_print(register const u_char *bp, register u_int length,
 				(void)printf(" [tcp sum ok]");
 		}
 	}
+#ifdef INET6
+	if (ip6 && 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
 
 	/* OS Fingerprint */
 	if (oflag && (flags & (TH_SYN|TH_ACK)) == TH_SYN) {