Use nextproto6_cksum() for XXX-over-IPv6 checksums.

Get rid of duplicated checksums with IPv6 pseudo-headers.

Author: guyharris

ip6.h

@@ -187,6 +187,6 @@ struct ip6_frag {
 #define IP6F_MORE_FRAG		0x0001	/* more-fragments flag */
 
 /* in print-ip6.c */
-extern int nextproto6_cksum(const struct ip6_hdr *, const u_short *, u_int, u_int);
+extern int nextproto6_cksum(const struct ip6_hdr *, const u_int8_t *, u_int, u_int);
 
 #endif /* not _NETINET_IP6_H_ */

netdissect.h

@@ -461,7 +461,7 @@ extern u_int ieee802_15_4_if_print(netdissect_options *,const struct pcap_pkthdr
 extern void ip6_print(netdissect_options *,const u_char *, u_int);
 #if 0
 extern void ip6_opt_print(netdissect_options *,const u_char *, int);
-extern int nextproto6_cksum(const struct ip6_hdr *, const u_short *, u_int, u_int);
+extern int nextproto6_cksum(const struct ip6_hdr *, const u_int8_t *, u_int, u_int);
 extern int hbhopt_print(netdissect_options *,const u_char *);
 extern int dstopt_print(netdissect_options *,const u_char *);
 extern int frag6_print(netdissect_options *,const u_char *,

print-dccp.c

@@ -103,28 +103,8 @@ static int dccp_cksum(const struct ip *ip,
 #ifdef INET6
 static int dccp6_cksum(const struct ip6_hdr *ip6, const struct dccp_hdr *dh, u_int len)
 {
-	int cov = dccp_csum_coverage(dh, len);
-	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;
-	struct cksum_vec vec[2];
-
-	/* pseudo-header */
-	memset(&ph, 0, sizeof(ph));
-	ph.ph_src = ip6->ip6_src;
-	ph.ph_dst = ip6->ip6_dst;
-	ph.ph_len = htonl(len);
-	ph.ph_nxt = IPPROTO_DCCP;
-
-	vec[0].ptr = (const u_int8_t *)(void *)&ph;
-	vec[0].len = sizeof(ph);
-	vec[1].ptr = (const u_int8_t *)(void *)dh;
-	vec[1].len = cov;
-	return in_cksum(vec, 2);
+	return nextproto6_cksum(ip6, (const u_int8_t *)(void *)dh,
+	    dccp_csum_coverage(dh, len), IPPROTO_DCCP);
 }
 #endif
 

print-icmp6.c

@@ -197,44 +197,8 @@ print_lladdr(const u_int8_t *p, size_t l)
 static int icmp6_cksum(const struct ip6_hdr *ip6, const struct icmp6_hdr *icp,
 	u_int len)
 {
-	size_t i;
-	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;
-
-	/* 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_ICMPV6;
-
-	sum = 0;
-	for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
-		sum += phu.pa[i];
-
-	sp = (const u_int16_t *)icp;
-
-	for (i = 0; i < (len & ~1); i += 2)
-		sum += *sp++;
-
-	if (len & 1)
-		sum += htons((*(const u_int8_t *)sp) << 8);
-
-	while (sum > 0xffff)
-		sum = (sum & 0xffff) + (sum >> 16);
-	sum = ~sum & 0xffff;
-
-	return (sum);
+	return (nextproto6_cksum(ip6, (const u_int8_t *)(void *)icp, len,
+	    IPPROTO_ICMPV6));
 }
 
 enum ND_RPL_CODE {

print-ip6.c

@@ -48,7 +48,7 @@ static const char rcsid[] _U_ =
  * Compute a V6-style checksum by building a pseudoheader.
  */
 int
-nextproto6_cksum(const struct ip6_hdr *ip6, const u_short *data,
+nextproto6_cksum(const struct ip6_hdr *ip6, const u_int8_t *data,
 		 u_int len, u_int next_proto)
 {
         struct {
@@ -69,7 +69,7 @@ nextproto6_cksum(const struct ip6_hdr *ip6, const u_short *data,
 
         vec[0].ptr = (const u_int8_t *)(void *)&ph;
         vec[0].len = sizeof(ph);
-        vec[1].ptr = (const u_int8_t *)(void *)data;
+        vec[1].ptr = data;
         vec[1].len = len;
 
         return in_cksum(vec, 2);
@@ -225,7 +225,7 @@ ip6_print(netdissect_options *ndo, const u_char *bp, u_int length)
 		    }
 
 		case IPPROTO_PIM:
-			pim_print(cp, len, nextproto6_cksum(ip6, (u_short *)cp, len,
+			pim_print(cp, len, nextproto6_cksum(ip6, cp, len,
 							    IPPROTO_PIM));
 			return;
 

print-tcp.c

@@ -432,7 +432,7 @@ tcp_print(register const u_char *bp, register u_int length,
 #ifdef INET6
                 else if (IP_V(ip) == 6 && ip6->ip6_plen) {
                         if (TTEST2(tp->th_sport, length)) {
-                                sum = nextproto6_cksum(ip6, (u_short *)tp, length, IPPROTO_TCP);
+                                sum = nextproto6_cksum(ip6, (const u_int8_t *)tp, length, IPPROTO_TCP);
                                 tcp_sum = EXTRACT_16BITS(&tp->th_sum);
 
                                 (void)printf(", cksum 0x%04x", tcp_sum);

print-udp.c

@@ -316,27 +316,8 @@ static int udp_cksum(register const struct ip *ip,
 static int udp6_cksum(const struct ip6_hdr *ip6, const struct udphdr *up,
 	u_int len)
 {
-	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;
-	struct cksum_vec vec[2];
-
-	/* pseudo-header */
-	memset(&ph, 0, sizeof(ph));
-	ph.ph_src = ip6->ip6_src;
-	ph.ph_dst = ip6->ip6_dst;
-	ph.ph_len = htonl(len);
-	ph.ph_nxt = IPPROTO_UDP;
-
-	vec[0].ptr = (const u_int8_t *)(void *)&ph;
-	vec[0].len = sizeof(ph);
-	vec[1].ptr = (const u_int8_t *)(void *)up;
-	vec[1].len = len;
-	return (in_cksum(vec, 2));
+	return (nextproto6_cksum(ip6, (const u_int8_t *)(void *)up, len,
+	    IPPROTO_UDP));
 }
 #endif