X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/a6f81d534ddc1026442664d21a2122d64ab571a9..a890c4489fa1bcee9f455ee28d772bb1ccf590bf:/print-pim.c

diff --git a/print-pim.c b/print-pim.c
index 15f4c513..788af214 100644
--- a/print-pim.c
+++ b/print-pim.c
@@ -31,6 +31,7 @@
 #include "extract.h"
 
 #include "ip.h"
+#include "ip6.h"
 
 #define PIMV1_TYPE_QUERY           0
 #define PIMV1_TYPE_REGISTER        1
@@ -134,7 +135,7 @@ struct pim {
 	u_short	pim_cksum;	/* IP style check sum */
 };
 
-static void pimv2_print(netdissect_options *, register const u_char *bp, register u_int len, u_int cksum);
+static void pimv2_print(netdissect_options *, register const u_char *bp, register u_int len, const u_char *);
 
 static void
 pimv1_join_prune_print(netdissect_options *ndo,
@@ -415,7 +416,7 @@ trunc:
 
 void
 pim_print(netdissect_options *ndo,
-          register const u_char *bp, register u_int len, u_int cksum)
+          register const u_char *bp, register u_int len, const u_char *bp2)
 {
 	register const u_char *ep;
 	register struct pim *pim = (struct pim *)bp;
@@ -440,7 +441,7 @@ pim_print(netdissect_options *ndo,
 			          PIM_VER(pim->pim_typever),
 			          len,
 			          tok2str(pimv2_type_values,"Unknown Type",PIM_TYPE(pim->pim_typever))));
-			pimv2_print(ndo, bp, len, cksum);
+			pimv2_print(ndo, bp, len, bp2);
 		}
 		break;
 	default:
@@ -620,13 +621,47 @@ trunc:
 	return -1;
 }
 
+enum checksum_status {
+	CORRECT,
+	INCORRECT,
+	UNVERIFIED
+};
+
+static enum checksum_status
+pimv2_check_checksum(const u_char *bp, const u_char *bp2, u_int len)
+{
+	const struct ip *ip;
+	u_int cksum;
+
+	ip = (const struct ip *)bp2;
+	if (IP_V(ip) == 4) {
+		struct cksum_vec vec[1];
+
+		vec[0].ptr = bp;
+		vec[0].len = len;
+		cksum = in_cksum(vec, 1);
+		return (cksum ? INCORRECT : CORRECT);
+#ifdef INET6
+	} else if (IP_V(ip) == 6) {
+		const struct ip6_hdr *ip6;
+
+		ip6 = (const struct ip6_hdr *)bp2;
+		cksum = nextproto6_cksum(ip6, bp, len, len, IPPROTO_PIM);
+		return (cksum ? INCORRECT : CORRECT);
+#endif
+	} else {
+		return (UNVERIFIED);
+	}
+}
+
 static void
 pimv2_print(netdissect_options *ndo,
-            register const u_char *bp, register u_int len, u_int cksum)
+            register const u_char *bp, register u_int len, const u_char *bp2)
 {
 	register const u_char *ep;
 	register struct pim *pim = (struct pim *)bp;
 	int advance;
+	enum checksum_status cksum_status;
 
 	ep = (const u_char *)ndo->ndo_snapend;
 	if (bp >= ep)
@@ -642,7 +677,41 @@ pimv2_print(netdissect_options *ndo,
 	if (EXTRACT_16BITS(&pim->pim_cksum) == 0) {
 		ND_PRINT((ndo, "(unverified)"));
 	} else {
-		ND_PRINT((ndo, "(%scorrect)", ND_TTEST2(bp[0], len) && cksum ? "in" : "" ));
+		if (PIM_TYPE(pim->pim_typever) == PIMV2_TYPE_REGISTER) {
+			/*
+			 * The checksum only covers the packet header,
+			 * not the encapsulated packet.
+			 */
+			cksum_status = pimv2_check_checksum(bp, bp2, 8);
+			if (cksum_status == INCORRECT) {
+				/*
+				 * To quote RFC 4601, "For interoperability
+				 * reasons, a message carrying a checksum
+				 * calculated over the entire PIM Register
+				 * message should also be accepted."
+				 */
+				cksum_status = pimv2_check_checksum(bp, bp2, len);
+			}
+		} else {
+			/*
+			 * The checksum covers the entire packet.
+			 */
+			cksum_status = pimv2_check_checksum(bp, bp2, len);
+		}
+		switch (cksum_status) {
+
+		case CORRECT:
+			ND_PRINT((ndo, "(correct)"));
+			break;
+
+		case INCORRECT:
+			ND_PRINT((ndo, "(incorrect)"));
+			break;
+
+		case UNVERIFIED:
+			ND_PRINT((ndo, "(unverified)"));
+			break;
+		}
 	}
 
 	switch (PIM_TYPE(pim->pim_typever)) {