ping: suppress duplicate reply messages in context of multicast

Bug report asks to suppress duplicate messages when pinging multicast
address.  This commit does that, and allows one to re-enable duplicates with
verbose option.  After all ping is debugging tool, so there needs to be a
way to debug.

Addresses: https://github.com/iputils/iputils/issues/195
Bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=498429
Reported-by: Noah Meyerhans <noahm@debian.org>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>

5 files changed, 15 insertions, 8 deletions

diff --git a/doc/ping.xml b/doc/ping.xml
index f567523..75eadcf 100644
--- a/doc/ping.xml
+++ b/doc/ping.xml
@@ -643,7 +643,8 @@ xml:id="man.ping">
           <option>-v</option>
         </term>
         <listitem>
-          <para>Verbose output.</para>
+          <para>Verbose output. Do not suppress DUP replies when pinging
+          multicast address.</para>
         </listitem>
       </varlistentry>
       <varlistentry>
diff --git a/ping.c b/ping.c
index 3b3fa33..c4692e2 100644
--- a/ping.c
+++ b/ping.c
@@ -85,6 +85,7 @@ static int optlen = 0;
 static int settos = 0;			/* Set TOS, Precedence or other QOS options */
 
 static int broadcast_pings = 0;
+static int multicast;
 
 static void pr_options(unsigned char *cp, int hlen);
 static void pr_iph(struct iphdr *ip);
@@ -708,6 +709,7 @@ int ping4_run(int argc, char **argv, struct addrinfo *ai, socket_st *sock)
 	}
 
 	if (broadcast_pings || IN_MULTICAST(ntohl(whereto.sin_addr.s_addr))) {
+		multicast = 1;
 		if (uid) {
 			if (interval < 1000)
 				error(2, 0, _("broadcast ping with too short interval: %d"), interval);
@@ -1061,7 +1063,7 @@ ping4_parse_reply(struct socket_st *sock, struct msghdr *msg, int cc, void *addr
 		if (gather_statistics((uint8_t *)icp, sizeof(*icp), cc,
 				      ntohs(icp->un.echo.sequence),
 				      reply_ttl, 0, tv, pr_addr(from, sizeof *from),
-				      pr_echo_reply)) {
+				      pr_echo_reply, multicast)) {
 			fflush(stdout);
 			return 0;
 		}
diff --git a/ping.h b/ping.h
index 4195d4c..1d015ad 100644
--- a/ping.h
+++ b/ping.h
@@ -312,7 +312,7 @@ extern void common_options(int ch);
 extern int gather_statistics(uint8_t *ptr, int icmplen,
 			     int cc, uint16_t seq, int hops,
 			     int csfailed, struct timeval *tv, char *from,
-			     void (*pr_reply)(uint8_t *ptr, int cc));
+			     void (*pr_reply)(uint8_t *ptr, int cc), int multicast);
 extern void print_timestamp(void);
 void fill(char *patp, unsigned char *packet, unsigned packet_size);
 
diff --git a/ping6_common.c b/ping6_common.c
index 330b87a..4e083c1 100644
--- a/ping6_common.c
+++ b/ping6_common.c
@@ -78,6 +78,7 @@ uint32_t tclass;
 
 static struct sockaddr_in6 whereto;
 static struct sockaddr_in6 firsthop;
+static int multicast;
 
 static unsigned char cmsgbuf[4096];
 static size_t cmsglen = 0;
@@ -697,7 +698,8 @@ int ping6_run(int argc, char **argv, struct addrinfo *ai, struct socket_st *sock
 		ipi->ipi6_ifindex = if_name2index(device);
 	}
 
-	if ((whereto.sin6_addr.s6_addr16[0] & htons(0xff00)) == htons(0xff00)) {
+	if (IN6_IS_ADDR_MULTICAST(&whereto.sin6_addr)) {
+		multicast = 1;
 		if (uid) {
 			if (interval < 1000)
 				error(2, 0, _("multicast ping with too short interval: %d"), interval);
@@ -1209,7 +1211,8 @@ ping6_parse_reply(socket_st *sock, struct msghdr *msg, int cc, void *addr, struc
 		if (gather_statistics((uint8_t *)icmph, sizeof(*icmph), cc,
 				      ntohs(icmph->icmp6_seq),
 				      hops, 0, tv, pr_addr(from, sizeof *from),
-				      pr_echo_reply)) {
+				      pr_echo_reply,
+				      multicast)) {
 			fflush(stdout);
 			return 0;
 		}
@@ -1221,7 +1224,8 @@ ping6_parse_reply(socket_st *sock, struct msghdr *msg, int cc, void *addr, struc
 		if (gather_statistics((uint8_t *)icmph, sizeof(*icmph), cc,
 				      seq,
 				      hops, 0, tv, pr_addr(from, sizeof *from),
-				      pr_niquery_reply))
+				      pr_niquery_reply,
+				      multicast))
 			return 0;
 	} else {
 		int nexthdr;
diff --git a/ping_common.c b/ping_common.c
index 73b76fa..e91d15c 100644
--- a/ping_common.c
+++ b/ping_common.c
@@ -781,7 +781,7 @@ void main_loop(ping_func_set_st *fset, socket_st *sock, uint8_t *packet, int pac
 int gather_statistics(uint8_t *icmph, int icmplen,
 		      int cc, uint16_t seq, int hops,
 		      int csfailed, struct timeval *tv, char *from,
-		      void (*pr_reply)(uint8_t *icmph, int cc))
+		      void (*pr_reply)(uint8_t *icmph, int cc), int multicast)
 {
 	int dupflag = 0;
 	long triptime = 0;
@@ -874,7 +874,7 @@ restamp:
 				printf(_(" time=%ld.%03ld ms"), triptime / 1000,
 				       triptime % 1000);
 		}
-		if (dupflag)
+		if (dupflag && (!multicast || options & F_VERBOSE))
 			printf(_(" (DUP!)"));
 		if (csfailed)
 			printf(_(" (BAD CHECKSUM!)"));