[iputils] tracepath: Re-probe at same TTL after MTU reduction.

This fixes a bug that would miss a hop after an ICMP packet too big message,
since it would continue increase the TTL without probing again.

Signed-off-by: YOSHIFUJI Hideaki <[email protected]>

Author: John Heffner

tracepath.c

@@ -352,8 +352,14 @@ main(int argc, char **argv)
 			exit(1);
 		}
 
+restart:
 		for (i=0; i<3; i++) {
+			int old_mtu;
+
+			old_mtu = mtu;
 			res = probe_ttl(fd, ttl);
+			if (mtu != old_mtu)
+				goto restart;
 			if (res == 0)
 				goto done;
 			if (res > 0)

tracepath6.c

@@ -422,8 +422,14 @@ int main(int argc, char **argv)
 			exit(1);
 		}
 
+restart:
 		for (i=0; i<3; i++) {
+			int old_mtu;
+
+			old_mtu = mtu;
 			res = probe_ttl(fd, ttl);
+			if (mtu != old_mtu)
+				goto restart;
 			if (res == 0)
 				goto done;
 			if (res > 0)