[PATCH 2/2] [iputils] Use PMTUDISC_PROBE mode if it exists.

[John Heffner]

Signed-off-by: John Heffner <[EMAIL PROTECTED]>
---
 tracepath.c  |   10 ++++++++--
 tracepath6.c |   10 ++++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/tracepath.c b/tracepath.c
index 1f901ba..a562d88 100644
--- a/tracepath.c
+++ b/tracepath.c
@@ -24,6 +24,10 @@
 #include <sys/uio.h>
 #include <arpa/inet.h>
 
+#ifndef IP_PMTUDISC_PROBE
+#define IP_PMTUDISC_PROBE      3
+#endif
+
 struct hhistory
 {
        int     hops;
@@ -322,8 +326,10 @@ main(int argc, char **argv)
        }
        memcpy(&target.sin_addr, he->h_addr, 4);
 
-       on = IP_PMTUDISC_DO;
-       if (setsockopt(fd, SOL_IP, IP_MTU_DISCOVER, &on, sizeof(on))) {
+       on = IP_PMTUDISC_PROBE;
+       if (setsockopt(fd, SOL_IP, IP_MTU_DISCOVER, &on, sizeof(on)) &&
+           (on = IP_PMTUDISC_DO,
+            setsockopt(fd, SOL_IP, IP_MTU_DISCOVER, &on, sizeof(on)))) {
                perror("IP_MTU_DISCOVER");
                exit(1);
        }
diff --git a/tracepath6.c b/tracepath6.c
index d65230d..6f13a51 100644
--- a/tracepath6.c
+++ b/tracepath6.c
@@ -30,6 +30,10 @@
 #define SOL_IPV6 IPPROTO_IPV6
 #endif
 
+#ifndef IPV6_PMTUDISC_PROBE
+#define IPV6_PMTUDISC_PROBE    3
+#endif
+
 int overhead = 48;
 int mtu = 128000;
 int hops_to = -1;
@@ -369,8 +373,10 @@ int main(int argc, char **argv)
                mapped = 1;
        }
 
-       on = IPV6_PMTUDISC_DO;
-       if (setsockopt(fd, SOL_IPV6, IPV6_MTU_DISCOVER, &on, sizeof(on))) {
+       on = IPV6_PMTUDISC_PROBE;
+       if (setsockopt(fd, SOL_IPV6, IPV6_MTU_DISCOVER, &on, sizeof(on)) &&
+           (on = IPV6_PMTUDISC_DO,
+            setsockopt(fd, SOL_IPV6, IPV6_MTU_DISCOVER, &on, sizeof(on)))) {
                perror("IPV6_MTU_DISCOVER");
                exit(1);
        }
-- 
1.5.0.2.gc260-dirty

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