[monit-dev] [monit] r288 committed - Remove the experimental usleep - it seems the echo request is external...

[monit]

Revision: 288
Author: martin2812
Date: Sun Sep 26 15:54:17 2010
Log: Remove the experimental usleep - it seems the echo request is external.

Theory no. 2: Testing farm is set for bi-directinal ping (both hosts  
pinging to each other),
it is possible that the icmp request received instead of expected response  
is originated
by the other host and since we have raw socket open with it and awaiting  
response, we receive
his requests too, i.e. race condition where two hosts are pinging each  
other, both send echo
request at once and expect reply, but instead of reply, request is received  
by application.

Setting icmp id to pid (which is used by standalone ping program too) +  
print out the id of
unexpected echo request ... if it is from the other host's monit, we'll see  
its pid in log.



http://code.google.com/p/monit/source/detail?r=288

Modified:
 /trunk/net.c

=======================================
--- /trunk/net.c        Sun Sep 26 11:45:11 2010
+++ /trunk/net.c        Sun Sep 26 15:54:17 2010
@@ -702,7 +702,7 @@
   }
 #endif

-  id_out = (getpid() + time(NULL)) & 0xFFFF;
+  id_out = getpid() & 0xFFFF;
   icmpout = (struct icmp *)buf;
   for (i = 0; i < count; i++) {
     int j;
@@ -738,13 +738,6 @@
       continue;
     }

-    /* Experimental: it seems monit sporadically reads its own ICMP echo  
request if the request is sent to the
-     * same host's network interface (such as for virtual hosts running on  
the same machine), whereas the raw
-     * socket seems to read it before target host gets the request. Need  
to investiagte it more, trying to delay
-     * the read to see if there will be difference (we see the transient  
1/3 attempt failure sporadically on testing
-     * farm */
-    usleep(100);
-
     if (can_read(s, timeout)) {
       socklen_t size = sizeof(struct sockaddr_in);

@@ -770,7 +763,9 @@
           DEBUG("ICMP echo response %d/%d succeeded -- received id=%d  
sequence=%d response_time=%fs\n", i + 1, count, icmpin->icmp_id,  
icmpin->icmp_seq, response);
           break; // Wait for one response only
         } else
-          LogError("ICMP echo response %d/%d error -- received id=%d  
(expected id=%d), received sequence=%d (expected sequence 0-%d)\n", i + 1,  
count, icmpin->icmp_id, id_out, icmpin->icmp_seq, count - 1);
+          LogError("ICMP echo response %d/%d error -- received id=%d  
(expected id=%d), received sequence=%d (expected sequence=%d)\n", i + 1,  
count, icmpin->icmp_id, id_out, icmpin->icmp_seq, count - 1);
+      } else if (icmpin->icmp_type == ICMP_ECHO) {
+        LogError("ICMP echo response %d/%d failed -- received echo request  
instead of expected response, source id=%d (mine id=%d) sequence=%d (mine  
sequence=%d)\n", i + 1, count, icmpin->icmp_id, id_out, icmpin->icmp_seq,  
count - 1);
       } else
         LogError("ICMP echo response %d/%d failed -- invalid ICMP response  
type: %x (%s)\n", i + 1, count, icmpin->icmp_type, icmpin->icmp_type < 19 ?  
icmpnames[icmpin->icmp_type] : "unknown");
     } else