Change default time period to 30s and relax default loss interval to 5x send interval to address nagging low level loss reports

Add usage note about loss percentage reporting and calculation

dpinger.c

@@ -52,6 +52,18 @@
 #include <pthread.h>
 #include <syslog.h>
 
+// TODO:
+//
+// After December 31st, 2016, review use of fcntl() for setting non blocking
+// and close on exec. It would be preferable to use accept4(), SOCK_CLOEXEC
+// and SOCK_NONBLOCK. These are currently avoided to allow use on older
+// systems such as FreeBSD 9.3, Linux 2.6.26.
+// For Linux accept4() currently requires defining _GNU_SOURCE which we would
+// like to avoid.
+// For FreeBSD, these definitions were introduced with FreeBSD 10.0 and are
+// not present in 9.3 which is supported through 2016.
+
+
 // Who we are
 static const char *             progname;
 
@@ -68,7 +80,7 @@ static unsigned int             flag_syslog = 0;
 static char                     dest_str[ADDR_STR_MAX];
 
 // Time period over which we are averaging results in ms
-static unsigned long            time_period_msec = 25000;
+static unsigned long            time_period_msec = 30000;
 
 // Interval between sends in ms
 static unsigned long            send_interval_msec = 250;
@@ -665,6 +677,7 @@ usocket_thread(
     while (1)
     {
         sock_fd = accept(usocket_fd, NULL, NULL);
+        (void) fcntl(sock_fd, F_SETFL, FD_CLOEXEC);
         (void) fcntl(sock_fd, F_SETFL, fcntl(sock_fd, F_GETFL, 0) | O_NONBLOCK);
 
         report(&average_latency_usec, &latency_deviation, &average_loss_percent);
@@ -775,8 +788,8 @@ usage(void)
     fprintf(stderr, "    -S log warnings via syslog\n");
     fprintf(stderr, "    -B bind (source) address\n");
     fprintf(stderr, "    -s time interval between echo requests (default 250ms)\n");
-    fprintf(stderr, "    -l time interval before packets are treated as lost (default 2x send interval)\n");
-    fprintf(stderr, "    -t time period over which results are averaged (default 25s)\n");
+    fprintf(stderr, "    -l time interval before packets are treated as lost (default 5x send interval)\n");
+    fprintf(stderr, "    -t time period over which results are averaged (default 30s)\n");
     fprintf(stderr, "    -r time interval between reports (default 1s)\n");
     fprintf(stderr, "    -o output file for reports (default stdout)\n");
     fprintf(stderr, "    -A time interval between alerts (default 1s)\n");
@@ -787,11 +800,13 @@ usage(void)
     fprintf(stderr, "    -u unix socket name for polling\n");
     fprintf(stderr, "    -p process id file name\n\n");
     fprintf(stderr, "  notes:\n");
+    fprintf(stderr, "    IP addresses can be in either IPv4 or IPv6 format\n\n");
     fprintf(stderr, "    time values can be expressed with a suffix of 'm' (milliseconds) or 's' (seconds)\n");
     fprintf(stderr, "    if no suffix is specified, milliseconds is the default\n\n");
-    fprintf(stderr, "    IP addresses can be in either IPv4 or IPv6 format\n\n");
     fprintf(stderr, "    the output format is \"latency_avg latency_stddev loss_pct\"\n");
-    fprintf(stderr, "    latency values are output in microseconds\n\n");
+    fprintf(stderr, "    latency values are output in microseconds\n");
+    fprintf(stderr, "    loss percentage is reported in whole numbers of 0-100\n");
+    fprintf(stderr, "    resolution of loss calculation is: 100 * send_interval / (time_period - loss_interval)\n\n");
     fprintf(stderr, "    the alert_cmd is invoked as \"alert_cmd dest_addr alarm_flag latency_avg loss_avg\"\n");
     fprintf(stderr, "    alarm_flag is set to 1 if either latency or loss is in alarm state\n");
     fprintf(stderr, "    alarm_flag will return to 0 when both have have cleared alarm state\n\n");
@@ -1038,7 +1053,7 @@ main(
     char                        *argv[])
 {
     char                        bind_str[ADDR_STR_MAX] = "(none)";
-    int                         pidfile_fd;
+    int                         pidfile_fd = -1;
     pthread_t                   thread;
     struct                      sigaction act;
     int                         r;
@@ -1053,12 +1068,15 @@ main(
         perror("socket");
         fatal("cannot create send socket\n");
     }
+    (void) fcntl(send_sock, F_SETFL, FD_CLOEXEC);
+
     recv_sock = socket(af_family, SOCK_RAW, ip_proto);
     if (recv_sock == -1)
     {
         perror("socket");
         fatal("cannot create recv socket\n");
     }
+    (void) fcntl(recv_sock, F_SETFL, FD_CLOEXEC);
 
     // Bind our sockets to an address if requested
     if (bind_addr_len)
@@ -1084,7 +1102,7 @@ main(
     // Create report file
     if (report_name)
     {
-        report_fd = open(report_name, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+        report_fd = open(report_name, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
         if (report_fd == -1)
         {
             perror("open");
@@ -1106,12 +1124,13 @@ main(
             fatal("socket name too large\n");
         }
 
-        usocket_fd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
+        usocket_fd = socket(AF_UNIX, SOCK_STREAM, 0);
         if (usocket_fd == -1)
         {
             perror("socket");
             fatal("cannot create unix domain socket\n");
         }
+        (void) fcntl(usocket_fd, F_SETFL, FD_CLOEXEC);
 
         (void) unlink(usocket_name);
 
@@ -1143,7 +1162,7 @@ main(
     // Create pid file
     if (pidfile_name)
     {
-        pidfile_fd = open(pidfile_name, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+        pidfile_fd = open(pidfile_name, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
         if (pidfile_fd == -1)
         {
             perror("open");
@@ -1179,7 +1198,7 @@ main(
     sigaction(SIGINT, &act, NULL);
 
     // Write pid file
-    if (pidfile_name)
+    if (pidfile_fd != -1)
     {
         char                    buf[64];
         int                     len;
@@ -1197,7 +1216,7 @@ main(
             fatal("error writing pidfile\n");
         }
 
-        r= close(pidfile_fd);
+        r = close(pidfile_fd);
         if (r == -1)
         {
             perror("close");
@@ -1216,7 +1235,7 @@ main(
     // Set the default loss interval
     if (loss_interval_msec == 0)
     {
-        loss_interval_msec = send_interval_msec * 4;
+        loss_interval_msec = send_interval_msec * 5;
     }
     loss_interval_usec = loss_interval_msec * 1000;