Add support for specifying client-side epemeral port

-e/--cport now allows a user to specify the client-side port
used for data transfer.

Signed-off-by: Kevin Constantine <kevin.constantine@gmail.com>

src/iperf.h

@@ -172,6 +172,7 @@ struct iperf_test
     signed char state;
     char     *server_hostname;                  /* -c option */
     char     *bind_address;                     /* -B option */
+    int      *bind_port;                        /* -e option */
     int       server_port;
     int       omit;                             /* duration of omit period (-O flag) */
     int       duration;                         /* total duration of test (-t flag) */

src/iperf_api.c

@@ -584,6 +584,7 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
         {"reverse", no_argument, NULL, 'R'},
         {"window", required_argument, NULL, 'w'},
         {"bind", required_argument, NULL, 'B'},
+        {"cport", required_argument, NULL, 'e'},
         {"set-mss", required_argument, NULL, 'M'},
         {"no-delay", no_argument, NULL, 'N'},
         {"version4", no_argument, NULL, '4'},
@@ -624,7 +625,7 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 
     blksize = 0;
     server_flag = client_flag = rate_flag = duration_flag = 0;
-    while ((flag = getopt_long(argc, argv, "p:f:i:DVJvsc:ub:t:n:k:l:P:Rw:B:M:N46S:L:ZO:F:A:T:C:dI:h", longopts, NULL)) != -1) {
+    while ((flag = getopt_long(argc, argv, "p:f:i:DVJvsc:ub:t:n:k:l:P:Rw:B:e:M:N46S:L:ZO:F:A:T:C:dI:h", longopts, NULL)) != -1) {
         switch (flag) {
             case 'p':
                 test->server_port = atoi(optarg);
@@ -745,6 +746,9 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
             case 'B':
                 test->bind_address = strdup(optarg);
                 break;
+            case 'e':
+                test->bind_port = atoi(optarg);
+                break;
             case 'M':
                 test->settings->mss = atoi(optarg);
                 if (test->settings->mss > MAX_MSS) {
@@ -876,6 +880,10 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 	return -1;
     }
 
+    if (!test->bind_address && test->bind_port) {
+        i_errno = IEBIND;
+        return -1;
+    }
     if (blksize == 0) {
 	if (test->protocol->id == Pudp)
 	    blksize = DEFAULT_UDP_BLKSIZE;

src/iperf_api.h

@@ -262,6 +262,7 @@ enum {
     IEENDCONDITIONS = 16,   // Only one test end condition (-t, -n, -k) may be specified
     IELOGFILE = 17,	    // Can't open log file
     IENOSCTP = 18,	    // No SCTP support available
+    IEBIND = 19,			// Local port specified with no local bind option
     /* Test errors */
     IENEWTEST = 100,        // Unable to create a new test (check perror)
     IEINITTEST = 101,       // Test initialization failed (check perror)

src/iperf_error.c

@@ -104,6 +104,9 @@ iperf_strerror(int i_errno)
         case IEINTERVAL:
             snprintf(errstr, len, "invalid report interval (min = %g, max = %g seconds)", MIN_INTERVAL, MAX_INTERVAL);
             break;
+        case IEBIND:
+            snprintf(errstr, len, "--bind must be specified to use --cport");
+            break;
         case IEMSS:
             snprintf(errstr, len, "TCP MSS too large (maximum = %d bytes)", MAX_MSS);
             break;

src/iperf_tcp.c

@@ -325,6 +325,11 @@ iperf_tcp_connect(struct iperf_test *test)
     }
 
     if (test->bind_address) {
+        struct sockaddr_in *lcladdr;
+        lcladdr = (struct sockaddr_in *)local_res->ai_addr;
+        lcladdr->sin_port = htons(test->bind_port);
+        local_res->ai_addr = (struct sockaddr *)lcladdr;
+
         if (bind(s, (struct sockaddr *) local_res->ai_addr, local_res->ai_addrlen) < 0) {
 	    saved_errno = errno;
 	    close(s);

src/locale.c

@@ -108,6 +108,7 @@ const char usage_longstr[] = "Usage: iperf [-s|-c host] [options]\n"
                            "  -k, --blockcount #[KMG]   number of blocks (packets) to transmit (instead of -t or -n)\n"
                            "  -l, --len       #[KMG]    length of buffer to read or write\n"
 			   "                            (default %d KB for TCP, %d KB for UDP)\n"
+                           "  -e, --cport     <host>    bind to a specific client port (default: ephemeral port)\n"
                            "  -P, --parallel  #         number of parallel client streams to run\n"
                            "  -R, --reverse             run in reverse mode (server sends, client receives)\n"
                            "  -w, --window    #[KMG]    TCP window size (socket buffer size)\n"
@@ -171,6 +172,9 @@ const char client_port[] =
 const char bind_address[] =
 "Binding to local address %s\n";
 
+const char bind_port[] =
+"Binding to local port %s\n";
+
 const char multicast_ttl[] =
 "Setting multicast TTL to %d\n";