Add optional setting of server congestion control algorithm

src/iperf.h

@@ -318,6 +318,7 @@ struct iperf_test
     char     *title;				/* -T option */
     char     *extra_data;			/* --extra-data */
     char     *congestion;			/* -C option */
+    char     *congestion_server;		/* -C option - used only in the client side to pass the `congestion` value to the server */
     char     *congestion_used;			/* what was actually used */
     char     *remote_congestion_used;		/* what the other side used */
     char     *pidfile;				/* -P option */

src/iperf_api.c

@@ -428,6 +428,12 @@ iperf_get_test_congestion_control(struct iperf_test* ipt)
     return ipt->congestion;
 }
 
+char*
+iperf_get_test_congestion_control_server(struct iperf_test* ipt)
+{
+    return ipt->congestion_server;
+}
+
 int
 iperf_get_test_mss(struct iperf_test *ipt)
 {
@@ -848,6 +854,12 @@ iperf_set_test_congestion_control(struct iperf_test* ipt, char* cc)
     ipt->congestion = strdup(cc);
 }
 
+void
+iperf_set_test_congestion_server_control_server(struct iperf_test* ipt, char* cc)
+{
+    ipt->congestion_server = strdup(cc);
+}
+
 void
 iperf_set_test_mss(struct iperf_test *ipt, int mss)
 {
@@ -1128,10 +1140,8 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
         {"affinity", required_argument, NULL, 'A'},
 #endif /* HAVE_CPU_AFFINITY */
         {"title", required_argument, NULL, 'T'},
-#if defined(HAVE_TCP_CONGESTION)
         {"congestion", required_argument, NULL, 'C'},
         {"linux-congestion", required_argument, NULL, 'C'},
-#endif /* HAVE_TCP_CONGESTION */
 #if defined(HAVE_SCTP_H)
         {"sctp", no_argument, NULL, OPT_SCTP},
         {"nstreams", required_argument, NULL, OPT_NUMSTREAMS},
@@ -1613,13 +1623,30 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 		client_flag = 1;
                 break;
 	    case 'C':
-#if defined(HAVE_TCP_CONGESTION)
-		test->congestion = strdup(optarg);
+                if (optarg) {
+                    slash = strchr(optarg, '/');
+		    if (slash) {
+		        *slash = '\0';
+		        ++slash;
+                        if (strlen(slash) > 0) {
+                            test->congestion_server = strdup(slash);
+                        }
+                    }
+                    if (strlen(optarg) > 0) {
+                        test->congestion = strdup(optarg);
+                        if (!test->congestion_server) {
+                            test->congestion_server = strdup(test->congestion);
+                        }
+                    }
+                }
 		client_flag = 1;
-#else /* HAVE_TCP_CONGESTION */
-		i_errno = IEUNIMP;
-		return -1;
+#ifndef HAVE_TCP_CONGESTION
+		if (test->congestion) { // Client does not support congestion control, so should not be set for the client
+                    i_errno = IECONGESTIONSUPPORT;
+		    return -1;
+                }
 #endif /* HAVE_TCP_CONGESTION */
+
 		break;
 	    case 'd':
 		test->debug = 1;
@@ -1885,6 +1912,14 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
         return -1;
     }
 
+    // Warning if congestion control algorithm was set to non-sending client or server
+    if (test->congestion != NULL && test->mode == RECEIVER) {
+        warning("Congestion control algorithm was set to non-sending client");
+    }
+    if (test->congestion == NULL && test->congestion_server != NULL && test->mode == SENDER) {
+        warning("Congestion control algorithm was set to non-sending server");
+    }
+
     /* Set Total-rate average interval to multiplicity of State interval */
     if (test->settings->bitrate_limit_interval != 0) {
 	test->settings->bitrate_limit_stats_per_interval =
@@ -2373,8 +2408,8 @@ send_parameters(struct iperf_test *test)
 	    cJSON_AddStringToObject(j, "title", test->title);
 	if (test->extra_data)
 	    cJSON_AddStringToObject(j, "extra_data", test->extra_data);
-	if (test->congestion)
-	    cJSON_AddStringToObject(j, "congestion", test->congestion);
+	if (test->congestion_server)
+	    cJSON_AddStringToObject(j, "congestion", test->congestion_server);
 	if (test->congestion_used)
 	    cJSON_AddStringToObject(j, "congestion_used", test->congestion_used);
 	if (test->get_server_output)
@@ -3280,6 +3315,8 @@ iperf_free_test(struct iperf_test *test)
 	free(test->extra_data);
     if (test->congestion)
 	free(test->congestion);
+    if (test->congestion_server)
+	free(test->congestion_server);
     if (test->congestion_used)
 	free(test->congestion_used);
     if (test->remote_congestion_used)
@@ -3395,6 +3432,8 @@ iperf_reset_test(struct iperf_test *test)
 
     if (test->congestion)
         free(test->congestion);
+    if (test->congestion_server)
+	free(test->congestion_server);
     test->congestion = NULL;
     if (test->remote_congestion_used)
         free(test->remote_congestion_used);

src/iperf_api.h

@@ -169,6 +169,7 @@ int	iperf_get_test_no_delay( struct iperf_test* ipt );
 int	iperf_get_test_connect_timeout( struct iperf_test* ipt );
 int	iperf_get_dont_fragment( struct iperf_test* ipt );
 char*   iperf_get_test_congestion_control(struct iperf_test* ipt);
+char*   iperf_get_test_congestion_control_server(struct iperf_test* ipt);
 int iperf_get_test_mss(struct iperf_test* ipt);
 int     iperf_get_mapped_v4(struct iperf_test* ipt);
 
@@ -215,6 +216,7 @@ void    iperf_set_test_bidirectional( struct iperf_test* ipt, int bidirectional)
 void    iperf_set_test_no_delay( struct iperf_test* ipt, int no_delay);
 void    iperf_set_dont_fragment( struct iperf_test* ipt, int dont_fragment );
 void    iperf_set_test_congestion_control(struct iperf_test* ipt, char* cc);
+void    iperf_set_test_congestion_control_server(struct iperf_test* ipt, char* cc);
 void    iperf_set_test_mss(struct iperf_test* ipt, int mss);
 void    iperf_set_mapped_v4(struct iperf_test* ipt, const int val);
 void    iperf_set_on_new_stream_callback(struct iperf_test* ipt, void (*callback)(struct iperf_stream *));
@@ -495,6 +497,7 @@ enum {
     IESETCNTLKAINTERVAL = 157, // Unable to set/get socket keepalive TCP retry interval (TCP_KEEPINTVL) option
     IESETCNTLKACOUNT = 158,    // Unable to set/get socket keepalive TCP number of retries (TCP_KEEPCNT) option
     IEPTHREADSIGMASK=159,      // Unable to initialize sub thread signal mask (check perror)
+    IECONGESTIONSUPPORT = 160, // Client does not support setting TCP congestion control algorithm
     /* Stream errors */
     IECREATESTREAM = 200,   // Unable to create a new stream (check herror/perror)
     IEINITSTREAM = 201,     // Unable to initialize stream (check herror/perror)

src/iperf_error.c

@@ -449,6 +449,9 @@ iperf_strerror(int int_errno)
             snprintf(errstr, len, "unable to update timer");
             perr = 1;
             break;
+        case IECONGESTIONSUPPORT:
+            snprintf(errstr, len, "Client does not support setting TCP congestion control algorithm");
+            break;
         case IESETCONGESTION:
             snprintf(errstr, len, "unable to set TCP_CONGESTION: "
                                   "Supplied congestion control algorithm not supported on this host");

src/iperf_locale.c

@@ -192,7 +192,10 @@ const char usage_longstr[] = "Usage: iperf3 [-s|-c host] [options]\n"
                            "                            (indirectly sets TCP window size)\n"
 
 #if defined(HAVE_TCP_CONGESTION)
-                           "  -C, --congestion <algo>   set TCP congestion control algorithm (Linux and FreeBSD only)\n"
+                           "  -C, --congestion <algo>[/<server_algo>] set TCP congestion control algorithm (Linux and FreeBSD only)\n"
+                           "                            <algo> for client & server, optional <algo_server> for the server\n"
+#else /* HAVE_TCP_CONGESTION */
+                           "  -C, --congestion /<server_algo> set server TCP congestion control algorithm\n"
 #endif /* HAVE_TCP_CONGESTION */
                            "  -M, --set-mss   #         set TCP/SCTP maximum segment size (MTU - 40 bytes)\n"
                            "  -N, --no-delay            set TCP/SCTP no delay, disabling Nagle's Algorithm\n"

src/iperf_server_api.c

@@ -533,7 +533,7 @@ iperf_run_server(struct iperf_test *test)
     int result, s;
     int send_streams_accepted, rec_streams_accepted;
     int streams_to_send = 0, streams_to_rec = 0;
-#if defined(HAVE_TCP_CONGESTION)
+#if defined(HAVE_TCP_CONGESTION) || defined(HAVE_TCP_USER_TIMEOUT)
     int saved_errno;
 #endif /* HAVE_TCP_CONGESTION */
     fd_set read_set, write_set;