Add --imix CLI option

Will be used to switch on imix traffic pattern.

src/iperf.h

@@ -167,6 +167,7 @@ struct iperf_settings
     int       idle_timeout;         /* server idle time timeout */
     unsigned int snd_timeout; /* Timeout for sending tcp messages in active mode, in us */
     struct iperf_time rcv_timeout;  /* Timeout for receiving messages in active mode, in us */
+    int       imix;                 /* Whether to send internet mix traffic */
 };
 
 struct iperf_test;

src/iperf3.1

@@ -422,6 +422,10 @@ or high-bitrate UDP tests.  Both client and server need to be running
 at least version 3.1 for this option to work.  It may become the
 default behavior at some point in the future.
 .TP
+.BR --imix
+Use internet mix traffic pattern instead of maximum possible payload size.
+This is useful for testing middleboxes.
+.TP
 .BR --repeating-payload
 Use repeating pattern in payload, instead of random bytes.
 The same payload is used in iperf2 (ASCII '0..9' repeating).

src/iperf_api.c

@@ -1065,6 +1065,7 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
         {"bitrate", required_argument, NULL, 'b'},
         {"bandwidth", required_argument, NULL, 'b'},
 	{"server-bitrate-limit", required_argument, NULL, OPT_SERVER_BITRATE_LIMIT},
+        {"imix", no_argument, NULL, OPT_IMIX},
         {"time", required_argument, NULL, 't'},
         {"bytes", required_argument, NULL, 'n'},
         {"blockcount", required_argument, NULL, 'k'},
@@ -1618,6 +1619,9 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 		test->settings->connect_timeout = unit_atoi(optarg);
 		client_flag = 1;
 		break;
+	    case OPT_IMIX:
+		test->settings->imix = 1;
+		break;
 	    case 'h':
 		usage_long(stdout);
 		exit(0);
@@ -1766,6 +1770,24 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
         return -1;
     }
 
+    /* Using 64-bit counters goes over 40 byte (incl. ip and udp hdr) pkt size class */
+    if (test->udp_counters_64bit && test->settings->imix) {
+        i_errno = IEUDPCOUNTERIMIX;
+        return -1;
+    }
+
+    /* IPv6 header is too big to fit into smallest pkt size class */
+    if (test->settings->imix && test->settings->domain != AF_INET) {
+        i_errno = IEUDPINET6IMIX;
+        return -1;
+    }
+
+    /* Cannot easily control packet size on the wire unless it's UDP */
+    if (test->settings->imix && test->protocol->id != Pudp) {
+        i_errno = IEIMIXNOTUDP;
+        return -1;
+    }
+
     /* For subsequent calls to getopt */
 #ifdef __APPLE__
     optreset = 1;

src/iperf_api.h

@@ -90,6 +90,7 @@ typedef uint64_t iperf_size_t;
 #define OPT_DONT_FRAGMENT 26
 #define OPT_RCV_TIMEOUT 27
 #define OPT_SND_TIMEOUT 28
+#define OPT_IMIX 29
 
 /* states */
 #define TEST_START 1
@@ -406,6 +407,9 @@ enum {
     IERVRSONLYRCVTIMEOUT = 32,  // Client receive timeout is valid only in reverse mode
     IESNDTIMEOUT = 33,      // Illegal message send timeout
     IEUDPFILETRANSFER = 34, // Cannot transfer file using UDP
+    IEUDPCOUNTERIMIX = 35,  // 64 bit counter too big for imix
+    IEUDPINET6IMIX = 36,    // IPv6 header too big for imix
+    IEIMIXNOTUDP = 37,      // IMIX mode cannot be used for non UDP
     /* Test errors */
     IENEWTEST = 100,        // Unable to create a new test (check perror)
     IEINITTEST = 101,       // Test initialization failed (check perror)

src/iperf_error.c

@@ -355,6 +355,15 @@ iperf_strerror(int int_errno)
         case IEUDPFILETRANSFER:
             snprintf(errstr, len, "cannot transfer file using UDP");
             break;
+        case IEUDPCOUNTERIMIX:
+            snprintf(errstr, len, "64 bit counter makes small imix packet too large");
+            break;
+        case IEUDPINET6IMIX:
+            snprintf(errstr, len, "ipv6 header makes small imix packet too large");
+            break;
+        case IEIMIXNOTUDP:
+            snprintf(errstr, len, "imix can only be used for udp");
+            break;
         case IERVRSONLYRCVTIMEOUT:
             snprintf(errstr, len, "client receive timeout is valid only in receiving mode");
             perr = 1;

src/iperf_locale.c

@@ -211,6 +211,7 @@ const char usage_longstr[] = "Usage: iperf3 [-s|-c host] [options]\n"
                            "  --extra-data str          data string to include in client and server JSON\n"
                            "  --get-server-output       get results from server\n"
                            "  --udp-counters-64bit      use 64-bit counters in UDP test packets\n"
+                           "  --imix                    use IMIX traffic pattern\n"
                            "  --repeating-payload       use repeating pattern in payload, instead of\n"
                            "                            randomized payload (like in iperf2)\n"
 #if defined(HAVE_DONT_FRAGMENT)