Add --repeating-payload option to the client side (#726)

This option simulates payload in iperf2, which is just repetitive pattern
(ASCII '0..9' repeating), as opposed to iperf3 where payload is random.
It might help in testing and reveal problems in networking gear with hardware
compression (including WiFi access points), where iperf2 and iperf3 perform
differently, just based on payload entropy.

src/iperf.h

@@ -273,6 +273,7 @@ struct iperf_test
     int	      udp_counters_64bit;		/* --use-64-bit-udp-counters */
     int       forceflush; /* --forceflush - flushing output at every interval */
     int	      multisend;
+    int	      repeating_payload;                /* --repeating-payload */
 
     char     *json_output_string; /* rendered JSON output if json_output is set */
     /* Select related parameters */

src/iperf3.1

@@ -350,6 +350,13 @@ If the client is run with \fB--json\fR, the server output is included
 in a JSON object; otherwise it is appended at the bottom of the
 human-readable output.
 .TP
+.BR --repeating-payload
+Use repeating pattern in payload, instead of random bytes.
+The same payload is used in iperf2 (ASCII '0..9' repeating).
+It might help to test and reveal problems in networking gear with hardware
+compression (including some WiFi access points), where iperf2 and iperf3
+perform differently, just based on payload entropy.
+.TP
 .BR --username " \fIusername\fR" 
 username to use for authentication to the iperf server (if built with
 OpenSSL support).

src/iperf_api.c

@@ -673,6 +673,7 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
         {"zerocopy", no_argument, NULL, 'Z'},
         {"omit", required_argument, NULL, 'O'},
         {"file", required_argument, NULL, 'F'},
+        {"repeating-payload", no_argument, NULL, OPT_REPEATING_PAYLOAD},
 #if defined(HAVE_CPU_AFFINITY)
         {"affinity", required_argument, NULL, 'A'},
 #endif /* HAVE_CPU_AFFINITY */
@@ -951,6 +952,10 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
                 test->zerocopy = 1;
 		client_flag = 1;
                 break;
+            case OPT_REPEATING_PAYLOAD:
+                test->repeating_payload = 1;
+                client_flag = 1;
+                break;
             case 'O':
                 test->omit = atoi(optarg);
                 if (test->omit < 0 || test->omit > 60) {
@@ -3175,6 +3180,7 @@ struct iperf_stream *
 iperf_new_stream(struct iperf_test *test, int s)
 {
     struct iperf_stream *sp;
+    int ret = 0;
 
     char template[1024];
     if (test->tmp_template) {
@@ -3265,8 +3271,12 @@ iperf_new_stream(struct iperf_test *test, int s)
         sp->diskfile_fd = -1;
 
     /* Initialize stream */
-    if ((readentropy(sp->buffer, test->settings->blksize) < 0) ||
+    if (test->repeating_payload)
-        (iperf_init_stream(sp, test) < 0)) {
+        fill_with_repeating_pattern(sp->buffer, test->settings->blksize);
+    else
+        ret = readentropy(sp->buffer, test->settings->blksize);
+
+    if ((ret < 0) || (iperf_init_stream(sp, test) < 0)) {
         close(sp->buffer_fd);
         munmap(sp->buffer, sp->test->settings->blksize);
         free(sp->result);

src/iperf_api.h

@@ -68,6 +68,7 @@ struct iperf_stream;
 #define OPT_SERVER_AUTHORIZED_USERS 15
 #define OPT_PACING_TIMER 16
 #define OPT_CONNECT_TIMEOUT 17
+#define OPT_REPEATING_PAYLOAD 18
 
 /* states */
 #define TEST_START 1

src/iperf_locale.c

@@ -171,6 +171,8 @@ const char usage_longstr[] = "Usage: iperf3 [-s|-c host] [options]\n"
                            "  -T, --title str           prefix every output line with this string\n"
                            "  --get-server-output       get results from server\n"
                            "  --udp-counters-64bit      use 64-bit counters in UDP test packets\n"
+                           "  --repeating-payload       use repeating pattern in payload, instead of\n"
+                           "                            randomized payload (like in iperf2)\n"
 #if defined(HAVE_SSL)
                            "  --username                username for authentication\n"
                            "  --rsa-public-key-path     path to the RSA public key used to encrypt\n"

src/iperf_util.c

@@ -79,6 +79,27 @@ int readentropy(void *out, size_t outsize)
 }
 
 
+/*
+ * Fills buffer with repeating pattern (similar to pattern that used in iperf2)
+ */
+void fill_with_repeating_pattern(void *out, size_t outsize)
+{
+    size_t i;
+    int counter = 0;
+    char *buf = (char *)out;
+
+    if (!outsize) return;
+
+    for (i = 0; i < outsize; i++) {
+        buf[i] = (char)('0' + counter);
+        if (counter >= 9)
+            counter = 0;
+        else
+            counter++;
+    }
+}
+
+
 /* make_cookie
  *
  * Generate and return a cookie string

src/iperf_util.h

@@ -34,6 +34,8 @@
 
 int readentropy(void *out, size_t outsize);
 
+void fill_with_repeating_pattern(void *out, size_t outsize);
+
 void make_cookie(char *);
 
 int is_closed(int);