Ignore out of order packts during UDP connection in Reverse Mode

src/iperf.h

@@ -421,4 +421,12 @@ struct iperf_test
 
 extern int gerror; /* error value from getaddrinfo(3), for use in internal error handling */
 
+/* UDP "connect" message and reply (textual value for Wireshark, etc. readability - legacy was numeric) */
+#define UDP_CONNECT_MSG 0x36373839          // "6789" - legacy value was 123456789
+#define UDP_CONNECT_REPLY 0x39383736        // "9876" - legacy value was 987654321
+#define LEGACY_UDP_CONNECT_REPLY 987654321  // Old servers may still reply with the legacy value
+
+/* In Reverse mode, maxmimum number of packtes to wait for "accept" response - to handle out of order packets */
+#define MAX_REVERSE_OUT_OF_ORDER_PACKETS 2
+
 #endif /* !__IPERF_H */

src/iperf_udp.c

@@ -365,7 +365,7 @@ int
 iperf_udp_accept(struct iperf_test *test)
 {
     struct sockaddr_storage sa_peer;
-    int       buf;
+    unsigned int buf;
     socklen_t len;
     int       sz, s;
     int	      rc;
@@ -452,7 +452,7 @@ iperf_udp_accept(struct iperf_test *test)
     test->max_fd = (test->max_fd < test->prot_listener) ? test->prot_listener : test->max_fd;
 
     /* Let the client know we're ready "accept" another UDP "stream" */
-    buf = 987654321;		/* any content will work here */
+    buf = UDP_CONNECT_REPLY;
     if (write(s, &buf, sizeof(buf)) < 0) {
         i_errno = IESTREAMWRITE;
         return -1;
@@ -494,11 +494,13 @@ iperf_udp_listen(struct iperf_test *test)
 int
 iperf_udp_connect(struct iperf_test *test)
 {
-    int s, buf, sz;
+    int s, sz;
+    unsigned int buf;
 #ifdef SO_RCVTIMEO
     struct timeval tv;
 #endif
     int rc;
+    int i, max_len_wait_for_reply;
 
     /* Create and bind our local socket. */
     if ((s = netdial(test->settings->domain, Pudp, test->bind_address, test->bind_dev, test->bind_port, test->server_hostname, test->server_port, -1)) < 0) {
@@ -564,17 +566,35 @@ iperf_udp_connect(struct iperf_test *test)
      * Write a datagram to the UDP stream to let the server know we're here.
      * The server learns our address by obtaining its peer's address.
      */
-    buf = 123456789;		/* this can be pretty much anything */
+    buf = UDP_CONNECT_MSG;
+    if (test->debug) {
+        printf("Sending Connect message to Sockt %d\n", s);
+    }
     if (write(s, &buf, sizeof(buf)) < 0) {
         // XXX: Should this be changed to IESTREAMCONNECT?
         i_errno = IESTREAMWRITE;
         return -1;
     }
 
     /*
-     * Wait until the server replies back to us.
+     * Wait until the server replies back to us with the "accept" response.
      */
-    if ((sz = recv(s, &buf, sizeof(buf), 0)) < 0) {
+    i = 0;
+    max_len_wait_for_reply = sizeof(buf);
+    if (test->reverse) /* In reverse mode allow few packets to have the "accept" response - to handle out of order packets */
+        max_len_wait_for_reply += MAX_REVERSE_OUT_OF_ORDER_PACKETS * test->settings->blksize;
+    do {
+        if ((sz = recv(s, &buf, sizeof(buf), 0)) < 0) {
+            i_errno = IESTREAMREAD;
+            return -1;
+        }
+        if (test->debug) {
+            printf("Connect received for Socket %d, sz=%d, buf=%x, i=%d, max_len_wait_for_reply=%d\n", s, sz, buf, i, max_len_wait_for_reply);
+        }
+        i += sz;
+    } while (buf != UDP_CONNECT_REPLY && buf != LEGACY_UDP_CONNECT_REPLY && i < max_len_wait_for_reply);
+
+    if (buf != UDP_CONNECT_REPLY  && buf != LEGACY_UDP_CONNECT_REPLY) {
         i_errno = IESTREAMREAD;
         return -1;
     }