Ticket #13634: tcp-rfc-5681-implemented-ideal-timer.patch

src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp

@@ -1357 +1357 @@
     if ((segment.flags & TCP_FLAG_PUSH) != 0)
         fReceiveQueue.SetPushPointer();
 
+    if (fSendUnacknowledged == fSendMax) {
+        TRACE("data received, resetting ideal timer to: %"
+                B_PRIdBIGTIME, fRetransmitTimeout);
+            gStackModule->set_timer(&fRetransmitTimer, fRetransmitTimeout);
+            T(TimerSet(this, "ideal", fRetransmitTimeout));
+    }
+
     return fReceiveQueue.Available() > 0;
 }
 
@@ -2221 +2228 @@
         }
 
         if (fSendUnacknowledged == fSendMax) {
-            TRACE("all acknowledged, cancelling retransmission timer");
-            gStackModule->cancel_timer(&fRetransmitTimer);
-            T(TimerSet(this, "retransmit", -1));
+            TRACE("all acknowledged, cancelling retransmission timer. Using it as ideal timer for: %"
+                B_PRIdBIGTIME, fRetransmitTimeout);
+            gStackModule->set_timer(&fRetransmitTimer, fRetransmitTimeout);
+            T(TimerSet(this, "ideal", fRetransmitTimeout));
         } else {
             TRACE("data acknowledged, resetting retransmission timer to: %"
                 B_PRIdBIGTIME, fRetransmitTimeout);
@@ -2261 +2269 @@
 void
 TCPEndpoint::_Retransmit()
 {
-    TRACE("Retransmit()");
+    if (fState < ESTABLISHED) {
+        fRetransmitTimeout = TCP_SYN_RETRANSMIT_TIMEOUT;
+        fCongestionWindow = fSendMaxSegmentSize;
+
+    } else if (fSendUnacknowledged == fSendMax) {
+        TRACE("Ideal timeout");
+        // idle period time out - did not receive any segment for a time equal
+        // to the retransmission timeout
+        uint32 initialWindow;
+        if (fSendMaxSegmentSize > 2190)
+            initialWindow = 2 * fSendMaxSegmentSize;
+        else if (fSendMaxSegmentSize > 1095)
+            initialWindow = 3 * fSendMaxSegmentSize;
+        else
+            initialWindow = 4 * fSendMaxSegmentSize;
 
-    _ResetSlowStart();
-    fSendNext = fSendUnacknowledged;
+        fCongestionWindow = min_c(initialWindow, fCongestionWindow);
+        return;
 
-    // Do exponential back off of the retransmit timeout
-    fRetransmitTimeout *= 2;
-    if (fRetransmitTimeout > TCP_MAX_RETRANSMIT_TIMEOUT)
-        fRetransmitTimeout = TCP_MAX_RETRANSMIT_TIMEOUT;
+    } else {
+        _ResetSlowStart();
+
+        // Do exponential back off of the retransmit timeout
+        fRetransmitTimeout *= 2;
+        if (fRetransmitTimeout > TCP_MAX_RETRANSMIT_TIMEOUT)
+            fRetransmitTimeout = TCP_MAX_RETRANSMIT_TIMEOUT;
+    }
 
+    TRACE("Retransmit()");
+
+    fSendNext = fSendUnacknowledged;
     _SendQueued();
 }
 
@@ -2317 +2346 @@
     T(TimerTriggered(endpoint, "retransmit"));
 
     MutexLocker locker(endpoint->fLock);
-    if (!locker.IsLocked())
+    if (!locker.IsLocked() || gStackModule->is_timer_active(timer))
         return;
 
     endpoint->_Retransmit();

src/add-ons/kernel/network/protocols/tcp/tcp.h

@@ -193 +193 @@
 #define TCP_MIN_RETRANSMIT_TIMEOUT      200000      // 200 msecs
 // Maximum retransmit timeout (per RFC6298)
 #define TCP_MAX_RETRANSMIT_TIMEOUT      60000000    // 60 secs
+// New value for timeout in case of lost SYN (RFC 6298)
+#define TCP_SYN_RETRANSMIT_TIMEOUT      3000000     // 3 secs
 
 struct tcp_sack {
     uint32 left_edge;