tcp: Fixed SND ack comparison

Author: KristianJerpetjon

src/net/tcp/connection.cpp

@@ -170,6 +170,22 @@ void Connection::offer(size_t& packets)
 
   // write until we either cant send more (window closes or no more in queue),
   // or we're out of packets.
+
+  static bool congested=false;
+  if (!can_send())
+  {
+    if (sendq_remaining() > 0)
+    {
+      printf("Window_blocked %d data %zu empty packets sw=%ld fs=%ld WND=%d\n",sendq_remaining(),packets,(int64_t)send_window(), (int64_t)flight_size(),cb.SND.WND);
+      congested=true;
+    }
+  }
+  if (can_send() && congested)
+  {
+    printf("Window released congestion removed %zu packets\n",packets);
+    congested=false;
+  }
+
   while(can_send() and packets)
   {
     auto packet = create_outgoing_packet();
@@ -397,49 +413,44 @@ bool Connection::handle_ack(const Packet_view& in)
   } // < dup ack
 
   // new ack
-  else if(LIKELY(in.ack() >= cb.SND.UNA))
-  {
-    if(is_win_update(in, true_win))
-    {
-      cb.SND.WND = true_win;
-      cb.SND.WL1 = in.seq();
-      cb.SND.WL2 = in.ack();
-      //printf("<Connection::handle_ack> Window update (%u)\n", cb.SND.WND);
-    }
-    //pred_flags = htonl((in.tcp_header_length() << 26) | 0x10 | cb.SND.WND >> cb.SND.wind_shift);
-
-    // [RFC 6582] p. 8
-    prev_highest_ack_ = cb.SND.UNA;
-    highest_ack_ = in.ack();
 
-    if(cb.SND.TS_OK)
-    {
-      const auto* ts = in.ts_option();
-      if(ts != nullptr) // TODO: not sure the packet is valid if TS missing
-        last_acked_ts_ = ts->ecr;
-    }
+  if(is_win_update(in, true_win))
+  {
+    cb.SND.WND = true_win;
+    cb.SND.WL1 = in.seq();
+    cb.SND.WL2 = in.ack();
+    //printf("<Connection::handle_ack> Window update (%u)\n", cb.SND.WND);
+  }
+  //pred_flags = htonl((in.tcp_header_length() << 26) | 0x10 | cb.SND.WND >> cb.SND.wind_shift);
 
-    cb.SND.UNA = in.ack();
+  // [RFC 6582] p. 8
+  prev_highest_ack_ = cb.SND.UNA;
+  highest_ack_ = in.ack();
 
-    rtx_ack(in.ack());
+  if(cb.SND.TS_OK)
+  {
+    const auto* ts = in.ts_option();
+    if(ts != nullptr) // TODO: not sure the packet is valid if TS missing
+      last_acked_ts_ = ts->ecr;
+  }
 
-    take_rtt_measure(in);
+  cb.SND.UNA = in.ack();
 
-    // do either congctrl or fastrecov according to New Reno
-    (not fast_recovery_)
-      ? congestion_control(in) : fast_recovery(in);
+  rtx_ack(in.ack());
 
-    dup_acks_ = 0;
+  take_rtt_measure(in);
 
-    if(in.has_tcp_data() or in.isset(FIN))
-      return true;
+  // do either congctrl or fastrecov according to New Reno
+  (not fast_recovery_)
+    ? congestion_control(in) : fast_recovery(in);
 
-  } // < new ack
+  dup_acks_ = 0;
 
-  // ACK outside
-  else {
+  if(in.has_tcp_data() or in.isset(FIN))
     return true;
-  }
+
+  // < new ack
+  // Nothing to process
   return false;
 }
 

src/net/tcp/connection_states.cpp

@@ -240,17 +240,10 @@ bool Connection::State::check_ack(Connection& tcp, const Packet_view& in) {
     // Correction: [RFC 1122 p. 94]
     // ACK is inside sequence space
     //return tcp.handle_ack(in);
-    if(in.ack() <= tcb.SND.NXT ) {
+
+    if ( (in.ack()-tcb.SND.UNA) <= (tcb.SND.NXT-tcb.SND.UNA)) {
 
       return tcp.handle_ack(in);
-      // this is a "new" ACK
-      //if(tcb.SND.UNA <= in->ack()) {
-
-        // this is a NEW ACK
-        //if(tcb.SND.UNA < in->ack())
-        //{
-        //  tcp.acknowledge(in->ack());
-        //}
          // [RFC 5681]
         /*
           DUPLICATE ACKNOWLEDGMENT:
@@ -268,23 +261,7 @@ bool Connection::State::check_ack(Connection& tcp, const Packet_view& in) {
           new data unless the incoming duplicate acknowledgment contains
           new SACK information.
         */
-        // this is a RFC 5681 DUP ACK
-        //!in->isset(FIN) and !in->isset(SYN)
-        //else if(tcp.reno_is_dup_ack(in)) {
-        //  debug2("<Connection::State::check_ack> Reno Dup ACK %u\n", in->ack());
-        //  tcp.reno_dup_ack(in->ack());
-        //}
-        // this is an RFC 793 DUP ACK
-        //else {
-          //printf("<Connection::State::check_ack> RFC 793 Dup ACK %u\n", in->ack());
-        //}
-      //}
-      // this is an "old" ACK out of order
-      //else {
-      //  printf("<Connection::State::check_ack> ACK out of order (SND.UNA > ACK)\n");
-      //}
-      // tcp.signal_sent();
-      // return that buffer has been SENT - currently no support to receipt sent buffer.
+
     }
     /* If the ACK acks something not yet sent (SEG.ACK > SND.NXT) then send an ACK, drop the segment, and return. */
     else {