tcp: Avoid wrap in seq num check, reparse TS if missing

Author: AndreasAakesson

src/net/tcp/connection.cpp

@@ -666,9 +666,11 @@ void Connection::rtx_ack(const seq_t ack) {
 
 void Connection::trigger_window_update(os::mem::Pmr_resource& res)
 {
-  //printf("window freed up? %zu\n", res.allocatable());
-  if(res.allocatable() >= (host_.max_bufsize() * Read_request::buffer_limit))
+  const auto reserve = (host_.max_bufsize() * Read_request::buffer_limit);
+  if(res.allocatable() >= reserve and cb.RCV.WND == 0) {
+    //printf("allocatable=%zu cur_win=%u\n", res.allocatable(), cb.RCV.WND);
     send_window_update();
+  }
 }
 
 uint32_t Connection::calculate_rcv_wnd() const
@@ -799,7 +801,7 @@ void Connection::recv_data(const Packet_view& in)
     }
   }
   // Packet out of order
-  else if((in.seq() - cb.RCV.NXT) < cb.RCV.WND)
+  else if(( (in.seq() + in.tcp_data_length()) - cb.RCV.NXT) < cb.RCV.WND)
   {
     // only accept the data if we have a read request
     if(read_request != nullptr)

src/net/tcp/connection_states.cpp

@@ -94,7 +94,6 @@ using namespace std;
 bool Connection::State::check_seq(Connection& tcp, Packet_view& in)
 {
   auto& tcb = tcp.tcb();
-  uint32_t packet_end = static_cast<uint32_t>(in.seq() + in.tcp_data_length()-1);
 
   // RFC 7323
   static constexpr uint8_t HEADER_WITH_TS{sizeof(Header) + 12};
@@ -127,24 +126,9 @@ bool Connection::State::check_seq(Connection& tcp, Packet_view& in)
     goto unacceptable;
 
   // #2 - Packet is ahead of what we expect to receive, but inside our window
-  if( tcb.RCV.NXT <= in.seq() and in.seq() < tcb.RCV.NXT + tcb.RCV.WND ) {
+  if( (in.seq() - tcb.RCV.NXT) < tcb.RCV.WND ) {
     goto acceptable;
   }
-  // #3 (INVALID) - Packet is outside the right edge of the recv window
-  else if( packet_end > tcb.RCV.NXT+tcb.RCV.WND ) {
-    //printf("Outside right: %s NXT=%u WND=%u\n", in.to_string().c_str(), tcb.RCV.NXT, tcb.RCV.WND);
-    goto unacceptable;
-  }
-  // #4 - Packet with payload is what we expect or bigger, but inside our window
-  else if( tcb.RCV.NXT <= packet_end
-      and packet_end < tcb.RCV.NXT+tcb.RCV.WND ) {
-    goto acceptable;
-  }
-  else
-  {
-    //printf("Probably outside on left side %s end=%u NXT=%u WND=%u\n",
-    //  in.to_string().c_str(), packet_end, tcb.RCV.NXT, tcb.RCV.WND);
-  }
   /*
     If an incoming segment is not acceptable, an acknowledgment
     should be sent in reply (unless the RST bit is set, if so drop
@@ -167,10 +151,13 @@ bool Connection::State::check_seq(Connection& tcp, Packet_view& in)
 
 acceptable:
   const auto* ts = in.ts_option();
+  if(tcb.SND.TS_OK)
+    ts = in.parse_ts_option();
+
   if(ts != nullptr and
-    (ntohl(ts->val) >= tcb.TS_recent and in.seq() <= tcp.last_ack_sent_))
+    (ts->get_val() >= tcb.TS_recent and in.seq() <= tcp.last_ack_sent_))
   {
-    tcb.TS_recent = ntohl(ts->val);
+    tcb.TS_recent = ts->get_val();
   }
   debug2("<Connection::State::check_seq> Acceptable SEQ: %u \n", in.seq());
   // is acceptable.