tcp_input: if tcp->req > recvreq, send ack only when state is TCP_EST…

…ABLISHED

The Bluetooth network on N62 does not retransmit packet, so no packet
retransmition if we drop one, we will drop packet when tcp_close_eventhandler
is register and invoke by tcp_input. then we will always early return and
never stop, the peer will only close the connection if we send reset packet.

precondition:
close -> register tcp_close_eventhandler;

tcp_input -> tcp_callback(TCP_NEWDATA) -> devif_conn_event -> tcp_close_eventhandler
-> flags &= ~TCP_NEWDATA -> NOT entry tcp_data_event -> conn->recvreq NOT increase

old flow:
tcp_input -> tcp->seqno greater than conn->rcvseq -> tcp_send(TCP_ACK)

with this patch:
tcp_input -> tcp->seqno greater than conn->rcvseq -> !TCP_ESTABLISHED
-> case TCP_FIN_WAIT_1 -> dev->d_len greater than 0 -> tcp_reset

Signed-off-by: zhanghongyu <[email protected]>

net/tcp/tcp_input.c

@@ -1185,8 +1185,11 @@ static void tcp_input(FAR struct net_driver_s *dev, uint8_t domain,
 
               tcp_input_ofosegs(dev, conn, iplen);
 #endif
-              tcp_send(dev, conn, TCP_ACK, tcpiplen);
-              return;
+              if ((conn->tcpstateflags & TCP_STATE_MASK) <= TCP_ESTABLISHED)
+                {
+                  tcp_send(dev, conn, TCP_ACK, tcpiplen);
+                  return;
+                }
             }
         }
     }