[lwip-devel] [bug #26251] RST process in TIME_WAIT TCP state

[Simon Goldschmidt]

Update of bug #26251 (project lwip):

                  Status:                   Fixed => In Progress            
             Open/Closed:                  Closed => Open                   

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Follow-up Comment #12:

I'd rather make it

if (((flags & (TCP_RST | TCP_SYN)) == 0) && (tcplen > 0))  {

because I thought ACKing SYNs in TIME_WAIT wasn't OK. RFC 793 says we shall
sent a RST if the SYN is in the window and go to CLOSED. However that's what
RFC 1337 wants to avoid so I'd ignore the SYN (or should we send a RST and
stay in TIME_WAIT?). A SYN is outside the window wouldn't happen in this
state... so I'd ignore it, too.

See this excerpt from RFC 793, page 70:

>>> snip >>>
fourth, check the SYN bit,

      SYN-RECEIVED
      ESTABLISHED STATE
      FIN-WAIT STATE-1
      FIN-WAIT STATE-2
      CLOSE-WAIT STATE
      CLOSING STATE
      LAST-ACK STATE
      TIME-WAIT STATE

        If the SYN is in the window it is an error, send a reset, any
        outstanding RECEIVEs and SEND should receive "reset" responses,
        all segment queues should be flushed, the user should also
        receive an unsolicited general "connection reset" signal, enter
        the CLOSED state, delete the TCB, and return.

        If the SYN is not in the window this step would not be reached
        and an ack would have been sent in the first step (sequence
        number check).
<<< snap <<<


(BTW: I don't see anything regarding SYN in TIME-WAIT on page 71 ??)

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