Date: Sun, 19 Mar 2017 18:49:16 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-net@FreeBSD.org Subject: [Bug 217637] One TCP connection accepted TWO times Message-ID: <bug-217637-2472-s5SCLgDELZ@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-217637-2472@https.bugs.freebsd.org/bugzilla/> References: <bug-217637-2472@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D217637 --- Comment #36 from slw@zxy.spb.ru --- (In reply to Michael Tuexen from comment #35) > This doesn't happen because NEW data arrives and the application has call= ed close(). So this new data cannot be delivered to the application. The TCP stack has = do drop it. That is why a RST is sent and the connection is moved to CLOSED. I mean in this case RST must send in sequence, w/ ACK set and ACKed recv da= ta. And don't moved to CLOSED. RFC793: " 3.5. Closing a Connection CLOSE is an operation meaning "I have no more data to send." The notion of closing a full-duplex connection is subject to ambiguous interpretation, of course, since it may not be obvious how to treat the receiving side of the connection. We have chosen to treat CLOSE in a simplex fashion. The user who CLOSEs may continue to RECEIVE until he is told that the other side has CLOSED also. Thus, a program could initiate several SENDs followed by a CLOSE, and then continue to RECEIVE until signaled that a RECEIVE failed because the other side has CLOSED. We assume that the TCP will signal a user, even if no RECEIVEs are outstanding, that the other side has closed, so the user can terminate his side gracefully. A TCP will reliably deliver all buffers SENT before the connection was CLOSED so a user who expects no data in return need only wait to hear the connection was CLOSED successfully to know that all his data was received at the destination TCP. Users must keep reading connections they close for sending until the TCP says no more data. Case 1: Local user initiates the close In this case, a FIN segment can be constructed and placed on the outgoing segment queue. No further SENDs from the user will be accepted by the TCP, and it enters the FIN-WAIT-1 state. RECEIVEs are allowed in this state. All segments preceding and including FIN will be retransmitted until acknowledged. When the other TCP has both acknowledged the FIN and sent a FIN of its own, the first TCP can ACK this FIN. Note that a TCP receiving a FIN will ACK but not send its own FIN until its user has CLOSED the connection also. " --=20 You are receiving this mail because: You are the assignee for the bug.=
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