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Commit f11135a3 authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
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[DCCP]: Dedicated auxiliary states to support passive-close 



This adds two auxiliary states to deal with passive closes:
  * PASSIVE_CLOSE    (reached from OPEN via reception of Close)    and
  * PASSIVE_CLOSEREQ (reached from OPEN via reception of CloseReq)
as internal intermediate states.

These states are used to allow a receiver to process unread data before
acknowledging the received connection-termination-request (the Close/CloseReq).

Without such support, it will happen that passively-closed sockets enter CLOSED
state while there is still unprocessed data in the queue; leading to unexpected
and erratic API behaviour.

PASSIVE_CLOSE has been mapped into TCPF_CLOSE_WAIT, so that the code will
seamlessly work with inet_accept() (which tests for this state).

The state names are thanks to Arnaldo, who suggested this naming scheme
following an earlier revision of this patch.

Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f53dc67c

include/linux/dccp.h

+39 −17
Original line number Diff line number Diff line
@@ -231,14 +231,35 @@ enum dccp_state { 
	DCCP_REQUESTING	     = TCP_SYN_SENT,

	DCCP_LISTEN	     = TCP_LISTEN,

	DCCP_RESPOND	     = TCP_SYN_RECV,

	/*

	 * States involved in closing a DCCP connection:

	 * 1) ACTIVE_CLOSEREQ is entered by a server sending a CloseReq.

	 *

	 * 2) CLOSING can have three different meanings (RFC 4340, 8.3):

	 *  a. Client has performed active-close, has sent a Close to the server

	 *     from state OPEN or PARTOPEN, and is waiting for the final Reset

	 *     (in this case, SOCK_DONE == 1).

	 *  b. Client is asked to perform passive-close, by receiving a CloseReq

	 *     in (PART)OPEN state. It sends a Close and waits for final Reset

	 *     (in this case, SOCK_DONE == 0).

	 *  c. Server performs an active-close as in (a), keeps TIMEWAIT state.

	 *

	 * 3) The following intermediate states are employed to give passively

	 *    closing nodes a chance to process their unread data:

	 *    - PASSIVE_CLOSE    (from OPEN => CLOSED) and

	 *    - PASSIVE_CLOSEREQ (from (PART)OPEN to CLOSING; case (b) above).

	 */

	DCCP_ACTIVE_CLOSEREQ = TCP_FIN_WAIT1,

	DCCP_PASSIVE_CLOSE   = TCP_CLOSE_WAIT,	/* any node receiving a Close */

	DCCP_CLOSING	     = TCP_CLOSING,

	DCCP_TIME_WAIT	     = TCP_TIME_WAIT,

	DCCP_CLOSED	     = TCP_CLOSE,

	DCCP_PARTOPEN	     = TCP_MAX_STATES,

	DCCP_PASSIVE_CLOSEREQ,			/* clients receiving CloseReq */

	DCCP_MAX_STATES

};



#define DCCP_STATE_MASK 0xf

#define DCCP_STATE_MASK 0x1f

#define DCCP_ACTION_FIN (1<<7)



enum {
@@ -246,10 +267,11 @@ enum { 
	DCCPF_REQUESTING      = TCPF_SYN_SENT,

	DCCPF_LISTEN	      = TCPF_LISTEN,

	DCCPF_RESPOND	      = TCPF_SYN_RECV,

	DCCPF_ACTIVE_CLOSEREQ = TCPF_FIN_WAIT1,

	DCCPF_CLOSING	      = TCPF_CLOSING,

	DCCPF_TIME_WAIT	      = TCPF_TIME_WAIT,

	DCCPF_CLOSED	      = TCPF_CLOSE,

	DCCPF_PARTOPEN	 = 1 << DCCP_PARTOPEN,

	DCCPF_PARTOPEN	      = (1 << DCCP_PARTOPEN),

};



static inline struct dccp_hdr *dccp_hdr(const struct sk_buff *skb)

net/dccp/proto.c

+12 −10
Original line number Diff line number Diff line
@@ -60,8 +60,7 @@ void dccp_set_state(struct sock *sk, const int state) 
{

	const int oldstate = sk->sk_state;



	dccp_pr_debug("%s(%p) %-10.10s -> %s\n",

		      dccp_role(sk), sk,

	dccp_pr_debug("%s(%p)  %s  -->  %s\n", dccp_role(sk), sk,

		      dccp_state_name(oldstate), dccp_state_name(state));

	WARN_ON(state == oldstate);
@@ -140,6 +139,9 @@ const char *dccp_state_name(const int state) 
	[DCCP_LISTEN]		= "LISTEN",

	[DCCP_RESPOND]		= "RESPOND",

	[DCCP_CLOSING]		= "CLOSING",

	[DCCP_ACTIVE_CLOSEREQ]	= "CLOSEREQ",

	[DCCP_PASSIVE_CLOSE]	= "PASSIVE_CLOSE",

	[DCCP_PASSIVE_CLOSEREQ]	= "PASSIVE_CLOSEREQ",

	[DCCP_TIME_WAIT]	= "TIME_WAIT",

	[DCCP_CLOSED]		= "CLOSED",

	};