[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: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index a007326..8b3f9ad 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -227,29 +227,51 @@
#include <net/tcp_states.h>
enum dccp_state {
- DCCP_OPEN = TCP_ESTABLISHED,
- DCCP_REQUESTING = TCP_SYN_SENT,
- DCCP_LISTEN = TCP_LISTEN,
- DCCP_RESPOND = TCP_SYN_RECV,
- DCCP_CLOSING = TCP_CLOSING,
- DCCP_TIME_WAIT = TCP_TIME_WAIT,
- DCCP_CLOSED = TCP_CLOSE,
- DCCP_PARTOPEN = TCP_MAX_STATES,
+ DCCP_OPEN = TCP_ESTABLISHED,
+ 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 {
- DCCPF_OPEN = TCPF_ESTABLISHED,
- DCCPF_REQUESTING = TCPF_SYN_SENT,
- DCCPF_LISTEN = TCPF_LISTEN,
- DCCPF_RESPOND = TCPF_SYN_RECV,
- DCCPF_CLOSING = TCPF_CLOSING,
- DCCPF_TIME_WAIT = TCPF_TIME_WAIT,
- DCCPF_CLOSED = TCPF_CLOSE,
- DCCPF_PARTOPEN = 1 << DCCP_PARTOPEN,
+ DCCPF_OPEN = TCPF_ESTABLISHED,
+ 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),
};
static inline struct dccp_hdr *dccp_hdr(const struct sk_buff *skb)