src/transports/utils/cstream.c - third_party/nanomsg - Git at Google

 /*
     Copyright (c) 2012-2013 250bpm s.r.o.

     Permission is hereby granted, free of charge, to any person obtaining a copy
     of this software and associated documentation files (the "Software"),
     to deal in the Software without restriction, including without limitation
     the rights to use, copy, modify, merge, publish, distribute, sublicense,
     and/or sell copies of the Software, and to permit persons to whom
     the Software is furnished to do so, subject to the following conditions:

     The above copyright notice and this permission notice shall be included
     in all copies or substantial portions of the Software.

     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
     THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
     IN THE SOFTWARE.
 */

 #include "cstream.h"

 #include "../../utils/err.h"
 #include "../../utils/cont.h"
 #include "../../utils/addr.h"
 #include "../../utils/alloc.h"
 #include "../../utils/random.h"

 #include <string.h>

 #define NN_CSTREAM_STATE_INIT 1
 #define NN_CSTREAM_STATE_WAITING 2
 #define NN_CSTREAM_STATE_FINISHING_WAITING 3
 #define NN_CSTREAM_STATE_CONNECTING 4
 #define NN_CSTREAM_STATE_CONNECTED 5
 #define NN_CSTREAM_STATE_CLOSING_TIMER 6
 #define NN_CSTREAM_STATE_CLOSING_USOCK 7
 #define NN_CSTREAM_STATE_CLOSED 8

 #define NN_CSTREAM_EVENT_START 1
 #define NN_CSTREAM_EVENT_CLOSE 1

 /*  Private functions. */
 static void nn_cstream_callback (struct nn_fsm *fsm, void *source, int type);
 static int nn_cstream_compute_retry_ivl (struct nn_cstream *self);

 /*  Implementation of nn_epbase interface. */
 static int nn_cstream_close (struct nn_epbase *self);
 static const struct nn_epbase_vfptr nn_cstream_epbase_vfptr =
     {nn_cstream_close};

 int nn_cstream_init (struct nn_cstream *self, const char *addr, void *hint,
     const struct nn_cstream_vfptr *vfptr)
 {
     int rc;
     int sndbuf;
     int rcvbuf;
     size_t sz;

     self->vfptr = vfptr;

     /*  Initialise the 'endpoint' base class. */
     nn_epbase_init (&self->epbase, &nn_cstream_epbase_vfptr, addr, hint);

     /*  Initialise the state machine. */
     nn_fsm_init_root (&self->fsm, nn_cstream_callback,
         nn_epbase_getctx (&self->epbase));
     self->state = NN_CSTREAM_STATE_INIT;

     /*  TODO: Check the syntax of the address and return error if it is
         not a valid address string. Don't do any blocking DNS operations
         though! */

     /*  Open a socket. */
     rc = self->vfptr->open (&self->usock, &self->fsm);
     errnum_assert (rc == 0, -rc);

     /*  Apply current values of NN_SNDBUF and NN_RCVBUF options. */
     sz = sizeof (sndbuf);
     nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_SNDBUF, &sndbuf, &sz);
     nn_assert (sz == sizeof (sndbuf));
     rc = nn_usock_setsockopt (&self->usock, SOL_SOCKET, SO_SNDBUF, &sndbuf, sz);
     errnum_assert (rc == 0, -rc);
     sz = sizeof (rcvbuf);
     nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_RCVBUF, &rcvbuf, &sz);
     nn_assert (sz == sizeof (rcvbuf));
     rc = nn_usock_setsockopt (&self->usock, SOL_SOCKET, SO_RCVBUF, &rcvbuf, sz);
     errnum_assert (rc == 0, -rc);

     /*  Initialise the retry timer. */
     self->retry_ivl = -1;
     nn_timer_init (&self->retry_timer, &self->fsm);

     /*  Start the state machine. */
     nn_cstream_callback (&self->fsm, NULL, NN_CSTREAM_EVENT_START);

     return 0;
 }

 void nn_cstream_term (struct nn_cstream *self)
 {
     nn_assert (0);
 }

 static void nn_cstream_callback (struct nn_fsm *fsm, void *source, int type)
 {
     int rc;
     struct nn_cstream *cstream;
     struct sockaddr_storage local;
     socklen_t locallen;
     struct sockaddr_storage remote;
     socklen_t remotelen;

     cstream = nn_cont (fsm, struct nn_cstream, fsm);

     switch (cstream->state) {
 /******************************************************************************/
 /*  INIT state.                                                               */
 /******************************************************************************/
     case NN_CSTREAM_STATE_INIT:
         if (source == NULL) {
             switch (type) {
             case NN_CSTREAM_EVENT_START:

                 /* Try to resolve the address. */
                 rc = cstream->vfptr->resolve (
                     nn_epbase_getaddr (&cstream->epbase),
                     &local, &locallen, &remote, &remotelen);

                 /* If the address resolution have failed, wait before
                    re-trying. */
                 if (rc < 0) {
                     nn_timer_start (&cstream->retry_timer,
                         nn_cstream_compute_retry_ivl (cstream));
                     cstream->state = NN_CSTREAM_STATE_WAITING;
                     return;
                 }

                 /*  Start connecting. */
                 if (rc & NN_CSTREAM_DOBIND)
                     nn_usock_bind (&cstream->usock,
                         (struct sockaddr*) &local, locallen);
                 nn_usock_connect (&cstream->usock,
                     (struct sockaddr*) &remote, remotelen);
                 cstream->state = NN_CSTREAM_STATE_CONNECTING;
                 return;
             default:
                 nn_assert (0);
             }
         }
         nn_assert (0);
 /******************************************************************************/
 /*  WAITING state.                                                            */
 /******************************************************************************/
     case NN_CSTREAM_STATE_WAITING:
         if (source == &cstream->retry_timer) {
             switch (type) {
             case NN_TIMER_TIMEOUT:
                 nn_assert (0);
             default:
                 nn_assert (0);
             }
         }
         if (source == NULL) {
             switch (type) {
             case NN_CSTREAM_EVENT_CLOSE:

                 /*  User is closing the object while waiting for reconnection.
                     Cancel the timer and proceed with shutdown. */
                 nn_timer_close (&cstream->retry_timer);
                 cstream->state = NN_CSTREAM_STATE_CLOSING_TIMER;

                 return;
             default:
                 nn_assert (0);
             }
         }
         nn_assert (0);
 /******************************************************************************/
 /*  FINISHING_WAITING state.                                                  */
 /******************************************************************************/
     case NN_CSTREAM_STATE_FINISHING_WAITING:
         nn_assert (0);
 /******************************************************************************/
 /*  CONNECTING state.                                                         */
 /******************************************************************************/
     case NN_CSTREAM_STATE_CONNECTING:
         if (source == &cstream->usock) {
             switch (type) {
             case NN_USOCK_CONNECTED:
                 nn_assert (0);
             case NN_USOCK_ERROR:

                 /* Connecting failed. Wait a while before re-connecting. */
                 nn_timer_start (&cstream->retry_timer,
                     nn_cstream_compute_retry_ivl (cstream));
                 cstream->state = NN_CSTREAM_STATE_WAITING;

                 return;
             default:
                 nn_assert (0);
             }
         }
         nn_assert (0);
 /******************************************************************************/
 /*  CONNECTED state.                                                          */
 /******************************************************************************/
     case NN_CSTREAM_STATE_CONNECTED:
         nn_assert (0);
 /******************************************************************************/
 /*  CLOSING_TIMER state.                                                      */
 /******************************************************************************/
     case NN_CSTREAM_STATE_CLOSING_TIMER:
         if (source == &cstream->retry_timer) {
             switch (type) {
             case NN_TIMER_CLOSED:
                 nn_usock_close (&cstream->usock);
                 cstream->state = NN_CSTREAM_STATE_CLOSING_USOCK;
                 return;
             default:
                 nn_assert (0);
             }
         }
         nn_assert (0);
 /******************************************************************************/
 /*  CLOSING_USOCK state.                                                      */
 /******************************************************************************/
     case NN_CSTREAM_STATE_CLOSING_USOCK:
         if (source == &cstream->usock) {
             switch (type) {
             case NN_USOCK_CLOSED:
                 cstream->state = NN_CSTREAM_STATE_CLOSED;

                 nn_assert (0);
                 return;
             default:
                 nn_assert (0);
             }
         }
         nn_assert (0);
 /******************************************************************************/
 /*  CLOSED state.                                                             */
 /******************************************************************************/
     case NN_CSTREAM_STATE_CLOSED:
         nn_assert (0);
     default:
         nn_assert (0);
     }
 }

 static int nn_cstream_close (struct nn_epbase *self)
 {
     struct nn_cstream *cstream;

     cstream = nn_cont (self, struct nn_cstream, epbase);

     /*  Pass the event to the state machine. */
     nn_cstream_callback (&cstream->fsm, NULL, NN_CSTREAM_EVENT_CLOSE);
 }

 static int nn_cstream_compute_retry_ivl (struct nn_cstream *self)
 {
     int reconnect_ivl;
     int reconnect_ivl_max;
     size_t sz;
     int result;
     unsigned int random;

     /*  Get relevant options' values. */
     sz = sizeof (reconnect_ivl);
     nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_RECONNECT_IVL,
         &reconnect_ivl, &sz);
     nn_assert (sz == sizeof (reconnect_ivl));
     sz = sizeof (reconnect_ivl_max);
     nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_RECONNECT_IVL_MAX,
         &reconnect_ivl_max, &sz);
     nn_assert (sz == sizeof (reconnect_ivl_max));

     /*  Negative number means that reconnect sequence is starting.
         The reconnect interval in this case is NN_RECONNECT_IVL. */
     if (self->retry_ivl < 0)
         self->retry_ivl = reconnect_ivl;

     /*  Current retry_ivl will be returned to the caller. */
     result = self->retry_ivl;

     /*  Re-compute new retry interval. */
     if (reconnect_ivl_max > 0 && reconnect_ivl_max > reconnect_ivl) {
         self->retry_ivl *= 2;
         if (self->retry_ivl > reconnect_ivl_max)
             self->retry_ivl = reconnect_ivl_max;
     }

     /*  Randomise the result to prevent re-connection storms when network
         and/or server goes down and then up again. This may rise
         the reconnection interval at most twice and at most by one second. */
     nn_random_generate (&random, sizeof (random));
     result += (random % result % 1000);
     return result;
 }

 #if 0

 /*  Private functions. */
 static int nn_cstream_compute_retry_ivl (struct nn_cstream *self);

 int nn_cstream_init (struct nn_cstream *self, const char *addr, void *hint,
     int (*initsockfn) (struct nn_usock *sock, int sndbuf, int rcvbuf),
     int (*resolvefn) (const char *addr,
     struct sockaddr_storage *local, socklen_t *locallen,
     struct sockaddr_storage *remote, socklen_t *remotelen))
 {
     nn_assert (0);
 }

 #if 0
 /******************************************************************************/
 /*  State: WAITING                                                            */
 /******************************************************************************/

 static void nn_cstream_waiting_timeout (const struct nn_cp_sink **self,
     struct nn_aio_timer *timer);
 static const struct nn_cp_sink nn_cstream_state_waiting = {
     NULL,
     NULL,
     NULL,
     NULL,
     NULL,
     NULL,
     nn_cstream_waiting_timeout,
     NULL
 };

 static void nn_cstream_waiting_timeout (const struct nn_cp_sink **self,
     struct nn_aio_timer *timer)
 {
     int rc;
     struct nn_cstream *cstream;
     struct sockaddr_storage local;
     socklen_t locallen;
     struct sockaddr_storage remote;
     socklen_t remotelen;

     cstream = nn_cont (self, struct nn_cstream, sink);

     /*  Retry timer expired. Now we'll try to resolve the address. */
     rc = cstream->resolvefn (nn_epbase_getaddr (&cstream->epbase),
         &local, &locallen, &remote, &remotelen);

     /*  If the address resolution have failed, wait and re-try. */
     if (rc < 0) {
         cstream->sink = &nn_cstream_state_waiting;
         nn_aio_timer_start (&cstream->retry_timer,
             nn_cstream_compute_retry_ivl (cstream));
         return;
     }

     /*  Open the socket and start connecting. */
     cstream->sink = &nn_cstream_state_connecting;
     if (rc & NN_CSTREAM_DOBIND)
         nn_aio_usock_bind (&cstream->usock,
             (struct sockaddr*) &local, locallen);
     nn_aio_usock_connect (&cstream->usock,
         (struct sockaddr*) &remote, remotelen);
 }

 /******************************************************************************/
 /*  State: CONNECTING                                                         */
 /******************************************************************************/

 static void nn_cstream_connecting_connected (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock);
 static void nn_cstream_connecting_err (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock, int errnum);
 static const struct nn_cp_sink nn_cstream_state_connecting = {
     NULL,
     NULL,
     nn_cstream_connecting_connected,
     NULL,
     nn_cstream_connecting_err,
     NULL,
     NULL,
     NULL
 };

 static void nn_cstream_connecting_connected (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock)
 {
     struct nn_cstream *cstream;

     cstream = nn_cont (self, struct nn_cstream, sink);

     /*  TODO: Set current reconnect interval to the value of
         NN_RECONNECT_IVL. */

     /*  Connect succeeded. Switch to the session state machine. */
     cstream->sink = &nn_cstream_state_connected;
     nn_stream_init (&cstream->stream, &cstream->epbase, &cstream->usock);
 }

 static void nn_cstream_connecting_err (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock, int errnum)
 {
     struct nn_cstream *cstream;

     cstream = nn_cont (self, struct nn_cstream, sink);

     /*  Connect failed. Close the underlying socket. */
     cstream->sink = &nn_cstream_state_closing;
     nn_aio_usock_close (&cstream->usock);
 }

 /******************************************************************************/
 /*  State: CONNECTED                                                          */
 /******************************************************************************/

 /*  In this state control is yielded to the 'stream' state machine. */

 static void nn_cstream_connected_err (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock, int errnum);
 static const struct nn_cp_sink nn_cstream_state_connected = {
     NULL,
     NULL,
     NULL,
     NULL,
     nn_cstream_connected_err,
     NULL,
     NULL,
     NULL
 };

 static void nn_cstream_connected_err (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock, int errnum)
 {
     struct nn_cstream *cstream;

     cstream = nn_cont (self, struct nn_cstream, sink);

     /*  The connection is broken. Reconnect. */
     cstream->sink = &nn_cstream_state_waiting;
     nn_cstream_waiting_timeout (&cstream->sink, &cstream->retry_timer);
 }

 /******************************************************************************/
 /*  State: CLOSING                                                            */
 /******************************************************************************/

 static void nn_cstream_closing_closed (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock);
 static const struct nn_cp_sink nn_cstream_state_closing = {
     NULL,
     NULL,
     NULL,
     NULL,
     NULL,
     nn_cstream_closing_closed,
     NULL,
     NULL
 };

 static void nn_cstream_closing_closed (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock)
 {
     int rc;
     struct nn_cstream *cstream;
     int sndbuf;
     int rcvbuf;
     size_t sz;

     cstream = nn_cont (self, struct nn_cstream, sink);

     /*  Get the current values of NN_SNDBUF and NN_RCVBUF options. */
     sz = sizeof (sndbuf);
     nn_epbase_getopt (&cstream->epbase, NN_SOL_SOCKET, NN_SNDBUF, &sndbuf, &sz);
     nn_assert (sz == sizeof (sndbuf));
     sz = sizeof (rcvbuf);
     nn_epbase_getopt (&cstream->epbase, NN_SOL_SOCKET, NN_RCVBUF, &rcvbuf, &sz);
     nn_assert (sz == sizeof (rcvbuf));

     /*  Create new socket. */
     rc = cstream->initsockfn (&cstream->usock, sndbuf, rcvbuf,
         nn_epbase_getcp (&cstream->epbase));
     errnum_assert (rc == 0, -rc);
     nn_aio_usock_setsink (&cstream->usock, &cstream->sink);

     /*  Wait for the specified period. */
     cstream->sink = &nn_cstream_state_waiting;
     nn_aio_timer_start (&cstream->retry_timer,
         nn_cstream_compute_retry_ivl (cstream));
 }

 /******************************************************************************/
 /*  State: TERMINATING                                                        */
 /******************************************************************************/

 static void nn_cstream_terminating_closed (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock);
 static const struct nn_cp_sink nn_cstream_state_terminating = {
     NULL,
     NULL,
     NULL,
     NULL,
     NULL,
     nn_cstream_terminating_closed,
     NULL,
     NULL
 };

 static int nn_cstream_close (struct nn_epbase *self)
 {
     struct nn_cstream *cstream;

     cstream = nn_cont (self, struct nn_cstream, epbase);

     /*  If termination is already underway, do nothing and let it continue. */
     if (cstream->sink == &nn_cstream_state_terminating)
         return -EINPROGRESS;

     /*  If the connection exists, stop the session state machine. */
     if (cstream->sink == &nn_cstream_state_connected)
         nn_stream_term (&cstream->stream);

     /*  Deallocate resources. */
     nn_aio_timer_term (&cstream->retry_timer);

     /*  Close the socket, if needed. */
     cstream->sink = &nn_cstream_state_terminating;
     nn_aio_usock_close (&cstream->usock);

     return -EINPROGRESS;
 }

 static void nn_cstream_terminating_closed (const struct nn_cp_sink **self,
     struct nn_aio_usock *usock)
 {
     struct nn_cstream *cstream;

     cstream = nn_cont (self, struct nn_cstream, sink);

     nn_epbase_term (&cstream->epbase);
     nn_free (cstream);
 }

 #endif

 #endif
	/*
	Copyright (c) 2012-2013 250bpm s.r.o.

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"),
	to deal in the Software without restriction, including without limitation
	the rights to use, copy, modify, merge, publish, distribute, sublicense,
	and/or sell copies of the Software, and to permit persons to whom
	the Software is furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included
	in all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	IN THE SOFTWARE.
	*/

	#include "cstream.h"

	#include "../../utils/err.h"
	#include "../../utils/cont.h"
	#include "../../utils/addr.h"
	#include "../../utils/alloc.h"
	#include "../../utils/random.h"

	#include <string.h>

	#define NN_CSTREAM_STATE_INIT 1
	#define NN_CSTREAM_STATE_WAITING 2
	#define NN_CSTREAM_STATE_FINISHING_WAITING 3
	#define NN_CSTREAM_STATE_CONNECTING 4
	#define NN_CSTREAM_STATE_CONNECTED 5
	#define NN_CSTREAM_STATE_CLOSING_TIMER 6
	#define NN_CSTREAM_STATE_CLOSING_USOCK 7
	#define NN_CSTREAM_STATE_CLOSED 8

	#define NN_CSTREAM_EVENT_START 1
	#define NN_CSTREAM_EVENT_CLOSE 1

	/* Private functions. */
	static void nn_cstream_callback (struct nn_fsm fsm, void source, int type);
	static int nn_cstream_compute_retry_ivl (struct nn_cstream *self);

	/* Implementation of nn_epbase interface. */
	static int nn_cstream_close (struct nn_epbase *self);
	static const struct nn_epbase_vfptr nn_cstream_epbase_vfptr =
	{nn_cstream_close};

	int nn_cstream_init (struct nn_cstream self, const char addr, void *hint,
	const struct nn_cstream_vfptr *vfptr)
	{
	int rc;
	int sndbuf;
	int rcvbuf;
	size_t sz;

	self->vfptr = vfptr;

	/* Initialise the 'endpoint' base class. */
	nn_epbase_init (&self->epbase, &nn_cstream_epbase_vfptr, addr, hint);

	/* Initialise the state machine. */
	nn_fsm_init_root (&self->fsm, nn_cstream_callback,
	nn_epbase_getctx (&self->epbase));
	self->state = NN_CSTREAM_STATE_INIT;

	/* TODO: Check the syntax of the address and return error if it is
	not a valid address string. Don't do any blocking DNS operations
	though! */

	/* Open a socket. */
	rc = self->vfptr->open (&self->usock, &self->fsm);
	errnum_assert (rc == 0, -rc);

	/* Apply current values of NN_SNDBUF and NN_RCVBUF options. */
	sz = sizeof (sndbuf);
	nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_SNDBUF, &sndbuf, &sz);
	nn_assert (sz == sizeof (sndbuf));
	rc = nn_usock_setsockopt (&self->usock, SOL_SOCKET, SO_SNDBUF, &sndbuf, sz);
	errnum_assert (rc == 0, -rc);
	sz = sizeof (rcvbuf);
	nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_RCVBUF, &rcvbuf, &sz);
	nn_assert (sz == sizeof (rcvbuf));
	rc = nn_usock_setsockopt (&self->usock, SOL_SOCKET, SO_RCVBUF, &rcvbuf, sz);
	errnum_assert (rc == 0, -rc);

	/* Initialise the retry timer. */
	self->retry_ivl = -1;
	nn_timer_init (&self->retry_timer, &self->fsm);

	/* Start the state machine. */
	nn_cstream_callback (&self->fsm, NULL, NN_CSTREAM_EVENT_START);

	return 0;
	}

	void nn_cstream_term (struct nn_cstream *self)
	{
	nn_assert (0);
	}

	static void nn_cstream_callback (struct nn_fsm fsm, void source, int type)
	{
	int rc;
	struct nn_cstream *cstream;
	struct sockaddr_storage local;
	socklen_t locallen;
	struct sockaddr_storage remote;
	socklen_t remotelen;

	cstream = nn_cont (fsm, struct nn_cstream, fsm);

	switch (cstream->state) {
	/******************************************************************************/
	/* INIT state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_INIT:
	if (source == NULL) {
	switch (type) {
	case NN_CSTREAM_EVENT_START:

	/* Try to resolve the address. */
	rc = cstream->vfptr->resolve (
	nn_epbase_getaddr (&cstream->epbase),
	&local, &locallen, &remote, &remotelen);

	/* If the address resolution have failed, wait before
	re-trying. */
	if (rc < 0) {
	nn_timer_start (&cstream->retry_timer,
	nn_cstream_compute_retry_ivl (cstream));
	cstream->state = NN_CSTREAM_STATE_WAITING;
	return;
	}

	/* Start connecting. */
	if (rc & NN_CSTREAM_DOBIND)
	nn_usock_bind (&cstream->usock,
	(struct sockaddr*) &local, locallen);
	nn_usock_connect (&cstream->usock,
	(struct sockaddr*) &remote, remotelen);
	cstream->state = NN_CSTREAM_STATE_CONNECTING;
	return;
	default:
	nn_assert (0);
	}
	}
	nn_assert (0);
	/******************************************************************************/
	/* WAITING state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_WAITING:
	if (source == &cstream->retry_timer) {
	switch (type) {
	case NN_TIMER_TIMEOUT:
	nn_assert (0);
	default:
	nn_assert (0);
	}
	}
	if (source == NULL) {
	switch (type) {
	case NN_CSTREAM_EVENT_CLOSE:

	/* User is closing the object while waiting for reconnection.
	Cancel the timer and proceed with shutdown. */
	nn_timer_close (&cstream->retry_timer);
	cstream->state = NN_CSTREAM_STATE_CLOSING_TIMER;

	return;
	default:
	nn_assert (0);
	}
	}
	nn_assert (0);
	/******************************************************************************/
	/* FINISHING_WAITING state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_FINISHING_WAITING:
	nn_assert (0);
	/******************************************************************************/
	/* CONNECTING state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_CONNECTING:
	if (source == &cstream->usock) {
	switch (type) {
	case NN_USOCK_CONNECTED:
	nn_assert (0);
	case NN_USOCK_ERROR:

	/* Connecting failed. Wait a while before re-connecting. */
	nn_timer_start (&cstream->retry_timer,
	nn_cstream_compute_retry_ivl (cstream));
	cstream->state = NN_CSTREAM_STATE_WAITING;

	return;
	default:
	nn_assert (0);
	}
	}
	nn_assert (0);
	/******************************************************************************/
	/* CONNECTED state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_CONNECTED:
	nn_assert (0);
	/******************************************************************************/
	/* CLOSING_TIMER state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_CLOSING_TIMER:
	if (source == &cstream->retry_timer) {
	switch (type) {
	case NN_TIMER_CLOSED:
	nn_usock_close (&cstream->usock);
	cstream->state = NN_CSTREAM_STATE_CLOSING_USOCK;
	return;
	default:
	nn_assert (0);
	}
	}
	nn_assert (0);
	/******************************************************************************/
	/* CLOSING_USOCK state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_CLOSING_USOCK:
	if (source == &cstream->usock) {
	switch (type) {
	case NN_USOCK_CLOSED:
	cstream->state = NN_CSTREAM_STATE_CLOSED;

	nn_assert (0);
	return;
	default:
	nn_assert (0);
	}
	}
	nn_assert (0);
	/******************************************************************************/
	/* CLOSED state. */
	/******************************************************************************/
	case NN_CSTREAM_STATE_CLOSED:
	nn_assert (0);
	default:
	nn_assert (0);
	}
	}

	static int nn_cstream_close (struct nn_epbase *self)
	{
	struct nn_cstream *cstream;

	cstream = nn_cont (self, struct nn_cstream, epbase);

	/* Pass the event to the state machine. */
	nn_cstream_callback (&cstream->fsm, NULL, NN_CSTREAM_EVENT_CLOSE);
	}

	static int nn_cstream_compute_retry_ivl (struct nn_cstream *self)
	{
	int reconnect_ivl;
	int reconnect_ivl_max;
	size_t sz;
	int result;
	unsigned int random;

	/* Get relevant options' values. */
	sz = sizeof (reconnect_ivl);
	nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_RECONNECT_IVL,
	&reconnect_ivl, &sz);
	nn_assert (sz == sizeof (reconnect_ivl));
	sz = sizeof (reconnect_ivl_max);
	nn_epbase_getopt (&self->epbase, NN_SOL_SOCKET, NN_RECONNECT_IVL_MAX,
	&reconnect_ivl_max, &sz);
	nn_assert (sz == sizeof (reconnect_ivl_max));

	/* Negative number means that reconnect sequence is starting.
	The reconnect interval in this case is NN_RECONNECT_IVL. */
	if (self->retry_ivl < 0)
	self->retry_ivl = reconnect_ivl;

	/* Current retry_ivl will be returned to the caller. */
	result = self->retry_ivl;

	/* Re-compute new retry interval. */
	if (reconnect_ivl_max > 0 && reconnect_ivl_max > reconnect_ivl) {
	self->retry_ivl *= 2;
	if (self->retry_ivl > reconnect_ivl_max)
	self->retry_ivl = reconnect_ivl_max;
	}

	/* Randomise the result to prevent re-connection storms when network
	and/or server goes down and then up again. This may rise
	the reconnection interval at most twice and at most by one second. */
	nn_random_generate (&random, sizeof (random));
	result += (random % result % 1000);
	return result;
	}

	#if 0

	/* Private functions. */
	static int nn_cstream_compute_retry_ivl (struct nn_cstream *self);

	int nn_cstream_init (struct nn_cstream self, const char addr, void *hint,
	int (initsockfn) (struct nn_usock sock, int sndbuf, int rcvbuf),
	int (resolvefn) (const char addr,
	struct sockaddr_storage local, socklen_t locallen,
	struct sockaddr_storage remote, socklen_t remotelen))
	{
	nn_assert (0);
	}

	#if 0
	/******************************************************************************/
	/* State: WAITING */
	/******************************************************************************/

	static void nn_cstream_waiting_timeout (const struct nn_cp_sink **self,
	struct nn_aio_timer *timer);
	static const struct nn_cp_sink nn_cstream_state_waiting = {
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	nn_cstream_waiting_timeout,
	NULL
	};

	static void nn_cstream_waiting_timeout (const struct nn_cp_sink **self,
	struct nn_aio_timer *timer)
	{
	int rc;
	struct nn_cstream *cstream;
	struct sockaddr_storage local;
	socklen_t locallen;
	struct sockaddr_storage remote;
	socklen_t remotelen;

	cstream = nn_cont (self, struct nn_cstream, sink);

	/* Retry timer expired. Now we'll try to resolve the address. */
	rc = cstream->resolvefn (nn_epbase_getaddr (&cstream->epbase),
	&local, &locallen, &remote, &remotelen);

	/* If the address resolution have failed, wait and re-try. */
	if (rc < 0) {
	cstream->sink = &nn_cstream_state_waiting;
	nn_aio_timer_start (&cstream->retry_timer,
	nn_cstream_compute_retry_ivl (cstream));
	return;
	}

	/* Open the socket and start connecting. */
	cstream->sink = &nn_cstream_state_connecting;
	if (rc & NN_CSTREAM_DOBIND)
	nn_aio_usock_bind (&cstream->usock,
	(struct sockaddr*) &local, locallen);
	nn_aio_usock_connect (&cstream->usock,
	(struct sockaddr*) &remote, remotelen);
	}

	/******************************************************************************/
	/* State: CONNECTING */
	/******************************************************************************/

	static void nn_cstream_connecting_connected (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock);
	static void nn_cstream_connecting_err (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock, int errnum);
	static const struct nn_cp_sink nn_cstream_state_connecting = {
	NULL,
	NULL,
	nn_cstream_connecting_connected,
	NULL,
	nn_cstream_connecting_err,
	NULL,
	NULL,
	NULL
	};

	static void nn_cstream_connecting_connected (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock)
	{
	struct nn_cstream *cstream;

	cstream = nn_cont (self, struct nn_cstream, sink);

	/* TODO: Set current reconnect interval to the value of
	NN_RECONNECT_IVL. */

	/* Connect succeeded. Switch to the session state machine. */
	cstream->sink = &nn_cstream_state_connected;
	nn_stream_init (&cstream->stream, &cstream->epbase, &cstream->usock);
	}

	static void nn_cstream_connecting_err (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock, int errnum)
	{
	struct nn_cstream *cstream;

	cstream = nn_cont (self, struct nn_cstream, sink);

	/* Connect failed. Close the underlying socket. */
	cstream->sink = &nn_cstream_state_closing;
	nn_aio_usock_close (&cstream->usock);
	}

	/******************************************************************************/
	/* State: CONNECTED */
	/******************************************************************************/

	/* In this state control is yielded to the 'stream' state machine. */

	static void nn_cstream_connected_err (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock, int errnum);
	static const struct nn_cp_sink nn_cstream_state_connected = {
	NULL,
	NULL,
	NULL,
	NULL,
	nn_cstream_connected_err,
	NULL,
	NULL,
	NULL
	};

	static void nn_cstream_connected_err (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock, int errnum)
	{
	struct nn_cstream *cstream;

	cstream = nn_cont (self, struct nn_cstream, sink);

	/* The connection is broken. Reconnect. */
	cstream->sink = &nn_cstream_state_waiting;
	nn_cstream_waiting_timeout (&cstream->sink, &cstream->retry_timer);
	}

	/******************************************************************************/
	/* State: CLOSING */
	/******************************************************************************/

	static void nn_cstream_closing_closed (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock);
	static const struct nn_cp_sink nn_cstream_state_closing = {
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	nn_cstream_closing_closed,
	NULL,
	NULL
	};

	static void nn_cstream_closing_closed (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock)
	{
	int rc;
	struct nn_cstream *cstream;
	int sndbuf;
	int rcvbuf;
	size_t sz;

	cstream = nn_cont (self, struct nn_cstream, sink);

	/* Get the current values of NN_SNDBUF and NN_RCVBUF options. */
	sz = sizeof (sndbuf);
	nn_epbase_getopt (&cstream->epbase, NN_SOL_SOCKET, NN_SNDBUF, &sndbuf, &sz);
	nn_assert (sz == sizeof (sndbuf));
	sz = sizeof (rcvbuf);
	nn_epbase_getopt (&cstream->epbase, NN_SOL_SOCKET, NN_RCVBUF, &rcvbuf, &sz);
	nn_assert (sz == sizeof (rcvbuf));

	/* Create new socket. */
	rc = cstream->initsockfn (&cstream->usock, sndbuf, rcvbuf,
	nn_epbase_getcp (&cstream->epbase));
	errnum_assert (rc == 0, -rc);
	nn_aio_usock_setsink (&cstream->usock, &cstream->sink);

	/* Wait for the specified period. */
	cstream->sink = &nn_cstream_state_waiting;
	nn_aio_timer_start (&cstream->retry_timer,
	nn_cstream_compute_retry_ivl (cstream));
	}

	/******************************************************************************/
	/* State: TERMINATING */
	/******************************************************************************/

	static void nn_cstream_terminating_closed (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock);
	static const struct nn_cp_sink nn_cstream_state_terminating = {
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	nn_cstream_terminating_closed,
	NULL,
	NULL
	};

	static int nn_cstream_close (struct nn_epbase *self)
	{
	struct nn_cstream *cstream;

	cstream = nn_cont (self, struct nn_cstream, epbase);

	/* If termination is already underway, do nothing and let it continue. */
	if (cstream->sink == &nn_cstream_state_terminating)
	return -EINPROGRESS;

	/* If the connection exists, stop the session state machine. */
	if (cstream->sink == &nn_cstream_state_connected)
	nn_stream_term (&cstream->stream);

	/* Deallocate resources. */
	nn_aio_timer_term (&cstream->retry_timer);

	/* Close the socket, if needed. */
	cstream->sink = &nn_cstream_state_terminating;
	nn_aio_usock_close (&cstream->usock);

	return -EINPROGRESS;
	}

	static void nn_cstream_terminating_closed (const struct nn_cp_sink **self,
	struct nn_aio_usock *usock)
	{
	struct nn_cstream *cstream;

	cstream = nn_cont (self, struct nn_cstream, sink);

	nn_epbase_term (&cstream->epbase);
	nn_free (cstream);
	}

	#endif

	#endif