The Tor Browser: netwerk/sctp/src/netinet/sctp_callout.c@ac0c01689b40 (annotated)

netwerk/sctp/src/netinet/sctp_callout.c@ac0c01689b40 (annotated)

netwerk/sctp/src/netinet/sctp_callout.c

Thu, 15 Jan 2015 15:59:08 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:59:08 +0100
branch: TOR_BUG_9701
changeset 10: ac0c01689b40
permissions: -rwxr-xr-x

Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /*-
  * Copyright (c) 2001-2007, by Cisco Systems, Inc. All rights reserved.
  * Copyright (c) 2008-2012, by Randall Stewart. All rights reserved.
  * Copyright (c) 2008-2012, by Michael Tuexen. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *
  * a) Redistributions of source code must retain the above copyright notice,
  *    this list of conditions and the following disclaimer.
  *
  * b) Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the distribution.
  *
  * c) Neither the name of Cisco Systems, Inc. nor the names of its
  *    contributors may be used to endorse or promote products derived
  *    from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 #if defined(__Userspace__)
 #include <sys/types.h>
 #if !defined (__Userspace_os_Windows)
 #include <sys/wait.h>
 #include <unistd.h>
 #include <pthread.h>
 #endif
 #if defined(__Userspace_os_NaCl)
 #include <sys/select.h>
 #endif
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include <errno.h>
 #include <netinet/sctp_sysctl.h>
 #include <netinet/sctp_pcb.h>
 #else
 #include <netinet/sctp_os.h>
 #include <netinet/sctp_callout.h>
 #include <netinet/sctp_pcb.h>
 #endif
 /*
  * Callout/Timer routines for OS that doesn't have them
  */
 #if defined(__APPLE__) || defined(__Userspace__)
 int ticks = 0;
 #else
 extern int ticks;
 #endif
 /*
  * SCTP_TIMERQ_LOCK protects:
  * - SCTP_BASE_INFO(callqueue)
  * - sctp_os_timer_current: current timer in process
  * - sctp_os_timer_next: next timer to check
  */
 static sctp_os_timer_t *sctp_os_timer_current = NULL;
 static sctp_os_timer_t *sctp_os_timer_next = NULL;
 void
 sctp_os_timer_init(sctp_os_timer_t *c)
 {
 	bzero(c, sizeof(*c));
 }
 void
 sctp_os_timer_start(sctp_os_timer_t *c, int to_ticks, void (*ftn) (void *),
                     void *arg)
 {
 	/* paranoia */
 	if ((c == NULL) || (ftn == NULL))
 	    return;
 	SCTP_TIMERQ_LOCK();
 	/* check to see if we're rescheduling a timer */
 	if (c->c_flags & SCTP_CALLOUT_PENDING) {
 		if (c == sctp_os_timer_next) {
 			sctp_os_timer_next = TAILQ_NEXT(c, tqe);
 		}
 		TAILQ_REMOVE(&SCTP_BASE_INFO(callqueue), c, tqe);
 		/*
 		 * part of the normal "stop a pending callout" process
 		 * is to clear the CALLOUT_ACTIVE and CALLOUT_PENDING
 		 * flags.  We don't bother since we are setting these
 		 * below and we still hold the lock.
 		 */
 	}
 	/*
 	 * We could unlock/splx here and lock/spl at the TAILQ_INSERT_TAIL,
 	 * but there's no point since doing this setup doesn't take much time.
 	 */
 	if (to_ticks <= 0)
 		to_ticks = 1;
 	c->c_arg = arg;
 	c->c_flags = (SCTP_CALLOUT_ACTIVE | SCTP_CALLOUT_PENDING);
 	c->c_func = ftn;
 	c->c_time = ticks + to_ticks;
 	TAILQ_INSERT_TAIL(&SCTP_BASE_INFO(callqueue), c, tqe);
 	SCTP_TIMERQ_UNLOCK();
 }
 int
 sctp_os_timer_stop(sctp_os_timer_t *c)
 {
 	SCTP_TIMERQ_LOCK();
 	/*
 	 * Don't attempt to delete a callout that's not on the queue.
 	 */
 	if (!(c->c_flags & SCTP_CALLOUT_PENDING)) {
 		c->c_flags &= ~SCTP_CALLOUT_ACTIVE;
 		SCTP_TIMERQ_UNLOCK();
 		return (0);
 	}
 	c->c_flags &= ~(SCTP_CALLOUT_ACTIVE | SCTP_CALLOUT_PENDING);
 	if (c == sctp_os_timer_next) {
 		sctp_os_timer_next = TAILQ_NEXT(c, tqe);
 	}
 	TAILQ_REMOVE(&SCTP_BASE_INFO(callqueue), c, tqe);
 	SCTP_TIMERQ_UNLOCK();
 	return (1);
 }
 static void
 sctp_handle_tick(int delta)
 {
 	sctp_os_timer_t *c;
 	void (*c_func)(void *);
 	void *c_arg;
 	SCTP_TIMERQ_LOCK();
 	/* update our tick count */
 	ticks += delta;
 	c = TAILQ_FIRST(&SCTP_BASE_INFO(callqueue));
 	while (c) {
 		if (c->c_time <= ticks) {
 			sctp_os_timer_next = TAILQ_NEXT(c, tqe);
 			TAILQ_REMOVE(&SCTP_BASE_INFO(callqueue), c, tqe);
 			c_func = c->c_func;
 			c_arg = c->c_arg;
 			c->c_flags &= ~SCTP_CALLOUT_PENDING;
 			sctp_os_timer_current = c;
 			SCTP_TIMERQ_UNLOCK();
 			c_func(c_arg);
 			SCTP_TIMERQ_LOCK();
 			sctp_os_timer_current = NULL;
 			c = sctp_os_timer_next;
 		} else {
 			c = TAILQ_NEXT(c, tqe);
 		}
 	}
 	sctp_os_timer_next = NULL;
 	SCTP_TIMERQ_UNLOCK();
 }
 #if defined(__APPLE__)
 void
 sctp_timeout(void *arg SCTP_UNUSED)
 {
 	sctp_handle_tick(SCTP_BASE_VAR(sctp_main_timer_ticks));
 	sctp_start_main_timer();
 }
 #endif
 #if defined(__Userspace__)
 #define TIMEOUT_INTERVAL 10
 void *
 user_sctp_timer_iterate(void *arg)
 {
 	for (;;) {
 #if defined (__Userspace_os_Windows)
 		Sleep(TIMEOUT_INTERVAL);
 #else
 		struct timeval timeout;
 		timeout.tv_sec  = 0;
 		timeout.tv_usec = 1000 * TIMEOUT_INTERVAL;
 		select(0, NULL, NULL, NULL, &timeout);
 #endif
 		if (SCTP_BASE_VAR(timer_thread_should_exit)) {
 			break;
 		}
 		sctp_handle_tick(MSEC_TO_TICKS(TIMEOUT_INTERVAL));
 	}
 	return (NULL);
 }
 void
 sctp_start_timer(void)
 {
 	/*
 	 * No need to do SCTP_TIMERQ_LOCK_INIT();
 	 * here, it is being done in sctp_pcb_init()
 	 */
 #if defined (__Userspace_os_Windows)
 	if ((SCTP_BASE_VAR(timer_thread) = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)user_sctp_timer_iterate, NULL, 0, NULL)) == NULL) {
 		SCTP_PRINTF("ERROR; Creating ithread failed\n");
 	}
 #else
 	int rc;
 	rc = pthread_create(&SCTP_BASE_VAR(timer_thread), NULL, user_sctp_timer_iterate, NULL);
 	if (rc) {
 		SCTP_PRINTF("ERROR; return code from pthread_create() is %d\n", rc);
 	}
 #endif
 }
 #endif

The Tor Browser / annotate

netwerk/sctp/src/netinet/sctp_callout.c@ac0c01689b40 (annotated)

netwerk/sctp/src/netinet/sctp_callout.c