More signal handling fixes

3 files changed, 45 insertions, 32 deletions

diff --git a/src/fastd.c b/src/fastd.c
index 378d641..c8f8e54 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -66,30 +66,30 @@
 fastd_context_t ctx = {};
 
 
-static volatile bool sighup = false;		/**< Is set to true when a SIGHUP is received */
-static volatile bool terminate = false;		/**< Is set to true when a SIGTERM, SIGQUIT or SIGINT is received */
-static volatile bool dump = false;		/**< Is set to true when a SIGUSR1 is received */
-static volatile bool sigchld = false;		/**< Is set to true when a SIGCHLD is received */
+volatile bool fastd_sig_hup = false;		/**< Is set to true when a SIGHUP is received */
+volatile bool fastd_sig_terminate = false;	/**< Is set to true when a SIGTERM, SIGQUIT or SIGINT is received */
+volatile bool fastd_sig_dump = false;		/**< Is set to true when a SIGUSR1 is received */
+volatile bool fastd_sig_chld = false;		/**< Is set to true when a SIGCHLD is received */
 
 
 /** SIGHUP handler */
 static void on_sighup(int signo UNUSED) {
-	sighup = true;
+	fastd_sig_hup = true;
 }
 
 /** SIGTERM, SIGQUIT and SIGINT handler */
 static void on_terminate(int signo UNUSED) {
-	terminate = true;
+	fastd_sig_terminate = true;
 }
 
 /** SIGUSR1 handler */
 static void on_sigusr1(int signo UNUSED) {
-	dump = true;
+	fastd_sig_dump = true;
 }
 
 /** SIGCHLD handler */
 static void on_sigchld(int signo UNUSED) {
-	sigchld = true;
+	fastd_sig_chld = true;
 }
 
 /** Installs signal handlers */
@@ -625,8 +625,8 @@ static inline void reap_zombies(void) {
 
 /** The \em real signal handlers */
 static inline void handle_signals(void) {
-	if (sighup) {
-		sighup = false;
+	if (fastd_sig_hup) {
+		fastd_sig_hup = false;
 
 		pr_info("reconfigure triggered");
 
@@ -634,13 +634,13 @@ static inline void handle_signals(void) {
 		init_peers();
 	}
 
-	if (dump) {
-		dump = false;
+	if (fastd_sig_dump) {
+		fastd_sig_dump = false;
 		dump_state();
 	}
 
-	if (sigchld) {
-		sigchld = false;
+	if (fastd_sig_chld) {
+		fastd_sig_chld = false;
 		reap_zombies();
 	}
 }
@@ -699,7 +699,7 @@ static inline void cleanup(void) {
 int main(int argc, char *argv[]) {
 	init(argc, argv);
 
-	while (!terminate)
+	while (!fastd_sig_terminate)
 		run();
 
 	cleanup();
diff --git a/src/fastd.h b/src/fastd.h
index f69f2f8..eeb2d3d 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -292,6 +292,11 @@ struct fastd_string_stack {
 extern fastd_context_t ctx;
 extern fastd_config_t conf;
 
+extern volatile bool fastd_sig_hup;
+extern volatile bool fastd_sig_terminate;
+extern volatile bool fastd_sig_dump;
+extern volatile bool fastd_sig_chld;
+
 
 void fastd_send(const fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, fastd_buffer_t buffer, size_t stat_size);
 void fastd_send_handshake(const fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, fastd_buffer_t buffer);
@@ -371,6 +376,11 @@ static inline size_t alignto(size_t l, size_t a) {
 	return block_count(l, a)*a;
 }
 
+/** Returns true if any unhandled signal in currently queued */
+static inline bool fastd_signalled(void) {
+	return (fastd_sig_hup || fastd_sig_terminate || fastd_sig_dump || fastd_sig_chld);
+}
+
 /** Returns the maximum payload size \em fastd is configured to transport */
 static inline size_t fastd_max_payload(void) {
 	switch (conf.mode) {
diff --git a/src/poll.c b/src/poll.c
index f05a345..a74d249 100644
--- a/src/poll.c
+++ b/src/poll.c
@@ -133,23 +133,19 @@ void fastd_poll_handle(void) {
 	if (timeout < 0 || timeout > maintenance_timeout)
 		timeout = maintenance_timeout;
 
-	sigset_t set, oldset;
+	sigset_t set;
 	sigemptyset(&set);
-	pthread_sigmask(SIG_SETMASK, &set, &oldset);
 
 	struct epoll_event events[16];
-	int ret = epoll_wait(ctx.epoll_fd, events, 16, timeout);
-	if (ret < 0) {
-		if (errno == EINTR)
-			return;
-
+	int ret = epoll_pwait(ctx.epoll_fd, events, 16, timeout, &set);
+	if (ret < 0 && errno != EINTR)
 		exit_errno("epoll_wait");
-	}
-
-	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 
 	fastd_update_time();
 
+	if (ret < 0)
+		return;
+
 	size_t i;
 	for (i = 0; i < (size_t)ret; i++) {
 		if (events[i].data.ptr == &ctx.tunfd) {
@@ -257,18 +253,25 @@ void fastd_poll_handle(void) {
 	sigemptyset(&set);
 	pthread_sigmask(SIG_SETMASK, &set, &oldset);
 
-	int ret = poll(VECTOR_DATA(ctx.pollfds), VECTOR_LEN(ctx.pollfds), timeout);
-	if (ret < 0) {
-		if (errno == EINTR)
-			return;
-
-		exit_errno("poll");
+	int ret = -1;
+
+	if (!fastd_signalled()) {
+		/*
+		  There is a race condition here: if a signal occurs after the fastd_signalled() check, but before the poll
+		  call, poll() will be called with its normal timeout, potentially delaying the actual signal handling. On
+		  OpenBSD we could use ppoll() to fix this, but on FreeBSD we're out of luck.
+		 */
+		ret = poll(VECTOR_DATA(ctx.pollfds), VECTOR_LEN(ctx.pollfds), timeout);
+		if (ret < 0 && errno != EINTR)
+			exit_errno("poll");
 	}
 
 	pthread_sigmask(SIG_SETMASK, &oldset, NULL);
-
 	fastd_update_time();
 
+	if (ret < 0)
+		return;
+
 	if (VECTOR_INDEX(ctx.pollfds, 0).revents & POLLIN)
 		fastd_tuntap_handle();
 	if (VECTOR_INDEX(ctx.pollfds, 1).revents & POLLIN)