added signal handling without races

4 files changed, 142 insertions, 35 deletions

diff --git a/ChangeLog b/ChangeLog
index 2034049..97e74a6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2009.??.?? -- Version 0.?
+
+* added signal handling without races
+
 2009.05.01 -- Version 0.3
 
 * updated to new protocol specification (extended label and crypto role)
diff --git a/src/sig_handler.c b/src/sig_handler.c
index 6fd4b85..7a1ad74 100644
--- a/src/sig_handler.c
+++ b/src/sig_handler.c
@@ -36,29 +36,123 @@
 
 #include "log.h"
 #include <signal.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/select.h>
+#include <errno.h>
+
 #include "sig_handler.h"
 
-volatile sig_atomic_t signal_exit = 0;
+#include <stdio.h>
+
+
+static int sig_pipe_fds[2];
+
 
-void signal_init()
+static void sig_handler(int sig)
 {
-  signal(SIGINT, handle_signal);
-  signal(SIGQUIT, handle_signal);
-  signal(SIGTERM, handle_signal);
-  signal(SIGHUP, handle_signal);
-  signal(SIGUSR1, handle_signal);
-  signal(SIGUSR2, handle_signal);
+  sigset_t set;
+  int ret = read(sig_pipe_fds[0], &set, sizeof(sigset_t));
+  if(ret != sizeof(sigset_t))
+    sigemptyset(&set);
+
+  sigaddset(&set, sig);
+  ret = write(sig_pipe_fds[1], &set, sizeof(sigset_t));
+}
+
+
+int signal_init()
+{
+  if(pipe(sig_pipe_fds)) {
+    log_printf(ERROR, "signal handling init failed (pipe error: %s)", strerror(errno));
+    return -1;
+  }
+
+  int i;
+  for(i=0; i<2; ++i) {
+    int fd_flags = fcntl(sig_pipe_fds[i], F_GETFL);
+    if(fd_flags == -1) {
+      log_printf(ERROR, "signal handling init failed (pipe fd[%d] read flags error: %s)", i, strerror(errno));
+      return -1;
+    }
+    if(fcntl(sig_pipe_fds[i], F_SETFL, fd_flags | O_NONBLOCK) == -1){
+      log_printf(ERROR, "signal handling init failed (pipe fd[%d] write flags error: %s)", i, strerror(errno));
+      return -1;
+    }
+  }
+
+  struct sigaction act;
+  act.sa_handler = sig_handler;
+  sigfillset(&act.sa_mask);
+  act.sa_flags = 0;
+
+  if((sigaction(SIGINT, &act, NULL) < 0) ||
+     (sigaction(SIGQUIT, &act, NULL) < 0) ||
+     (sigaction(SIGTERM, &act, NULL) < 0) ||
+     (sigaction(SIGHUP, &act, NULL) < 0) ||
+     (sigaction(SIGUSR1, &act, NULL) < 0) ||
+     (sigaction(SIGUSR2, &act, NULL) < 0)) {
+
+    log_printf(ERROR, "signal handling init failed (sigaction error: %s)", strerror(errno));
+    close(sig_pipe_fds[0]);
+    close(sig_pipe_fds[1]);
+  }
+
+  return sig_pipe_fds[0];
 }
 
-void handle_signal(int sig)
+int signal_handle()
 {
-  switch(sig) {
-  case SIGINT: log_printf(NOTICE, "SIG-Int caught, exitting"); signal_exit = 1; break;
-  case SIGQUIT: log_printf(NOTICE, "SIG-Quit caught, exitting"); signal_exit = 1; break;
-  case SIGTERM: log_printf(NOTICE, "SIG-Term caught, exitting"); signal_exit = 1; break;
-  case SIGHUP: log_printf(NOTICE, "SIG-Hup caught"); break;
-  case SIGUSR1: log_printf(NOTICE, "SIG-Usr1 caught"); break;
-  case SIGUSR2: log_printf(NOTICE, "SIG-Usr2 caught"); break;
-  default: log_printf(NOTICE, "Signal %d caught, ignoring", sig); break;
+  sigset_t set, oldset, tmpset;
+
+  sigemptyset(&tmpset);
+  sigaddset(&tmpset, SIGINT);
+  sigaddset(&tmpset, SIGQUIT);
+  sigaddset(&tmpset, SIGTERM);
+  sigaddset(&tmpset, SIGHUP);
+  sigaddset(&tmpset, SIGUSR1);
+  sigaddset(&tmpset, SIGUSR2);
+  sigprocmask(SIG_BLOCK, &tmpset, &oldset);
+
+  int ret = read(sig_pipe_fds[0], &set, sizeof(sigset_t));
+  if(ret != sizeof(sigset_t))
+    sigemptyset(&set);
+
+  int return_value = 0;
+  int sig;
+  for(sig=1; sig < _NSIG; ++sig) {
+    if(sigismember(&set, sig)) {
+      switch(sig) {
+      case SIGINT: log_printf(NOTICE, "SIG-Int caught, exitting"); return_value = 1; break;
+      case SIGQUIT: log_printf(NOTICE, "SIG-Quit caught, exitting"); return_value = 1; break;
+      case SIGTERM: log_printf(NOTICE, "SIG-Term caught, exitting"); return_value = 1; break;
+      case SIGHUP: log_printf(NOTICE, "SIG-Hup caught"); break;
+      case SIGUSR1: log_printf(NOTICE, "SIG-Usr1 caught"); break;
+      case SIGUSR2: log_printf(NOTICE, "SIG-Usr2 caught"); break;
+      default: log_printf(WARNING, "unknown signal %d caught, ignoring", sig); break;
+      }
+      sigdelset(&set, sig);
+    }
   }
+
+  sigprocmask(SIG_SETMASK, &oldset, NULL);
+  return return_value;
+}
+
+void signal_stop()
+{
+  struct sigaction act;
+  act.sa_handler = SIG_DFL;
+  sigemptyset(&act.sa_mask);
+  act.sa_flags = 0;
+
+  sigaction(SIGINT, &act, NULL);
+  sigaction(SIGQUIT, &act, NULL);
+  sigaction(SIGTERM, &act, NULL);
+  sigaction(SIGHUP, &act, NULL);
+  sigaction(SIGUSR1, &act, NULL);
+  sigaction(SIGUSR2, &act, NULL);
+
+  close(sig_pipe_fds[0]);
+  close(sig_pipe_fds[1]);
 }
diff --git a/src/sig_handler.h b/src/sig_handler.h
index a7779be..9fd6386 100644
--- a/src/sig_handler.h
+++ b/src/sig_handler.h
@@ -37,9 +37,8 @@
 
 #include <signal.h>
 
-extern volatile sig_atomic_t signal_exit;
-
-void signal_init();
-void handle_signal(int sig);
+int signal_init();
+int signal_handle();
+void signal_stop();
 
 #endif
diff --git a/src/uanytun.c b/src/uanytun.c
index c9c6c44..c20cbeb 100644
--- a/src/uanytun.c
+++ b/src/uanytun.c
@@ -249,7 +249,7 @@ int main_loop(tun_device_t* dev, udp_socket_t* sock, options_t* opt)
   encrypted_packet_t encrypted_packet;
   encrypted_packet_init(&encrypted_packet, opt->auth_tag_length_);
   seq_nr_t seq_nr = 0;
-  fd_set readfds;
+  fd_set readfds, readyfds;
 
   cipher_t c;
   auth_algo_t aa;
@@ -260,36 +260,45 @@ int main_loop(tun_device_t* dev, udp_socket_t* sock, options_t* opt)
   if(ret)
     return ret;
 
-  signal_init();
+  FD_ZERO(&readfds);
+  FD_SET(dev->fd_, &readfds);
+  FD_SET(sock->fd_, &readfds);
+  int nfds = dev->fd_ > sock->fd_ ? dev->fd_ : sock->fd_;
+
   int return_value = 0;
-  while(!return_value) {
-    FD_ZERO(&readfds);
-    FD_SET(dev->fd_, &readfds);
-    FD_SET(sock->fd_, &readfds);
-    int nfds = dev->fd_ > sock->fd_ ? dev->fd_+1 : sock->fd_+1;
+  int sig_fd = signal_init();
+  if(sig_fd < 0)
+    return_value -1;
 
-    int ret = select(nfds, &readfds, NULL, NULL, NULL);
+  FD_SET(sig_fd, &readfds);
+  nfds = (nfds < sig_fd) ? sig_fd : nfds;
+
+  while(!return_value) {
+    memcpy(&readyfds, &readfds, sizeof(readyfds));
+    int ret = select(nfds + 1, &readyfds, NULL, NULL, NULL);
     if(ret == -1 && errno != EINTR) {
       log_printf(ERROR, "select returned with error: %s", strerror(errno));
       return_value = -1;
       break;
     }
-    if(!ret)
+    if(!ret || ret == -1)
       continue;
 
-    if(signal_exit) {
-      return_value = 1;
-      break;
+    if(FD_ISSET(sig_fd, &readyfds)) {
+      if(signal_handle()) {
+        return_value = 1;
+        break;
+      }
     }
 
-    if(FD_ISSET(dev->fd_, &readfds)) {
+    if(FD_ISSET(dev->fd_, &readyfds)) {
       return_value = process_tun_data(dev, sock, opt, &plain_packet, &encrypted_packet, &c, &aa, &kd, seq_nr);
       seq_nr++;
       if(return_value)
         break;
     }
 
-    if(FD_ISSET(sock->fd_, &readfds)) {
+    if(FD_ISSET(sock->fd_, &readyfds)) {
       return_value = process_sock_data(dev, sock, opt, &plain_packet, &encrypted_packet, &c, &aa, &kd, &seq_win); 
       if(return_value)
         break;
@@ -302,6 +311,7 @@ int main_loop(tun_device_t* dev, udp_socket_t* sock, options_t* opt)
   key_derivation_close(&kd);
 #endif
   seq_win_clear(&seq_win);
+  signal_stop();
 
   return return_value;
 }