Test for overflowing platform FD_SET size.

src/dbus.c

@@ -760,15 +760,13 @@ void set_dbus_listeners(int *maxfdp,
 	unsigned int flags = dbus_watch_get_flags(w->watch);
 	int fd = dbus_watch_get_unix_fd(w->watch);
 	
-	bump_maxfd(fd, maxfdp);
-	
 	if (flags & DBUS_WATCH_READABLE)
-	  FD_SET(fd, rset);
+	  bump_maxfd(rset, fd, maxfdp);
 	
 	if (flags & DBUS_WATCH_WRITABLE)
-	  FD_SET(fd, wset);
+	  bump_maxfd(wset, fd, maxfdp);
 	
-	FD_SET(fd, eset);
+	bump_maxfd(eset, fd, maxfdp);
       }
 }
 

src/dnsmasq.c

@@ -902,48 +902,32 @@ int main (int argc, char **argv)
 #ifdef HAVE_DHCP
       if (daemon->dhcp || daemon->relay4)
 	{
-	  FD_SET(daemon->dhcpfd, &rset);
+	  bump_maxfd(&rset, daemon->dhcpfd, &maxfd);
-	  bump_maxfd(daemon->dhcpfd, &maxfd);
 	  if (daemon->pxefd != -1)
-	    {
+	    bump_maxfd(&rset, daemon->pxefd, &maxfd);
-	      FD_SET(daemon->pxefd, &rset);
-	      bump_maxfd(daemon->pxefd, &maxfd);
-	    }
 	}
 #endif
 
 #ifdef HAVE_DHCP6
       if (daemon->doing_dhcp6 || daemon->relay6)
-	{
+	bump_maxfd(&rset, daemon->dhcp6fd, &maxfd);
-	  FD_SET(daemon->dhcp6fd, &rset);
-	  bump_maxfd(daemon->dhcp6fd, &maxfd);
-	}
 	
       if (daemon->doing_ra)
-	{
+	bump_maxfd(&rset, daemon->icmp6fd, &maxfd); 
-	  FD_SET(daemon->icmp6fd, &rset);
-	  bump_maxfd(daemon->icmp6fd, &maxfd); 
-	}
 #endif
     
 #ifdef HAVE_INOTIFY
       if (daemon->inotifyfd != -1)
-	{
+	bump_maxfd(&rset, daemon->inotifyfd, &maxfd);
-	  FD_SET(daemon->inotifyfd, &rset);
-	  bump_maxfd(daemon->inotifyfd, &maxfd);
-	}
 #endif
 
 #if defined(HAVE_LINUX_NETWORK)
-      FD_SET(daemon->netlinkfd, &rset);
+      bump_maxfd(&rset, daemon->netlinkfd, &maxfd);
-      bump_maxfd(daemon->netlinkfd, &maxfd);
 #elif defined(HAVE_BSD_NETWORK)
-      FD_SET(daemon->routefd, &rset);
+      bump_maxfd(&rset, daemon->routefd, &maxfd);
-      bump_maxfd(daemon->routefd, &maxfd);
 #endif
       
-      FD_SET(piperead, &rset);
+      bump_maxfd(&rset, piperead, &maxfd);
-      bump_maxfd(piperead, &maxfd);
 
 #ifdef HAVE_DHCP
 #  ifdef HAVE_SCRIPT
@@ -954,10 +938,7 @@ int main (int argc, char **argv)
 #    endif
 
       if (!helper_buf_empty())
-	{
+	bump_maxfd(&wset, daemon->helperfd, &maxfd);
-	  FD_SET(daemon->helperfd, &wset);
-	  bump_maxfd(daemon->helperfd, &maxfd);
-	}
 #  else
       /* need this for other side-effects */
       while (do_script_run(now));
@@ -1482,8 +1463,7 @@ static int set_dns_listeners(time_t now, fd_set *set, int *maxfdp)
   for (transfer = daemon->tftp_trans; transfer; transfer = transfer->next)
     {
       tftp++;
-      FD_SET(transfer->sockfd, set);
+      bump_maxfd(set, transfer->sockfd, maxfdp);
-      bump_maxfd(transfer->sockfd, maxfdp);
     }
 #endif
   
@@ -1492,27 +1472,18 @@ static int set_dns_listeners(time_t now, fd_set *set, int *maxfdp)
     get_new_frec(now, &wait, 0);
   
   for (serverfdp = daemon->sfds; serverfdp; serverfdp = serverfdp->next)
-    {
+    bump_maxfd(set, serverfdp->fd, maxfdp);
-      FD_SET(serverfdp->fd, set);
-      bump_maxfd(serverfdp->fd, maxfdp);
-    }
     
   if (daemon->port != 0 && !daemon->osport)
     for (i = 0; i < RANDOM_SOCKS; i++)
       if (daemon->randomsocks[i].refcount != 0)
-	{
+	bump_maxfd(set, daemon->randomsocks[i].fd, maxfdp);
-	  FD_SET(daemon->randomsocks[i].fd, set);
-	  bump_maxfd(daemon->randomsocks[i].fd, maxfdp);
-	}
 	  
   for (listener = daemon->listeners; listener; listener = listener->next)
     {
       /* only listen for queries if we have resources */
       if (listener->fd != -1 && wait == 0)
-	{
+	bump_maxfd(set, listener->fd, maxfdp);
-	  FD_SET(listener->fd, set);
-	  bump_maxfd(listener->fd, maxfdp);
-	}
 	
       /* death of a child goes through the select loop, so
 	 we don't need to explicitly arrange to wake up here */
@@ -1520,17 +1491,13 @@ static int set_dns_listeners(time_t now, fd_set *set, int *maxfdp)
 	for (i = 0; i < MAX_PROCS; i++)
 	  if (daemon->tcp_pids[i] == 0)
 	    {
-	      FD_SET(listener->tcpfd, set);
+	      bump_maxfd(set, listener->tcpfd, maxfdp);
-	      bump_maxfd(listener->tcpfd, maxfdp);
 	      break;
 	    }
 
 #ifdef HAVE_TFTP
       if (tftp <= daemon->tftp_max && listener->tftpfd != -1)
-	{
+	bump_maxfd(set, listener->tftpfd, maxfdp);
-	  FD_SET(listener->tftpfd, set);
-	  bump_maxfd(listener->tftpfd, maxfdp);
-	}
 #endif
 
     }
@@ -1822,10 +1789,7 @@ int icmp_ping(struct in_addr addr)
       
 #ifdef HAVE_DHCP6
       if (daemon->doing_ra)
-	{
+	bump_maxfd(&rset, daemon->icmp6fd, &maxfd); 
-	  FD_SET(daemon->icmp6fd, &rset);
-	  bump_maxfd(daemon->icmp6fd, &maxfd); 
-	}
 #endif
       
       rc = select(maxfd+1, &rset, &wset, NULL, &tv);

src/dnsmasq.h

@@ -1191,7 +1191,7 @@ int memcmp_masked(unsigned char *a, unsigned char *b, int len,
 		  unsigned int mask);
 int expand_buf(struct iovec *iov, size_t size);
 char *print_mac(char *buff, unsigned char *mac, int len);
-void bump_maxfd(int fd, int *max);
+void bump_maxfd(fd_set *set, int fd, int *max);
 int read_write(int fd, unsigned char *packet, int size, int rw);
 
 int wildcard_match(const char* wildcard, const char* match);

src/log.c

@@ -424,10 +424,7 @@ void my_syslog(int priority, const char *format, ...)
 void set_log_writer(fd_set *set, int *maxfdp)
 {
   if (entries && log_fd != -1 && connection_good)
-    {
+    bump_maxfd(set, log_fd, maxfdp);
-      FD_SET(log_fd, set);
-      bump_maxfd(log_fd, maxfdp);
-    }
 }
 
 void check_log_writer(fd_set *set)

src/util.c

@@ -570,10 +570,23 @@ char *print_mac(char *buff, unsigned char *mac, int len)
   return buff;
 }
 
-void bump_maxfd(int fd, int *max)
+void bump_maxfd(fd_set *set, int fd, int *max)
 {
-  if (fd > *max)
+#ifdef FD_SETSIZE
-    *max = fd;
+  if (fd >= FD_SETSIZE)
+    {
+      static int logged = 0;
+      if (!logged)
+	my_syslog(LOG_ERR, _("File descriptor overflows FS_SET"));
+      logged = 1;
+    }
+  else
+ #endif
+    {
+      FD_SET(fd, set);
+      if (fd > *max)
+	*max = fd;
+    }
 }
 
 /* rc is return from sendto and friends.