Scale the DNS random scket pool on the value of dns-forward-max.

CHANGELOG

@@ -62,6 +62,9 @@ version 2.85
 	behaviour can be restored using the min-port and max-port config
 	switches should that be a concern.
 
+	Scale the size of the DNS random-port pool based on the
+	value of the --dns-forward-max configuration.
+
 	
 version 2.84
 	Fix a problem, introduced in 2.83, which could see DNS replies

src/config.h

@@ -29,7 +29,6 @@
 #define UDP_TEST_TIME 60 /* How often to reset our idea of max packet size. */
 #define SERVERS_LOGGED 30 /* Only log this many servers when logging state */
 #define LOCALS_LOGGED 8 /* Only log this many local addresses when logging state */
-#define RANDOM_SOCKS 64 /* max simultaneous random ports */
 #define LEASE_RETRY 60 /* on error, retry writing leasefile after LEASE_RETRY seconds */
 #define CACHESIZ 150 /* default cache size */
 #define TTL_FLOOR_LIMIT 3600 /* don't allow --min-cache-ttl to raise TTL above this under any circumstances */

src/dnsmasq.c

@@ -399,6 +399,14 @@ int main (int argc, char **argv)
       cache_init();
       blockdata_init();
       hash_questions_init();
+
+      /* Scale random socket pool by ftabsize, but
+	 limit it based on available fds. */
+      daemon->numrrand = daemon->ftabsize/2;
+      if (daemon->numrrand > max_fd/3)
+	daemon->numrrand = max_fd/3;
+      /* safe_malloc returns zero'd memory */
+      daemon->randomsocks = safe_malloc(daemon->numrrand * sizeof(struct randfd));
     }
 
 #ifdef HAVE_INOTIFY
@@ -987,7 +995,7 @@ int main (int argc, char **argv)
 	 a single file will be sent to may clients (the file only needs
 	 one fd). */
 
-      max_fd -= 30; /* use other than TFTP */
+      max_fd -= 30 + daemon->numrrand; /* use other than TFTP */
       
       if (max_fd < 0)
 	max_fd = 5;
@@ -1700,7 +1708,7 @@ static int set_dns_listeners(time_t now)
   for (serverfdp = daemon->sfds; serverfdp; serverfdp = serverfdp->next)
     poll_listen(serverfdp->fd, POLLIN);
     
-  for (i = 0; i < RANDOM_SOCKS; i++)
+  for (i = 0; i < daemon->numrrand; i++)
     if (daemon->randomsocks[i].refcount != 0)
       poll_listen(daemon->randomsocks[i].fd, POLLIN);
 
@@ -1752,7 +1760,7 @@ static void check_dns_listeners(time_t now)
     if (poll_check(serverfdp->fd, POLLIN))
       reply_query(serverfdp->fd, now);
   
-  for (i = 0; i < RANDOM_SOCKS; i++)
+  for (i = 0; i < daemon->numrrand; i++)
     if (daemon->randomsocks[i].refcount != 0 && 
 	poll_check(daemon->randomsocks[i].fd, POLLIN))
       reply_query(daemon->randomsocks[i].fd, now);

src/dnsmasq.h

@@ -1130,7 +1130,8 @@ extern struct daemon {
   pid_t tcp_pids[MAX_PROCS];
   int tcp_pipes[MAX_PROCS];
   int pipe_to_parent;
-  struct randfd randomsocks[RANDOM_SOCKS];
+  int numrrand;
+  struct randfd *randomsocks;
   struct randfd_list *rfl_spare, *rfl_poll;
   int v6pktinfo; 
   struct addrlist *interface_addrs; /* list of all addresses/prefix lengths associated with all local interfaces */

src/forward.c

@@ -2218,7 +2218,7 @@ int allocate_rfd(struct randfd_list **fdlp, struct server *serv)
    
   /* limit the number of sockets we have open to avoid starvation of 
      (eg) TFTP. Once we have a reasonable number, randomness should be OK */
-  for (i = 0; i < RANDOM_SOCKS; i++)
+  for (i = 0; i < daemon->numrrand; i++)
     if (daemon->randomsocks[i].refcount == 0)
       {
 	if ((fd = random_sock(serv)) != -1)
@@ -2233,9 +2233,9 @@ int allocate_rfd(struct randfd_list **fdlp, struct server *serv)
   
   /* No free ones or cannot get new socket, grab an existing one */
   if (!rfd)
-    for (j = 0; j < RANDOM_SOCKS; j++)
+    for (j = 0; j < daemon->numrrand; j++)
       {
-	i = (j + finger) % RANDOM_SOCKS;
+	i = (j + finger) % daemon->numrrand;
 	if (daemon->randomsocks[i].refcount != 0 &&
 	    server_isequal(serv, daemon->randomsocks[i].serv) &&
 	    daemon->randomsocks[i].refcount != 0xfffe)
@@ -2247,7 +2247,7 @@ int allocate_rfd(struct randfd_list **fdlp, struct server *serv)
 	  }
       }
 
-  if (j == RANDOM_SOCKS)
+  if (j == daemon->numrrand)
     {
       struct randfd_list *rfl_poll;
 
@@ -2538,7 +2538,7 @@ void server_gone(struct server *server)
 
   /* If any random socket refers to this server, NULL the reference.
      No more references to the socket will be created in the future. */
-  for (i = 0; i < RANDOM_SOCKS; i++)
+  for (i = 0; i < daemon->numrrand; i++)
     if (daemon->randomsocks[i].refcount != 0 && daemon->randomsocks[i].serv == server)
       daemon->randomsocks[i].serv = NULL;