hunt and peck for an open source port

diff --git a/src/lib/bio/fd_open.c b/src/lib/bio/fd_open.c
index 751a013cd4692048c5723669f397bc5a527ae423..1ddb5737d4202f964b177650d8916001ee894aa2 100644 (file)
--- a/src/lib/bio/fd_open.c
+++ b/src/lib/bio/fd_open.c
@@ -25,6 +25,7 @@
 #include <freeradius-devel/bio/fd_priv.h>
 #include <freeradius-devel/util/file.h>
 #include <freeradius-devel/util/cap.h>
+#include <freeradius-devel/util/rand.h>
 
 #include <sys/stat.h>
 #include <net/if.h>
@@ -723,14 +724,66 @@ static int fr_bio_fd_socket_bind(fr_bio_fd_t *my, fr_bio_fd_config_t const *cfg)
         */
        if (fr_ipaddr_to_sockaddr(&salocal, &salen, &my->info.socket.inet.src_ipaddr, my->info.socket.inet.src_port) < 0) return -1;
 
-       if (bind(my->info.socket.fd, (struct sockaddr *) &salocal, salen) < 0) {
-               fr_strerror_printf("Failed binding to socket: %s", fr_syserror(errno));
+       /*
+        *      If we have a fixed source port, just use that.
+        */
+       if (my->info.cfg->src_port || !my->info.cfg->src_port_start) {
+               if (bind(my->info.socket.fd, (struct sockaddr *) &salocal, salen) < 0) {
+                       fr_strerror_printf("Failed binding to socket: %s", fr_syserror(errno));
+                       return -1;
+               }
+       } else {
+               uint16_t src_port, current;
+               struct sockaddr_in *sin = (struct sockaddr_in *) &salocal;
+
+               fr_assert(my->info.cfg->src_port_start);
+               fr_assert(my->info.cfg->src_port_end);
+               fr_assert(my->info.cfg->src_port_end >= my->info.cfg->src_port_start);
+
+               src_port = fr_rand() % (my->info.cfg->src_port_end - my->info.cfg->src_port_start);
+
+               /*
+                *      We only care about sin_port, which is in the same location for sockaddr_in and sockaddr_in6.
+                */
+               fr_assert(sin->sin_port == 0);
+
+               sin->sin_port = htons(my->info.cfg->src_port_start + src_port);
+
+               /*
+                *      We've picked a random port in what is hopefully a large range.  If that works, we're
+                *      done.
+                */
+               if (bind(my->info.socket.fd, (struct sockaddr *) &salocal, salen) >= 0) goto done;
+
+               /*
+                *      Hunt & peck.  Which is horrible.
+                */
+               current = src_port;
+               while (true) {
+                       if (current == my->info.cfg->src_port_end) {
+                               current = my->info.cfg->src_port_start;
+                       } else {
+                               current++;
+                       }
+
+                       /*
+                        *      We've already checked this, so stop.
+                        */
+                       if (current == src_port) break;
+
+                       sin->sin_port = htons(current);
+
+                       if (bind(my->info.socket.fd, (struct sockaddr *) &salocal, salen) >= 0) goto done;
+               }
+
+               fr_strerror_const("There are no open ports between 'src_port_start' and 'src_port_end'");
                return -1;
        }
 
        /*
         *      The source IP may have changed, so get the new one.
         */
+done:
        return fr_bio_fd_socket_name(my);
 }