socket-default: Use round-robin selection of sockets to read from

If multiple sockets are ready, we previously preferred the IPv4 non-NAT socket
over others. To handle all with equal priority, use a round-robin selection.

diff --git a/src/libcharon/plugins/socket_default/socket_default_socket.c b/src/libcharon/plugins/socket_default/socket_default_socket.c
index a0e4a54c5e5eae88cdc52e1b812dda35b0f3afaf..30e50d2d22957344f5a2b3dc5790c80ec136f2ee 100644 (file)
--- a/src/libcharon/plugins/socket_default/socket_default_socket.c
+++ b/src/libcharon/plugins/socket_default/socket_default_socket.c
@@ -141,6 +141,11 @@ struct private_socket_default_socket_t {
         * TRUE if the source address should be set on outbound packets
         */
        bool set_source;
+
+       /**
+        * A counter to implement round-robin selection of read sockets
+        */
+       u_int rr_counter;
 };
 
 METHOD(socket_t, receiver, status_t,
@@ -150,7 +155,7 @@ METHOD(socket_t, receiver, status_t,
        chunk_t data;
        packet_t *pkt;
        host_t *source = NULL, *dest = NULL;
-       int i, bytes_read = 0, selected = -1;
+       int i, rr, index, bytes_read = 0, selected = -1;
        bool oldstate;
        u_int16_t port = 0;
        struct pollfd pfd[] = {
@@ -164,7 +169,6 @@ METHOD(socket_t, receiver, status_t,
                this->port, this->natt, this->port, this->natt,
        };
 
-
        DBG2(DBG_NET, "waiting for data on sockets");
        oldstate = thread_cancelability(TRUE);
        if (poll(pfd, countof(pfd), -1) <= 0)
@@ -174,12 +178,16 @@ METHOD(socket_t, receiver, status_t,
        }
        thread_cancelability(oldstate);
 
+       rr = this->rr_counter++;
        for (i = 0; i < countof(pfd); i++)
        {
-               if (pfd[i].revents & POLLIN)
+               /* To serve all ports with equal priority, we use a round-robin
+                * scheme to choose the one to process in this invocation */
+               index = (rr + i) % countof(pfd);
+               if (pfd[index].revents & POLLIN)
                {
-                       selected = pfd[i].fd;
-                       port = ports[i];
+                       selected = pfd[index].fd;
+                       port = ports[index];
                        break;
                }
        }