Use SO_REUSEPORT only on Linux, use SO_REUSEPORT_LB on FreeBSD

The SO_REUSEPORT socket option on Linux means something else on BSD
based systems.  On FreeBSD there's 1:1 option SO_REUSEPORT_LB, so we can
use that.

diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index 6f8c83a75f4fcf7b3be445faf72e00f58d593f08..8f6826ffa9b39de122d3dfcfb69a2b318a16bc28 100644 (file)
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -66,7 +66,7 @@ isc_nm_listenudp(isc_nm_t *mgr, isc_nmiface_t *iface, isc_nm_recv_cb_t cb,
 
        for (size_t i = 0; i < mgr->nworkers; i++) {
                uint16_t family = iface->addr.type.sa.sa_family;
-               int res;
+               int res = 0;
 
                isc__netievent_udplisten_t *ievent = NULL;
                isc_nmsocket_t *csock = &nsock->children[i];
@@ -84,22 +84,40 @@ isc_nm_listenudp(isc_nm_t *mgr, isc_nmiface_t *iface, isc_nm_recv_cb_t cb,
 
                /*
                 * This is SO_REUSE**** hell:
-                * On Linux SO_REUSEPORT allows multiple sockets to bind to
-                * the same host:port pair.
-                * On Windows the same thing is achieved with SO_REUSEADDR
+                *
+                * Generally, the SO_REUSEADDR socket option allows reuse of
+                * local addresses.  On Windows, it also allows a socket to
+                * forcibly bind to a port in use by another socket.
+                *
+                * On Linux, SO_REUSEPORT socket option allows sockets to be
+                * bound to an identical socket address. For UDP sockets, the
+                * use of this option can provide better distribution of
+                * incoming datagrams to multiple processes (or threads) as
+                * compared to the traditional technique of having multiple
+                * processes compete to receive datagrams on the same socket.
+                *
+                * On FreeBSD, the same thing is achieved with SO_REUSEPORT_LB.
+                *
                 */
-#ifdef WIN32
+#if defined(SO_REUSEADDR)
                res = setsockopt(csock->fd, SOL_SOCKET, SO_REUSEADDR,
                                 &(int){ 1 }, sizeof(int));
-#else  /* ifdef WIN32 */
+               RUNTIME_CHECK(res == 0);
+#endif
+#if defined(SO_REUSEPORT_LB)
+               res = setsockopt(csock->fd, SOL_SOCKET, SO_REUSEPORT_LB,
+                                &(int){ 1 }, sizeof(int));
+               RUNTIME_CHECK(res == 0);
+#elif defined(SO_REUSEPORT)
                res = setsockopt(csock->fd, SOL_SOCKET, SO_REUSEPORT,
                                 &(int){ 1 }, sizeof(int));
-#endif /* ifdef WIN32 */
                RUNTIME_CHECK(res == 0);
+#endif
 
 #ifdef SO_INCOMING_CPU
-               setsockopt(csock->fd, SOL_SOCKET, SO_INCOMING_CPU, &(int){ 1 },
-                          sizeof(int));
+               res = setsockopt(csock->fd, SOL_SOCKET, SO_INCOMING_CPU,
+                                &(int){ 1 }, sizeof(int));
+               RUNTIME_CHECK(res == 0);
 #endif
                ievent = isc__nm_get_ievent(mgr, netievent_udplisten);
                ievent->sock = csock;