unix: explain SO_REUSEADDR and SO_REUSEPORT

joyent · Jan 31, 2012 · 45d7bd8 · 45d7bd8
1 parent cd16ba5
commit 45d7bd8
Showing 1 changed file with 9 additions and 1 deletion.
diff --git a/src/unix/udp.c b/src/unix/udp.c
@@ -340,7 +340,15 @@ static int uv__bind(uv_udp_t* handle,
     goto out;
   }
 
-#ifdef SO_REUSEPORT /* Apple's version of SO_REUSEADDR... */
+  /* On the BSDs, SO_REUSEADDR lets you reuse an address that's in the TIME_WAIT
+   * state (i.e. was until recently tied to a socket) while SO_REUSEPORT lets
+   * multiple processes bind to the same address. Yes, it's something of a
+   * misnomer but then again, SO_REUSEADDR was already taken.
+   *
+   * None of the above applies to Linux: SO_REUSEADDR implies SO_REUSEPORT on
+   * Linux and hence it does not have SO_REUSEPORT at all.
+   */
+#ifdef SO_REUSEPORT
   yes = 1;
   if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &yes, sizeof yes) == -1) {
     uv__set_sys_error(handle->loop, errno);