Added comment for Win32 SO_RESUSEADDR

mongoose.c

@@ -548,6 +548,12 @@ static sock_t ns_open_listening_socket(union socket_address *sa) {
 
   if ((sock = socket(sa->sa.sa_family, SOCK_STREAM, 6)) != INVALID_SOCKET &&
 #ifndef _WIN32
+      // SO_RESUSEADDR is not enabled on Windows because the semantics of
+      // SO_REUSEADDR on UNIX and Windows is different. On Windows,
+      // SO_REUSEADDR allows to bind a socket to a port without error even if
+      // the port is already open by another program. This is not the behavior
+      // SO_REUSEADDR was designed for, and leads to hard-to-track failure
+      // scenarios. Therefore, SO_REUSEADDR was disabled on Windows.
       !setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *) &on, sizeof(on)) &&
 #endif
       !bind(sock, &sa->sa, sa->sa.sa_family == AF_INET ?