+ struct ifreq ifr;
+
+ memset(&ifr, 0, sizeof(ifr));
+ strncpy(ifr.ifr_ifrn.ifrn_name, iface, IFNAMSIZ);
+ ifr.ifr_ifrn.ifrn_name[IFNAMSIZ - 1] = 0;
+
+ if(setsockopt(nfd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr))) {
+ closesocket(nfd);
+ logger(DEBUG_ALWAYS, LOG_ERR, "Can't bind to interface %s: %s", iface,
+ sockstrerror(sockerrno));
+ return -1;
+ }
+
+#else
+ logger(DEBUG_ALWAYS, LOG_WARNING, "%s not supported on this platform", "BindToInterface");
+#endif
+ }
+
+ if(!try_bind(nfd, sa, "tcp")) {
+ return -1;
+ }
+
+ if(listen(nfd, 3)) {
+ closesocket(nfd);
+ logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "listen", sockstrerror(sockerrno));
+ return -1;
+ }
+
+ return nfd;
+}
+
+static void set_udp_buffer(int nfd, int type, const char *name, int size, bool warnings) {
+ if(!size) {
+ return;
+ }
+
+ if(setsockopt(nfd, SOL_SOCKET, type, (void *)&size, sizeof(size))) {
+ logger(DEBUG_ALWAYS, LOG_WARNING, "Can't set UDP %s to %i: %s", name, size, sockstrerror(sockerrno));
+ return;
+ }
+
+ if(!warnings) {
+ return;
+ }
+
+ // The system may cap the requested buffer size.
+ // Read back the value and check if it is now as requested.
+ int actual = -1;
+ socklen_t optlen = sizeof(actual);
+
+ if(getsockopt(nfd, SOL_SOCKET, type, (void *)&actual, &optlen)) {
+ logger(DEBUG_ALWAYS, LOG_WARNING, "Can't read back UDP %s: %s", name, sockstrerror(sockerrno));
+ } else if(optlen != sizeof(actual)) {
+ logger(DEBUG_ALWAYS, LOG_WARNING, "Can't read back UDP %s: unexpected returned optlen %d", name, (int)optlen);
+ } else if(actual < size) {
+ logger(DEBUG_ALWAYS, LOG_WARNING, "Can't set UDP %s to %i, the system set it to %i instead", name, size, actual);
+ }
+}
+
+int setup_vpn_in_socket(const sockaddr_t *sa) {
+ int nfd;
+ int option;
+
+ nfd = socket(sa->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
+
+ if(nfd < 0) {
+ logger(DEBUG_ALWAYS, LOG_ERR, "Creating UDP socket failed: %s", sockstrerror(sockerrno));
+ return -1;
+ }
+
+#ifdef FD_CLOEXEC
+ fcntl(nfd, F_SETFD, FD_CLOEXEC);
+#endif
+
+#ifdef O_NONBLOCK
+ {
+ int flags = fcntl(nfd, F_GETFL);
+
+ if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) {
+ closesocket(nfd);
+ logger(DEBUG_ALWAYS, LOG_ERR, "System call `%s' failed: %s", "fcntl",
+ strerror(errno));
+ return -1;
+ }
+ }
+#elif defined(WIN32)