From b70b090a28ff4cbdce29a3ad030f7d51ce9079b2 Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@meshlink.io>
Date: Sun, 15 Mar 2020 16:24:34 +0100
Subject: [PATCH] Have try_bind() reuse the setup_*_listen_socket() functions.

This ensures try_bind() configures sockets exactly the same as the actual
listening sockets.
---
 src/meshlink.c  | 26 +++++++-------------------
 src/net.h       |  2 ++
 src/net_setup.c |  6 +++---
 3 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/src/meshlink.c b/src/meshlink.c
index ab3ab7ff..9f3b6ecd 100644
--- a/src/meshlink.c
+++ b/src/meshlink.c
@@ -577,7 +577,7 @@ static char *get_my_hostname(meshlink_handle_t *mesh, uint32_t flags) {
 	return hostport;
 }
 
-static bool try_bind(int port) {
+static bool try_bind(meshlink_handle_t *mesh, int port) {
 	struct addrinfo *ai = NULL;
 	struct addrinfo hint = {
 		.ai_flags = AI_PASSIVE,
@@ -598,16 +598,9 @@ static bool try_bind(int port) {
 	for(struct addrinfo *aip = ai; aip; aip = aip->ai_next) {
 		/* Try to bind to TCP. */
 
-		int tcp_fd = socket(aip->ai_family, SOCK_STREAM, IPPROTO_TCP);
+		int tcp_fd = setup_tcp_listen_socket(mesh, aip);
 
 		if(tcp_fd == -1) {
-			continue;
-		}
-
-		int result = bind(tcp_fd, aip->ai_addr, aip->ai_addrlen);
-		closesocket(tcp_fd);
-
-		if(result) {
 			if(errno == EADDRINUSE) {
 				/* If this port is in use for any address family, avoid it. */
 				success = false;
@@ -619,21 +612,16 @@ static bool try_bind(int port) {
 
 		/* If TCP worked, then we require that UDP works as well. */
 
-		int udp_fd = socket(aip->ai_family, SOCK_DGRAM, IPPROTO_UDP);
+		int udp_fd = setup_udp_listen_socket(mesh, aip);
 
 		if(udp_fd == -1) {
+			closesocket(tcp_fd);
 			success = false;
 			break;
 		}
 
-		result = bind(udp_fd, aip->ai_addr, aip->ai_addrlen);
+		closesocket(tcp_fd);
 		closesocket(udp_fd);
-
-		if(result) {
-			success = false;
-			break;
-		}
-
 		success = true;
 	}
 
@@ -645,7 +633,7 @@ int check_port(meshlink_handle_t *mesh) {
 	for(int i = 0; i < 1000; i++) {
 		int port = 0x1000 + prng(mesh, 0x8000);
 
-		if(try_bind(port)) {
+		if(try_bind(mesh, port)) {
 			free(mesh->myport);
 			xasprintf(&mesh->myport, "%d", port);
 			return port;
@@ -2554,7 +2542,7 @@ bool meshlink_set_port(meshlink_handle_t *mesh, int port) {
 		return true;
 	}
 
-	if(!try_bind(port)) {
+	if(!try_bind(mesh, port)) {
 		meshlink_errno = MESHLINK_ENETWORK;
 		return false;
 	}
diff --git a/src/net.h b/src/net.h
index cdb0cca5..cae63bf1 100644
--- a/src/net.h
+++ b/src/net.h
@@ -84,6 +84,8 @@ extern void handle_incoming_vpn_data(struct event_loop_t *loop, void *, int);
 extern void finish_connecting(struct meshlink_handle *mesh, struct connection_t *);
 extern void do_outgoing_connection(struct meshlink_handle *mesh, struct outgoing_t *);
 extern void handle_new_meta_connection(struct event_loop_t *loop, void *, int);
+extern int setup_tcp_listen_socket(struct meshlink_handle *mesh, const struct addrinfo *aip) __attribute__((__warn_unused_result__));
+extern int setup_udp_listen_socket(struct meshlink_handle *mesh, const struct addrinfo *aip) __attribute__((__warn_unused_result__));
 extern bool send_sptps_data(void *handle, uint8_t type, const void *data, size_t len);
 extern bool receive_sptps_record(void *handle, uint8_t type, const void *data, uint16_t len) __attribute__((__warn_unused_result__));
 extern void send_packet(struct meshlink_handle *mesh, struct node_t *, struct vpn_packet_t *);
diff --git a/src/net_setup.c b/src/net_setup.c
index d0e45003..238ae2d3 100644
--- a/src/net_setup.c
+++ b/src/net_setup.c
@@ -301,7 +301,7 @@ static bool load_node(meshlink_handle_t *mesh, const char *name, void *priv) {
 	return true;
 }
 
-static int setup_tcp_listen_socket(meshlink_handle_t *mesh, const struct addrinfo *aip) {
+int setup_tcp_listen_socket(meshlink_handle_t *mesh, const struct addrinfo *aip) {
 	int nfd = socket(aip->ai_family, SOCK_STREAM, IPPROTO_TCP);
 
 	if(nfd == -1) {
@@ -339,7 +339,7 @@ static int setup_tcp_listen_socket(meshlink_handle_t *mesh, const struct addrinf
 	return nfd;
 }
 
-static int setup_udp_socket(meshlink_handle_t *mesh, const struct addrinfo *aip) {
+int setup_udp_listen_socket(meshlink_handle_t *mesh, const struct addrinfo *aip) {
 	int nfd = socket(aip->ai_family, SOCK_DGRAM, IPPROTO_UDP);
 
 	if(nfd == -1) {
@@ -470,7 +470,7 @@ static bool add_listen_sockets(meshlink_handle_t *mesh) {
 
 		/* If TCP worked, then we require that UDP works as well. */
 
-		int udp_fd = setup_udp_socket(mesh, aip);
+		int udp_fd = setup_udp_listen_socket(mesh, aip);
 
 		if(udp_fd == -1) {
 			closesocket(tcp_fd);
-- 
2.39.5