Don't use SOL_IP and SOL_IPV6.

These macros do not exist on all platforms, instead one should use
IPPROTO_IP and IPPROTO_IPV6. This fixes a bug on macOS where the
IPV6_V6ONLY flag would not be applied and could result in IPv4 sockets
not working.

src/net_packet.c

@@ -580,18 +580,18 @@ static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 		listen_socket[n->sock].priority = origpriority;
 
 		switch(listen_socket[n->sock].sa.sa.sa_family) {
-#if defined(SOL_IP) && defined(IP_TOS)
+#if defined(IP_TOS)
 
 		case AF_INET:
 			ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting IPv4 outgoing packet priority to %d", origpriority);
 
-			if(setsockopt(listen_socket[n->sock].udp, SOL_IP, IP_TOS, (void *)&origpriority, sizeof(origpriority))) { /* SO_PRIORITY doesn't seem to work */
+			if(setsockopt(listen_socket[n->sock].udp, IPPROTO_IP, IP_TOS, (void *)&origpriority, sizeof(origpriority))) { /* SO_PRIORITY doesn't seem to work */
 				logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
 			}
 
 			break;
 #endif
-#if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS)
+#if defined(IPV6_TCLASS)
 
 		case AF_INET6:
 			ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting IPv6 outgoing packet priority to %d", origpriority);

src/net_socket.c

@@ -77,12 +77,12 @@ static void configure_tcp(connection_t *c) {
 	setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&option, sizeof(option));
 #endif
 
-#if defined(SOL_IP) && defined(IP_TOS) && defined(IPTOS_LOWDELAY)
+#if defined(IP_TOS) && defined(IPTOS_LOWDELAY)
 	option = IPTOS_LOWDELAY;
-	setsockopt(c->socket, SOL_IP, IP_TOS, (void *)&option, sizeof(option));
+	setsockopt(c->socket, IPPROTO_IP, IP_TOS, (void *)&option, sizeof(option));
 #endif
 
-#if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS) && defined(IPTOS_LOWDELAY)
+#if defined(IPV6_TCLASS) && defined(IPTOS_LOWDELAY)
 	option = IPTOS_LOWDELAY;
 	setsockopt(c->socket, IPPROTO_IPV6, IPV6_TCLASS, (void *)&option, sizeof(option));
 #endif
@@ -142,12 +142,14 @@ int setup_listen_socket(const sockaddr_t *sa) {
 	option = 1;
 	setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
 
-#if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
+#if defined(IPV6_V6ONLY)
 
 	if(sa->sa.sa_family == AF_INET6) {
-		setsockopt(nfd, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
+		setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 	}
 
+#else
+#warning IPV6_V6ONLY not defined
 #endif
 
 	if(get_config_string(lookup_config(config_tree, "BindToInterface"), &iface)) {
@@ -238,7 +240,7 @@ int setup_vpn_in_socket(const sockaddr_t *sa) {
 		logger(LOG_WARNING, "Can't set UDP SO_SNDBUF to %i: %s", udp_sndbuf, strerror(errno));
 	}
 
-#if defined(IPPROTO_IPV6) && defined(IPV6_V6ONLY)
+#if defined(IPV6_V6ONLY)
 
 	if(sa->sa.sa_family == AF_INET6) {
 		setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
@@ -250,14 +252,14 @@ int setup_vpn_in_socket(const sockaddr_t *sa) {
 #define IP_DONTFRAGMENT IP_DONTFRAG
 #endif
 
-#if defined(SOL_IP) && defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
+#if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
 
 	if(myself->options & OPTION_PMTU_DISCOVERY) {
 		option = IP_PMTUDISC_DO;
-		setsockopt(nfd, SOL_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
+		setsockopt(nfd, IPPROTO_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
 	}
 
-#elif defined(IPPROTO_IP) && defined(IP_DONTFRAGMENT)
+#elif defined(IP_DONTFRAGMENT)
 
 	if(myself->options & OPTION_PMTU_DISCOVERY) {
 		option = 1;
@@ -266,14 +268,14 @@ int setup_vpn_in_socket(const sockaddr_t *sa) {
 
 #endif
 
-#if defined(SOL_IPV6) && defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
+#if defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
 
 	if(myself->options & OPTION_PMTU_DISCOVERY) {
 		option = IPV6_PMTUDISC_DO;
-		setsockopt(nfd, SOL_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
+		setsockopt(nfd, IPPROTO_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
 	}
 
-#elif defined(IPPROTO_IPV6) && defined(IPV6_DONTFRAG)
+#elif defined(IPV6_DONTFRAG)
 
 	if(myself->options & OPTION_PMTU_DISCOVERY) {
 		option = 1;
@@ -509,11 +511,11 @@ connect:
 #endif
 
 	if(proxytype != PROXY_EXEC) {
-#if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
+#if defined(IPV6_V6ONLY)
 		int option = 1;
 
 		if(c->address.sa.sa_family == AF_INET6) {
-			setsockopt(c->socket, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
+			setsockopt(c->socket, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof(option));
 		}
 
 #endif