Start of fastopen support.

adsbus/incoming.c

@@ -65,7 +65,7 @@ static void incoming_handler(struct peer *peer) {
 			local_hbuf, local_sbuf,
 			peer_hbuf, peer_sbuf);
 
-	socket_init(fd);
+	socket_connected_init(fd);
 
 	incoming->handler(fd, incoming->passthrough, NULL);
 }
@@ -99,6 +99,8 @@ static void incoming_listen(struct incoming *incoming) {
 			continue;
 		}
 
+		socket_bound_init(incoming->peer.fd);
+
 		assert(listen(incoming->peer.fd, 255) == 0);
 		break;
 	}

adsbus/outgoing.c

@@ -60,7 +60,8 @@ static void outgoing_connect_next(struct outgoing *outgoing) {
 	outgoing->peer.fd = socket(outgoing->addr->ai_family, outgoing->addr->ai_socktype | SOCK_NONBLOCK | SOCK_CLOEXEC, outgoing->addr->ai_protocol);
 	assert(outgoing->peer.fd >= 0);
 
-	int result = connect(outgoing->peer.fd, outgoing->addr->ai_addr, outgoing->addr->ai_addrlen);
+	char buf[1];
+	int result = (int) sendto(outgoing->peer.fd, buf, 0, MSG_FASTOPEN, outgoing->addr->ai_addr, outgoing->addr->ai_addrlen);
 	outgoing_connect_result(outgoing, result == 0 ? result : errno);
 }
 
@@ -91,7 +92,7 @@ static void outgoing_connect_result(struct outgoing *outgoing, int result) {
 		case 0:
 			fprintf(stderr, "O %s: Connected to %s/%s\n", outgoing->id, hbuf, sbuf);
 			freeaddrinfo(outgoing->addrs);
-			socket_init(outgoing->peer.fd);
+			socket_connected_init(outgoing->peer.fd);
 			outgoing->attempt = 0;
 			int fd = outgoing->peer.fd;
 			outgoing->peer.fd = -1;

adsbus/socket.c

@@ -7,7 +7,12 @@
 
 #include "socket.h"
 
-void socket_init(int fd) {
+void socket_bound_init(int fd) {
+	int qlen = 5;
+	assert(!setsockopt(fd, SOL_TCP, TCP_FASTOPEN, &qlen, sizeof(qlen)));
+}
+
+void socket_connected_init(int fd) {
 	int optval = 1;
 	assert(!setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &optval, sizeof(optval)));
 	optval = 30;

adsbus/socket.h

@@ -1,3 +1,4 @@
 #pragma once
 
-void socket_init(int);
+void socket_bound_init(int);
+void socket_connected_init(int);