Initial pass at async resolving. This is ugly and leaks memory and I hate it, so dedicated thread incoming.

adsbus/Makefile

@@ -1,11 +1,11 @@
 CC ?= clang
 CFLAGS ?= -Wall -Werror -O4 -g --std=gnu11 --pedantic-errors -fPIE -pie -fstack-protector-strong
 LDFLAGS ?= $(CFLAGS) -Wl,-z,relro -Wl,-z,now
-LIBS ?= -ljansson
+LIBS ?= -ljansson -lanl
 
 OBJ_NETWORK = incoming.o outgoing.o receive.o send.o
 OBJ_PROTOCOL = airspy_adsb.o beast.o json.o raw.o stats.o
-OBJ_UTIL = buf.o hex.o opts.o packet.o peer.o rand.o server.o uuid.o wakeup.o
+OBJ_UTIL = buf.o hex.o opts.o packet.o peer.o rand.o resolve.o server.o uuid.o wakeup.o
 
 all: adsbus
 

adsbus/incoming.c

@@ -11,6 +11,7 @@
 #include <unistd.h>
 
 #include "peer.h"
+#include "resolve.h"
 #include "wakeup.h"
 #include "uuid.h"
 
@@ -21,6 +22,8 @@ struct incoming {
 	char id[UUID_LEN];
 	char *node;
 	char *service;
+	struct addrinfo *addrs;
+	const char *error;
 	uint32_t attempt;
 	incoming_connection_handler handler;
 	void *passthrough;
@@ -71,25 +74,9 @@ static void incoming_del(struct incoming *incoming) {
 	free(incoming);
 }
 
-static void incoming_resolve(struct incoming *incoming) {
-	fprintf(stderr, "I %s: Resolving %s/%s...\n", incoming->id, incoming->node, incoming->service);
-
-	struct addrinfo hints = {
-		.ai_family = AF_UNSPEC,
-		.ai_socktype = SOCK_STREAM,
-		.ai_flags = AI_PASSIVE | AI_V4MAPPED | AI_ADDRCONFIG,
-	};
-
-	struct addrinfo *addrs;
-	int gai_err = getaddrinfo(incoming->node, incoming->service, &hints, &addrs);
-	if (gai_err) {
-		fprintf(stderr, "I %s: Failed to resolve %s/%s: %s\n", incoming->id, incoming->node, incoming->service, gai_strerror(gai_err));
-		incoming_retry(incoming);
-		return;
-	}
-
+static void incoming_listen(struct incoming *incoming) {
 	struct addrinfo *addr;
-	for (addr = addrs; addr; addr = addr->ai_next) {
+	for (addr = incoming->addrs; addr; addr = addr->ai_next) {
 		char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
 		assert(getnameinfo(addr->ai_addr, addr->ai_addrlen, hbuf, sizeof(hbuf), sbuf, sizeof(sbuf), NI_NUMERICHOST | NI_NUMERICSERV) == 0);
 		fprintf(stderr, "I %s: Listening on %s/%s...\n", incoming->id, hbuf, sbuf);
@@ -110,7 +97,7 @@ static void incoming_resolve(struct incoming *incoming) {
 		break;
 	}
 
-	freeaddrinfo(addrs);
+	freeaddrinfo(incoming->addrs);
 
 	if (addr == NULL) {
 		fprintf(stderr, "I %s: Failed to bind any addresses for %s/%s...\n", incoming->id, incoming->node, incoming->service);
@@ -122,6 +109,23 @@ static void incoming_resolve(struct incoming *incoming) {
 	peer_epoll_add((struct peer *) incoming, EPOLLIN);
 }
 
+static void incoming_resolve_handler(struct peer *peer) {
+	struct incoming *incoming = (struct incoming *) peer;
+	if (incoming->addrs) {
+		incoming_listen(incoming);
+	} else {
+		fprintf(stderr, "I %s: Failed to resolve %s/%s: %s\n", incoming->id, incoming->node, incoming->service, incoming->error);
+		incoming_retry(incoming);
+	}
+}
+
+static void incoming_resolve(struct incoming *incoming) {
+	fprintf(stderr, "I %s: Resolving %s/%s...\n", incoming->id, incoming->node, incoming->service);
+	incoming->peer.fd = -1;
+	incoming->peer.event_handler = incoming_resolve_handler;
+	resolve((struct peer *) incoming, incoming->node, incoming->service, AI_PASSIVE, &incoming->addrs, &incoming->error);
+}
+
 static void incoming_resolve_wrapper(struct peer *peer) {
 	incoming_resolve((struct incoming *) peer);
 }

adsbus/outgoing.c

@@ -9,6 +9,7 @@
 #include <unistd.h>
 
 #include "peer.h"
+#include "resolve.h"
 #include "wakeup.h"
 #include "uuid.h"
 
@@ -21,6 +22,7 @@ struct outgoing {
 	char *service;
 	struct addrinfo *addrs;
 	struct addrinfo *addr;
+	const char *error;
 	uint32_t attempt;
 	outgoing_connection_handler handler;
 	void *passthrough;
@@ -110,22 +112,22 @@ static void outgoing_connect_result(struct outgoing *outgoing, int result) {
 	}
 }
 
+static void outgoing_resolve_handler(struct peer *peer) {
+	struct outgoing *outgoing = (struct outgoing *) peer;
+	if (outgoing->addrs) {
+		outgoing->addr = outgoing->addrs;
+		outgoing_connect_next(outgoing);
+	} else {
+		fprintf(stderr, "O %s: Failed to resolve %s/%s: %s\n", outgoing->id, outgoing->node, outgoing->service, outgoing->error);
+		outgoing_retry(outgoing);
+	}
+}
+
 static void outgoing_resolve(struct outgoing *outgoing) {
 	fprintf(stderr, "O %s: Resolving %s/%s...\n", outgoing->id, outgoing->node, outgoing->service);
-
-	struct addrinfo hints = {
-		.ai_family = AF_UNSPEC,
-		.ai_socktype = SOCK_STREAM,
-	};
-
-	int gai_err = getaddrinfo(outgoing->node, outgoing->service, &hints, &outgoing->addrs);
-	if (gai_err) {
-		fprintf(stderr, "O %s: Failed to resolve %s/%s: %s\n", outgoing->id, outgoing->node, outgoing->service, gai_strerror(gai_err));
-		outgoing_retry(outgoing);
-		return;
-	}
-	outgoing->addr = outgoing->addrs;
-	outgoing_connect_next(outgoing);
+	outgoing->peer.fd = -1;
+	outgoing->peer.event_handler = outgoing_resolve_handler;
+	resolve((struct peer *) outgoing, outgoing->node, outgoing->service, 0, &outgoing->addrs, &outgoing->error);
 }
 
 static void outgoing_resolve_wrapper(struct peer *peer) {

adsbus/resolve.c

@@ -0,0 +1,77 @@
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <fcntl.h>
+#include <netdb.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "peer.h"
+
+#include "resolve.h"
+
+struct resolve {
+	struct peer peer;
+
+	struct addrinfo **addrs;
+	const char **error;
+
+	struct peer *inner_peer;
+
+	struct addrinfo ar_request;
+	struct gaicb gaicb;
+	struct gaicb *requests[1];
+
+	struct sigevent sev;
+};
+
+static void resolve_handler(struct peer *peer) {
+	struct resolve *res = (struct resolve *) peer;
+
+	assert(!close(res->peer.fd));
+
+	int err = gai_error(&res->gaicb);
+	if (err == 0) {
+		*res->addrs = res->gaicb.ar_result;
+		*res->error = NULL;
+	} else {
+		*res->addrs = NULL;
+		*res->error = gai_strerror(err);
+	}
+	struct peer *inner_peer = res->inner_peer;
+	free(res);
+	inner_peer->event_handler(inner_peer);
+}
+
+static void resolve_callback(union sigval val) {
+	assert(!close(val.sival_int));
+}
+
+void resolve(struct peer *peer, const char *node, const char *service, int flags, struct addrinfo **addrs, const char **error) {
+	struct resolve *res = malloc(sizeof(*res));
+	res->addrs = addrs;
+	res->error = error;
+	res->inner_peer = peer;
+
+	int fds[2];
+	assert(!pipe2(fds, O_NONBLOCK));
+	res->peer.fd = fds[0];
+	res->peer.event_handler = resolve_handler;
+	peer_epoll_add((struct peer *) res, EPOLLRDHUP);
+
+	res->requests[0] = &res->gaicb;
+	res->gaicb.ar_name = node;
+	res->gaicb.ar_service = service;
+	res->gaicb.ar_request = &res->ar_request;
+	res->ar_request.ai_family = AF_UNSPEC;
+	res->ar_request.ai_socktype = SOCK_STREAM;
+	res->ar_request.ai_protocol = 0;
+	res->ar_request.ai_flags = AI_V4MAPPED | AI_ADDRCONFIG | flags;
+
+	res->sev.sigev_notify = SIGEV_THREAD;
+	res->sev.sigev_value.sival_int = fds[1];
+	res->sev.sigev_notify_function = resolve_callback;
+	res->sev.sigev_notify_attributes = NULL;
+
+	assert(!getaddrinfo_a(GAI_NOWAIT, res->requests, 1, &res->sev));
+}

adsbus/resolve.h

@@ -0,0 +1,6 @@
+#pragma once
+
+struct peer;
+struct addrinfo;
+
+void resolve(struct peer *, const char *, const char *, int, struct addrinfo **, const char **);