Split out generic resolver functions.

adsbus/Makefile

@@ -13,7 +13,7 @@ ADSBUS_TEST_FLAGS ?= --stdin --stdout=airspy_adsb --stdout=beast --stdout=json -
 OBJ_TRANSPORT = exec.o file.o incoming.o outgoing.o
 OBJ_FLOW = flow.o receive.o send.o
 OBJ_PROTOCOL = airspy_adsb.o beast.o json.o proto.o raw.o stats.o
-OBJ_UTIL = buf.o hex.o list.o opts.o packet.o peer.o rand.o resolve.o server.o socket.o uuid.o wakeup.o
+OBJ_UTIL = asyncaddrinfo.o buf.o hex.o list.o opts.o packet.o peer.o rand.o resolve.o server.o socket.o uuid.o wakeup.o
 OBJ_PROTO = adsb.pb-c.o
 
 all: adsbus

adsbus/asyncaddrinfo.c

@@ -0,0 +1,125 @@
+#include <assert.h>
+#include <netdb.h>
+#include <pthread.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#include "asyncaddrinfo.h"
+
+struct asyncaddrinfo_resolution {
+	int return_fd;
+
+	char *node;
+	char *service;
+	struct addrinfo _hints, *hints;
+
+	int err;
+	struct addrinfo *addrs;
+};
+
+static size_t asyncaddrinfo_num_threads;
+static pthread_t *asyncaddrinfo_threads = NULL;
+static int asyncaddrinfo_write_fd;
+
+static void *asyncaddrinfo_main(void *arg) {
+	int fd = (int) (intptr_t) arg;
+	struct asyncaddrinfo_resolution *res;
+	ssize_t len;
+	while ((len = recv(fd, &res, sizeof(res), 0)) == sizeof(res)) {
+		res->err = getaddrinfo(res->node, res->service, res->hints, &res->addrs);
+		int return_fd = res->return_fd;
+		res->return_fd = -1;
+		assert(send(return_fd, &res, sizeof(res), MSG_EOR) == sizeof(res));
+		// Main thread now owns res
+		assert(!close(return_fd));
+	}
+	assert(!len);
+	assert(!close(fd));
+	return NULL;
+}
+
+static void asyncaddrinfo_del(struct asyncaddrinfo_resolution *res) {
+	if (res->node) {
+		free(res->node);
+		res->node = NULL;
+	}
+	if (res->service) {
+		free(res->service);
+		res->service = NULL;
+	}
+	free(res);
+}
+
+void asyncaddrinfo_init(size_t threads) {
+	assert(!asyncaddrinfo_threads);
+
+	int fds[2];
+	assert(!socketpair(AF_UNIX, SOCK_SEQPACKET | SOCK_CLOEXEC, 0, fds));
+	asyncaddrinfo_write_fd = fds[1];
+
+	asyncaddrinfo_num_threads = threads;
+	asyncaddrinfo_threads = malloc(asyncaddrinfo_num_threads * sizeof(*asyncaddrinfo_threads));
+	assert(asyncaddrinfo_threads);
+
+	for (size_t i = 0; i < asyncaddrinfo_num_threads; i++) {
+		int subfd = dup(fds[0]);
+		assert(subfd >= 0);
+		assert(!pthread_create(&asyncaddrinfo_threads[i], NULL, asyncaddrinfo_main, (void *) (intptr_t) subfd));
+	}
+	assert(!close(fds[0]));
+}
+
+void asyncaddrinfo_cleanup() {
+	assert(asyncaddrinfo_threads);
+	assert(!close(asyncaddrinfo_write_fd));
+	asyncaddrinfo_write_fd = -1;
+	for (size_t i = 0; i < asyncaddrinfo_num_threads; i++) {
+		assert(!pthread_join(asyncaddrinfo_threads[i], NULL));
+	}
+	free(asyncaddrinfo_threads);
+	asyncaddrinfo_threads = NULL;
+}
+
+int asyncaddrinfo_resolve(const char *node, const char *service, struct addrinfo *hints) {
+	int fds[2];
+	assert(!socketpair(AF_UNIX, SOCK_SEQPACKET | SOCK_CLOEXEC, 0, fds));
+
+	struct asyncaddrinfo_resolution *res = malloc(sizeof(*res));
+	assert(res);
+	res->return_fd = fds[1];
+	if (node) {
+		res->node = strdup(node);
+		assert(res->node);
+	} else {
+		res->node = NULL;
+	}
+	if (service) {
+		res->service = strdup(service);
+		assert(res->service);
+	} else {
+		res->service = NULL;
+	}
+	if (hints) {
+		memcpy(&res->_hints, hints, sizeof(res->_hints));
+		res->hints = &res->_hints;
+	} else {
+		res->hints = NULL;
+	}
+	assert(send(asyncaddrinfo_write_fd, &res, sizeof(res), MSG_EOR) == sizeof(res));
+	// Resolve thread now owns res
+
+	return fds[0];
+}
+
+int asyncaddrinfo_result(int fd, struct addrinfo **addrs) {
+	struct asyncaddrinfo_resolution *res;
+	assert(recv(fd, &res, sizeof(res), 0) == sizeof(res));
+	assert(!close(fd));
+	*addrs = res->addrs;
+	int err = res->err;
+	asyncaddrinfo_del(res);
+	return err;
+}

adsbus/asyncaddrinfo.h

@@ -0,0 +1,8 @@
+#pragma once
+
+struct addrinfo;
+
+void asyncaddrinfo_init(size_t threads);
+void asyncaddrinfo_cleanup(void);
+int asyncaddrinfo_resolve(const char *node, const char *service, struct addrinfo *hints);
+int asyncaddrinfo_result(int fd, struct addrinfo **addrs);

adsbus/resolve.c

@@ -1,86 +1,33 @@
-#include <assert.h>
-#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/socket.h>
 #include <netdb.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <pthread.h>
 
+#include "asyncaddrinfo.h"
 #include "peer.h"
 
 #include "resolve.h"
 
-struct resolve {
-	int fd;
-
-	char *node;
-	char *service;
-	int flags;
-
-	int err;
-	struct addrinfo *addrs;
-};
-
-static pthread_t resolve_thread;
-static int resolve_write_fd;
-
-static void *resolve_main(void *arg) {
-	int fd = (int) (intptr_t) arg;
-	struct resolve *res;
-	ssize_t len;
-	while ((len = read(fd, &res, sizeof(res))) == sizeof(res)) {
-		struct addrinfo hints = {
-			.ai_family = AF_UNSPEC,
-			.ai_socktype = SOCK_STREAM,
-			.ai_flags = AI_V4MAPPED | AI_ADDRCONFIG | res->flags,
-		};
-		res->err = getaddrinfo(res->node, res->service, &hints, &res->addrs);
-		free(res->node);
-		free(res->service);
-		res->node = res->service = NULL;
-		assert(write(res->fd, &res, sizeof(res)) == sizeof(res));
-		close(res->fd);
-		res->fd = -1;
-	}
-	assert(!len);
-	assert(!close(fd));
-	return NULL;
-}
-
 void resolve_init() {
-	int fds[2];
-	assert(!pipe2(fds, O_CLOEXEC));
-	resolve_write_fd = fds[1];
-	assert(!pthread_create(&resolve_thread, NULL, resolve_main, (void *) (intptr_t) fds[0]));
+	asyncaddrinfo_init(2);
 }
 
 void resolve_cleanup() {
-	assert(!close(resolve_write_fd));
-	assert(!pthread_join(resolve_thread, NULL));
+	asyncaddrinfo_cleanup();
 }
 
 void resolve(struct peer *peer, const char *node, const char *service, int flags) {
-	int fds[2];
-	assert(!pipe2(fds, O_CLOEXEC));
+	struct addrinfo hints = {
+		.ai_flags = AI_V4MAPPED | AI_ADDRCONFIG | flags,
+		.ai_family = AF_UNSPEC,
+		.ai_socktype = SOCK_STREAM,
+	};
 
-	struct resolve *res = malloc(sizeof(*res));
-	res->fd = fds[1];
-	res->node = strdup(node);
-	res->service = strdup(service);
-	res->flags = flags;
-	assert(write(resolve_write_fd, &res, sizeof(res)) == sizeof(res));
-
-	peer->fd = fds[0];
+	peer->fd = asyncaddrinfo_resolve(node, service, &hints);
 	peer_epoll_add(peer, EPOLLIN);
 }
 
 int resolve_result(struct peer *peer, struct addrinfo **addrs) {
-	struct resolve *res;
-	assert(read(peer->fd, &res, sizeof(res)) == sizeof(res));
-	assert(!close(peer->fd));
+	int err = asyncaddrinfo_result(peer->fd, addrs);
 	peer->fd = -1;
-	*addrs = res->addrs;
-	int err = res->err;
-	free(res);
 	return err;
 }