listen: move generic code to server_socket.c

Makefile.am

@@ -111,6 +111,7 @@ mpd_headers = \
 	src/icy_metadata.h \
 	src/client.h \
 	src/client_internal.h \
+	src/server_socket.h \
 	src/listen.h \
 	src/log.h \
 	src/ls.h \
@@ -275,6 +276,7 @@ src_mpd_SOURCES = \
 	src/client_process.c \
 	src/client_read.c \
 	src/client_write.c \
+	src/server_socket.c \
 	src/listen.c \
 	src/log.c \
 	src/ls.c \

src/listen.c

@@ -19,333 +19,44 @@
 
 #include "config.h"
 #include "listen.h"
-#include "socket_util.h"
+#include "server_socket.h"
 #include "client.h"
 #include "conf.h"
-#include "fd_util.h"
 #include "glib_compat.h"
 
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
 #include <string.h>
-#include <errno.h>
-#include <unistd.h>
-#include <stdlib.h>
 #include <assert.h>
 
-#ifdef WIN32
-#define WINVER 0x0501
-#include <ws2tcpip.h>
-#include <winsock.h>
-#else
-#include <netinet/in.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <netdb.h>
-#endif
-
 #undef G_LOG_DOMAIN
 #define G_LOG_DOMAIN "listen"
 
 #define DEFAULT_PORT	6600
 
-struct listen_socket {
-	struct listen_socket *next;
-
-	int fd;
-
-	guint source_id;
-};
-
-static struct listen_socket *listen_sockets;
+static struct server_socket *listen_socket;
 int listen_port;
 
-static GQuark
-listen_quark(void)
-{
-	return g_quark_from_static_string("listen");
-}
-
-static gboolean
-listen_in_event(GIOChannel *source, GIOCondition condition, gpointer data);
-
-static bool
-listen_add_address(int pf, const struct sockaddr *addrp, socklen_t addrlen,
-		   GError **error)
-{
-	char *address_string;
-	int fd;
-	struct listen_socket *ls;
-	GIOChannel *channel;
-
-	address_string = sockaddr_to_string(addrp, addrlen, NULL);
-	if (address_string != NULL) {
-		g_debug("binding to socket address %s", address_string);
-		g_free(address_string);
-	}
-
-	fd = socket_bind_listen(pf, SOCK_STREAM, 0, addrp, addrlen, 5, error);
-	if (fd < 0)
-		return false;
-
-	ls = g_new(struct listen_socket, 1);
-	ls->fd = fd;
-
-	channel = g_io_channel_unix_new(fd);
-	ls->source_id = g_io_add_watch(channel, G_IO_IN,
-				       listen_in_event, GINT_TO_POINTER(fd));
-	g_io_channel_unref(channel);
-
-	ls->next = listen_sockets;
-	listen_sockets = ls;
-
-	return true;
-}
-
-#ifdef HAVE_TCP
-
-/**
- * Add a listener on a port on all IPv4 interfaces.
- *
- * @param port the TCP port
- * @param error location to store the error occuring, or NULL to ignore errors
- * @return true on success
- */
-static bool
-listen_add_port_ipv4(unsigned int port, GError **error)
-{
-	struct sockaddr_in sin;
-	const struct sockaddr *addrp = (const struct sockaddr *)&sin;
-	socklen_t addrlen = sizeof(sin);
-
-	memset(&sin, 0, sizeof(sin));
-	sin.sin_port = htons(port);
-	sin.sin_family = AF_INET;
-	sin.sin_addr.s_addr = INADDR_ANY;
-
-	return listen_add_address(PF_INET, addrp, addrlen, error);
-}
-
-#ifdef HAVE_IPV6
-/**
- * Add a listener on a port on all IPv6 interfaces.
- *
- * @param port the TCP port
- * @param error location to store the error occuring, or NULL to ignore errors
- * @return true on success
- */
-static bool
-listen_add_port_ipv6(unsigned int port, GError **error)
+static void
+listen_callback(int fd, const struct sockaddr *address,
+		size_t address_length, int uid, G_GNUC_UNUSED void *ctx)
 {
-	struct sockaddr_in6 sin;
-	const struct sockaddr *addrp = (const struct sockaddr *)&sin;
-	socklen_t addrlen = sizeof(sin);
-
-	memset(&sin, 0, sizeof(sin));
-	sin.sin6_port = htons(port);
-	sin.sin6_family = AF_INET6;
-
-	return listen_add_address(PF_INET6, addrp, addrlen, error);
+	client_new(fd, address, address_length, uid);
 }
-#endif /* HAVE_IPV6 */
-
-#endif /* HAVE_TCP */
-
-/**
- * Add a listener on a port on all interfaces.
- *
- * @param port the TCP port
- * @param error location to store the error occuring, or NULL to ignore errors
- * @return true on success
- */
-static bool
-listen_add_port(unsigned int port, GError **error)
-{
-#ifdef HAVE_TCP
-	bool success;
-#ifdef HAVE_IPV6
-	bool success6;
-	GError *error2 = NULL;
-#endif
-
-	g_debug("binding to any address");
-
-#ifdef HAVE_IPV6
-	success6 = listen_add_port_ipv6(port, &error2);
-	if (!success6) {
-		if (error2->domain != listen_quark() ||
-		    (error2->code != EAFNOSUPPORT && error2->code != EINVAL &&
-		     error2->code != EPROTONOSUPPORT)) {
-			g_propagate_error(error, error2);
-			return false;
-		}
-
-		/* although MPD was compiled with IPv6 support, this
-		   host does not have it - ignore this error */
-		g_error_free(error2);
-	}
-#endif
-
-	success = listen_add_port_ipv4(port, error);
-	if (!success) {
-#ifdef HAVE_IPV6
-		if (success6)
-			/* non-critical: IPv6 listener is
-			   already set up */
-			g_clear_error(error);
-		else
-#endif
-			return false;
-	}
-
-	return true;
-#else /* HAVE_TCP */
-	(void)port;
-
-	g_set_error(error, listen_quark(), 0,
-		    "TCP support is disabled");
-	return false;
-#endif /* HAVE_TCP */
-}
-
-/**
- * Resolves a host name, and adds listeners on all addresses in the
- * result set.
- *
- * @param hostname the host name to be resolved
- * @param port the TCP port
- * @param error location to store the error occuring, or NULL to ignore errors
- * @return true on success
- */
-static bool
-listen_add_host(const char *hostname, unsigned port, GError **error_r)
-{
-#ifdef HAVE_TCP
-	struct addrinfo hints, *ai, *i;
-	char service[20];
-	int ret;
-	bool success;
-
-	g_debug("binding to address for %s", hostname);
-
-	memset(&hints, 0, sizeof(hints));
-	hints.ai_flags = AI_PASSIVE;
-#ifdef AI_ADDRCONFIG
-	hints.ai_flags |= AI_ADDRCONFIG;
-#endif
-	hints.ai_family = PF_UNSPEC;
-	hints.ai_socktype = SOCK_STREAM;
-	hints.ai_protocol = IPPROTO_TCP;
-
-	g_snprintf(service, sizeof(service), "%u", port);
-
-	ret = getaddrinfo(hostname, service, &hints, &ai);
-	if (ret != 0) {
-		g_set_error(error_r, listen_quark(), ret,
-			    "Failed to look up host \"%s\": %s",
-			    hostname, gai_strerror(ret));
-		return false;
-	}
-
-	for (i = ai; i != NULL; i = i->ai_next) {
-		GError *error = NULL;
-
-		success = listen_add_address(i->ai_family, i->ai_addr,
-					     i->ai_addrlen, &error);
-		if (!success) {
-			if (i == ai) {
-				/* first bind has failed: fatal
-				   error */
-				g_propagate_error(error_r, error);
-				return false;
-			} else {
-				char *address_string =
-					sockaddr_to_string(i->ai_addr,
-							   i->ai_addrlen,
-							   NULL);
-				if (address_string == NULL)
-					address_string = g_strdup("[unknown]");
-
-				g_warning("bind to %s failed: %s "
-					  "(continuing anyway, because at "
-					  "least one address is bound)",
-					  address_string, error->message);
-				g_free(address_string);
-				g_error_free(error);
-			}
-		}
-	}
-
-	freeaddrinfo(ai);
-
-	return true;
-#else /* HAVE_TCP */
-
-	(void)hostname;
-	(void)port;
-
-	g_set_error(error_r, listen_quark(), 0,
-		    "TCP support is disabled");
-	return false;
-#endif /* HAVE_TCP */
-}
-
-#ifdef HAVE_UN
-/**
- * Add a listener on a Unix domain socket.
- *
- * @param path the absolute socket path
- * @param error location to store the error occuring, or NULL to ignore errors
- * @return true on success
- */
-static bool
-listen_add_path(const char *path, GError **error)
-{
-	size_t path_length;
-	struct sockaddr_un s_un;
-	const struct sockaddr *addrp = (const struct sockaddr *)&s_un;
-	socklen_t addrlen = sizeof(s_un);
-	bool success;
-
-	path_length = strlen(path);
-	if (path_length >= sizeof(s_un.sun_path)) {
-		g_set_error(error, listen_quark(), 0,
-			    "unix socket path is too long");
-		return false;
-	}
-
-	unlink(path);
-
-	s_un.sun_family = AF_UNIX;
-	memcpy(s_un.sun_path, path, path_length + 1);
-
-	success = listen_add_address(PF_UNIX, addrp, addrlen, error);
-	if (!success)
-		return false;
-
-	/* allow everybody to connect */
-	chmod(path, 0666);
-
-	return true;
-}
-#endif /* HAVE_UN */
 
 static bool
 listen_add_config_param(unsigned int port,
 			const struct config_param *param,
-			GError **error)
+			GError **error_r)
 {
 	assert(param != NULL);
 
 	if (0 == strcmp(param->value, "any")) {
-		return listen_add_port(port, error);
-#ifdef HAVE_UN
+		return server_socket_add_port(listen_socket, port, error_r);
 	} else if (param->value[0] == '/') {
-		return listen_add_path(param->value, error);
-#endif /* HAVE_UN */
+		return server_socket_add_path(listen_socket, param->value,
+					      error_r);
 	} else {
-		return listen_add_host(param->value, port, error);
+		return server_socket_add_host(listen_socket, param->value,
+					      port, error_r);
 	}
 }
 
@@ -358,6 +69,8 @@ listen_global_init(GError **error_r)
 	bool success;
 	GError *error = NULL;
 
+	listen_socket = server_socket_new(listen_callback, NULL);
+
 	if (param != NULL) {
 		/* "bind_to_address" is configured, create listeners
 		   for all values */
@@ -378,7 +91,7 @@ listen_global_init(GError **error_r)
 		/* no "bind_to_address" configured, bind the
 		   configured port on all interfaces */
 
-		success = listen_add_port(port, &error);
+		success = server_socket_add_port(listen_socket, port, error_r);
 		if (!success) {
 			g_propagate_prefixed_error(error_r, error,
 						   "Failed to listen on *:%d: ",
@@ -387,6 +100,9 @@ listen_global_init(GError **error_r)
 		}
 	}
 
+	if (!server_socket_open(listen_socket, error_r))
+		return false;
+
 	listen_port = port;
 	return true;
 }
@@ -395,57 +111,7 @@ void listen_global_finish(void)
 {
 	g_debug("listen_global_finish called");
 
-	while (listen_sockets != NULL) {
-		struct listen_socket *ls = listen_sockets;
-		listen_sockets = ls->next;
+	assert(listen_socket != NULL);
 
-		g_source_remove(ls->source_id);
-		close(ls->fd);
-		g_free(ls);
-	}
-}
-
-static int get_remote_uid(int fd)
-{
-#ifdef HAVE_STRUCT_UCRED
-	struct ucred cred;
-	socklen_t len = sizeof (cred);
-
-	if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len) < 0)
-		return 0;
-
-	return cred.uid;
-#else
-#ifdef HAVE_GETPEEREID
-	uid_t euid;
-	gid_t egid;
-
-	if (getpeereid(fd, &euid, &egid) == 0)
-		return euid;
-#else
-	(void)fd;
-#endif
-	return -1;
-#endif
-}
-
-static gboolean
-listen_in_event(G_GNUC_UNUSED GIOChannel *source,
-		G_GNUC_UNUSED GIOCondition condition,
-		gpointer data)
-{
-	int listen_fd = GPOINTER_TO_INT(data), fd;
-	struct sockaddr_storage sa;
-	size_t sa_length = sizeof(sa);
-
-	fd = accept_cloexec_nonblock(listen_fd, (struct sockaddr*)&sa,
-				     &sa_length);
-	if (fd >= 0) {
-		client_new(fd, (struct sockaddr*)&sa, sa_length,
-			   get_remote_uid(fd));
-	} else if (fd < 0 && errno != EINTR) {
-		g_warning("Problems accept()'ing");
-	}
-
-	return true;
+	server_socket_free(listen_socket);
 }

src/server_socket.c

+/*
+ * Copyright (C) 2003-2010 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "server_socket.h"
+#include "socket_util.h"
+#include "fd_util.h"
+#include "glib_compat.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#ifdef WIN32
+#define WINVER 0x0501
+#include <ws2tcpip.h>
+#include <winsock.h>
+#else
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <netdb.h>
+#endif
+
+#undef G_LOG_DOMAIN
+#define G_LOG_DOMAIN "listen"
+
+#define DEFAULT_PORT	6600
+
+struct one_socket {
+	struct one_socket *next;
+	struct server_socket *parent;
+
+	unsigned serial;
+
+	int fd;
+	guint source_id;
+
+	char *path;
+
+	size_t address_length;
+	struct sockaddr address;
+};
+
+struct server_socket {
+	server_socket_callback_t callback;
+	void *callback_ctx;
+
+	struct one_socket *sockets, **sockets_tail_r;
+	unsigned next_serial;
+};
+
+static GQuark
+server_socket_quark(void)
+{
+	return g_quark_from_static_string("server_socket");
+}
+
+struct server_socket *
+server_socket_new(server_socket_callback_t callback, void *callback_ctx)
+{
+	struct server_socket *ss = g_new(struct server_socket, 1);
+	ss->callback = callback;
+	ss->callback_ctx = callback_ctx;
+	ss->sockets = NULL;
+	ss->sockets_tail_r = &ss->sockets;
+	ss->next_serial = 1;
+	return ss;
+}
+
+void
+server_socket_free(struct server_socket *ss)
+{
+	server_socket_close(ss);
+
+	while (ss->sockets != NULL) {
+		struct one_socket *s = ss->sockets;
+		ss->sockets = s->next;
+
+		assert(s->fd < 0);
+
+		g_free(s->path);
+		g_free(s);
+	}
+
+	g_free(ss);
+}
+
+/**
+ * Wraper for sockaddr_to_string() which never fails.
+ */
+static char *
+one_socket_to_string(const struct one_socket *s)
+{
+	char *p = sockaddr_to_string(&s->address, s->address_length, NULL);
+	if (p == NULL)
+		p = g_strdup("[unknown]");
+	return p;
+}
+
+static int
+get_remote_uid(int fd)
+{
+#ifdef HAVE_STRUCT_UCRED
+	struct ucred cred;
+	socklen_t len = sizeof (cred);
+
+	if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cred, &len) < 0)
+		return 0;
+
+	return cred.uid;
+#else
+#ifdef HAVE_GETPEEREID
+	uid_t euid;
+	gid_t egid;
+
+	if (getpeereid(fd, &euid, &egid) == 0)
+		return euid;
+#else
+	(void)fd;
+#endif
+	return -1;
+#endif
+}
+
+static gboolean
+server_socket_in_event(G_GNUC_UNUSED GIOChannel *source,
+		       G_GNUC_UNUSED GIOCondition condition,
+		       gpointer data)
+{
+	struct one_socket *s = data;
+
+	struct sockaddr_storage address;
+	size_t address_length = sizeof(address);
+	int fd = accept_cloexec_nonblock(s->fd, (struct sockaddr*)&address,
+					 &address_length);
+	if (fd >= 0)
+		s->parent->callback(fd, (const struct sockaddr*)&address,
+				    address_length, get_remote_uid(fd),
+				    s->parent->callback_ctx);
+	else
+		g_warning("accept() failed: %s", g_strerror(errno));
+
+	return true;
+}
+
+bool
+server_socket_open(struct server_socket *ss, GError **error_r)
+{
+	struct one_socket *good = NULL, *bad = NULL;
+	GError *last_error = NULL;
+
+	for (struct one_socket *s = ss->sockets; s != NULL; s = s->next) {
+		assert(s->serial > 0);
+		assert(good == NULL || s->serial >= good->serial);
+		assert(s->fd < 0);
+
+		if (bad != NULL && s->serial != bad->serial) {
+			server_socket_close(ss);
+			g_propagate_error(error_r, last_error);
+			return false;
+		}
+
+		GError *error = NULL;
+		s->fd = socket_bind_listen(s->address.sa_family, SOCK_STREAM, 0,
+					   &s->address, s->address_length, 5,
+					   &error);
+		if (s->fd < 0) {
+			if (good != NULL && good->serial == s->serial) {
+				char *address_string = one_socket_to_string(s);
+				char *good_string = one_socket_to_string(good);
+				g_warning("bind to '%s' failed: %s "
+					  "(continuing anyway, because "
+					  "binding to '%s' succeeded)",
+					  address_string, error->message,
+					  good_string);
+				g_free(address_string);
+				g_free(good_string);
+				g_error_free(error);
+			} else if (bad == NULL) {
+				bad = s;
+
+				char *address_string = one_socket_to_string(s);
+				g_propagate_prefixed_error(&last_error, error,
+							   "Failed to bind to '%s': ",
+							   address_string);
+				g_free(address_string);
+			} else
+				g_error_free(error);
+			continue;
+		}
+
+		/* allow everybody to connect */
+
+		if (s->path != NULL)
+			chmod(s->path, 0666);
+
+		/* register in the GLib main loop */
+
+		GIOChannel *channel = g_io_channel_unix_new(s->fd);
+		s->source_id = g_io_add_watch(channel, G_IO_IN,
+					      server_socket_in_event, s);
+		g_io_channel_unref(channel);
+
+		/* mark this socket as "good", and clear previous
+		   errors */
+
+		good = s;
+
+		if (bad != NULL) {
+			bad = NULL;
+			g_error_free(last_error);
+			last_error = NULL;
+		}
+	}
+
+	if (bad != NULL) {
+		server_socket_close(ss);
+		g_propagate_error(error_r, last_error);
+		return false;
+	}
+
+	return true;
+}
+
+void
+server_socket_close(struct server_socket *ss)
+{
+	for (struct one_socket *s = ss->sockets; s != NULL; s = s->next) {
+		if (s->fd < 0)
+			continue;
+
+		g_source_remove(s->source_id);
+		close(s->fd);
+		s->fd = -1;
+	}
+}
+
+static struct one_socket *
+one_socket_new(unsigned serial, const struct sockaddr *address,
+	       size_t address_length)
+{
+	assert(address != NULL);
+	assert(address_length > 0);
+
+	struct one_socket *s = g_malloc(sizeof(*s) - sizeof(s->address) +
+					address_length);
+	s->next = NULL;
+	s->serial = serial;
+	s->fd = -1;
+	s->path = NULL;
+	s->address_length = address_length;
+	memcpy(&s->address, address, address_length);
+
+	return s;
+}
+
+static struct one_socket *
+server_socket_add_address(struct server_socket *ss,
+			  const struct sockaddr *address,
+			  size_t address_length)
+{
+	assert(ss != NULL);
+	assert(ss->sockets_tail_r != NULL);
+	assert(*ss->sockets_tail_r == NULL);
+
+	struct one_socket *s = one_socket_new(ss->next_serial,
+					      address, address_length);
+	s->parent = ss;
+	*ss->sockets_tail_r = s;
+	ss->sockets_tail_r = &s->next;
+
+	return s;
+}
+
+#ifdef HAVE_TCP
+
+/**
+ * Add a listener on a port on all IPv4 interfaces.
+ *
+ * @param port the TCP port
+ */
+static void
+server_socket_add_port_ipv4(struct server_socket *ss, unsigned port)
+{
+	struct sockaddr_in sin;
+	memset(&sin, 0, sizeof(sin));
+	sin.sin_port = htons(port);
+	sin.sin_family = AF_INET;
+	sin.sin_addr.s_addr = INADDR_ANY;
+
+	server_socket_add_address(ss, (const struct sockaddr *)&sin,
+				  sizeof(sin));
+}
+
+#ifdef HAVE_IPV6
+/**
+ * Add a listener on a port on all IPv6 interfaces.
+ *
+ * @param port the TCP port
+ */
+static void
+server_socket_add_port_ipv6(struct server_socket *ss, unsigned port)
+{
+	struct sockaddr_in6 sin;
+	memset(&sin, 0, sizeof(sin));
+	sin.sin6_port = htons(port);
+	sin.sin6_family = AF_INET6;
+
+	server_socket_add_address(ss, (const struct sockaddr *)&sin,
+				  sizeof(sin));
+}
+#endif /* HAVE_IPV6 */
+
+#endif /* HAVE_TCP */
+
+bool
+server_socket_add_port(struct server_socket *ss, unsigned port,
+		       GError **error_r)
+{
+#ifdef HAVE_TCP
+	if (port == 0 || port > 0xffff) {
+		g_set_error(error_r, server_socket_quark(), 0,
+			    "Invalid TCP port");
+		return false;
+	}
+
+#ifdef HAVE_IPV6
+	server_socket_add_port_ipv6(ss, port);
+#endif
+	server_socket_add_port_ipv4(ss, port);
+
+	++ss->next_serial;
+
+	return true;
+#else /* HAVE_TCP */
+	(void)ss;
+	(void)port;
+
+	g_set_error(error_r, server_socket_quark(), 0,
+		    "TCP support is disabled");
+	return false;
+#endif /* HAVE_TCP */
+}
+
+bool
+server_socket_add_host(struct server_socket *ss, const char *hostname,
+		       unsigned port, GError **error_r)
+{
+#ifdef HAVE_TCP
+	struct addrinfo hints;
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_flags = AI_PASSIVE;
+#ifdef AI_ADDRCONFIG
+	hints.ai_flags |= AI_ADDRCONFIG;
+#endif
+	hints.ai_family = PF_UNSPEC;
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_protocol = IPPROTO_TCP;
+
+	char service[20];
+	g_snprintf(service, sizeof(service), "%u", port);
+
+	struct addrinfo *ai;
+	int ret = getaddrinfo(hostname, service, &hints, &ai);
+	if (ret != 0) {
+		g_set_error(error_r, server_socket_quark(), ret,
+			    "Failed to look up host \"%s\": %s",
+			    hostname, gai_strerror(ret));
+		return false;
+	}
+
+	for (const struct addrinfo *i = ai; i != NULL; i = i->ai_next)
+		server_socket_add_address(ss, i->ai_addr, i->ai_addrlen);
+
+	freeaddrinfo(ai);
+
+	++ss->next_serial;
+
+	return true;
+#else /* HAVE_TCP */
+	(void)ss;
+	(void)hostname;
+	(void)port;
+
+	g_set_error(error_r, server_socket_quark(), 0,
+		    "TCP support is disabled");
+	return false;
+#endif /* HAVE_TCP */
+}
+
+bool
+server_socket_add_path(struct server_socket *ss, const char *path,
+		       GError **error_r)
+{
+#ifdef HAVE_UN
+	struct sockaddr_un s_un;
+
+	size_t path_length = strlen(path);
+	if (path_length >= sizeof(s_un.sun_path)) {
+		g_set_error(error_r, server_socket_quark(), 0,
+			    "UNIX socket path is too long");
+		return false;
+	}
+
+	unlink(path);
+
+	s_un.sun_family = AF_UNIX;
+	memcpy(s_un.sun_path, path, path_length + 1);
+
+	struct one_socket *s =
+		server_socket_add_address(ss, (const struct sockaddr *)&s_un,
+					  sizeof(s_un));
+	s->path = g_strdup(path);
+
+	return true;
+#else /* !HAVE_UN */
+	(void)ss;
+	(void)path;
+
+	g_set_error(error_r, server_socket_quark(), 0,
+		    "UNIX domain socket support is disabled");
+	return false;
+#endif /* !HAVE_UN */
+}
+

src/server_socket.h

+/*
+ * Copyright (C) 2003-2010 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_SERVER_SOCKET_H
+#define MPD_SERVER_SOCKET_H
+
+#include <stdbool.h>
+
+#include <glib.h>
+
+struct sockaddr;
+
+typedef void (*server_socket_callback_t)(int fd,
+					 const struct sockaddr *address,
+					 size_t address_length, int uid,
+					 void *ctx);
+
+struct server_socket *
+server_socket_new(server_socket_callback_t callback, void *callback_ctx);
+
+void
+server_socket_free(struct server_socket *ss);
+
+bool
+server_socket_open(struct server_socket *ss, GError **error_r);
+
+void
+server_socket_close(struct server_socket *ss);
+
+/**
+ * Add a listener on a port on all interfaces.
+ *
+ * @param port the TCP port
+ * @param error_r location to store the error occuring, or NULL to
+ * ignore errors
+ * @return true on success
+ */
+bool
+server_socket_add_port(struct server_socket *ss, unsigned port,
+		       GError **error_r);
+
+/**
+ * Resolves a host name, and adds listeners on all addresses in the
+ * result set.
+ *
+ * @param hostname the host name to be resolved
+ * @param port the TCP port
+ * @param error_r location to store the error occuring, or NULL to
+ * ignore errors
+ * @return true on success
+ */
+bool
+server_socket_add_host(struct server_socket *ss, const char *hostname,
+		       unsigned port, GError **error_r);
+
+/**
+ * Add a listener on a Unix domain socket.
+ *
+ * @param path the absolute socket path
+ * @param error_r location to store the error occuring, or NULL to
+ * ignore errors
+ * @return true on success
+ */
+bool
+server_socket_add_path(struct server_socket *ss, const char *path,
+		       GError **error_r);
+
+#endif