/*
 * Copyright (C) 2003-2009 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 "listen.h"
#include "socket_util.h"
#include "client.h"
#include "conf.h"
#include "fd_util.h"
#include "glib_compat.h"
#include "config.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
#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;
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)
{
	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);
}
#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)
{
	assert(param != NULL);

	if (0 == strcmp(param->value, "any")) {
		return listen_add_port(port, error);
#ifdef HAVE_UN
	} else if (param->value[0] == '/') {
		return listen_add_path(param->value, error);
#endif /* HAVE_UN */
	} else {
		return listen_add_host(param->value, port, error);
	}
}

bool
listen_global_init(GError **error_r)
{
	int port = config_get_positive(CONF_PORT, DEFAULT_PORT);
	const struct config_param *param =
		config_get_next_param(CONF_BIND_TO_ADDRESS, NULL);
	bool success;
	GError *error = NULL;

	if (param != NULL) {
		/* "bind_to_address" is configured, create listeners
		   for all values */

		do {
			success = listen_add_config_param(port, param, &error);
			if (!success) {
				g_propagate_prefixed_error(error_r, error,
							   "Failed to listen on %s (line %i): ",
							   param->value, param->line);
				return false;
			}

			param = config_get_next_param(CONF_BIND_TO_ADDRESS,
						      param);
		} while (param != NULL);
	} else {
		/* no "bind_to_address" configured, bind the
		   configured port on all interfaces */

		success = listen_add_port(port, &error);
		if (!success) {
			g_propagate_prefixed_error(error_r, error,
						   "Failed to listen on *:%d: ",
						   port);
			return false;
		}
	}

	listen_port = port;
	return true;
}

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;

		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
	(void)fd;
	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;
}