pipewire/src/modules/module-rtp-session.c

/* PipeWire */
/* SPDX-FileCopyrightText: Copyright © 2022 Wim Taymans <wim.taymans@gmail.com> */
/* SPDX-License-Identifier: MIT */

#include "config.h"

#include <limits.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/in.h>
#include <net/if.h>
#include <ctype.h>

#include <spa/utils/hook.h>
#include <spa/utils/result.h>
#include <spa/utils/ringbuffer.h>
#include <spa/utils/json.h>
#include <spa/param/audio/format-utils.h>
#include <spa/debug/types.h>
#include <spa/debug/mem.h>
#include <spa/debug/log.h>

#include <pipewire/pipewire.h>
#include <pipewire/impl.h>

#include <avahi-client/publish.h>
#include <avahi-client/lookup.h>
#include <avahi-common/error.h>
#include <avahi-common/malloc.h>

#include "module-zeroconf-discover/avahi-poll.h"

#include <module-rtp/rtp.h>
#include <module-rtp/apple-midi.h>
#include <module-rtp/stream.h>
#include "network-utils.h"

/** \page page_module_rtp_session RTP session
 *
 * The `rtp-session` module creates a media session that is announced
 * with avahi/mDNS/Bonjour.
 *
 * Other machines on the network that run a compatible session will see
 * each other and will be able to send audio/midi between each other.
 *
 * The session setup is based on apple-midi and is compatible with
 * apple-midi when the session is using midi.
 *
 * ## Module Name
 *
 * `libpipewire-module-rtp-session`
 *
 * ## Module Options
 *
 * Options specific to the behavior of this module
 *
 * - `local.ifname = <str>`: interface name to use
 * - `control.ip =<str>`: control IP address, default "0.0.0.0"
 * - `control.port =<int>`: control port, default "0"
 * - `net.mtu = <int>`: MTU to use, default 1280
 * - `net.ttl = <int>`: TTL to use, default 1
 * - `net.loop = <bool>`: loopback multicast, default false
 *   `sess.discover-local`: discover local services as well, default false
 * - `sess.min-ptime = <int>`: minimum packet time in milliseconds, default 2
 * - `sess.max-ptime = <int>`: maximum packet time in milliseconds, default 20
 * - `sess.latency.msec = <int>`: receiver latency in milliseconds, default 100
 * - `sess.name = <str>`: a session name
 * - `sess.ts-offset = <int>`: an offset to apply to the timestamp, default -1 = random offset
 * - `sess.ts-refclk = <string>`: the name of a reference clock
 * - `sess.media = <string>`: the media type audio|midi|opus, default midi
 * - `stream.props = {}`: properties to be passed to the stream
 *
 * ## General options
 *
 * Options with well-known behavior:
 *
 * - \ref PW_KEY_REMOTE_NAME
 * - \ref PW_KEY_AUDIO_FORMAT
 * - \ref PW_KEY_AUDIO_RATE
 * - \ref PW_KEY_AUDIO_CHANNELS
 * - \ref SPA_KEY_AUDIO_POSITION
 * - \ref PW_KEY_NODE_NAME
 * - \ref PW_KEY_NODE_DESCRIPTION
 * - \ref PW_KEY_MEDIA_NAME
 * - \ref PW_KEY_NODE_GROUP
 * - \ref PW_KEY_NODE_LATENCY
 * - \ref PW_KEY_NODE_VIRTUAL
 * - \ref PW_KEY_MEDIA_CLASS
 *
 * ## Example configuration
 *\code{.unparsed}
 * # ~/.config/pipewire/pipewire.conf.d/my-rtp-session.conf
 *
 * context.modules = [
 * {   name = libpipewire-module-rtp-session
 *     args = {
 *         #local.ifname = "eth0"
 *         #control.ip = "0.0.0.0"
 *         #control.port = 0
 *         #net.mtu = 1280
 *         #net.ttl = 1
 *         #net.loop = false
 *         #sess.discover-local = false
 *         #sess.min-ptime = 2
 *         #sess.max-ptime = 20
 *         #sess.name = "PipeWire RTP stream"
 *         #sess.media = "audio"
 *         stream.props = {
 *             node.name = "rtp-sink"
 *             #audio.format = "S16BE"
 *             #audio.rate = 48000
 *             #audio.channels = 2
 *             #audio.position = [ FL FR ]
 *         }
 *     }
 *}
 *]
 *\endcode
 *
 * \since 0.3.60
 */

#define NAME "rtp-session"

PW_LOG_TOPIC(mod_topic, "mod." NAME);
#define PW_LOG_TOPIC_DEFAULT mod_topic

#define DEFAULT_CONTROL_IP	"0.0.0.0"
#define DEFAULT_CONTROL_PORT	0
#define DEFAULT_TTL		1
#define DEFAULT_LOOP		false

#define USAGE	"( control.ip=<destination IP address, default:"DEFAULT_CONTROL_IP"> ) "	\
		"( control.port=<int, default:"SPA_STRINGIFY(DEFAULT_CONTROL_PORT)"> ) "	\
		"( local.ifname=<local interface name to use> ) "				\
		"( net.mtu=<desired MTU, default:"SPA_STRINGIFY(DEFAULT_MTU)"> ) "		\
		"( net.ttl=<desired TTL, default:"SPA_STRINGIFY(DEFAULT_TTL)"> ) "		\
		"( net.loop=<desired loopback, default:"SPA_STRINGIFY(DEFAULT_LOOP)"> ) "	\
		"( sess.name=<a name for the session> ) "					\
		"( sess.min-ptime=<minimum packet time in milliseconds, default:2> ) "		\
		"( sess.max-ptime=<maximum packet time in milliseconds, default:20> ) "		\
		"( sess.media=<string, the media type audio|midi|opus, default midi> ) "	\
		"( audio.format=<format, default:"DEFAULT_FORMAT"> ) "				\
		"( audio.rate=<sample rate, default:"SPA_STRINGIFY(DEFAULT_RATE)"> ) "		\
		"( audio.channels=<number of channels, default:"SPA_STRINGIFY(DEFAULT_CHANNELS)"> ) "\
		"( audio.position=<channel map, default:"DEFAULT_POSITION"> ) "			\
		"( stream.props= { key=value ... } ) "

static const struct spa_dict_item module_info[] = {
	{ PW_KEY_MODULE_AUTHOR, "Wim Taymans <wim.taymans@gmail.com>" },
	{ PW_KEY_MODULE_DESCRIPTION, "RTP Sink" },
	{ PW_KEY_MODULE_USAGE, USAGE },
	{ PW_KEY_MODULE_VERSION, PACKAGE_VERSION },
};

struct service_info {
	AvahiIfIndex interface;
	AvahiProtocol protocol;
	const char *name;
	const char *type;
	const char *domain;
	const char *host_name;
	AvahiAddress address;
	uint16_t port;
};

#define SERVICE_INFO(...) ((struct service_info){ __VA_ARGS__ })

struct service {
	struct service_info info;

	struct spa_list link;
	struct impl *impl;

	struct session *sess;
};

struct session {
	struct impl *impl;
	struct spa_list link;

	struct sockaddr_storage ctrl_addr;
	socklen_t ctrl_len;
	struct sockaddr_storage data_addr;
	socklen_t data_len;

	struct rtp_stream *send;
	struct spa_hook send_listener;
	struct rtp_stream *recv;
	struct spa_hook recv_listener;

	char *name;

	unsigned we_initiated:1;

#define SESSION_STATE_INIT		0
#define SESSION_STATE_SENDING_CTRL_IN	1
#define SESSION_STATE_SENDING_DATA_IN	2
#define SESSION_STATE_ESTABLISHING	3
#define SESSION_STATE_ESTABLISHED	4
	int state;
	int ck_count;
	struct pw_timer timer;

	uint32_t ctrl_initiator;
	uint32_t data_initiator;
	uint32_t remote_ssrc;

	uint32_t ssrc;

	unsigned sending:1;
	unsigned receiving:1;

	unsigned ctrl_ready:1;
	unsigned data_ready:1;
};

struct impl {
	struct pw_context *context;

	struct pw_impl_module *module;
	struct spa_hook module_listener;
	struct pw_properties *props;

	bool discover_local;
	AvahiPoll *avahi_poll;
	AvahiClient *client;
	AvahiServiceBrowser *browser;
	AvahiEntryGroup *group;
	struct spa_list service_list;

	struct pw_properties *stream_props;

	struct pw_loop *loop;
	struct pw_loop *data_loop;
	struct pw_timer_queue *timer_queue;

	struct pw_core *core;
	struct spa_hook core_listener;
	struct spa_hook core_proxy_listener;
	unsigned int do_disconnect:1;

	struct spa_source *ctrl_source;
	struct spa_source *data_source;

	char *ifname;
	char *session_name;
	uint32_t ttl;
	bool mcast_loop;
	int32_t ts_offset;
	char *ts_refclk;
	int payload;

	uint16_t ctrl_port;
	struct sockaddr_storage ctrl_addr;
	socklen_t ctrl_len;
	struct sockaddr_storage data_addr;
	socklen_t data_len;

	struct spa_list sessions;
	uint32_t n_sessions;
};

static ssize_t send_packet(int fd, struct msghdr *msg)
{
	ssize_t n;
	n = sendmsg(fd, msg, MSG_NOSIGNAL);
	if (n < 0)
		pw_log_warn("sendmsg() failed: %m");
	return n;
}

static uint64_t current_time_ns(struct timespec *ts)
{
	clock_gettime(CLOCK_MONOTONIC, ts);
	return SPA_TIMESPEC_TO_NSEC(ts);
}

static void send_apple_midi_cmd_ck0(struct session *sess);

static void on_timer_event(void *data)
{
	struct session *sess = data;
	pw_log_debug("timeout");
	send_apple_midi_cmd_ck0(sess);
}

static void send_apple_midi_cmd_ck0(struct session *sess)
{
	struct impl *impl = sess->impl;
	struct iovec iov[3];
	struct msghdr msg;
	struct rtp_apple_midi_ck hdr;
	struct timespec now;
	uint64_t timeout, ts;

	spa_zero(hdr);
	hdr.cmd = htonl(APPLE_MIDI_CMD_CK);
	hdr.ssrc = htonl(sess->ssrc);

	ts = current_time_ns(&now) / 10000;
	hdr.ts1_h = htonl(ts >> 32);
	hdr.ts1_l = htonl(ts);

	iov[0].iov_base = &hdr;
	iov[0].iov_len = sizeof(hdr);

	spa_zero(msg);
	msg.msg_name = &sess->data_addr;
	msg.msg_namelen = sess->data_len;
	msg.msg_iov = iov;
	msg.msg_iovlen = 1;

	send_packet(impl->data_source->fd, &msg);

	if (sess->ck_count++ < 8)
		timeout = 1;
	else if (sess->ck_count++ < 16)
		timeout = 2;
	else
		timeout = 5;

	pw_timer_queue_add(impl->timer_queue, &sess->timer,
			&now, timeout * SPA_NSEC_PER_SEC,
			on_timer_event, sess);
}

static void session_update_state(struct session *sess, int state)
{
	if (sess->state == state)
		return;

	pw_log_info("session ssrc:%08x state:%d", sess->ssrc, state);

	sess->state = state;
	switch (state) {
	case SESSION_STATE_ESTABLISHED:
		if (sess->we_initiated) {
			sess->ck_count = 0;
			send_apple_midi_cmd_ck0(sess);
		}
		break;
	case SESSION_STATE_INIT:
		pw_timer_queue_cancel(&sess->timer);
		break;
	default:
		break;
	}
}

static void send_apple_midi_cmd_in(struct session *sess, bool ctrl)
{
	struct impl *impl = sess->impl;
	struct iovec iov[3];
	struct msghdr msg;
	struct rtp_apple_midi hdr;
	int fd;

	spa_zero(hdr);
	hdr.cmd = htonl(APPLE_MIDI_CMD_IN);
	hdr.protocol = htonl(2);
	hdr.initiator = htonl(ctrl ? sess->ctrl_initiator : sess->data_initiator);
	hdr.ssrc = htonl(sess->ssrc);

	iov[0].iov_base = &hdr;
	iov[0].iov_len = sizeof(hdr);
	iov[1].iov_base = impl->session_name;
	iov[1].iov_len = strlen(impl->session_name)+1;

	spa_zero(msg);
	if (ctrl) {
		msg.msg_name = &sess->ctrl_addr;
		msg.msg_namelen = sess->ctrl_len;
		fd = impl->ctrl_source->fd;
		session_update_state(sess, SESSION_STATE_SENDING_CTRL_IN);
	} else {
		msg.msg_name = &sess->data_addr;
		msg.msg_namelen = sess->data_len;
		fd = impl->data_source->fd;
		session_update_state(sess, SESSION_STATE_SENDING_DATA_IN);
	}
	msg.msg_iov = iov;
	msg.msg_iovlen = 2;

	send_packet(fd, &msg);
}

static void send_apple_midi_cmd_by(struct session *sess, bool ctrl)
{
	struct impl *impl = sess->impl;
	struct iovec iov[3];
	struct msghdr msg;
	struct rtp_apple_midi hdr;

	spa_zero(hdr);
	hdr.cmd = htonl(APPLE_MIDI_CMD_BY);
	hdr.protocol = htonl(2);
	hdr.initiator = htonl(ctrl ? sess->ctrl_initiator : sess->data_initiator);
	hdr.ssrc = htonl(sess->ssrc);

	iov[0].iov_base = &hdr;
	iov[0].iov_len = sizeof(hdr);

	spa_zero(msg);
	msg.msg_name = ctrl ? &sess->ctrl_addr : &sess->data_addr;
	msg.msg_namelen = ctrl ? sess->ctrl_len : sess->data_len;
	msg.msg_iov = iov;
	msg.msg_iovlen = 1;

	send_packet(ctrl ? impl->ctrl_source->fd : impl->data_source->fd, &msg);
}

static void session_establish(struct session *sess)
{
	switch (sess->state) {
	case SESSION_STATE_INIT:
		/* we initiate */
		sess->we_initiated = true;
		sess->ctrl_initiator = pw_rand32();
		sess->data_initiator = pw_rand32();

		pw_log_info("start session SSRC:%08x %u %u", sess->ssrc,
				sess->ctrl_ready, sess->data_ready);

		if (!sess->ctrl_ready)
			send_apple_midi_cmd_in(sess, true);
		else if (!sess->data_ready)
			send_apple_midi_cmd_in(sess, false);
		break;
	case SESSION_STATE_ESTABLISHING:
	case SESSION_STATE_ESTABLISHED:
		/* we're done or waiting for other initiator */
		break;
	case SESSION_STATE_SENDING_CTRL_IN:
	case SESSION_STATE_SENDING_DATA_IN:
		/* we're busy initiating */
		break;
	}
}

static void session_stop(struct session *sess)
{
	if (!sess->we_initiated)
		return;
	pw_log_info("stop session SSRC:%08x %u %u", sess->ssrc,
			sess->ctrl_ready, sess->data_ready);
	if (sess->ctrl_ready) {
		send_apple_midi_cmd_by(sess, true);
		sess->ctrl_ready = false;
	}
	if (sess->data_ready) {
		send_apple_midi_cmd_by(sess, false);
		sess->data_ready = false;
	}
	session_update_state(sess, SESSION_STATE_INIT);
}

static void send_destroy(void *data)
{
}

static void send_open_connection(void *data, int *result)
{
	struct session *sess = data;
	sess->sending = true;
	if (result)
		*result = 1;
	session_establish(sess);
}

static void send_close_connection(void *data, int *result)
{
	struct session *sess = data;
	sess->sending = false;
	if (result)
		*result = 1;
	if (!sess->receiving)
		session_stop(sess);
}

static void send_send_packet(void *data, struct iovec *iov, size_t iovlen)
{
	struct session *sess = data;
	struct impl *impl = sess->impl;
	struct msghdr msg;

	if (!sess->data_ready || !sess->sending)
		return;

	spa_zero(msg);
	msg.msg_name = &sess->data_addr;
	msg.msg_namelen = sess->data_len;
	msg.msg_iov = iov;
	msg.msg_iovlen = iovlen;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	msg.msg_flags = 0;

	send_packet(impl->data_source->fd, &msg);
}

static void recv_destroy(void *data)
{
}

static void recv_open_connection(void *data, int *result)
{
	struct session *sess = data;
	sess->receiving = true;
	if (result)
		*result = 1;
	session_establish(sess);
}

static void recv_close_connection(void *data, int *result)
{
	struct session *sess = data;
	sess->receiving = false;
	if (result)
		*result = 1;
	if (!sess->sending)
		session_stop(sess);
}

static void recv_send_feedback(void *data, uint32_t seqnum)
{
	struct session *sess = data;
	struct impl *impl = sess->impl;
	struct iovec iov[1];
	struct msghdr msg;
	struct rtp_apple_midi_rs hdr;

	if (!sess->ctrl_ready || !sess->receiving)
		return;

	spa_zero(hdr);
	hdr.cmd = htonl(APPLE_MIDI_CMD_RS);
	hdr.ssrc = htonl(sess->ssrc);
	hdr.seqnum = htonl(seqnum);

	iov[0].iov_base = &hdr;
	iov[0].iov_len = sizeof(hdr);

	spa_zero(msg);
	msg.msg_name = &sess->ctrl_addr;
	msg.msg_namelen = sess->ctrl_len;
	msg.msg_iov = iov;
	msg.msg_iovlen = 1;

	send_packet(impl->ctrl_source->fd, &msg);
}

static const struct rtp_stream_events send_stream_events = {
	RTP_VERSION_STREAM_EVENTS,
	.destroy = send_destroy,
	.open_connection = send_open_connection,
	.close_connection = send_close_connection,
	.send_packet = send_send_packet,
};

static const struct rtp_stream_events recv_stream_events = {
	RTP_VERSION_STREAM_EVENTS,
	.destroy = recv_destroy,
	.open_connection = recv_open_connection,
	.close_connection = recv_close_connection,
	.send_feedback = recv_send_feedback,
};

static int
do_unlink_session(struct spa_loop *loop,
		bool async, uint32_t seq, const void *data, size_t size, void *user_data)
{
	struct session *sess = user_data;
	spa_list_remove(&sess->link);
	return 0;
}

static void free_session(struct session *sess)
{
	struct impl *impl = sess->impl;

	pw_loop_locked(impl->data_loop, do_unlink_session, 1, NULL, 0, sess);

	sess->impl->n_sessions--;
	pw_timer_queue_cancel(&sess->timer);

	if (sess->send)
		rtp_stream_destroy(sess->send);
	if (sess->recv)
		rtp_stream_destroy(sess->recv);
	free(sess->name);
	free(sess);
}

static bool cmp_ip(const struct sockaddr_storage *sa, const struct sockaddr_storage *sb)
{
	if (sa->ss_family == AF_INET && sb->ss_family == AF_INET) {
		struct sockaddr_in *ia = (struct sockaddr_in*)sa;
		struct sockaddr_in *ib = (struct sockaddr_in*)sb;
		return ia->sin_addr.s_addr == ib->sin_addr.s_addr;
	} else if (sa->ss_family == AF_INET6 && sb->ss_family == AF_INET6) {
		struct sockaddr_in6 *ia = (struct sockaddr_in6*)sa;
		struct sockaddr_in6 *ib = (struct sockaddr_in6*)sb;
		return ia->sin6_addr.s6_addr == ib->sin6_addr.s6_addr && ia->sin6_scope_id == ib->sin6_scope_id;
	}
	return false;
}

static struct session *make_session(struct impl *impl, struct pw_properties *props)
{
	struct session *sess;
	const char *str;
	struct pw_properties *copy;

	sess = calloc(1, sizeof(struct session));
	if (sess == NULL)
		goto error;

	spa_list_append(&impl->sessions, &sess->link);
	impl->n_sessions++;

	sess->impl = impl;
	sess->ssrc = pw_rand32();

	str = pw_properties_get(props, "sess.name");
	sess->name = str ? strdup(str) : strdup("RTP Session");

	if (impl->ts_refclk != NULL)
		pw_properties_setf(props, "rtp.sender-ts-offset", "%u", impl->ts_offset);
	pw_properties_setf(props, "rtp.sender-ssrc", "%u", sess->ssrc);
	pw_properties_set(props, "rtp.session", sess->name);

	if (pw_properties_get(props, PW_KEY_NODE_GROUP) == NULL)
		pw_properties_set(props, PW_KEY_NODE_GROUP, impl->session_name);

	copy = pw_properties_copy(props);

	if (pw_properties_get(props, PW_KEY_MEDIA_CLASS) == NULL) {
		const char *media = NULL;

		str = pw_properties_get(props, "sess.media");
		if (spa_streq(str, "midi"))
			media = "Midi";
		else if (spa_streq(str, "audio") || spa_streq(str, "opus"))
			media = "Audio";

		if (media != NULL) {
			pw_properties_setf(copy, PW_KEY_MEDIA_CLASS, "%s/Sink", media);
			pw_properties_setf(props, PW_KEY_MEDIA_CLASS, "%s/Source", media);
		}
	}

	sess->send = rtp_stream_new(impl->core,
			PW_DIRECTION_INPUT, copy,
			&send_stream_events, sess);
	sess->recv = rtp_stream_new(impl->core,
			PW_DIRECTION_OUTPUT, props,
			&recv_stream_events, sess);

	return sess;
error:
	pw_properties_free(props);
	return NULL;
}

static struct session *find_session_by_addr_name(struct impl *impl,
		const struct sockaddr_storage *sa, const char *name)
{
	struct session *sess;
	spa_list_for_each(sess, &impl->sessions, link) {
		pw_log_info("%p '%s' '%s'", sess, name, sess->name);
		if (cmp_ip(sa, &sess->ctrl_addr) &&
		    spa_streq(sess->name, name))
			return sess;
	}
	return NULL;
}
static struct session *find_session_by_initiator(struct impl *impl, uint32_t initiator, bool ctrl)
{
	struct session *sess;
	spa_list_for_each(sess, &impl->sessions, link) {
		uint32_t target = ctrl ? sess->ctrl_initiator : sess->data_initiator;
		if (target == initiator)
			return sess;
	}
	return NULL;
}

static struct session *find_session_by_ssrc(struct impl *impl, uint32_t ssrc)
{
	struct session *sess;
	spa_list_for_each(sess, &impl->sessions, link) {
		if (sess->remote_ssrc == ssrc)
			return sess;
	}
	return NULL;
}

static void parse_apple_midi_cmd_in(struct impl *impl, bool ctrl, uint8_t *buffer,
		ssize_t len, struct sockaddr_storage *sa, socklen_t salen)
{
	struct rtp_apple_midi *hdr = (struct rtp_apple_midi*)buffer;
	struct iovec iov[3];
	struct msghdr msg;
	struct rtp_apple_midi reply;
	struct session *sess;
	bool success = true;
	uint32_t initiator, ssrc;
	char addr[128];
	uint16_t port = 0;

	initiator = ntohl(hdr->initiator);
	ssrc = ntohl(hdr->ssrc);

	pw_net_get_ip(sa, addr, sizeof(addr), NULL, &port);
	pw_log_info("IN from %s:%d %s ssrc:%08x initiator:%08x",
			addr, port, hdr->name, ssrc, initiator);

	if (ctrl) {
		sess = find_session_by_addr_name(impl, sa, hdr->name);
		if (sess == NULL) {
			pw_log_warn("receive ctrl IN from nonexisting session %s", hdr->name);
			success = false;
		} else {
			if (sess->ctrl_ready &&
			    (sess->remote_ssrc != ssrc || sess->ctrl_initiator != initiator)) {
				pw_log_warn("receive ctrl IN from existing initiator:%08x", initiator);
			}
		}
		if (success) {
			sess->we_initiated = false;
			sess->remote_ssrc = ssrc;
			sess->ctrl_initiator = initiator;
			sess->ctrl_addr = *sa;
			sess->ctrl_len = salen;
			sess->ctrl_ready = true;
			session_update_state(sess, SESSION_STATE_ESTABLISHING);
		}
	}
	else {
		sess = find_session_by_ssrc(impl, ssrc);
		if (sess == NULL) {
			pw_log_warn("receive data IN from nonexisting ssrc:%08x", ssrc);
			success = false;
		} else {
			if (sess->data_ready) {
				pw_log_warn("receive data IN from existing initiator:%08x", initiator);
			}
		}
		if (success) {
			pw_log_info("got data IN initiator:%08x, session established", initiator);
			sess->data_initiator = initiator;
			sess->data_addr = *sa;
			sess->data_len = salen;
			sess->data_ready = true;
			session_update_state(sess, SESSION_STATE_ESTABLISHED);
		}
	}

	reply = *hdr;
	if (success) {
		reply.cmd = htonl(APPLE_MIDI_CMD_OK);
		reply.ssrc = htonl(sess->ssrc);
	} else
		reply.cmd = htonl(APPLE_MIDI_CMD_NO);

	iov[0].iov_base = &reply;
	iov[0].iov_len = sizeof(reply);
	iov[1].iov_base = impl->session_name;
	iov[1].iov_len = strlen(impl->session_name)+1;

	spa_zero(msg);
	msg.msg_name = sa;
	msg.msg_namelen = salen;
	msg.msg_iov = iov;
	msg.msg_iovlen = 2;

	pw_log_trace("send %p %u", msg.msg_name, msg.msg_namelen);

	send_packet(ctrl ? impl->ctrl_source->fd : impl->data_source->fd, &msg);
}

static void parse_apple_midi_cmd_ok(struct impl *impl, bool ctrl, uint8_t *buffer,
		ssize_t len, struct sockaddr_storage *sa, socklen_t salen)
{
	struct rtp_apple_midi *hdr = (struct rtp_apple_midi*)buffer;
	uint32_t initiator = ntohl(hdr->initiator);
	struct session *sess;

	sess = find_session_by_initiator(impl, initiator, ctrl);
	if (sess == NULL || !sess->we_initiated) {
		pw_log_warn("received OK from nonexisting session %u", initiator);
		return;
	}

	if (ctrl) {
		pw_log_info("got ctrl OK %08x %u", initiator, sess->data_ready);
		sess->ctrl_ready = true;
		if (!sess->data_ready)
			send_apple_midi_cmd_in(sess, false);
	} else {
		pw_log_info("got data OK %08x %u, session established", initiator,
				sess->ctrl_ready);
		sess->remote_ssrc = ntohl(hdr->ssrc);
		sess->data_ready = true;
		if (sess->ctrl_ready)
			session_update_state(sess, SESSION_STATE_ESTABLISHED);
	}
}

static void parse_apple_midi_cmd_no(struct impl *impl, bool ctrl, uint8_t *buffer,
		ssize_t len, struct sockaddr_storage *sa, socklen_t salen)
{
	struct rtp_apple_midi *hdr = (struct rtp_apple_midi*)buffer;
	uint32_t initiator = ntohl(hdr->initiator);
	struct session *sess;

	sess = find_session_by_initiator(impl, initiator, ctrl);
	if (sess == NULL || !sess->we_initiated) {
		pw_log_warn("received NO from nonexisting session %u", initiator);
		return;
	}

	if (ctrl) {
		pw_log_info("got ctrl NO %08x %u", initiator, sess->data_ready);
		sess->ctrl_ready = false;
	} else {
		pw_log_info("got data NO %08x %u, session canceled", initiator,
				sess->ctrl_ready);
		sess->data_ready = false;
		if (!sess->ctrl_ready)
			session_update_state(sess, SESSION_STATE_INIT);
	}
}

static void parse_apple_midi_cmd_ck(struct impl *impl, bool ctrl, uint8_t *buffer,
		ssize_t len, struct sockaddr_storage *sa, socklen_t salen)
{
	struct rtp_apple_midi_ck *hdr = (struct rtp_apple_midi_ck*)buffer;
	struct iovec iov[3];
	struct msghdr msg;
	struct rtp_apple_midi_ck reply;
	struct session *sess;
	uint64_t ts, t1, t2, t3;
	uint32_t ssrc = ntohl(hdr->ssrc);
	struct timespec now;

	sess = find_session_by_ssrc(impl, ssrc);
	if (sess == NULL) {
		pw_log_warn("unknown SSRC %u", ssrc);
		return;
	}

	pw_log_trace("got CK count %d", hdr->count);

	ts = current_time_ns(&now) / 10000;
	reply = *hdr;
	reply.ssrc = htonl(sess->ssrc);
	reply.count++;
	iov[0].iov_base = &reply;
	iov[0].iov_len = sizeof(reply);

	t1 = ((uint64_t)ntohl(hdr->ts1_h) << 32) | ntohl(hdr->ts1_l);
	t2 = t3 = 0;

	switch (hdr->count) {
	case 0:
		t2 = ts;
		break;
	case 1:
		t2 = ((uint64_t)ntohl(hdr->ts2_h) << 32) | ntohl(hdr->ts2_l);
		t3 = ts;
		break;
	case 2:
		t3 = ((uint64_t)ntohl(hdr->ts3_h) << 32) | ntohl(hdr->ts3_l);
		return;
	}

	if (hdr->count >= 1) {
		int64_t latency, offset;
		latency = t3 - t1;
		offset = ((t3 + t1) / 2) - t2;

		pw_log_trace("latency:%f offset:%f", latency / 1e5, offset / 1e5);
		if (hdr->count >= 2)
			return;
	}

	reply.ts2_h = htonl(t2 >> 32);
	reply.ts2_l = htonl(t2);
	reply.ts3_h = htonl(t3 >> 32);
	reply.ts3_l = htonl(t3);

	spa_zero(msg);
	msg.msg_name = sa;
	msg.msg_namelen = salen;
	msg.msg_iov = iov;
	msg.msg_iovlen = 1;

	pw_log_trace("send %p %u", msg.msg_name, msg.msg_namelen);

	send_packet(ctrl ? impl->ctrl_source->fd : impl->data_source->fd, &msg);
}

static void parse_apple_midi_cmd_by(struct impl *impl, bool ctrl, uint8_t *buffer,
		ssize_t len, struct sockaddr_storage *sa, socklen_t salen)
{
	struct rtp_apple_midi *hdr = (struct rtp_apple_midi*)buffer;
	uint32_t initiator = ntohl(hdr->initiator);
	struct session *sess;

	sess = find_session_by_initiator(impl, initiator, ctrl);
	if (sess == NULL || sess->we_initiated) {
		pw_log_warn("received BY from nonexisting initiator %08x", initiator);
		return;
	}

	if (ctrl) {
		pw_log_info("%p: got ctrl BY %08x %u", sess, initiator, sess->data_ready);
		sess->ctrl_ready = false;
		if (!sess->data_ready)
			session_update_state(sess, SESSION_STATE_INIT);
	} else {
		pw_log_info("%p: got data BY %08x %u", sess, initiator, sess->ctrl_ready);
		sess->data_ready = false;
		if (!sess->ctrl_ready)
			session_update_state(sess, SESSION_STATE_INIT);
	}
}

static void parse_apple_midi_cmd_rs(struct impl *impl, bool ctrl, uint8_t *buffer,
		ssize_t len, struct sockaddr_storage *sa, socklen_t salen)
{
	struct rtp_apple_midi_rs *hdr = (struct rtp_apple_midi_rs*)buffer;
	struct session *sess;
	uint32_t ssrc, seqnum;

	ssrc = ntohl(hdr->ssrc);
	sess = find_session_by_ssrc(impl, ssrc);
	if (sess == NULL) {
		pw_log_warn("unknown SSRC %u", ssrc);
		return;
	}

	seqnum = ntohl(hdr->seqnum);
	pw_log_debug("got RS seqnum %u", seqnum);
}

static void parse_apple_midi_cmd(struct impl *impl, bool ctrl, uint8_t *buffer,
		ssize_t len, struct sockaddr_storage *sa, socklen_t salen)
{
	struct rtp_apple_midi *hdr = (struct rtp_apple_midi*)buffer;
	switch (ntohl(hdr->cmd)) {
	case APPLE_MIDI_CMD_IN:
		parse_apple_midi_cmd_in(impl, ctrl, buffer, len, sa, salen);
		break;
	case APPLE_MIDI_CMD_OK:
		parse_apple_midi_cmd_ok(impl, ctrl, buffer, len, sa, salen);
		break;
	case APPLE_MIDI_CMD_NO:
		parse_apple_midi_cmd_no(impl, ctrl, buffer, len, sa, salen);
		break;
	case APPLE_MIDI_CMD_CK:
		parse_apple_midi_cmd_ck(impl, ctrl, buffer, len, sa, salen);
		break;
	case APPLE_MIDI_CMD_BY:
		parse_apple_midi_cmd_by(impl, ctrl, buffer, len, sa, salen);
		break;
	case APPLE_MIDI_CMD_RS:
		parse_apple_midi_cmd_rs(impl, ctrl, buffer, len, sa, salen);
		break;
	default:
		break;
	}
}

static void
on_ctrl_io(void *data, int fd, uint32_t mask)
{
	struct impl *impl = data;
	ssize_t len;
	uint8_t buffer[2048];

	if (mask & SPA_IO_IN) {
		struct sockaddr_storage sa;
		socklen_t salen = sizeof(sa);

		if ((len = recvfrom(fd, buffer, sizeof(buffer), 0,
					(struct sockaddr*)&sa, &salen)) < 0)
			goto receive_error;

		if (len < 12)
			goto short_packet;

		if (buffer[0] == 0xff && buffer[1] == 0xff) {
			parse_apple_midi_cmd(impl, true, buffer, len, &sa, salen);
		} else {
			spa_debug_log_mem(pw_log_get(), SPA_LOG_LEVEL_DEBUG, 0, buffer, len);
		}
	}
	return;

receive_error:
	pw_log_warn("recv error: %m");
	return;
short_packet:
	pw_log_warn("short packet received");
	spa_debug_log_mem(pw_log_get(), SPA_LOG_LEVEL_DEBUG, 0, buffer, len);
	return;
}

static void
on_data_io(void *data, int fd, uint32_t mask)
{
	struct impl *impl = data;
	ssize_t len;
	uint8_t buffer[2048];
	uint32_t ssrc;

	if (mask & SPA_IO_IN) {
		struct sockaddr_storage sa;
		socklen_t salen = sizeof(sa);

		if ((len = recvfrom(fd, buffer, sizeof(buffer), 0,
					(struct sockaddr*)&sa, &salen)) < 0)
			goto receive_error;

		if (len < 12)
			goto short_packet;

		if (buffer[0] == 0xff && buffer[1] == 0xff) {
			parse_apple_midi_cmd(impl, false, buffer, len, &sa, salen);
		} else {
			struct rtp_header *hdr = (struct rtp_header*)buffer;
			struct session *sess;

			ssrc = ntohl(hdr->ssrc);
			sess = find_session_by_ssrc(impl, ssrc);
			if (sess == NULL)
				goto unknown_ssrc;

			if (sess->data_ready && sess->receiving)
				rtp_stream_receive_packet(sess->recv, buffer, len);
		}
	}
	return;

receive_error:
	pw_log_warn("recv error: %m");
	return;
short_packet:
	pw_log_warn("short packet received");
	spa_debug_log_mem(pw_log_get(), SPA_LOG_LEVEL_DEBUG, 0, buffer, len);
	return;
unknown_ssrc:
	pw_log_debug("unknown SSRC %08x", ssrc);
	return;
}

static int make_socket(const struct sockaddr_storage* sa, socklen_t salen,
		bool loop, int ttl, char *ifname)
{
	int af, fd, val, res;
	struct ifreq req;
	struct sockaddr_storage src = *sa;
	bool is_multicast = false;

	af = sa->ss_family;
	if ((fd = socket(af, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0)) < 0) {
		pw_log_error("socket failed: %m");
		return -errno;
	}
#ifdef SO_TIMESTAMP
	val = 1;
	if (setsockopt(fd, SOL_SOCKET, SO_TIMESTAMP, &val, sizeof(val)) < 0) {
		res = -errno;
		pw_log_error("setsockopt failed: %m");
		goto error;
	}
#endif
	val = 1;
	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)) < 0) {
		res = -errno;
		pw_log_error("setsockopt failed: %m");
		goto error;
	}

	spa_zero(req);
	if (ifname) {
		snprintf(req.ifr_name, sizeof(req.ifr_name), "%s", ifname);
		res = ioctl(fd, SIOCGIFINDEX, &req);
	        if (res < 0)
	                pw_log_warn("SIOCGIFINDEX %s failed: %m", ifname);
	}
	res = 0;
	if (af == AF_INET) {
		static const uint32_t ipv4_mcast_mask = 0xe0000000;
		struct sockaddr_in *sa4 = (struct sockaddr_in*)&src;
		if ((ntohl(sa4->sin_addr.s_addr) & ipv4_mcast_mask) == ipv4_mcast_mask) {
			struct ip_mreqn mr4;
			memset(&mr4, 0, sizeof(mr4));
			mr4.imr_multiaddr = sa4->sin_addr;
			mr4.imr_ifindex = req.ifr_ifindex;
			res = setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mr4, sizeof(mr4));
			is_multicast = true;
		} else {
			sa4->sin_addr.s_addr = INADDR_ANY;
		}
	} else if (af == AF_INET6) {
		struct sockaddr_in6 *sa6 = (struct sockaddr_in6*)&src;
		if (sa6->sin6_addr.s6_addr[0] == 0xff) {
			struct ipv6_mreq mr6;
			memset(&mr6, 0, sizeof(mr6));
			mr6.ipv6mr_multiaddr = sa6->sin6_addr;
			mr6.ipv6mr_interface = req.ifr_ifindex;
			res = setsockopt(fd, IPPROTO_IPV6, IPV6_JOIN_GROUP, &mr6, sizeof(mr6));
			is_multicast = true;
		} else {
		        sa6->sin6_addr = in6addr_any;
		}
	} else {
		res = -EINVAL;
		goto error;
	}

	if (res < 0) {
		res = -errno;
		pw_log_error("join mcast failed: %m");
		goto error;
	}
	if (is_multicast) {
		val = loop;
		if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &val, sizeof(val)) < 0)
			pw_log_warn("setsockopt(IP_MULTICAST_LOOP) failed: %m");

		val = ttl;
		if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &val, sizeof(val)) < 0)
			pw_log_warn("setsockopt(IP_MULTICAST_TTL) failed: %m");
	}

	if (bind(fd, (struct sockaddr*)&src, salen) < 0) {
		res = -errno;
		pw_log_error("bind() failed: %m");
		goto error;
	}
	val = IPTOS_LOWDELAY;
	if (setsockopt(fd, IPPROTO_IP, IP_TOS, &val, sizeof(val)) < 0)
		pw_log_warn("setsockopt(IP_TOS) failed: %m");

	pw_log_debug("new socket fd:%d", fd);

	return fd;
error:
	close(fd);
	return res;
}

static int setup_apple_session(struct impl *impl)
{
	int fd;

	if ((fd = make_socket(&impl->ctrl_addr, impl->ctrl_len,
				impl->mcast_loop, impl->ttl, impl->ifname)) < 0) {
		return fd;
	}
	impl->ctrl_source = pw_loop_add_io(impl->loop, fd,
					SPA_IO_IN, true, on_ctrl_io, impl);

	if (impl->ctrl_source == NULL) {
		close(fd);
		return -errno;
	}

	if ((fd = make_socket(&impl->data_addr, impl->data_len,
				impl->mcast_loop, impl->ttl, impl->ifname)) < 0)
		return fd;

	impl->data_source = pw_loop_add_io(impl->data_loop, fd,
				SPA_IO_IN, true, on_data_io, impl);
	if (impl->data_source == NULL) {
		close(fd);
		return -errno;
	}
	return 0;
}

static void core_destroy(void *d)
{
	struct impl *impl = d;
	spa_hook_remove(&impl->core_listener);
	impl->core = NULL;
	pw_impl_module_schedule_destroy(impl->module);
}

static const struct pw_proxy_events core_proxy_events = {
	.destroy = core_destroy,
};

static void impl_destroy(struct impl *impl)
{
	struct session *sess;

	spa_list_consume(sess, &impl->sessions, link)
		free_session(sess);

	if (impl->core && impl->do_disconnect)
		pw_core_disconnect(impl->core);

	if (impl->ctrl_source)
		pw_loop_destroy_source(impl->loop, impl->ctrl_source);
	if (impl->data_source)
		pw_loop_destroy_source(impl->data_loop, impl->data_source);

	if (impl->client)
		avahi_client_free(impl->client);

	if (impl->data_loop)
		pw_context_release_loop(impl->context, impl->data_loop);

	pw_properties_free(impl->stream_props);
	pw_properties_free(impl->props);

	free(impl->ifname);
	free(impl->ts_refclk);
	free(impl->session_name);
	free(impl);
}

static void module_destroy(void *d)
{
	struct impl *impl = d;
	spa_hook_remove(&impl->module_listener);
	impl_destroy(impl);
}

static const struct pw_impl_module_events module_events = {
	PW_VERSION_IMPL_MODULE_EVENTS,
	.destroy = module_destroy,
};

static void on_core_error(void *d, uint32_t id, int seq, int res, const char *message)
{
	struct impl *impl = d;

	pw_log_error("error id:%u seq:%d res:%d (%s): %s",
			id, seq, res, spa_strerror(res), message);

	if (id == PW_ID_CORE && res == -EPIPE)
		pw_impl_module_schedule_destroy(impl->module);
}

static const struct pw_core_events core_events = {
	PW_VERSION_CORE_EVENTS,
	.error = on_core_error,
};

static void free_service(struct service *s)
{
	spa_list_remove(&s->link);

	if (s->sess)
		free_session(s->sess);

	free((char *) s->info.name);
	free((char *) s->info.type);
	free((char *) s->info.domain);
	free((char *) s->info.host_name);
	free(s);
}

static const char *get_service_name(struct impl *impl)
{
	const char *str;
	str = pw_properties_get(impl->props, "sess.media");
	if (spa_streq(str, "midi"))
		return "_apple-midi._udp";
	else if (spa_streq(str, "audio") || spa_streq(str, "opus"))
		return "_pipewire-audio._udp";
	return NULL;
}

static struct service *make_service(struct impl *impl, const struct service_info *info,
		AvahiStringList *txt)
{
	struct service *s = NULL;
	char at[AVAHI_ADDRESS_STR_MAX], if_suffix[16] = "";
	struct session *sess;
	int res, ipv;
	struct pw_properties *props = NULL;
	const char *service_name, *str;
	AvahiStringList *l;
	bool compatible = true;

	/* check for compatible session */
	service_name = get_service_name(impl);
	compatible = spa_streq(service_name, info->type);

	props = pw_properties_copy(impl->stream_props);
	if (props == NULL) {
		res = -errno;
		goto error;
	}

	if (spa_streq(service_name, "_pipewire-audio._udp")) {
		uint32_t mask = 0;
		for (l = txt; l && compatible; l = l->next) {
			const char *k = NULL;
			char *key, *value;

			if (avahi_string_list_get_pair(l, &key, &value, NULL) != 0)
				break;

			if (spa_streq(key, "subtype")) {
				k = "sess.media";
				mask |= 1<<0;
			} else if (spa_streq(key, "format")) {
				k = PW_KEY_AUDIO_FORMAT;
				mask |= 1<<1;
			} else if (spa_streq(key, "rate")) {
				k = PW_KEY_AUDIO_RATE;
				mask |= 1<<2;
			} else if (spa_streq(key, "channels")) {
				k = PW_KEY_AUDIO_CHANNELS;
				mask |= 1<<3;
			} else if (spa_streq(key, "channelnames")) {
				pw_properties_set(props,
						PW_KEY_NODE_CHANNELNAMES, value);
			} else if (spa_streq(key, "ts-refclk")) {
				pw_properties_set(props,
					"sess.ts-refclk", value);
				if (spa_streq(value, impl->ts_refclk))
					pw_properties_set(props,
						"sess.ts-direct", "true");
			} else if (spa_streq(key, "ts-offset")) {
				uint32_t v;
				if (spa_atou32(value, &v, 0))
					pw_properties_setf(props,
						"rtp.receiver-ts-offset", "%u", v);
			}
			if (k != NULL) {
				str = pw_properties_get(props, k);
				if (str == NULL || !spa_streq(str, value))
					compatible = false;
			}
			avahi_free(key);
			avahi_free(value);
		}
		str = pw_properties_get(props, "sess.media");
		if (spa_streq(str, "opus") && mask != 0xd)
			compatible = false;
		if (spa_streq(str, "audio") && mask != 0xf)
			compatible = false;
	}
	if (!compatible) {
		pw_log_info("found incompatible session IP%d:%s",
				info->protocol == AVAHI_PROTO_INET ? 4 : 6,
				info->name);
		res = 0;
		goto error;
	}

	s = calloc(1, sizeof(*s));
	if (s == NULL) {
		res = -errno;
		goto error;
	}

	s->impl = impl;
	spa_list_append(&impl->service_list, &s->link);

	s->info.interface = info->interface;
	s->info.protocol = info->protocol;
	s->info.name = strdup(info->name);
	s->info.type = strdup(info->type);
	s->info.domain = strdup(info->domain);
	s->info.host_name = strdup(info->host_name);
	s->info.address = info->address;
	s->info.port = info->port;

	avahi_address_snprint(at, sizeof(at), &s->info.address);
	pw_log_info("create session: %s %s:%u %s", s->info.name, at, s->info.port, s->info.type);

	if (s->info.protocol == AVAHI_PROTO_INET6 &&
	    s->info.address.data.ipv6.address[0] == 0xfe &&
	    (s->info.address.data.ipv6.address[1] & 0xc0) == 0x80)
		snprintf(if_suffix, sizeof(if_suffix), "%%%d", s->info.interface);

	ipv = s->info.protocol == AVAHI_PROTO_INET ? 4 : 6;
	pw_properties_set(props, "sess.name", s->info.name);
	pw_properties_setf(props, "destination.ip", "%s%s", at, if_suffix);
	pw_properties_setf(props, "destination.ifindex", "%u", s->info.interface);
	pw_properties_setf(props, "destination.port", "%u", s->info.port);

	if (pw_properties_get(props, PW_KEY_NODE_NAME) == NULL)
		pw_properties_setf(props, PW_KEY_NODE_NAME, "rtp_session.%s.%s.ipv%d",
				s->info.name, s->info.host_name, ipv);
	if (pw_properties_get(props, PW_KEY_NODE_DESCRIPTION) == NULL)
		pw_properties_setf(props, PW_KEY_NODE_DESCRIPTION, "%s (IPv%d)",
				s->info.name, ipv);
	if (pw_properties_get(props, PW_KEY_MEDIA_NAME) == NULL)
		pw_properties_setf(props, PW_KEY_MEDIA_NAME, "RTP Session with %s (IPv%d)",
				s->info.name, ipv);

	sess = make_session(impl, props);
	props = NULL;
	if (sess == NULL) {
		res = -errno;
		pw_log_error("can't create session: %m");
		goto error;
	}
	s->sess = sess;

	if ((res = pw_net_parse_address(at, s->info.port, &sess->ctrl_addr, &sess->ctrl_len)) < 0) {
		pw_log_error("invalid address %s: %s", at, spa_strerror(res));
	}
	if ((res = pw_net_parse_address(at, s->info.port+1, &sess->data_addr, &sess->data_len)) < 0) {
		pw_log_error("invalid address %s: %s", at, spa_strerror(res));
	}
	return s;
error:
	pw_properties_free(props);
	if (s != NULL)
		free_service(s);
	errno = -res;
	return NULL;
}

static struct service *find_service(struct impl *impl, const struct service_info *info)
{
	struct service *s;
	spa_list_for_each(s, &impl->service_list, link) {
		if (s->info.interface == info->interface &&
		    s->info.protocol == info->protocol &&
		    spa_streq(s->info.name, info->name) &&
		    spa_streq(s->info.type, info->type) &&
		    spa_streq(s->info.domain, info->domain))
			return s;
	}
	return NULL;
}

static void resolver_cb(AvahiServiceResolver *r, AvahiIfIndex interface, AvahiProtocol protocol,
	AvahiResolverEvent event, const char *name, const char *type, const char *domain,
	const char *host_name, const AvahiAddress *a, uint16_t port, AvahiStringList *txt,
	AvahiLookupResultFlags flags, void *userdata)
{
	struct impl *impl = userdata;
	struct service_info sinfo;

	if (event != AVAHI_RESOLVER_FOUND) {
		pw_log_error("Resolving of '%s' failed: %s", name,
				avahi_strerror(avahi_client_errno(impl->client)));
		goto done;
	}

	sinfo = SERVICE_INFO(.interface = interface,
			.protocol = protocol,
			.name = name,
			.type = type,
			.domain = domain,
			.host_name = host_name,
			.address = *a,
			.port = port);

	make_service(impl, &sinfo, txt);
done:
	avahi_service_resolver_free(r);
}

static void browser_cb(AvahiServiceBrowser *b, AvahiIfIndex interface, AvahiProtocol protocol,
	AvahiBrowserEvent event, const char *name, const char *type, const char *domain,
	AvahiLookupResultFlags flags, void *userdata)
{
	struct impl *impl = userdata;
	struct service_info info;
	struct service *s;

	if ((flags & AVAHI_LOOKUP_RESULT_LOCAL) && !impl->discover_local)
		return;

	info = SERVICE_INFO(.interface = interface,
			.protocol = protocol,
			.name = name,
			.type = type,
			.domain = domain);

	s = find_service(impl, &info);

	switch (event) {
	case AVAHI_BROWSER_NEW:
		if (s != NULL)
			return;
		if (!(avahi_service_resolver_new(impl->client,
						interface, protocol,
						name, type, domain,
						AVAHI_PROTO_UNSPEC, 0,
						resolver_cb, impl)))
			pw_log_error("can't make service resolver: %s",
					avahi_strerror(avahi_client_errno(impl->client)));
		break;
	case AVAHI_BROWSER_REMOVE:
		if (s == NULL)
			return;
		free_service(s);
		break;
	default:
		break;
	}
}

static int make_browser(struct impl *impl)
{
	const char *service_name;

	service_name = get_service_name(impl);
	if (service_name == NULL)
		return -EINVAL;

	if (impl->browser == NULL) {
		impl->browser = avahi_service_browser_new(impl->client,
				AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC,
				service_name, NULL, 0,
				browser_cb, impl);
	}
	if (impl->browser == NULL) {
		pw_log_error("can't make browser: %s",
			avahi_strerror(avahi_client_errno(impl->client)));
		return -EIO;
	}
	return 0;
}

static void entry_group_callback(AvahiEntryGroup *g, AvahiEntryGroupState state, void *userdata)
{
	switch (state) {
	case AVAHI_ENTRY_GROUP_ESTABLISHED:
		pw_log_info("Service successfully established");
		break;
	case AVAHI_ENTRY_GROUP_COLLISION:
		pw_log_error("Service name collision");
		break;
	case AVAHI_ENTRY_GROUP_FAILURE:
		pw_log_error("Entry group failure: %s",
			avahi_strerror(avahi_client_errno(avahi_entry_group_get_client(g))));
		break;
	case AVAHI_ENTRY_GROUP_UNCOMMITED:
	case AVAHI_ENTRY_GROUP_REGISTERING:;
		break;
	}
}

static int make_announce(struct impl *impl)
{
	int res;
	const char *service_name, *str;
	AvahiStringList *txt = NULL;

	if ((service_name = get_service_name(impl)) == NULL)
		return -ENOTSUP;

	if (impl->group == NULL) {
		impl->group = avahi_entry_group_new(impl->client,
					entry_group_callback, impl);
	}
	if (impl->group == NULL) {
		pw_log_error("can't make group: %s",
			avahi_strerror(avahi_client_errno(impl->client)));
		return -EIO;
	}
	avahi_entry_group_reset(impl->group);

	if (spa_streq(service_name, "_pipewire-audio._udp")) {
		str = pw_properties_get(impl->props, "sess.media");
		txt = avahi_string_list_add_pair(txt, "subtype", str);
		if ((str = pw_properties_get(impl->stream_props, PW_KEY_AUDIO_FORMAT)) != NULL)
			txt = avahi_string_list_add_pair(txt, "format", str);
		if ((str = pw_properties_get(impl->stream_props, PW_KEY_AUDIO_RATE)) != NULL)
			txt = avahi_string_list_add_pair(txt, "rate", str);
		if ((str = pw_properties_get(impl->stream_props, PW_KEY_AUDIO_CHANNELS)) != NULL)
			txt = avahi_string_list_add_pair(txt, "channels", str);
		if ((str = pw_properties_get(impl->stream_props, SPA_KEY_AUDIO_POSITION)) != NULL)
			txt = avahi_string_list_add_pair(txt, "position", str);
		if ((str = pw_properties_get(impl->stream_props, PW_KEY_NODE_CHANNELNAMES)) != NULL)
			txt = avahi_string_list_add_pair(txt, "channelnames", str);
		if (impl->ts_refclk != NULL) {
			txt = avahi_string_list_add_pair(txt, "ts-refclk", impl->ts_refclk);
			txt = avahi_string_list_add_printf(txt, "ts-offset=%u", impl->ts_offset);
		}
	}
	res = avahi_entry_group_add_service_strlst(impl->group,
			AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC,
			(AvahiPublishFlags)0, impl->session_name,
			service_name, NULL, NULL,
			impl->ctrl_port, txt);

	avahi_string_list_free(txt);

	if (res < 0) {
		pw_log_error("can't add service: %s",
			avahi_strerror(avahi_client_errno(impl->client)));
		return -EIO;
	}
	if ((res = avahi_entry_group_commit(impl->group)) < 0) {
		pw_log_error("can't commit group: %s",
			avahi_strerror(avahi_client_errno(impl->client)));
		return -EIO;
	}
	return 0;
}
static void client_callback(AvahiClient *c, AvahiClientState state, void *userdata)
{
	struct impl *impl = userdata;
	impl->client = c;

	switch (state) {
	case AVAHI_CLIENT_S_REGISTERING:
	case AVAHI_CLIENT_S_RUNNING:
	case AVAHI_CLIENT_S_COLLISION:
		make_browser(impl);
		make_announce(impl);
		break;
	case AVAHI_CLIENT_FAILURE:
	case AVAHI_CLIENT_CONNECTING:
		break;
	default:
		break;
	}
}

static void copy_props(struct impl *impl, struct pw_properties *props, const char *key)
{
	const char *str;
	if ((str = pw_properties_get(props, key)) != NULL) {
		if (pw_properties_get(impl->stream_props, key) == NULL)
			pw_properties_set(impl->stream_props, key, str);
	}
}

SPA_EXPORT
int pipewire__module_init(struct pw_impl_module *module, const char *args)
{
	struct pw_context *context = pw_impl_module_get_context(module);
	struct impl *impl;
	struct pw_properties *props = NULL, *stream_props = NULL;
	uint16_t port;
	const char *str;
	int res = 0;

	PW_LOG_TOPIC_INIT(mod_topic);

	impl = calloc(1, sizeof(struct impl));
	if (impl == NULL)
		return -errno;

	if (args == NULL)
		args = "";

	spa_list_init(&impl->sessions);
	spa_list_init(&impl->service_list);

	props = pw_properties_new_string(args);
	if (props == NULL) {
		res = -errno;
		pw_log_error( "can't create properties: %m");
		goto out;
	}
	impl->props = props;

	impl->discover_local =  pw_properties_get_bool(impl->props,
			"sess.discover-local", false);

	stream_props = pw_properties_new(NULL, NULL);
	if (stream_props == NULL) {
		res = -errno;
		pw_log_error( "can't create properties: %m");
		goto out;
	}
	impl->stream_props = stream_props;

	impl->module = module;
	impl->context = context;
	impl->loop = pw_context_get_main_loop(context);
	impl->data_loop = pw_context_acquire_loop(context, &props->dict);
	impl->timer_queue = pw_context_get_timer_queue(context);

	pw_properties_set(props, PW_KEY_NODE_LOOP_NAME, impl->data_loop->name);

	if (pw_properties_get(props, "sess.media") == NULL)
		pw_properties_set(props, "sess.media", "midi");

	if ((str = pw_properties_get(props, "stream.props")) != NULL)
		pw_properties_update_string(stream_props, str, strlen(str));

	copy_props(impl, props, PW_KEY_NODE_LOOP_NAME);
	copy_props(impl, props, PW_KEY_AUDIO_FORMAT);
	copy_props(impl, props, PW_KEY_AUDIO_RATE);
	copy_props(impl, props, PW_KEY_AUDIO_CHANNELS);
	copy_props(impl, props, SPA_KEY_AUDIO_POSITION);
	copy_props(impl, props, PW_KEY_NODE_NAME);
	copy_props(impl, props, PW_KEY_NODE_DESCRIPTION);
	copy_props(impl, props, PW_KEY_NODE_GROUP);
	copy_props(impl, props, PW_KEY_NODE_LATENCY);
	copy_props(impl, props, PW_KEY_NODE_VIRTUAL);
	copy_props(impl, props, PW_KEY_NODE_CHANNELNAMES);
	copy_props(impl, props, PW_KEY_MEDIA_NAME);
	copy_props(impl, props, PW_KEY_MEDIA_CLASS);
	copy_props(impl, props, "net.mtu");
	copy_props(impl, props, "sess.media");
	copy_props(impl, props, "sess.min-ptime");
	copy_props(impl, props, "sess.max-ptime");
	copy_props(impl, props, "sess.latency.msec");
	copy_props(impl, props, "sess.ts-refclk");

	impl->ttl = pw_properties_get_uint32(props, "net.ttl", DEFAULT_TTL);
	impl->mcast_loop = pw_properties_get_bool(props, "net.loop", DEFAULT_LOOP);

	str = pw_properties_get(stream_props, "sess.media");

	if (spa_streq(str, "audio")) {
		struct spa_dict_item items[] = {
			{ "audio.format", DEFAULT_FORMAT },
			{ "audio.rate", SPA_STRINGIFY(DEFAULT_RATE) },
			{ "audio.channels", SPA_STRINGIFY(DEFAULT_CHANNELS) },
			{ "audio.position", DEFAULT_POSITION } };
		pw_properties_add(stream_props, &SPA_DICT_INIT_ARRAY(items));
	}
	else if (spa_streq(str, "opus")) {
		struct spa_dict_item items[] = {
			{ "audio.rate", SPA_STRINGIFY(DEFAULT_RATE) },
			{ "audio.channels", SPA_STRINGIFY(DEFAULT_CHANNELS) },
			{ "audio.position", DEFAULT_POSITION } };
		pw_properties_add(stream_props, &SPA_DICT_INIT_ARRAY(items));
	}

	str = pw_properties_get(props, "local.ifname");
	impl->ifname = str ? strdup(str) : NULL;

	port = pw_properties_get_uint32(props, "control.port", DEFAULT_CONTROL_PORT);
	if ((str = pw_properties_get(props, "control.ip")) == NULL)
		str = DEFAULT_CONTROL_IP;

	impl->ctrl_port = port;

	if ((res = pw_net_parse_address(str, port, &impl->ctrl_addr, &impl->ctrl_len)) < 0) {
		pw_log_error("invalid control.ip %s: %s", str, spa_strerror(res));
		goto out;
	}
	if ((res = pw_net_parse_address(str, port ? port+1 : 0, &impl->data_addr, &impl->data_len)) < 0) {
		pw_log_error("invalid data.ip %s: %s", str, spa_strerror(res));
		goto out;
	}

	impl->ts_offset = pw_properties_get_int64(props,
			"sess.ts-offset", pw_rand32());
	str = pw_properties_get(props, "sess.ts-refclk");
	impl->ts_refclk = str ? strdup(str) : NULL;

	if ((str = pw_properties_get(props, "sess.name")) == NULL)
		pw_properties_setf(props, "sess.name", "%s", pw_get_host_name());
	str = pw_properties_get(props, "sess.name");
	impl->session_name = str ? strdup(str) : NULL;

	impl->core = pw_context_get_object(impl->context, PW_TYPE_INTERFACE_Core);
	if (impl->core == NULL) {
		str = pw_properties_get(props, PW_KEY_REMOTE_NAME);
		impl->core = pw_context_connect(impl->context,
				pw_properties_new(
					PW_KEY_REMOTE_NAME, str,
					NULL),
				0);
		impl->do_disconnect = true;
	}
	if (impl->core == NULL) {
		res = -errno;
		pw_log_error("can't connect: %m");
		goto out;
	}

	pw_proxy_add_listener((struct pw_proxy*)impl->core,
			&impl->core_proxy_listener,
			&core_proxy_events, impl);
	pw_core_add_listener(impl->core,
			&impl->core_listener,
			&core_events, impl);

	if ((res = setup_apple_session(impl)) < 0)
		goto out;

	impl->avahi_poll = pw_avahi_poll_new(impl->context);
	if ((impl->client = avahi_client_new(impl->avahi_poll,
					AVAHI_CLIENT_NO_FAIL,
					client_callback, impl,
					&res)) == NULL) {
		pw_log_error("can't create avahi client: %s", avahi_strerror(res));
		goto out;
	}

	pw_impl_module_add_listener(module, &impl->module_listener, &module_events, impl);

	pw_impl_module_update_properties(module, &SPA_DICT_INIT_ARRAY(module_info));

	return 0;
out:
	impl_destroy(impl);
	return res;
}