chan_sip.c

	/*
	 * We cannot let the stream exclusively wait for data to arrive.
	 * We have to wake up the task to send outgoing messages.
	 */
	ast_tcptls_stream_set_exclusive_input(tcptls_session->stream_cookie, 0);

	ast_tcptls_stream_set_timeout_sequence(tcptls_session->stream_cookie, ast_tvnow(),
		tcptls_session->client ? -1 : (authtimeout * 1000));

	for (;;) {
		struct ast_str *str_save;

		if (!tcptls_session->client && req.authenticated && !authenticated) {
			authenticated = 1;
			ast_tcptls_stream_set_timeout_disable(tcptls_session->stream_cookie);
			ast_atomic_fetchadd_int(&unauth_sessions, -1);
		}

		/* calculate the timeout for unauthenticated server sessions */
		if (!tcptls_session->client && !authenticated ) {
			if ((timeout = sip_check_authtimeout(start)) < 0) {
				goto cleanup;
			}

			if (timeout == 0) {
				ast_debug(2, "SIP %s server timed out\n", tcptls_session->ssl ? "TLS": "TCP");
				goto cleanup;
			}
		} else {
			timeout = -1;
		}

		if (ast_str_strlen(tcptls_session->overflow_buf) == 0) {
			res = ast_poll(fds, 2, timeout); /* polls for both socket and alert_pipe */
			if (res < 0) {
				ast_debug(2, "SIP %s server :: ast_wait_for_input returned %d\n", tcptls_session->ssl ? "TLS": "TCP", res);
				goto cleanup;
			} else if (res == 0) {
				/* timeout */
				ast_debug(2, "SIP %s server timed out\n", tcptls_session->ssl ? "TLS": "TCP");
				goto cleanup;
			}
		}

		/*
		 * handle the socket event, check for both reads from the socket fd or TCP overflow buffer,
		 * and writes from alert_pipe fd.
		 */
		if (fds[0].revents || (ast_str_strlen(tcptls_session->overflow_buf) > 0)) { /* there is data on the socket to be read */
			fds[0].revents = 0;

			/* clear request structure */
			str_save = req.data;
			memset(&req, 0, sizeof(req));
			req.data = str_save;
			ast_str_reset(req.data);

			str_save = reqcpy.data;
			memset(&reqcpy, 0, sizeof(reqcpy));
			reqcpy.data = str_save;
			ast_str_reset(reqcpy.data);

			memset(buf, 0, sizeof(buf));

			if (tcptls_session->ssl) {
				set_socket_transport(&req.socket, AST_TRANSPORT_TLS);
				req.socket.port = htons(ourport_tls);
			} else {
				set_socket_transport(&req.socket, AST_TRANSPORT_TCP);
				req.socket.port = htons(ourport_tcp);
			}
			req.socket.fd = tcptls_session->fd;

			res = sip_tcptls_read(&req, tcptls_session, authenticated, start);
			if (res < 0) {
				goto cleanup;
			}

			req.socket.tcptls_session = tcptls_session;
			req.socket.ws_session = NULL;
			handle_request_do(&req, &tcptls_session->remote_address);
		}

		if (fds[1].revents) { /* alert_pipe indicates there is data in the send queue to be sent */
			enum sip_tcptls_alert alert;
			struct tcptls_packet *packet;

			fds[1].revents = 0;

			if (read(me->alert_pipe[0], &alert, sizeof(alert)) == -1) {
				ast_log(LOG_ERROR, "read() failed: %s\n", strerror(errno));
				continue;
			}

			switch (alert) {
			case TCPTLS_ALERT_STOP:
				goto cleanup;
			case TCPTLS_ALERT_DATA:
				ao2_lock(me);
				if (!(packet = AST_LIST_REMOVE_HEAD(&me->packet_q, entry))) {
					ast_log(LOG_WARNING, "TCPTLS thread alert_pipe indicated packet should be sent, but frame_q is empty\n");
				}
				ao2_unlock(me);

				if (packet) {
					if (ast_tcptls_server_write(tcptls_session, ast_str_buffer(packet->data), packet->len) == -1) {
						ast_log(LOG_WARNING, "Failure to write to tcp/tls socket\n");
					}
					ao2_t_ref(packet, -1, "tcptls packet sent, this is no longer needed");
				}
				break;
			default:
				ast_log(LOG_ERROR, "Unknown tcptls thread alert '%u'\n", alert);
			}
		}
	}

	ast_debug(2, "Shutting down thread for %s server\n", tcptls_session->ssl ? "TLS" : "TCP");

cleanup:
	if (tcptls_session && !tcptls_session->client && !authenticated) {
		ast_atomic_fetchadd_int(&unauth_sessions, -1);
	}

	if (me) {
		ao2_t_unlink(threadt, me, "Removing tcptls helper thread, thread is closing");
		ao2_t_ref(me, -1, "Removing tcp_helper_threads threadinfo ref");
	}
	deinit_req(&reqcpy);
	deinit_req(&req);

	/* if client, we own the parent session arguments and must decrement ref */
	if (ca) {
		ao2_t_ref(ca, -1, "closing tcptls thread, getting rid of client tcptls_session arguments");
	}

	if (tcptls_session) {
		ao2_lock(tcptls_session);
		ast_tcptls_close_session_file(tcptls_session);
		tcptls_session->parent = NULL;
		ao2_unlock(tcptls_session);

		ao2_ref(tcptls_session, -1);
		tcptls_session = NULL;
	}
	return NULL;
}

static void peer_sched_cleanup(struct sip_peer *peer)
{
	if (peer->pokeexpire != -1) {
		AST_SCHED_DEL_UNREF(sched, peer->pokeexpire,
				sip_unref_peer(peer, "removing poke peer ref"));
	}
	if (peer->expire != -1) {
		AST_SCHED_DEL_UNREF(sched, peer->expire,
				sip_unref_peer(peer, "remove register expire ref"));
	}
	if (peer->keepalivesend != -1) {
		AST_SCHED_DEL_UNREF(sched, peer->keepalivesend,
				    sip_unref_peer(peer, "remove keepalive peer ref"));
	}
}

typedef enum {
	SIP_PEERS_MARKED,
	SIP_PEERS_ALL,
} peer_unlink_flag_t;

/* this func is used with ao2_callback to unlink/delete all marked or linked
   peers, depending on arg */
static int match_and_cleanup_peer_sched(void *peerobj, void *arg, int flags)
{
	struct sip_peer *peer = peerobj;
	peer_unlink_flag_t which = *(peer_unlink_flag_t *)arg;

	if (which == SIP_PEERS_ALL || peer->the_mark) {
		peer_sched_cleanup(peer);
		if (peer->dnsmgr) {
			ast_dnsmgr_release(peer->dnsmgr);
			peer->dnsmgr = NULL;
			sip_unref_peer(peer, "Release peer from dnsmgr");
		}
		return CMP_MATCH;
	}
	return 0;
}

static void unlink_peers_from_tables(peer_unlink_flag_t flag)
{
	struct ao2_iterator *peers_iter;

	/*
	 * We must remove the ref outside of the peers container to prevent
	 * a deadlock condition when unsubscribing from stasis while it is
	 * invoking a subscription event callback.
	 */
	peers_iter = ao2_t_callback(peers, OBJ_UNLINK | OBJ_MULTIPLE,
		match_and_cleanup_peer_sched, &flag, "initiating callback to remove marked peers");
	if (peers_iter) {
		ao2_iterator_destroy(peers_iter);
	}

	peers_iter = ao2_t_callback(peers_by_ip, OBJ_UNLINK | OBJ_MULTIPLE,
		match_and_cleanup_peer_sched, &flag, "initiating callback to remove marked peers_by_ip");
	if (peers_iter) {
		ao2_iterator_destroy(peers_iter);
	}
}

/* \brief Unlink all marked peers from ao2 containers */
static void unlink_marked_peers_from_tables(void)
{
	unlink_peers_from_tables(SIP_PEERS_MARKED);
}

static void unlink_all_peers_from_tables(void)
{
	unlink_peers_from_tables(SIP_PEERS_ALL);
}

/*! \brief maintain proper refcounts for a sip_pvt's outboundproxy
 *
 * This function sets pvt's outboundproxy pointer to the one referenced
 * by the proxy parameter. Because proxy may be a refcounted object, and
 * because pvt's old outboundproxy may also be a refcounted object, we need
 * to maintain the proper refcounts.
 *
 * \param pvt The sip_pvt for which we wish to set the outboundproxy
 * \param proxy The sip_proxy which we will point pvt towards.
 * \return Returns void
 */
static void ref_proxy(struct sip_pvt *pvt, struct sip_proxy *proxy)
{
	struct sip_proxy *old_obproxy = pvt->outboundproxy;
	/* The sip_cfg.outboundproxy is statically allocated, and so
	 * we don't ever need to adjust refcounts for it
	 */
	if (proxy && proxy != &sip_cfg.outboundproxy) {
		ao2_ref(proxy, +1);
	}
	pvt->outboundproxy = proxy;
	if (old_obproxy && old_obproxy != &sip_cfg.outboundproxy) {
		ao2_ref(old_obproxy, -1);
	}
}

static void do_dialog_unlink_sched_items(struct sip_pvt *dialog)
{
	struct sip_pkt *cp;

	/* remove all current packets in this dialog */
	sip_pvt_lock(dialog);
	while ((cp = dialog->packets)) {
		/* Unlink and destroy the packet object. */
		dialog->packets = dialog->packets->next;
		AST_SCHED_DEL_UNREF(sched, cp->retransid,
			ao2_t_ref(cp, -1, "Stop scheduled packet retransmission"));
		ao2_t_ref(cp, -1, "Packet retransmission list");
	}
	sip_pvt_unlock(dialog);

	AST_SCHED_DEL_UNREF(sched, dialog->waitid,
		dialog_unref(dialog, "Stop scheduled waitid"));

	AST_SCHED_DEL_UNREF(sched, dialog->initid,
		dialog_unref(dialog, "Stop scheduled initid"));

	AST_SCHED_DEL_UNREF(sched, dialog->reinviteid,
		dialog_unref(dialog, "Stop scheduled reinviteid"));

	AST_SCHED_DEL_UNREF(sched, dialog->autokillid,
		dialog_unref(dialog, "Stop scheduled autokillid"));

	AST_SCHED_DEL_UNREF(sched, dialog->request_queue_sched_id,
		dialog_unref(dialog, "Stop scheduled request_queue_sched_id"));

	AST_SCHED_DEL_UNREF(sched, dialog->provisional_keepalive_sched_id,
		dialog_unref(dialog, "Stop scheduled provisional keepalive"));

	AST_SCHED_DEL_UNREF(sched, dialog->t38id,
		dialog_unref(dialog, "Stop scheduled t38id"));

	if (dialog->stimer) {
		dialog->stimer->st_active = FALSE;
		do_stop_session_timer(dialog);
	}
}

/* Run by the sched thread. */
static int __dialog_unlink_sched_items(const void *data)
{
	struct sip_pvt *dialog = (void *) data;

	do_dialog_unlink_sched_items(dialog);
	dialog_unref(dialog, "Stop scheduled items for unlink action");
	return 0;
}

/*!
 * \brief Unlink a dialog from the dialogs container, as well as any other places
 * that it may be currently stored.
 *
 * \note A reference to the dialog must be held before calling this function, and this
 * function does not release that reference.
 */
void dialog_unlink_all(struct sip_pvt *dialog)
{
	struct ast_channel *owner;

	dialog_ref(dialog, "Let's bump the count in the unlink so it doesn't accidentally become dead before we are done");

	ao2_t_unlink(dialogs, dialog, "unlinking dialog via ao2_unlink");
	ao2_t_unlink(dialogs_needdestroy, dialog, "unlinking dialog_needdestroy via ao2_unlink");
	ao2_t_unlink(dialogs_rtpcheck, dialog, "unlinking dialog_rtpcheck via ao2_unlink");

	/* Unlink us from the owner (channel) if we have one */
	owner = sip_pvt_lock_full(dialog);
	if (owner) {
		ast_debug(1, "Detaching from channel %s\n", ast_channel_name(owner));
		ast_channel_tech_pvt_set(owner, dialog_unref(ast_channel_tech_pvt(owner), "resetting channel dialog ptr in unlink_all"));
		ast_channel_unlock(owner);
		ast_channel_unref(owner);
		sip_set_owner(dialog, NULL);
	}
	sip_pvt_unlock(dialog);

	if (dialog->registry) {
		if (dialog->registry->call == dialog) {
			dialog->registry->call = dialog_unref(dialog->registry->call, "nulling out the registry's call dialog field in unlink_all");
		}
		ao2_t_replace(dialog->registry, NULL, "delete dialog->registry");
	}
	if (dialog->stateid != -1) {
		ast_extension_state_del(dialog->stateid, cb_extensionstate);
		dialog->stateid = -1;
	}
	/* Remove link from peer to subscription of MWI */
	if (dialog->relatedpeer && dialog->relatedpeer->mwipvt == dialog) {
		dialog->relatedpeer->mwipvt = dialog_unref(dialog->relatedpeer->mwipvt, "delete ->relatedpeer->mwipvt");
	}
	if (dialog->relatedpeer && dialog->relatedpeer->call == dialog) {
		dialog->relatedpeer->call = dialog_unref(dialog->relatedpeer->call, "unset the relatedpeer->call field in tandem with relatedpeer field itself");
	}

	dialog_ref(dialog, "Stop scheduled items for unlink action");
	if (ast_sched_add(sched, 0, __dialog_unlink_sched_items, dialog) < 0) {
		/*
		 * Uh Oh.  Fall back to unscheduling things immediately
		 * despite the potential deadlock risk.
		 */
		dialog_unref(dialog, "Failed to schedule stop scheduled items for unlink action");
		do_dialog_unlink_sched_items(dialog);
	}

	dialog_unref(dialog, "Let's unbump the count in the unlink so the poor pvt can disappear if it is time");
}

static void append_history_full(struct sip_pvt *p, const char *fmt, ...)
	__attribute__((format(printf, 2, 3)));


/*! \brief Convert transfer status to string */
static const char *referstatus2str(enum referstatus rstatus)
{
	return map_x_s(referstatusstrings, rstatus, "");
}

static inline void pvt_set_needdestroy(struct sip_pvt *pvt, const char *reason)
{
	if (pvt->final_destruction_scheduled) {
		return; /* This is already scheduled for final destruction, let the scheduler take care of it. */
	}
	append_history(pvt, "NeedDestroy", "Setting needdestroy because %s", reason);
	if (!pvt->needdestroy) {
		pvt->needdestroy = 1;
		ao2_t_link(dialogs_needdestroy, pvt, "link pvt into dialogs_needdestroy container");
	}
}

/*! \brief Initialize the initital request packet in the pvt structure.
	This packet is used for creating replies and future requests in
	a dialog */
static void initialize_initreq(struct sip_pvt *p, struct sip_request *req)
{
	if (p->initreq.headers) {
		ast_debug(1, "Initializing already initialized SIP dialog %s (presumably reinvite)\n", p->callid);
	} else {
		ast_debug(1, "Initializing initreq for method %s - callid %s\n", sip_methods[req->method].text, p->callid);
	}
	/* Use this as the basis */
	copy_request(&p->initreq, req);
	parse_request(&p->initreq);
	if (req->debug) {
		ast_verbose("Initreq: %d headers, %d lines\n", p->initreq.headers, p->initreq.lines);
	}
}

/*! \brief Encapsulate setting of SIP_ALREADYGONE to be able to trace it with debugging */
static void sip_alreadygone(struct sip_pvt *dialog)
{
	ast_debug(3, "Setting SIP_ALREADYGONE on dialog %s\n", dialog->callid);
	dialog->alreadygone = 1;
}

/*! Resolve DNS srv name or host name in a sip_proxy structure */
static int proxy_update(struct sip_proxy *proxy)
{
	/* if it's actually an IP address and not a name,
           there's no need for a managed lookup */
	if (!ast_sockaddr_parse(&proxy->ip, proxy->name, 0)) {
		/* Ok, not an IP address, then let's check if it's a domain or host */
		/* XXX Todo - if we have proxy port, don't do SRV */
		proxy->ip.ss.ss_family = get_address_family_filter(AST_TRANSPORT_UDP); /* Filter address family */
		if (ast_get_ip_or_srv(&proxy->ip, proxy->name, sip_cfg.srvlookup ? "_sip._udp" : NULL) < 0) {
				ast_log(LOG_WARNING, "Unable to locate host '%s'\n", proxy->name);
				return FALSE;
		}

	}

	ast_sockaddr_set_port(&proxy->ip, proxy->port);

	proxy->last_dnsupdate = time(NULL);
	return TRUE;
}

/*! \brief Parse proxy string and return an ao2_alloc'd proxy. If dest is
 *         non-NULL, no allocation is performed and dest is used instead.
 *         On error NULL is returned. */
static struct sip_proxy *proxy_from_config(const char *proxy, int sipconf_lineno, struct sip_proxy *dest)
{
	char *mutable_proxy, *sep, *name;
	int allocated = 0;

	if (!dest) {
		dest = ao2_alloc(sizeof(struct sip_proxy), NULL);
		if (!dest) {
			ast_log(LOG_WARNING, "Unable to allocate config storage for proxy\n");
			return NULL;
		}
		allocated = 1;
	}

	/* Format is: [transport://]name[:port][,force] */
	mutable_proxy = ast_skip_blanks(ast_strdupa(proxy));
	sep = strchr(mutable_proxy, ',');
	if (sep) {
		*sep++ = '\0';
		dest->force = !strncasecmp(ast_skip_blanks(sep), "force", 5);
	} else {
		dest->force = FALSE;
	}

	sip_parse_host(mutable_proxy, sipconf_lineno, &name, &dest->port, &dest->transport);

	/* Check that there is a name at all */
	if (ast_strlen_zero(name)) {
		if (allocated) {
			ao2_ref(dest, -1);
		} else {
			dest->name[0] = '\0';
		}
		return NULL;
	}
	ast_copy_string(dest->name, name, sizeof(dest->name));

	/* Resolve host immediately */
	proxy_update(dest);

	return dest;
}

/*! \brief converts ascii port to int representation. If no
 *  pt buffer is provided or the pt has errors when being converted
 *  to an int value, the port provided as the standard is used.
 */
unsigned int port_str2int(const char *pt, unsigned int standard)
{
	int port = standard;
	if (ast_strlen_zero(pt) || (sscanf(pt, "%30d", &port) != 1) || (port < 1) || (port > 65535)) {
		port = standard;
	}

	return port;
}

/*! \brief Get default outbound proxy or global proxy */
static struct sip_proxy *obproxy_get(struct sip_pvt *dialog, struct sip_peer *peer)
{
	if (dialog && dialog->options && dialog->options->outboundproxy) {
		if (sipdebug) {
			ast_debug(1, "OBPROXY: Applying dialplan set OBproxy to this call\n");
		}
		append_history(dialog, "OBproxy", "Using dialplan obproxy %s", dialog->options->outboundproxy->name);
		return dialog->options->outboundproxy;
	}
	if (peer && peer->outboundproxy) {
		if (sipdebug) {
			ast_debug(1, "OBPROXY: Applying peer OBproxy to this call\n");
		}
		append_history(dialog, "OBproxy", "Using peer obproxy %s", peer->outboundproxy->name);
		return peer->outboundproxy;
	}
	if (sip_cfg.outboundproxy.name[0]) {
		if (sipdebug) {
			ast_debug(1, "OBPROXY: Applying global OBproxy to this call\n");
		}
		append_history(dialog, "OBproxy", "Using global obproxy %s", sip_cfg.outboundproxy.name);
		return &sip_cfg.outboundproxy;
	}
	if (sipdebug) {
		ast_debug(1, "OBPROXY: Not applying OBproxy to this call\n");
	}
	return NULL;
}

/*! \brief returns true if 'name' (with optional trailing whitespace)
 * matches the sip method 'id'.
 * Strictly speaking, SIP methods are case SENSITIVE, but we do
 * a case-insensitive comparison to be more tolerant.
 * following Jon Postel's rule: Be gentle in what you accept, strict with what you send
 */
static int method_match(enum sipmethod id, const char *name)
{
	int len = strlen(sip_methods[id].text);
	int l_name = name ? strlen(name) : 0;
	/* true if the string is long enough, and ends with whitespace, and matches */
	return (l_name >= len && name && name[len] < 33 &&
		!strncasecmp(sip_methods[id].text, name, len));
}

/*! \brief  find_sip_method: Find SIP method from header */
static int find_sip_method(const char *msg)
{
	int i, res = 0;

	if (ast_strlen_zero(msg)) {
		return 0;
	}
	for (i = 1; i < ARRAY_LEN(sip_methods) && !res; i++) {
		if (method_match(i, msg)) {
			res = sip_methods[i].id;
		}
	}
	return res;
}

/*! \brief See if we pass debug IP filter */
static inline int sip_debug_test_addr(const struct ast_sockaddr *addr)
{
	/* Can't debug if sipdebug is not enabled */
	if (!sipdebug) {
		return 0;
	}

	/* A null debug_addr means we'll debug any address */
	if (ast_sockaddr_isnull(&debugaddr)) {
		return 1;
	}

	/* If no port was specified for a debug address, just compare the
	 * addresses, otherwise compare the address and port
	 */
	if (ast_sockaddr_port(&debugaddr)) {
		return !ast_sockaddr_cmp(&debugaddr, addr);
	} else {
		return !ast_sockaddr_cmp_addr(&debugaddr, addr);
	}
}

/*! \brief The real destination address for a write */
static const struct ast_sockaddr *sip_real_dst(const struct sip_pvt *p)
{
	if (p->outboundproxy) {
		return &p->outboundproxy->ip;
	}

	return ast_test_flag(&p->flags[0], SIP_NAT_FORCE_RPORT) || ast_test_flag(&p->flags[0], SIP_NAT_RPORT_PRESENT) ? &p->recv : &p->sa;
}

/*! \brief Display SIP nat mode */
static const char *sip_nat_mode(const struct sip_pvt *p)
{
	return ast_test_flag(&p->flags[0], SIP_NAT_FORCE_RPORT) ? "NAT" : "no NAT";
}

/*! \brief Test PVT for debugging output */
static inline int sip_debug_test_pvt(struct sip_pvt *p)
{
	if (!sipdebug) {
		return 0;
	}
	return sip_debug_test_addr(sip_real_dst(p));
}

/*! \brief Return int representing a bit field of transport types found in const char *transport */
static int get_transport_str2enum(const char *transport)
{
	int res = 0;

	if (ast_strlen_zero(transport)) {
		return res;
	}

	if (!strcasecmp(transport, "udp")) {
		res |= AST_TRANSPORT_UDP;
	}
	if (!strcasecmp(transport, "tcp")) {
		res |= AST_TRANSPORT_TCP;
	}
	if (!strcasecmp(transport, "tls")) {
		res |= AST_TRANSPORT_TLS;
	}
	if (!strcasecmp(transport, "ws")) {
		res |= AST_TRANSPORT_WS;
	}
	if (!strcasecmp(transport, "wss")) {
		res |= AST_TRANSPORT_WSS;
	}

	return res;
}

/*! \brief Return configuration of transports for a device */
static inline const char *get_transport_list(unsigned int transports)
{
	char *buf;

	if (!transports) {
		return "UNKNOWN";
	}

	if (!(buf = ast_threadstorage_get(&sip_transport_str_buf, SIP_TRANSPORT_STR_BUFSIZE))) {
		return "";
	}

	memset(buf, 0, SIP_TRANSPORT_STR_BUFSIZE);

	if (transports & AST_TRANSPORT_UDP) {
		strncat(buf, "UDP,", SIP_TRANSPORT_STR_BUFSIZE - strlen(buf));
	}
	if (transports & AST_TRANSPORT_TCP) {
		strncat(buf, "TCP,", SIP_TRANSPORT_STR_BUFSIZE - strlen(buf));
	}
	if (transports & AST_TRANSPORT_TLS) {
		strncat(buf, "TLS,", SIP_TRANSPORT_STR_BUFSIZE - strlen(buf));
	}
	if (transports & AST_TRANSPORT_WS) {
		strncat(buf, "WS,", SIP_TRANSPORT_STR_BUFSIZE - strlen(buf));
	}
	if (transports & AST_TRANSPORT_WSS) {
		strncat(buf, "WSS,", SIP_TRANSPORT_STR_BUFSIZE - strlen(buf));
	}

	/* Remove the trailing ',' if present */
	if (strlen(buf)) {
		buf[strlen(buf) - 1] = 0;
	}

	return buf;
}

/*! \brief Return transport as string */
const char *sip_get_transport(enum ast_transport t)
{
	switch (t) {
	case AST_TRANSPORT_UDP:
		return "UDP";
	case AST_TRANSPORT_TCP:
		return "TCP";
	case AST_TRANSPORT_TLS:
		return "TLS";
	case AST_TRANSPORT_WS:
	case AST_TRANSPORT_WSS:
		return "WS";
	}

	return "UNKNOWN";
}

/*! \brief Return protocol string for srv dns query */
static inline const char *get_srv_protocol(enum ast_transport t)
{
	switch (t) {
	case AST_TRANSPORT_UDP:
		return "udp";
	case AST_TRANSPORT_WS:
		return "ws";
	case AST_TRANSPORT_TLS:
	case AST_TRANSPORT_TCP:
		return "tcp";
	case AST_TRANSPORT_WSS:
		return "wss";
	}

	return "udp";
}

/*! \brief Return service string for srv dns query */
static inline const char *get_srv_service(enum ast_transport t)
{
	switch (t) {
	case AST_TRANSPORT_TCP:
	case AST_TRANSPORT_UDP:
	case AST_TRANSPORT_WS:
		return "sip";
	case AST_TRANSPORT_TLS:
	case AST_TRANSPORT_WSS:
		return "sips";
	}
	return "sip";
}

/*! \brief Return transport of dialog.
	\note this is based on a false assumption. We don't always use the
	outbound proxy for all requests in a dialog. It depends on the
	"force" parameter. The FIRST request is always sent to the ob proxy.
	\todo Fix this function to work correctly
*/
static inline const char *get_transport_pvt(struct sip_pvt *p)
{
	if (p->outboundproxy && p->outboundproxy->transport) {
		set_socket_transport(&p->socket, p->outboundproxy->transport);
	}

	return sip_get_transport(p->socket.type);
}

/*!
 * \internal
 * \brief Transmit SIP message
 *
 * \details
 * Sends a SIP request or response on a given socket (in the pvt)
 * \note
 * Called by retrans_pkt, send_request, send_response and __sip_reliable_xmit
 *
 * \return length of transmitted message, XMIT_ERROR on known network failures -1 on other failures.
 */
static int __sip_xmit(struct sip_pvt *p, struct ast_str *data)
{
	int res = 0;
	const struct ast_sockaddr *dst = sip_real_dst(p);

	ast_debug(2, "Trying to put '%.11s' onto %s socket destined for %s\n", ast_str_buffer(data), get_transport_pvt(p), ast_sockaddr_stringify(dst));

	if (sip_prepare_socket(p) < 0) {
		return XMIT_ERROR;
	}

	if (p->socket.type == AST_TRANSPORT_UDP) {
		res = ast_sendto(p->socket.fd, ast_str_buffer(data), ast_str_strlen(data), 0, dst);
	} else if (p->socket.tcptls_session) {
		res = sip_tcptls_write(p->socket.tcptls_session, ast_str_buffer(data), ast_str_strlen(data));
	} else if (p->socket.ws_session) {
		if (!(res = ast_websocket_write_string(p->socket.ws_session, ast_str_buffer(data)))) {
			/* The WebSocket API just returns 0 on success and -1 on failure, while this code expects the payload length to be returned */
			res = ast_str_strlen(data);
		}
	} else {
		ast_debug(2, "Socket type is TCP but no tcptls_session is present to write to\n");
		return XMIT_ERROR;
	}

	if (res == -1) {
		switch (errno) {
		case EBADF:		/* Bad file descriptor - seems like this is generated when the host exist, but doesn't accept the UDP packet */
		case EHOSTUNREACH:	/* Host can't be reached */
		case ENETDOWN:		/* Interface down */
		case ENETUNREACH:	/* Network failure */
		case ECONNREFUSED:      /* ICMP port unreachable */
			res = XMIT_ERROR;	/* Don't bother with trying to transmit again */
		}
	}
	if (res != ast_str_strlen(data)) {
		ast_log(LOG_WARNING, "sip_xmit of %p (len %zu) to %s returned %d: %s\n", data, ast_str_strlen(data), ast_sockaddr_stringify(dst), res, strerror(errno));
	}

	return res;
}

/*! \brief Build a Via header for a request */
static void build_via(struct sip_pvt *p)
{
	/* Work around buggy UNIDEN UIP200 firmware */
	const char *rport = (ast_test_flag(&p->flags[0], SIP_NAT_FORCE_RPORT) || ast_test_flag(&p->flags[0], SIP_NAT_RPORT_PRESENT)) ? ";rport" : "";

	/* z9hG4bK is a magic cookie.  See RFC 3261 section 8.1.1.7 */
	snprintf(p->via, sizeof(p->via), "SIP/2.0/%s %s;branch=z9hG4bK%08x%s",
		 get_transport_pvt(p),
		 ast_sockaddr_stringify_remote(&p->ourip),
		 (unsigned)p->branch, rport);
}

/*! \brief NAT fix - decide which IP address to use for Asterisk server?
 *
 * Using the localaddr structure built up with localnet statements in sip.conf
 * apply it to their address to see if we need to substitute our
 * externaddr or can get away with our internal bindaddr
 * 'us' is always overwritten.
 */
static void ast_sip_ouraddrfor(const struct ast_sockaddr *them, struct ast_sockaddr *us, struct sip_pvt *p)
{
	struct ast_sockaddr theirs;

	/* Set want_remap to non-zero if we want to remap 'us' to an externally
	 * reachable IP address and port. This is done if:
	 * 1. we have a localaddr list (containing 'internal' addresses marked
	 *    as 'deny', so ast_apply_ha() will return AST_SENSE_DENY on them,
	 *    and AST_SENSE_ALLOW on 'external' ones);
	 * 2. externaddr is set, so we know what to use as the
	 *    externally visible address;
	 * 3. the remote address, 'them', is external;
	 * 4. the address returned by ast_ouraddrfor() is 'internal' (AST_SENSE_DENY
	 *    when passed to ast_apply_ha() so it does need to be remapped.
	 *    This fourth condition is checked later.
	 */
	int want_remap = 0;

	ast_sockaddr_copy(us, &internip); /* starting guess for the internal address */
	/* now ask the system what would it use to talk to 'them' */
	ast_ouraddrfor(them, us);
	ast_sockaddr_copy(&theirs, them);

	if (ast_sockaddr_is_ipv6(&theirs) && !ast_sockaddr_is_ipv4_mapped(&theirs)) {
		if (localaddr && !ast_sockaddr_isnull(&externaddr) && !ast_sockaddr_is_any(&bindaddr)) {
			ast_log(LOG_WARNING, "Address remapping activated in sip.conf "
				"but we're using IPv6, which doesn't need it. Please "
				"remove \"localnet\" and/or \"externaddr\" settings.\n");
		}
	} else {
		want_remap = localaddr &&
			!ast_sockaddr_isnull(&externaddr) &&
			ast_apply_ha(localaddr, &theirs) == AST_SENSE_ALLOW ;
	}

	if (want_remap &&
	    (!sip_cfg.matchexternaddrlocally || !ast_apply_ha(localaddr, us)) ) {
		/* if we used externhost, see if it is time to refresh the info */
		if (externexpire && time(NULL) >= externexpire) {
			if (ast_sockaddr_resolve_first_af(&externaddr, externhost, 0, AST_AF_INET)) {
				ast_log(LOG_NOTICE, "Warning: Re-lookup of '%s' failed!\n", externhost);
			}
			externexpire = time(NULL) + externrefresh;
		}
		if (!ast_sockaddr_isnull(&externaddr)) {
			ast_sockaddr_copy(us, &externaddr);
			switch (p->socket.type) {
			case AST_TRANSPORT_TCP:
				if (!externtcpport && ast_sockaddr_port(&externaddr)) {
					/* for consistency, default to the externaddr port */
					externtcpport = ast_sockaddr_port(&externaddr);
				}
				ast_sockaddr_set_port(us, externtcpport);
				break;
			case AST_TRANSPORT_TLS:
				ast_sockaddr_set_port(us, externtlsport);
				break;
			case AST_TRANSPORT_UDP:
				if (!ast_sockaddr_port(&externaddr)) {
					ast_sockaddr_set_port(us, ast_sockaddr_port(&bindaddr));
				}
				break;
			default:
				break;
			}
		}
		ast_debug(1, "Target address %s is not local, substituting externaddr\n",
			  ast_sockaddr_stringify(them));
	} else {
		/* no remapping, but we bind to a specific address, so use it. */
		switch (p->socket.type) {
		case AST_TRANSPORT_TCP:
			if (!ast_sockaddr_is_any(&sip_tcp_desc.local_address)) {
				ast_sockaddr_copy(us,
						  &sip_tcp_desc.local_address);
			} else {
				ast_sockaddr_set_port(us,
						      ast_sockaddr_port(&sip_tcp_desc.local_address));
			}
			break;
		case AST_TRANSPORT_TLS:
			if (!ast_sockaddr_is_any(&sip_tls_desc.local_address)) {
				ast_sockaddr_copy(us,
						  &sip_tls_desc.local_address);
			} else {
				ast_sockaddr_set_port(us,
						      ast_sockaddr_port(&sip_tls_desc.local_address));
			}
			break;
		case AST_TRANSPORT_UDP:
			/* fall through on purpose */
		default:
			if (!ast_sockaddr_is_any(&bindaddr)) {
				ast_sockaddr_copy(us, &bindaddr);
			}
			if (!ast_sockaddr_port(us)) {
				ast_sockaddr_set_port(us, ast_sockaddr_port(&bindaddr));
			}
		}
	}
	ast_debug(3, "Setting AST_TRANSPORT_%s with address %s\n", sip_get_transport(p->socket.type), ast_sockaddr_stringify(us));
}

/*! \brief Append to SIP dialog history with arg list  */
static __attribute__((format(printf, 2, 0))) void append_history_va(struct sip_pvt *p, const char *fmt, va_list ap)
{
	char buf[80], *c = buf; /* max history length */
	struct sip_history *hist;
	int l;

	vsnprintf(buf, sizeof(buf), fmt, ap);
	strsep(&c, "\r\n"); /* Trim up everything after \r or \n */
	l = strlen(buf) + 1;
	if (!(hist = ast_calloc(1, sizeof(*hist) + l))) {
		return;
	}
	if (!p->history && !(p->history = ast_calloc(1, sizeof(*p->history)))) {
		ast_free(hist);
		return;
	}
	memcpy(hist->event, buf, l);
	if (p->history_entries == MAX_HISTORY_ENTRIES) {
		struct sip_history *oldest;
		oldest = AST_LIST_REMOVE_HEAD(p->history, list);
		p->history_entries--;
		ast_free(oldest);
	}
	AST_LIST_INSERT_TAIL(p->history, hist, list);
	p->history_entries++;
	if (log_level != -1) {
		ast_log_dynamic_level(log_level, "%s\n", buf);
	}
}

/*! \brief Append to SIP dialog history with arg list  */
static void append_history_full(struct sip_pvt *p, const char *fmt, ...)
{
	va_list ap;

	if (!p) {
		return;
	}

	if (!p->do_history && !recordhistory && !dumphistory) {
		return;
	}

	va_start(ap, fmt);
	append_history_va(p, fmt, ap);
	va_end(ap);

	return;
}

/*!
 * \brief Retransmit SIP message if no answer
 *
 * \note Run by the sched thread.
 */
static int retrans_pkt(const void *data)
{
	struct sip_pkt *pkt = (struct sip_pkt *) data;
	struct sip_pkt *prev;
	struct sip_pkt *cur;
	struct ast_channel *owner_chan;
	int reschedule = DEFAULT_RETRANS;
	int xmitres = 0;
	/* how many ms until retrans timeout is reached */
	int64_t diff = pkt->retrans_stop_time - ast_tvdiff_ms(ast_tvnow(), pkt->time_sent);

	/* Do not retransmit if time out is reached. This will be negative if the time between
	 * the first transmission and now is larger than our timeout period. This is a fail safe
	 * check in case the scheduler gets behind or the clock is changed. */
	if ((diff <= 0) || (diff > pkt->retrans_stop_time)) {
		pkt->retrans_stop = 1;
	}

	/* Lock channel PVT */
	sip_pvt_lock(pkt->owner);

	if (!pkt->retrans_stop) {
		pkt->retrans++;
		if (!pkt->timer_t1) {	/* Re-schedule using timer_a and timer_t1 */
			if (sipdebug) {
				ast_debug(4, "SIP TIMER: Not rescheduling id #%d:%s (Method %d) (No timer T1)\n",
					pkt->retransid,
					sip_methods[pkt->method].text,
					pkt->method);
			}
		} else {
			int siptimer_a;

			if (sipdebug) {
				ast_debug(4, "SIP TIMER: Rescheduling retransmission #%d (%d) %s - %d\n",
					pkt->retransid,
					pkt->retrans,
					sip_methods[pkt->method].text,