X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=udp_send.c;h=adf233979c31e2aff79ecdf94b5b16fd6f8765da;hp=140458e7ed9b1d4e3a03d05c2e26a6b36d66db54;hb=6b935f552ebfe3a0a83ec9367deb2f42c1aff252;hpb=1e6a73e98fecaba8226d5a4aa3cdc84e410f8029

diff --git a/udp_send.c b/udp_send.c
index 140458e7..adf23397 100644
--- a/udp_send.c
+++ b/udp_send.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2005-2010 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -7,8 +7,13 @@
 /** \file udp_send.c Para_server's udp sender. */
 
 
+#include <regex.h>
 #include <sys/time.h>
 #include <dirent.h>
+#include <sys/socket.h>
+#include <netinet/udp.h>
+#include <net/if.h>
+#include <osl.h>
 
 #include "server.cmdline.h"
 #include "para.h"
@@ -17,80 +22,86 @@
 #include "afh.h"
 #include "afs.h"
 #include "server.h"
-#include "vss.h"
 #include "list.h"
 #include "send.h"
+#include "vss.h"
 #include "portable_io.h"
-#include "udp_header.h"
 #include "net.h"
 #include "fd.h"
 #include "sched.h"
 #include "close_on_fork.h"
 #include "chunk_queue.h"
 
-/** Convert in_addr to ascii. */
-#define TARGET_ADDR(oc) inet_ntoa((oc)->addr)
+/**
+ * Time window during which ICMP Destination/Port Unreachable messages are
+ * ignored, covering transient receiver problems such as restarting the
+ * client, rebooting, reconfiguration, or handover.
+ */
+#define UDP_MAX_UNREACHABLE_TIME 30
 
 /** Describes one entry in the list of targets for the udp sender. */
 struct udp_target {
-	/** Address info. */
-	struct in_addr addr;
-	/** The position of this target in the list of targets. */
-	struct list_head node;
-	/** The UDP port. */
-	int port;
-	/** The socket fd. */
-	int fd;
-	/** The list of queued chunks for this fd. */
-	struct chunk_queue *cq;
+	/** Track time (seconds) of last ICMP Port Unreachable error */
+	time_t last_unreachable;
+	/** Common sender client data */
+	struct sender_client *sc;
+	/** The opaque structure returned by vss_add_fec_client(). */
+	struct fec_client *fc;
+	/** The FEC parameters for this target. */
+	struct fec_client_parms fcp;
 };
 
 static struct list_head targets;
 static int sender_status;
 
-static void udp_close_target(struct udp_target *ut)
+static void udp_close_target(struct sender_client *sc)
 {
-	if (ut->fd < 0)
-		return;
-	close(ut->fd);
-	del_close_on_fork_list(ut->fd);
-	cq_destroy(ut->cq);
-	ut->cq = NULL;
-	ut->fd = -1;
+	if (sc->cq != NULL) {
+		del_close_on_fork_list(sc->fd);
+		cq_destroy(sc->cq);
+		sc->cq = NULL;
+	}
 }
 
-static void udp_delete_target(struct udp_target *ut, const char *msg)
+static void udp_delete_target(struct sender_client *sc, const char *msg)
 {
-	PARA_NOTICE_LOG("deleting %s:%d (%s) from list\n", TARGET_ADDR(ut),
-		ut->port, msg);
-	udp_close_target(ut);
-	list_del(&ut->node);
+	struct udp_target *ut = sc->private_data;
+
+	PARA_NOTICE_LOG("deleting %s (%s) from list\n", sc->name, msg);
+	udp_close_target(sc);
+	vss_del_fec_client(ut->fc);
+	list_del(&sc->node);
+	free(sc->name);
+	free(sc);
 	free(ut);
 }
 
 /**
  * Perform AF-independent multicast sender setup.
  *
- * \param fd	The connected socket descriptor.
- * \param ttl	UDPv4 multicast TTL or UDPv6 multicast number of hops.
- *		Use -1 to mean default, 0..255 otherwise.
- * \param iface	The outgoing multicast interface, or NULL for the default.
+ * \param sc	The connected sender client.
  *
  * \return Zero if okay, negative on error.
  */
-static int mcast_sender_setup(struct udp_target *ut, int ttl, char *iface)
+static int mcast_sender_setup(struct sender_client *sc)
 {
 	struct sockaddr_storage ss;
 	socklen_t sslen = sizeof(ss);
-
+	int ttl = conf.udp_ttl_arg, id = 0;
 	const int on = 1;
-	int id = iface == NULL ? 0 : if_nametoindex(iface);
 
-	if (getpeername(ut->fd, (struct sockaddr *)&ss, &sslen) < 0)
-		goto err;
+	if (conf.udp_mcast_iface_given) {
+		char *iface = conf.udp_mcast_iface_arg;
 
-	if (iface != NULL && id == 0)
-		PARA_WARNING_LOG("could not resolve interface %s, using default", iface);
+		id = if_nametoindex(iface);
+		if (id == 0)
+			PARA_WARNING_LOG("could not resolve interface '%s', "
+					"using default", iface);
+	}
+
+	if (getpeername(sc->fd, (struct sockaddr *)&ss, &sslen) < 0)
+		goto err;
+	assert(ss.ss_family == AF_INET || ss.ss_family == AF_INET6);
 
 	/* RFC 3493, 5.2: -1 means 'use kernel default' */
 	if (ttl < 0 || ttl > 255)
@@ -106,7 +117,7 @@ static int mcast_sender_setup(struct udp_target *ut, int ttl, char *iface)
 
 			memset(&mn, 0, sizeof(mn));
 			mn.imr_ifindex = id;
-			if (setsockopt(ut->fd, IPPROTO_IP, IP_MULTICAST_IF, &mn, sizeof(mn)) < 0)
+			if (setsockopt(sc->fd, IPPROTO_IP, IP_MULTICAST_IF, &mn, sizeof(mn)) < 0)
 				goto err;
 #else
 			PARA_ERROR_LOG("No support for setting outgoing IPv4 mcast interface.");
@@ -116,29 +127,26 @@ static int mcast_sender_setup(struct udp_target *ut, int ttl, char *iface)
 		 * Enable receiving multicast messages generated on the local host
 		 * At least on Linux, this is enabled by default.
 		 */
-		if (setsockopt(ut->fd, IPPROTO_IP, IP_MULTICAST_LOOP, &on, sizeof(on)) < 0)
+		if (setsockopt(sc->fd, IPPROTO_IP, IP_MULTICAST_LOOP, &on, sizeof(on)) < 0)
 			break;
 
 		/* Default: use local subnet (do not flood out into the WAN) */
 		if (ttl == -1)
 			ttl = 1;
-		if (setsockopt(ut->fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
+		if (setsockopt(sc->fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 			break;
 		return 0;
 	case AF_INET6:
 		if (!IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6 *)&ss)->sin6_addr))
 			return 0;
 		if (id != 0 &&
-		    setsockopt(ut->fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &id, sizeof(id)) < 0)
+		    setsockopt(sc->fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &id, sizeof(id)) < 0)
 			break;
-		if (setsockopt(ut->fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &on, sizeof(on)) < 0)
+		if (setsockopt(sc->fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &on, sizeof(on)) < 0)
 			break;
-		if (setsockopt(ut->fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0)
+		if (setsockopt(sc->fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 			break;
 		return 0;
-	default:
-		PARA_ERROR_LOG("address family %d not supported", ss.ss_family);
-		return -E_ADDRESS_LOOKUP;
 	}
 err:
 	return -ERRNO_TO_PARA_ERROR(errno);
@@ -147,148 +155,49 @@ err:
 /** The maximal size of the per-target chunk queue. */
 #define UDP_CQ_BYTES 40000
 
-static int udp_init_session(struct udp_target *ut)
+static void udp_init_session(struct sender_client *sc)
 {
-	int ret;
-	char *iface = NULL;
-
-	if (ut->fd >= 0) /* nothing to do */
-		return 0;
-
-	ret = makesock(AF_UNSPEC, IPPROTO_UDP, 0, TARGET_ADDR(ut), ut->port);
-	if (ret < 0)
-		return ret;
-	ut->fd = ret;
-
-	if (conf.udp_mcast_iface_given)
-		iface = conf.udp_mcast_iface_arg;
-
-	ret = mcast_sender_setup(ut, conf.udp_ttl_arg, iface);
-	if (ret < 0) {
-		close(ut->fd);
-		return ret;
-	}
-
-	ret = mark_fd_nonblocking(ut->fd);
-	if (ret < 0) {
-		close(ut->fd);
-		return ret;
+	if (sc->cq == NULL) {
+		sc->cq = cq_new(UDP_CQ_BYTES);
+		add_close_on_fork_list(sc->fd);
+		PARA_NOTICE_LOG("sending to udp %s\n", sc->name);
 	}
-	add_close_on_fork_list(ut->fd);
-	ut->cq = cq_new(UDP_CQ_BYTES);
-	PARA_NOTICE_LOG("sending to udp %s:%d\n", TARGET_ADDR(ut), ut->port);
-	return 1;
 }
 
-static void udp_send_buf(char *buf, size_t len)
+static void udp_shutdown_targets(void)
 {
-	struct udp_target *ut, *tmp;
-	int ret;
-
-	list_for_each_entry_safe(ut, tmp, &targets, node) {
-		ret = udp_init_session(ut);
-		if (ret < 0) {
-			udp_delete_target(ut, para_strerror(-ret));
-			continue;
+	struct sender_client *sc, *tmp;
+	const char *buf;
+	size_t len = vss_get_fec_eof_packet(&buf);
+
+	list_for_each_entry_safe(sc, tmp, &targets, node)
+		if (sc->cq != NULL) {
+			/* ignore return value, closing the target anyway. */
+			(void)write(sc->fd, buf, len);
+			udp_close_target(sc);
 		}
-		ret = send_queued_chunks(ut->fd, ut->cq, 0);
-		if (ret < 0) {
-			udp_delete_target(ut, para_strerror(-ret));
-			continue;
-		}
-		if (!len)
-			continue;
-		if (!ret) { /* still data left in the queue */
-			ret = cq_enqueue(ut->cq, buf, len);
-			if (ret < 0) {
-				udp_delete_target(ut, para_strerror(-ret));
-				continue;
-			}
-		}
-		ret = write_nonblock(ut->fd, buf, len, 0);
-		if (ret < 0) {
-			udp_delete_target(ut, para_strerror(-ret));
-			continue;
-		}
-		if (ret != len) {
-			ret = cq_enqueue(ut->cq, buf + ret, len - ret);
-			if (ret < 0) {
-				udp_delete_target(ut, para_strerror(-ret));
-				continue;
-			}
-		}
-	}
 }
 
-static void udp_shutdown_targets(void)
+static int udp_resolve_target(const char *url, struct sender_command_data *scd)
 {
-	char buf[UDP_AUDIO_HEADER_LEN];
-	struct udp_target *ut, *tmp;
-	struct udp_audio_header uah = {
-		.stream_type = UDP_UNKNOWN_STREAM,
-		.packet_type = UDP_EOF_PACKET,
-	};
-
-	write_udp_audio_header(buf, &uah);
-	list_for_each_entry_safe(ut, tmp, &targets, node) {
-		if (ut->fd < 0)
-			continue;
-		write(ut->fd, buf, UDP_AUDIO_HEADER_LEN);
-		udp_close_target(ut);
-	}
-}
+	const char *result;
+	int ret, port;
 
-static int need_extra_header(long unsigned current_chunk)
-{
-	static struct timeval last_header;
-	struct timeval diff;
+	ret = parse_fec_url(url, scd);
+	if (ret)
+		return ret;
+	port = scd->port > 0 ? scd->port : conf.udp_default_port_arg;
 
-	if (!current_chunk)
-		return 0;
-	tv_diff(now, &last_header, &diff);
-	if (tv2ms(&diff) < conf.udp_header_interval_arg)
-		return 0;
-	last_header = *now;
-	return 1;
-}
+	ret = para_connect_simple(IPPROTO_UDP, scd->host, port);
+	if (ret < 0)
+		return ret;
 
-static void udp_send(long unsigned current_chunk, __a_unused long unsigned chunks_sent,
-		const char *buf, size_t len, const char *header_buf,
-		size_t header_len)
-{
-	char *sendbuf;
-	size_t sendbuf_len;
-	struct timeval *chunk_tv;
-	struct udp_audio_header uah;
-
-//	PARA_NOTICE_LOG("len: %zd, header_len: %zd\n", len, header_len);
-	if (sender_status != SENDER_ON)
-		return;
-
-	/* we might not yet know the chunk time */
-	chunk_tv = vss_chunk_time();
-	if (!chunk_tv)
-		return;
-	if (list_empty(&targets))
-		return;
-	uah.stream_type = header_len? UDP_HEADER_STREAM : UDP_PLAIN_STREAM;
-	uah.header_len = need_extra_header(current_chunk)? header_len : 0;
-	if (!current_chunk)
-		uah.packet_type = UDP_BOF_PACKET;
-	else if (uah.header_len)
-		uah.packet_type = UDP_HEADER_PACKET;
-	else
-		uah.packet_type = UDP_DATA_PACKET;
-	uah.payload_len = uah.header_len + len;
-	sendbuf_len = UDP_AUDIO_HEADER_LEN + uah.payload_len;
-	sendbuf = para_malloc(sendbuf_len);
-	write_udp_audio_header(sendbuf, &uah);
-	if (uah.header_len)
-		memcpy(sendbuf + UDP_AUDIO_HEADER_LEN, header_buf,
-			uah.header_len);
-	memcpy(sendbuf + UDP_AUDIO_HEADER_LEN + uah.header_len, buf, len);
-	udp_send_buf(sendbuf, sendbuf_len);
-	free(sendbuf);
+	result = remote_name(ret);
+	close(ret);
+
+	if (!parse_url(result, scd->host, sizeof(scd->host), &scd->port))
+		return -E_ADDRESS_LOOKUP;
+	return 1;
 }
 
 static int udp_com_on(__a_unused struct sender_command_data *scd)
@@ -304,56 +213,190 @@ static int udp_com_off(__a_unused struct sender_command_data *scd)
 	return 1;
 }
 
-static int udp_com_delete(struct sender_command_data *scd)
+static struct sender_client *udp_lookup_target(struct sender_command_data *scd)
 {
-	char *a = para_strdup(inet_ntoa(scd->addr));
-	struct udp_target *ut, *tmp;
-	list_for_each_entry_safe(ut, tmp, &targets, node) {
-		if (scd->port != ut->port)
+	struct sender_client *sc, *tmp;
+	char host[MAX_HOSTLEN];
+	int32_t port;
+
+	list_for_each_entry_safe(sc, tmp, &targets, node) {
+		parse_url(sc->name, host, sizeof(host), &port);
+
+		/* Unspecified port means wildcard port match */
+		if (scd->port > 0 && scd->port != port)
 			continue;
-		if (strcmp(TARGET_ADDR(ut), a))
+		if (strcmp(host, scd->host))
 			continue;
-		udp_delete_target(ut, "com_delete");
+		return sc;
 	}
-	return 1;
+	return NULL;
+}
+
+static int udp_com_delete(struct sender_command_data *scd)
+{
+	struct sender_client *sc = udp_lookup_target(scd);
+
+	if (sc) {
+		udp_delete_target(sc, "com_delete");
+		return 1;
+	}
+	PARA_NOTICE_LOG("not deleting non-existing target '%s'\n", scd->host);
+	return -E_TARGET_NOT_FOUND;
 }
 
-static void udp_add_target(int port, struct in_addr *addr)
+/** Initialize UDP session and set maximum payload size. */
+static int udp_init_fec(struct sender_client *sc)
 {
-	struct udp_target *ut = para_calloc(sizeof(struct udp_target));
-	ut->port = port;
-	ut->addr = *addr;
-	ut->fd = -1; /* not yet connected */
-	PARA_INFO_LOG("adding to target list (%s:%d)\n",
-		TARGET_ADDR(ut), ut->port);
-	para_list_add(&ut->node, &targets);
+	int mps;
+
+	udp_init_session(sc);
+	mps = generic_max_transport_msg_size(sc->fd) - sizeof(struct udphdr);
+	PARA_INFO_LOG("current MPS = %d bytes\n", mps);
+	return mps;
+}
+
+/** Check and clear socket error if any. */
+static int udp_check_socket_state(struct sender_client *sc)
+{
+	struct udp_target *ut = sc->private_data;
+	int ret;
+	socklen_t errlen = sizeof(ret);
+
+	if (getsockopt(sc->fd, SOL_SOCKET, SO_ERROR, &ret, &errlen) < 0) {
+		PARA_ERROR_LOG("SO_ERROR failed: %s\n", strerror(ret));
+		return 0;
+	} else if (ret == 0) {
+		return 0;
+	} else if (ret == ECONNREFUSED) {
+		time_t dist = now->tv_sec - ut->last_unreachable;
+
+		if (dist <= UDP_MAX_UNREACHABLE_TIME) {
+			return 0;
+		} else if (dist > 2 * UDP_MAX_UNREACHABLE_TIME) {
+			ut->last_unreachable = now->tv_sec;
+			return 0;
+		} else {
+			/*
+			 * unreachable_time < dist <= 2 * unreachable_time
+			 * No errors are allowed during this time window.
+			 */
+			PARA_NOTICE_LOG("Evicting %s after %d seconds "
+					"of connection errors.\n",
+					sc->name, (int)dist);
+		}
+	}
+	return -ERRNO_TO_PARA_ERROR(ret);
+}
+
+static int udp_send_fec(struct sender_client *sc, char *buf, size_t len)
+{
+	int ret;
+
+	if (sender_status == SENDER_OFF)
+		return 0;
+	if (len == 0 && !cq_peek(sc->cq))
+		return 0;
+	ret = udp_check_socket_state(sc);
+	if (ret < 0)
+		goto fail;
+	ret = send_queued_chunks(sc->fd, sc->cq);
+	if (ret < 0)
+		goto fail;
+	if (!ret) { /* still data left in the queue */
+		ret = cq_force_enqueue(sc->cq, buf, len);
+		assert(ret >= 0);
+		return 0;
+	}
+	ret = write_nonblock(sc->fd, buf, len);
+	if (ret == -ERRNO_TO_PARA_ERROR(ECONNREFUSED)) {
+		/*
+		 * Happens if meanwhile an ICMP Destination / Port Unreachable
+		 * has arrived. Ignore, persistent errors will be caught above.
+		 */
+		ret = 0;
+	}
+	if (ret < 0)
+		goto fail;
+	if (ret != len) {
+		ret = cq_force_enqueue(sc->cq, buf + ret, len - ret);
+		assert(ret >= 0);
+	}
+	return 1;
+fail:
+	udp_delete_target(sc, para_strerror(-ret));
+	return ret;
 }
 
 static int udp_com_add(struct sender_command_data *scd)
 {
-	int port = (scd->port > 0)? scd->port : conf.udp_default_port_arg;
-	udp_add_target(port, &scd->addr);
+	int ret;
+	struct udp_target *ut;
+	struct sender_client *sc = udp_lookup_target(scd);
+
+	if (sc) {
+		PARA_NOTICE_LOG("target %s already exists - not adding it\n",
+				sc->name);
+		return -E_TARGET_EXISTS;
+	}
+	ut = para_calloc(sizeof(*ut));
+	sc = ut->sc = para_calloc(sizeof(*sc));
+	ut->fcp.slices_per_group      = scd->slices_per_group;
+	ut->fcp.data_slices_per_group = scd->data_slices_per_group;
+	ut->fcp.max_slice_bytes	      = scd->max_slice_bytes;
+	ut->fcp.init_fec	      = udp_init_fec;
+	ut->fcp.send_fec	      = udp_send_fec;
+
+	sc->private_data = ut;
+	sc->fd = -1;
+	ret = para_connect_simple(IPPROTO_UDP, scd->host, scd->port);
+	if (ret < 0)
+		goto err;
+	sc->fd = ret;
+
+	ret = mcast_sender_setup(sc);
+	if (ret < 0)
+		goto err;
+	ret = mark_fd_nonblocking(sc->fd);
+	if (ret < 0)
+		goto err;
+	sc->name = para_strdup(remote_name(sc->fd));
+	PARA_INFO_LOG("adding to target list (%s)\n", sc->name);
+	ut->fc = vss_add_fec_client(sc, &ut->fcp);
+	para_list_add(&sc->node, &targets);
 	return 1;
+err:
+	if (sc->fd >= 0)
+		close(sc->fd);
+	PARA_NOTICE_LOG("failed to set up %s:%d (%s)- not adding it\n",
+			scd->host, scd->port, para_strerror(-ret));
+	free(sc);
+	free(ut);
+	return ret;
 }
 
 static char *udp_info(void)
 {
-	struct udp_target *ut;
+	struct sender_client *sc;
 	char *ret, *tgts = NULL;
 
-	list_for_each_entry(ut, &targets, node) {
-		char *tmp = make_message("%s%s:%d ", tgts? tgts : "",
-			TARGET_ADDR(ut), ut->port);
+	list_for_each_entry(sc, &targets, node) {
+		struct udp_target *ut = sc->private_data;
+		char *tmp = make_message("%s%s/%u:%u:%u ",
+			tgts ? : "", sc->name,
+			ut->fcp.max_slice_bytes,
+			ut->fcp.data_slices_per_group,
+			ut->fcp.slices_per_group
+		);
 		free(tgts);
 		tgts = tmp;
 	}
 	ret = make_message(
 		"udp sender:\n"
 		"\tstatus: %s\n"
-		"\tport: udp %d\n"
+		"\tport: %s\n"
 		"\ttargets: %s\n",
 		(sender_status == SENDER_ON)? "on" : "off",
-		conf.udp_default_port_arg,
+		stringify_port(conf.udp_default_port_arg, "udp"),
 		tgts? tgts : "(none)"
 	);
 	free(tgts);
@@ -362,31 +405,16 @@ static char *udp_info(void)
 
 static void udp_init_target_list(void)
 {
+	struct sender_command_data scd;
 	int i;
 
 	INIT_LIST_HEAD(&targets);
 	for (i = 0; i < conf.udp_target_given; i++) {
-		char *arg = para_strdup(conf.udp_target_arg[i]);
-		char *p = strchr(arg, ':');
-		int port;
-		struct in_addr addr;
-
-		if (!p)
-			goto err;
-		*p = '\0';
-		if (!inet_pton(AF_INET, arg, &addr))
-			goto err;
-		port = atoi(++p);
-		if (port < 0 || port > 65535)
-			port = conf.udp_default_port_arg;
-		udp_add_target(port, &addr);
-		goto success;
-err:
-		PARA_CRIT_LOG("syntax error for udp target option "
-			"#%d, ignoring\n", i);
-success:
-		free(arg);
-		continue;
+		if (udp_resolve_target(conf.udp_target_arg[i], &scd) < 0)
+			PARA_CRIT_LOG("not adding requested target '%s'\n",
+					conf.udp_target_arg[i]);
+		else
+			udp_com_add(&scd);
 	}
 }
 
@@ -394,15 +422,25 @@ static char *udp_help(void)
 {
 	return make_message(
 		"usage: {on|off}\n"
-		"usage: {add|delete} IP port\n"
-		"example: add 224.0.1.38 8000 (multicast streaming)\n"
+		"usage: {add|delete} ip_address[:port][/[packet_size:]k:n]\n"
+		"       - k is the number of data slices per FEC group\n"
+		"       - n is the total number of slices in a FEC group\n"
+		"       - packet_size reduces the slice size below path MTU\n\n"
+		"examples: add 224.0.1.38:1500  (IPv4 multicast)\n"
+		"          add 224.0.1.38:8080/14:16 (explicit FEC)\n"
+		"          add 10.10.1.42       (using default port)\n"
+		"          add [FF05::42]:1500  (IPv6 multicast)\n"
+		"          add [::1]            (IPv6 localhost/default port)\n"
+		"          delete myhost.net    (host with port wildcard)\n"
+		"          delete 10.1.2.3:456  (IPv4 with explicit port)\n"
+		"          delete [badc0de::1]  (IPv6 with port wildcard)\n"
 	);
 }
 
 /**
  * The init function of para_server's udp sender.
  *
- * \param s Pointer to the http sender struct.
+ * \param s Pointer to the udp sender struct.
  *
  * It initializes all function pointers of \a s and the list of udp targets.
  */
@@ -411,10 +449,11 @@ void udp_send_init(struct sender *s)
 	INIT_LIST_HEAD(&targets);
 	s->info = udp_info;
 	s->help = udp_help;
-	s->send = udp_send;
+	s->send = NULL;
 	s->pre_select = NULL;
 	s->post_select = NULL;
 	s->shutdown_clients = udp_shutdown_targets;
+	s->resolve_target = udp_resolve_target;
 	s->client_cmds[SENDER_ON] = udp_com_on;
 	s->client_cmds[SENDER_OFF] = udp_com_off;
 	s->client_cmds[SENDER_DENY] = NULL;