X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=udp_send.c;h=24ebf5848ed3c2de5d671de98dab142ce9018581;hp=08429aa42601194df0304775fe853ea98eddcfe7;hb=4ebaf62d6bbd0498d93e19bc4f0a3c9564b1a8f5;hpb=0c395e45939ec272214ea14f3c07fc925a5697f5

diff --git a/udp_send.c b/udp_send.c
index 08429aa4..24ebf584 100644
--- a/udp_send.c
+++ b/udp_send.c
@@ -32,12 +32,21 @@
 #include "close_on_fork.h"
 #include "chunk_queue.h"
 
+/**
+ * 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 {
 	/** The hostname (DNS name or IPv4/v6 address string). */
 	char host[MAX_HOSTLEN];
 	/** The UDP port. */
 	int port;
+	/** 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(). */
@@ -219,6 +228,38 @@ static int udp_init_fec(struct sender_client *sc)
 	return mps;
 }
 
+/** Check and clear socket error if any. */
+static int udp_check_socket_state(struct udp_target *ut)
+{
+	int ret;
+	socklen_t errlen = sizeof(ret);
+
+	if (getsockopt(ut->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#%d after %d seconds "
+					"of connection errors.\n",
+					ut->host, ut->port, (int)dist);
+		}
+	}
+	return -ERRNO_TO_PARA_ERROR(ret);
+}
+
 static int udp_send_fec(struct sender_client *sc, char *buf, size_t len)
 {
 	struct udp_target *ut = sc->private_data;
@@ -226,21 +267,27 @@ static int udp_send_fec(struct sender_client *sc, char *buf, size_t len)
 
 	if (sender_status == SENDER_OFF)
 		return 0;
+	if (len == 0 && !cq_peek(ut->sc->cq))
+		return 0;
+	ret = udp_check_socket_state(ut);
+	if (ret < 0)
+		goto fail;
 	ret = send_queued_chunks(sc->fd, sc->cq);
-	if (ret == -ERRNO_TO_PARA_ERROR(ECONNREFUSED))
-		ret = 0;
 	if (ret < 0)
 		goto fail;
-	if (!len)
-		return 0;
 	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))
+	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) {