openwrtv4/package/busybox/patches/610-syslog-remote-retry-connection.patch

--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -555,6 +555,7 @@ static void do_syslogd(void)
 {
 	int sock_fd;
 #if ENABLE_FEATURE_REMOTE_LOG
+	int send_err = 0;
 	llist_t *item;
 #endif
 #if ENABLE_FEATURE_SYSLOGD_DUP
@@ -636,11 +637,23 @@ static void do_syslogd(void)
 				if (rh->remoteFD == -1)
 					continue;
 			}
-			/* Send message to remote logger, ignore possible error */
-			/* TODO: on some errors, close and set G.remoteFD to -1
-			 * so that DNS resolution and connect is retried? */
-			sendto(rh->remoteFD, recvbuf, sz+1, MSG_DONTWAIT,
-				&(rh->remoteAddr->u.sa), rh->remoteAddr->len);
+			/* Send message to remote logger */
+			if (sendto(rh->remoteFD, recvbuf, sz+1, MSG_DONTWAIT,
+				&(rh->remoteAddr->u.sa), rh->remoteAddr->len) == -1)
+				send_err = errno;
+
+			/* On some errors, close and set G.remoteFD to -1
+			 * so that DNS resolution and connect is retried */
+			switch (send_err) {
+				case ECONNRESET:
+				case EDESTADDRREQ:
+				case EISCONN:
+				case ENOTCONN:
+				case EPIPE:
+					close(rh->remoteFD);
+					rh->remoteFD = -1;
+					break;
+			}
 		}
 #endif
 		if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {