From: W.C.A. Wijngaards <wouter@nlnetlabs.nl>
Date: Thu, 23 Jan 2020 10:07:30 +0000 (+0100)
Subject: dnstap io: check for close of channel by the other side.
X-Git-Tag: 1.11.0rc1~120^2~95
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=24536473d8871bdcc22b54049ada8380c1f54850;p=thirdparty%2Funbound.git

dnstap io: check for close of channel by the other side.
---

diff --git a/dnstap/dtstream.c b/dnstap/dtstream.c
index c3270a008..2642528ff 100644
--- a/dnstap/dtstream.c
+++ b/dnstap/dtstream.c
@@ -543,11 +543,56 @@ static int dtio_write_more(struct dt_io_thread* dtio)
 	return 1;
 }
 
+/** check if the output fd has been closed */
+static void dtio_check_close(struct dt_io_thread* dtio)
+{
+	/* we don't want to read any packets, but if there are we can
+	 * discard the input (ignore it), which is okay for a framestream,
+	 * and also, the read call can return that the stream has been
+	 * closed by the other side. */
+	ssize_t r;
+	uint8_t buf[1024];
+	if(dtio->fd == -1) return;
+	while(1) {
+		r = recv(dtio->fd, buf, sizeof(buf), 0);
+		if(r == -1) {
+#ifndef USE_WINSOCK
+			if(errno == EINTR || errno == EAGAIN)
+				return; /* try later */
+#else
+			if(WSAGetLastError() == WSAEINPROGRESS) {
+				return; /* try later */
+			} else if(WSAGetLastError() == WSAEWOULDBLOCK) {
+				ub_winsock_tcp_wouldblock(dtio->event, UB_EV_READ);
+				return; /* try later */
+			}
+#endif
+			log_err("dnstap io: output recv: %s", strerror(errno));
+			/* and close below */
+			break;
+		}
+		if(r == 0) {
+			verbose(VERB_ALGO, "dnstap io: output closed by the other side");
+			/* and close below */
+			break;
+		}
+		/* something was received, ignore it */
+	}
+	/* the other end has been closed */
+	/* close the channel */
+	dtio_del_output_event(dtio);
+	dtio_close_output(dtio);
+}
+
 /** callback for the dnstap events, to write to the output */
-static void dtio_output_cb(int ATTR_UNUSED(fd), short ATTR_UNUSED(bits),
-	void* arg)
+static void dtio_output_cb(int ATTR_UNUSED(fd), short bits, void* arg)
 {
 	struct dt_io_thread* dtio = (struct dt_io_thread*)arg;
+
+	if((bits&UB_EV_READ)) {
+		dtio_check_close(dtio);
+		return;
+	}
 	
 	/* see if there are messages that need writing */
 	if(!dtio->cur_msg) {
@@ -701,13 +746,21 @@ static void dtio_stop_timer_cb(int ATTR_UNUSED(fd), short ATTR_UNUSED(bits),
 	dtio_stop_flush_exit(info);
 }
 
-static void dtio_stop_ev_cb(int ATTR_UNUSED(fd), short ATTR_UNUSED(bits),
-	void* arg)
+static void dtio_stop_ev_cb(int ATTR_UNUSED(fd), short bits, void* arg)
 {
 	struct stop_flush_info* info = (struct stop_flush_info*)arg;
 	struct dt_io_thread* dtio = info->dtio;
 	if(info->want_to_exit_flush)
 		return;
+	if((bits&UB_EV_READ)) {
+		dtio_check_close(dtio);
+		if(dtio->fd == -1) {
+			verbose(VERB_ALGO, "dnstap io: "
+				"stop flush: output closed");
+			dtio_stop_flush_exit(info);
+		}
+		return;
+	}
 	/* write remainder of last frame */
 	if(dtio->cur_msg) {
 		if(dtio->cur_msg_done < dtio->cur_msg_len) {