From: Guy Harris <guy@alum.mit.edu>
Date: Sun, 1 Apr 2018 03:36:01 +0000 (-0700)
Subject: Don't log errors due to the peer dropping the connection.
X-Git-Tag: libpcap-1.9-bp~143
X-Git-Url: https://git.tcpdump.org/libpcap/commitdiff_plain/e750801220bf0e56852b319b2d5a4b2d342604d5

Don't log errors due to the peer dropping the connection.

They may happen because somebody ^C's a tcpdump; that's not worth
logging.

On UN*X, that might show up as ECONNRESET or EPIPE; on Windows, that
might show up as WSAECONNRESET or WSAECONNABORTED.
---

diff --git a/rpcapd/daemon.c b/rpcapd/daemon.c
index e2d89d96..54b259b8 100755
--- a/rpcapd/daemon.c
+++ b/rpcapd/daemon.c
@@ -2232,6 +2232,7 @@ daemon_thrdatamain(void *ptr)
 	size_t sendbufsize;			// size for the send buffer
 	char *sendbuf;						// temporary buffer in which data to be sent is buffered
 	int sendbufidx;						// index which keeps the number of bytes currently buffered
+	int status;
 
 	session = (struct session *) ptr;
 
@@ -2329,10 +2330,26 @@ daemon_thrdatamain(void *ptr)
 		}
 
 		// Send the packet
-		if (sock_send(session->sockdata, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE) == -1)
+		// If the client dropped the connection, don't report an
+		// error, just quit.
+		status = sock_send(session->sockdata, sendbuf, sendbufidx, errbuf, PCAP_ERRBUF_SIZE);
+		if (status < 0)
 		{
-			rpcapd_log(LOGPRIO_ERROR,
-			    "Send of packet to client failed: %s", errbuf);
+			if (status == -1)
+			{
+				//
+				// Error other than "client closed the
+				// connection out from under us"; report
+				// it.
+				//
+				rpcapd_log(LOGPRIO_ERROR,
+				    "Send of packet to client failed: %s",
+				    errbuf);
+			}
+
+			//
+			// Give up in either case.
+			//
 			goto error;
 		}
 	}
diff --git a/sockutils.c b/sockutils.c
index e7912fbe..2dfa9f90 100644
--- a/sockutils.c
+++ b/sockutils.c
@@ -640,7 +640,8 @@ int sock_initaddress(const char *host, const char *port,
  * larger than 'errbuflen - 1' because the last char is reserved for the string terminator.
  *
  * \return '0' if everything is fine, '-1' if an error other than
- * "connection reset" occurred, '-2' if "connection reset" occurred.
+ * "connection reset" or "peer has closed the receive side" occurred,
+ * '-2' if we got one of those errors.
  * For errors, an error message is returned in the 'errbuf' variable.
  */
 int sock_send(SOCKET sock, const char *buffer, size_t size,
@@ -686,15 +687,30 @@ int sock_send(SOCKET sock, const char *buffer, size_t size,
 
 #ifdef _WIN32
 			errcode = GetLastError();
-
-			sock_fmterror("send(): ", errcode, errbuf, errbuflen);
-			if (errcode == WSAECONNRESET)
+			if (errcode == WSAECONNRESET ||
+			    errcode == WSAECONNABORTED)
+			{
+				/*
+				 * WSAECONNABORTED appears to be the error
+				 * returned in Winsock when you try to send
+				 * on a connection where the peer has closed
+				 * the receive side.
+				 */
 				return -2;
+			}
+			sock_fmterror("send(): ", errcode, errbuf, errbuflen);
 #else
 			errcode = errno;
-			sock_fmterror("send(): ", errcode, errbuf, errbuflen);
-			if (errcode == ECONNRESET)
+			if (errcode == ECONNRESET || errcode == EPIPE)
+			{
+				/*
+				 * EPIPE is what's returned on UN*X when
+				 * you try to send on a connection when
+				 * the peer has closed the receive side.
+				 */
 				return -2;
+			}
+			sock_fmterror("send(): ", errcode, errbuf, errbuflen);
 #endif
 			return -1;
 		}