From: Aron Xu <aron@debian.org>
Date: Mon, 13 Feb 2012 15:16:04 +0800
Subject: New flag '-q' to specify a quit timer

---
 nc.1     | 10 ++++++++++
 netcat.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 58 insertions(+), 11 deletions(-)

diff --git a/nc.1 b/nc.1
index 478fedd..fbcc098 100644
--- a/nc.1
+++ b/nc.1
@@ -41,6 +41,7 @@
 .Op Fl O Ar length
 .Op Fl P Ar proxy_username
 .Op Fl p Ar source_port
+.Op Fl q Ar seconds
 .Op Fl s Ar sourceaddr
 .Op Fl T Ar keyword
 .Op Fl V Ar rtable
@@ -167,6 +168,15 @@ Proxy authentication is only supported for HTTP CONNECT proxies at present.
 Specify the source port
 .Nm
 should use, subject to privilege restrictions and availability.
+.It Fl q Ar seconds
+after EOF on stdin, wait the specified number of
+.Ar seconds
+and then quit. If
+.Ar seconds
+is negative, wait forever (default).  Specifying a non-negative
+.Ar seconds
+implies
+.Fl N .
 .It Fl r
 Choose source and/or destination ports randomly
 instead of sequentially within a range or in the order that the system
diff --git a/netcat.c b/netcat.c
index 2f3e9a8..03d339c 100644
--- a/netcat.c
+++ b/netcat.c
@@ -139,6 +139,7 @@ int	Nflag;					/* shutdown() network socket */
 int	nflag;					/* Don't do name look up */
 char   *Pflag;					/* Proxy username */
 char   *pflag;					/* Localport flag */
+int    qflag = -1;				/* Quit after some secs */
 int	rflag;					/* Random ports flag */
 char   *sflag;					/* Source Address */
 int	tflag;					/* Telnet Emulation */
@@ -223,6 +224,7 @@ ssize_t fillbuf(int, unsigned char *, size_t *);
 #endif
 
 static int connect_with_timeout(int, const struct sockaddr *, socklen_t, int);
+static void quit(int sig);
 
 int
 main(int argc, char *argv[])
@@ -255,9 +257,9 @@ main(int argc, char *argv[])
 
 	while ((ch = getopt(argc, argv,
 #ifdef HAVE_TLS
-	    "46C:cDde:FH:hI:i:K:klM:m:NnO:o:P:p:R:rSs:T:tUuV:vW:w:X:x:Z:z"))
+	    "46C:cDde:FH:hI:i:K:klM:m:NnO:o:P:p:q:R:rSs:T:tUuV:vW:w:X:x:Z:z"))
 #else
-	    "46CDdFhI:i:klM:m:NnO:P:p:rSs:T:tUuV:vW:w:X:x:z"))
+	    "46CDdFhI:i:klM:m:NnO:P:p:q:rSs:T:tUuV:vW:w:X:x:z"))
 #endif
 	    != -1) {
 		switch (ch) {
@@ -349,6 +351,13 @@ main(int argc, char *argv[])
 		case 'p':
 			pflag = optarg;
 			break;
+		case 'q':
+			qflag = strtonum(optarg, INT_MIN, INT_MAX, &errstr);
+			if (errstr)
+				errx(1, "quit timer %s: %s", errstr, optarg);
+			if (qflag >= 0)
+				Nflag = 1;
+			break;
 #ifdef HAVE_TLS
 		case 'R':
 			tls_cachanged = 1;
@@ -1335,15 +1344,27 @@ readwrite(int net_fd)
 	while (1) {
 		/* both inputs are gone, buffers are empty, we are done */
 		if (pfd[POLL_STDIN].fd == -1 && pfd[POLL_NETIN].fd == -1 &&
-		    stdinbufpos == 0 && netinbufpos == 0)
-			return;
+		    stdinbufpos == 0 && netinbufpos == 0) {
+			if (qflag <= 0)
+				return;
+			goto delay_exit;
+		}
 		/* both outputs are gone, we can't continue */
-		if (pfd[POLL_NETOUT].fd == -1 && pfd[POLL_STDOUT].fd == -1)
-			return;
+		if (pfd[POLL_NETOUT].fd == -1 && pfd[POLL_STDOUT].fd == -1) {
+			if (qflag <= 0)
+				return;
+			goto delay_exit;
+		}
 		/* listen and net in gone, queues empty, done */
 		if (lflag && pfd[POLL_NETIN].fd == -1 &&
-		    stdinbufpos == 0 && netinbufpos == 0)
-			return;
+		    stdinbufpos == 0 && netinbufpos == 0) {
+			if (qflag <= 0)
+				return;
+delay_exit:
+			close(net_fd);
+			signal(SIGALRM, quit);
+			alarm(qflag);
+		}
 
 		/* poll */
 		num_fds = poll(pfd, 4, timeout);
@@ -1500,6 +1521,13 @@ readwrite(int net_fd)
 			if (pfd[POLL_NETOUT].fd != -1 && Nflag)
 				shutdown(pfd[POLL_NETOUT].fd, SHUT_WR);
 			pfd[POLL_NETOUT].fd = -1;
+			/* #817050: handle UDP sockets and kflag */
+			if ((lflag || uflag) && pfd[POLL_NETIN].fd != -1 &&
+			    qflag >= 0 && netinbufpos == 0) {
+				shutdown(pfd[POLL_NETIN].fd, SHUT_RD);
+				pfd[POLL_NETIN].fd = -1;
+				kflag = 0;
+			}
 		}
 		/* net in gone and queue empty? */
 		if (pfd[POLL_NETIN].fd == -1 && netinbufpos == 0) {
@@ -2106,6 +2134,7 @@ help(void)
 	\t-O length	TCP send buffer length\n\
 	\t-P proxyuser\tUsername for proxy authentication\n\
 	\t-p port\t	Specify local port for remote connects\n\
+	\t-q secs\t	quit after EOF on stdin and delay of secs\n\
 	\t-r		Randomize remote ports\n\
 	\t-S		Enable the TCP MD5 signature option\n\
 	\t-s sourceaddr	Local source address\n\
@@ -2130,10 +2159,18 @@ usage(int ret)
 	fprintf(stderr,
 	    "usage: nc [-46CDdFhklNnrStUuvz] [-I length] [-i interval] [-M ttl]\n"
 	    "\t  [-m minttl] [-O length] [-P proxy_username] [-p source_port]\n"
-	    "\t  [-s sourceaddr] [-T keyword] [-V rtable] [-W recvlimit] "
-	    "[-w timeout]\n"
-	    "\t  [-X proxy_protocol] [-x proxy_address[:port]]\n"
+	    "\t  [-q seconds] [-s sourceaddr] [-T keyword] [-V rtable] [-W recvlimit]\n"
+	    "\t  [-w timeout] [-X proxy_protocol] [-x proxy_address[:port]]\n"
 	    "\t  [destination] [port]\n");
 	if (ret)
 		exit(1);
 }
+
+/*
+ * quit()
+ * handler for a "-q" timeout (exit 0 instead of 1)
+ */
+static void quit(__attribute__((unused)) int sig)
+{
+	exit(0);
+}