implement a `keep-alive' option that sends bytes over an inactive

connection. The FTP protocol provides us with a NOOP operation that
is perfectly suitable for that, and so far servers are happy with it.
Sending the command slowly is an idea I borrowed from spamd.
No change for people not using the option, so it can't break normal ftp.

okay beck@, jmc@

4 files changed, 114 insertions, 12 deletions

diff --git a/usr.bin/ftp/extern.h b/usr.bin/ftp/extern.h
index 864913387d6..8fefe122e5b 100644
--- a/usr.bin/ftp/extern.h
+++ b/usr.bin/ftp/extern.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: extern.h,v 1.30 2007/06/13 13:52:26 pyr Exp $	*/
+/*	$OpenBSD: extern.h,v 1.31 2007/06/16 08:58:33 espie Exp $	*/
 /*	$NetBSD: extern.h,v 1.17 1997/08/18 10:20:19 lukem Exp $	*/
 
 /*
@@ -208,6 +208,7 @@ extern int	proxy;
 extern char	reply_string[];
 extern off_t	restart_point;
 extern int	NCMDS;
+extern int	keep_alive_timeout;
 
 extern char *__progname;		/* from crt0.o */
 
diff --git a/usr.bin/ftp/ftp.1 b/usr.bin/ftp/ftp.1
index b6dfe8fae35..ffeae81112b 100644
--- a/usr.bin/ftp/ftp.1
+++ b/usr.bin/ftp/ftp.1
@@ -1,4 +1,4 @@
-.\" 	$OpenBSD: ftp.1,v 1.60 2007/06/13 18:43:16 jmc Exp $
+.\" 	$OpenBSD: ftp.1,v 1.61 2007/06/16 08:58:33 espie Exp $
 .\" 	$NetBSD: ftp.1,v 1.22 1997/08/18 10:20:22 lukem Exp $
 .\"
 .\" Copyright (c) 1985, 1989, 1990, 1993
@@ -30,7 +30,7 @@
 .\"
 .\"	@(#)ftp.1	8.3 (Berkeley) 10/9/94
 .\"
-.Dd $Mdocdate: June 13 2007 $
+.Dd $Mdocdate: June 16 2007 $
 .Dt FTP 1
 .Os
 .Sh NAME
@@ -40,6 +40,7 @@
 .Nm ftp
 .Op Fl 46AadEegimnptVv
 .Op Fl c Ar cookie
+.Op Fl k Ar seconds
 .Op Fl P Ar port
 .Op Fl r Ar seconds
 .Op Ar host Op Ar port
@@ -134,6 +135,19 @@ Disables file name globbing.
 .It Fl i
 Turns off interactive prompting during
 multiple file transfers.
+.It Fl k Ar seconds
+Sends a byte after each
+.Ar seconds
+period over the control connection during long transfers,
+so that incorrectly configured network equipment won't
+agressively drop it.
+The FTP protocol supports a
+.Dv NOOP
+command that can be used for that purpose.
+This assumes the FTP server can deal with extra commands coming over
+the control connection during a transfer.
+Well-behaved servers queue those commands, and process them after the
+transfer.
 .It Fl m
 Causes
 .Nm
diff --git a/usr.bin/ftp/ftp.c b/usr.bin/ftp/ftp.c
index 252b27585f2..3a9cf82bd69 100644
--- a/usr.bin/ftp/ftp.c
+++ b/usr.bin/ftp/ftp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ftp.c,v 1.66 2007/03/06 05:16:01 beck Exp $	*/
+/*	$OpenBSD: ftp.c,v 1.67 2007/06/16 08:58:33 espie Exp $	*/
 /*	$NetBSD: ftp.c,v 1.27 1997/08/18 10:20:23 lukem Exp $	*/
 
 /*
@@ -60,7 +60,7 @@
  */
 
 #if !defined(lint) && !defined(SMALL)
-static const char rcsid[] = "$OpenBSD: ftp.c,v 1.66 2007/03/06 05:16:01 beck Exp $";
+static const char rcsid[] = "$OpenBSD: ftp.c,v 1.67 2007/06/16 08:58:33 espie Exp $";
 #endif /* not lint and not SMALL */
 
 #include <sys/types.h>
@@ -325,6 +325,73 @@ command(const char *fmt, ...)
 	return (r);
 }
 
+int keep_alive_timeout = 0;		/* 0 -> no timeout */
+
+static int full_noops_sent = 0;
+static time_t last_timestamp = 0;	/* 0 -> no measurement yet */
+static char noop[] = "NOOP\r\n";
+#define NOOP_LENGTH (sizeof noop - 1)
+static int current_nop_pos = 0;		/* 0 -> no noop started */
+
+/* to achieve keep alive, we send noop one byte at a time */
+void 
+send_noop_char()
+{
+	if (debug)
+		fprintf(ttyout, "---> %c\n", noop[current_nop_pos]);
+	fputc(noop[current_nop_pos++], cout);
+	(void)fflush(cout);
+	if (current_nop_pos >= NOOP_LENGTH) {
+		full_noops_sent++;
+		current_nop_pos = 0;
+	}
+}
+
+void
+may_reset_noop_timeout()
+{
+	if (keep_alive_timeout != 0)
+		last_timestamp = time(NULL);
+}
+
+void 
+may_receive_noop_ack()
+{
+	int i;
+
+	/* finish sending last incomplete noop */
+	if (current_nop_pos != 0) {
+		fputs(&(noop[current_nop_pos]), cout);
+		if (debug)
+			fprintf(ttyout, "---> %s\n", &(noop[current_nop_pos]));
+		(void)fflush(cout);
+		current_nop_pos = 0;
+		full_noops_sent++;
+	}
+	/* and get the replies */
+	for (i = 0; i < full_noops_sent; i++)
+		(void)getreply(0);
+
+	full_noops_sent = 0;
+}
+
+void 
+may_send_noop_char()
+{
+	if (keep_alive_timeout != 0) {
+		if (last_timestamp != 0) {
+			time_t t = time(NULL);
+
+			if (t - last_timestamp >= keep_alive_timeout) {
+				last_timestamp = t;
+				send_noop_char();
+			} 
+		} else {
+			last_timestamp = time(NULL);
+		}
+	}
+}
+
 char reply_string[BUFSIZ];		/* first line of previous reply */
 
 int
@@ -631,6 +698,7 @@ sendrequest(const char *cmd, const char *local, const char *remote,
 	if (dout == NULL)
 		goto abort;
 	progressmeter(-1);
+	may_reset_noop_timeout();
 	oldintp = signal(SIGPIPE, SIG_IGN);
 	switch (curtype) {
 
@@ -638,6 +706,7 @@ sendrequest(const char *cmd, const char *local, const char *remote,
 	case TYPE_L:
 		errno = d = 0;
 		while ((c = read(fileno(fin), buf, sizeof(buf))) > 0) {
+			may_send_noop_char();
 			bytes += c;
 			for (bufp = buf; c > 0; c -= d, bufp += d)
 				if ((d = write(fileno(dout), bufp, (size_t)c))
@@ -668,6 +737,7 @@ sendrequest(const char *cmd, const char *local, const char *remote,
 
 	case TYPE_A:
 		while ((c = fgetc(fin)) != EOF) {
+			may_send_noop_char();
 			if (c == '\n') {
 				while (hash && (!progress || filesize < 0) &&
 				    (bytes >= hashbytes)) {
@@ -710,6 +780,7 @@ sendrequest(const char *cmd, const char *local, const char *remote,
 		(*closefunc)(fin);
 	(void)fclose(dout);
 	(void)getreply(0);
+	may_receive_noop_ack();
 	(void)signal(SIGINT, oldintr);
 	(void)signal(SIGINFO, oldinti);
 	if (oldintp)
@@ -938,6 +1009,7 @@ recvrequest(const char *cmd, const char * volatile local, const char *remote,
 		preserve = 0;
 	}
 	progressmeter(-1);
+	may_reset_noop_timeout();
 	switch (curtype) {
 
 	case TYPE_I:
@@ -956,6 +1028,7 @@ recvrequest(const char *cmd, const char * volatile local, const char *remote,
 			ssize_t	wr;
 			size_t	rd = c;
 
+			may_send_noop_char();
 			d = 0;
 			do {
 				wr = write(fileno(fout), buf + d, rd);
@@ -1018,6 +1091,7 @@ done:
 			}
 		}
 		while ((c = fgetc(din)) != EOF) {
+			may_send_noop_char();
 			if (c == '\n')
 				bare_lfs++;
 			while (c == '\r') {
@@ -1077,6 +1151,7 @@ break2:
 		(void)signal(SIGPIPE, oldintp);
 	(void)fclose(din);
 	(void)getreply(0);
+	may_receive_noop_ack();
 	if (bytes >= 0 && is_retr) {
 		if (bytes > 0)
 			ptransfer(0);
diff --git a/usr.bin/ftp/main.c b/usr.bin/ftp/main.c
index 43ce223e1a9..c83ad2440c2 100644
--- a/usr.bin/ftp/main.c
+++ b/usr.bin/ftp/main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: main.c,v 1.64 2007/06/13 18:43:16 jmc Exp $	*/
+/*	$OpenBSD: main.c,v 1.65 2007/06/16 08:58:33 espie Exp $	*/
 /*	$NetBSD: main.c,v 1.24 1997/08/18 10:20:26 lukem Exp $	*/
 
 /*
@@ -66,7 +66,7 @@ static const char copyright[] =
 #endif /* not lint */
 
 #if !defined(lint) && !defined(SMALL)
-static const char rcsid[] = "$OpenBSD: main.c,v 1.64 2007/06/13 18:43:16 jmc Exp $";
+static const char rcsid[] = "$OpenBSD: main.c,v 1.65 2007/06/16 08:58:33 espie Exp $";
 #endif /* not lint and not SMALL */
 
 /*
@@ -181,7 +181,7 @@ main(volatile int argc, char *argv[])
 	cookiefile = getenv("http_cookies");
 #endif
 
-	while ((ch = getopt(argc, argv, "46Aac:dEegimno:pP:r:tvV")) != -1) {
+	while ((ch = getopt(argc, argv, "46Aac:dEegik:mno:pP:r:tvV")) != -1) {
 		switch (ch) {
 		case '4':
 			family = PF_INET;
@@ -227,6 +227,15 @@ main(volatile int argc, char *argv[])
 			interactive = 0;
 			break;
 
+		case 'k':
+			keep_alive_timeout = strtonum(optarg, 0, INT_MAX, 
+			    &errstr);
+			if (errstr != NULL) {
+				warnx("keep alive amount is %s: %s", errstr, 
+					optarg);
+				usage();
+			}
+			break;
 		case 'm':
 			progress = -1;
 			break;
@@ -252,9 +261,11 @@ main(volatile int argc, char *argv[])
 
 		case 'r':
 			retry_connect = strtonum(optarg, 0, INT_MAX, &errstr);
-			if (errstr != NULL)
-				errx(1, "retry amount is %s: %s", errstr, 
+			if (errstr != NULL) {
+				warnx("retry amount is %s: %s", errstr, 
 					optarg);
+				usage();
+			}
 			break;
 
 		case 't':
@@ -746,8 +757,9 @@ void
 usage(void)
 {
 	(void)fprintf(stderr,
-	    "usage: %s [-46AadEegimnptVv] [-c cookie] [-P port] "
-	    "[-r seconds] [host [port]]\n"
+	    "usage: %s [-46AadEegimnptVv] [-c cookie] [-k seconds] "
+	    "[-P port] [-r seconds]\n"
+	    "           [host [port]]\n"
 	    "       %s [-o output] ftp://[user:password@]host[:port]/file[/]\n"
 	    "       %s [-o output] http://host[:port]/file\n"
 #ifndef SMALL