From 8d34651b6c76da47148db090fc1423cc222798e5 Mon Sep 17 00:00:00 2001
From: David Greenman <dg@FreeBSD.org>
Date: Wed, 3 May 1995 06:25:56 +0000
Subject: [PATCH] Added a "-D" option to set the TCP_NODELAY socket option.

---
 usr.bin/rlogin/rlogin.1 |  7 ++++++-
 usr.bin/rlogin/rlogin.c | 16 ++++++++++++----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/usr.bin/rlogin/rlogin.1 b/usr.bin/rlogin/rlogin.1
index 60da3cc07beb..8f4453a31be6 100644
--- a/usr.bin/rlogin/rlogin.1
+++ b/usr.bin/rlogin/rlogin.1
@@ -39,7 +39,7 @@
 .Nd remote login
 .Sh SYNOPSIS
 .Ar rlogin
-.Op Fl 8EKLdx
+.Op Fl 8DEKLdx
 .Op Fl e Ar char
 .Op Fl k Ar realm
 .Op Fl l Ar username
@@ -63,6 +63,11 @@ option allows an eight-bit input data path at all times; otherwise
 parity bits are stripped except when the remote side's stop and start
 characters are other than
 ^S/^Q .
+.It Fl D
+The
+.Fl D
+option sets the TCP_NODELAY socket option which can improve interactive response
+at the expense of increased network load.
 .It Fl E
 The
 .Fl E
diff --git a/usr.bin/rlogin/rlogin.c b/usr.bin/rlogin/rlogin.c
index d9379c2550ed..bdd60a311e5f 100644
--- a/usr.bin/rlogin/rlogin.c
+++ b/usr.bin/rlogin/rlogin.c
@@ -53,6 +53,7 @@ static char sccsid[] = "@(#)rlogin.c	8.1 (Berkeley) 6/6/93";
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
+#include <netinet/tcp.h>
 
 #include <errno.h>
 #include <fcntl.h>
@@ -150,10 +151,10 @@ main(argc, argv)
 	struct servent *sp;
 	struct sgttyb ttyb;
 	long omask;
-	int argoff, ch, dflag, one, uid;
+	int argoff, ch, dflag, Dflag, one, uid;
 	char *host, *p, *user, term[1024];
 
-	argoff = dflag = 0;
+	argoff = dflag = Dflag = 0;
 	one = 1;
 	host = user = NULL;
 
@@ -172,15 +173,18 @@ main(argc, argv)
 	}
 
 #ifdef KERBEROS
-#define	OPTIONS	"8EKLde:k:l:x"
+#define	OPTIONS	"8DEKLde:k:l:x"
 #else
-#define	OPTIONS	"8EKLde:l:"
+#define	OPTIONS	"8DEKLde:l:"
 #endif
 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != EOF)
 		switch(ch) {
 		case '8':
 			eight = 1;
 			break;
+		case 'D':
+			Dflag = 1;
+			break;
 		case 'E':
 			noescape = 1;
 			break;
@@ -337,6 +341,10 @@ try_connect:
 	    setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one, sizeof(one)) < 0)
 		(void)fprintf(stderr, "rlogin: setsockopt: %s.\n",
 		    strerror(errno));
+	if (Dflag &&
+	    setsockopt(rem, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)) < 0)
+		perror("rlogin: setsockopt NODELAY (ignored)");
+
 	one = IPTOS_LOWDELAY;
 	if (setsockopt(rem, IPPROTO_IP, IP_TOS, (char *)&one, sizeof(int)) < 0)
 		perror("rlogin: setsockopt TOS (ignored)");