Added support for the slip.hosts options 'normal', 'compress', 'noicmp',

and 'autocmp'.

Obtained from: (mostly) slattach and (slightly) 1.X

share/examples/sliplogin/slip.hosts

@@ -1,11 +1,13 @@
 #	@(#)slip.hosts	8.1 (Berkeley) 6/6/93
 #
-# login		local-addr	remote-addr	mask		opt1	opt2
-#						(normal,compress,noicmp)
+# login		local-addr	remote-addr	mask		option(s)
 #
+# option(s) consist of the following: (see the sliplogin man page)
+#   (normal,compress,noicmp,autocomp)
+# 
 Schez		vangogh		chez		0xffffff00	compress
 Sjun		vangogh		128.32.130.36	0xffffff00	normal
 Sleconte	vangogh		leconte		0xffffff00	compress
 Sleeb		vangogh		leeb		0xffffff00	compress
-Smjk		vangogh		pissaro-sl	0xffffff00	compress
-Soxford		vangogh		oxford		0xffffff00	compress
+Smjk		vangogh		pissaro-sl	0xffffff00	noicmp
+Soxford		vangogh		oxford		0xffffff00	autocomp

usr.sbin/sliplogin/sliplogin.8

@@ -55,14 +55,30 @@ for an entry matching
 If a matching entry is found, the line is configured appropriately
 for slip (8-bit transparent i/o) and converted to
 .Tn SLIP
-line
-discipline.
+line discipline using the optional line discipline parameters.
+.Pp
+The optional line discipline parameters consist of one or more of
+the following;
+.Sq normal ,
+.Sq compress ,
+.Sq noicmp ,
+or
+.Sq autocomp
+which correspond respectively to
+.Sq use normal line discipline
+(no header compression),
+.Sq enable VJ header compression ,
+.Sq throw away ICMP packets ,
+and
+.Sq auto enable VJ header compression
+(only if the remote end of the link also supports it).
 .Pp
 Then a shell script is invoked to initialize the slip
 interface with the appropriate local and remote
 .Tn IP
 address,
 netmask, etc.
+.Pp
 The usual initialization script is
 .Pa /etc/sliphome/slip.login
 but, if particular hosts need special initialization, the file

usr.sbin/sliplogin/sliplogin.c

@@ -77,6 +77,7 @@ static char sccsid[] = "@(#)sliplogin.c	8.2 (Berkeley) 2/1/94";
 #include <termios.h>
 #include <sys/ioctl.h>
 #include <net/slip.h>
+#include <net/if.h>
 
 #include <stdio.h>
 #include <errno.h>
@@ -88,6 +89,7 @@ static char sccsid[] = "@(#)sliplogin.c	8.2 (Berkeley) 2/1/94";
 #include "pathnames.h"
 
 int	unit;
+int	slip_mode;
 speed_t speed;
 int	uid;
 int     keepal;
@@ -97,6 +99,17 @@ char	loginargs[BUFSIZ];
 char	loginfile[MAXPATHLEN];
 char	loginname[BUFSIZ];
 
+struct slip_modes {
+	char	*sm_name;
+	int	sm_or_flag;
+	int	sm_and_flag;
+}	 modes[] = {
+	"normal",	0        , 0        ,
+	"compress",	IFF_LINK0, IFF_LINK2,
+	"noicmp",	IFF_LINK1, 0        ,
+	"autocomp",	IFF_LINK2, IFF_LINK0,
+};
+
 void
 findid(name)
 	char *name;
@@ -134,6 +147,18 @@ findid(name)
 
 		(void) fclose(fp);
 
+		slip_mode = 0;
+		for (i = 0; i < n - 4; i++) {
+			for (j = 0; j < sizeof(modes)/sizeof(struct slip_modes);
+				j++) {
+				if (strcmp(modes[j].sm_name, slopt[i]) == 0) {
+					slip_mode |= (modes[j].sm_or_flag);
+					slip_mode &= ~(modes[j].sm_and_flag);
+					break;
+				}
+			}
+		}
+
 		/*
 		 * we've found the guy we're looking for -- see if
 		 * there's a login file we can use.  First check for
@@ -259,6 +284,40 @@ hup_handler(s)
 	/* NOTREACHED */
 }
 
+
+/* Modify the slip line mode and add any compression or no-icmp flags. */
+void line_flags(unit)
+	int unit;
+{
+	struct ifreq ifr;
+	int s;
+
+	/* open a socket as the handle to the interface */
+	s = socket(AF_INET, SOCK_DGRAM, 0);
+	if (s < 0) {
+		syslog(LOG_ERR, "socket: %m");
+		exit(1);
+	}
+	sprintf(ifr.ifr_name, "sl%d", unit);
+
+	/* get the flags for the interface */
+	if (ioctl(s, SIOCGIFFLAGS, (caddr_t)&ifr) < 0) {
+		syslog(LOG_ERR, "ioctl (SIOCGIFFLAGS): %m");
+		exit(1);
+        }
+
+	/* Assert any compression or no-icmp flags. */
+#define SLMASK (~(IFF_LINK0 | IFF_LINK1 | IFF_LINK2))
+	ifr.ifr_flags &= SLMASK;
+	ifr.ifr_flags |= slip_mode;
+	if (ioctl(s, SIOCSIFFLAGS, (caddr_t)&ifr) < 0) {
+		syslog(LOG_ERR, "ioctl (SIOCSIFFLAGS): %m");
+		exit(1);
+	}
+        close(s);
+}
+
+
 main(argc, argv)
 	int argc;
 	char *argv[];
@@ -386,6 +445,9 @@ main(argc, argv)
 		exit(6);
 	}
 
+	/* Handle any compression or no-icmp flags. */
+	line_flags(unit);
+
 	/* reset uid to users' to allow the user to give a signal. */
 	seteuid(uid);
 	/* twiddle thumbs until we get a signal */