Re: rename ppp interface

[Arvin Schnell <arvin@suse.de>]

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On Mon, Jul 19, 2004 at 10:10:43AM +1000, James Cameron wrote:
> I'm certainly interested in the patch; in the PPTP projects we regularly
> get "change the interface name" as a wishlist request.  Can you tell me
> which kernel version range supports the ioctl?

I think the ioctl was added for kernel 2.6, but I might be wrong.
Likely the code should be placed in ifdef's.

> I'm not qualified to judge any other impacts of the change.

The only problem I found is when you try to rename several
interfaces to pppN.  Also I didn't test multilink.

Attached is an enhanced patch.

ciao Arvin

-- 
Dipl.-Phys. Arvin Schnell
SuSE Linux AG
Research & Development
email: arvin@suse.de

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--- ./pppd/main.c.orig	2004-07-19 12:35:22.000000000 +0000
+++ ./pppd/main.c	2004-07-19 14:34:38.542120946 +0000
@@ -98,7 +98,7 @@
 static const char rcsid[] = RCSID;
 
 /* interface vars */
-char ifname[32];		/* Interface name */
+char ifname[MAXIFNAMELEN];	/* Interface name */
 int ifunit;			/* Interface unit number */
 
 struct channel *the_channel;
@@ -261,13 +261,6 @@
     NULL
 };
 
-/*
- * If PPP_DRV_NAME is not defined, use the default "ppp" as the device name.
- */
-#if !defined(PPP_DRV_NAME)
-#define PPP_DRV_NAME	"ppp"
-#endif /* !defined(PPP_DRV_NAME) */
-
 int
 main(argc, argv)
     int argc;
@@ -777,8 +770,11 @@
 set_ifunit(iskey)
     int iskey;
 {
-    info("Using interface %s%d", PPP_DRV_NAME, ifunit);
+    if (req_ifname[0] != '\0')
+	slprintf(ifname, sizeof(ifname), req_ifname);
+    else
     slprintf(ifname, sizeof(ifname), "%s%d", PPP_DRV_NAME, ifunit);
+    info("Using interface %s", ifname);
     script_setenv("IFNAME", ifname, iskey);
     if (iskey) {
 	create_pidfile(getpid());	/* write pid to file */
--- ./pppd/options.c.orig	2004-07-19 12:59:21.000000000 +0000
+++ ./pppd/options.c	2004-07-19 14:35:04.253865964 +0000
@@ -102,6 +102,7 @@
 bool	tune_kernel;		/* may alter kernel settings */
 int	connect_delay = 1000;	/* wait this many ms after connect script */
 int	req_unit = -1;		/* requested interface unit */
+char	req_ifname[MAXIFNAMELEN];	/* requested interface name */
 bool	multilink = 0;		/* Enable multilink operation */
 char	*bundle_name = NULL;	/* bundle name for multilink */
 bool	dump_options;		/* print out option values */
@@ -259,6 +260,10 @@
       "PPP interface unit number to use if possible",
       OPT_PRIO | OPT_LLIMIT, 0, 0 },
 
+    { "ifname", o_string, req_ifname,
+      "Set PPP interface name",
+      OPT_PRIO | OPT_PRIV | OPT_STATIC, NULL, MAXIFNAMELEN },
+
     { "dump", o_bool, &dump_options,
       "Print out option values after parsing all options", 1 },
     { "dryrun", o_bool, &dryrun,
--- ./pppd/pppd.8.orig	2004-07-19 14:39:06.639320497 +0000
+++ ./pppd/pppd.8	2004-07-19 15:00:37.339448432 +0000
@@ -1020,7 +1020,12 @@
 .TP
 .B unit \fInum
 Sets the ppp unit number (for a ppp0 or ppp1 etc interface name) for outbound
-connections.
+connections.  If the unit is already in use a dynamically allocated will be
+used.
+.TP
+.B ifname \fIstring
+Set the ppp interface name for outbound connections.  A failure to set the
+name will terminate the pppd.
 .TP
 .B updetach
 With this option, pppd will detach from its controlling terminal once
--- ./pppd/pppd.h.orig	2004-07-19 12:59:16.000000000 +0000
+++ ./pppd/pppd.h	2004-07-19 15:02:08.792752747 +0000
@@ -80,6 +80,16 @@
 #define MAXARGS		1	/* max # args to a command */
 #define MAXNAMELEN	256	/* max length of hostname or name for auth */
 #define MAXSECRETLEN	256	/* max length of password or secret */
+#define MAXIFNAMELEN	32	/* max length of interface name; or use IFNAMSIZ, can we
+				   always include net/if.h? */
+
+/*
+ * If PPP_DRV_NAME is not defined, use the default "ppp" as the device name.
+ * Where should PPP_DRV_NAME come from? Do we include it here?
+ */
+#if !defined(PPP_DRV_NAME)
+#define PPP_DRV_NAME	"ppp"
+#endif /* !defined(PPP_DRV_NAME) */
 
 /*
  * Option descriptor structure.
@@ -304,6 +314,7 @@
 extern int	connect_delay;	/* Time to delay after connect script */
 extern int	max_data_rate;	/* max bytes/sec through charshunt */
 extern int	req_unit;	/* interface unit number to use */
+extern char	req_ifname[MAXIFNAMELEN];	/* interface name to use */
 extern bool	multilink;	/* enable multilink operation */
 extern bool	noendpoint;	/* don't send or accept endpt. discrim. */
 extern char	*bundle_name;	/* bundle name for multilink */
--- ./pppd/sys-linux.c.orig	2004-07-19 12:33:29.000000000 +0000
+++ ./pppd/sys-linux.c	2004-07-19 14:37:36.463754450 +0000
@@ -649,6 +649,21 @@
 	}
 	if (x < 0)
 		error("Couldn't create new ppp unit: %m");
+
+	if (x == 0 && req_ifname[0] != '\0') {
+		struct ifreq ifr;
+		char t[MAXIFNAMELEN];
+		memset(&ifr, 0, sizeof(struct ifreq));
+		slprintf(t, sizeof(t), "%s%d", PPP_DRV_NAME, ifunit);
+		strncpy(ifr.ifr_name, t, IF_NAMESIZE);
+		strncpy(ifr.ifr_newname, req_ifname, IF_NAMESIZE);
+		x = ioctl(sock_fd, SIOCSIFNAME, &ifr);
+		if (x < 0)
+		    error("Couldn't rename interface %s to %s: %m", t, req_ifname);
+		else
+		    info("Renamed interface %s to %s", t, req_ifname);
+	}
+
 	return x;
 }