tunctl: new applet by Vladimir

function                                             old     new   delta
tunctl_main                                            -     371    +371
packed_usage                                       25669   25799    +130
applet_names                                        1981    1988      +7
applet_main                                         1192    1196      +4
applet_nameofs                                       596     598      +2
applet_install_loc                                   149     150      +1
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 5/0 up/down: 515/0)             Total: 515 bytes

3 files changed, 154 insertions, 0 deletions

diff --git a/networking/Config.in b/networking/Config.in
index 00a07b479..b3d07e63c 100644
--- a/networking/Config.in
+++ b/networking/Config.in
@@ -920,6 +920,20 @@ config TCPSVD
 	  tcpsvd listens on a TCP port and runs a program for each new
 	  connection.
 
+config TUNCTL
+	bool "tunctl"
+	default n
+	help
+	  tunctl creates or deletes tun devices.
+
+config FEATURE_TUNCTL_UG
+	bool "Support owner:group assignment"
+	default n
+	depends on TUNCTL
+	help
+	  Allow to specify owner and group of newly created interface.
+	  340 bytes of pure bloat. Say no here.
+
 config UDPSVD
 	bool "udpsvd"
 	default n
diff --git a/networking/Kbuild b/networking/Kbuild
index 63d0745f8..77071269a 100644
--- a/networking/Kbuild
+++ b/networking/Kbuild
@@ -36,6 +36,7 @@ lib-$(CONFIG_TELNETD)      += telnetd.o
 lib-$(CONFIG_TFTP)         += tftp.o
 lib-$(CONFIG_TFTPD)        += tftp.o
 lib-$(CONFIG_TRACEROUTE)   += traceroute.o
+lib-$(CONFIG_TUNCTL)       += tunctl.o
 lib-$(CONFIG_VCONFIG)      += vconfig.o
 lib-$(CONFIG_WGET)         += wget.o
 lib-$(CONFIG_ZCIP)         += zcip.o
diff --git a/networking/tunctl.c b/networking/tunctl.c
new file mode 100644
index 000000000..a8e5270ad
--- /dev/null
+++ b/networking/tunctl.c
@@ -0,0 +1,139 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * tun devices controller
+ *
+ * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
+ *
+ * Original code:
+ *      Jeff Dike
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ */
+#include <netinet/in.h>
+#include <net/if.h>
+#include <linux/if_tun.h>
+#include "libbb.h"
+
+/* TUNSETGROUP appeared in 2.6.23 */
+#ifndef TUNSETGROUP
+#define TUNSETGROUP _IOW('T', 206, int)
+#endif
+
+#define IOCTL(a, b, c) ioctl_or_perror_and_die(a, b, c, NULL)
+
+#if 1
+
+int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int tunctl_main(int argc UNUSED_PARAM, char **argv)
+{
+	struct ifreq ifr;
+	int fd;
+	const char *opt_name = "tap%d";
+	const char *opt_device = "/dev/net/tun";
+#if ENABLE_FEATURE_TUNCTL_UG
+	const char *opt_user, *opt_group;
+	long user = -1, group = -1;
+#endif
+	unsigned opts;
+
+	enum {
+		OPT_f = 1 << 0, // control device name (/dev/net/tun)
+		OPT_t = 1 << 1, // create named interface
+		OPT_d = 1 << 2, // delete named interface
+#if ENABLE_FEATURE_TUNCTL_UG
+		OPT_u = 1 << 3, // set new interface owner
+		OPT_g = 1 << 4, // set new interface group
+		OPT_b = 1 << 5, // brief output
+#endif
+	};
+
+	opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
+	opts = getopt32(argv, "f:t:d:" USE_FEATURE_TUNCTL_UG("u:g:b"),
+			&opt_device, &opt_name, &opt_name
+			USE_FEATURE_TUNCTL_UG(, &opt_user, &opt_group));
+
+	// select device
+	memset(&ifr, 0, sizeof(ifr));
+	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+	strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
+
+	// open device
+	fd = xopen(opt_device, O_RDWR);
+	IOCTL(fd, TUNSETIFF, (void *)&ifr);
+
+	// delete?
+	if (opts & OPT_d) {
+		IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)0);
+		bb_info_msg("Set '%s' %spersistent", ifr.ifr_name, "non");
+		return EXIT_SUCCESS;
+	}
+
+	// create
+#if ENABLE_FEATURE_TUNCTL_UG
+	if (opts & OPT_g) {
+		group = xgroup2gid(opt_group);
+		IOCTL(fd, TUNSETGROUP, (void *)(uintptr_t)group);
+	} else
+		user = geteuid();
+	if (opts & OPT_u)
+		user = xuname2uid(opt_user);
+	IOCTL(fd, TUNSETOWNER, (void *)(uintptr_t)user);
+#endif
+	IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)1);
+
+	// show info
+#if ENABLE_FEATURE_TUNCTL_UG
+	if (opts & OPT_b) {
+		puts(ifr.ifr_name);
+	} else {
+		printf("Set '%s' %spersistent", ifr.ifr_name, "");
+		printf(" and owned by uid %ld", user);
+		if (group != -1)
+			printf(" gid %ld", group);
+		bb_putchar('\n');
+	}
+#else
+	puts(ifr.ifr_name);
+#endif
+	return EXIT_SUCCESS;
+}
+
+#else
+
+/* -210 bytes: */
+
+int tunctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int tunctl_main(int argc UNUSED_PARAM, char **argv)
+{
+	struct ifreq ifr;
+	int fd;
+	const char *opt_name = "tap%d";
+	const char *opt_device = "/dev/net/tun";
+	unsigned opts;
+
+	enum {
+		OPT_f = 1 << 0, // control device name (/dev/net/tun)
+		OPT_t = 1 << 1, // create named interface
+		OPT_d = 1 << 2, // delete named interface
+	};
+
+	opt_complementary = "=0:t--d:d--t"; // no arguments; t ^ d
+	opts = getopt32(argv, "f:t:d:u:g:b", // u, g, b accepted and ignored
+			&opt_device, &opt_name, &opt_name, NULL, NULL);
+
+	// set interface name
+	memset(&ifr, 0, sizeof(ifr));
+	ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
+	strncpy_IFNAMSIZ(ifr.ifr_name, opt_name);
+
+	// open device
+	fd = xopen(opt_device, O_RDWR);
+	IOCTL(fd, TUNSETIFF, (void *)&ifr);
+
+	// create or delete interface
+	IOCTL(fd, TUNSETPERSIST, (void *)(uintptr_t)(0 == (opts & OPT_d)));
+
+	return EXIT_SUCCESS;
+}
+
+#endif