path: root/Documentation/networking/ifenslave.c

/* Mode: C;
 * ifenslave.c: Configure network interfaces for parallel routing.
 *
 *	This program controls the Linux implementation of running multiple
 *	network interfaces in parallel.
 *
 * Author:	Donald Becker <becker@cesdis.gsfc.nasa.gov>
 *		Copyright 1994-1996 Donald Becker
 *
 *		This program is free software; you can redistribute it
 *		and/or modify it under the terms of the GNU General Public
 *		License as published by the Free Software Foundation.
 *
 *	The author may be reached as becker@CESDIS.gsfc.nasa.gov, or C/O
 *	Center of Excellence in Space Data and Information Sciences
 *	   Code 930.5, Goddard Space Flight Center, Greenbelt MD 20771
 *
 *  Changes :
 *    - 2000/10/02 Willy Tarreau <willy at meta-x.org> :
 *       - few fixes. Master's MAC address is now correctly taken from
 *         the first device when not previously set ;
 *       - detach support : call BOND_RELEASE to detach an enslaved interface.
 *       - give a mini-howto from command-line help : # ifenslave -h
 *
 *    - 2001/02/16 Chad N. Tindel <ctindel at ieee dot org> :
 *       - Master is now brought down before setting the MAC address.  In
 *         the 2.4 kernel you can't change the MAC address while the device is
 *         up because you get EBUSY.
 *
 *    - 2001/09/13 Takao Indoh <indou dot takao at jp dot fujitsu dot com>
 *       - Added the ability to change the active interface on a mode 1 bond
 *         at runtime.
 *
 *    - 2001/10/23 Chad N. Tindel <ctindel at ieee dot org> :
 *       - No longer set the MAC address of the master.  The bond device will
 *         take care of this itself
 *       - Try the SIOC*** versions of the bonding ioctls before using the
 *         old versions
 *    - 2002/02/18 Erik Habbinga <erik_habbinga @ hp dot com> :
 *       - ifr2.ifr_flags was not initialized in the hwaddr_notset case,
 *         SIOCGIFFLAGS now called before hwaddr_notset test
 *
 *    - 2002/10/31 Tony Cureington <tony.cureington * hp_com> :
 *       - If the master does not have a hardware address when the first slave
 *         is enslaved, the master is assigned the hardware address of that
 *         slave - there is a comment in bonding.c stating "ifenslave takes
 *         care of this now." This corrects the problem of slaves having
 *         different hardware addresses in active-backup mode when
 *         multiple interfaces are specified on a single ifenslave command
 *         (ifenslave bond0 eth0 eth1).
 *
 *    - 2003/03/18 - Tsippy Mendelson <tsippy.mendelson at intel dot com> and
 *                   Shmulik Hen <shmulik.hen at intel dot com>
 *       - Moved setting the slave's mac address and openning it, from
 *         the application to the driver. This enables support of modes
 *         that need to use the unique mac address of each slave.
 *         The driver also takes care of closing the slave and restoring its
 *         original mac address upon release.
 *         In addition, block possibility of enslaving before the master is up.
 *         This prevents putting the system in an undefined state.
 *
 *    - 2003/05/01 - Amir Noam <amir.noam at intel dot com>
 *       - Added ABI version control to restore compatibility between
 *         new/old ifenslave and new/old bonding.
 *       - Prevent adding an adapter that is already a slave.
 *         Fixes the problem of stalling the transmission and leaving
 *         the slave in a down state.
 *
 *    - 2003/05/01 - Shmulik Hen <shmulik.hen at intel dot com>
 *       - Prevent enslaving if the bond device is down.
 *         Fixes the problem of leaving the system in unstable state and
 *         halting when trying to remove the module.
 *       - Close socket on all abnormal exists.
 *       - Add versioning scheme that follows that of the bonding driver.
 *         current version is 1.0.0 as a base line.
 *
 *    - 2003/05/22 - Jay Vosburgh <fubar at us dot ibm dot com>
 *	 - ifenslave -c was broken; it's now fixed
 *	 - Fixed problem with routes vanishing from master during enslave
 *	   processing.
 *
 *    - 2003/05/27 - Amir Noam <amir.noam at intel dot com>
 *	 - Fix backward compatibility issues:
 *	   For drivers not using ABI versions, slave was set down while
 *	   it should be left up before enslaving.
 *	   Also, master was not set down and the default set_mac_address()
 *	   would fail and generate an error message in the system log.
 * 	 - For opt_c: slave should not be set to the master's setting
 *	   while it is running. It was already set during enslave. To
 *	   simplify things, it is now handled separately.
 *
 *    - 2003/12/01 - Shmulik Hen <shmulik.hen at intel dot com>
 *	 - Code cleanup and style changes
 *	   set version to 1.1.0
 */

#define APP_VERSION	"1.1.0"
#define APP_RELDATE	"December 1, 2003"
#define APP_NAME	"ifenslave"

static char *version =
APP_NAME ".c:v" APP_VERSION " (" APP_RELDATE ")\n"
"o Donald Becker (becker@cesdis.gsfc.nasa.gov).\n"
"o Detach support added on 2000/10/02 by Willy Tarreau (willy at meta-x.org).\n"
"o 2.4 kernel support added on 2001/02/16 by Chad N. Tindel\n"
"  (ctindel at ieee dot org).\n";

static const char *usage_msg =
"Usage: ifenslave [-f] <master-if> <slave-if> [<slave-if>...]\n"
"       ifenslave -d   <master-if> <slave-if> [<slave-if>...]\n"
"       ifenslave -c   <master-if> <slave-if>\n"
"       ifenslave --help\n";

static const char *help_msg =
"\n"
"       To create a bond device, simply follow these three steps :\n"
"       - ensure that the required drivers are properly loaded :\n"
"         # modprobe bonding ; modprobe <3c59x|eepro100|pcnet32|tulip|...>\n"
"       - assign an IP address to the bond device :\n"
"         # ifconfig bond0 <addr> netmask <mask> broadcast <bcast>\n"
"       - attach all the interfaces you need to the bond device :\n"
"         # ifenslave [{-f|--force}] bond0 eth0 [eth1 [eth2]...]\n"
"         If bond0 didn't have a MAC address, it will take eth0's. Then, all\n"
"         interfaces attached AFTER this assignment will get the same MAC addr.\n"
"         (except for ALB/TLB modes)\n"
"\n"
"       To set the bond device down and automatically release all the slaves :\n"
"         # ifconfig bond0 down\n"
"\n"
"       To detach a dead interface without setting the bond device down :\n"
"         # ifenslave {-d|--detach} bond0 eth0 [eth1 [eth2]...]\n"
"\n"
"       To change active slave :\n"
"         # ifenslave {-c|--change-active} bond0 eth0\n"
"\n"
"       To show master interface info\n"
"         # ifenslave bond0\n"
"\n"
"       To show all interfaces info\n"
"       # ifenslave {-a|--all-interfaces}\n"
"\n"
"       To be more verbose\n"
"       # ifenslave {-v|--verbose} ...\n"
"\n"
"       # ifenslave {-u|--usage}   Show usage\n"
"       # ifenslave {-V|--version} Show version\n"
"       # ifenslave {-h|--help}    This message\n"
"\n";

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/if.h>
#include <net/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_bonding.h>
#include <linux/sockios.h>

typedef unsigned long long u64;	/* hack, so we may include kernel's ethtool.h */
typedef __uint32_t u32;		/* ditto */
typedef __uint16_t u16;		/* ditto */
typedef __uint8_t u8;		/* ditto */
#include <linux/ethtool.h>

struct option longopts[] = {
	/* { name  has_arg  *flag  val } */
	{"all-interfaces",	0, 0, 'a'},	/* Show all interfaces. */
	{"change-active",	0, 0, 'c'},	/* Change the active slave.  */
	{"detach",		0, 0, 'd'},	/* Detach a slave interface. */
	{"force",		0, 0, 'f'},	/* Force the operation. */
	{"help",		0, 0, 'h'},	/* Give help */
	{"usage",		0, 0, 'u'},	/* Give usage */
	{"verbose",		0, 0, 'v'},	/* Report each action taken. */
	{"version",		0, 0, 'V'},	/* Emit version information. */
	{ 0, 0, 0, 0}
};

/* Command-line flags. */
unsigned int
opt_a = 0,	/* Show-all-interfaces flag. */
opt_c = 0,	/* Change-active-slave flag. */
opt_d = 0,	/* Detach a slave interface. */
opt_f = 0,	/* Force the operation. */
opt_h = 0,	/* Help */
opt_u = 0,	/* Usage */
opt_v = 0,	/* Verbose flag. */
opt_V = 0;	/* Version */

int skfd = -1;		/* AF_INET socket for ioctl() calls.*/
int abi_ver = 0;	/* userland - kernel ABI version */
int hwaddr_set = 0;	/* Master's hwaddr is set */
int saved_errno;

struct ifreq master_mtu, master_flags, master_hwaddr;
struct ifreq slave_mtu, slave_flags, slave_hwaddr;

struct dev_ifr {
	struct ifreq *req_ifr;
	char *req_name;
	int req_type;
};

struct dev_ifr master_ifra[] = {
	{&master_mtu,     "SIOCGIFMTU",     SIOCGIFMTU},
	{&master_flags,   "SIOCGIFFLAGS",   SIOCGIFFLAGS},
	{&master_hwaddr,  "SIOCGIFHWADDR",  SIOCGIFHWADDR},
	{NULL, "", 0}
};

struct dev_ifr slave_ifra[] = {
	{&slave_mtu,     "SIOCGIFMTU",     SIOCGIFMTU},
	{&slave_flags,   "SIOCGIFFLAGS",   SIOCGIFFLAGS},
	{&slave_hwaddr,  "SIOCGIFHWADDR",  SIOCGIFHWADDR},
	{NULL, "", 0}
};

static void if_print(char *ifname);
static int get_drv_info(char *master_ifname);
static int get_if_settings(char *ifname, struct dev_ifr ifra[]);
static int get_slave_flags(char *slave_ifname);
static int set_master_hwaddr(char *master_ifname, struct sockaddr *hwaddr);
static int set_slave_hwaddr(char *slave_ifname, struct sockaddr *hwaddr);
static int set_slave_mtu(char *slave_ifname, int mtu);
static int set_if_flags(char *ifname, short flags);
static int set_if_up(char *ifname, short flags);
static int set_if_down(char *ifname, short flags);
static int clear_if_addr(char *ifname);
static int set_if_addr(char *master_ifname, char *slave_ifname);
static int change_active(char *master_ifname, char *slave_ifname);
static int enslave(char *master_ifname, char *slave_ifname);
static int release(char *master_ifname, char *slave_ifname);
#define v_print(fmt, args...)	\
	if (opt_v)		\
		fprintf(stderr, fmt, ## args )

int main(int argc, char *argv[])
{
	char **spp, *master_ifname, *slave_ifname;
	int c, i, rv;
	int res = 0;
	int exclusive = 0;

	while ((c = getopt_long(argc, argv, "acdfhuvV", longopts, 0)) != EOF) {
		switch (c) {
		case 'a': opt_a++; exclusive++; break;
		case 'c': opt_c++; exclusive++; break;
		case 'd': opt_d++; exclusive++; break;
		case 'f': opt_f++; exclusive++; break;
		case 'h': opt_h++; exclusive++; break;
		case 'u': opt_u++; exclusive++; break;
		case 'v': opt_v++; break;
		case 'V': opt_V++; exclusive++; break;

		case '?':
			fprintf(stderr, usage_msg);
			res = 2;
			goto out;
		}
	}

	/* options check */
	if (exclusive > 1) {
		fprintf(stderr, usage_msg);
		res = 2;
		goto out;
	}

	if (opt_v || opt_V) {
		printf(version);
		if (opt_V) {
			res = 0;
			goto out;
		}
	}

	if (opt_u) {
		printf(usage_msg);
		res = 0;
		goto out;
	}

	if (opt_h) {
		printf(usage_msg);
		printf(help_msg);
		res = 0;
		goto out;
	}

	/* Open a basic socket */
	if ((skfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
		perror("socket");
		res = 1;
		goto out;
	}

	if (opt_a) {
		if (optind == argc) {
			/* No remaining args */
			/* show all interfaces */
			if_print((char *)NULL);
			goto out;
		} else {
			/* Just show usage */
			fprintf(stderr, usage_msg);
			res = 2;
			goto out;
		}
	}

	/* Copy the interface name */
	spp = argv + optind;
	master_ifname = *spp++;

	if (master_ifname == NULL) {
		fprintf(stderr, usage_msg);
		res = 2;
		goto out;
	}

	/* exchange abi version with bonding module */
	res = get_drv_info(master_ifname);
	if (res) {
		fprintf(stderr,
			"Master '%s': Error: handshake with driver failed. "
			"Aborting\n",
			master_ifname);
		goto out;
	}

	slave_ifname = *spp++;

	if (slave_ifname == NULL) {
		if (opt_d || opt_c) {
			fprintf(stderr, usage_msg);
			res = 2;
			goto out;
		}

		/* A single arg means show the
		 * configuration for this interface
		 */
		if_print(master_ifname);
		goto out;
	}

	res = get_if_settings(master_ifname, master_ifra);
	if (res) {
		/* Probably a good reason not to go on */
		fprintf(stderr,
			"Master '%s': Error: get settings failed: %s. "
			"Aborting\n",
			master_ifname, strerror(res));
		goto out;
	}

	/* check if master is indeed a master;
	 * if not then fail any operation
	 */
	if (!(master_flags.ifr_flags & IFF_MASTER)) {
		fprintf(stderr,
			"Illegal operation; the specified interface '%s' "
			"is not a master. Aborting\n",
			master_ifname);
		res = 1;
		goto out;
	}

	/* check if master is up; if not then fail any operation */
	if (!(master_flags.ifr_flags & IFF_UP)) {
		fprintf(stderr,
			"Illegal operation; the specified master interface "
			"'%s' is not up.\n",
			master_ifname);
		res = 1;
		goto out;
	}

	/* Only for enslaving */
	if (!opt_c && !opt_d) {
		sa_family_t master_family = master_hwaddr.ifr_hwaddr.sa_family;
		unsigned char *hwaddr =
			(unsigned char *)master_hwaddr.ifr_hwaddr.sa_data;

		/* The family '1' is ARPHRD_ETHER for ethernet. */
		if (master_family != 1 && !opt_f) {
			fprintf(stderr,
				"Illegal operation: The specified master "
				"interface '%s' is not ethernet-like.\n "
				"This program is designed to work with "
				"ethernet-like network interfaces.\n "
				"Use the '-f' option to force the "
				"operation.\n",
				master_ifname);
			res = 1;
			goto out;
		}

		/* Check master's hw addr */
		for (i = 0; i < 6; i++) {
			if (hwaddr[i] != 0) {
				hwaddr_set = 1;
				break;
			}
		}

		if (hwaddr_set) {
			v_print("current hardware address of master '%s' "
				"is %2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x, "
				"type %d\n",
				master_ifname,
				hwaddr[0], hwaddr[1],
				hwaddr[2], hwaddr[3],
				hwaddr[4], hwaddr[5],
				master_family);
		}
	}

	/* Accepts only one slave */
	if (opt_c) {
		/* change active slave */
		res = get_slave_flags(slave_ifname);
		if (res) {
			fprintf(stderr,
				"Slave '%s': Error: get flags failed. "
				"Aborting\n",
				slave_ifname);
			goto out;
		}
		res = change_active(master_ifname, slave_ifname);
		if (res) {
			fprintf(stderr,
				"Master '%s', Slave '%s': Error: "
				"Change active failed\n",
				master_ifname, slave_ifname);
		}
	} else {
		/* Accept multiple slaves */
		do {
			if (opt_d) {
				/* detach a slave interface from the master */
				rv = get_slave_flags(slave_ifname);
				if (rv) {
					/* Can't work with this slave. */
					/* remember the error and skip it*/
					fprintf(stderr,
						"Slave '%s': Error: get flags "
						"failed. Skipping\n",
						slave_ifname);
					res = rv;
					continue;
				}
				rv = release(master_ifname, slave_ifname);
				if (rv) {
					fprintf(stderr,
						"Master '%s', Slave '%s': Error: "
						"Release failed\n",
						master_ifname, slave_ifname);
					res = rv;
				}
			} else {
				/* attach a slave interface to the master */
				rv = get_if_settings(slave_ifname, slave_ifra);
				if (rv) {
					/* Can't work with this slave. */
					/* remember the error and skip it*/
					fprintf(stderr,
						"Slave '%s': Error: get "
						"settings failed: %s. "
						"Skipping\n",
						slave_ifname, strerror(rv));
					res = rv;
					continue;
				}
				rv = enslave(master_ifname, slave_ifname);
				if (rv) {
					fprintf(stderr,
						"Master '%s', Slave '%s': Error: "
						"Enslave failed\n",
						master_ifname, slave_ifname);
					res = rv;
				}
			}
		} while ((slave_ifname = *spp++) != NULL);
	}

out:
	if (skfd >= 0) {
		close(skfd);
	}

	return res;
}

static short mif_flags;

/* Get the inteface configuration from the kernel. */
static int if_getconfig(char *ifname)
{
	struct ifreq ifr;
	int metric, mtu;	/* Parameters of the master interface. */
	struct sockaddr dstaddr, broadaddr, netmask;
	unsigned char *hwaddr;

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFFLAGS, &ifr) < 0)
		return -1;
	mif_flags = ifr.ifr_flags;
	printf("The result of SIOCGIFFLAGS on %s is %x.\n",
	       ifname, ifr.ifr_flags);

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFADDR, &ifr) < 0)
		return -1;
	printf("The result of SIOCGIFADDR is %2.2x.%2.2x.%2.2x.%2.2x.\n",
	       ifr.ifr_addr.sa_data[0], ifr.ifr_addr.sa_data[1],
	       ifr.ifr_addr.sa_data[2], ifr.ifr_addr.sa_data[3]);

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFHWADDR, &ifr) < 0)
		return -1;

	/* Gotta convert from 'char' to unsigned for printf(). */
	hwaddr = (unsigned char *)ifr.ifr_hwaddr.sa_data;
	printf("The result of SIOCGIFHWADDR is type %d  "
	       "%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x.\n",
	       ifr.ifr_hwaddr.sa_family, hwaddr[0], hwaddr[1],
	       hwaddr[2], hwaddr[3], hwaddr[4], hwaddr[5]);

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFMETRIC, &ifr) < 0) {
		metric = 0;
	} else
		metric = ifr.ifr_metric;

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFMTU, &ifr) < 0)
		mtu = 0;
	else
		mtu = ifr.ifr_mtu;

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFDSTADDR, &ifr) < 0) {
		memset(&dstaddr, 0, sizeof(struct sockaddr));
	} else
		dstaddr = ifr.ifr_dstaddr;

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFBRDADDR, &ifr) < 0) {
		memset(&broadaddr, 0, sizeof(struct sockaddr));
	} else
		broadaddr = ifr.ifr_broadaddr;

	strcpy(ifr.ifr_name, ifname);
	if (ioctl(skfd, SIOCGIFNETMASK, &ifr) < 0) {
		memset(&netmask, 0, sizeof(struct sockaddr));
	} else
		netmask = ifr.ifr_netmask;

	return 0;
}

static void if_print(char *ifname)
{
	char buff[1024];
	struct ifconf ifc;
	struct ifreq *ifr;
	int i;

	if (ifname == (char *)NULL) {
		ifc.ifc_len = sizeof(buff);
		ifc.ifc_buf = buff;
		if (ioctl(skfd, SIOCGIFCONF, &ifc) < 0) {
			perror("SIOCGIFCONF failed");
			return;
		}

		ifr = ifc.ifc_req;
		for (i = ifc.ifc_len / sizeof(struct ifreq); --i >= 0; ifr++) {
			if (if_getconfig(ifr->ifr_name) < 0) {
				fprintf(stderr,
					"%s: unknown interface.\n",
					ifr->ifr_name);
				continue;
			}

			if (((mif_flags & IFF_UP) == 0) && !opt_a) continue;
			/*ife_print(&ife);*/
		}
	} else {
		if (if_getconfig(ifname) < 0) {
			fprintf(stderr,
				"%s: unknown interface.\n", ifname);
		}
	}
}

static int get_drv_info(char *master_ifname)
{
	struct ifreq ifr;
	struct ethtool_drvinfo info;
	char *endptr;

	memset(&ifr, 0, sizeof(ifr));
	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
	ifr.ifr_data = (caddr_t)&info;

	info.cmd = ETHTOOL_GDRVINFO;
	strncpy(info.driver, "ifenslave", 32);
	snprintf(info.fw_version, 32, "%d", BOND_ABI_VERSION);

	if (ioctl(skfd, SIOCETHTOOL, &ifr) < 0) {
		if (errno == EOPNOTSUPP) {
			goto out;
		}

		saved_errno = errno;
		v_print("Master '%s': Error: get bonding info failed %s\n",
			master_ifname, strerror(saved_errno));
		return 1;
	}

	abi_ver = strtoul(info.fw_version, &endptr, 0);
	if (*endptr) {
                v_print("Master '%s': Error: got invalid string as an ABI "
			"version from the bonding module\n",
			master_ifname);
		return 1;
	}

out:
	v_print("ABI ver is %d\n", abi_ver);

	return 0;
}

static int change_active(char *master_ifname, char *slave_ifname)
{
	struct ifreq ifr;
	int res = 0;

	if (!(slave_flags.ifr_flags & IFF_SLAVE)) {
		fprintf(stderr,
			"Illegal operation: The specified slave interface "
			"'%s' is not a slave\n",
			slave_ifname);
		return 1;
	}

	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
	strncpy(ifr.ifr_slave, slave_ifname, IFNAMSIZ);
	if ((ioctl(skfd, SIOCBONDCHANGEACTIVE, &ifr) < 0) &&
	    (ioctl(skfd, BOND_CHANGE_ACTIVE_OLD, &ifr) < 0)) {
		saved_errno = errno;
		v_print("Master '%s': Error: SIOCBONDCHANGEACTIVE failed: "
			"%s\n",
			master_ifname, strerror(saved_errno));
		res = 1;
	}

	return res;
}

static int enslave(char *master_ifname, char *slave_ifname)
{
	struct ifreq ifr;
	int res = 0;

	if (slave_flags.ifr_flags & IFF_SLAVE) {
		fprintf(stderr,
			"Illegal operation: The specified slave interface "
			"'%s' is already a slave\n",
			slave_ifname);
		return 1;
	}

	res = set_if_down(slave_ifname, slave_flags.ifr_flags);
	if (res) {
		fprintf(stderr,
			"Slave '%s': Error: bring interface down failed\n",
			slave_ifname);
		return res;
	}

	if (abi_ver < 2) {
		/* Older bonding versions would panic if the slave has no IP
		 * address, so get the IP setting from the master.
		 */
		set_if_addr(master_ifname, slave_ifname);
	} else {
		res = clear_if_addr(slave_ifname);
		if (res) {
			fprintf(stderr,
				"Slave '%s': Error: clear address failed\n",
				slave_ifname);
			return res;
		}
	}

	if (master_mtu.ifr_mtu != slave_mtu.ifr_mtu) {
		res = set_slave_mtu(slave_ifname, master_mtu.ifr_mtu);
		if (res) {
			fprintf(stderr,
				"Slave '%s': Error: set MTU failed\n",
				slave_ifname);
			return res;
		}
	}

	if (hwaddr_set) {
		/* Master already has an hwaddr
		 * so set it's hwaddr to the slave
		 */
		if (abi_ver < 1) {
			/* The driver is using an old ABI, so
			 * the application sets the slave's
			 * hwaddr
			 */
			res = set_slave_hwaddr(slave_ifname,
					       &(master_hwaddr.ifr_hwaddr));
			if (res) {
				fprintf(stderr,
					"Slave '%s': Error: set hw address "
					"failed\n",
					slave_ifname);
				goto undo_mtu;
			}

			/* For old ABI the application needs to bring the
			 * slave back up
			 */
			res = set_if_up(slave_ifname, slave_flags.ifr_flags);
			if (res) {
				fprintf(stderr,
					"Slave '%s': Error: bring interface "
					"down failed\n",
					slave_ifname);
				goto undo_slave_mac;
			}
		}
		/* The driver is using a new ABI,
		 * so the driver takes care of setting
		 * the slave's hwaddr and bringing
		 * it up again
		 */
	} else {
		/* No hwaddr for master yet, so
		 * set the slave's hwaddr to it
		 */
		if (abi_ver < 1) {
			/* For old ABI, the master needs to be
			 * down before setting it's hwaddr
			 */
			res = set_if_down(master_ifname, master_flags.ifr_flags);
			if (res) {
				fprintf(stderr,
					"Master '%s': Error: bring interface "
					"down failed\n",
					master_ifname);
				goto undo_mtu;
			}
		}

		res = set_master_hwaddr(master_ifname,
					&(slave_hwaddr.ifr_hwaddr));
		if (res) {
			fprintf(stderr,
				"Master '%s': Error: set hw address "
				"failed\n",
				master_ifname);
			goto undo_mtu;
		}

		if (abi_ver < 1) {
			/* For old ABI, bring the master
			 * back up
			 */
			res = set_if_up(master_ifname, master_flags.ifr_flags);
			if (res) {
				fprintf(stderr,
					"Master '%s': Error: bring interface "
					"up failed\n",
					master_ifname);
				goto undo_master_mac;
			}
		}

		hwaddr_set = 1;
	}

	/* Do the real thing */
	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
	strncpy(ifr.ifr_slave, slave_ifname, IFNAMSIZ);
	if ((ioctl(skfd, SIOCBONDENSLAVE, &ifr) < 0) &&
	    (ioctl(skfd, BOND_ENSLAVE_OLD, &ifr) < 0)) {
		saved_errno = errno;
		v_print("Master '%s': Error: SIOCBONDENSLAVE failed: %s\n",
			master_ifname, strerror(saved_errno));
		res = 1;
	}

	if (res) {
		goto undo_master_mac;
	}

	return 0;

/* rollback (best effort) */
undo_master_mac:
	set_master_hwaddr(master_ifname, &(master_hwaddr.ifr_hwaddr));
	hwaddr_set = 0;
	goto undo_mtu;
undo_slave_mac:
	set_slave_hwaddr(slave_ifname, &(slave_hwaddr.ifr_hwaddr));
undo_mtu:
	set_slave_mtu(slave_ifname, slave_mtu.ifr_mtu);
	return res;
}

static int release(char *master_ifname, char *slave_ifname)
{
	struct ifreq ifr;
	int res = 0;

	if (!(slave_flags.ifr_flags & IFF_SLAVE)) {
		fprintf(stderr,
			"Illegal operation: The specified slave interface "
			"'%s' is not a slave\n",
			slave_ifname);
		return 1;
	}

	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
	strncpy(ifr.ifr_slave, slave_ifname, IFNAMSIZ);
	if ((ioctl(skfd, SIOCBONDRELEASE, &ifr) < 0) &&
	    (ioctl(skfd, BOND_RELEASE_OLD, &ifr) < 0)) {
		saved_errno = errno;
		v_print("Master '%s': Error: SIOCBONDRELEASE failed: %s\n",
			master_ifname, strerror(saved_errno));
		return 1;
	} else if (abi_ver < 1) {
		/* The driver is using an old ABI, so we'll set the interface
		 * down to avoid any conflicts due to same MAC/IP
		 */
		res = set_if_down(slave_ifname, slave_flags.ifr_flags);
		if (res) {
			fprintf(stderr,
				"Slave '%s': Error: bring interface "
				"down failed\n",
				slave_ifname);
		}
	}

	/* set to default mtu */
	set_slave_mtu(slave_ifname, 1500);

	return res;
}

static int get_if_settings(char *ifname, struct dev_ifr ifra[])
{
	int i;
	int res = 0;

	for (i = 0; ifra[i].req_ifr; i++) {
		strncpy(ifra[i].req_ifr->ifr_name, ifname, IFNAMSIZ);
		res = ioctl(skfd, ifra[i].req_type, ifra[i].req_ifr);
		if (res < 0) {
			saved_errno = errno;
			v_print("Interface '%s': Error: %s failed: %s\n",
				ifname, ifra[i].req_name,
				strerror(saved_errno));

			return saved_errno;
		}
	}

	return 0;
}

static int get_slave_flags(char *slave_ifname)
{
	int res = 0;

	strncpy(slave_flags.ifr_name, slave_ifname, IFNAMSIZ);
	res = ioctl(skfd, SIOCGIFFLAGS, &slave_flags);
	if (res < 0) {
		saved_errno = errno;
		v_print("Slave '%s': Error: SIOCGIFFLAGS failed: %s\n",
			slave_ifname, strerror(saved_errno));
	} else {
		v_print("Slave %s: flags %04X.\n",
			slave_ifname, slave_flags.ifr_flags);
	}

	return res;
}

static int set_master_hwaddr(char *master_ifname, struct sockaddr *hwaddr)
{
	unsigned char *addr = (unsigned char *)hwaddr->sa_data;
	struct ifreq ifr;
	int res = 0;

	strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
	memcpy(&(ifr.ifr_hwaddr), hwaddr, sizeof(struct sockaddr));
	res = ioctl(skfd, SIOCSIFHWADDR, &ifr);
	if (res < 0) {
		saved_errno = errno;
		v_print("Master '%s': Error: SIOCSIFHWADDR failed: %s\n",
			master_ifname, strerror(saved_errno));
		return res;
	} else {
		v_print("Master '%s': hardware address set to "
			"%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x.\n",
			master_ifname, addr[0], addr[1], addr[2],
			addr[3], addr[4], addr[5]);
	}

	return res;
}

static int set_slave_hwaddr(char *slave_ifname, struct sockaddr *hwaddr)
{
	unsigned char *addr = (unsigned char *)hwaddr->sa_data;
	struct ifreq ifr;
	int res = 0;

	strncpy(ifr.ifr_name, slave_ifname, IFNAMSIZ);
	memcpy(&(ifr.ifr_hwaddr), hwaddr, sizeof(struct sockaddr));
	res = ioctl(skfd, SIOCSIFHWADDR, &ifr);
	if (res < 0) {
		saved_errno = errno;

		v_print("Slave '%s': Error: SIOCSIFHWADDR failed: %s\n",
			slave_ifname, strerror(saved_errno));

		if (saved_errno == EBUSY) {
			v_print("  The device is busy: it must be idle "
				"before running this command.\n");
		} else if (saved_errno == EOPNOTSUPP) {
			v_print("  The device does not support setting "
				"the MAC address.\n"
				"  Your kernel likely does not support slave "
				"devices.\n");
		} else if (saved_errno == EINVAL) {
			v_print("  The device's address type does not match "
				"the master's address type.\n");
		}
		return res;
	} else {
		v_print("Slave '%s': hardware address set to "
			"%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x.\n",
			slave_ifname, addr[0], addr[1], addr[2],
			addr[3], addr[4], addr[5]);
	}

	return res;
}

static int set_slave_mtu(char *slave_ifname, int mtu)
{
	struct ifreq ifr;
	int res = 0;

	ifr.ifr_mtu = mtu;
	strncpy(ifr.ifr_name, slave_ifname, IFNAMSIZ);

	res = ioctl(skfd, SIOCSIFMTU, &ifr);
	if (res < 0) {
		saved_errno = errno;
		v_print("Slave '%s': Error: SIOCSIFMTU failed: %s\n",
			slave_ifname, strerror(saved_errno));
	} else {
		v_print("Slave '%s': MTU set to %d.\n", slave_ifname, mtu);
	}

	return res;
}

static int set_if_flags(char *ifname, short flags)
{
	struct ifreq ifr;
	int res = 0;

	ifr.ifr_flags = flags;
	strncpy(ifr.ifr_name, ifname, IFNAMSIZ);

	res = ioctl(skfd, SIOCSIFFLAGS, &ifr);
	if (res < 0) {
		saved_errno = errno;
		v_print("Interface '%s': Error: SIOCSIFFLAGS failed: %s\n",
			ifname, strerror(saved_errno));
	} else {
		v_print("Interface '%s': flags set to %04X.\n", ifname, flags);
	}

	return res;
}

static int set_if_up(char *ifname, short flags)
{
	return set_if_flags(ifname, flags | IFF_UP);
}

static int set_if_down(char *ifname, short flags)
{
	return set_if_flags(ifname, flags & ~IFF_UP);
}

static int clear_if_addr(char *ifname)
{
	struct ifreq ifr;
	int res = 0;

	strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
	ifr.ifr_addr.sa_family = AF_INET;
	memset(ifr.ifr_addr.sa_data, 0, sizeof(ifr.ifr_addr.sa_data));

	res = ioctl(skfd, SIOCSIFADDR, &ifr);
	if (res < 0) {
		saved_errno = errno;
		v_print("Interface '%s': Error: SIOCSIFADDR failed: %s\n",
			ifname, strerror(saved_errno));
	} else {
		v_print("Interface '%s': address cleared\n", ifname);
	}

	return res;
}

static int set_if_addr(char *master_ifname, char *slave_ifname)
{
	struct ifreq ifr;
	int res;
	unsigned char *ipaddr;
	int i;
	struct {
		char *req_name;
		char *desc;
		int g_ioctl;
		int s_ioctl;
	} ifra[] = {
		{"IFADDR", "addr", SIOCGIFADDR, SIOCSIFADDR},
		{"DSTADDR", "destination addr", SIOCGIFDSTADDR, SIOCSIFDSTADDR},
		{"BRDADDR", "broadcast addr", SIOCGIFBRDADDR, SIOCSIFBRDADDR},
		{"NETMASK", "netmask", SIOCGIFNETMASK, SIOCSIFNETMASK},
		{NULL, NULL, 0, 0},
	};

	for (i = 0; ifra[i].req_name; i++) {
		strncpy(ifr.ifr_name, master_ifname, IFNAMSIZ);
		res = ioctl(skfd, ifra[i].g_ioctl, &ifr);
		if (res < 0) {
			int saved_errno = errno;

			v_print("Interface '%s': Error: SIOCG%s failed: %s\n",
				master_ifname, ifra[i].req_name,
				strerror(saved_errno));

			ifr.ifr_addr.sa_family = AF_INET;
			memset(ifr.ifr_addr.sa_data, 0,
			       sizeof(ifr.ifr_addr.sa_data));
		}

		strncpy(ifr.ifr_name, slave_ifname, IFNAMSIZ);
		res = ioctl(skfd, ifra[i].s_ioctl, &ifr);
		if (res < 0) {
			int saved_errno = errno;

			v_print("Interface '%s': Error: SIOCS%s failed: %s\n",
				slave_ifname, ifra[i].req_name,
				strerror(saved_errno));

		}

		ipaddr = ifr.ifr_addr.sa_data;
		v_print("Interface '%s': set IP %s to %d.%d.%d.%d\n",
			slave_ifname, ifra[i].desc,
			ipaddr[0], ipaddr[1], ipaddr[2], ipaddr[3]);
	}

	return 0;
}

/*
 * Local variables:
 *  version-control: t
 *  kept-new-versions: 5
 *  c-indent-level: 4
 *  c-basic-offset: 4
 *  tab-width: 4
 *  compile-command: "gcc -Wall -Wstrict-prototypes -O -I/usr/src/linux/include ifenslave.c -o ifenslave"
 * End:
 */