networking/ifconfig.c - codeaurora/busybox - Gitiles

 /* ifconfig
  *
  * Similar to the standard Unix ifconfig, but with only the necessary
  * parts for AF_INET, and without any printing of if info (for now).
  *
  * Bjorn Wesen, Axis Communications AB
  *
  *
  * Authors of the original ifconfig was:
  *              Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  *
  * 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;  either  version 2 of the License, or  (at
  * your option) any later version.
  *
  * $Id: ifconfig.c,v 1.5 2001/03/08 22:57:00 mjn3 Exp $
  *
  */

 /*
  * Heavily modified by Manuel Novoa III       Mar 6, 2001
  *
  * From initial port to busybox, removed most of the redundancy by
  * converting to a table-driven approach.  Added several (optional)
  * args missing from initial port.
  *
  * Still missing:  media.
  */

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>   // strcmp and friends
 #include <ctype.h>    // isdigit and friends
 #include <stddef.h>				/* offsetof */
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/ioctl.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <net/if.h>
 #include <net/if_arp.h>
 #include <linux/if_ether.h>
 #include "busybox.h"

 #ifdef BB_FEATURE_IFCONFIG_SLIP
 #include <linux/if_slip.h>
 #endif

 /* I don't know if this is needed for busybox or not.  Anyone? */
 #define QUESTIONABLE_ALIAS_CASE


 /* Defines for glibc2.0 users. */
 #ifndef SIOCSIFTXQLEN
 #define SIOCSIFTXQLEN      0x8943
 #define SIOCGIFTXQLEN      0x8942
 #endif

 /* ifr_qlen is ifru_ivalue, but it isn't present in 2.0 kernel headers */
 #ifndef ifr_qlen
 #define ifr_qlen        ifr_ifru.ifru_mtu
 #endif

 #ifndef IFF_DYNAMIC
 #define IFF_DYNAMIC     0x8000  /* dialup device with changing addresses */
 #endif

 /*
  * Here are the bit masks for the "flags" member of struct options below.
  * N_ signifies no arg prefix; M_ signifies arg prefixed by '-'.
  * CLR clears the flag; SET sets the flag; ARG signifies (optional) arg.
  */
 #define N_CLR            0x01
 #define M_CLR            0x02
 #define N_SET            0x04
 #define M_SET            0x08
 #define N_ARG            0x10
 #define M_ARG            0x20

 #define M_MASK           (M_CLR | M_SET | M_ARG)
 #define N_MASK           (N_CLR | N_SET | N_ARG)
 #define SET_MASK         (N_SET | M_SET)
 #define CLR_MASK         (N_CLR | M_CLR)
 #define SET_CLR_MASK     (SET_MASK | CLR_MASK)
 #define ARG_MASK         (M_ARG | N_ARG)

 /*
  * Here are the bit masks for the "arg_flags" member of struct options below.
  */

 /*
  * cast type:
  *   00 int
  *   01 char *
  *   02 HOST_COPY in_ether
  *   03 HOST_COPY INET_resolve
  */
 #define A_CAST_TYPE      0x03
 /*
  * map type:
  *   00 not a map type (mem_start, io_addr, irq)
  *   04 memstart (unsigned long)
  *   08 io_addr  (unsigned short)
  *   0C irq      (unsigned char)
  */
 #define A_MAP_TYPE       0x0C
 #define A_ARG_REQ        0x10	/* Set if an arg is required. */
 #define A_NETMASK        0x20	/* Set if netmask (check for multiple sets). */
 #define A_SET_AFTER      0x40	/* Set a flag at the end. */
 #define A_COLON_CHK      0x80	/* Is this needed?  See below. */

 /*
  * These defines are for dealing with the A_CAST_TYPE field.
  */
 #define A_CAST_CHAR_PTR  0x01
 #define A_CAST_RESOLVE   0x01
 #define A_CAST_HOST_COPY 0x02
 #define A_CAST_HOST_COPY_IN_ETHER    A_CAST_HOST_COPY
 #define A_CAST_HOST_COPY_RESOLVE     (A_CAST_HOST_COPY | A_CAST_RESOLVE)

 /*
  * These defines are for dealing with the A_MAP_TYPE field.
  */
 #define A_MAP_ULONG      0x04	/* memstart */
 #define A_MAP_USHORT     0x08	/* io_addr */
 #define A_MAP_UCHAR      0x0C	/* irq */

 /*
  * Define the bit masks signifying which operations to perform for each arg.
  */

 #define ARG_METRIC       (A_ARG_REQ /*| A_CAST_INT*/)
 #define ARG_MTU          (A_ARG_REQ /*| A_CAST_INT*/)
 #define ARG_TXQUEUELEN   (A_ARG_REQ /*| A_CAST_INT*/)
 #define ARG_MEM_START    (A_ARG_REQ | A_MAP_ULONG)
 #define ARG_IO_ADDR      (A_ARG_REQ | A_MAP_USHORT)
 #define ARG_IRQ          (A_ARG_REQ | A_MAP_UCHAR)
 #define ARG_DSTADDR      (A_ARG_REQ | A_CAST_HOST_COPY_RESOLVE)
 #define ARG_NETMASK      (A_ARG_REQ | A_CAST_HOST_COPY_RESOLVE | A_NETMASK)
 #define ARG_BROADCAST    (A_ARG_REQ | A_CAST_HOST_COPY_RESOLVE | A_SET_AFTER)
 #define ARG_HW           (A_ARG_REQ | A_CAST_HOST_COPY_IN_ETHER)
 #define ARG_POINTOPOINT  (A_CAST_HOST_COPY_RESOLVE | A_SET_AFTER)
 #define ARG_KEEPALIVE    (A_ARG_REQ | A_CAST_CHAR_PTR)
 #define ARG_OUTFILL      (A_ARG_REQ | A_CAST_CHAR_PTR)
 #define ARG_HOSTNAME     (A_CAST_HOST_COPY_RESOLVE | A_SET_AFTER | A_COLON_CHK)


 /*
  * Set up the tables.  Warning!  They must have corresponding order!
  */

 struct arg1opt {
 	const char *name;
 	unsigned short selector;
 	unsigned short ifr_offset;
 };

 struct options {
 	const char *name;
 	const unsigned char flags;
 	const unsigned char arg_flags;
 	const unsigned short selector;
 };

 #define ifreq_offsetof(x)  offsetof(struct ifreq, x)

 static const struct arg1opt Arg1Opt[] = {
 	{"SIOCSIFMETRIC",  SIOCSIFMETRIC,  ifreq_offsetof(ifr_metric)},
 	{"SIOCSIFMTU",     SIOCSIFMTU,     ifreq_offsetof(ifr_mtu)},
 	{"SIOCSIFTXQLEN",  SIOCSIFTXQLEN,  ifreq_offsetof(ifr_qlen)},
 	{"SIOCSIFDSTADDR", SIOCSIFDSTADDR, ifreq_offsetof(ifr_dstaddr)},
 	{"SIOCSIFNETMASK", SIOCSIFNETMASK, ifreq_offsetof(ifr_netmask)},
 	{"SIOCSIFBRDADDR", SIOCSIFBRDADDR, ifreq_offsetof(ifr_broadaddr)},
 #ifdef BB_FEATURE_IFCONFIG_HW
 	{"SIOCSIFHWADDR",  SIOCSIFHWADDR,  ifreq_offsetof(ifr_hwaddr)},
 #endif
 	{"SIOCSIFDSTADDR", SIOCSIFDSTADDR, ifreq_offsetof(ifr_dstaddr)},
 #ifdef SIOCSKEEPALIVE
 	{"SIOCSKEEPALIVE", SIOCSKEEPALIVE, ifreq_offsetof(ifr_data)},
 #endif
 #ifdef SIOCSOUTFILL
 	{"SIOCSOUTFILL",   SIOCSOUTFILL,   ifreq_offsetof(ifr_data)},
 #endif
 #ifdef BB_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
 	{"SIOCSIFMAP",     SIOCSIFMAP,     ifreq_offsetof(ifr_map.mem_start)},
 	{"SIOCSIFMAP",     SIOCSIFMAP,     ifreq_offsetof(ifr_map.base_addr)},
 	{"SIOCSIFMAP",     SIOCSIFMAP,     ifreq_offsetof(ifr_map.irq)},
 #endif
 	/* Last entry if for unmatched (possibly hostname) arg. */
 	{"SIOCSIFADDR",    SIOCSIFADDR,    ifreq_offsetof(ifr_addr)},
 };

 static const struct options OptArray[] = {
 	{"metric",       N_ARG,         ARG_METRIC,      0},
     {"mtu",          N_ARG,         ARG_MTU,         0},
 	{"txqueuelen",   N_ARG,         ARG_TXQUEUELEN,  0},
 	{"dstaddr",      N_ARG,         ARG_DSTADDR,     0},
 	{"netmask",      N_ARG,         ARG_NETMASK,     0},
 	{"broadcast",    N_ARG | M_CLR, ARG_BROADCAST,   IFF_BROADCAST},
 #ifdef BB_FEATURE_IFCONFIG_HW
 	{"hw",           N_ARG,         ARG_HW,          0},
 #endif
 	{"pointopoint",  N_ARG | M_CLR, ARG_POINTOPOINT, IFF_POINTOPOINT},
 #ifdef SIOCSKEEPALIVE
 	{"keepalive",    N_ARG,         ARG_KEEPALIVE,   0},
 #endif
 #ifdef SIOCSOUTFILL
 	{"outfill",      N_ARG,         ARG_OUTFILL,     0},
 #endif
 #ifdef BB_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
 	{"mem_start",    N_ARG,         ARG_MEM_START,   0},
 	{"io_addr",      N_ARG,         ARG_IO_ADDR,     0},
 	{"irq",          N_ARG,         ARG_IRQ,         0},
 #endif
 	{"arp",          N_CLR | M_SET, 0,               IFF_NOARP},
 	{"trailers",     N_CLR | M_SET, 0,               IFF_NOTRAILERS},
 	{"promisc",      N_SET | M_CLR, 0,               IFF_PROMISC},
 	{"multicast",    N_SET | M_CLR, 0,               IFF_MULTICAST},
 	{"allmulti",     N_SET | M_CLR, 0,               IFF_ALLMULTI},
 	{"dynamic",      N_SET | M_CLR, 0,               IFF_DYNAMIC},
 	{"up",           N_SET        , 0,               (IFF_UP | IFF_RUNNING)},
 	{"down",         N_CLR        , 0,               IFF_UP},
 	{ NULL,          0,             ARG_HOSTNAME,    (IFF_UP | IFF_RUNNING)}
 };

 /*
  * A couple of prototypes.
  */

 #ifdef BB_FEATURE_IFCONFIG_HW
 static int in_ether(char *bufp, struct sockaddr *sap);
 #endif

 #ifdef BB_FEATURE_IFCONFIG_STATUS
 extern int display_interfaces(void);
 #endif

 /*
  * Our main function.
  */

 int ifconfig_main(int argc, char **argv)
 {
 	struct ifreq ifr;
 	struct sockaddr_in sai;
 #ifdef BB_FEATURE_IFCONFIG_HW
 	struct sockaddr sa;
 #endif
 	const struct arg1opt *a1op;
 	const struct options *op;
 	int sockfd;  /* socket fd we use to manipulate stuff with */
 	int goterr;
 	int selector;
 	char *p;
 	char host[128];
 	unsigned char mask;
 	unsigned char did_flags;

 	goterr = 0;
 	did_flags = 0;

 	if(argc < 2) {
 #ifdef BB_FEATURE_IFCONFIG_STATUS
 		return(display_interfaces());
 #else
 		show_usage();
 #endif
 	}

 	/* Create a channel to the NET kernel. */
 	if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 		perror("socket");
 		exit(1);
 	}

 	/* skip argv[0] */
 	argc--;
 	argv++;

 	/* get interface name */
 	safe_strncpy(ifr.ifr_name, *argv, IFNAMSIZ);

 	/* Process the remaining arguments. */
 	while (*++argv != (char *) NULL) {
 		p = *argv;
 		mask = N_MASK;
 		if (*p == '-') {		/* If the arg starts with '-'... */
 			++p;				/*    advance past it and */
 			mask = M_MASK;		/*    set the appropriate mask. */
 		}
 		for (op = OptArray ; op->name ; op++) {	/* Find table entry. */
 			if (!strcmp(p,op->name)) { /* If name matches... */
 				if ((mask &= op->flags)) { /* set the mask and go. */
 				    goto FOUND_ARG;;
 				}
 				/* If we get here, there was a valid arg with an */
 				/* invalid '-' prefix. */
 				++goterr;
 				goto LOOP;
 			}
 		}

 		/* We fell through, so treat as possible hostname. */
 		a1op = Arg1Opt + (sizeof(Arg1Opt) / sizeof(Arg1Opt[0])) - 1;
 		mask = op->arg_flags;
 		goto HOSTNAME;

 	FOUND_ARG:
 		if (mask & ARG_MASK) {
 			mask = op->arg_flags;
 			a1op = Arg1Opt + (op - OptArray);
 			if (mask & A_NETMASK & did_flags) {
 				show_usage();
 			}
 			if (*++argv == NULL) {
 				if (mask & A_ARG_REQ) {
 					show_usage();
 				} else {
 					--argv;
 					mask &= A_SET_AFTER; /* just for broadcast */
 				}
 			} else {			/* got an arg so process it */
 			HOSTNAME:
 				did_flags |= (mask & A_NETMASK);
 				if (mask & A_CAST_HOST_COPY) {
 #ifdef BB_FEATURE_IFCONFIG_HW
 					if (mask & A_CAST_RESOLVE) {
 #endif
 						safe_strncpy(host, *argv, (sizeof host));
 						sai.sin_family = AF_INET;
 						sai.sin_port = 0;
 						if (!strcmp(host, "default")) {
 							/* Default is special, meaning 0.0.0.0. */
 							sai.sin_addr.s_addr = INADDR_ANY;
 						} else if (inet_aton(host, &sai.sin_addr) == 0) {
 							/* It's not a dotted quad. */
 							++goterr;
 							continue;
 						}
 						p = (char *) &sai;
 #ifdef BB_FEATURE_IFCONFIG_HW
 					} else { /* A_CAST_HOST_COPY_IN_ETHER */
 						/* This is the "hw" arg case. */
 						if (strcmp("ether", *argv) || (*++argv == NULL)) {
 							show_usage();
 						}
 						safe_strncpy(host, *argv, (sizeof host));
 						if (in_ether(host, &sa)) {
 							fprintf(stderr, "invalid hw-addr %s\n", host);
 							++goterr;
 							continue;
 						}
 						p = (char *) &sa;
 					}
 #endif
 					memcpy((((char *)(&ifr)) + a1op->ifr_offset),
 						   p, sizeof(struct sockaddr));
 				} else {
 					unsigned int i = strtoul(*argv,NULL,0);
 					p = ((char *)(&ifr)) + a1op->ifr_offset;
 #ifdef BB_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
 					if (mask & A_MAP_TYPE) {
 						if (ioctl(sockfd, SIOCGIFMAP, &ifr) < 0) {
 							++goterr;
 							continue;
 						}
 						if ((mask & A_MAP_UCHAR) == A_MAP_UCHAR) {
 							*((unsigned char *) p) = i;
 						} else if (mask & A_MAP_USHORT) {
 							*((unsigned short *) p) = i;
 						} else {
 							*((unsigned long *) p) = i;
 						}
 					} else
 #endif
 					if (mask & A_CAST_CHAR_PTR) {
 						*((caddr_t *) p) = (caddr_t) i;
 					} else { /* A_CAST_INT */
 						*((int *) p) = i;
 					}
 				}

 				if (ioctl(sockfd, a1op->selector, &ifr) < 0) {
 					perror(a1op->name);
 					++goterr;
 					continue;
 				}

 #ifdef QUESTIONABLE_ALIAS_CASE
 				if (mask & A_COLON_CHK) {
 					/*
 					 * Don't do the set_flag() if the address is an alias with
 					 * a - at the end, since it's deleted already! - Roman
 					 *
 					 * Should really use regex.h here, not sure though how well
 					 * it'll go with the cross-platform support etc.
 					 */
 					char *ptr;
 					short int found_colon = 0;
 					for (ptr = ifr.ifr_name; *ptr; ptr++ ) {
 						if (*ptr == ':') {
 							found_colon++;
 						}
 					}

 					if (found_colon && *(ptr - 1) == '-') {
 						continue;
 					}
 				}
 #endif
 			}
 			if (!(mask & A_SET_AFTER)) {
 				continue;
 			}
 			mask = N_SET;
 		}

 		if (ioctl(sockfd, SIOCGIFFLAGS, &ifr) < 0) {
 			perror("SIOCGIFFLAGS");
 			++goterr;
 		} else {
 			selector = op->selector;
 			if (mask & SET_MASK) {
 				ifr.ifr_flags |= selector;
 			} else {
 				ifr.ifr_flags &= ~selector;
 			}
 			if (ioctl(sockfd, SIOCSIFFLAGS, &ifr) < 0) {
 				perror("SIOCSIFFLAGS");
 				++goterr;
 			}
 		}
 	LOOP:
 	} /* end of while-loop */

 	return goterr;
 }

 #ifdef BB_FEATURE_IFCONFIG_HW
 /* Input an Ethernet address and convert to binary. */
 static int
 in_ether(char *bufp, struct sockaddr *sap)
 {
 	unsigned char *ptr;
 	int i, j;
 	unsigned char val;
 	unsigned char c;

 	sap->sa_family = ARPHRD_ETHER;
 	ptr = sap->sa_data;

 	for (i = 0 ; i < ETH_ALEN ; i++) {
 		val = 0;

 		/* We might get a semicolon here - not required. */
 		if (i && (*bufp == ':')) {
 			bufp++;
 		}

 		for (j=0 ; j<2 ; j++) {
 			c = *bufp;
 			if (c >= '0' && c <= '9') {
 				c -= '0';
 			} else if (c >= 'a' && c <= 'f') {
 				c -= ('a' + 10);
 			} else if (c >= 'A' && c <= 'F') {
 				c -= ('A' + 10);
 			} else if (j && (c == ':' || c == 0)) {
 				break;
 			} else {
 				return -1;
 			}
 			++bufp;
 			val <<= 4;
 			val += c;
 		}
 		*ptr++ = val;
 	}

 	return (int) (*bufp);		/* Error if we don't end at end of string. */
 }
 #endif
	/* ifconfig
	*
	* Similar to the standard Unix ifconfig, but with only the necessary
	* parts for AF_INET, and without any printing of if info (for now).
	*
	* Bjorn Wesen, Axis Communications AB
	*
	*
	* Authors of the original ifconfig was:
	* Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
	*
	* 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; either version 2 of the License, or (at
	* your option) any later version.
	*
	* $Id: ifconfig.c,v 1.5 2001/03/08 22:57:00 mjn3 Exp $
	*
	*/

	/*
	* Heavily modified by Manuel Novoa III Mar 6, 2001
	*
	* From initial port to busybox, removed most of the redundancy by
	* converting to a table-driven approach. Added several (optional)
	* args missing from initial port.
	*
	* Still missing: media.
	*/

	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h> // strcmp and friends
	#include <ctype.h> // isdigit and friends
	#include <stddef.h> /* offsetof */
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <sys/ioctl.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <net/if.h>
	#include <net/if_arp.h>
	#include <linux/if_ether.h>
	#include "busybox.h"

	#ifdef BB_FEATURE_IFCONFIG_SLIP
	#include <linux/if_slip.h>
	#endif

	/* I don't know if this is needed for busybox or not. Anyone? */
	#define QUESTIONABLE_ALIAS_CASE


	/* Defines for glibc2.0 users. */
	#ifndef SIOCSIFTXQLEN
	#define SIOCSIFTXQLEN 0x8943
	#define SIOCGIFTXQLEN 0x8942
	#endif

	/* ifr_qlen is ifru_ivalue, but it isn't present in 2.0 kernel headers */
	#ifndef ifr_qlen
	#define ifr_qlen ifr_ifru.ifru_mtu
	#endif

	#ifndef IFF_DYNAMIC
	#define IFF_DYNAMIC 0x8000 /* dialup device with changing addresses */
	#endif

	/*
	* Here are the bit masks for the "flags" member of struct options below.
	* N_ signifies no arg prefix; M_ signifies arg prefixed by '-'.
	* CLR clears the flag; SET sets the flag; ARG signifies (optional) arg.
	*/
	#define N_CLR 0x01
	#define M_CLR 0x02
	#define N_SET 0x04
	#define M_SET 0x08
	#define N_ARG 0x10
	#define M_ARG 0x20

	#define M_MASK (M_CLR \| M_SET \| M_ARG)
	#define N_MASK (N_CLR \| N_SET \| N_ARG)
	#define SET_MASK (N_SET \| M_SET)
	#define CLR_MASK (N_CLR \| M_CLR)
	#define SET_CLR_MASK (SET_MASK \| CLR_MASK)
	#define ARG_MASK (M_ARG \| N_ARG)

	/*
	* Here are the bit masks for the "arg_flags" member of struct options below.
	*/

	/*
	* cast type:
	* 00 int
	* 01 char *
	* 02 HOST_COPY in_ether
	* 03 HOST_COPY INET_resolve
	*/
	#define A_CAST_TYPE 0x03
	/*
	* map type:
	* 00 not a map type (mem_start, io_addr, irq)
	* 04 memstart (unsigned long)
	* 08 io_addr (unsigned short)
	* 0C irq (unsigned char)
	*/
	#define A_MAP_TYPE 0x0C
	#define A_ARG_REQ 0x10 /* Set if an arg is required. */
	#define A_NETMASK 0x20 /* Set if netmask (check for multiple sets). */
	#define A_SET_AFTER 0x40 /* Set a flag at the end. */
	#define A_COLON_CHK 0x80 /* Is this needed? See below. */

	/*
	* These defines are for dealing with the A_CAST_TYPE field.
	*/
	#define A_CAST_CHAR_PTR 0x01
	#define A_CAST_RESOLVE 0x01
	#define A_CAST_HOST_COPY 0x02
	#define A_CAST_HOST_COPY_IN_ETHER A_CAST_HOST_COPY
	#define A_CAST_HOST_COPY_RESOLVE (A_CAST_HOST_COPY \| A_CAST_RESOLVE)

	/*
	* These defines are for dealing with the A_MAP_TYPE field.
	*/
	#define A_MAP_ULONG 0x04 /* memstart */
	#define A_MAP_USHORT 0x08 /* io_addr */
	#define A_MAP_UCHAR 0x0C /* irq */

	/*
	* Define the bit masks signifying which operations to perform for each arg.
	*/

	#define ARG_METRIC (A_ARG_REQ /\| A_CAST_INT/)
	#define ARG_MTU (A_ARG_REQ /\| A_CAST_INT/)
	#define ARG_TXQUEUELEN (A_ARG_REQ /\| A_CAST_INT/)
	#define ARG_MEM_START (A_ARG_REQ \| A_MAP_ULONG)
	#define ARG_IO_ADDR (A_ARG_REQ \| A_MAP_USHORT)
	#define ARG_IRQ (A_ARG_REQ \| A_MAP_UCHAR)
	#define ARG_DSTADDR (A_ARG_REQ \| A_CAST_HOST_COPY_RESOLVE)
	#define ARG_NETMASK (A_ARG_REQ \| A_CAST_HOST_COPY_RESOLVE \| A_NETMASK)
	#define ARG_BROADCAST (A_ARG_REQ \| A_CAST_HOST_COPY_RESOLVE \| A_SET_AFTER)
	#define ARG_HW (A_ARG_REQ \| A_CAST_HOST_COPY_IN_ETHER)
	#define ARG_POINTOPOINT (A_CAST_HOST_COPY_RESOLVE \| A_SET_AFTER)
	#define ARG_KEEPALIVE (A_ARG_REQ \| A_CAST_CHAR_PTR)
	#define ARG_OUTFILL (A_ARG_REQ \| A_CAST_CHAR_PTR)
	#define ARG_HOSTNAME (A_CAST_HOST_COPY_RESOLVE \| A_SET_AFTER \| A_COLON_CHK)


	/*
	* Set up the tables. Warning! They must have corresponding order!
	*/

	struct arg1opt {
	const char *name;
	unsigned short selector;
	unsigned short ifr_offset;
	};

	struct options {
	const char *name;
	const unsigned char flags;
	const unsigned char arg_flags;
	const unsigned short selector;
	};

	#define ifreq_offsetof(x) offsetof(struct ifreq, x)

	static const struct arg1opt Arg1Opt[] = {
	{"SIOCSIFMETRIC", SIOCSIFMETRIC, ifreq_offsetof(ifr_metric)},
	{"SIOCSIFMTU", SIOCSIFMTU, ifreq_offsetof(ifr_mtu)},
	{"SIOCSIFTXQLEN", SIOCSIFTXQLEN, ifreq_offsetof(ifr_qlen)},
	{"SIOCSIFDSTADDR", SIOCSIFDSTADDR, ifreq_offsetof(ifr_dstaddr)},
	{"SIOCSIFNETMASK", SIOCSIFNETMASK, ifreq_offsetof(ifr_netmask)},
	{"SIOCSIFBRDADDR", SIOCSIFBRDADDR, ifreq_offsetof(ifr_broadaddr)},
	#ifdef BB_FEATURE_IFCONFIG_HW
	{"SIOCSIFHWADDR", SIOCSIFHWADDR, ifreq_offsetof(ifr_hwaddr)},
	#endif
	{"SIOCSIFDSTADDR", SIOCSIFDSTADDR, ifreq_offsetof(ifr_dstaddr)},
	#ifdef SIOCSKEEPALIVE
	{"SIOCSKEEPALIVE", SIOCSKEEPALIVE, ifreq_offsetof(ifr_data)},
	#endif
	#ifdef SIOCSOUTFILL
	{"SIOCSOUTFILL", SIOCSOUTFILL, ifreq_offsetof(ifr_data)},
	#endif
	#ifdef BB_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
	{"SIOCSIFMAP", SIOCSIFMAP, ifreq_offsetof(ifr_map.mem_start)},
	{"SIOCSIFMAP", SIOCSIFMAP, ifreq_offsetof(ifr_map.base_addr)},
	{"SIOCSIFMAP", SIOCSIFMAP, ifreq_offsetof(ifr_map.irq)},
	#endif
	/* Last entry if for unmatched (possibly hostname) arg. */
	{"SIOCSIFADDR", SIOCSIFADDR, ifreq_offsetof(ifr_addr)},
	};

	static const struct options OptArray[] = {
	{"metric", N_ARG, ARG_METRIC, 0},
	{"mtu", N_ARG, ARG_MTU, 0},
	{"txqueuelen", N_ARG, ARG_TXQUEUELEN, 0},
	{"dstaddr", N_ARG, ARG_DSTADDR, 0},
	{"netmask", N_ARG, ARG_NETMASK, 0},
	{"broadcast", N_ARG \| M_CLR, ARG_BROADCAST, IFF_BROADCAST},
	#ifdef BB_FEATURE_IFCONFIG_HW
	{"hw", N_ARG, ARG_HW, 0},
	#endif
	{"pointopoint", N_ARG \| M_CLR, ARG_POINTOPOINT, IFF_POINTOPOINT},
	#ifdef SIOCSKEEPALIVE
	{"keepalive", N_ARG, ARG_KEEPALIVE, 0},
	#endif
	#ifdef SIOCSOUTFILL
	{"outfill", N_ARG, ARG_OUTFILL, 0},
	#endif
	#ifdef BB_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
	{"mem_start", N_ARG, ARG_MEM_START, 0},
	{"io_addr", N_ARG, ARG_IO_ADDR, 0},
	{"irq", N_ARG, ARG_IRQ, 0},
	#endif
	{"arp", N_CLR \| M_SET, 0, IFF_NOARP},
	{"trailers", N_CLR \| M_SET, 0, IFF_NOTRAILERS},
	{"promisc", N_SET \| M_CLR, 0, IFF_PROMISC},
	{"multicast", N_SET \| M_CLR, 0, IFF_MULTICAST},
	{"allmulti", N_SET \| M_CLR, 0, IFF_ALLMULTI},
	{"dynamic", N_SET \| M_CLR, 0, IFF_DYNAMIC},
	{"up", N_SET , 0, (IFF_UP \| IFF_RUNNING)},
	{"down", N_CLR , 0, IFF_UP},
	{ NULL, 0, ARG_HOSTNAME, (IFF_UP \| IFF_RUNNING)}
	};

	/*
	* A couple of prototypes.
	*/

	#ifdef BB_FEATURE_IFCONFIG_HW
	static int in_ether(char bufp, struct sockaddr sap);
	#endif

	#ifdef BB_FEATURE_IFCONFIG_STATUS
	extern int display_interfaces(void);
	#endif

	/*
	* Our main function.
	*/

	int ifconfig_main(int argc, char **argv)
	{
	struct ifreq ifr;
	struct sockaddr_in sai;
	#ifdef BB_FEATURE_IFCONFIG_HW
	struct sockaddr sa;
	#endif
	const struct arg1opt *a1op;
	const struct options *op;
	int sockfd; /* socket fd we use to manipulate stuff with */
	int goterr;
	int selector;
	char *p;
	char host[128];
	unsigned char mask;
	unsigned char did_flags;

	goterr = 0;
	did_flags = 0;

	if(argc < 2) {
	#ifdef BB_FEATURE_IFCONFIG_STATUS
	return(display_interfaces());
	#else
	show_usage();
	#endif
	}

	/* Create a channel to the NET kernel. */
	if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
	perror("socket");
	exit(1);
	}

	/* skip argv[0] */
	argc--;
	argv++;

	/* get interface name */
	safe_strncpy(ifr.ifr_name, *argv, IFNAMSIZ);

	/* Process the remaining arguments. */
	while (++argv != (char ) NULL) {
	p = *argv;
	mask = N_MASK;
	if (p == '-') { / If the arg starts with '-'... */
	++p; /* advance past it and */
	mask = M_MASK; /* set the appropriate mask. */
	}
	for (op = OptArray ; op->name ; op++) { /* Find table entry. */
	if (!strcmp(p,op->name)) { /* If name matches... */
	if ((mask &= op->flags)) { /* set the mask and go. */
	goto FOUND_ARG;;
	}
	/* If we get here, there was a valid arg with an */
	/* invalid '-' prefix. */
	++goterr;
	goto LOOP;
	}
	}

	/* We fell through, so treat as possible hostname. */
	a1op = Arg1Opt + (sizeof(Arg1Opt) / sizeof(Arg1Opt[0])) - 1;
	mask = op->arg_flags;
	goto HOSTNAME;

	FOUND_ARG:
	if (mask & ARG_MASK) {
	mask = op->arg_flags;
	a1op = Arg1Opt + (op - OptArray);
	if (mask & A_NETMASK & did_flags) {
	show_usage();
	}
	if (*++argv == NULL) {
	if (mask & A_ARG_REQ) {
	show_usage();
	} else {
	--argv;
	mask &= A_SET_AFTER; /* just for broadcast */
	}
	} else { /* got an arg so process it */
	HOSTNAME:
	did_flags \|= (mask & A_NETMASK);
	if (mask & A_CAST_HOST_COPY) {
	#ifdef BB_FEATURE_IFCONFIG_HW
	if (mask & A_CAST_RESOLVE) {
	#endif
	safe_strncpy(host, *argv, (sizeof host));
	sai.sin_family = AF_INET;
	sai.sin_port = 0;
	if (!strcmp(host, "default")) {
	/* Default is special, meaning 0.0.0.0. */
	sai.sin_addr.s_addr = INADDR_ANY;
	} else if (inet_aton(host, &sai.sin_addr) == 0) {
	/* It's not a dotted quad. */
	++goterr;
	continue;
	}
	p = (char *) &sai;
	#ifdef BB_FEATURE_IFCONFIG_HW
	} else { /* A_CAST_HOST_COPY_IN_ETHER */
	/* This is the "hw" arg case. */
	if (strcmp("ether", argv) \|\| (++argv == NULL)) {
	show_usage();
	}
	safe_strncpy(host, *argv, (sizeof host));
	if (in_ether(host, &sa)) {
	fprintf(stderr, "invalid hw-addr %s\n", host);
	++goterr;
	continue;
	}
	p = (char *) &sa;
	}
	#endif
	memcpy((((char *)(&ifr)) + a1op->ifr_offset),
	p, sizeof(struct sockaddr));
	} else {
	unsigned int i = strtoul(*argv,NULL,0);
	p = ((char *)(&ifr)) + a1op->ifr_offset;
	#ifdef BB_FEATURE_IFCONFIG_MEMSTART_IOADDR_IRQ
	if (mask & A_MAP_TYPE) {
	if (ioctl(sockfd, SIOCGIFMAP, &ifr) < 0) {
	++goterr;
	continue;
	}
	if ((mask & A_MAP_UCHAR) == A_MAP_UCHAR) {
	((unsigned char ) p) = i;
	} else if (mask & A_MAP_USHORT) {
	((unsigned short ) p) = i;
	} else {
	((unsigned long ) p) = i;
	}
	} else
	#endif
	if (mask & A_CAST_CHAR_PTR) {
	((caddr_t ) p) = (caddr_t) i;
	} else { /* A_CAST_INT */
	((int ) p) = i;
	}
	}

	if (ioctl(sockfd, a1op->selector, &ifr) < 0) {
	perror(a1op->name);
	++goterr;
	continue;
	}

	#ifdef QUESTIONABLE_ALIAS_CASE
	if (mask & A_COLON_CHK) {
	/*
	* Don't do the set_flag() if the address is an alias with
	* a - at the end, since it's deleted already! - Roman
	*
	* Should really use regex.h here, not sure though how well
	* it'll go with the cross-platform support etc.
	*/
	char *ptr;
	short int found_colon = 0;
	for (ptr = ifr.ifr_name; *ptr; ptr++ ) {
	if (*ptr == ':') {
	found_colon++;
	}
	}

	if (found_colon && *(ptr - 1) == '-') {
	continue;
	}
	}
	#endif
	}
	if (!(mask & A_SET_AFTER)) {
	continue;
	}
	mask = N_SET;
	}

	if (ioctl(sockfd, SIOCGIFFLAGS, &ifr) < 0) {
	perror("SIOCGIFFLAGS");
	++goterr;
	} else {
	selector = op->selector;
	if (mask & SET_MASK) {
	ifr.ifr_flags \|= selector;
	} else {
	ifr.ifr_flags &= ~selector;
	}
	if (ioctl(sockfd, SIOCSIFFLAGS, &ifr) < 0) {
	perror("SIOCSIFFLAGS");
	++goterr;
	}
	}
	LOOP:
	} /* end of while-loop */

	return goterr;
	}

	#ifdef BB_FEATURE_IFCONFIG_HW
	/* Input an Ethernet address and convert to binary. */
	static int
	in_ether(char bufp, struct sockaddr sap)
	{
	unsigned char *ptr;
	int i, j;
	unsigned char val;
	unsigned char c;

	sap->sa_family = ARPHRD_ETHER;
	ptr = sap->sa_data;

	for (i = 0 ; i < ETH_ALEN ; i++) {
	val = 0;

	/* We might get a semicolon here - not required. */
	if (i && (*bufp == ':')) {
	bufp++;
	}

	for (j=0 ; j<2 ; j++) {
	c = *bufp;
	if (c >= '0' && c <= '9') {
	c -= '0';
	} else if (c >= 'a' && c <= 'f') {
	c -= ('a' + 10);
	} else if (c >= 'A' && c <= 'F') {
	c -= ('A' + 10);
	} else if (j && (c == ':' \|\| c == 0)) {
	break;
	} else {
	return -1;
	}
	++bufp;
	val <<= 4;
	val += c;
	}
	*ptr++ = val;
	}

	return (int) (bufp); / Error if we don't end at end of string. */
	}
	#endif