arp.c

Linux下网络相关工具源代码。

/*
 * arp                This file contains an implementation of the command
 *              that maintains the kernel's ARP cache.  It is derived
 *              from Berkeley UNIX arp(8), but cleaner and with sup-
 *              port for devices other than Ethernet.
 *
 * NET-TOOLS    A collection of programs that form the base set of the
 *              NET-3 Networking Distribution for the LINUX operating
 *              system.
 *
 * Version:     $Id: arp.c,v 1.12 1999/03/24 09:49:43 philip Exp $
 *
 * Maintainer:  Bernd 'eckes' Eckenfels, <[e-mail]>
 *
 * Author:      Fred N. van Kempen, <[e-mail]>
 *
 * Changes:
 *              (based on work from Fred N. van Kempen, <[e-mail]>)
 *              Alan Cox        :       modified for NET3
 *              Andrew Tridgell :       proxy arp netmasks
 *              Bernd Eckenfels :       -n option
 *              Bernd Eckenfels :       Use only /proc for display
 *       {1.60} Bernd Eckenfels :       new arpcode (-i) for 1.3.42 but works 
 *                                      with 1.2.x, too
 *       {1.61} Bernd Eckenfels :       more verbose messages
 *       {1.62} Bernd Eckenfels :       check -t for hw adresses and try to
 *                                      explain EINVAL (jeff)
 *970125 {1.63} Bernd Eckenfels :       -a print hardwarename instead of tiltle
 *970201 {1.64} Bernd Eckenfels :       net-features.h support
 *970203 {1.65} Bernd Eckenfels :       "#define" in "#if", 
 *                                      -H|-A additional to -t|-p
 *970214 {1.66} Bernd Eckenfels :       Fix optarg required for -H and -A
 *970412 {1.67} Bernd Eckenfels :       device=""; is default
 *970514 {1.68} Bernd Eckenfels :       -N and -D
 *970517 {1.69} Bernd Eckenfels :       usage() fixed
 *970622 {1.70} Bernd Eckenfels :       arp -d priv
 *970106 {1.80} Bernd Eckenfels :       new syntax without -D and with "dev <If>",
 *                                      ATF_MAGIC, ATF_DONTPUB support. 
 *                                      Typo fix (Debian Bug#5728 Giuliano Procida)
 *970803 {1.81} Bernd Eckenfels :       removed junk comment line 1
 *970925 {1.82} Bernd Eckenfels :       include fix for libc6
 *980213 (1.83) Phil Blundell:          set ATF_COM on new entries
 *980629 (1.84) Arnaldo Carvalho de Melo: gettext instead of catgets
 *990101 {1.85} Bernd Eckenfels		fixed usage and return codes
 *990105 (1.86) Phil Blundell:		don't ignore EINVAL in arp_set
 *
 *              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.
 */
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
/* #include <linux/netdevice.h> */
/* #include <linux/if_arp.h>    */
#include <net/if_arp.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <fcntl.h>
#include <string.h>
#include <getopt.h>
#include <unistd.h>
#include "net-support.h"
#include "pathnames.h"
#include "version.h"
#include "config.h"
#include "intl.h"
#include "util.h"

#define DFLT_AF	"inet"
#define DFLT_HW	"ether"

#define FEATURE_ARP
#include "lib/net-features.h"

char *Release = RELEASE, *Version = "arp 1.85 (1999-01-05)";

int opt_n = 0;			/* do not resolve addresses     */
int opt_N = 0;			/* use symbolic names           */
int opt_v = 0;			/* debugging output flag        */
int opt_D = 0;			/* HW-address is devicename     */
int opt_e = 0;			/* 0=BSD output, 1=new linux    */
int opt_a = 0;			/* all entries, substring match */
struct aftype *ap;		/* current address family       */
struct hwtype *hw;		/* current hardware type        */
int sockfd = 0;			/* active socket descriptor     */
int hw_set = 0;			/* flag if hw-type was set (-H) */
char device[16] = "";		/* current device               */
static void usage(void);

/* Delete an entry from the ARP cache. */
static int arp_del(char **args)
{
    char host[128];
    struct arpreq req;
    struct sockaddr sa;
    int flags = 0;
    int err;

    memset((char *) &req, 0, sizeof(req));

    /* Resolve the host name. */
    if (*args == NULL) {
	fprintf(stderr, _("arp: need host name\n"));
	return (-1);
    }
    safe_strncpy(host, *args, (sizeof host));
    if (ap->input(0, host, &sa) < 0) {
	ap->herror(host);
	return (-1);
    }
    /* If a host has more than one address, use the correct one! */
    memcpy((char *) &req.arp_pa, (char *) &sa, sizeof(struct sockaddr));

    if (hw_set)
	req.arp_ha.sa_family = hw->type;

    req.arp_flags = ATF_PERM;
    args++;
    while (*args != NULL) {
	if (opt_v)
	    fprintf(stderr, "args=%s\n", *args);
	if (!strcmp(*args, "pub")) {
	    flags |= 1;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "priv")) {
	    flags |= 2;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "temp")) {
	    req.arp_flags &= ~ATF_PERM;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "trail")) {
	    req.arp_flags |= ATF_USETRAILERS;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "dontpub")) {
#ifdef HAVE_ATF_DONTPUB
	    req.arp_flags |= ATF_DONTPUB;
#else
	    ENOSUPP("arp", "ATF_DONTPUB");
#endif
	    args++;
	    continue;
	}
	if (!strcmp(*args, "auto")) {
#ifdef HAVE_ATF_MAGIC
	    req.arp_flags |= ATF_MAGIC;
#else
	    ENOSUPP("arp", "ATF_MAGIC");
#endif
	    args++;
	    continue;
	}
	if (!strcmp(*args, "dev")) {
	    if (*++args == NULL)
		usage();
	    safe_strncpy(device, *args, sizeof(device));
	    args++;
	    continue;
	}
	if (!strcmp(*args, "netmask")) {
	    if (*++args == NULL)
		usage();
	    if (strcmp(*args, "255.255.255.255") != 0) {
		strcpy(host, *args);
		if (ap->input(0, host, &sa) < 0) {
		    ap->herror(host);
		    return (-1);
		}
		memcpy((char *) &req.arp_netmask, (char *) &sa,
		       sizeof(struct sockaddr));
		req.arp_flags |= ATF_NETMASK;
	    }
	    args++;
	    continue;
	}
	usage();
    }
    if (flags == 0)
	flags = 3;

    strcpy(req.arp_dev, device);

    err = -1;

    /* Call the kernel. */
    if (flags & 2) {
	if (opt_v)
	    fprintf(stderr, "arp: SIOCDARP(nopub)\n");
	if ((err = ioctl(sockfd, SIOCDARP, &req) < 0)) {
	    if (errno == ENXIO) {
		if (flags & 1)
		    goto nopub;
		printf(_("No ARP entry for %s\n"), host);
		return (-1);
	    }
	    perror("SIOCDARP(priv)");
	    return (-1);
	}
    }
    if ((flags & 1) && (err)) {
      nopub:
	req.arp_flags |= ATF_PUBL;
	if (opt_v)
	    fprintf(stderr, "arp: SIOCDARP(pub)\n");
	if (ioctl(sockfd, SIOCDARP, &req) < 0) {
	    if (errno == ENXIO) {
		printf(_("No ARP entry for %s\n"), host);
		return (-1);
	    }
	    perror("SIOCDARP(pub)");
	    return (-1);
	}
    }
    return (0);
}

/* Get the hardware address to a specified interface name */
static int arp_getdevhw(char *ifname, struct sockaddr *sa, struct hwtype *hw)
{
    struct ifreq ifr;
    struct hwtype *xhw;

    strcpy(ifr.ifr_name, ifname);
    if (ioctl(sockfd, SIOCGIFHWADDR, &ifr) < 0) {
	fprintf(stderr, _("arp: cant get HW-Address for `%s': %s.\n"), ifname, strerror(errno));
	return (-1);
    }
    if (hw && (ifr.ifr_hwaddr.sa_family != hw->type)) {
	fprintf(stderr, _("arp: protocol type mismatch.\n"));
	return (-1);
    }
    memcpy((char *) sa, (char *) &(ifr.ifr_hwaddr), sizeof(struct sockaddr));

    if (opt_v) {
	if (!(xhw = get_hwntype(ifr.ifr_hwaddr.sa_family)) || (xhw->sprint == 0)) {
	    xhw = get_hwntype(-1);
	}
	fprintf(stderr, _("arp: device `%s' has HW address %s `%s'.\n"), ifname, xhw->name, xhw->sprint(&ifr.ifr_hwaddr));
    }
    return (0);
}

/* Set an entry in the ARP cache. */
static int arp_set(char **args)
{
    char host[128];
    struct arpreq req;
    struct sockaddr sa;
    int flags;

    memset((char *) &req, 0, sizeof(req));

    /* Resolve the host name. */
    if (*args == NULL) {
	fprintf(stderr, _("arp: need host name\n"));
	return (-1);
    }
    safe_strncpy(host, *args++, (sizeof host));
    if (ap->input(0, host, &sa) < 0) {
	ap->herror(host);
	return (-1);
    }
    /* If a host has more than one address, use the correct one! */
    memcpy((char *) &req.arp_pa, (char *) &sa, sizeof(struct sockaddr));

    /* Fetch the hardware address. */
    if (*args == NULL) {
	fprintf(stderr, _("arp: need hardware address\n"));
	return (-1);
    }
    if (opt_D) {
	if (arp_getdevhw(*args++, &req.arp_ha, hw_set ? hw : NULL) < 0)
	    return (-1);
    } else {
	if (hw->input(*args++, &req.arp_ha) < 0) {
	    fprintf(stderr, _("arp: invalid hardware address\n"));
	    return (-1);
	}
    }

    /* Check out any modifiers. */
    flags = ATF_PERM | ATF_COM;
    while (*args != NULL) {
	if (!strcmp(*args, "temp")) {
	    flags &= ~ATF_PERM;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "pub")) {
	    flags |= ATF_PUBL;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "priv")) {
	    flags &= ~ATF_PUBL;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "trail")) {
	    flags |= ATF_USETRAILERS;
	    args++;
	    continue;
	}
	if (!strcmp(*args, "dontpub")) {
#ifdef HAVE_ATF_DONTPUB
	    flags |= ATF_DONTPUB;
#else
	    ENOSUPP("arp", "ATF_DONTPUB");
#endif
	    args++;
	    continue;
	}
	if (!strcmp(*args, "auto")) {
#ifdef HAVE_ATF_MAGIC
	    flags |= ATF_MAGIC;
#else
	    ENOSUPP("arp", "ATF_MAGIC");
#endif
	    args++;
	    continue;
	}
	if (!strcmp(*args, "dev")) {
	    if (*++args == NULL)
		usage();
	    safe_strncpy(device, *args, sizeof(device));
	    args++;
	    continue;
	}
	if (!strcmp(*args, "netmask")) {
	    if (*++args == NULL)
		usage();
	    if (strcmp(*args, "255.255.255.255") != 0) {
		strcpy(host, *args);
		if (ap->input(0, host, &sa) < 0) {
		    ap->herror(host);
		    return (-1);
		}
		memcpy((char *) &req.arp_netmask, (char *) &sa,
		       sizeof(struct sockaddr));
		flags |= ATF_NETMASK;
	    }
	    args++;
	    continue;
	}
	usage();
    }

    /* Fill in the remainder of the request. */
    req.arp_flags = flags;

    strcpy(req.arp_dev, device);

    /* Call the kernel. */
    if (opt_v)
	fprintf(stderr, "arp: SIOCSARP()\n");
    if (ioctl(sockfd, SIOCSARP, &req) < 0) {
        perror("SIOCSARP");
	return (-1);
    }
    return (0);
}


/* Process an EtherFile */
static int arp_file(char *name)
{
    char buff[1024];
    char *sp, *args[32];
    int linenr, argc;
    FILE *fp;

    if ((fp = fopen(name, "r")) == NULL) {
	fprintf(stderr, _("arp: cannot open etherfile %s !\n"), name);
	return (-1);