usr/src/usr.sbin/arp/arp.c

#ifndef lint
static  char *sccsid = "@(#)arp.c       1.1 (Berkeley) %G%";
#endif

/*
 * arp - display, set, and delete arp table entries
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <netdb.h>
#include <nlist.h>
#include <net/if.h>
#include <netinet/if_ether.h>

extern int errno;

main(argc, argv)
        char **argv;
{
        if (argc >= 2 && strcmp(argv[1], "-a") == 0) {
                char *kernel = "/vmunix", *mem = "/dev/kmem";

                if (argc >= 3)
                        kernel = argv[2];
                if (argc >= 4)
                        mem = argv[3];
                dump(kernel, mem);
                exit(0);
        }
        if (argc == 2) {
                get(argv[1]);
                exit(0);
        }
        if (argc >= 4 && strcmp(argv[1], "-s") == 0) {
                set(argc-2, &argv[2]);
                exit(0);
        }
        if (argc == 3 && strcmp(argv[1], "-d") == 0) {
                delete(argv[2]);
                exit(0);
        }
        if (argc == 3 && strcmp(argv[1], "-f") == 0) {
                file(argv[2]);
                exit(0);
        }
        usage();
        exit(1);
}

/*
 * Process a file to set standard arp entries
 */
file(name)
        char *name;
{
        FILE *fp;
        int i;
        char line[100], arg[4][50], *args[4];

        if ((fp = fopen(name, "r")) == NULL) {
                fprintf(stderr, "arp: cannot open %s\n", name);
                exit(1);
        }
        args[0] = &arg[0][0];
        args[1] = &arg[1][0];
        args[2] = &arg[2][0];
        args[3] = &arg[3][0];
        while(fgets(line, 100, fp) != NULL) {
                i = sscanf(line, "%s %s %s %s", arg[0], arg[1], arg[2], arg[3]);
                if (i < 2) {
                        fprintf(stderr, "arp: bad line: %s\n", line);
                        continue;
                }
                set(i, args);
        }
        fclose(fp);
}

/*
 * Set an individual arp entry
 */
set(argc, argv)
        char **argv;
{
        struct arpreq ar;
        struct hostent *hp;
        struct sockaddr_in *sin;
        struct ether_addr *ea;
        int s;
        char *host = argv[0], *eaddr = argv[1];

        argc -= 2;
        argv += 2;
        hp = gethostbyname(host);
        if (hp == NULL) {
                fprintf(stderr, "arp: %s: unknown host\n", host);
                return (1);
        }
        bzero((caddr_t)&ar, sizeof ar);
        ar.arp_pa.sa_family = AF_INET;
        sin = (struct sockaddr_in *)&ar.arp_pa;
        sin->sin_addr = *(struct in_addr *)hp->h_addr;
        ea = (struct ether_addr *)ar.arp_ha.sa_data;
        if (ether_aton(eaddr, ea))
                return;
        ar.arp_flags = ATF_PERM;
        while(argc-- > 0) {
                if (strncmp(argv[0], "temp", 4) == 0)
                        ar.arp_flags &= ~ATF_PERM;
                if (strncmp(argv[0], "pub", 3) == 0)
                        ar.arp_flags |= ATF_PUBL;
                argv++;
        }

        s = socket(AF_INET, SOCK_DGRAM, 0);
        if (s < 0) {
                perror("arp: socket");
                exit(1);
        }
        if (ioctl(s, SIOCSARP, (caddr_t)&ar) < 0) {
                perror(host);
                exit(1);
        }
        close(s);
}


/*
 * Display an individual arp entry
 */
get(host)
        char *host;
{
        struct arpreq ar;
        struct hostent *hp;
        struct sockaddr_in *sin;
        struct ether_addr *ea;
        int s;

        hp = gethostbyname(host);
        if (hp == NULL) {
                fprintf(stderr, "arp: %s: unknown host\n", host);
                exit(1);
        }
        bzero((caddr_t)&ar, sizeof ar);
        ar.arp_pa.sa_family = AF_INET;
        sin = (struct sockaddr_in *)&ar.arp_pa;
        sin->sin_addr = *(struct in_addr *)hp->h_addr;
        s = socket(AF_INET, SOCK_DGRAM, 0);
        if (s < 0) {
                perror("arp: socket");
                exit(1);
        }
        if (ioctl(s, SIOCGARP, (caddr_t)&ar) < 0) {
                if (errno == ENXIO)
                        printf("%s (%s) -- no entry\n",
                            host, inet_ntoa(sin->sin_addr));
                else
                        perror("SIOCGARP");
                exit(1);
        }
        close(s);
        ea = (struct ether_addr *)ar.arp_ha.sa_data;
        printf("%s (%s) at ", host, inet_ntoa(sin->sin_addr));
        if (ar.arp_flags & ATF_COM)
                ether_print(ea);
        else
                printf("(incomplete)");
        if (!(ar.arp_flags & ATF_PERM)) printf(" temporary");
        if (ar.arp_flags & ATF_PUBL) printf(" published");
        printf("\n");
}

/*
 * Delete an arp entry
 */
delete(host)
        char *host;
{
        struct arpreq ar;
        struct hostent *hp;
        struct sockaddr_in *sin;
        int s;

        hp = gethostbyname(host);
        if (hp == NULL) {
                fprintf(stderr, "arp: %s: unknown host\n", host);
                exit(1);
        }
        bzero((caddr_t)&ar, sizeof ar);
        ar.arp_pa.sa_family = AF_INET;
        sin = (struct sockaddr_in *)&ar.arp_pa;
        sin->sin_addr = *(struct in_addr *)hp->h_addr;
        s = socket(AF_INET, SOCK_DGRAM, 0);
        if (s < 0) {
                perror("arp: socket");
                exit(1);
        }
        if (ioctl(s, SIOCDARP, (caddr_t)&ar) < 0) {
                if (errno == ENXIO)
                        printf("%s (%s) -- no entry\n",
                            host, inet_ntoa(sin->sin_addr));
                else
                        perror("SIOCDARP");
                exit(1);
        }
        close(s);
        printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr));
}

struct nlist nl[] = {
#define X_ARPTAB        0
        { "_arptab" },
#define X_ARPTAB_SIZE   1
        { "_arptab_size" },
        { "" },
};

/*
 * Dump the entire arp table
 */
dump(kernel, mem)
        char *kernel, *mem;
{
        int mf, arptab_size, sz;
        struct arptab *at;
        struct hostent *hp;
        char *host;

        nlist(kernel, nl);
        if(nl[X_ARPTAB_SIZE].n_type == 0) {
                fprintf(stderr, "arp: %s: bad namelist\n", kernel);
                exit(1);
        }
        mf = open(mem, 0);
        if(mf < 0) {
                fprintf(fprintf, "arp: cannot open %s\n", mem);
                exit(1);
        }
        lseek(mf, (long)nl[X_ARPTAB_SIZE].n_value, 0);
        read(mf, &arptab_size, sizeof arptab_size);
        if (arptab_size <=0 || arptab_size > 1000) {
                fprintf(stderr, "arp: %s: namelist wrong\n", kernel);
                exit(1);
        }
        sz = arptab_size * sizeof (struct arptab);
        at = (struct arptab *)malloc(sz);
        if (at == NULL) {
                fprintf(stderr, "arp: can't get memory for arptab\n");
                exit(1);
        }
        lseek(mf, (long)nl[X_ARPTAB].n_value, 0);
        if (read(mf, (char *)at, sz) != sz) {
                perror("arp: error reading arptab");
                exit(1);
        }
        close(mf);
        for (; arptab_size-- > 0; at++) {
                if (at->at_iaddr.s_addr == 0 || at->at_flags == 0)
                        continue;
                hp = gethostbyaddr((caddr_t)&at->at_iaddr, sizeof at->at_iaddr,
                        AF_INET);
                if (hp)
                        host = hp->h_name;
                else
                        host = "?";
                printf("%s (%s) at ", host, inet_ntoa(at->at_iaddr));
                if (at->at_flags & ATF_COM)
                        ether_print(&at->at_enaddr);
                else
                        printf("(incomplete)");
                if (!(at->at_flags & ATF_PERM)) printf(" temporary");
                if (at->at_flags & ATF_PUBL) printf(" published");
                printf("\n");
        }
}

ether_print(ea)
        struct ether_addr *ea;
{
        u_char *cp = &ea->ether_addr_octet[0];

        printf("%x:%x:%x:%x:%x:%x", cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]);
}

ether_aton(a, n)
        char *a;
        struct ether_addr *n;
{
        int i, o[6];

        i = sscanf(a, "%x:%x:%x:%x:%x:%x", &o[0], &o[1], &o[2],
                                           &o[3], &o[4], &o[5]);
        if (i != 6) {
                fprintf(stderr, "arp: invalid Ethernet address '%s'\n", a);
                return (1);
        }
        for (i=0; i<6; i++)
                n->ether_addr_octet[i] = o[i];
        return (0);
}

usage()
{
        printf("Usage: arp hostname\n");
        printf("       arp -a [/vmunix] [/dev/kmem]\n");
        printf("       arp -d hostname\n");
        printf("       arp -s hostname ether_addr [temp] [pub]\n");
        printf("       arp -f filename\n");
}