/*      $OpenBSD: arp.c,v 1.89 2023/04/04 21:18:04 bluhm Exp $ */
/*      $NetBSD: arp.c,v 1.12 1995/04/24 13:25:18 cgd Exp $ */

/*
 * Copyright (c) 1984, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Sun Microsystems, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * arp - display, set, delete arp table entries and wake up hosts.
 */

#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/ioctl.h>
#include <net/bpf.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <arpa/inet.h>

#include <netdb.h>
#include <errno.h>
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <limits.h>
#include <ifaddrs.h>

void dump(void);
int delete(const char *);
void search(in_addr_t addr, void (*action)(struct sockaddr_dl *sdl,
        struct sockaddr_inarp *sin, struct rt_msghdr *rtm));
void print_entry(struct sockaddr_dl *sdl,
        struct sockaddr_inarp *sin, struct rt_msghdr *rtm);
void nuke_entry(struct sockaddr_dl *sdl,
        struct sockaddr_inarp *sin, struct rt_msghdr *rtm);
static char *ether_str(struct sockaddr_dl *);
int wake(const char *ether_addr, const char *iface);
int file(char *);
int get(const char *);
void getsocket(void);
int parse_host(const char *, struct in_addr *);
int rtget(struct sockaddr_inarp **, struct sockaddr_dl **);
int rtmsg(int);
int set(int, char **);
void usage(void);
static char *sec2str(time_t);

static pid_t pid;
static int replace;     /* replace entries when adding */
static int nflag;       /* no reverse dns lookups */
static int aflag;       /* do it for all entries */
static int rtsock = -1;
static int rdomain;

/* ROUNDUP() is nasty, but it is identical to what's in the kernel. */
#define ROUNDUP(a) \
        ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
#define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))

int
main(int argc, char *argv[])
{
        int              ch, func = 0, error = 0;
        const char      *errstr;

        pid = getpid();
        opterr = 0;
        rdomain = getrtable();
        while ((ch = getopt(argc, argv, "andsFfV:W")) != -1) {
                switch (ch) {
                case 'a':
                        aflag = 1;
                        break;
                case 'n':
                        nflag = 1;
                        break;
                case 'd':
                case 's':
                case 'f':
                case 'W':
                        if (func)
                                usage();
                        func = ch;
                        break;
                case 'F':
                        replace = 1;
                        break;
                case 'V':
                        rdomain = strtonum(optarg, 0, RT_TABLEID_MAX, &errstr);
                        if (errstr != NULL) {
                                warn("bad rdomain: %s", errstr);
                                usage();
                        }
                        break;
                default:
                        usage();
                        break;
                }
        }
        argc -= optind;
        argv += optind;

        switch (func) {
        case 0:
                if (aflag && argc == 0)
                        dump();
                else if (!aflag && argc == 1)
                        error = get(argv[0]);
                else
                        usage();
                break;
        case 's':
                if (argc < 2 || argc > 5)
                        usage();
                if (replace)
                        delete(argv[0]);
                error = set(argc, argv) ? 1 : 0;
                break;
        case 'd':
                if (aflag && argc == 0)
                        search(0, nuke_entry);
                else if (!aflag && argc == 1)
                        error = delete(argv[0]);
                else
                        usage();
                break;
        case 'f':
                if (argc != 1)
                        usage();
                error = file(argv[0]);
                break;
        case 'W':
                if (aflag || nflag || replace || rdomain > 0)
                        usage();
                if (argc == 1)
                        error = wake(argv[0], NULL);
                else if (argc == 2)
                        error = wake(argv[0], argv[1]);
                else
                        usage();
                break;
        }
        return (error);
}

/*
 * Process a file to set standard arp entries
 */
int
file(char *name)
{
        char     line[100], arg[5][50], *args[5];
        int      i, retval;
        FILE    *fp;

        if ((fp = fopen(name, "r")) == NULL)
                err(1, "cannot open %s", name);
        args[0] = &arg[0][0];
        args[1] = &arg[1][0];
        args[2] = &arg[2][0];
        args[3] = &arg[3][0];
        args[4] = &arg[4][0];
        retval = 0;
        while (fgets(line, sizeof(line), fp) != NULL) {
                i = sscanf(line, "%49s %49s %49s %49s %49s", arg[0], arg[1],
                    arg[2], arg[3], arg[4]);
                if (i < 2) {
                        warnx("bad line: %s", line);
                        retval = 1;
                        continue;
                }
                if (replace)
                        delete(arg[0]);
                if (set(i, args))
                        retval = 1;
        }
        fclose(fp);
        return (retval);
}

void
getsocket(void)
{
        socklen_t len = sizeof(rdomain);

        if (rtsock >= 0)
                return;
        rtsock = socket(AF_ROUTE, SOCK_RAW, 0);
        if (rtsock == -1)
                err(1, "routing socket");
        if (setsockopt(rtsock, AF_ROUTE, ROUTE_TABLEFILTER, &rdomain, len) == -1)
                err(1, "ROUTE_TABLEFILTER");

        if (pledge("stdio dns", NULL) == -1)
                err(1, "pledge");
}

int
parse_host(const char *host, struct in_addr *in)
{
        struct addrinfo hints, *res;
        struct sockaddr_in *sin;
        int gai_error;

        bzero(&hints, sizeof(hints));
        hints.ai_family = AF_INET;
        if (nflag)
                hints.ai_flags = AI_NUMERICHOST;

        gai_error = getaddrinfo(host, NULL, &hints, &res);
        if (gai_error) {
                warnx("%s: %s", host, gai_strerror(gai_error));
                return 1;
        }

        sin = (struct sockaddr_in *)res->ai_addr;
        *in = sin->sin_addr;

        freeaddrinfo(res);
        return 0;
}

struct sockaddr_in      so_mask = { 8, 0, 0, { 0xffffffff } };
struct sockaddr_inarp   blank_sin = { sizeof(blank_sin), AF_INET }, sin_m;
struct sockaddr_dl      blank_sdl = { sizeof(blank_sdl), AF_LINK }, sdl_m;
struct sockaddr_dl      ifp_m = { sizeof(ifp_m), AF_LINK };
time_t                  expire_time;
int                     flags, export_only, doing_proxy, found_entry;
struct  {
        struct rt_msghdr        m_rtm;
        char                    m_space[512];
}       m_rtmsg;

/*
 * Set an individual arp entry
 */
int
set(int argc, char *argv[])
{
        struct sockaddr_inarp *sin;
        struct sockaddr_dl *sdl;
        struct rt_msghdr *rtm;
        const char *host = argv[0], *eaddr = argv[1];
        struct ether_addr *ea;

        sin = &sin_m;
        rtm = &(m_rtmsg.m_rtm);

        getsocket();
        argc -= 2;
        argv += 2;
        sdl_m = blank_sdl;              /* struct copy */
        sin_m = blank_sin;              /* struct copy */
        if (parse_host(host, &sin->sin_addr))
                return (1);
        ea = ether_aton(eaddr);
        if (ea == NULL)
                errx(1, "invalid ethernet address: %s", eaddr);
        memcpy(LLADDR(&sdl_m), ea, sizeof(*ea));
        sdl_m.sdl_alen = 6;
        expire_time = 0;
        doing_proxy = flags = export_only = 0;
        while (argc-- > 0) {
                if (strncmp(argv[0], "temp", 4) == 0) {
                        expire_time = time(NULL) + 20 * 60;
                        if (flags & RTF_PERMANENT_ARP) {
                                /* temp or permanent, not both */
                                usage();
                                return (0);
                        }
                } else if (strncmp(argv[0], "pub", 3) == 0) {
                        flags |= RTF_ANNOUNCE;
                        doing_proxy = SIN_PROXY;
                } else if (strncmp(argv[0], "permanent", 9) == 0) {
                        flags |= RTF_PERMANENT_ARP;
                        if (expire_time != 0) {
                                /* temp or permanent, not both */
                                usage();
                                return (0);
                        }
                }

                argv++;
        }

tryagain:
        if (rtget(&sin, &sdl)) {
                warn("%s", host);
                return (1);
        }

        if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
                if (sdl->sdl_family == AF_LINK &&
                    (rtm->rtm_flags & RTF_LLINFO) &&
                    !(rtm->rtm_flags & RTF_GATEWAY))
                        switch (sdl->sdl_type) {
                        case IFT_ETHER:
                        case IFT_FDDI:
                        case IFT_ISO88023:
                        case IFT_ISO88024:
                        case IFT_ISO88025:
                        case IFT_CARP:
                                goto overwrite;
                        }

                if (doing_proxy == 0) {
                        printf("set: can only proxy for %s\n", host);
                        return (1);
                }
                if (sin_m.sin_other & SIN_PROXY) {
                        printf("set: proxy entry exists for non 802 device\n");
                        return (1);
                }
                sin_m.sin_other = SIN_PROXY;
                export_only = 1;
                goto tryagain;
        }

overwrite:
        if (sdl->sdl_family != AF_LINK) {
                printf("cannot intuit interface index and type for %s\n", host);
                return (1);
        }
        sdl_m.sdl_type = sdl->sdl_type;
        sdl_m.sdl_index = sdl->sdl_index;
        return (rtmsg(RTM_ADD));
}

#define W_ADDR  36
#define W_LL    17
#define W_IF    7

/*
 * Display an individual arp entry
 */
int
get(const char *host)
{
        struct sockaddr_inarp *sin;

        sin = &sin_m;
        sin_m = blank_sin;              /* struct copy */
        if (parse_host(host, &sin->sin_addr))
                return (1);

        printf("%-*.*s %-*.*s %*.*s %-9.9s %5s\n",
            W_ADDR, W_ADDR, "Host", W_LL, W_LL, "Ethernet Address",
            W_IF, W_IF, "Netif", "Expire", "Flags");

        search(sin->sin_addr.s_addr, print_entry);
        if (found_entry == 0) {
                printf("%-*.*s no entry\n", W_ADDR, W_ADDR,
                    inet_ntoa(sin->sin_addr));
                return (1);
        }
        return (0);
}

/*
 * Delete an arp entry
 */
int
delete(const char *host)
{
        struct sockaddr_inarp *sin;
        struct rt_msghdr *rtm;
        struct sockaddr_dl *sdl;

        sin = &sin_m;
        rtm = &m_rtmsg.m_rtm;

        getsocket();
        sin_m = blank_sin;              /* struct copy */
        if (parse_host(host, &sin->sin_addr))
                return 1;
tryagain:
        if (rtget(&sin, &sdl)) {
                warn("%s", host);
                return 1;
        }
        if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
                if (sdl->sdl_family == AF_LINK && rtm->rtm_flags & RTF_LLINFO) {
                        if (rtm->rtm_flags & RTF_LOCAL)
                                return 0;
                        if ((rtm->rtm_flags & RTF_GATEWAY) == 0)
                                switch (sdl->sdl_type) {
                                case IFT_ETHER:
                                case IFT_FDDI:
                                case IFT_ISO88023:
                                case IFT_ISO88024:
                                case IFT_ISO88025:
                                case IFT_CARP:
                                        goto delete;
                                }
                }
        }

        if (sin_m.sin_other & SIN_PROXY) {
                warnx("delete: cannot locate %s", host);
                return 1;
        } else {
                sin_m.sin_other = SIN_PROXY;
                goto tryagain;
        }
delete:
        if (sdl->sdl_family != AF_LINK) {
                printf("cannot locate %s\n", host);
                return 1;
        }
        if (rtmsg(RTM_DELETE))
                return 1;
        printf("%s (%s) deleted\n", host, inet_ntoa(sin->sin_addr));
        return 0;
}

/*
 * Search the entire arp table, and do some action on matching entries.
 */
void
search(in_addr_t addr, void (*action)(struct sockaddr_dl *sdl,
    struct sockaddr_inarp *sin, struct rt_msghdr *rtm))
{
        int mib[7];
        size_t needed;
        char *lim, *buf = NULL, *next;
        struct rt_msghdr *rtm;
        struct sockaddr_inarp *sin;
        struct sockaddr_dl *sdl;

        mib[0] = CTL_NET;
        mib[1] = PF_ROUTE;
        mib[2] = 0;
        mib[3] = AF_INET;
        mib[4] = NET_RT_FLAGS;
        mib[5] = RTF_LLINFO;
        mib[6] = rdomain;
        while (1) {
                if (sysctl(mib, 7, NULL, &needed, NULL, 0) == -1)
                        err(1, "route-sysctl-estimate");
                if (needed == 0)
                        return;
                if ((buf = realloc(buf, needed)) == NULL)
                        err(1, "malloc");
                if (sysctl(mib, 7, buf, &needed, NULL, 0) == -1) {
                        if (errno == ENOMEM)
                                continue;
                        err(1, "actual retrieval of routing table");
                }
                lim = buf + needed;
                break;
        }
        for (next = buf; next < lim; next += rtm->rtm_msglen) {
                rtm = (struct rt_msghdr *)next;
                if (rtm->rtm_version != RTM_VERSION)
                        continue;
                sin = (struct sockaddr_inarp *)(next + rtm->rtm_hdrlen);
                sdl = (struct sockaddr_dl *)(sin + 1);
                if (addr) {
                        if (addr != sin->sin_addr.s_addr)
                                continue;
                        found_entry = 1;
                }
                (*action)(sdl, sin, rtm);
        }
        free(buf);
}

/*
 * Dump the entire ARP table
 */
void
dump(void)
{
        printf("%-*.*s %-*.*s %*.*s %-9.9s %5s\n",
            W_ADDR, W_ADDR, "Host", W_LL, W_LL, "Ethernet Address",
            W_IF, W_IF, "Netif", "Expire", "Flags");

        search(0, print_entry);
}

/*
 * Display an arp entry
 */
void
print_entry(struct sockaddr_dl *sdl, struct sockaddr_inarp *sin,
    struct rt_msghdr *rtm)
{
        char ifix_buf[IFNAMSIZ], *ifname, *host;
        struct hostent *hp = NULL;
        int addrwidth, llwidth, ifwidth ;
        time_t now;

        now = time(NULL);

        if (nflag == 0)
                hp = gethostbyaddr((caddr_t)&(sin->sin_addr),
                    sizeof(sin->sin_addr), AF_INET);
        if (hp)
                host = hp->h_name;
        else
                host = inet_ntoa(sin->sin_addr);

        addrwidth = strlen(host);
        if (addrwidth < W_ADDR)
                addrwidth = W_ADDR;
        llwidth = strlen(ether_str(sdl));
        if (W_ADDR + W_LL - addrwidth > llwidth)
                llwidth = W_ADDR + W_LL - addrwidth;
        ifname = if_indextoname(sdl->sdl_index, ifix_buf);
        if (!ifname)
                ifname = "?";
        ifwidth = strlen(ifname);
        if (W_ADDR + W_LL + W_IF - addrwidth - llwidth > ifwidth)
                ifwidth = W_ADDR + W_LL + W_IF - addrwidth - llwidth;

        printf("%-*.*s %-*.*s %*.*s", addrwidth, addrwidth, host,
            llwidth, llwidth, ether_str(sdl), ifwidth, ifwidth, ifname);

        if (rtm->rtm_flags & (RTF_PERMANENT_ARP|RTF_LOCAL))
                printf(" %-9.9s", "permanent");
        else if (rtm->rtm_rmx.rmx_expire == 0)
                printf(" %-9.9s", "static");
        else if (rtm->rtm_rmx.rmx_expire > now)
                printf(" %-9.9s",
                    sec2str(rtm->rtm_rmx.rmx_expire - now));
        else
                printf(" %-9.9s", "expired");

        printf(" %s%s\n",
            (rtm->rtm_flags & RTF_LOCAL) ? "l" : "",
            (rtm->rtm_flags & RTF_ANNOUNCE) ? "p" : "");
}

/*
 * Nuke an arp entry
 */
void
nuke_entry(struct sockaddr_dl *sdl, struct sockaddr_inarp *sin,
    struct rt_msghdr *rtm)
{
        char ip[20];

        strlcpy(ip, inet_ntoa(sin->sin_addr), sizeof(ip));
        delete(ip);
}

static char *
ether_str(struct sockaddr_dl *sdl)
{
        static char hbuf[NI_MAXHOST];
        u_char *cp;

        if (sdl->sdl_alen) {
                cp = (u_char *)LLADDR(sdl);
                snprintf(hbuf, sizeof(hbuf), "%02x:%02x:%02x:%02x:%02x:%02x",
                    cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]);
        } else
                snprintf(hbuf, sizeof(hbuf), "(incomplete)");

        return(hbuf);
}

void
usage(void)
{
        fprintf(stderr, "usage: arp [-adn] [-V rdomain] hostname\n");
        fprintf(stderr, "       arp [-F] [-f file] [-V rdomain] "
            "-s hostname ether_addr\n"
            "           [temp | permanent] [pub]\n");
        fprintf(stderr, "       arp -W ether_addr [iface]\n");
        exit(1);
}

int
rtmsg(int cmd)
{
        static int seq;
        struct rt_msghdr *rtm;
        char *cp;
        int l;

        rtm = &m_rtmsg.m_rtm;
        cp = m_rtmsg.m_space;
        errno = 0;

        if (cmd == RTM_DELETE)
                goto doit;
        memset(&m_rtmsg, 0, sizeof(m_rtmsg));
        rtm->rtm_flags = flags;
        rtm->rtm_version = RTM_VERSION;
        rtm->rtm_hdrlen = sizeof(*rtm);
        rtm->rtm_tableid = rdomain;

        switch (cmd) {
        default:
                errx(1, "internal wrong cmd");
        case RTM_ADD:
                rtm->rtm_addrs |= RTA_GATEWAY;
                rtm->rtm_rmx.rmx_expire = expire_time;
                rtm->rtm_inits = RTV_EXPIRE;
                rtm->rtm_flags |= (RTF_HOST | RTF_STATIC);
                sin_m.sin_other = 0;
                if (doing_proxy) {
                        if (export_only)
                                sin_m.sin_other = SIN_PROXY;
                        else {
                                rtm->rtm_addrs |= RTA_NETMASK;
                                rtm->rtm_flags &= ~RTF_HOST;
                        }
                }
                /* FALLTHROUGH */
        case RTM_GET:
                rtm->rtm_addrs |= (RTA_DST | RTA_IFP);
        }

#define NEXTADDR(w, s)                                                  \
        if (rtm->rtm_addrs & (w)) {                                     \
                memcpy(cp, &(s), sizeof(s));                            \
                ADVANCE(cp, (struct sockaddr *)&(s));                   \
        }

        NEXTADDR(RTA_DST, sin_m);
        NEXTADDR(RTA_GATEWAY, sdl_m);
        NEXTADDR(RTA_NETMASK, so_mask);
        NEXTADDR(RTA_IFP, ifp_m);

        rtm->rtm_msglen = cp - (char *)&m_rtmsg;
doit:
        l = rtm->rtm_msglen;
        rtm->rtm_seq = ++seq;
        rtm->rtm_type = cmd;
        if (write(rtsock, (char *)&m_rtmsg, l) == -1)
                if (errno != ESRCH || cmd != RTM_DELETE) {
                        warn("writing to routing socket");
                        return (-1);
                }

        do {
                l = read(rtsock, (char *)&m_rtmsg, sizeof(m_rtmsg));
        } while (l > 0 && (rtm->rtm_version != RTM_VERSION ||
            rtm->rtm_seq != seq || rtm->rtm_pid != pid));

        if (l < 0)
                warn("read from routing socket");
        return (0);
}

int
rtget(struct sockaddr_inarp **sinp, struct sockaddr_dl **sdlp)
{
        struct rt_msghdr *rtm = &(m_rtmsg.m_rtm);
        struct sockaddr_inarp *sin = NULL;
        struct sockaddr_dl *sdl = NULL;
        struct sockaddr *sa;
        char *cp;
        unsigned int i;

        if (rtmsg(RTM_GET) < 0)
                return (1);

        if (rtm->rtm_addrs) {
                cp = ((char *)rtm + rtm->rtm_hdrlen);
                for (i = 1; i; i <<= 1) {
                        if (i & rtm->rtm_addrs) {
                                sa = (struct sockaddr *)cp;
                                switch (i) {
                                case RTA_DST:
                                        sin = (struct sockaddr_inarp *)sa;
                                        break;
                                case RTA_IFP:
                                        sdl = (struct sockaddr_dl *)sa;
                                        break;
                                default:
                                        break;
                                }
                                ADVANCE(cp, sa);
                        }
                }
        }

        if (sin == NULL || sdl == NULL)
                return (1);

        *sinp = sin;
        *sdlp = sdl;

        return (0);
}

static char *
sec2str(time_t total)
{
        static char result[256];
        int days, hours, mins, secs;
        int first = 1;
        char *p = result;
        char *ep = &result[sizeof(result)];
        int n;

        days = total / 3600 / 24;
        hours = (total / 3600) % 24;
        mins = (total / 60) % 60;
        secs = total % 60;

        if (days) {
                first = 0;
                n = snprintf(p, ep - p, "%dd", days);
                if (n < 0 || n >= ep - p)
                        return "?";
                p += n;
        }
        if (!first || hours) {
                first = 0;
                n = snprintf(p, ep - p, "%dh", hours);
                if (n < 0 || n >= ep - p)
                        return "?";
                p += n;
        }
        if (!first || mins) {
                first = 0;
                n = snprintf(p, ep - p, "%dm", mins);
                if (n < 0 || n >= ep - p)
                        return "?";
                p += n;
        }
        snprintf(p, ep - p, "%ds", secs);

        return(result);
}

/*
 * Copyright (c) 2011 Jasper Lievisse Adriaanse <jasper@openbsd.org>
 * Copyright (C) 2006,2007,2008,2009 Marc Balmer <mbalmer@openbsd.org>
 * Copyright (C) 2000 Eugene M. Kim.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Author's name may not be used endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

int     do_wakeup(const char *, const char *, int);
int     bind_if_to_bpf(const char *, int);
int     get_ether(const char *, struct ether_addr *);
int     send_frame(int, const struct ether_addr *);

int
wake(const char *ether_addr, const char *iface)
{
        struct ifaddrs          *ifa, *ifap;
        char                    *pname = NULL;
        int                      bpf;

        if ((bpf = open("/dev/bpf", O_RDWR)) == -1)
                err(1, "Failed to bind to bpf");

        if (iface == NULL) {
                if (getifaddrs(&ifa) == -1)
                        errx(1, "Could not get interface addresses.");

                for (ifap = ifa; ifap != NULL; ifap = ifap->ifa_next){
                        if (pname && !strcmp(pname, ifap->ifa_name))
                                continue;
                        pname = ifap->ifa_name;

                        /*
                         * We're only interested in sending the WoL frame on
                         * certain interfaces. So skip the loopback interface,
                         * as well as point-to-point and down interfaces.
                         */
                        if ((ifap->ifa_flags & IFF_LOOPBACK) ||
                            (ifap->ifa_flags & IFF_POINTOPOINT) ||
                            (!(ifap->ifa_flags & IFF_UP)) ||
                            (!(ifap->ifa_flags & IFF_BROADCAST)))
                                continue;

                        do_wakeup(ether_addr, ifap->ifa_name, bpf);
                }
                freeifaddrs(ifa);
        } else {
                do_wakeup(ether_addr, iface, bpf);
        }

        (void)close(bpf);

        return 0;
}

int
do_wakeup(const char *eaddr, const char *iface, int bpf)
{
        struct ether_addr        macaddr;

        if (get_ether(eaddr, &macaddr) != 0)
                errx(1, "Invalid Ethernet address: %s", eaddr);
        if (bind_if_to_bpf(iface, bpf) != 0)
                errx(1, "Failed to bind %s to bpf.", iface);
        if (send_frame(bpf, &macaddr) != 0)
                errx(1, "Failed to send WoL frame on %s", iface);
        return 0;
}

int
bind_if_to_bpf(const char *ifname, int bpf)
{
        struct ifreq ifr;
        u_int dlt;

        if (strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)) >=
            sizeof(ifr.ifr_name))
                return -1;
        if (ioctl(bpf, BIOCSETIF, &ifr) == -1)
                return -1;
        if (ioctl(bpf, BIOCGDLT, &dlt) == -1)
                return -1;
        if (dlt != DLT_EN10MB)
                return -1;
        return 0;
}

int
get_ether(const char *text, struct ether_addr *addr)
{
        struct ether_addr *eaddr;

        eaddr = ether_aton(text);

        if (eaddr == NULL) {
                if (ether_hostton(text, addr))
                        return -1;
        } else {
                *addr = *eaddr;
                return 0;
        }

        return 0;
}

#define SYNC_LEN 6
#define DESTADDR_COUNT 16

int
send_frame(int bpf, const struct ether_addr *addr)
{
        struct {
                struct ether_header hdr;
                u_char sync[SYNC_LEN];
                u_char dest[ETHER_ADDR_LEN * DESTADDR_COUNT];
        } __packed pkt;
        u_char *p;
        int i;

        (void)memset(&pkt, 0, sizeof(pkt));
        (void)memset(&pkt.hdr.ether_dhost, 0xff, sizeof(pkt.hdr.ether_dhost));
        pkt.hdr.ether_type = htons(0);
        (void)memset(pkt.sync, 0xff, SYNC_LEN);
        for (p = pkt.dest, i = 0; i < DESTADDR_COUNT; p += ETHER_ADDR_LEN, i++)
                bcopy(addr->ether_addr_octet, p, ETHER_ADDR_LEN);
        if (write(bpf, &pkt, sizeof(pkt)) != sizeof(pkt))
                return (errno);
        return (0);
}