/* vi: set sw=4 ts=4: */
/*
 * ether-wake.c - Send a magic packet to wake up sleeping machines.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Author:      Donald Becker, http://www.scyld.com/"; http://www.scyld.com/wakeonlan.html
 * Busybox port: Christian Volkmann <haveaniceday@online.de>
 *               Used version of ether-wake.c: v1.09 11/12/2003 Donald Becker, http://www.scyld.com/";
 */

/* full usage according Donald Becker
 * usage: ether-wake [-i <ifname>] [-p aa:bb:cc:dd[:ee:ff]] 00:11:22:33:44:55\n"
 *
 *      This program generates and transmits a Wake-On-LAN (WOL)\n"
 *      \"Magic Packet\", used for restarting machines that have been\n"
 *      soft-powered-down (ACPI D3-warm state).\n"
 *      It currently generates the standard AMD Magic Packet format, with\n"
 *      an optional password appended.\n"
 *
 *      The single required parameter is the Ethernet MAC (station) address\n"
 *      of the machine to wake or a host ID with known NSS 'ethers' entry.\n"
 *      The MAC address may be found with the 'arp' program while the target\n"
 *      machine is awake.\n"
 *
 *      Options:\n"
 *              -b      Send wake-up packet to the broadcast address.\n"
 *              -D      Increase the debug level.\n"
 *              -i ifname       Use interface IFNAME instead of the default 'eth0'.\n"
 *              -p <pw>         Append the four or six byte password PW to the packet.\n"
 *                                      A password is only required for a few adapter types.\n"
 *                                      The password may be specified in ethernet hex format\n"
 *                                      or dotted decimal (Internet address)\n"
 *              -p 00:22:44:66:88:aa\n"
 *              -p 192.168.1.1\n";
 *
 *
 *      This program generates and transmits a Wake-On-LAN (WOL) "Magic Packet",
 *      used for restarting machines that have been soft-powered-down
 *      (ACPI D3-warm state).  It currently generates the standard AMD Magic Packet
 *      format, with an optional password appended.
 *
 *      This software may be used and distributed according to the terms
 *      of the GNU Public License, incorporated herein by reference.
 *      Contact the author for use under other terms.
 *
 *      This source file was originally part of the network tricks package, and
 *      is now distributed to support the Scyld Beowulf system.
 *      Copyright 1999-2003 Donald Becker and Scyld Computing Corporation.
 *
 *      The author may be reached as becker@scyld, or C/O
 *      Scyld Computing Corporation
 *      914 Bay Ridge Road, Suite 220
 *      Annapolis MD 21403
 *
 *   Notes:
 *   On some systems dropping root capability allows the process to be
 *   dumped, traced or debugged.
 *   If someone traces this program, they get control of a raw socket.
 *   Linux handles this safely, but beware when porting this program.
 *
 *   An alternative to needing 'root' is using a UDP broadcast socket, however
 *   doing so only works with adapters configured for unicast+broadcast Rx
 *   filter.  That configuration consumes more power.
 */

//usage:#define ether_wake_trivial_usage
//usage:       "[-b] [-i IFACE] [-p aa:bb:cc:dd[:ee:ff]/a.b.c.d] MAC"
//usage:#define ether_wake_full_usage "\n\n"
//usage:       "Send a magic packet to wake up sleeping machines.\n"
//usage:       "MAC must be a station address (00:11:22:33:44:55) or\n"
//usage:       "a hostname with a known 'ethers' entry.\n"
//usage:     "\n        -b              Broadcast the packet"
//usage:     "\n        -i IFACE        Interface to use (default eth0)"
//usage:     "\n        -p PASSWORD     Append four or six byte PASSWORD to the packet"

#include "libbb.h"
#include <netpacket/packet.h>
#include <netinet/ether.h>
#include <linux/if.h>

/* Note: PF_INET, SOCK_DGRAM, IPPROTO_UDP would allow SIOCGIFHWADDR to
 * work as non-root, but we need SOCK_PACKET to specify the Ethernet
 * destination address.
 */
#ifdef PF_PACKET
# define whereto_t sockaddr_ll
# define make_socket() xsocket(PF_PACKET, SOCK_RAW, 0)
#else
# define whereto_t sockaddr
# define make_socket() xsocket(AF_INET, SOCK_PACKET, SOCK_PACKET)
#endif

#ifdef DEBUG
# define bb_debug_msg(fmt, args...) fprintf(stderr, fmt, ## args)
void bb_debug_dump_packet(unsigned char *outpack, int pktsize)
{
        int i;
        printf("packet dump:\n");
        for (i = 0; i < pktsize; ++i) {
                printf("%2.2x ", outpack[i]);
                if (i % 20 == 19) bb_putchar('\n');
        }
        printf("\n\n");
}
#else
# define bb_debug_msg(fmt, args...)             ((void)0)
# define bb_debug_dump_packet(outpack, pktsize) ((void)0)
#endif

/* Convert the host ID string to a MAC address.
 * The string may be a:
 *    Host name
 *    IP address string
 *    MAC address string
 */
static void get_dest_addr(const char *hostid, struct ether_addr *eaddr)
{
        struct ether_addr *eap;

        eap = ether_aton_r(hostid, eaddr);
        if (eap) {
                bb_debug_msg("The target station address is %s\n\n", ether_ntoa(eap));
#if !defined(__UCLIBC__) || UCLIBC_VERSION >= KERNEL_VERSION(0, 9, 30)
        } else if (ether_hostton(hostid, eaddr) == 0) {
                bb_debug_msg("Station address for hostname %s is %s\n\n", hostid, ether_ntoa(eaddr));
#endif
        } else {
                bb_show_usage();
        }
}

#define PKT_HEADER_SIZE (20 + 16*6)
static int fill_pkt_header(unsigned char *pkt, struct ether_addr *eaddr, int broadcast)
{
        int i;
        unsigned char *station_addr = eaddr->ether_addr_octet;

        memset(pkt, 0xff, 6);
        if (!broadcast)
                memcpy(pkt, station_addr, 6);
        pkt += 6;

        memcpy(pkt, station_addr, 6); /* 6 */
        pkt += 6;

        *pkt++ = 0x08; /* 12 */ /* Or 0x0806 for ARP, 0x8035 for RARP */
        *pkt++ = 0x42; /* 13 */

        memset(pkt, 0xff, 6); /* 14 */

        for (i = 0; i < 16; ++i) {
                pkt += 6;
                memcpy(pkt, station_addr, 6); /* 20,26,32,... */
        }

        return PKT_HEADER_SIZE; /* length of packet */
}

static int get_wol_pw(const char *ethoptarg, unsigned char *wol_passwd)
{
        unsigned passwd[6];
        int byte_cnt, i;

        /* handle MAC format */
        byte_cnt = sscanf(ethoptarg, "%2x:%2x:%2x:%2x:%2x:%2x",
                          &passwd[0], &passwd[1], &passwd[2],
                          &passwd[3], &passwd[4], &passwd[5]);
        /* handle IP format */
// FIXME: why < 4?? should it be < 6?
        if (byte_cnt < 4)
                byte_cnt = sscanf(ethoptarg, "%u.%u.%u.%u",
                                  &passwd[0], &passwd[1], &passwd[2], &passwd[3]);
        if (byte_cnt < 4) {
                bb_error_msg("can't read Wake-On-LAN pass");
                return 0;
        }
// TODO: check invalid numbers >255??
        for (i = 0; i < byte_cnt; ++i)
                wol_passwd[i] = passwd[i];

        bb_debug_msg("password: %2.2x %2.2x %2.2x %2.2x (%d)\n\n",
                     wol_passwd[0], wol_passwd[1], wol_passwd[2], wol_passwd[3],
                     byte_cnt);

        return byte_cnt;
}

int ether_wake_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int ether_wake_main(int argc UNUSED_PARAM, char **argv)
{
        const char *ifname = "eth0";
        char *pass;
        unsigned flags;
        unsigned char wol_passwd[6];
        int wol_passwd_sz = 0;
        int s;  /* Raw socket */
        int pktsize;
        unsigned char outpack[PKT_HEADER_SIZE + 6 /* max passwd size */ + 16 /* paranoia */];

        struct ether_addr eaddr;
        struct whereto_t whereto;  /* who to wake up */

        /* handle misc user options */
        opt_complementary = "=1";
        flags = getopt32(argv, "bi:p:", &ifname, &pass);
        if (flags & 4) /* -p */
                wol_passwd_sz = get_wol_pw(pass, wol_passwd);
        flags &= 1; /* we further interested only in -b [bcast] flag */

        /* create the raw socket */
        s = make_socket();

        /* now that we have a raw socket we can drop root */
        /* xsetuid(getuid()); - but save on code size... */

        /* look up the dest mac address */
        get_dest_addr(argv[optind], &eaddr);

        /* fill out the header of the packet */
        pktsize = fill_pkt_header(outpack, &eaddr, flags /* & 1 OPT_BROADCAST */);

        bb_debug_dump_packet(outpack, pktsize);

        /* Fill in the source address, if possible. */
#ifdef __linux__
        {
                struct ifreq if_hwaddr;

                strncpy_IFNAMSIZ(if_hwaddr.ifr_name, ifname);
                ioctl_or_perror_and_die(s, SIOCGIFHWADDR, &if_hwaddr, "SIOCGIFHWADDR on %s failed", ifname);

                memcpy(outpack+6, if_hwaddr.ifr_hwaddr.sa_data, 6);

# ifdef DEBUG
                {
                        unsigned char *hwaddr = if_hwaddr.ifr_hwaddr.sa_data;
                        printf("The hardware address (SIOCGIFHWADDR) of %s is type %d  "
                                "%2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x\n\n", ifname,
                                if_hwaddr.ifr_hwaddr.sa_family, hwaddr[0], hwaddr[1],
                                hwaddr[2], hwaddr[3], hwaddr[4], hwaddr[5]);
                }
# endif
        }
#endif /* __linux__ */

        bb_debug_dump_packet(outpack, pktsize);

        /* append the password if specified */
        if (wol_passwd_sz > 0) {
                memcpy(outpack+pktsize, wol_passwd, wol_passwd_sz);
                pktsize += wol_passwd_sz;
        }

        bb_debug_dump_packet(outpack, pktsize);

        /* This is necessary for broadcasts to work */
        if (flags /* & 1 OPT_BROADCAST */) {
                if (setsockopt_broadcast(s) != 0)
                        bb_perror_msg("SO_BROADCAST");
        }

#if defined(PF_PACKET)
        {
                struct ifreq ifr;
                strncpy_IFNAMSIZ(ifr.ifr_name, ifname);
                xioctl(s, SIOCGIFINDEX, &ifr);
                memset(&whereto, 0, sizeof(whereto));
                whereto.sll_family = AF_PACKET;
                whereto.sll_ifindex = ifr.ifr_ifindex;
                /* The manual page incorrectly claims the address must be filled.
                   We do so because the code may change to match the docs. */
                whereto.sll_halen = ETH_ALEN;
                memcpy(whereto.sll_addr, outpack, ETH_ALEN);
        }
#else
        whereto.sa_family = 0;
        strcpy(whereto.sa_data, ifname);
#endif
        xsendto(s, outpack, pktsize, (struct sockaddr *)&whereto, sizeof(whereto));
        if (ENABLE_FEATURE_CLEAN_UP)
                close(s);
        return EXIT_SUCCESS;
}