/*  
 *  This file is free software: you may copy, redistribute 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.  
 *  
 *  This file is distributed in the hope that it will be useful, but  
 *  WITHOUT ANY WARRANTY; without even the implied warranty of  
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  
 *  General Public License for more details.  
 *  
 *  You should have received a copy of the GNU General Public License  
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.  
 *  
 * This file incorporates work covered by the following copyright and  
 * permission notice:  
 *  

Copyright 2007, 2008 by Grégoire Henry, Julien Cristau and Juliusz Chroboczek
Copyright 2011, 2012 by Matthieu Boutier and Juliusz Chroboczek

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include <sys/time.h>
#include <sys/param.h>
#include <time.h>

#include "babeld.h"


#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>

#include <zebra.h>
#include "prefix.h"
#include "zclient.h"
#include "kernel.h"
#include "privs.h"
#include "command.h"
#include "vty.h"
#include "memory.h"
#include "thread.h"

#include "util.h"
#include "babel_interface.h"
#include "babel_zebra.h"


static int
kernel_route_v4(int add, const unsigned char *pref, unsigned short plen,
                const unsigned char *gate, int ifindex,
                unsigned int metric);
static int
kernel_route_v6(int add, const unsigned char *pref, unsigned short plen,
                const unsigned char *gate, int ifindex,
                unsigned int metric);

int
kernel_interface_operational(struct interface *interface)
{
    return if_is_operative(interface);
}

int
kernel_interface_mtu(struct interface *interface)
{
    return MIN(interface->mtu, interface->mtu6);
}

int
kernel_interface_wireless(struct interface *interface)
{
    return 0;
}

int
kernel_route(int operation, const unsigned char *pref, unsigned short plen,
             const unsigned char *gate, int ifindex, unsigned int metric,
             const unsigned char *newgate, int newifindex,
             unsigned int newmetric)
{
    int rc;
    int ipv4;

    /* Check that the protocol family is consistent. */
    if(plen >= 96 && v4mapped(pref)) {
        if(!v4mapped(gate)) {
            errno = EINVAL;
            return -1;
        }
        ipv4 = 1;
    } else {
        if(v4mapped(gate)) {
            errno = EINVAL;
            return -1;
        }
        ipv4 = 0;
    }

    switch (operation) {
        case ROUTE_ADD:
            return ipv4 ?
                   kernel_route_v4(1, pref, plen, gate, ifindex, metric):
                   kernel_route_v6(1, pref, plen, gate, ifindex, metric);
            break;
        case ROUTE_FLUSH:
            return ipv4 ?
                   kernel_route_v4(0, pref, plen, gate, ifindex, metric):
                   kernel_route_v6(0, pref, plen, gate, ifindex, metric);
            break;
        case ROUTE_MODIFY:
            if(newmetric == metric && memcmp(newgate, gate, 16) == 0 &&
               newifindex == ifindex)
                return 0;
            debugf(BABEL_DEBUG_ROUTE, "Modify route: delete old; add new.");
            rc = ipv4 ?
                kernel_route_v4(0, pref, plen, gate, ifindex, metric):
                kernel_route_v6(0, pref, plen, gate, ifindex, metric);

            if (rc < 0)
                return -1;

            rc = ipv4 ?
                kernel_route_v4(1, pref, plen, newgate, newifindex, newmetric):
                kernel_route_v6(1, pref, plen, newgate, newifindex, newmetric);

            return rc;
            break;
        default:
            zlog_err("this should never appens (false value - kernel_route)");
            assert(0);
            exit(1);
            break;
    }
}

static int
kernel_route_v4(int add,
                const unsigned char *pref, unsigned short plen,
                const unsigned char *gate, int ifindex, unsigned int metric)
{
    struct zapi_ipv4 api;               /* quagga's communication system */
    struct prefix_ipv4 quagga_prefix;   /* quagga's prefix */
    struct in_addr babel_prefix_addr;   /* babeld's prefix addr */
    struct in_addr nexthop;             /* next router to go */
    struct in_addr *nexthop_pointer = &nexthop; /* it's an array! */

    /* convert to be understandable by quagga */
    /* convert given addresses */
    uchar_to_inaddr(&babel_prefix_addr, pref);
    uchar_to_inaddr(&nexthop, gate);

    /* make prefix structure */
    memset (&quagga_prefix, 0, sizeof(quagga_prefix));
    quagga_prefix.family = AF_INET;
    IPV4_ADDR_COPY (&quagga_prefix.prefix, &babel_prefix_addr);
    quagga_prefix.prefixlen = plen - 96; /* our plen is for v4mapped's addr */
    apply_mask_ipv4(&quagga_prefix);

    api.type  = ZEBRA_ROUTE_BABEL;
    api.flags = 0;
    api.message = 0;
    api.safi = SAFI_UNICAST;

    /* Unlike the native Linux and BSD interfaces, Quagga doesn't like
       there to be both and IPv4 nexthop and an ifindex.  Omit the
       ifindex, and assume that the connected prefixes be set up
       correctly. */

    SET_FLAG(api.message, ZAPI_MESSAGE_NEXTHOP);
    api.ifindex_num = 0;
    if(metric >= KERNEL_INFINITY) {
        api.flags = ZEBRA_FLAG_BLACKHOLE;
        api.nexthop_num = 0;
    } else {
        api.nexthop_num = 1;
        api.nexthop = &nexthop_pointer;
        SET_FLAG(api.message, ZAPI_MESSAGE_METRIC);
        api.metric = metric;
    }

    debugf(BABEL_DEBUG_ROUTE, "%s route (ipv4) to zebra",
           add ? "adding" : "removing" );
    return zapi_ipv4_route (add ? ZEBRA_IPV4_ROUTE_ADD :
                                  ZEBRA_IPV4_ROUTE_DELETE,
                            zclient, &quagga_prefix, &api);
}

static int
kernel_route_v6(int add, const unsigned char *pref, unsigned short plen,
                const unsigned char *gate, int ifindex, unsigned int metric)
{
    unsigned int tmp_ifindex = ifindex; /* (for typing) */
    struct zapi_ipv6 api;               /* quagga's communication system */
    struct prefix_ipv6 quagga_prefix;   /* quagga's prefix */
    struct in6_addr babel_prefix_addr;  /* babeld's prefix addr */
    struct in6_addr nexthop;            /* next router to go */
    struct in6_addr *nexthop_pointer = &nexthop;

    /* convert to be understandable by quagga */
    /* convert given addresses */
    uchar_to_in6addr(&babel_prefix_addr, pref);
    uchar_to_in6addr(&nexthop, gate);

    /* make prefix structure */
    memset (&quagga_prefix, 0, sizeof(quagga_prefix));
    quagga_prefix.family = AF_INET6;
    IPV6_ADDR_COPY (&quagga_prefix.prefix, &babel_prefix_addr);
    quagga_prefix.prefixlen = plen;
    apply_mask_ipv6(&quagga_prefix);

    api.type  = ZEBRA_ROUTE_BABEL;
    api.flags = 0;
    api.message = 0;
    api.safi = SAFI_UNICAST;
    SET_FLAG(api.message, ZAPI_MESSAGE_NEXTHOP);
    if(metric >= KERNEL_INFINITY) {
        api.flags = ZEBRA_FLAG_BLACKHOLE;
        api.nexthop_num = 0;
        api.ifindex_num = 0;
    } else {
        api.nexthop_num = 1;
        api.nexthop = &nexthop_pointer;
        SET_FLAG(api.message, ZAPI_MESSAGE_IFINDEX);
        api.ifindex_num = 1;
        api.ifindex = &tmp_ifindex;
        SET_FLAG(api.message, ZAPI_MESSAGE_METRIC);
        api.metric = metric;
    }

    debugf(BABEL_DEBUG_ROUTE, "%s route (ipv6) to zebra",
           add ? "adding" : "removing" );
    return zapi_ipv6_route (add ? ZEBRA_IPV6_ROUTE_ADD :
                                  ZEBRA_IPV6_ROUTE_DELETE,
                            zclient, &quagga_prefix, &api);
}

int
if_eui64(char *ifname, int ifindex, unsigned char *eui)
{
    struct interface *ifp = if_lookup_by_index(ifindex);
    if (ifp == NULL) {
        return -1;
    }
#ifdef HAVE_STRUCT_SOCKADDR_DL
    u_char len = ifp->sdl.sdl_alen;
    char *tmp = ifp->sdl.sdl_data + ifp->sdl.sdl_nlen;
#else
    u_char len = (u_char) ifp->hw_addr_len;
    char *tmp = (void*) ifp->hw_addr;
#endif
    if (len == 8) {
        memcpy(eui, tmp, 8);
        eui[0] ^= 2;
    } else if (len == 6) {
        memcpy(eui,   tmp,   3);
        eui[3] = 0xFF;
        eui[4] = 0xFE;
        memcpy(eui+5, tmp+3, 3);
    } else {
        return -1;
    }
    return 0;
}

/* Like gettimeofday, but returns monotonic time.  If POSIX clocks are not
   available, falls back to gettimeofday but enforces monotonicity. */
int
gettime(struct timeval *tv)
{
    return quagga_gettime(QUAGGA_CLK_MONOTONIC, tv);
}

/* If /dev/urandom doesn't exist, this will fail with ENOENT, which the
   caller will deal with gracefully. */

int
read_random_bytes(void *buf, size_t len)
{
    int fd;
    int rc;

    fd = open("/dev/urandom", O_RDONLY);
    if(fd < 0) {
        rc = -1;
    } else {
        rc = read(fd, buf, len);
        if(rc < 0 || (unsigned) rc < len)
            rc = -1;
        close(fd);
    }
    return rc;
}