kernel_cygwin.c

/*
Copyright (c) 2007 by Grégoire Henry
Copyright (c) 2008, 2009 by Juliusz Chroboczek
Copyright (c) 2010 by Vincent Gross

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 <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>

#include <strings.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
#include <net/if.h>

#include "babeld.h"
#include "neighbour.h"
#include "kernel.h"
#include "util.h"

#include "cyginet.h"

/*
 * Some issues:
 *
 * 1. kernel_route
 *
 *    RTM_BLACKHOLE, gateway will be set as loopback, is it right?
 *
 * 2. IN6_LINKLOCAL_IFINDEX && SET_IN6_LINKLOCAL_IFINDEX
 *
 *    Do both of them work in the Windows?
 *
 * 3. kernel_interface_ipv4
 *
 *    ? interface name, ipv4, ifindex, Oh, they're mass.
 *    
 */

static int get_sdl(struct sockaddr_dl *sdl, char *ifname);

static const unsigned char v4prefix[16] =
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0, 0, 0, 0 };

int export_table = -1, import_table = -1;

int
if_eui64(char *ifname, int ifindex, unsigned char *eui)
{
    struct sockaddr_dl sdl;
    char *tmp = NULL;
    if (get_sdl(&sdl, ifname) < 0) {
        return -1;
    }
    tmp = sdl.sdl_data + sdl.sdl_nlen;
    if (sdl.sdl_alen == 8) {
        memcpy(eui, tmp, 8);
        eui[0] ^= 2;
    } else if (sdl.sdl_alen == 6) {
        memcpy(eui,   tmp,   3);
        eui[3] = 0xFF;
        eui[4] = 0xFE;
        memcpy(eui+5, tmp+3, 3);
    } else {
        return -1;
    }
    return 0;
}

/* fill sdl with the structure corresponding to ifname.
 Warning: make a syscall (and get all interfaces).
 return -1 if an error occurs, 0 otherwise. */
static int
get_sdl(struct sockaddr_dl *sdl, char *ifname)
{
    return cyginet_interface_sdl(sdl, ifname);
}

/* KAME said : "Following two macros are highly depending on KAME Release" */
#define	IN6_LINKLOCAL_IFINDEX(a)  ((a).s6_addr[2] << 8 | (a).s6_addr[3])
#define SET_IN6_LINKLOCAL_IFINDEX(a, i)         \
    do {                                        \
        (a).s6_addr[2] = ((i) >> 8) & 0xff;     \
        (a).s6_addr[3] = (i) & 0xff;            \
    } while (0)

static int old_forwarding = -1;
static int old_accept_redirects = -1;

static int ifindex_lo = -1;
static int if6index_lo = -1;

static int kernel_pipe_handles[2];

int
kernel_setup(int setup)
{
    int rc = 0;
    int forwarding = 1;
    int accept_redirects = 0;
    int reboot = 0;

    /* It enables ip6.forwarding and disable ip6.redirect. 
     *
     * Option 1:
     * 
     * IPV6CTL_FORWARDING (ip6.forwarding) Boolean: enable/disable
     * forward- ing of IPv6 packets.  Also, identify if the node is
     * acting as a router.  Defaults to off.
     *
     * ==> command line:
     *
     *     C:/> ipv6 ifc $If6Index forwards
     * 
     *     repeat this operation for all ipv6 interfaces
     *
     *     List all ipv6 interface by the command:
     *
     *         C:/> netsh interface ipv6 show interface
     *
     * ==> API: EnableRouter/DisableRouter (only for ipv4)
     *
     * ==> MSDN says in the registry
     *
     * HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
     *
     * Value Name: IPEnableRouter
     * Value type: REG_DWORD
     * Value Data: 1
     *
     * A value of 1 enables TCP/IP forwarding for all network
     * connections that are installed and used by this computer.
     * 
     * Refer to: http://support.microsoft.com/kb/315236/en-us
     *
     * Option 2:
     *
     * ICMPV6CTL_REDIRACCEPT
     * 
     * IPV6CTL_SENDREDIRECTS (ip6.redirect) Boolean: enable/disable
     * sending of ICMPv6 redirects in response to unforwardable IPv6
     * packets.  This option is ignored unless the node is routing
     * IPv6 packets, and should normally be enabled on all systems.
     * Defaults to on.
     *
     * ==> MSDN says in the registry
     *
     * HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
     * 
     * EnableICMPRedirect = 0
     *
     * Refer to:
     * 
     *     http://technet.microsoft.com/en-us/library/cc766102(v=ws.10).aspx
     *
     * After change them, need to reboot machine.
     *     
     * Notice:
     * 
     * MSDN says nothing about ipv6, it should use the following key
     * 
     * HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters
     *
     * Maybe later Window VISTA its corresponding APIs are
     * WSAEnumProtocols, WSCUpdateProvider.
     * 
     */
    
    if (setup) {
        int flags;
        if (0 != cyginet_startup())
            return -1;
        if ((rc = cyginet_set_ipv6_forwards(forwarding)) == -1) {
            fprintf(stderr, "Cannot enable IPv6 forwarding.\n");
            return -1;
        }
        old_forwarding = rc;
        reboot = (rc == forwarding) ? reboot : 1;

        if ((rc = cyginet_set_icmp6_redirect_accept(accept_redirects)) == -1) {
            fprintf(stderr, "Cannot disable ICMPv6 redirect.\n");
            if (reboot)
                cyginet_set_ipv6_forwards(old_forwarding);
            return -1;
        }    
        old_accept_redirects = rc;
        reboot = (rc == accept_redirects) ? reboot : 1;
        if (pipe(kernel_pipe_handles) == -1)
            return -1;
        if ((flags = fcntl(kernel_pipe_handles[0], F_GETFL, 0)) < 0)
            goto error;
        if (fcntl(kernel_pipe_handles[0], F_SETFL, flags | O_NONBLOCK) == -1)
            goto error;
    }
    else {
        if (-1 == (rc = cyginet_set_ipv6_forwards(old_forwarding)))
            return -1;
        reboot = (rc == forwarding) ? reboot : 1;
        if (-1 ==
            (rc = cyginet_set_icmp6_redirect_accept(old_accept_redirects)))
            return -1;
        reboot = (rc == accept_redirects) ? reboot : 1;
        close(kernel_pipe_handles[0]);
        close(kernel_pipe_handles[1]);     
        cyginet_cleanup();
    }

    if (reboot)
        fprintf(stderr,           
                "%s IPv6 forwarding and %s ICMPv6 redirect successfully.\n"
                "REBOOT NOW, so that these changes take effect.\n\n",
                forwarding ? "Enable" : "Disable",
                accept_redirects ? "enable" : "disable"
                );
    return 1;

 error: {
        if (reboot) {
            cyginet_set_ipv6_forwards(old_forwarding);
            cyginet_set_icmp6_redirect_accept(old_accept_redirects);
        }
        return -1;
    }
}

int
kernel_setup_socket(int setup)
{
    /* We use a pipe to notify route changed */
    if(setup) {
        if(kernel_socket < 0) {
            kernel_socket = kernel_pipe_handles[0];
            if (-1 ==
                cyginet_start_monitor_route_changes(kernel_pipe_handles[1])) {
                perror("start_monitor_route_changes");
                kernel_socket = -1;
                return -1;
            }
        }
    } else {
        cyginet_stop_monitor_route_changes();
        kernel_socket = -1;
    }
    return 1;
}

int
kernel_setup_interface(int setup, const char *ifname, int ifindex)
{
    return 1;
}

int
kernel_interface_operational(const char *ifname, int ifindex)
{
    int rc;
    int flags = link_detect ? (IFF_UP | IFF_RUNNING) : IFF_UP;
    
    rc = cyginet_interface_operational(ifname, ifindex);
    if (rc < 0)
        return -1;
    return ((rc & flags) == flags);
}

int
kernel_interface_ipv4(const char *ifname, int ifindex, unsigned char *addr_r)
{
    return cyginet_interface_ipv4(ifname, ifindex, addr_r);
}

int
kernel_interface_mtu(const char *ifname, int ifindex)
{
    return cyginet_interface_mtu(ifname, ifindex);
}

int
kernel_interface_wireless(const char *ifname, int ifindex)
{
    return cyginet_interface_wireless(ifname, ifindex);
}

int
kernel_interface_channel(const char *ifname, int ifindex)
{
    errno = ENOSYS;
    return -1;
}

/* 
 * RTF_REJECT 
 * 
 *   Instead of forwarding a packet like a normal route, routes with
 *   RTF_REJECT cause packets to be dropped and unreachable messages
 *   to be sent to the packet originators. This flag is only valid on
 *   routes pointing at the loopback interface.
 * 
 * RTF_BLACKHOLE 
 * 
 *   Like the RTF_REJECT flag, routes with RTF_BLACKHOLE cause packets
 *   to be dropped, but unreachable messages are not sent. This flag
 *   is only valid on routes pointing at the loopback interface.
 * 
 * Nullrouting on Windows
 * 
 *   Windows XP/Vista/7 does not support reject or blackhole arguments
 *   via route, thus an unused IP address (e.g. 192.168.0.205) must be
 *   used as the target gateway.
 *
 * RTF_GATEWAY: destination is a gateway
 *
 * RTF_HOST: host entry (net otherwise)
 *
 *   It means all the netmask bits are 1. 
 *
 * RTF_CLONING: generate new routes on use
 *
 *   No corresponding function in the Windows.
 *   
 */
int
kernel_route(int operation, const unsigned char *dest, unsigned short plen,
             const unsigned char *gate, int ifindex, unsigned int metric,
             const unsigned char *newgate, int newifindex,
             unsigned int newmetric)
{
    int rc, ipv4;
    struct sockaddr destination, gateway;
    int route_ifindex;
    int prefix_len;

    struct in6_addr local6 = {{IN6ADDR_LOOPBACK_INIT}};
    char local4[1][1][16] =
        {{{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x7f, 0x00, 0x00, 0x01 }}};

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

    if(operation == ROUTE_MODIFY && newmetric == metric && 
       memcmp(newgate, gate, 16) == 0 && newifindex == ifindex)
      return 0;

    if(operation == ROUTE_MODIFY) {
        /* Do not use ROUTE_MODIFY when changing to a neighbour.
           It is the only way to remove the "gateway" flag. */
        if(ipv4 && plen == 128 && memcmp(dest, newgate, 16) == 0) {
            kernel_route(ROUTE_FLUSH, dest, plen,
                         gate, ifindex, metric,
                         NULL, 0, 0);
            return kernel_route(ROUTE_ADD, dest, plen,
                                newgate, newifindex, newmetric,
                                NULL, 0, 0);
        } else {
            metric = newmetric;
            gate = newgate;
            ifindex = newifindex;
        }
    }

    kdebugf("kernel_route: %s %s/%d metric %d dev %d nexthop %s\n",
            operation == ROUTE_ADD ? "add" :
            operation == ROUTE_FLUSH ? "flush" : "change",
            format_address(dest), plen, metric, ifindex,
            format_address(gate));

    if(kernel_socket < 0) kernel_setup_socket(1);

    memset(&destination, 0, sizeof(destination));
    memset(&gateway, 0, sizeof(gateway));

    route_ifindex = ifindex;
    prefix_len = ipv4 ? plen - 96 : plen;

    if(metric == KERNEL_INFINITY) {
        /* RTF_BLACKHOLE; */
        /* ==> Set gateway to an unused ip address in the Windows */
        if(ipv4) {
            if (ifindex_lo < 0) {
                ifindex_lo = cyginet_loopback_index(AF_INET);
                if(ifindex_lo <= 0)
                    return -1;
            }
            route_ifindex = ifindex_lo;
        }
        else {
            if (if6index_lo < 0) {
                if6index_lo = cyginet_loopback_index(AF_INET6);
                if(if6index_lo <= 0)
                    return -1;
            }
            route_ifindex = if6index_lo;
        }
    }

#define PUSHADDR(dst, src)                                              \
    do { struct sockaddr_in *sin = (struct sockaddr_in*)(&(dst));       \
        sin->sin_family = AF_INET;                                      \
        memcpy(&sin->sin_addr, (src) + 12, 4);                          \
    } while (0)

#define PUSHADDR6(dst, src)                                             \
    do { struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)(&(dst));    \
        sin6->sin6_family = AF_INET6;                                   \
        memcpy(&sin6->sin6_addr, (src), 16);                            \
        if(IN6_IS_ADDR_LINKLOCAL (&sin6->sin6_addr))                    \
            SET_IN6_LINKLOCAL_IFINDEX (sin6->sin6_addr, ifindex);       \
    } while (0)
    
    if(ipv4) {

        PUSHADDR(destination, dest);
        if (metric == KERNEL_INFINITY)
            PUSHADDR(gateway, **local4);
        else 
            PUSHADDR(gateway, gate);

    } else {
        PUSHADDR6(destination, dest);
        if (metric == KERNEL_INFINITY)
            PUSHADDR6(gateway, &local6);
        else 
            PUSHADDR6(gateway, gate);
    }
#undef PUSHADDR
#undef PUSHADDR6

    switch(operation) {
    case ROUTE_FLUSH:
        rc = cyginet_delete_route_entry(&destination,
                                        prefix_len,
                                        &gateway,
                                        route_ifindex,
                                        metric
                                        );
        break;
    case ROUTE_ADD:
        rc = cyginet_add_route_entry(&destination,
                                     prefix_len,
                                     &gateway,
                                     route_ifindex,
                                     metric
                                     );
        break;
    case ROUTE_MODIFY:
        rc = cyginet_update_route_entry(&destination,
                                        prefix_len,
                                        &gateway,
                                        route_ifindex,
                                        metric
                                        );
        break;
    default:
        return -1;
    };

    /* Monitor thread will write data to kernel pipe when any change
       in the route table is happened. Here it's babeld itself to
       change the route table, so kernel pipe need to be clean. */
    int ch;
    while (read(kernel_pipe_handles[0], &ch, 1) > 0);
    return rc;
}

static void
print_kernel_route(int add, struct kernel_route *route)
{
    char ifname[IFNAMSIZ];

    if(!if_indextoname(route->ifindex, ifname))
      memcpy(ifname,"unk",4);

    fprintf(stderr,
            "%s kernel route: dest: %s gw: %s metric: %d if: %s(%d) \n",
            add == RTM_ADD ? "Add" :
            add == RTM_DELETE ? "Delete" : "Change",
            format_prefix(route->prefix, route->plen),
            format_address(route->gw),
            route->metric,
            ifname, route->ifindex
            );
}

static int
parse_kernel_route(struct kernel_route *route)
{
    struct sockaddr *sa;

    if(ifindex_lo < 0) {
        ifindex_lo = cyginet_loopback_index(AF_INET);
        if(ifindex_lo <= 0)
            return -1;
    }

    if(if6index_lo < 0) {
        if6index_lo = cyginet_loopback_index(AF_INET6);
        if(if6index_lo <= 0)
            return -1;
    }

    sa = (struct sockaddr *)route -> prefix;
    if(sa->sa_family == AF_INET6) {
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;
        if(IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)
             || IN6_IS_ADDR_MC_LINKLOCAL(&sin6->sin6_addr))
           return -1;
    } else if(sa->sa_family == AF_INET) {
        struct sockaddr_in *sin = (struct sockaddr_in *)sa;
#if defined(IN_LINKLOCAL)
        if(IN_LINKLOCAL(ntohl(sin->sin_addr.s_addr)))
            return -1;
#endif
        if(IN_MULTICAST(ntohl(sin->sin_addr.s_addr)))
            return -1;
        v4tov6(route->prefix, (unsigned char *)&sin->sin_addr);
    } else {
        return -1;
    }

    /* Gateway */
    sa = (struct sockaddr *)route -> gw;
    if(sa->sa_family == AF_INET6) {
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;
        if(IN6_IS_ADDR_LINKLOCAL (&sin6->sin6_addr)) {
            route->ifindex = IN6_LINKLOCAL_IFINDEX(sin6->sin6_addr);
            SET_IN6_LINKLOCAL_IFINDEX(sin6->sin6_addr, 0);
        }
    } else if(sa->sa_family == AF_INET) {
        struct sockaddr_in *sin = (struct sockaddr_in *)sa;
        v4tov6(route->gw, (unsigned char *)&sin->sin_addr);
    }

    if((sa->sa_family == AF_INET6) && (route->ifindex == if6index_lo))    
        return -1;
    if((sa->sa_family == AF_INET) && (route->ifindex == ifindex_lo))
        return -1;

    /* Netmask */
    if(v4mapped(route->prefix)) route->plen += 96;

    return 0;
}

int
kernel_routes(struct kernel_route *routes, int maxroutes)
{
    int rc, i;
    int count;
    struct kernel_route * proute = routes;
    struct kernel_route * pdest = proute;
    
    memset(routes, 0, sizeof(struct kernel_route) * maxroutes);

    rc = cyginet_dump_route_table(routes, maxroutes);
    if (rc < 0)
        return -1;

    count = 0;
    for (i = 0; i < rc; i++, proute++) {

        if (parse_kernel_route(proute) != 0)
            continue;
        
        if (proute != pdest)
            memcpy(pdest, proute, sizeof(struct kernel_route));

        if(debug > 2)
            print_kernel_route(RTM_ADD, pdest);

        pdest++;
    }
    return (pdest - routes);
}

int
kernel_addresses(char *ifname, int ifindex, int ll,
                 struct kernel_route *routes, int maxroutes)
{
    struct ifaddrs *ifa, *ifap;
    int rc, i;
    /* Two issues:
     * 1. ifname maybe includes a suffix number in the cygwin
     * 2. Ipv4 IfIndex maybe need to be changed as Ipv6IfIndex
     */
    rc = getifaddrs(&ifa);
    if(rc < 0)
        return -1;

    ifap = ifa;
    i = 0;

    while(ifap && i < maxroutes) {
        if((ifname != NULL && strcmp(ifap->ifa_name, ifname) != 0))
            goto next;
        if(ifap->ifa_addr->sa_family == AF_INET6) {
            struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)ifap->ifa_addr;
            if(!!ll != !!IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr))
                goto next;
            memcpy(routes[i].prefix, &sin6->sin6_addr, 16);
            if(ll)
                /* This a perfect example of counter-productive optimisation :
                   KAME encodes interface index onto bytes 2 and 3, so we have to
                   reset those bytes to 0 before passing them to babeld. */
                memset(routes[i].prefix + 2, 0, 2);
            routes[i].plen = 128;
            routes[i].metric = 0;
            routes[i].ifindex = ifindex;
            routes[i].proto = RTPROT_BABEL_LOCAL;
            memset(routes[i].gw, 0, 16);
            i++;
        } else if(ifap->ifa_addr->sa_family == AF_INET) {
            struct sockaddr_in *sin = (struct sockaddr_in*)ifap->ifa_addr;
            if(ll)
                goto next;
#if defined(IN_LINKLOCAL)
            if(IN_LINKLOCAL(htonl(sin->sin_addr.s_addr)))
                goto next;
#endif
            memcpy(routes[i].prefix, v4prefix, 12);
            memcpy(routes[i].prefix + 12, &sin->sin_addr, 4);
            routes[i].plen = 128;
            routes[i].metric = 0;
            routes[i].ifindex = ifindex;
            routes[i].proto = RTPROT_BABEL_LOCAL;
            memset(routes[i].gw, 0, 16);
            i++;
        }
 next:
        ifap = ifap->ifa_next;
    }

    freeifaddrs(ifa);
    return i;
}

int
kernel_callback(int (*fn)(int, void*), void *closure)
{
    if (kernel_socket < 0) kernel_setup_socket(1);

    /* In the Windows, we can't get the exact changed route, but the
       route table is really changed. */
    kdebugf("Kernel table changed.");
    return fn(~0, closure);
}

/* Local Variables:      */
/* c-basic-offset: 4     */
/* indent-tabs-mode: nil */
/* End:                  */