/*
 * Copyright (c) 2005 Reyk Floeter <reyk@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "includes.h"

#include <sys/types.h>
#include <sys/ioctl.h>

#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/ip.h>

#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "openbsd-compat/sys-queue.h"
#include "log.h"
#include "misc.h"
#include "sshbuf.h"
#include "channels.h"
#include "ssherr.h"

/*
 * This file contains various portability code for network support,
 * including tun/tap forwarding and routing domains.
 */

#if defined(SYS_RDOMAIN_LINUX) || defined(SSH_TUN_LINUX)
#include <linux/if.h>
#endif

#if defined(SYS_RDOMAIN_LINUX)
char *
sys_get_rdomain(int fd)
{
        char dev[IFNAMSIZ + 1];
        socklen_t len = sizeof(dev) - 1;

        if (getsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, dev, &len) == -1) {
                error("%s: cannot determine VRF for fd=%d : %s",
                    __func__, fd, strerror(errno));
                return NULL;
        }
        dev[len] = '\0';
        return strdup(dev);
}

int
sys_set_rdomain(int fd, const char *name)
{
        if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE,
            name, strlen(name)) == -1) {
                error("%s: setsockopt(%d, SO_BINDTODEVICE, %s): %s",
                    __func__, fd, name, strerror(errno));
                return -1;
        }
        return 0;
}

int
sys_valid_rdomain(const char *name)
{
        int fd;

        /*
         * This is a pretty crappy way to test. It would be better to
         * check whether "name" represents a VRF device, but apparently
         * that requires an rtnetlink transaction.
         */
        if ((fd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
                return 0;
        if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE,
            name, strlen(name)) == -1) {
                close(fd);
                return 0;
        }
        close(fd);
        return 1;
}
#elif defined(SYS_RDOMAIN_XXX)
/* XXX examples */
char *
sys_get_rdomain(int fd)
{
        return NULL;
}

int
sys_set_rdomain(int fd, const char *name)
{
        return -1;
}

int
valid_rdomain(const char *name)
{
        return 0;
}

void
sys_set_process_rdomain(const char *name)
{
        fatal("%s: not supported", __func__);
}
#endif /* defined(SYS_RDOMAIN_XXX) */

/*
 * This is the portable version of the SSH tunnel forwarding, it
 * uses some preprocessor definitions for various platform-specific
 * settings.
 *
 * SSH_TUN_LINUX        Use the (newer) Linux tun/tap device
 * SSH_TUN_FREEBSD      Use the FreeBSD tun/tap device
 * SSH_TUN_COMPAT_AF    Translate the OpenBSD address family
 * SSH_TUN_PREPEND_AF   Prepend/remove the address family
 */

/*
 * System-specific tunnel open function
 */

#if defined(SSH_TUN_LINUX)
#include <linux/if_tun.h>
#define TUN_CTRL_DEV "/dev/net/tun"

int
sys_tun_open(int tun, int mode, char **ifname)
{
        struct ifreq ifr;
        int fd = -1;
        const char *name = NULL;

        if (ifname != NULL)
                *ifname = NULL;
        if ((fd = open(TUN_CTRL_DEV, O_RDWR)) == -1) {
                debug("%s: failed to open tunnel control device \"%s\": %s",
                    __func__, TUN_CTRL_DEV, strerror(errno));
                return (-1);
        }

        bzero(&ifr, sizeof(ifr));

        if (mode == SSH_TUNMODE_ETHERNET) {
                ifr.ifr_flags = IFF_TAP;
                name = "tap%d";
        } else {
                ifr.ifr_flags = IFF_TUN;
                name = "tun%d";
        }
        ifr.ifr_flags |= IFF_NO_PI;

        if (tun != SSH_TUNID_ANY) {
                if (tun > SSH_TUNID_MAX) {
                        debug("%s: invalid tunnel id %x: %s", __func__,
                            tun, strerror(errno));
                        goto failed;
                }
                snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), name, tun);
        }

        if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
                debug("%s: failed to configure tunnel (mode %d): %s", __func__,
                    mode, strerror(errno));
                goto failed;
        }

        if (tun == SSH_TUNID_ANY)
                debug("%s: tunnel mode %d fd %d", __func__, mode, fd);
        else
                debug("%s: %s mode %d fd %d", __func__, ifr.ifr_name, mode, fd);

        if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)) == NULL)
                goto failed;

        return (fd);

 failed:
        close(fd);
        return (-1);
}
#endif /* SSH_TUN_LINUX */

#ifdef SSH_TUN_FREEBSD
#include <sys/socket.h>
#include <net/if.h>

#ifdef HAVE_NET_IF_TUN_H
#include <net/if_tun.h>
#endif

int
sys_tun_open(int tun, int mode, char **ifname)
{
        struct ifreq ifr;
        char name[100];
        int fd = -1, sock;
        const char *tunbase = "tun";
#if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF)
        int flag;
#endif

        if (ifname != NULL)
                *ifname = NULL;

        if (mode == SSH_TUNMODE_ETHERNET) {
#ifdef SSH_TUN_NO_L2
                debug("%s: no layer 2 tunnelling support", __func__);
                return (-1);
#else
                tunbase = "tap";
#endif
        }

        /* Open the tunnel device */
        if (tun <= SSH_TUNID_MAX) {
                snprintf(name, sizeof(name), "/dev/%s%d", tunbase, tun);
                fd = open(name, O_RDWR);
        } else if (tun == SSH_TUNID_ANY) {
                for (tun = 100; tun >= 0; tun--) {
                        snprintf(name, sizeof(name), "/dev/%s%d",
                            tunbase, tun);
                        if ((fd = open(name, O_RDWR)) >= 0)
                                break;
                }
        } else {
                debug("%s: invalid tunnel %u\n", __func__, tun);
                return (-1);
        }

        if (fd < 0) {
                debug("%s: %s open failed: %s", __func__, name,
                    strerror(errno));
                return (-1);
        }

        /* Turn on tunnel headers */
#if defined(TUNSIFHEAD) && !defined(SSH_TUN_PREPEND_AF)
        flag = 1;
        if (mode != SSH_TUNMODE_ETHERNET &&
            ioctl(fd, TUNSIFHEAD, &flag) == -1) {
                debug("%s: ioctl(%d, TUNSIFHEAD, 1): %s", __func__, fd,
                    strerror(errno));
                close(fd);
        }
#endif

        debug("%s: %s mode %d fd %d", __func__, name, mode, fd);

        /* Set the tunnel device operation mode */
        snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s%d", tunbase, tun);
        if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) == -1)
                goto failed;

        if (ioctl(sock, SIOCGIFFLAGS, &ifr) == -1)
                goto failed;
        if ((ifr.ifr_flags & IFF_UP) == 0) {
                ifr.ifr_flags |= IFF_UP;
                if (ioctl(sock, SIOCSIFFLAGS, &ifr) == -1)
                        goto failed;
        }

        if (ifname != NULL && (*ifname = strdup(ifr.ifr_name)) == NULL)
                goto failed;

        close(sock);
        return (fd);

 failed:
        if (fd >= 0)
                close(fd);
        if (sock >= 0)
                close(sock);
        debug("%s: failed to set %s mode %d: %s", __func__, name,
            mode, strerror(errno));
        return (-1);
}
#endif /* SSH_TUN_FREEBSD */

/*
 * System-specific channel filters
 */

#if defined(SSH_TUN_FILTER)
/*
 * The tunnel forwarding protocol prepends the address family of forwarded
 * IP packets using OpenBSD's numbers.
 */
#define OPENBSD_AF_INET         2
#define OPENBSD_AF_INET6        24

int
sys_tun_infilter(struct ssh *ssh, struct Channel *c, char *buf, int _len)
{
        int r;
        size_t len;
        char *ptr = buf;
#if defined(SSH_TUN_PREPEND_AF)
        char rbuf[CHAN_RBUF];
        struct ip iph;
#endif
#if defined(SSH_TUN_PREPEND_AF) || defined(SSH_TUN_COMPAT_AF)
        u_int32_t af;
#endif

        /* XXX update channel input filter API to use unsigned length */
        if (_len < 0)
                return -1;
        len = _len;

#if defined(SSH_TUN_PREPEND_AF)
        if (len <= sizeof(iph) || len > sizeof(rbuf) - 4)
                return -1;
        /* Determine address family from packet IP header. */
        memcpy(&iph, buf, sizeof(iph));
        af = iph.ip_v == 6 ? OPENBSD_AF_INET6 : OPENBSD_AF_INET;
        /* Prepend address family to packet using OpenBSD constants */
        memcpy(rbuf + 4, buf, len);
        len += 4;
        POKE_U32(rbuf, af);
        ptr = rbuf;
#elif defined(SSH_TUN_COMPAT_AF)
        /* Convert existing address family header to OpenBSD value */
        if (len <= 4)
                return -1;
        af = PEEK_U32(buf);
        /* Put it back */
        POKE_U32(buf, af == AF_INET6 ? OPENBSD_AF_INET6 : OPENBSD_AF_INET);
#endif

        if ((r = sshbuf_put_string(c->input, ptr, len)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));
        return (0);
}

u_char *
sys_tun_outfilter(struct ssh *ssh, struct Channel *c,
    u_char **data, size_t *dlen)
{
        u_char *buf;
        u_int32_t af;
        int r;

        /* XXX new API is incompatible with this signature. */
        if ((r = sshbuf_get_string(c->output, data, dlen)) != 0)
                fatal("%s: buffer error: %s", __func__, ssh_err(r));
        if (*dlen < sizeof(af))
                return (NULL);
        buf = *data;

#if defined(SSH_TUN_PREPEND_AF)
        /* skip address family */
        *dlen -= sizeof(af);
        buf = *data + sizeof(af);
#elif defined(SSH_TUN_COMPAT_AF)
        /* translate address family */
        af = (PEEK_U32(buf) == OPENBSD_AF_INET6) ? AF_INET6 : AF_INET;
        POKE_U32(buf, af);
#endif
        return (buf);
}
#endif /* SSH_TUN_FILTER */