Archipelago » qemu

/*

 * QEMU System Emulator

 *

 * Copyright (c) 2003-2008 Fabrice Bellard

 * Copyright (c) 2009 Red Hat, Inc.

 *

 * 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 "tap_int.h"

#include "tap-linux.h"

#include "net/tap.h"

#include <net/if.h>

#include <sys/ioctl.h>

#include "sysemu/sysemu.h"

#include "qemu-common.h"

#include "qemu/error-report.h"

#define PATH_NET_TUN "/dev/net/tun"

int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required)

{

    struct ifreq ifr;

    int fd, ret;

    int len = sizeof(struct virtio_net_hdr);

    TFR(fd = open(PATH_NET_TUN, O_RDWR));

    if (fd < 0) {

        error_report("could not open %s: %m", PATH_NET_TUN);

        return -1;

    }

    memset(&ifr, 0, sizeof(ifr));

    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;

    if (*vnet_hdr) {

        unsigned int features;

        if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&

            features & IFF_VNET_HDR) {

            *vnet_hdr = 1;

            ifr.ifr_flags |= IFF_VNET_HDR;

        } else {

            *vnet_hdr = 0;

        }

        if (vnet_hdr_required && !*vnet_hdr) {

            error_report("vnet_hdr=1 requested, but no kernel "

                         "support for IFF_VNET_HDR available");

            close(fd);

            return -1;

        }

        /*

         * Make sure vnet header size has the default value: for a persistent

         * tap it might have been modified e.g. by another instance of qemu.

         * Ignore errors since old kernels do not support this ioctl: in this

         * case the header size implicitly has the correct value.

         */

        ioctl(fd, TUNSETVNETHDRSZ, &len);

    }

    if (ifname[0] != '\0')

        pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);

    else

        pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");

    ret = ioctl(fd, TUNSETIFF, (void *) &ifr);

    if (ret != 0) {

        if (ifname[0] != '\0') {

            error_report("could not configure %s (%s): %m", PATH_NET_TUN, ifr.ifr_name);

        } else {

            error_report("could not configure %s: %m", PATH_NET_TUN);

        }

        close(fd);

        return -1;

    }

    pstrcpy(ifname, ifname_size, ifr.ifr_name);

    fcntl(fd, F_SETFL, O_NONBLOCK);

    return fd;

}

/* sndbuf implements a kind of flow control for tap.

 * Unfortunately when it's enabled, and packets are sent

 * to other guests on the same host, the receiver

 * can lock up the transmitter indefinitely.

 *

 * To avoid packet loss, sndbuf should be set to a value lower than the tx

 * queue capacity of any destination network interface.

 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is

 * a good value, given a 1500 byte MTU.

 */

#define TAP_DEFAULT_SNDBUF 0

int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)

{

    int sndbuf;

    sndbuf = !tap->has_sndbuf       ? TAP_DEFAULT_SNDBUF :

             tap->sndbuf > INT_MAX  ? INT_MAX :

             tap->sndbuf;

    if (!sndbuf) {

        sndbuf = INT_MAX;

    }

    if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {

        error_report("TUNSETSNDBUF ioctl failed: %s", strerror(errno));

        return -1;

    }

    return 0;

}

int tap_probe_vnet_hdr(int fd)

{

    struct ifreq ifr;

    if (ioctl(fd, TUNGETIFF, &ifr) != 0) {

        error_report("TUNGETIFF ioctl() failed: %s", strerror(errno));

        return 0;

    }

    return ifr.ifr_flags & IFF_VNET_HDR;

}

int tap_probe_has_ufo(int fd)

{

    unsigned offload;

    offload = TUN_F_CSUM | TUN_F_UFO;

    if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)

        return 0;

    return 1;

}

/* Verify that we can assign given length */

int tap_probe_vnet_hdr_len(int fd, int len)

{

    int orig;

    if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {

        return 0;

    }

    if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {

        return 0;

    }

    /* Restore original length: we can't handle failure. */

    if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {

        fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",

                strerror(errno));

        assert(0);

        return -errno;

    }

    return 1;

}

void tap_fd_set_vnet_hdr_len(int fd, int len)

{

    if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {

        fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",

                strerror(errno));

        assert(0);

    }

}

void tap_fd_set_offload(int fd, int csum, int tso4,

                        int tso6, int ecn, int ufo)

{

    unsigned int offload = 0;

    /* Check if our kernel supports TUNSETOFFLOAD */

    if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {

        return;

    }

    if (csum) {

        offload |= TUN_F_CSUM;

        if (tso4)

            offload |= TUN_F_TSO4;

        if (tso6)

            offload |= TUN_F_TSO6;

        if ((tso4 || tso6) && ecn)

            offload |= TUN_F_TSO_ECN;

        if (ufo)

            offload |= TUN_F_UFO;

    }

    if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {

        offload &= ~TUN_F_UFO;

        if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {

            fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",

                    strerror(errno));

        }

    }

}