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 "net/tap.h"

#include "net/tap-linux.h"

#include <net/if.h>

#include <sys/ioctl.h>

#include "sysemu.h"

#include "qemu-common.h"

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

{

    struct ifreq ifr;

    int fd, ret;

    TFR(fd = open("/dev/net/tun", O_RDWR));

    if (fd < 0) {

        fprintf(stderr, "warning: could not open /dev/net/tun: no virtual network emulation\n");

        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;

        }

        if (vnet_hdr_required && !*vnet_hdr) {

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

                       "support for IFF_VNET_HDR available");

            close(fd);

            return -1;

        }

    }

    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) {

        fprintf(stderr, "warning: could not configure /dev/net/tun: no virtual network emulation\n");

        close(fd);

        return -1;

    }

    pstrcpy(ifname, ifname_size, ifr.ifr_name);

    fcntl(fd, F_SETFL, O_NONBLOCK);

    return fd;

}

/* 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 default, given a 1500 byte MTU.

 */

#define TAP_DEFAULT_SNDBUF 1024*1024

int tap_set_sndbuf(int fd, QemuOpts *opts)

{

    int sndbuf;

    sndbuf = qemu_opt_get_size(opts, "sndbuf", TAP_DEFAULT_SNDBUF);

    if (!sndbuf) {

        sndbuf = INT_MAX;

    }

    if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && qemu_opt_get(opts, "sndbuf")) {

        qemu_error("TUNSETSNDBUF ioctl failed: %s\n", strerror(errno));

        return -1;

    }

    return 0;

}