tap.c

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/*
 * Copyright (C) 2010 Piotr Jaroszyński <p.jaroszynski@gmail.com>
 *
 * This program is free software; you can redistribute it 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 any later version.
 *
 * This program 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <ipxe/linux_api.h>
#include <ipxe/list.h>
#include <ipxe/linux.h>
#include <ipxe/malloc.h>
#include <ipxe/device.h>
#include <ipxe/netdevice.h>
#include <ipxe/iobuf.h>
#include <ipxe/ethernet.h>
#include <ipxe/settings.h>
#include <ipxe/socket.h>
 
/* This hack prevents pre-2.6.32 headers from redefining struct sockaddr */
#define _SYS_SOCKET_H
#define __GLIBC__ 2
#include <linux/socket.h>
#undef __GLIBC__
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/if_tun.h>
 
#define RX_BUF_SIZE 1536
#define RX_QUOTA 4
 
/** @file
 *
 * The TAP driver.
 *
 * The TAP is a Virtual Ethernet network device.
 */
 
struct tap_nic {
        /** Tap interface name */
        char * interface;
        /** File descriptor of the opened tap device */
        int fd;
};
 
/** Default MAC address */
static const uint8_t tap_default_mac[ETH_ALEN] =
        { 0x52, 0x54, 0x00, 0x12, 0x34, 0x56 };
 
/** Open the TAP device */
static int tap_open(struct net_device * netdev)
{
        struct tap_nic * nic = netdev->priv;
        struct ifreq ifr;
        int ret;
 
        nic->fd = linux_open("/dev/net/tun", O_RDWR);
        if (nic->fd < 0) {
                DBGC(nic, "tap %p open('/dev/net/tun') = %d (%s)\n", nic, nic->fd, linux_strerror(linux_errno));
                return nic->fd;
        }
 
        memset(&ifr, 0, sizeof(ifr));
        /* IFF_NO_PI for no extra packet information */
        ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
        strncpy(ifr.ifr_name, nic->interface, IFNAMSIZ);
        DBGC(nic, "tap %p interface = '%s'\n", nic, nic->interface);
 
        ret = linux_ioctl(nic->fd, TUNSETIFF, &ifr);
 
        if (ret != 0) {
                DBGC(nic, "tap %p ioctl(%d, ...) = %d (%s)\n", nic, nic->fd, ret, linux_strerror(linux_errno));
                linux_close(nic->fd);
                return ret;
        }
 
        /* Set nonblocking mode to make tap_poll easier */
        ret = linux_fcntl(nic->fd, F_SETFL, O_NONBLOCK);
 
        if (ret != 0) {
                DBGC(nic, "tap %p fcntl(%d, ...) = %d (%s)\n", nic, nic->fd, ret, linux_strerror(linux_errno));
                linux_close(nic->fd);
                return ret;
        }
 
        return 0;
}
 
/** Close the TAP device */
static void tap_close(struct net_device *netdev)
{
        struct tap_nic * nic = netdev->priv;
        linux_close(nic->fd);
}
 
/**
 * Transmit an ethernet packet.
 *
 * The packet can be written to the TAP device and marked as complete immediately.
 */
static int tap_transmit(struct net_device *netdev, struct io_buffer *iobuf)
{
        struct tap_nic * nic = netdev->priv;
        int rc;
 
        /* Pad and align packet */
        iob_pad(iobuf, ETH_ZLEN);
 
        rc = linux_write(nic->fd, iobuf->data, iobuf->tail - iobuf->data);
        DBGC2(nic, "tap %p wrote %d bytes\n", nic, rc);
        netdev_tx_complete(netdev, iobuf);
 
        return 0;
}
 
/** Poll for new packets */
static void tap_poll(struct net_device *netdev)
{
        struct tap_nic * nic = netdev->priv;
        struct pollfd pfd;
        struct io_buffer * iobuf;
        unsigned int quota = RX_QUOTA;
        int r;
 
        pfd.fd = nic->fd;
        pfd.events = POLLIN;
        if (linux_poll(&pfd, 1, 0) == -1) {
                DBGC(nic, "tap %p poll failed (%s)\n", nic, linux_strerror(linux_errno));
                return;
        }
        if ((pfd.revents & POLLIN) == 0)
                return;
 
        /* At this point we know there is at least one new packet to be read */
 
        iobuf = alloc_iob(RX_BUF_SIZE);
        if (! iobuf)
                goto allocfail;
 
        while (quota-- &&
               ((r = linux_read(nic->fd, iobuf->data, RX_BUF_SIZE)) > 0)) {
                DBGC2(nic, "tap %p read %d bytes\n", nic, r);
 
                iob_put(iobuf, r);
                netdev_rx(netdev, iobuf);
 
                iobuf = alloc_iob(RX_BUF_SIZE);
                if (! iobuf)
                        goto allocfail;
        }
 
        free_iob(iobuf);
        return;
 
allocfail:
        DBGC(nic, "tap %p alloc_iob failed\n", nic);
}
 
/**
 * Set irq.
 *
 * Not used on linux, provide a dummy implementation.
 */
static void tap_irq(struct net_device *netdev, int enable)
{
        struct tap_nic *nic = netdev->priv;
 
        DBGC(nic, "tap %p irq enable = %d\n", nic, enable);
}
 
/** Tap operations */
static struct net_device_operations tap_operations = {
        .open           = tap_open,
        .close          = tap_close,
        .transmit       = tap_transmit,
        .poll           = tap_poll,
        .irq            = tap_irq,
};
 
/** Handle a device request for the tap driver */
static int tap_probe(struct linux_device *device, struct linux_device_request *request)
{
        struct linux_setting *if_setting;
        struct net_device *netdev;
        struct tap_nic *nic;
        int rc;
 
        netdev = alloc_etherdev(sizeof(*nic));
        if (! netdev)
                return -ENOMEM;
 
        netdev_init(netdev, &tap_operations);
        nic = netdev->priv;
        linux_set_drvdata(device, netdev);
        netdev->dev = &device->dev;
        memcpy ( netdev->hw_addr, tap_default_mac, ETH_ALEN );
        memset(nic, 0, sizeof(*nic));
 
        /* Look for the mandatory if setting */
        if_setting = linux_find_setting("if", &request->settings);
 
        /* No if setting */
        if (! if_setting) {
                printf("tap missing a mandatory if setting\n");
                rc = -EINVAL;
                goto err_settings;
        }
 
        nic->interface = if_setting->value;
        snprintf ( device->dev.name, sizeof ( device->dev.name ), "%s",
                   nic->interface );
        device->dev.desc.bus_type = BUS_TYPE_TAP;
        if_setting->applied = 1;
 
        /* Apply rest of the settings */
        linux_apply_settings(&request->settings, &netdev->settings.settings);
 
        /* Register network device */
        if ((rc = register_netdev(netdev)) != 0)
                goto err_register;
 
        netdev_link_up(netdev);
 
        return 0;
 
        unregister_netdev(netdev);
err_register:
err_settings:
        netdev_nullify(netdev);
        netdev_put(netdev);
        return rc;
}
 
/** Remove the device */
static void tap_remove(struct linux_device *device)
{
        struct net_device *netdev = linux_get_drvdata(device);
        unregister_netdev(netdev);
        netdev_nullify(netdev);
        netdev_put(netdev);
}
 
/** Tap linux_driver */
struct linux_driver tap_driver __linux_driver = {
        .name = "tap",
        .probe = tap_probe,
        .remove = tap_remove,
};
 
/* Generate build rules */
LINUX_ROM ( "tap", "Linux TUN/TAP NIC" );