[linux] Add the tap driver

Add the tap driver that can be used like:
$ ./ipxe.linux --net tap,if=tap0,mac=00:0c:29:c5:39:a1
The if setting is mandatory.

Signed-off-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/config.c

@@ -263,3 +263,8 @@ REQUIRE_OBJECT ( gdbstub_cmd );
  */
 REQUIRE_OBJECT ( device );
 REQUIRE_OBJECT ( embedded );
+
+/* linux drivers aren't picked up by the parserom utility so drag them in here */
+#ifdef DRIVERS_LINUX
+REQUIRE_OBJECT ( tap );
+#endif

src/config/defaults/linux.h

@@ -14,6 +14,8 @@
 #define NAP_LINUX
 #define SMBIOS_LINUX
 
+#define DRIVERS_LINUX
+
 #define IMAGE_SCRIPT
 
 #endif /* CONFIG_DEFAULTS_LINUX_H */

src/drivers/linux/tap.c

@@ -0,0 +1,249 @@
+/*
+ * 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 <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 __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
+
+/** @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;
+};
+
+/** 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;
+	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 ((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;
+	memset(nic, 0, sizeof(*nic));
+
+	netdev_link_up(netdev);
+
+	if ((rc = register_netdev(netdev)) != 0)
+		goto err_register;
+
+	/* 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;
+	if_setting->applied = 1;
+
+	/* Apply rest of the settings */
+	linux_apply_settings(&request->settings, &netdev->settings.settings);
+
+	return 0;
+
+err_settings:
+	unregister_netdev(netdev);
+err_register:
+	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,
+	.can_probe = 1,
+};

src/include/ipxe/errfile.h

@@ -128,6 +128,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_snponly		     ( ERRFILE_DRIVER | 0x005a0000 )
 #define ERRFILE_jme		     ( ERRFILE_DRIVER | 0x005b0000 )
 #define ERRFILE_virtio_net	     ( ERRFILE_DRIVER | 0x005c0000 )
+#define ERRFILE_tap		     ( ERRFILE_DRIVER | 0x005d0000 )
 
 #define ERRFILE_scsi		     ( ERRFILE_DRIVER | 0x00700000 )
 #define ERRFILE_arbel		     ( ERRFILE_DRIVER | 0x00710000 )