256 lines
6.2 KiB
C++
256 lines
6.2 KiB
C++
/*
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* \brief NIC driver for Linux TUN/TAP device
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* \author Stefan Kalkowski
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* \author Christian Helmuth
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* \author Sebastian Sumpf
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* \date 2011-08-08
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*
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* Configuration options are:
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*
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* - TAP device to connect to (default is tap0)
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* - MAC address (default is 02-00-00-00-00-01)
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*
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* These can be set in the config section as follows:
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* <config>
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* <nic mac="12:23:34:45:56:67" tap="tap1"/>
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* </config>
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*/
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/*
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* Copyright (C) 2011-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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/* Genode */
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/*
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* Needs to be included first because otherwise
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* util/xml_node.h will not pick up the ascii_to
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* overload.
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*/
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#include <nic/xml_node.h>
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#include <base/attached_rom_dataspace.h>
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#include <base/component.h>
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#include <base/heap.h>
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#include <base/thread.h>
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#include <base/log.h>
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#include <nic/root.h>
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/* Linux */
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#include <errno.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <net/if.h>
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#include <linux/if_tun.h>
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namespace Server {
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using namespace Genode;
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struct Main;
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}
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class Linux_session_component : public Nic::Session_component
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{
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private:
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struct Rx_signal_thread : Genode::Thread
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{
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int fd;
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Genode::Signal_context_capability sigh;
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Rx_signal_thread(Genode::Env &env, int fd, Genode::Signal_context_capability sigh)
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: Genode::Thread(env, "rx_signal", 0x1000), fd(fd), sigh(sigh) { }
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void entry() override
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{
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while (true) {
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/* wait for packet arrival on fd */
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int ret;
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fd_set rfds;
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FD_ZERO(&rfds);
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FD_SET(fd, &rfds);
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do { ret = select(fd + 1, &rfds, 0, 0, 0); } while (ret < 0);
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/* signal incoming packet */
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Genode::Signal_transmitter(sigh).submit();
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}
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}
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};
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Genode::Attached_rom_dataspace _config_rom;
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Nic::Mac_address _mac_addr { };
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int _tap_fd;
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Rx_signal_thread _rx_thread;
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int _setup_tap_fd()
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{
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/* open TAP device */
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int ret;
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struct ifreq ifr;
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int fd = open("/dev/net/tun", O_RDWR);
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if (fd < 0) {
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Genode::error("could not open /dev/net/tun: no virtual network emulation");
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/* this error is fatal */
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throw Genode::Exception();
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}
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/* set fd to non-blocking */
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if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) {
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Genode::error("could not set /dev/net/tun to non-blocking");
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throw Genode::Exception();
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}
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Genode::memset(&ifr, 0, sizeof(ifr));
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ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
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/* get tap device from config */
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try {
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Genode::Xml_node nic_node = _config_rom.xml().sub_node("nic");
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nic_node.attribute("tap").with_raw_value([&] (char const *ptr, size_t len) {
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len = Genode::min(len, sizeof(ifr.ifr_name) - 1);
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Genode::memcpy(ifr.ifr_name, ptr, len);
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ifr.ifr_name[len] = 0;
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});
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Genode::log("using tap device \"", Genode::Cstring(ifr.ifr_name), "\"");
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} catch (...) {
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/* use tap0 if no config has been provided */
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Genode::copy_cstring(ifr.ifr_name, "tap0", sizeof(ifr.ifr_name));
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Genode::log("no config provided, using tap0");
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}
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ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
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if (ret != 0) {
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Genode::error("could not configure /dev/net/tun: no virtual network emulation");
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close(fd);
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/* this error is fatal */
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throw Genode::Exception();
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}
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return fd;
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}
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bool _send()
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{
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using namespace Genode;
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if (!_tx.sink()->ready_to_ack())
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return false;
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if (!_tx.sink()->packet_avail())
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return false;
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Packet_descriptor packet = _tx.sink()->get_packet();
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if (!packet.size() || !_tx.sink()->packet_valid(packet)) {
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warning("invalid tx packet");
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return true;
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}
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int ret;
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/* non-blocking-write packet to TAP */
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do {
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ret = write(_tap_fd, _tx.sink()->packet_content(packet), packet.size());
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/* drop packet if write would block */
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if (ret < 0 && errno == EAGAIN)
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continue;
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if (ret < 0) Genode::error("write: errno=", errno);
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} while (ret < 0);
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_tx.sink()->acknowledge_packet(packet);
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return true;
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}
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bool _receive()
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{
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unsigned const max_size = Nic::Packet_allocator::DEFAULT_PACKET_SIZE;
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if (!_rx.source()->ready_to_submit())
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return false;
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Nic::Packet_descriptor p;
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try {
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p = _rx.source()->alloc_packet(max_size);
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} catch (Session::Rx::Source::Packet_alloc_failed) { return false; }
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int size = read(_tap_fd, _rx.source()->packet_content(p), max_size);
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if (size <= 0) {
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_rx.source()->release_packet(p);
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return false;
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}
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/* adjust packet size */
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Nic::Packet_descriptor p_adjust(p.offset(), size);
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_rx.source()->submit_packet(p_adjust);
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return true;
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}
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protected:
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void _handle_packet_stream() override
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{
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while (_rx.source()->ack_avail())
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_rx.source()->release_packet(_rx.source()->get_acked_packet());
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while (_send()) ;
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while (_receive()) ;
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}
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public:
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Linux_session_component(Genode::size_t const tx_buf_size,
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Genode::size_t const rx_buf_size,
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Genode::Allocator &rx_block_md_alloc,
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Server::Env &env)
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:
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Session_component(tx_buf_size, rx_buf_size, Genode::CACHED, rx_block_md_alloc, env),
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_config_rom(env, "config"),
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_tap_fd(_setup_tap_fd()), _rx_thread(env, _tap_fd, _packet_stream_dispatcher)
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{
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/* fall back to fake MAC address (unicast, locally managed) */
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_mac_addr.addr[0] = 0x02;
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_mac_addr.addr[1] = 0x00;
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_mac_addr.addr[2] = 0x00;
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_mac_addr.addr[3] = 0x00;
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_mac_addr.addr[4] = 0x00;
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_mac_addr.addr[5] = 0x01;
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/* try using configured MAC address */
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try {
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Genode::Xml_node nic_config = _config_rom.xml().sub_node("nic");
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_mac_addr = nic_config.attribute_value("mac", _mac_addr);
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Genode::log("Using configured MAC address ", _mac_addr);
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} catch (...) { }
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_rx_thread.start();
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}
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bool link_state() override { return true; }
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Nic::Mac_address mac_address() override { return _mac_addr; }
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};
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struct Server::Main
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{
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Env &_env;
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Heap _heap { _env.ram(), _env.rm() };
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Nic::Root<Linux_session_component> nic_root { _env, _heap };
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Main(Env &env) : _env(env)
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{
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_env.parent().announce(_env.ep().manage(nic_root));
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}
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};
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void Component::construct(Genode::Env &env) { static Server::Main main(env); }
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