ethertap.cc revision 12056:1ad5b3161819 
1/*
2 * Copyright (c) 2003-2005 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Nathan Binkert
29 */
30
31/* @file
32 * Interface to connect a simulated ethernet device to the real world
33 */
34
35#include "dev/net/ethertap.hh"
36
37#if defined(__OpenBSD__) || defined(__APPLE__)
38#include <sys/param.h>
39
40#endif
41
42#if USE_TUNTAP && defined(__linux__)
43#if 1 // Hide from the style checker since these have to be out of order.
44#include <sys/socket.h> // Has to be included before if.h for some reason.
45
46#endif
47
48#include <linux/if.h>
49#include <linux/if_tun.h>
50
51#endif
52
53#include <fcntl.h>
54#include <netinet/in.h>
55#include <sys/ioctl.h>
56#include <unistd.h>
57
58#include <cstring>
59#include <deque>
60#include <string>
61
62#include "base/misc.hh"
63#include "base/pollevent.hh"
64#include "base/socket.hh"
65#include "base/trace.hh"
66#include "debug/Ethernet.hh"
67#include "debug/EthernetData.hh"
68#include "dev/net/etherdump.hh"
69#include "dev/net/etherint.hh"
70#include "dev/net/etherpkt.hh"
71
72using namespace std;
73
74class TapEvent : public PollEvent
75{
76  protected:
77    EtherTapBase *tap;
78
79  public:
80    TapEvent(EtherTapBase *_tap, int fd, int e)
81        : PollEvent(fd, e), tap(_tap) {}
82    virtual void process(int revent) { tap->recvReal(revent); }
83};
84
85EtherTapBase::EtherTapBase(const Params *p)
86    : EtherObject(p), buflen(p->bufsz), dump(p->dump), event(NULL),
87      interface(NULL), txEvent(this)
88{
89    buffer = new uint8_t[buflen];
90    interface = new EtherTapInt(name() + ".interface", this);
91}
92
93EtherTapBase::~EtherTapBase()
94{
95    delete buffer;
96    delete event;
97    delete interface;
98}
99
100void
101EtherTapBase::serialize(CheckpointOut &cp) const
102{
103    SERIALIZE_SCALAR(buflen);
104    uint8_t *buffer = (uint8_t *)this->buffer;
105    SERIALIZE_ARRAY(buffer, buflen);
106
107    bool tapevent_present = false;
108    if (event) {
109        tapevent_present = true;
110        SERIALIZE_SCALAR(tapevent_present);
111        event->serialize(cp);
112    } else {
113        SERIALIZE_SCALAR(tapevent_present);
114    }
115}
116
117void
118EtherTapBase::unserialize(CheckpointIn &cp)
119{
120    UNSERIALIZE_SCALAR(buflen);
121    uint8_t *buffer = (uint8_t *)this->buffer;
122    UNSERIALIZE_ARRAY(buffer, buflen);
123
124    bool tapevent_present;
125    UNSERIALIZE_SCALAR(tapevent_present);
126    if (tapevent_present) {
127        event = new TapEvent(this, 0, 0);
128        event->unserialize(cp);
129        if (event->queued())
130            pollQueue.schedule(event);
131    }
132}
133
134
135void
136EtherTapBase::pollFd(int fd)
137{
138    assert(!event);
139    event = new TapEvent(this, fd, POLLIN|POLLERR);
140    pollQueue.schedule(event);
141}
142
143void
144EtherTapBase::stopPolling()
145{
146    assert(event);
147    delete event;
148    event = NULL;
149}
150
151
152EtherInt*
153EtherTapBase::getEthPort(const std::string &if_name, int idx)
154{
155    if (if_name == "tap") {
156        if (interface->getPeer())
157            panic("Interface already connected to\n");
158        return interface;
159    }
160    return NULL;
161}
162
163bool
164EtherTapBase::recvSimulated(EthPacketPtr packet)
165{
166    if (dump)
167        dump->dump(packet);
168
169    DPRINTF(Ethernet, "EtherTap sim->real len=%d\n", packet->length);
170    DDUMP(EthernetData, packet->data, packet->length);
171
172    bool success = sendReal(packet->data, packet->length);
173
174    interface->recvDone();
175
176    return success;
177}
178
179void
180EtherTapBase::sendSimulated(void *data, size_t len)
181{
182    EthPacketPtr packet;
183    packet = make_shared<EthPacketData>(len);
184    packet->length = len;
185    packet->simLength = len;
186    memcpy(packet->data, data, len);
187
188    DPRINTF(Ethernet, "EtherTap real->sim len=%d\n", packet->length);
189    DDUMP(EthernetData, packet->data, packet->length);
190    if (!packetBuffer.empty() || !interface->sendPacket(packet)) {
191        DPRINTF(Ethernet, "bus busy...buffer for retransmission\n");
192        packetBuffer.push(packet);
193        if (!txEvent.scheduled())
194            schedule(txEvent, curTick() + retryTime);
195    } else if (dump) {
196        dump->dump(packet);
197    }
198}
199
200void
201EtherTapBase::retransmit()
202{
203    if (packetBuffer.empty())
204        return;
205
206    EthPacketPtr packet = packetBuffer.front();
207    if (interface->sendPacket(packet)) {
208        if (dump)
209            dump->dump(packet);
210        DPRINTF(Ethernet, "EtherTap retransmit\n");
211        packetBuffer.front() = NULL;
212        packetBuffer.pop();
213    }
214
215    if (!packetBuffer.empty() && !txEvent.scheduled())
216        schedule(txEvent, curTick() + retryTime);
217}
218
219
220class TapListener
221{
222  protected:
223    class Event : public PollEvent
224    {
225      protected:
226        TapListener *listener;
227
228      public:
229        Event(TapListener *l, int fd, int e) : PollEvent(fd, e), listener(l) {}
230
231        void process(int revent) override { listener->accept(); }
232    };
233
234    friend class Event;
235    Event *event;
236
237    void accept();
238
239  protected:
240    ListenSocket listener;
241    EtherTapStub *tap;
242    int port;
243
244  public:
245    TapListener(EtherTapStub *t, int p) : event(NULL), tap(t), port(p) {}
246    ~TapListener() { delete event; }
247
248    void listen();
249};
250
251void
252TapListener::listen()
253{
254    while (!listener.listen(port, true)) {
255        DPRINTF(Ethernet, "TapListener(listen): Can't bind port %d\n", port);
256        port++;
257    }
258
259    ccprintf(cerr, "Listening for tap connection on port %d\n", port);
260    event = new Event(this, listener.getfd(), POLLIN|POLLERR);
261    pollQueue.schedule(event);
262}
263
264void
265TapListener::accept()
266{
267    // As a consequence of being called from the PollQueue, we might
268    // have been called from a different thread. Migrate to "our"
269    // thread.
270    EventQueue::ScopedMigration migrate(tap->eventQueue());
271
272    if (!listener.islistening())
273        panic("TapListener(accept): cannot accept if we're not listening!");
274
275    int sfd = listener.accept(true);
276    if (sfd != -1)
277        tap->attach(sfd);
278}
279
280
281EtherTapStub::EtherTapStub(const Params *p) : EtherTapBase(p), socket(-1)
282{
283    if (ListenSocket::allDisabled())
284        fatal("All listeners are disabled! EtherTapStub can't work!");
285
286    listener = new TapListener(this, p->port);
287    listener->listen();
288}
289
290EtherTapStub::~EtherTapStub()
291{
292    delete listener;
293}
294
295void
296EtherTapStub::serialize(CheckpointOut &cp) const
297{
298    EtherTapBase::serialize(cp);
299
300    SERIALIZE_SCALAR(socket);
301    SERIALIZE_SCALAR(buffer_used);
302    SERIALIZE_SCALAR(frame_len);
303}
304
305void
306EtherTapStub::unserialize(CheckpointIn &cp)
307{
308    EtherTapBase::unserialize(cp);
309
310    UNSERIALIZE_SCALAR(socket);
311    UNSERIALIZE_SCALAR(buffer_used);
312    UNSERIALIZE_SCALAR(frame_len);
313}
314
315
316void
317EtherTapStub::attach(int fd)
318{
319    if (socket != -1)
320        close(fd);
321
322    buffer_used = 0;
323    frame_len = 0;
324    socket = fd;
325    DPRINTF(Ethernet, "EtherTapStub attached\n");
326    pollFd(socket);
327}
328
329void
330EtherTapStub::detach()
331{
332    DPRINTF(Ethernet, "EtherTapStub detached\n");
333    stopPolling();
334    close(socket);
335    socket = -1;
336}
337
338void
339EtherTapStub::recvReal(int revent)
340{
341    if (revent & POLLERR) {
342        detach();
343        return;
344    }
345
346    if (!(revent & POLLIN))
347        return;
348
349    // Read in as much of the new data as we can.
350    int len = read(socket, buffer + buffer_used, buflen - buffer_used);
351    if (len == 0) {
352        detach();
353        return;
354    }
355    buffer_used += len;
356
357    // If there's not enough data for the frame length, wait for more.
358    if (buffer_used < sizeof(uint32_t))
359        return;
360
361    if (frame_len == 0)
362        frame_len = ntohl(*(uint32_t *)buffer);
363
364    DPRINTF(Ethernet, "Received data from peer: len=%d buffer_used=%d "
365            "frame_len=%d\n", len, buffer_used, frame_len);
366
367    uint8_t *frame_start = &buffer[sizeof(uint32_t)];
368    while (frame_len != 0 && buffer_used >= frame_len + sizeof(uint32_t)) {
369        sendSimulated(frame_start, frame_len);
370
371        // Bookkeeping.
372        buffer_used -= frame_len + sizeof(uint32_t);
373        if (buffer_used > 0) {
374            // If there's still any data left, move it into position.
375            memmove(buffer, frame_start + frame_len, buffer_used);
376        }
377        frame_len = 0;
378
379        if (buffer_used >= sizeof(uint32_t))
380            frame_len = ntohl(*(uint32_t *)buffer);
381    }
382}
383
384bool
385EtherTapStub::sendReal(const void *data, size_t len)
386{
387    uint32_t frame_len = htonl(len);
388    ssize_t ret = write(socket, &frame_len, sizeof(frame_len));
389    if (ret != sizeof(frame_len))
390        return false;
391    return write(socket, data, len) == len;
392}
393
394
395#if USE_TUNTAP
396
397EtherTap::EtherTap(const Params *p) : EtherTapBase(p)
398{
399    int fd = open(p->tun_clone_device.c_str(), O_RDWR);
400    if (fd < 0)
401        panic("Couldn't open %s.\n", p->tun_clone_device);
402
403    struct ifreq ifr;
404    memset(&ifr, 0, sizeof(ifr));
405    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
406    strncpy(ifr.ifr_name, p->tap_device_name.c_str(), IFNAMSIZ);
407
408    if (ioctl(fd, TUNSETIFF, (void *)&ifr) < 0)
409        panic("Failed to access tap device %s.\n", ifr.ifr_name);
410    // fd now refers to the tap device.
411    tap = fd;
412    pollFd(tap);
413}
414
415EtherTap::~EtherTap()
416{
417    stopPolling();
418    close(tap);
419    tap = -1;
420}
421
422void
423EtherTap::recvReal(int revent)
424{
425    if (revent & POLLERR)
426        panic("Error polling for tap data.\n");
427
428    if (!(revent & POLLIN))
429        return;
430
431    ssize_t ret = read(tap, buffer, buflen);
432    if (ret < 0)
433        panic("Failed to read from tap device.\n");
434
435    sendSimulated(buffer, ret);
436}
437
438bool
439EtherTap::sendReal(const void *data, size_t len)
440{
441    if (write(tap, data, len) != len)
442        panic("Failed to write data to tap device.\n");
443    return true;
444}
445
446EtherTap *
447EtherTapParams::create()
448{
449    return new EtherTap(this);
450}
451
452#endif
453
454EtherTapStub *
455EtherTapStubParams::create()
456{
457    return new EtherTapStub(this);
458}
459