zircon/system/dev/ethernet/ethertap/ethertap.cpp

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ethertap.h"

#include <ddk/debug.h>
#include <fbl/auto_lock.h>
#include <lib/fidl/cpp/message.h>
#include <lib/fidl/cpp/message_builder.h>
#include <pretty/hexdump.h>
#include <stdio.h>
#include <string.h>
#include <zircon/compiler.h>

#include <utility>

// This macro allows for per-device tracing rather than enabling tracing for the whole driver
#define ethertap_trace(args...)                      \
    do {                                             \
        if (unlikely(options_ & ETHERTAP_OPT_TRACE)) \
            zxlogf(INFO, "ethertap: " args);         \
    } while (0)

#define ETHERTAP_OPT_TRACE (fuchsia_hardware_ethertap_OPT_TRACE)
#define ETHERTAP_OPT_TRACE_PACKETS (fuchsia_hardware_ethertap_OPT_TRACE_PACKETS)
#define ETHERTAP_OPT_REPORT_PARAM (fuchsia_hardware_ethertap_OPT_REPORT_PARAM)
#define ETHERTAP_OPT_ONLINE (fuchsia_hardware_ethertap_OPT_ONLINE)

namespace eth {

static zx_status_t fidl_tap_ctl_open_device(void* ctx,
                                            const char* name_data,
                                            size_t name_size,
                                            const fuchsia_hardware_ethertap_Config* config,
                                            zx_handle_t device_handle,
                                            fidl_txn_t* txn) {
    auto ctl = static_cast<TapCtl*>(ctx);
    char name[fuchsia_hardware_ethertap_MAX_NAME_LENGTH + 1];
    strncpy(name, name_data, sizeof(name));
    name[fuchsia_hardware_ethertap_MAX_NAME_LENGTH] = '\0';
    auto status =
        ctl->OpenDevice(name, config, zx::channel(device_handle));
    return fuchsia_hardware_ethertap_TapControlOpenDevice_reply(txn, status);
}

static const fuchsia_hardware_ethertap_TapControl_ops_t tap_ctl_ops_ = {
    .OpenDevice = fidl_tap_ctl_open_device};

TapCtl::TapCtl(zx_device_t* device)
    : ddk::Device<TapCtl, ddk::Messageable>(device) {}

void TapCtl::DdkRelease() {
    delete this;
}

zx_status_t TapCtl::DdkMessage(fidl_msg_t* msg, fidl_txn_t* txn) {
    return fuchsia_hardware_ethertap_TapControl_dispatch(this, txn, msg, &tap_ctl_ops_);
}

zx_status_t TapCtl::OpenDevice(const char* name,
                               const fuchsia_hardware_ethertap_Config* config,
                               zx::channel device) {
    if (config->mtu > fuchsia_hardware_ethertap_MAX_MTU) {
        return ZX_ERR_INVALID_ARGS;
    }

    auto tap = fbl::unique_ptr<eth::TapDevice>(
        new eth::TapDevice(zxdev(), config, std::move(device)));

    auto status = tap->DdkAdd(name);

    if (status != ZX_OK) {
        zxlogf(ERROR, "tapctl: could not add tap device: %d\n", status);
    } else {
        // devmgr owns the memory until release is called
        __UNUSED auto ptr = tap.release();
        zxlogf(INFO, "tapctl: created ethertap device '%s'\n", name);
    }
    return status;
}

int tap_device_thread(void* arg) {
    TapDevice* device = reinterpret_cast<TapDevice*>(arg);
    return device->Thread();
}

#define TAP_SHUTDOWN ZX_USER_SIGNAL_7

static zx_status_t
fidl_tap_device_write_frame(void* ctx, const uint8_t* data_data, size_t data_count) {
    static_cast<TapDevice*>(ctx)->Recv(data_data, static_cast<uint32_t>(data_count));
    return ZX_OK;
}

static zx_status_t fidl_tap_device_set_online(void* ctx, bool online) {
    static_cast<TapDevice*>(ctx)->UpdateLinkStatus(online);
    return ZX_OK;
}

static const fuchsia_hardware_ethertap_TapDevice_ops_t tap_device_ops_ = {
    .WriteFrame = fidl_tap_device_write_frame,
    .SetOnline = fidl_tap_device_set_online};

TapDevice::TapDevice(zx_device_t* device,
                     const fuchsia_hardware_ethertap_Config* config,
                     zx::channel server)
    : ddk::Device<TapDevice, ddk::Unbindable>(device),
      options_(config->options),
      features_(config->features | ETHMAC_FEATURE_SYNTH),
      mtu_(config->mtu),
      online_((config->options & ETHERTAP_OPT_ONLINE) != 0),
      channel_(std::move(server)) {
    ZX_DEBUG_ASSERT(channel_.is_valid());
    memcpy(mac_, config->mac.octets, 6);

    int ret = thrd_create_with_name(&thread_, tap_device_thread, reinterpret_cast<void*>(this),
                                    "ethertap-thread");
    ZX_DEBUG_ASSERT(ret == thrd_success);
}

void TapDevice::DdkRelease() {
    ethertap_trace("DdkRelease\n");
    int ret = thrd_join(thread_, nullptr);
    ZX_DEBUG_ASSERT(ret == thrd_success);
    delete this;
}

void TapDevice::DdkUnbind() {
    ethertap_trace("DdkUnbind\n");
    fbl::AutoLock lock(&lock_);
    zx_status_t status = channel_.signal(0, TAP_SHUTDOWN);
    ZX_DEBUG_ASSERT(status == ZX_OK);
    // When the thread exits after the channel is closed, it will call DdkRemove.
}

zx_status_t TapDevice::EthmacQuery(uint32_t options, ethmac_info_t* info) {
    memset(info, 0, sizeof(*info));
    info->features = features_;
    info->mtu = mtu_;
    memcpy(info->mac, mac_, 6);
    info->netbuf_size = sizeof(ethmac_netbuf_t);
    return ZX_OK;
}

void TapDevice::EthmacStop() {
    ethertap_trace("EthmacStop\n");
    fbl::AutoLock lock(&lock_);
    ethmac_client_.clear();
}

zx_status_t TapDevice::EthmacStart(const ethmac_ifc_protocol_t* ifc) {
    ethertap_trace("EthmacStart\n");
    fbl::AutoLock lock(&lock_);
    if (ethmac_client_.is_valid()) {
        return ZX_ERR_ALREADY_BOUND;
    } else {
        ethmac_client_ = ddk::EthmacIfcProtocolClient(ifc);
        ethmac_client_.Status(online_ ? ETHMAC_STATUS_ONLINE : 0u);
    }
    return ZX_OK;
}

zx_status_t TapDevice::EthmacQueueTx(uint32_t options, ethmac_netbuf_t* netbuf) {
    fbl::AutoLock lock(&lock_);
    if (dead_) {
        return ZX_ERR_PEER_CLOSED;
    } else if (!online_) {
        ethertap_trace("dropping packet, device offline\n");
        return ZX_ERR_UNAVAILABLE;
    }

    size_t length = netbuf->data_size;
    ZX_DEBUG_ASSERT(length <= mtu_);

    FIDL_ALIGNDECL uint8_t temp_buff[sizeof(fuchsia_hardware_ethertap_TapDeviceOnFrameEvent) + FIDL_ALIGN(fuchsia_hardware_ethertap_MAX_MTU)];
    fidl::Builder builder(temp_buff, sizeof(temp_buff));
    auto* event = builder.New<fuchsia_hardware_ethertap_TapDeviceOnFrameEvent>();
    event->hdr.ordinal = fuchsia_hardware_ethertap_TapDeviceOnFrameOrdinal;
    event->hdr.flags = 0;
    event->hdr.txid = FIDL_TXID_NO_RESPONSE;
    event->data.count = length;
    auto* data = builder.NewArray<uint8_t>(static_cast<uint32_t>(length));
    event->data.data = data;
    memcpy(data, netbuf->data_buffer, length);

    const char* err = nullptr;
    fidl::Message msg(builder.Finalize(), fidl::HandlePart());
    auto status = msg.Encode(&fuchsia_hardware_ethertap_TapDeviceOnFrameEventTable, &err);
    if (status != ZX_OK) {
        zxlogf(ERROR, "ethertap: EthmacQueueTx error encoding: %d %s\n", status, err);
    } else {
        if (unlikely(options_ & ETHERTAP_OPT_TRACE_PACKETS)) {
            ethertap_trace("sending %zu bytes\n", length);
            hexdump8_ex(netbuf->data_buffer, length, 0);
        }

        status = msg.Write(channel_.get(), 0);

        if (status != ZX_OK) {
            zxlogf(ERROR, "ethertap: EthmacQueueTx error writing: %d\n", status);
        }
    }
    // returning ZX_ERR_SHOULD_WAIT indicates that we will call complete_tx(), which we will not
    return status == ZX_ERR_SHOULD_WAIT ? ZX_ERR_UNAVAILABLE : status;
}

zx_status_t TapDevice::EthmacSetParam(uint32_t param, int32_t value, const void* data,
                                      size_t data_size) {
    fbl::AutoLock lock(&lock_);
    if (!(options_ & ETHERTAP_OPT_REPORT_PARAM) || dead_) {
        return ZX_ERR_NOT_SUPPORTED;
    }

    FIDL_ALIGNDECL uint8_t temp_buff[sizeof(fuchsia_hardware_ethertap_TapDeviceOnReportParamsEvent) + FIDL_ALIGN(fuchsia_hardware_ethertap_MAX_PARAM_DATA)];
    fidl::Builder builder(temp_buff, sizeof(temp_buff));
    auto* event = builder.New<fuchsia_hardware_ethertap_TapDeviceOnReportParamsEvent>();
    event->hdr.ordinal = fuchsia_hardware_ethertap_TapDeviceOnReportParamsOrdinal;
    event->hdr.flags = 0;
    event->hdr.txid = FIDL_TXID_NO_RESPONSE;

    event->param = param;
    event->value = value;
    event->data.data = nullptr;
    event->data.count = 0;

    switch (param) {
    case ETHMAC_SETPARAM_MULTICAST_FILTER:
        if (value == ETHMAC_MULTICAST_FILTER_OVERFLOW) {
            break;
        } else {
            // Send the final byte of each address, sorted lowest-to-highest.
            auto size = static_cast<uint32_t>(value) < fuchsia_hardware_ethertap_MAX_PARAM_DATA
                            ? static_cast<uint32_t>(value)
                            : fuchsia_hardware_ethertap_MAX_PARAM_DATA;
            auto* report = builder.NewArray<uint8_t>(size);
            event->data.data = report;
            event->data.count = size;

            uint32_t i;
            for (i = 0; i < size; i++) {
                report[i] = static_cast<const uint8_t*>(data)[i * ETH_MAC_SIZE + 5];
            }
            qsort(report, size, 1,
                  [](const void* ap, const void* bp) {
                      int a = *static_cast<const uint8_t*>(ap);
                      int b = *static_cast<const uint8_t*>(bp);
                      return a < b ? -1 : (a > 1 ? 1 : 0);
                  });
        }
        break;
    default:
        break;
    }

    // A failure of sending the event data is not a simulated failure of hardware under test,
    // so log it but don't report failure on the SetParam attempt.

    const char* err = nullptr;
    fidl::Message msg(builder.Finalize(), fidl::HandlePart());
    auto status = msg.Encode(&fuchsia_hardware_ethertap_TapDeviceOnReportParamsEventTable, &err);
    if (status != ZX_OK) {
        zxlogf(ERROR, "ethertap: EthmacSetParam error encoding: %d %s\n", status, err);
    } else {
        status = msg.Write(channel_.get(), 0);

        if (status != ZX_OK) {
            zxlogf(ERROR, "ethertap: EthmacSetParam error writing: %d\n", status);
        }
    }

    return ZX_OK;
}

void TapDevice::EthmacGetBti(zx::bti* bti) {
    bti->reset();
}

void TapDevice::UpdateLinkStatus(bool online) {
    bool was_online = online_;

    if (online) {
        ethertap_trace("online asserted\n");
        online_ = true;
    } else {
        ethertap_trace("offline asserted\n");
        online_ = false;
    }

    if (was_online != online_) {
        fbl::AutoLock lock(&lock_);
        if (ethmac_client_.is_valid()) {
            ethmac_client_.Status(online_ ? ETHMAC_STATUS_ONLINE : 0u);
        }
        ethertap_trace("device '%s' is now %s\n", name(), online_ ? "online" : "offline");
    }
}

zx_status_t TapDevice::Recv(const uint8_t* buffer, uint32_t length) {
    fbl::AutoLock lock(&lock_);

    if (!online_) {
        ethertap_trace("attempted to push bytes to an offline device\n");
        return ZX_OK;
    }

    if (unlikely(options_ & ETHERTAP_OPT_TRACE_PACKETS)) {
        ethertap_trace("received %u bytes\n", length);
        hexdump8_ex(buffer, length, 0);
    }

    if (ethmac_client_.is_valid()) {
        ethmac_client_.Recv(buffer, length, 0u);
    }
    return ZX_OK;
}

typedef struct tap_device_txn {
    fidl_txn_t txn;
    zx_txid_t txid;
    TapDevice* device;
} tap_device_txn_t;

static zx_status_t tap_device_reply(fidl_txn_t* txn, const fidl_msg_t* msg) {
    static_assert(offsetof(tap_device_txn_t, txn) == 0,
                  "FidlConnection must be convertable to txn");
    auto* ptr = reinterpret_cast<tap_device_txn_t*>(txn);
    return ptr->device->Reply(ptr->txid, msg);
}

zx_status_t TapDevice::Reply(zx_txid_t txid, const fidl_msg_t* msg) {
    auto header = reinterpret_cast<fidl_message_header_t*>(msg->bytes);
    header->txid = txid;
    return channel_.write(0, msg->bytes, msg->num_bytes, msg->handles, msg->num_handles);
}

int TapDevice::Thread() {
    ethertap_trace("starting main thread\n");
    zx_signals_t pending;
    const uint32_t buff_size = 2 * mtu_;
    constexpr uint32_t handle_count = 8;
    fbl::unique_ptr<uint8_t[]> data_buff(new uint8_t[buff_size]);
    zx_handle_t handles_buff[handle_count];

    fidl_msg_t msg = {
        .bytes = data_buff.get(),
        .handles = handles_buff,
        .num_bytes = buff_size,
        .num_handles = handle_count,
    };

    tap_device_txn_t txn = {
        .txn = {.reply = tap_device_reply},
        .txid = 0,
        .device = this,
    };

    zx_status_t status = ZX_OK;
    const zx_signals_t wait = ZX_CHANNEL_READABLE | ZX_CHANNEL_PEER_CLOSED | TAP_SHUTDOWN;
    while (true) {
        status = channel_.wait_one(wait, zx::time::infinite(), &pending);
        if (status != ZX_OK) {
            ethertap_trace("error waiting on channel: %d\n", status);
            break;
        }

        if (pending & ZX_CHANNEL_READABLE) {
            status = channel_.read(0, msg.bytes, msg.handles, buff_size, handle_count,
                                   &msg.num_bytes, &msg.num_handles);
            if (status != ZX_OK) {
                ethertap_trace("message read failed: %d\n", status);
                break;
            }

            txn.txid = reinterpret_cast<const fidl_message_header_t*>(msg.bytes)->txid;

            status = fuchsia_hardware_ethertap_TapDevice_dispatch(this,
                                                                  &txn.txn,
                                                                  &msg,
                                                                  &tap_device_ops_);
            if (status != ZX_OK) {
                ethertap_trace("failed to dispatch ethertap message: %d\n", status);
                break;
            }
        }
        if (pending & ZX_CHANNEL_PEER_CLOSED) {
            ethertap_trace("channel closed (peer)\n");
            break;
        }
        if (pending & TAP_SHUTDOWN) {
            ethertap_trace("channel closed (self)\n");
            break;
        }
    }
    {
        fbl::AutoLock lock(&lock_);
        dead_ = true;
        zxlogf(INFO, "ethertap: device '%s' destroyed\n", name());
        channel_.reset();
    }
    DdkRemove();

    return static_cast<int>(status);
}

} // namespace eth

extern "C" zx_status_t tapctl_bind(void* ctx, zx_device_t* device, void** cookie) {
    auto dev = fbl::unique_ptr<eth::TapCtl>(new eth::TapCtl(device));
    zx_status_t status = dev->DdkAdd("tapctl");
    if (status != ZX_OK) {
        zxlogf(ERROR, "%s: could not add device: %d\n", __func__, status);
    } else {
        // devmgr owns the memory now
        __UNUSED auto ptr = dev.release();
    }
    return status;
}