lib/wlan/mlme/tests/test_bss.cpp

// Copyright 2018 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 "test_bss.h"
#include "mock_device.h"

#include <wlan/common/buffer_writer.h>
#include <wlan/common/channel.h>
#include <wlan/common/write_element.h>
#include <wlan/mlme/ap/bss_interface.h>
#include <wlan/mlme/debug.h>
#include <wlan/mlme/mac_frame.h>
#include <wlan/mlme/packet.h>
#include <wlan/mlme/rates_elements.h>
#include <wlan/mlme/service.h>

#include <fbl/unique_ptr.h>
#include <fuchsia/wlan/mlme/c/fidl.h>
#include <fuchsia/wlan/mlme/cpp/fidl.h>

#include <gtest/gtest.h>

namespace wlan {

namespace wlan_mlme = ::fuchsia::wlan::mlme;

void WriteTim(BufferWriter* w, const PsCfg& ps_cfg) {
    size_t bitmap_len = ps_cfg.GetTim()->BitmapLen();
    uint8_t bitmap_offset = ps_cfg.GetTim()->BitmapOffset();

    TimHeader hdr;
    hdr.dtim_count = ps_cfg.dtim_count();
    hdr.dtim_period = ps_cfg.dtim_period();
    ZX_DEBUG_ASSERT(hdr.dtim_count != hdr.dtim_period);
    if (hdr.dtim_count == hdr.dtim_period) { warnf("illegal DTIM state"); }

    hdr.bmp_ctrl.set_offset(bitmap_offset);
    if (ps_cfg.IsDtim()) { hdr.bmp_ctrl.set_group_traffic_ind(ps_cfg.GetTim()->HasGroupTraffic()); }
    common::WriteTim(w, hdr, {ps_cfg.GetTim()->BitmapData(), bitmap_len});
}

void WriteCountry(BufferWriter* w, const wlan_channel_t chan) {
    const Country kCountry = {{'U', 'S', ' '}};

    std::vector<SubbandTriplet> subbands;

    // TODO(porce): Read from the AP's regulatory domain
    if (wlan::common::Is2Ghz(chan)) {
        subbands.push_back({1, 11, 36});
    } else {
        subbands.push_back({36, 4, 36});
        subbands.push_back({52, 4, 30});
        subbands.push_back({100, 12, 30});
        subbands.push_back({149, 5, 36});
    }

    common::WriteCountry(w, kCountry, subbands);
}

wlan_mlme::BSSDescription CreateBssDescription(bool rsn, wlan_channel_t chan) {
    common::MacAddr bssid(kBssid1);

    wlan_mlme::BSSDescription bss_desc;
    std::memcpy(bss_desc.bssid.mutable_data(), bssid.byte, common::kMacAddrLen);
    std::vector<uint8_t> ssid(kSsid, kSsid + sizeof(kSsid));
    bss_desc.ssid.reset(std::move(ssid));
    bss_desc.bss_type = wlan_mlme::BSSTypes::INFRASTRUCTURE;
    bss_desc.beacon_period = kBeaconPeriodTu;
    bss_desc.dtim_period = kDtimPeriodTu;
    bss_desc.timestamp = 0;
    bss_desc.local_time = 0;
    bss_desc.basic_rate_set.resize(0);
    bss_desc.op_rate_set.resize(0);

    wlan_mlme::CapabilityInfo cap;
    cap.ess = true;
    cap.short_preamble = true;
    bss_desc.cap = cap;

    if (rsn) {
        bss_desc.rsn.reset(std::vector<uint8_t>(kRsne, kRsne + sizeof(kRsne)));
    } else {
        bss_desc.rsn.reset();
    }
    bss_desc.rcpi_dbmh = 0;
    bss_desc.rsni_dbh = 0;

    bss_desc.ht_cap.reset();
    bss_desc.ht_op.reset();

    bss_desc.vht_cap.reset();
    bss_desc.vht_op.reset();

    bss_desc.chan.cbw = static_cast<wlan_mlme::CBW>(chan.cbw);
    bss_desc.chan.primary = chan.primary;

    bss_desc.rssi_dbm = -35;

    return bss_desc;
}

MlmeMsg<wlan_mlme::ScanRequest> CreateScanRequest(uint32_t max_channel_time) {
    auto req = wlan_mlme::ScanRequest::New();
    req->txn_id = 0;
    req->bss_type = wlan_mlme::BSSTypes::ANY_BSS;
    std::memcpy(req->bssid.mutable_data(), kBroadcastBssid, sizeof(kBroadcastBssid));
    req->ssid.reset({0});
    req->scan_type = wlan_mlme::ScanTypes::PASSIVE;
    req->channel_list.reset({11});
    req->max_channel_time = max_channel_time;

    return {std::move(*req), fuchsia_wlan_mlme_MLMEStartScanOrdinal};
}

MlmeMsg<wlan_mlme::StartRequest> CreateStartRequest(bool protected_ap) {
    auto req = wlan_mlme::StartRequest::New();
    std::vector<uint8_t> ssid(kSsid, kSsid + sizeof(kSsid));
    req->ssid.reset(std::move(ssid));
    req->bss_type = wlan_mlme::BSSTypes::INFRASTRUCTURE;
    req->beacon_period = kBeaconPeriodTu;
    req->dtim_period = kDtimPeriodTu;
    req->channel = kBssChannel.primary;
    req->mesh_id.resize(0);
    if (protected_ap) { req->rsne.reset(std::vector<uint8_t>(kRsne, kRsne + sizeof(kRsne))); }

    return {std::move(*req), fuchsia_wlan_mlme_MLMEStartReqOrdinal};
}

MlmeMsg<wlan_mlme::JoinRequest> CreateJoinRequest(bool rsn) {
    auto req = wlan_mlme::JoinRequest::New();
    req->join_failure_timeout = kJoinTimeout;
    req->nav_sync_delay = 20;
    req->op_rate_set.reset({12, 24, 48});
    req->phy = wlan_mlme::PHY::HR;
    req->cbw = wlan_mlme::CBW::CBW20;
    req->selected_bss = CreateBssDescription(rsn);
    req->selected_bss.op_rate_set.reset({12, 24, 48});

    return {std::move(*req), fuchsia_wlan_mlme_MLMEJoinReqOrdinal};
}

MlmeMsg<wlan_mlme::AuthenticateRequest> CreateAuthRequest() {
    common::MacAddr bssid(kBssid1);

    auto req = wlan_mlme::AuthenticateRequest::New();
    std::memcpy(req->peer_sta_address.mutable_data(), bssid.byte, common::kMacAddrLen);
    req->auth_failure_timeout = kAuthTimeout;
    req->auth_type = wlan_mlme::AuthenticationTypes::OPEN_SYSTEM;

    return {std::move(*req), fuchsia_wlan_mlme_MLMEAuthenticateReqOrdinal};
}

MlmeMsg<wlan_mlme::DeauthenticateRequest> CreateDeauthRequest(common::MacAddr peer_addr,
                                                              wlan_mlme::ReasonCode reason_code) {
    auto req = wlan_mlme::DeauthenticateRequest::New();
    std::memcpy(req->peer_sta_address.mutable_data(), peer_addr.byte, common::kMacAddrLen);
    req->reason_code = reason_code;
    return {std::move(*req), fuchsia_wlan_mlme_MLMEDeauthenticateReqOrdinal};
}

MlmeMsg<wlan_mlme::AuthenticateResponse> CreateAuthResponse(
    common::MacAddr client_addr, wlan_mlme::AuthenticateResultCodes result_code) {
    auto resp = wlan_mlme::AuthenticateResponse::New();
    std::memcpy(resp->peer_sta_address.mutable_data(), client_addr.byte, common::kMacAddrLen);
    resp->result_code = result_code;

    return {std::move(*resp), fuchsia_wlan_mlme_MLMEAuthenticateRespOrdinal};
}

MlmeMsg<wlan_mlme::AssociateRequest> CreateAssocRequest(bool rsn) {
    common::MacAddr bssid(kBssid1);

    auto req = wlan_mlme::AssociateRequest::New();
    std::memcpy(req->peer_sta_address.mutable_data(), bssid.byte, common::kMacAddrLen);
    if (rsn) {
        req->rsn.reset(std::vector<uint8_t>(kRsne, kRsne + sizeof(kRsne)));
    } else {
        req->rsn.reset();
    }

    return {std::move(*req), fuchsia_wlan_mlme_MLMEAssociateReqOrdinal};
}

MlmeMsg<wlan_mlme::AssociateResponse> CreateAssocResponse(
    common::MacAddr client_addr, wlan_mlme::AssociateResultCodes result_code, uint16_t aid) {
    auto resp = wlan_mlme::AssociateResponse::New();
    std::memcpy(resp->peer_sta_address.mutable_data(), client_addr.byte, common::kMacAddrLen);
    resp->result_code = result_code;
    resp->association_id = aid;

    return {std::move(*resp), fuchsia_wlan_mlme_MLMEAssociateRespOrdinal};
}

MlmeMsg<wlan_mlme::EapolRequest> CreateEapolRequest(common::MacAddr src_addr,
                                                    common::MacAddr dst_addr) {
    auto req = wlan_mlme::EapolRequest::New();
    std::memcpy(req->src_addr.mutable_data(), src_addr.byte, common::kMacAddrLen);
    std::memcpy(req->dst_addr.mutable_data(), dst_addr.byte, common::kMacAddrLen);
    std::vector<uint8_t> eapol_pdu(kEapolPdu, kEapolPdu + sizeof(kEapolPdu));
    req->data.reset(std::move(eapol_pdu));

    return {std::move(*req), fuchsia_wlan_mlme_MLMEEapolReqOrdinal};
}

MlmeMsg<wlan_mlme::SetKeysRequest> CreateSetKeysRequest(common::MacAddr addr,
                                                        std::vector<uint8_t> key_data,
                                                        wlan_mlme::KeyType key_type) {
    wlan_mlme::SetKeyDescriptor key;
    key.key.reset(key_data);
    key.key_id = 1;
    key.key_type = key_type;
    std::memcpy(key.address.mutable_data(), addr.byte, sizeof(addr));
    std::memcpy(key.cipher_suite_oui.mutable_data(), kCipherOui, sizeof(kCipherOui));
    key.cipher_suite_type = kCipherSuiteType;

    std::vector<wlan_mlme::SetKeyDescriptor> keylist;
    keylist.emplace_back(std::move(key));
    auto req = wlan_mlme::SetKeysRequest::New();
    req->keylist.reset(std::move(keylist));

    return {std::move(*req), fuchsia_wlan_mlme_MLMESetKeysReqOrdinal};
}

fbl::unique_ptr<Packet> CreateBeaconFrame(common::MacAddr bssid) {
    constexpr size_t ie_len = 256;
    constexpr size_t max_frame_len = MgmtFrameHeader::max_len() + Beacon::max_len() + ie_len;
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kBeacon);
    mgmt_hdr->addr1 = common::kBcastMac;
    mgmt_hdr->addr2 = bssid;
    mgmt_hdr->addr3 = bssid;

    auto bcn = w.Write<Beacon>();
    bcn->beacon_interval = kBeaconPeriodTu;
    bcn->timestamp = 0;
    bcn->cap.set_ess(1);
    bcn->cap.set_short_preamble(1);

    BufferWriter elem_w(w.RemainingBuffer());
    common::WriteSsid(&elem_w, kSsid);
    RatesWriter rates_writer{kSupportedRates};
    rates_writer.WriteSupportedRates(&elem_w);
    common::WriteDsssParamSet(&elem_w, kBssChannel.primary);
    WriteCountry(&elem_w, kBssChannel);
    rates_writer.WriteExtendedSupportedRates(&elem_w);

    packet->set_len(w.WrittenBytes() + elem_w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}

fbl::unique_ptr<Packet> CreateProbeRequest() {
    common::MacAddr bssid(kBssid1);
    common::MacAddr client(kClientAddress);

    constexpr size_t ie_len = 256;
    constexpr size_t max_frame_len = MgmtFrameHeader::max_len() + ProbeRequest::max_len() + ie_len;
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kBeacon);
    mgmt_hdr->addr1 = client;
    mgmt_hdr->addr2 = bssid;
    mgmt_hdr->addr3 = bssid;

    w.Write<ProbeRequest>();
    BufferWriter elem_w(w.RemainingBuffer());
    common::WriteSsid(&elem_w, kSsid);

    RatesWriter rates_writer{kSupportedRates};
    rates_writer.WriteSupportedRates(&elem_w);
    rates_writer.WriteExtendedSupportedRates(&elem_w);
    common::WriteDsssParamSet(&elem_w, kBssChannel.primary);

    packet->set_len(w.WrittenBytes() + elem_w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}

fbl::unique_ptr<Packet> CreateAuthReqFrame(common::MacAddr client_addr) {
    common::MacAddr bssid(kBssid1);
    constexpr size_t max_frame_len = MgmtFrameHeader::max_len() + Authentication::max_len();
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kAuthentication);
    mgmt_hdr->addr1 = bssid;
    mgmt_hdr->addr2 = client_addr;
    mgmt_hdr->addr3 = bssid;

    auto auth = w.Write<Authentication>();
    auth->auth_algorithm_number = AuthAlgorithm::kOpenSystem;
    auth->auth_txn_seq_number = 1;
    auth->status_code = 0;  // Reserved: explicitly set to 0

    packet->set_len(w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}

fbl::unique_ptr<Packet> CreateAuthRespFrame(AuthAlgorithm auth_algo) {
    common::MacAddr bssid(kBssid1);
    common::MacAddr client(kClientAddress);

    constexpr size_t max_frame_len = MgmtFrameHeader::max_len() + Authentication::max_len();
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kAuthentication);
    mgmt_hdr->addr1 = client;
    mgmt_hdr->addr2 = bssid;
    mgmt_hdr->addr3 = bssid;

    auto auth = w.Write<Authentication>();
    auth->auth_algorithm_number = auth_algo;
    auth->auth_txn_seq_number = 2;
    auth->status_code = status_code::kSuccess;

    packet->set_len(w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}

fbl::unique_ptr<Packet> CreateDeauthFrame(common::MacAddr client_addr) {
    common::MacAddr bssid(kBssid1);

    constexpr size_t max_frame_len = MgmtFrameHeader::max_len() + Deauthentication::max_len();
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kDeauthentication);
    mgmt_hdr->addr1 = bssid;
    mgmt_hdr->addr2 = client_addr;
    mgmt_hdr->addr3 = bssid;

    w.Write<Deauthentication>()->reason_code = reason_code::ReasonCode::kLeavingNetworkDeauth;

    packet->set_len(w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}

fbl::unique_ptr<Packet> CreateAssocReqFrame(common::MacAddr client_addr, Span<const uint8_t> ssid,
                                            bool rsn) {
    common::MacAddr bssid(kBssid1);

    // arbitrarily large reserved len; will shrink down later
    constexpr size_t ie_len = 1024;
    constexpr size_t max_frame_len =
        MgmtFrameHeader::max_len() + AssociationRequest::max_len() + ie_len;
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kAssociationRequest);
    mgmt_hdr->addr1 = bssid;
    mgmt_hdr->addr2 = client_addr;
    mgmt_hdr->addr3 = bssid;

    auto assoc = w.Write<AssociationRequest>();
    CapabilityInfo cap = {};
    cap.set_short_preamble(1);
    cap.set_ess(1);
    assoc->cap = cap;
    assoc->listen_interval = kListenInterval;

    BufferWriter elem_w(w.RemainingBuffer());
    if (!ssid.empty()) { common::WriteSsid(&w, ssid); }
    if (rsn) { w.Write(kRsne); }

    packet->set_len(w.WrittenBytes() + elem_w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}

fbl::unique_ptr<Packet> CreateAssocRespFrame(const AssocContext& ap_assoc_ctx) {
    common::MacAddr bssid(kBssid1);
    common::MacAddr client(kClientAddress);

    constexpr size_t reserved_ie_len = 256;
    constexpr size_t max_frame_len =
        MgmtFrameHeader::max_len() + AssociationResponse::max_len() + reserved_ie_len;
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    // TODO(NET-2007): Implement a common frame builder
    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kAssociationResponse);
    mgmt_hdr->addr1 = client;
    mgmt_hdr->addr2 = bssid;
    mgmt_hdr->addr3 = bssid;

    auto assoc = w.Write<AssociationResponse>();
    assoc->aid = kAid;
    CapabilityInfo cap = {};
    cap.set_short_preamble(1);
    cap.set_ess(1);
    assoc->cap = cap;
    assoc->status_code = status_code::kSuccess;

    BufferWriter elem_w(w.RemainingBuffer());
    if (ap_assoc_ctx.ht_cap.has_value()) {
        common::WriteHtCapabilities(&elem_w, ap_assoc_ctx.ht_cap.value());
    }
    if (ap_assoc_ctx.ht_op.has_value()) {
        common::WriteHtOperation(&elem_w, ap_assoc_ctx.ht_op.value());
    }
    if (ap_assoc_ctx.vht_cap.has_value()) {
        common::WriteVhtCapabilities(&elem_w, ap_assoc_ctx.vht_cap.value());
    }
    if (ap_assoc_ctx.vht_op.has_value()) {
        common::WriteVhtOperation(&elem_w, ap_assoc_ctx.vht_op.value());
    }

    packet->set_len(w.WrittenBytes() + elem_w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}
fbl::unique_ptr<Packet> CreateDisassocFrame(common::MacAddr client_addr) {
    common::MacAddr bssid(kBssid1);

    constexpr size_t max_frame_len = MgmtFrameHeader::max_len() + Disassociation::max_len();
    auto packet = GetWlanPacket(max_frame_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto mgmt_hdr = w.Write<MgmtFrameHeader>();
    mgmt_hdr->fc.set_type(FrameType::kManagement);
    mgmt_hdr->fc.set_subtype(ManagementSubtype::kDisassociation);
    mgmt_hdr->addr1 = bssid;
    mgmt_hdr->addr2 = client_addr;
    mgmt_hdr->addr3 = bssid;

    w.Write<Disassociation>()->reason_code = reason_code::ReasonCode::kLeavingNetworkDisassoc;

    packet->set_len(w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return packet;
}

DataFrame<LlcHeader> CreateDataFrame(const uint8_t* payload, size_t len) {
    common::MacAddr bssid(kBssid1);
    common::MacAddr client(kClientAddress);

    const size_t buf_len = DataFrameHeader::max_len() + LlcHeader::max_len() + len;
    auto packet = GetWlanPacket(buf_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto data_hdr = w.Write<DataFrameHeader>();
    data_hdr->fc.set_type(FrameType::kData);
    data_hdr->fc.set_subtype(DataSubtype::kDataSubtype);
    data_hdr->fc.set_from_ds(1);
    data_hdr->addr1 = bssid;
    data_hdr->addr2 = bssid;
    data_hdr->addr3 = client;
    data_hdr->sc.set_val(42);

    auto llc_hdr = w.Write<LlcHeader>();
    llc_hdr->dsap = kLlcSnapExtension;
    llc_hdr->ssap = kLlcSnapExtension;
    llc_hdr->control = kLlcUnnumberedInformation;
    std::memcpy(llc_hdr->oui, kLlcOui, sizeof(llc_hdr->oui));
    llc_hdr->protocol_id = 42;
    if (len > 0) { w.Write({payload, len}); }

    packet->set_len(w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return DataFrame<LlcHeader>(std::move(packet));
}

DataFrame<> CreateNullDataFrame() {
    common::MacAddr bssid(kBssid1);
    common::MacAddr client(kClientAddress);

    auto packet = GetWlanPacket(DataFrameHeader::max_len());
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto data_hdr = w.Write<DataFrameHeader>();
    data_hdr->fc.set_type(FrameType::kData);
    data_hdr->fc.set_subtype(DataSubtype::kNull);
    data_hdr->fc.set_from_ds(1);
    data_hdr->addr1 = client;
    data_hdr->addr2 = bssid;
    data_hdr->addr3 = bssid;
    data_hdr->sc.set_val(42);

    packet->set_len(w.WrittenBytes());

    wlan_rx_info_t rx_info{.rx_flags = 0};
    packet->CopyCtrlFrom(rx_info);

    return DataFrame<>(std::move(packet));
}

EthFrame CreateEthFrame(const uint8_t* payload, size_t len) {
    common::MacAddr bssid(kBssid1);
    common::MacAddr client(kClientAddress);

    size_t buf_len = EthernetII::max_len() + len;
    auto packet = GetEthPacket(buf_len);
    ZX_DEBUG_ASSERT(packet != nullptr);

    BufferWriter w(*packet);
    auto eth_hdr = w.Write<EthernetII>();
    eth_hdr->src = client;
    eth_hdr->dest = bssid;
    eth_hdr->ether_type = 2;
    w.Write({payload, len});

    return EthFrame(std::move(packet));
}

}  // namespace wlan