server/TcUtils.h

/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <android-base/result.h>
#include <errno.h>
#include <linux/if_ether.h>
#include <linux/if_link.h>
#include <linux/rtnetlink.h>
#include <tcutils/tcutils.h>

#include <string>

#include "bpf/BpfUtils.h"
#include "bpf_shared.h"

namespace android {
namespace net {

// For better code clarity - do not change values - used for booleans like
// with_ethernet_header or isEthernet.
constexpr bool RAWIP = false;
constexpr bool ETHER = true;

// For better code clarity when used for 'bool ingress' parameter.
constexpr bool EGRESS = false;
constexpr bool INGRESS = true;

// The priority of clat hook - must be after tethering.
constexpr uint16_t PRIO_CLAT = 4;

inline base::Result<bool> isEthernet(const std::string& interface) {
    bool result = false;
    if (int error = ::android::isEthernet(interface.c_str(), result)) {
        errno = error;
        return ErrnoErrorf("isEthernet failed for interface {}", interface);
    }
    return result;
}

inline int getClatEgress4MapFd(void) {
    const int fd = bpf::mapRetrieveRW(CLAT_EGRESS4_MAP_PATH);
    return (fd == -1) ? -errno : fd;
}

inline int getClatIngress6MapFd(void) {
    const int fd = bpf::mapRetrieveRW(CLAT_INGRESS6_MAP_PATH);
    return (fd == -1) ? -errno : fd;
}

inline int tcQdiscAddDevClsact(int ifIndex) {
    return doTcQdiscClsact(ifIndex, RTM_NEWQDISC, NLM_F_EXCL | NLM_F_CREATE);
}

inline int tcQdiscReplaceDevClsact(int ifIndex) {
    return doTcQdiscClsact(ifIndex, RTM_NEWQDISC, NLM_F_CREATE | NLM_F_REPLACE);
}

inline int tcQdiscDelDevClsact(int ifIndex) {
    return doTcQdiscClsact(ifIndex, RTM_DELQDISC, 0);
}

// tc filter add dev .. ingress prio 4 protocol ipv6 bpf object-pinned /sys/fs/bpf/... direct-action
inline int tcFilterAddDevIngressClatIpv6(int ifIndex, const std::string& bpfProgPath) {
    return tcAddBpfFilter(ifIndex, INGRESS, PRIO_CLAT, ETH_P_IPV6, bpfProgPath.c_str());
}

// tc filter add dev .. egress prio 4 protocol ip bpf object-pinned /sys/fs/bpf/... direct-action
inline int tcFilterAddDevEgressClatIpv4(int ifIndex, const std::string& bpfProgPath) {
    return tcAddBpfFilter(ifIndex, EGRESS, PRIO_CLAT, ETH_P_IP, bpfProgPath.c_str());
}

// tc filter del dev .. ingress prio 4 protocol ipv6
inline int tcFilterDelDevIngressClatIpv6(int ifIndex) {
    return tcDeleteFilter(ifIndex, INGRESS, PRIO_CLAT, ETH_P_IPV6);
}

// tc filter del dev .. egress prio 4 protocol ip
inline int tcFilterDelDevEgressClatIpv4(int ifIndex) {
    return tcDeleteFilter(ifIndex, EGRESS, PRIO_CLAT, ETH_P_IP);
}

}  // namespace net
}  // namespace android