DnsQueryLog.cpp

/*
 * 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.
 *
 */

#include "DnsQueryLog.h"

#include "util.h"

namespace android::net {

namespace {

std::string maskHostname(const std::string& hostname) {
    // Boundary issue is handled in substr().
    return hostname.substr(0, 1) + "***";
}

// Return the string of masked addresses of the first v4 address and the first v6 address.
std::string maskIps(const std::vector<std::string>& ips) {
    std::string ret;
    bool v4Found = false, v6Found = false;
    for (const auto& ip : ips) {
        if (auto pos = ip.find_first_of(':'); pos != ip.npos && !v6Found) {
            ret += ip.substr(0, pos + 1) + "***, ";
            v6Found = true;
        } else if (auto pos = ip.find_first_of('.'); pos != ip.npos && !v4Found) {
            ret += ip.substr(0, pos + 1) + "***, ";
            v4Found = true;
        }
        if (v6Found && v4Found) break;
    }
    return ret.empty() ? "" : ret.substr(0, ret.length() - 2);
}

}  // namespace

void DnsQueryLog::push(Record&& record) {
    mQueue.push(std::move(record));
}

uint64_t DnsQueryLog::getLogSizeFromSysProp() {
    const uint64_t logSize = android::base::GetUintProperty<uint64_t>(
            "persist.net.dns_query_log_size", kDefaultLogSize);
    return logSize <= kMaxLogSize ? logSize : kDefaultLogSize;
}

void DnsQueryLog::dump(netdutils::DumpWriter& dw) const {
    dw.println("DNS query log:");
    netdutils::ScopedIndent indentStats(dw);

    for (const auto& record : mQueue.copy()) {
        const std::string maskedHostname = maskHostname(record.hostname);
        const std::string maskedIpsStr = maskIps(record.addrs);
        const std::string time = timestampToString(record.timestamp);
        dw.println("time=%s netId=%u uid=%u pid=%d hostname=%s answer=[%s] (%dms)", time.c_str(),
                   record.netId, record.uid, record.pid, maskedHostname.c_str(),
                   maskedIpsStr.c_str(), record.timeTaken);
    }
}

}  // namespace android::net