DnsResolver.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 "DnsResolver.h"

#include <android-base/logging.h>
#include <android-base/properties.h>

#include <resolv.h>
#include "DnsProxyListener.h"
#include "DnsResolverService.h"
#include "resolv_private.h"

bool resolv_init(const ResolverNetdCallbacks& callbacks) {
    android::base::InitLogging(/*argv=*/nullptr);
    android::base::SetDefaultTag("libnetd_resolv");
    LOG(INFO) << __func__ << "Initializing resolver";
    const std::string logSeverityStr =
            android::base::GetProperty("persist.sys.nw_dns_resolver_log", "WARNING");
    android::base::SetMinimumLogSeverity(logSeverityStrToEnum(logSeverityStr));

    android::net::gResNetdCallbacks = callbacks;
    android::net::gDnsResolv = android::net::DnsResolver::getInstance();
    return android::net::gDnsResolv->start();
}

namespace android {
namespace net {

namespace {

bool verifyCallbacks() {
    return gResNetdCallbacks.check_calling_permission && gResNetdCallbacks.get_network_context &&
           gResNetdCallbacks.log;
}

}  // namespace

DnsResolver* gDnsResolv = nullptr;
ResolverNetdCallbacks gResNetdCallbacks;

DnsResolver* DnsResolver::getInstance() {
    // Instantiated on first use.
    static DnsResolver instance;
    return &instance;
}

bool DnsResolver::start() {
    if (!verifyCallbacks()) {
        LOG(ERROR) << __func__ << "Callback verification failed";
        return false;
    }
    if (mDnsProxyListener.startListener()) {
        PLOG(ERROR) << __func__ << "Unable to start DnsProxyListener";
        return false;
    }
    binder_status_t ret;
    if ((ret = DnsResolverService::start()) != STATUS_OK) {
        LOG(ERROR) << __func__ << "Unable to start DnsResolverService: " << ret;
        return false;
    }
    return true;
}

}  // namespace net
}  // namespace android