platform_system_core/adb/daemon/mdns.cpp
Casey Dahlin 13a269ea24 Add mDNS device discovery for adb client
Test: Was able to discover a raspberry pi.
Bug: 28074466
(cherry picked from e292cd16760321fccc99c8c261cb92fa4b6462ab)

Change-Id: Id9571576457a4a0a078e48a274a4e8eac78bfe2b
2017-03-07 14:45:51 -08:00

95 lines
2.8 KiB
C++

/*
* Copyright (C) 2016 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 "adb_mdns.h"
#include "sysdeps.h"
#include <chrono>
#include <dns_sd.h>
#include <endian.h>
#include <mutex>
#include <unistd.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
using namespace std::chrono_literals;
static std::mutex& mdns_lock = *new std::mutex();
static int port;
static DNSServiceRef mdns_ref;
static bool mdns_registered = false;
static void start_mdns() {
if (android::base::GetProperty("init.svc.mdnsd", "") == "running") {
return;
}
android::base::SetProperty("ctl.start", "mdnsd");
if (! android::base::WaitForProperty("init.svc.mdnsd", "running", 5s)) {
LOG(ERROR) << "Could not start mdnsd.";
}
}
static void mdns_callback(DNSServiceRef /*ref*/,
DNSServiceFlags /*flags*/,
DNSServiceErrorType errorCode,
const char* /*name*/,
const char* /*regtype*/,
const char* /*domain*/,
void* /*context*/) {
if (errorCode != kDNSServiceErr_NoError) {
LOG(ERROR) << "Encountered mDNS registration error ("
<< errorCode << ").";
}
}
static void setup_mdns_thread(void* /* unused */) {
start_mdns();
std::lock_guard<std::mutex> lock(mdns_lock);
std::string hostname = "adb-";
hostname += android::base::GetProperty("ro.serialno", "unidentified");
auto error = DNSServiceRegister(&mdns_ref, 0, 0, hostname.c_str(),
kADBServiceType, nullptr, nullptr,
htobe16((uint16_t)port), 0, nullptr,
mdns_callback, nullptr);
if (error != kDNSServiceErr_NoError) {
LOG(ERROR) << "Could not register mDNS service (" << error << ").";
mdns_registered = false;
}
mdns_registered = true;
}
static void teardown_mdns() {
std::lock_guard<std::mutex> lock(mdns_lock);
if (mdns_registered) {
DNSServiceRefDeallocate(mdns_ref);
}
}
void setup_mdns(int port_in) {
port = port_in;
adb_thread_create(setup_mdns_thread, nullptr, nullptr);
// TODO: Make this more robust against a hard kill.
atexit(teardown_mdns);
}