/*
 * Copyright (C) 2007 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.
 */

#define TRACE_TAG TRANSPORT

#include "sysdeps.h"
#include "transport.h"

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

#include <condition_variable>
#include <functional>
#include <memory>
#include <mutex>
#include <thread>
#include <unordered_map>
#include <vector>

#include <android-base/parsenetaddress.h>
#include <android-base/stringprintf.h>
#include <android-base/thread_annotations.h>
#include <cutils/sockets.h>

#if !ADB_HOST
#include <android-base/properties.h>
#endif

#include "adb.h"
#include "adb_io.h"
#include "adb_unique_fd.h"
#include "adb_utils.h"
#include "socket_spec.h"
#include "sysdeps/chrono.h"

#if ADB_HOST

// Android Wear has been using port 5601 in all of its documentation/tooling,
// but we search for emulators on ports [5554, 5555 + ADB_LOCAL_TRANSPORT_MAX].
// Avoid stomping on their port by limiting the number of emulators that can be
// connected.
#define ADB_LOCAL_TRANSPORT_MAX 16

static std::mutex& local_transports_lock = *new std::mutex();

// We keep a map from emulator port to transport.
// TODO: weak_ptr?
static auto& local_transports GUARDED_BY(local_transports_lock) =
    *new std::unordered_map<int, atransport*>();
#endif /* ADB_HOST */

bool local_connect(int port) {
    std::string dummy;
    return local_connect_arbitrary_ports(port - 1, port, &dummy) == 0;
}

std::tuple<unique_fd, int, std::string> tcp_connect(const std::string& address,
                                                    std::string* response) {
    unique_fd fd;
    int port = DEFAULT_ADB_LOCAL_TRANSPORT_PORT;
    std::string serial;
    std::string prefix_addr = address.starts_with("vsock:") ? address : "tcp:" + address;
    if (socket_spec_connect(&fd, prefix_addr, &port, &serial, response)) {
        close_on_exec(fd);
        if (!set_tcp_keepalive(fd, 1)) {
            D("warning: failed to configure TCP keepalives (%s)", strerror(errno));
        }
        return std::make_tuple(std::move(fd), port, serial);
    }
    return std::make_tuple(unique_fd(), 0, serial);
}

void connect_device(const std::string& address, std::string* response) {
    if (address.empty()) {
        *response = "empty address";
        return;
    }

    D("connection requested to '%s'", address.c_str());
    unique_fd fd;
    int port;
    std::string serial;
    std::tie(fd, port, serial) = tcp_connect(address, response);
    if (fd.get() == -1) {
        return;
    }
    auto reconnect = [address](atransport* t) {
        std::string response;
        unique_fd fd;
        int port;
        std::string serial;
        std::tie(fd, port, serial) = tcp_connect(address, &response);
        if (fd == -1) {
            D("reconnect failed: %s", response.c_str());
            return ReconnectResult::Retry;
        }

        // This invokes the part of register_socket_transport() that needs to be
        // invoked if the atransport* has already been setup. This eventually
        // calls atransport->SetConnection() with a newly created Connection*
        // that will in turn send the CNXN packet.
        return init_socket_transport(t, std::move(fd), port, 0) >= 0 ? ReconnectResult::Success
                                                                     : ReconnectResult::Retry;
    };

    int error;
    if (!register_socket_transport(std::move(fd), serial, port, 0, std::move(reconnect), &error)) {
        if (error == EALREADY) {
            *response = android::base::StringPrintf("already connected to %s", serial.c_str());
        } else if (error == EPERM) {
            *response = android::base::StringPrintf("failed to authenticate to %s", serial.c_str());
        } else {
            *response = android::base::StringPrintf("failed to connect to %s", serial.c_str());
        }
    } else {
        *response = android::base::StringPrintf("connected to %s", serial.c_str());
    }
}


int local_connect_arbitrary_ports(int console_port, int adb_port, std::string* error) {
    unique_fd fd;

#if ADB_HOST
    if (find_emulator_transport_by_adb_port(adb_port) != nullptr ||
        find_emulator_transport_by_console_port(console_port) != nullptr) {
        return -1;
    }

    const char *host = getenv("ADBHOST");
    if (host) {
        fd.reset(network_connect(host, adb_port, SOCK_STREAM, 0, error));
    }
#endif
    if (fd < 0) {
        fd.reset(network_loopback_client(adb_port, SOCK_STREAM, error));
    }

    if (fd >= 0) {
        D("client: connected on remote on fd %d", fd.get());
        close_on_exec(fd.get());
        disable_tcp_nagle(fd.get());
        std::string serial = getEmulatorSerialString(console_port);
        if (register_socket_transport(std::move(fd), std::move(serial), adb_port, 1,
                                      [](atransport*) { return ReconnectResult::Abort; })) {
            return 0;
        }
    }
    return -1;
}

#if ADB_HOST

static void PollAllLocalPortsForEmulator() {
    int port = DEFAULT_ADB_LOCAL_TRANSPORT_PORT;
    int count = ADB_LOCAL_TRANSPORT_MAX;

    // Try to connect to any number of running emulator instances.
    for ( ; count > 0; count--, port += 2 ) {
        local_connect(port);
    }
}

// Retry the disconnected local port for 60 times, and sleep 1 second between two retries.
static constexpr uint32_t LOCAL_PORT_RETRY_COUNT = 60;
static constexpr auto LOCAL_PORT_RETRY_INTERVAL = 1s;

struct RetryPort {
    int port;
    uint32_t retry_count;
};

// Retry emulators just kicked.
static std::vector<RetryPort>& retry_ports = *new std::vector<RetryPort>;
std::mutex &retry_ports_lock = *new std::mutex;
std::condition_variable &retry_ports_cond = *new std::condition_variable;

static void client_socket_thread(int) {
    adb_thread_setname("client_socket_thread");
    D("transport: client_socket_thread() starting");
    PollAllLocalPortsForEmulator();
    while (true) {
        std::vector<RetryPort> ports;
        // Collect retry ports.
        {
            std::unique_lock<std::mutex> lock(retry_ports_lock);
            while (retry_ports.empty()) {
                retry_ports_cond.wait(lock);
            }
            retry_ports.swap(ports);
        }
        // Sleep here instead of the end of loop, because if we immediately try to reconnect
        // the emulator just kicked, the adbd on the emulator may not have time to remove the
        // just kicked transport.
        std::this_thread::sleep_for(LOCAL_PORT_RETRY_INTERVAL);

        // Try connecting retry ports.
        std::vector<RetryPort> next_ports;
        for (auto& port : ports) {
            VLOG(TRANSPORT) << "retry port " << port.port << ", last retry_count "
                << port.retry_count;
            if (local_connect(port.port)) {
                VLOG(TRANSPORT) << "retry port " << port.port << " successfully";
                continue;
            }
            if (--port.retry_count > 0) {
                next_ports.push_back(port);
            } else {
                VLOG(TRANSPORT) << "stop retrying port " << port.port;
            }
        }

        // Copy back left retry ports.
        {
            std::unique_lock<std::mutex> lock(retry_ports_lock);
            retry_ports.insert(retry_ports.end(), next_ports.begin(), next_ports.end());
        }
    }
}

#else  // !ADB_HOST

void server_socket_thread(std::string_view spec) {
    unique_fd serverfd;

    adb_thread_setname("server socket");
    D("transport: server_socket_thread() starting");
    int port;
    while (serverfd == -1) {
        std::string error;
        errno = 0;
        serverfd.reset(socket_spec_listen(spec, &error, &port));
        if (errno == EAFNOSUPPORT || errno == EINVAL || errno == EPROTONOSUPPORT) {
            D("unrecoverable error: '%s'", error.c_str());
            return;
        } else if (serverfd < 0) {
            D("server: cannot bind socket yet: %s", error.c_str());
            std::this_thread::sleep_for(1s);
            continue;
        }
        close_on_exec(serverfd.get());
    }

    while (true) {
        std::string spec_str{spec};
        D("server: trying to get new connection from %s", spec_str.c_str());
        unique_fd fd(adb_socket_accept(serverfd, nullptr, nullptr));
        if (fd >= 0) {
            D("server: new connection on fd %d", fd.get());
            close_on_exec(fd.get());
            disable_tcp_nagle(fd.get());
            std::string serial = android::base::StringPrintf("host-%d", fd.get());
            register_socket_transport(std::move(fd), std::move(serial), port, 1,
                                      [](atransport*) { return ReconnectResult::Abort; });
        }
    }
    D("transport: server_socket_thread() exiting");
}

#endif

void local_init(int port) {
#if ADB_HOST
    D("transport: local client init");
    std::thread(client_socket_thread, port).detach();
#elif !defined(__ANDROID__)
    // Host adbd.
    D("transport: local server init");
    std::thread(server_socket_thread, android::base::StringPrintf("tcp:%d", port)).detach();
    std::thread(server_socket_thread, android::base::StringPrintf("vsock:%d", port)).detach();
#else
    D("transport: local server init");
    // For the adbd daemon in the system image we need to distinguish
    // between the device, and the emulator.
    if (use_qemu_goldfish()) {
        std::thread(qemu_socket_thread, port).detach();
    } else {
        std::thread(server_socket_thread, android::base::StringPrintf("tcp:%d", port)).detach();
    }
    std::thread(server_socket_thread, android::base::StringPrintf("vsock:%d", port)).detach();
#endif // !ADB_HOST
}

#if ADB_HOST
struct EmulatorConnection : public FdConnection {
    EmulatorConnection(unique_fd fd, int local_port)
        : FdConnection(std::move(fd)), local_port_(local_port) {}

    ~EmulatorConnection() {
        VLOG(TRANSPORT) << "remote_close, local_port = " << local_port_;
        std::unique_lock<std::mutex> lock(retry_ports_lock);
        RetryPort port;
        port.port = local_port_;
        port.retry_count = LOCAL_PORT_RETRY_COUNT;
        retry_ports.push_back(port);
        retry_ports_cond.notify_one();
    }

    void Close() override {
        std::lock_guard<std::mutex> lock(local_transports_lock);
        local_transports.erase(local_port_);
        FdConnection::Close();
    }

    int local_port_;
};

/* Only call this function if you already hold local_transports_lock. */
static atransport* find_emulator_transport_by_adb_port_locked(int adb_port)
    REQUIRES(local_transports_lock) {
    auto it = local_transports.find(adb_port);
    if (it == local_transports.end()) {
        return nullptr;
    }
    return it->second;
}

atransport* find_emulator_transport_by_adb_port(int adb_port) {
    std::lock_guard<std::mutex> lock(local_transports_lock);
    return find_emulator_transport_by_adb_port_locked(adb_port);
}

atransport* find_emulator_transport_by_console_port(int console_port) {
    return find_transport(getEmulatorSerialString(console_port).c_str());
}
#endif

std::string getEmulatorSerialString(int console_port) {
    return android::base::StringPrintf("emulator-%d", console_port);
}

int init_socket_transport(atransport* t, unique_fd fd, int adb_port, int local) {
    int fail = 0;

    t->type = kTransportLocal;

#if ADB_HOST
    // Emulator connection.
    if (local) {
        auto emulator_connection = std::make_unique<EmulatorConnection>(std::move(fd), adb_port);
        t->SetConnection(
            std::make_unique<BlockingConnectionAdapter>(std::move(emulator_connection)));
        std::lock_guard<std::mutex> lock(local_transports_lock);
        atransport* existing_transport = find_emulator_transport_by_adb_port_locked(adb_port);
        if (existing_transport != nullptr) {
            D("local transport for port %d already registered (%p)?", adb_port, existing_transport);
            fail = -1;
        } else if (local_transports.size() >= ADB_LOCAL_TRANSPORT_MAX) {
            // Too many emulators.
            D("cannot register more emulators. Maximum is %d", ADB_LOCAL_TRANSPORT_MAX);
            fail = -1;
        } else {
            local_transports[adb_port] = t;
        }

        return fail;
    }
#endif

    // Regular tcp connection.
    auto fd_connection = std::make_unique<FdConnection>(std::move(fd));
    t->SetConnection(std::make_unique<BlockingConnectionAdapter>(std::move(fd_connection)));
    return fail;
}
