/*
 * 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 "sysdeps.h"

bool set_tcp_keepalive(borrowed_fd fd, int interval_sec) {
    int enable = (interval_sec > 0);
    if (adb_setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &enable, sizeof(enable))) {
        return false;
    }

    if (!enable) {
        return true;
    }

    // Idle time before sending the first keepalive is TCP_KEEPIDLE on Linux, TCP_KEEPALIVE on Mac.
#if defined(TCP_KEEPIDLE)
    if (adb_setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, &interval_sec, sizeof(interval_sec))) {
        return false;
    }
#elif defined(TCP_KEEPALIVE)
    if (adb_setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE, &interval_sec, sizeof(interval_sec))) {
        return false;
    }
#endif

    // TCP_KEEPINTVL and TCP_KEEPCNT are available on Linux 2.4+ and OS X 10.8+ (Mountain Lion).
#if defined(TCP_KEEPINTVL)
    if (adb_setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, &interval_sec, sizeof(interval_sec))) {
        return false;
    }
#endif

#if defined(TCP_KEEPCNT)
    // On Windows this value is hardcoded to 10. This is a reasonable value, so we do the same here
    // to match behavior. See SO_KEEPALIVE documentation at
    // https://msdn.microsoft.com/en-us/library/windows/desktop/ee470551(v=vs.85).aspx.
    const int keepcnt = 10;
    if (adb_setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, &keepcnt, sizeof(keepcnt))) {
        return false;
    }
#endif

    return true;
}