// Copyright (C) 2024  mieru authors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package common

import (
	"os"
	"runtime"
	"strings"
)

// TCPCongestionControlAlgorithm returns the TCP congestion control algorithm
// used by the operating system.
func TCPCongestionControlAlgorithm() string {
	if runtime.GOOS == "linux" {
		v, err := os.ReadFile("/proc/sys/net/ipv4/tcp_congestion_control")
		if err != nil {
			return ""
		}
		return strings.TrimSpace(string(v))
	} else {
		// Unsupported platform.
		return ""
	}
}
