mirror of
https://github.com/ProtonMail/proton-bridge.git
synced 2025-12-15 14:56:42 +00:00
66 lines
1.6 KiB
Go
66 lines
1.6 KiB
Go
// Copyright (c) 2020 Proton Technologies AG
|
|
//
|
|
// This file is part of ProtonMail Bridge.
|
|
//
|
|
// ProtonMail Bridge 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.
|
|
//
|
|
// ProtonMail Bridge 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 ProtonMail Bridge. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
package ports
|
|
|
|
import (
|
|
"net"
|
|
"strconv"
|
|
)
|
|
|
|
const (
|
|
maxPortNumber = 65535
|
|
)
|
|
|
|
// IsPortFree checks if the port is free to use.
|
|
func IsPortFree(port int) bool {
|
|
if !(0 < port && port < maxPortNumber) {
|
|
return false
|
|
}
|
|
stringPort := ":" + strconv.Itoa(port)
|
|
isFree := !isOccupied(stringPort)
|
|
return isFree
|
|
}
|
|
|
|
func isOccupied(port string) bool {
|
|
// Try to create server at port.
|
|
dummyserver, err := net.Listen("tcp", port)
|
|
if err != nil {
|
|
return true
|
|
}
|
|
_ = dummyserver.Close()
|
|
return false
|
|
}
|
|
|
|
// FindFreePortFrom finds first empty port, starting with `startPort`.
|
|
func FindFreePortFrom(startPort int) int {
|
|
loopedOnce := false
|
|
freePort := startPort
|
|
for !IsPortFree(freePort) {
|
|
freePort++
|
|
if freePort >= maxPortNumber {
|
|
freePort = 1
|
|
if loopedOnce {
|
|
freePort = startPort
|
|
break
|
|
}
|
|
loopedOnce = true
|
|
}
|
|
}
|
|
return freePort
|
|
}
|