Zabbix

/*

** Copyright (C) 2001-2025 Zabbix SIA

**

** This program is free software: you can redistribute it and/or modify it under the terms of

** the GNU Affero General Public License as published by the Free Software Foundation, version 3.

**

** 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 Affero General Public License for more details.

**

** You should have received a copy of the GNU Affero General Public License along with this program.

** If not, see <https://www.gnu.org/licenses/>.

**/

​

package zbxcomms

​

import (

    "context"

    "fmt"

    "net"

    "syscall"

​

    "golang.zabbix.com/agent2/pkg/tls"

)

​

func Listen(address string, args ...interface{}) (c *Listener, err error) {

    var tlsconfig *tls.Config

​

    if len(args) > 0 {

        var ok bool

        if tlsconfig, ok = args[0].(*tls.Config); !ok {

            return nil, fmt.Errorf("invalid TLS configuration parameter of type %T", args[0])

        }

    }

​

    // prevent other processes from binding to the same port

    // SO_EXCLUSIVEADDRUSE is mutually exclusive with SO_REUSEADDR

    // on Windows SO_REUSEADDR has different semantics than on Unix

    // https://msdn.microsoft.com/en-us/library/windows/desktop/ms740621(v=vs.85).aspx

    lc := net.ListenConfig{

        Control: func(network, address string, conn syscall.RawConn) error {

            var operr error

            if err := conn.Control(func(fd uintptr) {

                operr = syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, ^syscall.SO_REUSEADDR, 1)

            }); err != nil {

                return err

            }

            return operr

        },

    }

​

    l, tmperr := lc.Listen(context.Background(), "tcp", address)

    if tmperr != nil {

        return nil, fmt.Errorf("Listen failed: %s", tmperr.Error())

    }

    c = &Listener{listener: l.(*net.TCPListener), tlsconfig: tlsconfig}

​

    return

}