Zabbix

/*

** Zabbix

** Copyright (C) 2001-2023 Zabbix SIA

**

** 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 2 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, write to the Free Software

** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

**/

​

package zbxcomms

​

import (

    "bytes"

    "compress/zlib"

    "encoding/binary"

    "errors"

    "fmt"

    "io"

    "net"

    "time"

​

    "git.zabbix.com/ap/plugin-support/log"

    "zabbix.com/pkg/tls"

)

​

const (

    TimeoutModeFixed = iota

    TimeoutModeShift

)

​

const headerSize = 4 + 1 + 4 + 4

const tcpProtocol = byte(0x01)

const zlibCompress = byte(0x02)

​

const (

    connStateAccept = iota + 1

    connStateConnect

    connStateEstablished

)

​

type Connection struct {

    conn        net.Conn

    tlsConfig   *tls.Config

    state       int

    compress    bool

    timeout     time.Duration

    timeoutMode int

}

​

type Listener struct {

    listener  net.Listener

    tlsconfig *tls.Config

}

​

func open(address string, localAddr *net.Addr, timeout time.Duration, connect_timeout time.Duration, timeoutMode int,

    args ...interface{}) (c *Connection, err error) {

    c = &Connection{state: connStateConnect, compress: true, timeout: timeout, timeoutMode: timeoutMode}

    d := net.Dialer{Timeout: connect_timeout, LocalAddr: *localAddr}

    c.conn, err = d.Dial("tcp", address)

​

    if nil != err {

        return

    }

    if err = c.conn.SetDeadline(time.Now().Add(timeout)); err != nil {

        return

    }

    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])

        }

        if tlsconfig != nil {

            c.conn, err = tls.NewClient(c.conn, tlsconfig, timeout, timeoutMode == TimeoutModeShift, address)

        }

    }

    return

}

​

func (c *Connection) write(w io.Writer, data []byte) (err error) {

    var buf bytes.Buffer