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// Copyright (C) 2022 Andrew Ayer
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
// Except as contained in this notice, the name(s) of the above copyright
// holders shall not be used in advertising or otherwise to promote the
// sale, use or other dealings in this Software without prior written
// authorization.
// Package proxy implements version 2 of the PROXY protocol (https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt)
package proxy // import "src.agwa.name/go-listener/proxy"
import (
"errors"
"fmt"
"net"
"sync"
"time"
)
type proxyListener struct {
inner net.Listener
conns chan net.Conn
errors chan error
done chan struct{}
closeMu sync.Mutex
}
// NewListener creates a [net.Listener] which accepts connections from an
// inner net.Listener, reads the PROXY v2 header from the client, and
// sets the local and remote addresses of the [net.Conn] to the values
// specified in the PROXY header.
func NewListener(inner net.Listener) net.Listener {
listener := &proxyListener{
inner: inner,
conns: make(chan net.Conn),
errors: make(chan error),
done: make(chan struct{}),
}
go listener.handleAccepts()
return listener
}
func (listener *proxyListener) Accept() (net.Conn, error) {
select {
case conn := <-listener.conns:
return conn, nil
case err := <-listener.errors:
return nil, err
case <-listener.done:
return nil, net.ErrClosed
}
}
func (listener *proxyListener) Close() error {
listener.closeMu.Lock()
defer listener.closeMu.Unlock()
select {
case <-listener.done:
return net.ErrClosed
default:
close(listener.done)
return listener.inner.Close()
}
}
func (listener *proxyListener) Addr() net.Addr {
return listener.inner.Addr()
}
func (listener *proxyListener) handleAccepts() {
for {
conn, err := listener.inner.Accept()
if errors.Is(err, net.ErrClosed) {
break
} else if err != nil {
if !listener.sendError(err) {
break
}
} else {
go listener.handleConnection(conn)
}
}
}
func (listener *proxyListener) handleConnection(conn net.Conn) {
if err := conn.SetReadDeadline(time.Now().Add(1 * time.Minute)); err != nil {
conn.Close()
listener.sendError(&acceptError{error: err, temporary: true})
return
}
header, err := ReadHeader(conn)
if err != nil {
conn.Close()
err = fmt.Errorf("reading proxy header: %w", err)
listener.sendError(&acceptError{error: err, temporary: true})
return
}
if err := conn.SetReadDeadline(time.Time{}); err != nil {
conn.Close()
listener.sendError(&acceptError{error: err, temporary: true})
return
}
proxyConn := &proxyConn{
Conn: conn,
localAddr: header.LocalAddr,
remoteAddr: header.RemoteAddr,
}
if !listener.sendConn(proxyConn) {
proxyConn.Close()
}
}
func (listener *proxyListener) sendError(err error) bool {
select {
case listener.errors <- err:
return true
case <-listener.done:
return false
}
}
func (listener *proxyListener) sendConn(conn net.Conn) bool {
select {
case listener.conns <- conn:
return true
case <-listener.done:
return false
}
}
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