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proxy.go
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proxy.go
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package main
import (
"bytes"
"github.com/Sirupsen/logrus"
"io"
"net"
"strconv"
"sync"
)
const (
NETBUF_SIZE = 2048 // bytes
)
var (
poolNetBuffers sync.Pool
)
// var-constants
var (
HEAD_CONNECTION = []byte("CONNECTION")
HEAD_CONNECTION_KEEP_ALIVE = []byte("KEEP-ALIVE")
HEAD_CONTENT_LENGTH = []byte("CONTENT-LENGTH")
)
// Get or create network buffer for proxy
func netbufGet() (buf []byte) {
bufInterface := poolNetBuffers.Get()
if bufInterface == nil {
buf = make([]byte, NETBUF_SIZE)
} else {
buf = bufInterface.([]byte)
// prevent data leak
for i := range buf {
buf[i] = 0
}
}
return buf
}
func netbufPut(buf []byte) {
poolNetBuffers.Put(buf)
}
func proxyHTTPHeaders(targetConn net.Conn, sourceConn net.Conn) (keepalive bool, contentLength int64) {
buf := netbufGet()
defer netbufPut(buf)
var totalReadBytes int
// Read lines
readHeaderLines:
for {
var i int
var headerStart []byte
for i = 0; i < len(buf); i++ {
readBytes, err := sourceConn.Read(buf[i : i+1])
totalReadBytes += readBytes
if err != nil {
logrus.Debugf("Error while read header from '%v': %v", sourceConn.RemoteAddr(), err)
targetConn.Close()
sourceConn.Close()
return
}
if readBytes != 1 {
logrus.Infof("Can't read a byte from header from '%v'", sourceConn.RemoteAddr())
targetConn.Close()
sourceConn.Close()
return
}
if buf[i] == ':' || buf[i] == '\n' {
headerStart = buf[:i+1]
logrus.Debugf("Header Name '%v' -> '%v': '%s'", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), buf[:i])
break
}
}
if len(headerStart) == 0 {
logrus.Infof("Header line longer then buffer (%v bytes). Force close connection. '%v' -> '%v'.", len(buf), sourceConn.RemoteAddr(), targetConn.RemoteAddr())
targetConn.Close()
sourceConn.Close()
return
}
// Empty line - end http headers
if bytes.Equal(headerStart, []byte("\n")) || bytes.Equal(headerStart, []byte("\r\n")) {
break readHeaderLines
}
headerName := bytes.ToUpper(headerStart[:len(headerStart)-1]) // Cut trailing colon from start
skipHeader := false
for _, ownHeader := range cutHeaders {
if bytes.Equal(ownHeader, headerName) {
skipHeader = true
break
}
ownHeaderS := string(ownHeader)
headerNameS := string(headerName)
skipHeader = ownHeaderS == headerNameS
}
if skipHeader {
logrus.Debugf("Skip header: '%v' -> '%v': '%s'", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), headerName)
buf[0] = headerStart[len(headerStart)-1]
for buf[0] != '\n' {
_, err := sourceConn.Read(buf[:1])
if err != nil {
logrus.Infof("Error read header. Close connections. '%v' -> '%v': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), err)
sourceConn.Close()
targetConn.Close()
return
}
}
continue readHeaderLines
}
logrus.Debugf("Copy header: '%v' -> '%v': '%s'", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), headerName)
// copy header without changes
_, err := targetConn.Write(headerStart)
if err != nil {
logrus.Infof("Write header start, from '%v' to '%v', headerStart='%s': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), headerStart, err)
sourceConn.Close()
targetConn.Close()
return
}
needHeaderContent := bytes.Equal(headerName, HEAD_CONTENT_LENGTH) || bytes.Equal(headerName, HEAD_CONNECTION)
headerContent := bytes.NewBuffer(buf[1:])
headerContent.Reset()
for buf[0] != '\n' {
readBytes, err := sourceConn.Read(buf[:1])
if err != nil {
logrus.Infof("Error read header to copy. Close connections. '%v' -> '%v': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), err)
sourceConn.Close()
targetConn.Close()
return
}
if readBytes != 1 {
logrus.Infof("Header copy read bytes != 1. Error. Close connections. '%v' -> '%v'", sourceConn.RemoteAddr(), targetConn.RemoteAddr())
sourceConn.Close()
targetConn.Close()
return
}
_, err = targetConn.Write(buf[:1])
if err != nil {
logrus.Infof("Error write header. Close connections. '%v' -> '%v': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), err)
sourceConn.Close()
targetConn.Close()
return
}
if needHeaderContent {
headerContent.WriteByte(buf[0])
}
}
if needHeaderContent {
switch {
case bytes.Equal(headerName, HEAD_CONNECTION):
keepalive = bytes.EqualFold(HEAD_CONNECTION_KEEP_ALIVE, bytes.TrimSpace(headerContent.Bytes()))
case bytes.Equal(headerName, HEAD_CONTENT_LENGTH):
contentLength, err = strconv.ParseInt(string(bytes.TrimSpace(headerContent.Bytes())), 10, 64)
if err == nil {
logrus.Debugf("Header content-length parsed from '%v' to '%v': %v", sourceConn.RemoteAddr(),
targetConn.RemoteAddr(), contentLength)
} else {
logrus.Infof("Can't header content-length parsed from '%v' to '%v' content '%s': %v", sourceConn.RemoteAddr(),
targetConn.RemoteAddr(), headerContent.Bytes(), err)
contentLength = 0
}
default:
logrus.Debug("ERROR. Unknow why i need header content. Code error.")
}
}
}
remoteTcpAddr := sourceConn.RemoteAddr().(*net.TCPAddr)
remoteAddrString := remoteTcpAddr.IP.String()
headerBuf := bytes.NewBuffer(buf)
headerBuf.Reset()
// Write real IP
for _, header := range realIPHeaderNames {
headerBuf.Write(header)
headerBuf.WriteByte(':')
headerBuf.WriteString(remoteAddrString)
headerBuf.Write([]byte("\r\n"))
}
headerBuf.Write(additionalHeaders)
headerBuf.Write([]byte("\r\n")) // end http headers
logrus.Debugf("Add headers. '%v' -> '%v': '%s'", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), headerBuf.Bytes())
_, err := targetConn.Write(headerBuf.Bytes())
if err != nil {
logrus.Infof("Error while write real ip headers to target '%v' -> '%v': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), err)
}
return
}
func startProxy(targetAddr net.TCPAddr, in net.Conn) {
targetConnCommon, err := net.DialTimeout("tcp", targetAddr.String(), *targetConnTimeout)
if err != nil {
logrus.Warnf("Can't connect to target '%v': %v", targetAddr.String(), err)
return
}
targetConn, ok := targetConnCommon.(*net.TCPConn)
if !ok {
logrus.Errorf("Can't cast connection to tcp connection, target '%v'", targetAddr.String())
return
}
switch *proxyMode {
case "http":
startProxyHTTP(targetConn, in)
case "tcp":
startProxyTCP(targetConn, in)
default:
logrus.Panicf("Unknow proxy mode: %v", *proxyMode)
}
}
func startProxyHTTP(targetConn net.Conn, sourceConn net.Conn) {
logrus.Infof("Start http-proxy connection from '%v' to'%v'", sourceConn.RemoteAddr(), targetConn.RemoteAddr())
// answer from server proxy without changes
go func() {
buf := netbufGet()
defer netbufPut(buf)
_, err := io.CopyBuffer(sourceConn, targetConn, buf)
logrus.Debugf("Connection closed with error1 '%v' -> '%v': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), err)
sourceConn.Close()
targetConn.Close()
}()
// proxy incoming traffic, parse every headers
go func() {
buf := netbufGet()
defer netbufPut(buf)
var summBytesCopied int64
for {
keepalive, contentLength := proxyHTTPHeaders(targetConn, sourceConn)
if keepalive {
logrus.Debugf("Start keep-alieved proxy. '%v' -> '%v', content-length '%v'", sourceConn.RemoteAddr(),
targetConn.RemoteAddr(), contentLength)
bytesCopied, err := io.CopyBuffer(targetConn, io.LimitReader(sourceConn, contentLength), buf)
summBytesCopied += bytesCopied
logrus.Debugf("Connection chunk copied '%v' -> '%v', bytes transferred '%v' (%v), error: %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), bytesCopied, summBytesCopied, err)
if err != nil {
logrus.Debugf("Connection closed '%v' -> '%v', bytes transferred '%v' (%v), error: %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), bytesCopied, summBytesCopied, err)
}
} else {
logrus.Debugf("Start proxy without support keepalive middle headers '%v' -> '%v'", sourceConn.RemoteAddr(), targetConn.RemoteAddr())
bytesCopied, err := io.CopyBuffer(targetConn, sourceConn, buf)
summBytesCopied += bytesCopied
logrus.Debugf("Connection closed '%v' -> '%v', bytes transferred '%v' (%v), error: %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), bytesCopied, summBytesCopied, err)
sourceConn.Close()
targetConn.Close()
return
}
}
}()
}
func startProxyTCP(targetConn net.Conn, sourceConn net.Conn) {
logrus.Infof("Start tcp-proxy connection from '%v' to'%v'", sourceConn.RemoteAddr(), targetConn.RemoteAddr())
go func() {
buf := netbufGet()
defer netbufPut(buf)
_, err := io.CopyBuffer(targetConn, sourceConn, buf)
logrus.Debugf("Connection closed with error2 '%v' -> '%v': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), err)
sourceConn.Close()
targetConn.Close()
}()
go func() {
buf := netbufGet()
defer netbufPut(buf)
_, err := io.CopyBuffer(sourceConn, targetConn, buf)
logrus.Debugf("Connection closed with error3 '%v' -> '%v': %v", sourceConn.RemoteAddr(), targetConn.RemoteAddr(), err)
sourceConn.Close()
targetConn.Close()
}()
}