Add proxy protocol support

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
     name: Test
     strategy:
       matrix:
-        go-version: [1.13.x, 1.14.x]
+        go-version: [1.20.x]
         platform: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:

cmd/tcp-proxy/main.go

@@ -17,16 +17,18 @@ var (
 	connid  = uint64(0)
 	logger  proxy.ColorLogger
 
-	localAddr   = flag.String("l", ":9999", "local address")
-	remoteAddr  = flag.String("r", "localhost:80", "remote address")
-	verbose     = flag.Bool("v", false, "display server actions")
-	veryverbose = flag.Bool("vv", false, "display server actions and all tcp data")
-	nagles      = flag.Bool("n", false, "disable nagles algorithm")
-	hex         = flag.Bool("h", false, "output hex")
-	colors      = flag.Bool("c", false, "output ansi colors")
-	unwrapTLS   = flag.Bool("unwrap-tls", false, "remote connection with TLS exposed unencrypted locally")
-	match       = flag.String("match", "", "match regex (in the form 'regex')")
-	replace     = flag.String("replace", "", "replace regex (in the form 'regex~replacer')")
+	localAddr            = flag.String("l", ":9999", "local address")
+	remoteAddr           = flag.String("r", "localhost:80", "remote address")
+	verbose              = flag.Bool("v", false, "display server actions")
+	veryverbose          = flag.Bool("vv", false, "display server actions and all tcp data")
+	nagles               = flag.Bool("n", false, "disable nagles algorithm")
+	hex                  = flag.Bool("h", false, "output hex")
+	colors               = flag.Bool("c", false, "output ansi colors")
+	unwrapTLS            = flag.Bool("unwrap-tls", false, "remote connection with TLS exposed unencrypted locally")
+	match                = flag.String("match", "", "match regex (in the form 'regex')")
+	replace              = flag.String("replace", "", "replace regex (in the form 'regex~replacer')")
+	proxyProtocol        = flag.Bool("p", false, "Enable proxy protocol for passthrought the real IP")
+	proxyProtocolVersion = flag.Int("pv", 2, "Proxy protocol version (1, 2) default: 2")
 )
 
 func main() {
@@ -90,6 +92,11 @@ func main() {
 			Color:       *colors,
 		}
 
+		p.ProxyProtocol = proxy.ProxyProtocol{
+			Enabled: *proxyProtocol,
+			Version: byte(*proxyProtocolVersion),
+		}
+
 		go p.Start()
 	}
 }

go.mod

@@ -5,4 +5,5 @@ go 1.13
 require (
 	github.com/mattn/go-colorable v0.1.4 // indirect
 	github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b
+	github.com/pires/go-proxyproto v0.7.0 // indirect
 )

go.sum

@@ -4,5 +4,7 @@ github.com/mattn/go-isatty v0.0.8 h1:HLtExJ+uU2HOZ+wI0Tt5DtUDrx8yhUqDcp7fYERX4CE
 github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
 github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b h1:j7+1HpAFS1zy5+Q4qx1fWh90gTKwiN4QCGoY9TWyyO4=
 github.com/mgutz/ansi v0.0.0-20170206155736-9520e82c474b/go.mod h1:01TrycV0kFyexm33Z7vhZRXopbI8J3TDReVlkTgMUxE=
+github.com/pires/go-proxyproto v0.7.0 h1:IukmRewDQFWC7kfnb66CSomk2q/seBuilHBYFwyq0Hs=
+github.com/pires/go-proxyproto v0.7.0/go.mod h1:Vz/1JPY/OACxWGQNIRY2BeyDmpoaWmEP40O9LbuiFR4=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223 h1:DH4skfRX4EBpamg7iV4ZlCpblAHI6s6TDM39bFZumv8=
 golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=

proxy.go

@@ -4,14 +4,16 @@ import (
 	"crypto/tls"
 	"io"
 	"net"
+
+	proxyproto "github.com/pires/go-proxyproto"
 )
 
 // Proxy - Manages a Proxy connection, piping data between local and remote.
 type Proxy struct {
 	sentBytes     uint64
 	receivedBytes uint64
 	laddr, raddr  *net.TCPAddr
-	lconn, rconn  io.ReadWriteCloser
+	lconn, rconn  net.Conn
 	erred         bool
 	errsig        chan bool
 	tlsUnwrapp    bool
@@ -21,9 +23,15 @@ type Proxy struct {
 	Replacer func([]byte) []byte
 
 	// Settings
-	Nagles    bool
-	Log       Logger
-	OutputHex bool
+	Nagles        bool
+	Log           Logger
+	OutputHex     bool
+	ProxyProtocol ProxyProtocol
+}
+
+type ProxyProtocol struct {
+	Version byte
+	Enabled bool
 }
 
 // New - Create a new Proxy instance. Takes over local connection passed in,
@@ -64,6 +72,7 @@ func (p *Proxy) Start() {
 	} else {
 		p.rconn, err = net.DialTCP("tcp", nil, p.raddr)
 	}
+
 	if err != nil {
 		p.Log.Warn("Remote connection failed: %s", err)
 		return
@@ -83,6 +92,18 @@ func (p *Proxy) Start() {
 	//display both ends
 	p.Log.Info("Opened %s >>> %s", p.laddr.String(), p.raddr.String())
 
+	if p.ProxyProtocol.Enabled {
+		header := &proxyproto.Header{
+			Version:           p.ProxyProtocol.Version,
+			Command:           proxyproto.PROXY,
+			TransportProtocol: proxyproto.TCPv4,
+			SourceAddr:        p.lconn.RemoteAddr(),
+			DestinationAddr:   p.rconn.RemoteAddr(),
+		}
+		p.Log.Info("Send proxy header from (%s to %s)", header.SourceAddr.String(), header.DestinationAddr.String())
+		header.WriteTo(p.rconn)
+	}
+
 	//bidirectional copy
 	go p.pipe(p.lconn, p.rconn)
 	go p.pipe(p.rconn, p.lconn)