first commit

go.mod

@@ -0,0 +1,11 @@
+module tcp-proxy
+
+go 1.19
+
+require (
+	github.com/integrii/flaggy v1.5.2 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.17 // indirect
+	github.com/rs/zerolog v1.29.0 // indirect
+	golang.org/x/sys v0.4.0 // indirect
+)

go.sum

@@ -0,0 +1,22 @@
+github.com/coreos/go-systemd/v22 v22.3.3-0.20220203105225-a9a7ef127534/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/integrii/flaggy v1.5.2 h1:bWV20MQEngo4hWhno3i5Z9ISPxLPKj9NOGNwTWb/8IQ=
+github.com/integrii/flaggy v1.5.2/go.mod h1:dO13u7SYuhk910nayCJ+s1DeAAGC1THCMj1uSFmwtQ8=
+github.com/mattn/go-colorable v0.1.12/go.mod h1:u5H1YNBxpqRaxsYJYSkiCWKzEfiAb1Gb520KVy5xxl4=
+github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
+github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-isatty v0.0.14/go.mod h1:7GGIvUiUoEMVVmxf/4nioHXj79iQHKdU27kJ6hsGG94=
+github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-isatty v0.0.17 h1:BTarxUcIeDqL27Mc+vyvdWYSL28zpIhv3RoTdsLMPng=
+github.com/mattn/go-isatty v0.0.17/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/rs/xid v1.4.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
+github.com/rs/zerolog v1.29.0 h1:Zes4hju04hjbvkVkOhdl2HpZa+0PmVwigmo8XoORE5w=
+github.com/rs/zerolog v1.29.0/go.mod h1:NILgTygv/Uej1ra5XxGf82ZFSLk58MFGAUS2o6usyD0=
+golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.4.0 h1:Zr2JFtRQNX3BCZ8YtxRE9hNJYC8J6I1MVbMg6owUp18=
+golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

main.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"io"
+	"net"
+	"os"
+	"sync"
+
+	"github.com/integrii/flaggy"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+func main() {
+	log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
+
+	var (
+		listenAddr  = ":8000"
+		forwardAddr string
+	)
+
+	flaggy.String(&listenAddr, "l", "listen", "Address to listen on")
+	flaggy.String(&forwardAddr, "f", "forward", "Address to forward to")
+	flaggy.Parse()
+
+	if forwardAddr == "" {
+		log.Fatal().Msg("Forward address is required")
+	}
+
+	ln, err := net.Listen("tcp", listenAddr)
+	if err != nil {
+		log.Panic().Err(err).Msg("Failed to listen")
+	}
+	defer ln.Close()
+
+	log.Info().Str("Listen Address", listenAddr).Msg("Listening")
+
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			log.Err(err).Msg("Failed to accept connection")
+			continue
+		}
+		log.Info().Str("Incoming Address", conn.RemoteAddr().String()).Msg("Connection accepted")
+
+		go handleConnection(conn, forwardAddr)
+	}
+
+}
+
+func handleConnection(conn net.Conn, forwardAddr string) {
+	defer conn.Close()
+
+	fwrd, err := net.Dial("tcp", forwardAddr)
+	if err != nil {
+		log.Err(err).Msg("Failed to connect to forward address")
+		return
+	}
+
+	var wg sync.WaitGroup
+
+	wg.Add(2)
+
+	go func() {
+		defer fwrd.Close()
+		defer wg.Done()
+
+		_, err := io.Copy(fwrd, conn)
+		if err != nil {
+			log.Err(err).Msg("Failed to copy from connection to forward address")
+		}
+	}()
+
+	go func() {
+		defer conn.Close()
+		defer wg.Done()
+
+		_, err := io.Copy(conn, fwrd)
+		if err != nil {
+			log.Err(err).Msg("Failed to copy from forward address to connection")
+		}
+	}()
+
+	wg.Wait()
+	log.Info().Str("Incoming Address", conn.RemoteAddr().String()).Msg("Connection closed")
+}