Output frame information [Close #2]

proxy/go.mod

@@ -1,3 +1,5 @@
 module proxy
 
 go 1.13
+
+require github.com/mdlayher/ethernet v0.0.0-20190606142754-0394541c37b7 // indirect

proxy/go.sum

@@ -0,0 +1,12 @@
+github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
+github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
+github.com/mdlayher/ethernet v0.0.0-20190606142754-0394541c37b7 h1:lez6TS6aAau+8wXUP3G9I3TGlmPFEq2CTxBaRqY6AGE=
+github.com/mdlayher/ethernet v0.0.0-20190606142754-0394541c37b7/go.mod h1:U6ZQobyTjI/tJyq2HG+i/dfSoFUt8/aZCM+GKtmFk/Y=
+github.com/mdlayher/raw v0.0.0-20190606142536-fef19f00fc18/go.mod h1:7EpbotpCmVZcu+KCX4g9WaRNuu11uyhiW7+Le1dKawg=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190419010253-1f3472d942ba/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190603091049-60506f45cf65/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190418153312-f0ce4c0180be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190606122018-79a91cf218c4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

proxy/main.go

@@ -1,11 +1,13 @@
 package main
 
 import (
+	"encoding/binary"
 	"fmt"
+	"github.com/mdlayher/ethernet"
 	"io"
+	"log"
 	"os"
 	"proxy/cmd"
-	"unicode"
 )
 
 // Start the two plugs and run two concurrent forward methods
@@ -22,27 +24,43 @@ func main() {
 
 // Reads from an input and writes to and output,
 // do things to the content in between.
-// For now only output it in xxd format.
+// For now only output the frames information
 // Is meant to be run concurrently with "go pipeForward(...)"
 func pipeForward(reader io.Reader, writer io.Writer, prefix string) {
-	i := 0
 	for {
-		bytes := make([]byte, 16)
-		bytesReadable := make([]byte, 16)
-		_, err := reader.Read(bytes)
+		// Read frame length and print it
+		frameLength := make([]byte, 2)
+		_, err := reader.Read(frameLength)
 		if err == io.EOF {
 			break
 		}
-		for i, ch := range bytes {
-			if ch > unicode.MaxASCII || ch < '\u0020' {
-				bytesReadable[i] = '\u002E'
-			} else {
-				bytesReadable[i] = ch
-			}
+		frameLengthInt := int(binary.BigEndian.Uint16(frameLength))
+		os.Stdout.WriteString(fmt.Sprintf("%s Frame length: %d\n", prefix, frameLengthInt))
+
+		// Read actual frame
+		frameBytes := make([]byte, frameLengthInt)
+		_, err = reader.Read(frameBytes)
+		if err == io.EOF {
+			break
 		}
-		xxdString := fmt.Sprintf("%s%08x: %04x %04x %04x %04x %04x %04x %04x %04x  %s\n", prefix, i, bytes[0:1], bytes[2:3], bytes[4:5], bytes[6:7], bytes[8:9], bytes[10:11], bytes[12:13], bytes[14:15], bytesReadable)
-		os.Stdout.WriteString(xxdString)
-		writer.Write(bytes)
-		i += 16
+
+		// Marshal frame from binary
+		var frame ethernet.Frame
+		if e := (&frame).UnmarshalBinary(frameBytes); e != nil {
+			log.Printf("failed to unmarshal frame: %#v\n", e)
+		}
+
+		// Print frame information
+		fmt.Printf(
+			"src: %s\ndst: %s\ntyp: %s\npayload\n%x\n",
+			frame.Source,
+			frame.Destination,
+			frame.EtherType,
+			frame.Payload,
+			)
+
+		// Forward original frame to other plug
+		writer.Write(frameLength)
+		writer.Write(frameBytes)
 	}
 }