wip

go.mod

@@ -1,3 +1,9 @@
 module aim-oscar
 
 go 1.16
+
+require (
+	github.com/ghostiam/binstruct v1.0.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/xhebox/bstruct v0.0.0-20210125172452-c36e1006cf29 // indirect
+)

go.sum

@@ -0,0 +1,13 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/ghostiam/binstruct v1.0.1 h1:sg7Hi5c5b0noCDfRQpx3K2x9HLJYRafKnQRif7Orkek=
+github.com/ghostiam/binstruct v1.0.1/go.mod h1:+NZwEDbcfME8MhF7nQRjAZV4U00c6XpNuk+nkvOxzvo=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/xhebox/bstruct v0.0.0-20210125172452-c36e1006cf29 h1:lMx3E/urZ0wDiG27VXTEEq0RG/MHsscHPkYiS5KIjcE=
+github.com/xhebox/bstruct v0.0.0-20210125172452-c36e1006cf29/go.mod h1:KZ+p86hKYsjjg3oG2RfDFJFGkn85Z60Xhc5E5P58FXY=

main.go

@@ -9,6 +9,8 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+
+	"github.com/ghostiam/binstruct"
 )
 
 const (
@@ -47,7 +49,7 @@ func main() {
 			os.Exit(1)
 		}
 
-		ctx := context.WithValue(context.Background(), "session", NewSession(conn))
+		ctx := NewContextWithSession(context.Background(), conn)
 		log.Printf("Connection from %v", conn.RemoteAddr())
 
 		go handleTCPConnection(ctx, conn)
@@ -65,7 +67,8 @@ func handleTCPConnection(ctx context.Context, conn net.Conn) {
 
 	buf := make([]byte, 1024)
 	for {
-		session := ctx.Value("session").(*Session)
+		session, err := CurrentSession(ctx)
+		panicIfError(err)
 		if !session.GreetedClient {
 			// send a hello
 			hello := NewFLAP(ctx, 1, []byte{0, 0, 0, 1})
@@ -85,17 +88,18 @@ func handleTCPConnection(ctx context.Context, conn net.Conn) {
 		}
 
 		fmt.Printf("%v ->\n%s\n\n", conn.RemoteAddr(), prettyBytes(buf[:n]))
-		handleMessage(ctx, buf[:n])
-	}
-}
 
-func handleMessage(ctx context.Context, buf []byte) {
 		flap := &FLAP{}
-	flap.UnmarshalBinary(buf)
+		binstruct.UnmarshalBE(buf[:n], flap)
 
-	if flap.Header.Channel == 1 {
+		handleMessage(ctx, flap)
+	}
+}
 
-	} else if flap.Header.Channel == 2 {
+func handleMessage(ctx context.Context, flap *FLAP) {
+	if flap.Channel == 1 {
+
+	} else if flap.Channel == 2 {
 		snac := &SNAC{}
 		err := snac.UnmarshalBinary(flap.Data)
 		panicIfError(err)

session.go

@@ -1,11 +1,22 @@
 package main
 
 import (
+	"context"
 	"encoding"
 	"fmt"
 	"net"
 )
 
+type sessionKey string
+
+func (s sessionKey) String() string {
+	return "oscar-" + string(s)
+}
+
+var (
+	currentSession = sessionKey("session")
+)
+
 type Session struct {
 	Conn           net.Conn
 	SequenceNumber uint16
@@ -20,6 +31,19 @@ func NewSession(conn net.Conn) *Session {
 	}
 }
 
+func NewContextWithSession(ctx context.Context, conn net.Conn) context.Context {
+	session := NewSession(conn)
+	return context.WithValue(ctx, currentSession, session)
+}
+
+func CurrentSession(ctx context.Context) (session *Session, err error) {
+	session, ok := ctx.Value(currentSession).(*Session)
+	if !ok {
+		return nil, fmt.Errorf("no session in context")
+	}
+	return
+}
+
 func (s *Session) Send(m encoding.BinaryMarshaler) error {
 	bytes, err := m.MarshalBinary()
 	if err != nil {

util.go

@@ -1,11 +1,7 @@
 package main
 
 import (
-	"bytes"
-	"encoding/binary"
 	"encoding/hex"
-	"fmt"
-	"io"
 )
 
 func prettyBytes(bytes []byte) string {
@@ -22,28 +18,8 @@ func prettyBytes(bytes []byte) string {
 	return res
 }
 
-func printBytes(bytes []byte) {
-	fmt.Printf("%s\n", prettyBytes(bytes))
-}
-
 func panicIfError(err error) {
 	if err != nil {
 		panic(err)
 	}
 }
-
-func readNBytes(buf *bytes.Buffer, n int) ([]byte, error) {
-	res := make([]byte, n)
-	_, err := io.ReadFull(buf, res)
-	return res, err
-}
-
-func mustReadNBytes(buf *bytes.Buffer, n int) []byte {
-	res, err := readNBytes(buf, n)
-	panicIfError(err)
-	return res
-}
-
-func mustRead(buf *bytes.Buffer, dest interface{}) {
-	panicIfError(binary.Read(buf, binary.BigEndian, dest))
-}