fix incorrect type of Capsule-Protocol header (#55)

The required value is ?1. According to the structured HTTP field
specification (RFC 8941, section 3.3.6) this is a bool, and not an
integer.

proxy.go

@@ -2,7 +2,6 @@ package masque
 
 import (
 	"context"
-	"fmt"
 	"io"
 	"log"
 	"net"
@@ -13,30 +12,13 @@ import (
 	"github.com/quic-go/quic-go"
 	"github.com/quic-go/quic-go/http3"
 	"github.com/quic-go/quic-go/quicvarint"
-
-	"github.com/dunglas/httpsfv"
-)
-
-const (
-	requestProtocol = "connect-udp"
-	capsuleHeader   = "Capsule-Protocol"
 )
 
 const (
 	uriTemplateTargetHost = "target_host"
 	uriTemplateTargetPort = "target_port"
 )
 
-var capsuleProtocolHeaderValue string
-
-func init() {
-	v, err := httpsfv.Marshal(httpsfv.NewItem(1))
-	if err != nil {
-		panic(fmt.Sprintf("failed to marshal capsule protocol header value: %v", err))
-	}
-	capsuleProtocolHeaderValue = v
-}
-
 type proxyEntry struct {
 	str  http3.Stream
 	conn *net.UDPConn

proxy_test.go

@@ -30,7 +30,7 @@ func newRequest(target string) *http.Request {
 	req := httptest.NewRequest(http.MethodGet, target, nil)
 	req.Method = http.MethodConnect
 	req.Proto = requestProtocol
-	req.Header.Add("Capsule-Protocol", "1")
+	req.Header.Add("Capsule-Protocol", capsuleProtocolHeaderValue)
 	return req
 }
 

request.go

@@ -4,12 +4,28 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"reflect"
 	"strconv"
 
 	"github.com/dunglas/httpsfv"
 	"github.com/yosida95/uritemplate/v3"
 )
 
+const (
+	requestProtocol = "connect-udp"
+	capsuleHeader   = "Capsule-Protocol"
+)
+
+var capsuleProtocolHeaderValue string
+
+func init() {
+	v, err := httpsfv.Marshal(httpsfv.NewItem(true))
+	if err != nil {
+		panic(fmt.Sprintf("failed to marshal capsule protocol header value: %v", err))
+	}
+	capsuleProtocolHeaderValue = v
+}
+
 // Request is the parsed CONNECT-UDP request returned from ParseRequest.
 // Target is the target server that the client requests to connect to.
 // It can either be DNS name:port or an IP:port.
@@ -57,10 +73,15 @@ func ParseRequest(r *http.Request, template *uritemplate.Template) (*Request, er
 			Err:        fmt.Errorf("invalid capsule header value: %s", capsuleHeaderValues),
 		}
 	}
-	if v, ok := item.Value.(int64); !ok || v != 1 {
+	if v, ok := item.Value.(bool); !ok {
+		return nil, &RequestParseError{
+			HTTPStatus: http.StatusBadRequest,
+			Err:        fmt.Errorf("incorrect capsule header value type: %s", reflect.TypeOf(item.Value)),
+		}
+	} else if !v {
 		return nil, &RequestParseError{
 			HTTPStatus: http.StatusBadRequest,
-			Err:        fmt.Errorf("incorrect capsule header value: %d", v),
+			Err:        fmt.Errorf("incorrect capsule header value: %t", item.Value),
 		}
 	}
 

request_test.go

@@ -4,13 +4,21 @@ import (
 	"net/http"
 	"testing"
 
+	"github.com/dunglas/httpsfv"
 	"github.com/stretchr/testify/require"
 	"github.com/yosida95/uritemplate/v3"
 )
 
 func TestRequestParsing(t *testing.T) {
 	template := uritemplate.MustNew("https://localhost:1234/masque?h={target_host}&p={target_port}")
 
+	t.Run("invalid target port", func(t *testing.T) {
+		req := newRequest("https://localhost:1234/masque?h=localhost&p=1337")
+		r, err := ParseRequest(req, template)
+		require.NoError(t, err)
+		require.Equal(t, r.Target, "localhost:1337")
+	})
+
 	t.Run("wrong request method", func(t *testing.T) {
 		req := newRequest("https://localhost:1234/masque")
 		req.Method = http.MethodHead
@@ -43,11 +51,21 @@ func TestRequestParsing(t *testing.T) {
 		require.Equal(t, http.StatusBadRequest, err.(*RequestParseError).HTTPStatus)
 	})
 
-	t.Run("invalid Capsule-Protocol header value", func(t *testing.T) {
+	t.Run("invalid Capsule-Protocol header value type", func(t *testing.T) {
 		req := newRequest("https://localhost:1234/masque")
-		req.Header.Set("Capsule-Protocol", "2")
+		req.Header.Set("Capsule-Protocol", "1")
 		_, err := ParseRequest(req, template)
-		require.EqualError(t, err, "incorrect capsule header value: 2")
+		require.EqualError(t, err, "incorrect capsule header value type: int64")
+		require.Equal(t, http.StatusBadRequest, err.(*RequestParseError).HTTPStatus)
+	})
+
+	t.Run("invalid Capsule-Protocol header value", func(t *testing.T) {
+		req := newRequest("https://localhost:1234/masque")
+		v, err := httpsfv.Marshal(httpsfv.NewItem(false))
+		require.NoError(t, err)
+		req.Header.Set("Capsule-Protocol", v)
+		_, err = ParseRequest(req, template)
+		require.EqualError(t, err, "incorrect capsule header value: false")
 		require.Equal(t, http.StatusBadRequest, err.(*RequestParseError).HTTPStatus)
 	})