TUN-8592: Use metadata from the edge to determine if request body is empty for QUIC transport

If the metadata is missing, fallback to decide based on protocol, http
method, transferring and content length

connection/quic.go

@@ -42,12 +42,26 @@ const (
 	HTTPMethodKey = "HttpMethod"
 	// HTTPHostKey is used to get or set http Method in QUIC ALPN if the underlying proxy connection type is HTTP.
 	HTTPHostKey = "HttpHost"
+	// HTTPRequestBodyHintKey is used in ConnectRequest metadata to indicate if the request has body
+	HTTPRequestBodyHintKey = "HttpReqBodyHint"
 
 	QUICMetadataFlowID = "FlowID"
 	// emperically this capacity has been working well
 	demuxChanCapacity = 16
 )
 
+type RequestBodyHint uint64
+
+const (
+	RequestBodyHintMissing RequestBodyHint = iota
+	RequestBodyHintEmpty
+	RequestBodyHintHasData
+)
+
+func (rbh RequestBodyHint) String() string {
+	return [...]string{"missing", "empty", "data"}[rbh]
+}
+
 var (
 	portForConnIndex = make(map[uint8]int, 0)
 	portMapMutex     sync.Mutex
@@ -486,7 +500,6 @@ func buildHTTPRequest(
 	dest := connectRequest.Dest
 	method := metadata[HTTPMethodKey]
 	host := metadata[HTTPHostKey]
-	isWebsocket := connectRequest.Type == pogs.ConnectionTypeWebsocket
 
 	req, err := http.NewRequestWithContext(ctx, method, dest, body)
 	if err != nil {
@@ -511,13 +524,8 @@ func buildHTTPRequest(
 		return nil, fmt.Errorf("Error setting content-length: %w", err)
 	}
 
-	// Go's client defaults to chunked encoding after a 200ms delay if the following cases are true:
+	if shouldSetRequestBodyToEmpty(connectRequest, metadata, req) {
-	//   * the request body blocks
+		log.Debug().Str("host", req.Host).Str("method", req.Method).Msg("Set request to have no body")
-	//   * the content length is not set (or set to -1)
-	//   * the method doesn't usually have a body (GET, HEAD, DELETE, ...)
-	//   * there is no transfer-encoding=chunked already set.
-	// So, if transfer cannot be chunked and content length is 0, we dont set a request body.
-	if !isWebsocket && !isTransferEncodingChunked(req) && req.ContentLength == 0 {
 		req.Body = http.NoBody
 	}
 	stripWebsocketUpgradeHeader(req)
@@ -542,6 +550,35 @@ func isTransferEncodingChunked(req *http.Request) bool {
 	return strings.Contains(strings.ToLower(transferEncodingVal), "chunked")
 }
 
+// Borrowed from https://github.com/golang/go/blob/go1.22.6/src/net/http/request.go#L1541
+func requestMethodUsuallyLacksBody(req *http.Request) bool {
+	switch strings.ToUpper(req.Method) {
+	case "GET", "HEAD", "DELETE", "OPTIONS", "PROPFIND", "SEARCH":
+		return true
+	}
+	return false
+}
+
+func shouldSetRequestBodyToEmpty(connectRequest *pogs.ConnectRequest, metadata map[string]string, req *http.Request) bool {
+	switch metadata[HTTPRequestBodyHintKey] {
+	case RequestBodyHintEmpty.String():
+		return true
+	case RequestBodyHintHasData.String():
+		return false
+	default:
+	}
+
+	isWebsocket := connectRequest.Type == pogs.ConnectionTypeWebsocket
+	// Go's client defaults to chunked encoding after a 200ms delay if the following cases are true:
+	//   * the request body blocks
+	//   * the content length is not set (or set to -1)
+	//   * the method doesn't usually have a body (GET, HEAD, DELETE, ...)
+	//   * there is no transfer-encoding=chunked already set.
+	// So, if transfer cannot be chunked and content length is 0, we dont set a request body.
+	// Reference: https://github.com/golang/go/blob/go1.22.2/src/net/http/transfer.go#L192-L206
+	return !isWebsocket && requestMethodUsuallyLacksBody(req) && !isTransferEncodingChunked(req) && req.ContentLength == 0
+}
+
 // A helper struct that guarantees a call to close only affects read side, but not write side.
 type nopCloserReadWriter struct {
 	io.ReadWriteCloser

connection/quic_test.go

@@ -484,6 +484,125 @@ func TestBuildHTTPRequest(t *testing.T) {
 			},
 			body: io.NopCloser(&bytes.Buffer{}),
 		},
+		{
+			name: "if edge sends the body is empty hint, set body to empty",
+			connectRequest: &pogs.ConnectRequest{
+				Dest: "http://test.com",
+				Metadata: []pogs.Metadata{
+					{
+						Key: "HttpHeader:Another-Header",
+						Val: "Misc",
+					},
+					{
+						Key: "HttpHost",
+						Val: "cf.host",
+					},
+					{
+						Key: "HttpMethod",
+						Val: "put",
+					},
+					{
+						Key: HTTPRequestBodyHintKey,
+						Val: RequestBodyHintEmpty.String(),
+					},
+				},
+			},
+			req: &http.Request{
+				Method: "put",
+				URL: &url.URL{
+					Scheme: "http",
+					Host:   "test.com",
+				},
+				Proto:      "HTTP/1.1",
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+				Header: http.Header{
+					"Another-Header": []string{"Misc"},
+				},
+				ContentLength: 0,
+				Host:          "cf.host",
+				Body:          http.NoBody,
+			},
+			body: io.NopCloser(&bytes.Buffer{}),
+		},
+		{
+			name: "if edge sends the body has data hint, don't set body to empty",
+			connectRequest: &pogs.ConnectRequest{
+				Dest: "http://test.com",
+				Metadata: []pogs.Metadata{
+					{
+						Key: "HttpHeader:Another-Header",
+						Val: "Misc",
+					},
+					{
+						Key: "HttpHost",
+						Val: "cf.host",
+					},
+					{
+						Key: "HttpMethod",
+						Val: "put",
+					},
+					{
+						Key: HTTPRequestBodyHintKey,
+						Val: RequestBodyHintHasData.String(),
+					},
+				},
+			},
+			req: &http.Request{
+				Method: "put",
+				URL: &url.URL{
+					Scheme: "http",
+					Host:   "test.com",
+				},
+				Proto:      "HTTP/1.1",
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+				Header: http.Header{
+					"Another-Header": []string{"Misc"},
+				},
+				ContentLength: 0,
+				Host:          "cf.host",
+				Body:          io.NopCloser(&bytes.Buffer{}),
+			},
+			body: io.NopCloser(&bytes.Buffer{}),
+		},
+		{
+			name: "if the http method usually has body, don't set body to empty",
+			connectRequest: &pogs.ConnectRequest{
+				Dest: "http://test.com",
+				Metadata: []pogs.Metadata{
+					{
+						Key: "HttpHeader:Another-Header",
+						Val: "Misc",
+					},
+					{
+						Key: "HttpHost",
+						Val: "cf.host",
+					},
+					{
+						Key: "HttpMethod",
+						Val: "post",
+					},
+				},
+			},
+			req: &http.Request{
+				Method: "post",
+				URL: &url.URL{
+					Scheme: "http",
+					Host:   "test.com",
+				},
+				Proto:      "HTTP/1.1",
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+				Header: http.Header{
+					"Another-Header": []string{"Misc"},
+				},
+				ContentLength: 0,
+				Host:          "cf.host",
+				Body:          io.NopCloser(&bytes.Buffer{}),
+			},
+			body: io.NopCloser(&bytes.Buffer{}),
+		},
 	}
 
 	log := zerolog.Nop()