[feat](server, client): implement streaming-based HTTP tunnel with DTLS sessions

- Replaced single-envelope HTTP handling with stream-based tunneling (`StreamOpen`, `StreamData`, and `StreamClose`) for HTTP-over-DTLS. - Added unique StreamID generation for per-session HTTP requests. - Improved client and server logic for handling chunked body transmissions and reverse stream responses. - Enhanced pseudo-header handling for HTTP metadata in tunneling. - Updated error handling for local HTTP failures, ensuring proper stream-based responses.
2025-12-09 13:25:44 +09:00 · 2025-12-08 23:05:45 +09:00
parent 798ad75e39
commit 5e94dd7aa9
2 changed files with 544 additions and 96 deletions
--- a/internal/proxy/client.go
+++ b/internal/proxy/client.go
@@ -8,6 +8,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"strconv"
 	"time"

 	"github.com/dalbodeule/hop-gate/internal/dtls"
@@ -50,10 +51,11 @@ func NewClientProxy(logger logging.Logger, localTarget string) *ClientProxy {
 	}
 }

-// StartLoop 는 DTLS 세션에서 protocol.Envelope 를 읽고, HTTP 요청의 경우 로컬 HTTP 요청을 수행한 뒤
-// protocol.Envelope(HTTP 응답 포함)을 다시 세션으로 쓰는 루프를 실행합니다. (ko)
-// StartLoop reads protocol.Envelope messages from the DTLS session; for HTTP messages it
-// performs local HTTP requests and writes back HTTP responses wrapped in an Envelope. (en)
+// StartLoop 는 DTLS 세션에서 protocol.Envelope 를 읽고, HTTP/스트림 요청의 경우 로컬 HTTP 요청을 수행한 뒤
+// protocol.Envelope(HTTP/스트림 응답 포함)을 다시 세션으로 쓰는 루프를 실행합니다. (ko)
+// StartLoop reads protocol.Envelope messages from the DTLS session; for HTTP/stream
+// messages it performs local HTTP requests and writes back responses over the DTLS
+// tunnel. (en)
 func (p *ClientProxy) StartLoop(ctx context.Context, sess dtls.Session) error {
 	if ctx == nil {
 		ctx = context.Background()
@@ -92,60 +94,348 @@ func (p *ClientProxy) StartLoop(ctx context.Context, sess dtls.Session) error {
 			return err
 		}

-		// 현재는 HTTP 타입만 지원하며, 그 외 타입은 에러로 처리합니다.
-		if env.Type != protocol.MessageTypeHTTP || env.HTTPRequest == nil {
+		switch env.Type {
+		case protocol.MessageTypeHTTP:
+			if err := p.handleHTTPEnvelope(ctx, sess, &env); err != nil {
+				log.Error("failed to handle http envelope", logging.Fields{
+					"error": err.Error(),
+				})
+				return err
+			}
+		case protocol.MessageTypeStreamOpen:
+			if err := p.handleStreamRequest(ctx, sess, &env); err != nil {
+				log.Error("failed to handle stream http envelope", logging.Fields{
+					"error": err.Error(),
+				})
+				return err
+			}
+		default:
 			log.Error("received unsupported envelope type from server", logging.Fields{
 				"type": env.Type,
 			})
-			return fmt.Errorf("unsupported envelope type %q or missing http_request", env.Type)
+			return fmt.Errorf("unsupported envelope type %q", env.Type)
 		}
+	}
+}

-		req := env.HTTPRequest
+// handleHTTPEnvelope 는 기존 단일 HTTP 요청/응답 Envelope 경로를 처리합니다. (ko)
+// handleHTTPEnvelope handles the legacy single HTTP request/response envelope path. (en)
+func (p *ClientProxy) handleHTTPEnvelope(ctx context.Context, sess dtls.Session, env *protocol.Envelope) error {
+	if env.HTTPRequest == nil {
+		return fmt.Errorf("http envelope missing http_request payload")
+	}

-		start := time.Now()
-		logReq := log.With(logging.Fields{
-			"request_id":   req.RequestID,
-			"service":      req.ServiceName,
-			"method":       req.Method,
-			"url":          req.URL,
-			"client_id":    req.ClientID,
-			"local_target": p.LocalTarget,
-		})
-		logReq.Info("received http envelope from server", nil)
+	req := env.HTTPRequest
+	log := p.Logger
+	start := time.Now()

-		resp := protocol.Response{
-			RequestID: req.RequestID,
-			Header:    make(map[string][]string),
-		}
+	logReq := log.With(logging.Fields{
+		"request_id":   req.RequestID,
+		"service":      req.ServiceName,
+		"method":       req.Method,
+		"url":          req.URL,
+		"client_id":    req.ClientID,
+		"local_target": p.LocalTarget,
+	})
+	logReq.Info("received http envelope from server", nil)

-		// 로컬 HTTP 요청 수행
-		if err := p.forwardToLocal(ctx, req, &resp); err != nil {
-			resp.Status = http.StatusBadGateway
-			resp.Error = err.Error()
-			logReq.Error("local http request failed", logging.Fields{
-				"error": err.Error(),
-			})
-		}
+	resp := protocol.Response{
+		RequestID: req.RequestID,
+		Header:    make(map[string][]string),
+	}

-		// HTTP 응답을 Envelope 로 감싸서 서버로 전송합니다.
-		respEnv := protocol.Envelope{
-			Type:         protocol.MessageTypeHTTP,
-			HTTPResponse: &resp,
-		}
-
-		if err := codec.Encode(sess, &respEnv); err != nil {
-			logReq.Error("failed to encode http response envelope", logging.Fields{
-				"error": err.Error(),
-			})
-			return err
-		}
-
-		logReq.Info("http response envelope sent to server", logging.Fields{
-			"status":     resp.Status,
-			"elapsed_ms": time.Since(start).Milliseconds(),
-			"error":      resp.Error,
+	// 로컬 HTTP 요청 수행
+	if err := p.forwardToLocal(ctx, req, &resp); err != nil {
+		resp.Status = http.StatusBadGateway
+		resp.Error = err.Error()
+		logReq.Error("local http request failed", logging.Fields{
+			"error": err.Error(),
 		})
 	}
+
+	// HTTP 응답을 Envelope 로 감싸서 서버로 전송합니다.
+	respEnv := protocol.Envelope{
+		Type:         protocol.MessageTypeHTTP,
+		HTTPResponse: &resp,
+	}
+
+	if err := protocol.DefaultCodec.Encode(sess, &respEnv); err != nil {
+		logReq.Error("failed to encode http response envelope", logging.Fields{
+			"error": err.Error(),
+		})
+		return err
+	}
+
+	logReq.Info("http response envelope sent to server", logging.Fields{
+		"status":     resp.Status,
+		"elapsed_ms": time.Since(start).Milliseconds(),
+		"error":      resp.Error,
+	})
+
+	return nil
+}
+
+// handleStreamRequest 는 StreamOpen/StreamData/StreamClose 기반 HTTP 요청/응답 스트림을 처리합니다. (ko)
+// handleStreamRequest handles an HTTP request/response exchange using StreamOpen/StreamData/StreamClose frames. (en)
+func (p *ClientProxy) handleStreamRequest(ctx context.Context, sess dtls.Session, openEnv *protocol.Envelope) error {
+	codec := protocol.DefaultCodec
+	log := p.Logger
+
+	so := openEnv.StreamOpen
+	if so == nil {
+		return fmt.Errorf("stream_open envelope missing payload")
+	}
+
+	streamID := so.ID
+
+	// Pseudo-header 에서 HTTP 메타데이터를 추출합니다. (ko)
+	// Extract HTTP metadata from pseudo-headers. (en)
+	method := firstHeaderValue(so.Header, protocol.HeaderKeyMethod, http.MethodGet)
+	urlStr := firstHeaderValue(so.Header, protocol.HeaderKeyURL, "/")
+	_ = firstHeaderValue(so.Header, protocol.HeaderKeyHost, "")
+
+	if p.LocalTarget == "" {
+		return fmt.Errorf("local target is empty")
+	}
+
+	u, err := url.Parse(urlStr)
+	if err != nil {
+		return fmt.Errorf("parse url from stream_open: %w", err)
+	}
+	u.Scheme = "http"
+	u.Host = p.LocalTarget
+
+	// 로컬 HTTP 요청용 헤더 맵을 생성하면서 pseudo-header 는 제거합니다. (ko)
+	// Build local HTTP header map while stripping pseudo-headers. (en)
+	httpHeader := make(http.Header, len(so.Header))
+	for k, vs := range so.Header {
+		if k == protocol.HeaderKeyMethod ||
+			k == protocol.HeaderKeyURL ||
+			k == protocol.HeaderKeyHost ||
+			k == protocol.HeaderKeyStatus {
+			continue
+		}
+		for _, v := range vs {
+			httpHeader.Add(k, v)
+		}
+	}
+
+	// 요청 바디를 StreamData/StreamClose 프레임에서 모두 읽어 메모리에 적재합니다. (ko)
+	// Read the entire request body from StreamData/StreamClose frames into memory. (en)
+	var bodyBuf bytes.Buffer
+	for {
+		var env protocol.Envelope
+		if err := codec.Decode(sess, &env); err != nil {
+			if err == io.EOF {
+				return fmt.Errorf("unexpected EOF while reading stream request body")
+			}
+			return fmt.Errorf("decode stream request frame: %w", err)
+		}
+
+		switch env.Type {
+		case protocol.MessageTypeStreamData:
+			sd := env.StreamData
+			if sd == nil {
+				return fmt.Errorf("stream_data payload is nil")
+			}
+			if sd.ID != streamID {
+				return fmt.Errorf("stream_data for unexpected stream id %q (expected %q)", sd.ID, streamID)
+			}
+			if len(sd.Data) > 0 {
+				if _, err := bodyBuf.Write(sd.Data); err != nil {
+					return fmt.Errorf("buffer stream_data: %w", err)
+				}
+			}
+		case protocol.MessageTypeStreamClose:
+			sc := env.StreamClose
+			if sc == nil {
+				return fmt.Errorf("stream_close payload is nil")
+			}
+			if sc.ID != streamID {
+				return fmt.Errorf("stream_close for unexpected stream id %q (expected %q)", sc.ID, streamID)
+			}
+			// sc.Error 는 최소 구현에서는 로컬 요청 에러와 별도로 취급하지 않습니다. (ko)
+			// For the minimal implementation we do not surface sc.Error here. (en)
+			goto haveBody
+		default:
+			return fmt.Errorf("unexpected envelope type %q while reading stream request body", env.Type)
+		}
+	}
+
+haveBody:
+	bodyBytes := bodyBuf.Bytes()
+
+	// 로컬 HTTP 요청 생성 (stream 기반 요청을 실제 HTTP 요청으로 변환). (ko)
+	// Build the local HTTP request from the stream-based metadata and body. (en)
+	req, err := http.NewRequestWithContext(ctx, method, u.String(), nil)
+	if err != nil {
+		return fmt.Errorf("create http request from stream: %w", err)
+	}
+	if len(bodyBytes) > 0 {
+		buf := bytes.NewReader(bodyBytes)
+		req.Body = io.NopCloser(buf)
+		req.ContentLength = int64(len(bodyBytes))
+	}
+	req.Header = httpHeader
+
+	start := time.Now()
+	logReq := log.With(logging.Fields{
+		"request_id":   string(streamID),
+		"service":      so.Service,
+		"method":       method,
+		"url":          urlStr,
+		"stream_id":    string(streamID),
+		"local_target": p.LocalTarget,
+	})
+	logReq.Info("received stream_open envelope from server", nil)
+
+	res, err := p.HTTPClient.Do(req)
+	if err != nil {
+		// 로컬 요청 실패 시, 502 + 에러 메시지를 스트림 응답으로 전송합니다. (ko)
+		// On local request failure, send a 502 response over the stream. (en)
+		errMsg := fmt.Sprintf("perform http request: %v", err)
+		streamRespHeader := map[string][]string{
+			"Content-Type":           {"text/plain; charset=utf-8"},
+			protocol.HeaderKeyStatus: {strconv.Itoa(http.StatusBadGateway)},
+		}
+		respOpen := protocol.Envelope{
+			Type: protocol.MessageTypeStreamOpen,
+			StreamOpen: &protocol.StreamOpen{
+				ID:         streamID,
+				Service:    so.Service,
+				TargetAddr: so.TargetAddr,
+				Header:     streamRespHeader,
+			},
+		}
+		if err2 := codec.Encode(sess, &respOpen); err2 != nil {
+			logReq.Error("failed to encode stream response open envelope (error path)", logging.Fields{
+				"error": err2.Error(),
+			})
+			return err2
+		}
+
+		dataEnv := protocol.Envelope{
+			Type: protocol.MessageTypeStreamData,
+			StreamData: &protocol.StreamData{
+				ID:   streamID,
+				Seq:  0,
+				Data: []byte("HopGate: " + errMsg),
+			},
+		}
+		if err2 := codec.Encode(sess, &dataEnv); err2 != nil {
+			logReq.Error("failed to encode stream response data envelope (error path)", logging.Fields{
+				"error": err2.Error(),
+			})
+			return err2
+		}
+
+		closeEnv := protocol.Envelope{
+			Type: protocol.MessageTypeStreamClose,
+			StreamClose: &protocol.StreamClose{
+				ID:    streamID,
+				Error: errMsg,
+			},
+		}
+		if err2 := codec.Encode(sess, &closeEnv); err2 != nil {
+			logReq.Error("failed to encode stream response close envelope (error path)", logging.Fields{
+				"error": err2.Error(),
+			})
+			return err2
+		}
+
+		logReq.Error("local http request failed (stream)", logging.Fields{
+			"error": err.Error(),
+		})
+		return nil
+	}
+	defer res.Body.Close()
+
+	// 응답을 StreamOpen + StreamData(4KiB chunk) + StreamClose 프레임으로 전송합니다. (ko)
+	// Send the response as StreamOpen + StreamData (4KiB chunks) + StreamClose frames. (en)
+
+	// 응답 헤더 맵을 복사하고 상태 코드를 pseudo-header 로 추가합니다. (ko)
+	// Copy response headers and attach status code as a pseudo-header. (en)
+	streamRespHeader := make(map[string][]string, len(res.Header)+1)
+	for k, vs := range res.Header {
+		streamRespHeader[k] = append([]string(nil), vs...)
+	}
+	statusCode := res.StatusCode
+	if statusCode == 0 {
+		statusCode = http.StatusOK
+	}
+	streamRespHeader[protocol.HeaderKeyStatus] = []string{strconv.Itoa(statusCode)}
+
+	respOpen := protocol.Envelope{
+		Type: protocol.MessageTypeStreamOpen,
+		StreamOpen: &protocol.StreamOpen{
+			ID:         streamID,
+			Service:    so.Service,
+			TargetAddr: so.TargetAddr,
+			Header:     streamRespHeader,
+		},
+	}
+
+	if err := codec.Encode(sess, &respOpen); err != nil {
+		logReq.Error("failed to encode stream response open envelope", logging.Fields{
+			"error": err.Error(),
+		})
+		return err
+	}
+
+	// 응답 바디를 4KiB(StreamChunkSize) 단위로 잘라 StreamData 프레임으로 전송합니다. (ko)
+	// Chunk the response body into 4KiB (StreamChunkSize) StreamData frames. (en)
+	var seq uint64
+	chunk := make([]byte, protocol.StreamChunkSize)
+	for {
+		n, err := res.Body.Read(chunk)
+		if n > 0 {
+			dataCopy := append([]byte(nil), chunk[:n]...)
+			dataEnv := protocol.Envelope{
+				Type: protocol.MessageTypeStreamData,
+				StreamData: &protocol.StreamData{
+					ID:   streamID,
+					Seq:  seq,
+					Data: dataCopy,
+				},
+			}
+			if err2 := codec.Encode(sess, &dataEnv); err2 != nil {
+				logReq.Error("failed to encode stream response data envelope", logging.Fields{
+					"error": err2.Error(),
+				})
+				return err2
+			}
+			seq++
+		}
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return fmt.Errorf("read http response body for streaming: %w", err)
+		}
+	}
+
+	closeEnv := protocol.Envelope{
+		Type: protocol.MessageTypeStreamClose,
+		StreamClose: &protocol.StreamClose{
+			ID:    streamID,
+			Error: "",
+		},
+	}
+
+	if err := codec.Encode(sess, &closeEnv); err != nil {
+		logReq.Error("failed to encode stream response close envelope", logging.Fields{
+			"error": err.Error(),
+		})
+		return err
+	}
+
+	logReq.Info("stream http response sent to server", logging.Fields{
+		"status":     statusCode,
+		"elapsed_ms": time.Since(start).Milliseconds(),
+		"error":      "",
+	})
+
+	return nil
 }

 // forwardToLocal 는 protocol.Request 를 로컬 HTTP 요청으로 변환하고 protocol.Response 를 채웁니다. (ko)
@@ -240,3 +530,15 @@ func (p *ClientProxy) forwardToLocal(ctx context.Context, preq *protocol.Request

 	return nil
 }
+
+// firstHeaderValue 는 주어진 키의 첫 번째 헤더 값을 반환하고, 없으면 기본값을 반환합니다. (ko)
+// firstHeaderValue returns the first header value for a key, or a default if absent. (en)
+func firstHeaderValue(hdr map[string][]string, key, def string) string {
+	if hdr == nil {
+		return def
+	}
+	if vs, ok := hdr[key]; ok && len(vs) > 0 {
+		return vs[0]
+	}
+	return def
+}