Add compressed request body echo endpoint

httpbin/handlers.go

@@ -122,6 +122,56 @@ func (h *HTTPBin) RequestWithBodyDiscard(w http.ResponseWriter, r *http.Request)
 	writeJSON(http.StatusOK, w, resp)
 }
 
+// Echo returns the request body. If the incoming request uses gzip or deflate
+// Content-Encoding, the body is decompressed before echoing unless the raw
+// query parameter is set.
+func (h *HTTPBin) Echo(w http.ResponseWriter, r *http.Request) {
+	defer r.Body.Close()
+
+	var reader io.Reader = r.Body
+	encoding := strings.ToLower(r.Header.Get("Content-Encoding"))
+	contentType := r.Header.Get("Content-Type")
+	if contentType == "" {
+		contentType = textContentType
+	}
+
+	if !r.URL.Query().Has("raw") {
+		switch {
+		case strings.Contains(encoding, "gzip"):
+			gzr, err := gzip.NewReader(r.Body)
+			if err != nil {
+				writeError(w, http.StatusBadRequest, fmt.Errorf("error decoding gzip request body: %w", err))
+				return
+			}
+			defer gzr.Close()
+			reader = gzr
+
+		case strings.Contains(encoding, "deflate"):
+			zr, err := zlib.NewReader(r.Body)
+			if err != nil {
+				writeError(w, http.StatusBadRequest, fmt.Errorf("error decoding deflate request body: %w", err))
+				return
+			}
+			defer zr.Close()
+			reader = zr
+		}
+	}
+
+	// Read one byte past the limit so over-limit decoded bodies can be
+	// rejected instead of silently truncated.
+	body, err := io.ReadAll(io.LimitReader(reader, h.MaxBodySize+1))
+	if err != nil {
+		writeError(w, http.StatusBadRequest, fmt.Errorf("error reading request body: %w", err))
+		return
+	}
+	if int64(len(body)) > h.MaxBodySize {
+		writeError(w, http.StatusBadRequest, fmt.Errorf("request body exceeds maximum size of %d bytes", h.MaxBodySize))
+		return
+	}
+
+	writeResponse(w, http.StatusOK, contentType, body)
+}
+
 // Gzip returns a gzipped response
 func (h *HTTPBin) Gzip(w http.ResponseWriter, r *http.Request) {
 	var (

httpbin/handlers_test.go

@@ -56,6 +56,16 @@ type targetConfig struct {
 	MaxJSONLCount int64
 }
 
+type errorReadCloser struct{}
+
+func (errorReadCloser) Read(_ []byte) (int, error) {
+	return 0, io.ErrUnexpectedEOF
+}
+
+func (errorReadCloser) Close() error {
+	return nil
+}
+
 // configFromApp builds a [targetConfig] from an in-process [HTTPBin].
 func configFromApp(app *HTTPBin) targetConfig {
 	return targetConfig{
@@ -148,6 +158,8 @@ func TestIndex(t *testing.T) {
 			body := must.ReadAll(t, resp.Body)
 			assert.Contains(t, body, "go-httpbin", "body")
 			assert.Contains(t, body, prefix+"/get", "body")
+			assert.Contains(t, body, prefix+"/echo", "body")
+			assert.Contains(t, body, "?raw", "body")
 		})
 
 		t.Run("not found"+prefix, func(t *testing.T) {
@@ -593,6 +605,202 @@ func TestAnything(t *testing.T) {
 	})
 }
 
+func TestEcho(t *testing.T) {
+	t.Parallel()
+
+	app := setupTestApp(t)
+	overLimitBody := strings.Repeat("x", 65)
+
+	t.Run("plain body", func(t *testing.T) {
+		t.Parallel()
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), strings.NewReader("I am deflater mouse"))
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusOK)
+		assert.ContentType(t, resp, textContentType)
+		assert.BodyEquals(t, resp, "I am deflater mouse")
+	})
+
+	t.Run("preserves request content type", func(t *testing.T) {
+		t.Parallel()
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), strings.NewReader(`{"ok":true}`))
+		req.Header.Set("Content-Type", "application/json")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusOK)
+		assert.ContentType(t, resp, "application/json")
+		assert.BodyEquals(t, resp, `{"ok":true}`)
+	})
+
+	t.Run("gzip content encoding", func(t *testing.T) {
+		t.Parallel()
+
+		var buf bytes.Buffer
+		gzw := gzip.NewWriter(&buf)
+		_, err := gzw.Write([]byte("I am gzip mouse"))
+		assert.NilError(t, err)
+		assert.NilError(t, gzw.Close())
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), &buf)
+		req.Header.Set("Content-Encoding", "gzip")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusOK)
+		assert.ContentType(t, resp, textContentType)
+		assert.BodyEquals(t, resp, "I am gzip mouse")
+	})
+
+	t.Run("gzip content encoding raw", func(t *testing.T) {
+		t.Parallel()
+
+		var buf bytes.Buffer
+		gzw := gzip.NewWriter(&buf)
+		_, err := gzw.Write([]byte("I am raw gzip mouse"))
+		assert.NilError(t, err)
+		assert.NilError(t, gzw.Close())
+		compressedBody := append([]byte(nil), buf.Bytes()...)
+
+		req := newTestRequest(t, "POST", app.URL("/echo?raw"), bytes.NewReader(compressedBody))
+		req.Header.Set("Content-Encoding", "gzip")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusOK)
+		assert.ContentType(t, resp, textContentType)
+		body, err := io.ReadAll(resp.Body)
+		assert.NilError(t, err)
+		assert.DeepEqual(t, body, compressedBody, "raw echo body")
+	})
+
+	t.Run("invalid gzip content encoding", func(t *testing.T) {
+		t.Parallel()
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), strings.NewReader("not gzip"))
+		req.Header.Set("Content-Encoding", "gzip")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusBadRequest)
+	})
+
+	t.Run("invalid gzip content encoding raw", func(t *testing.T) {
+		t.Parallel()
+
+		req := newTestRequest(t, "POST", app.URL("/echo?raw"), strings.NewReader("not gzip"))
+		req.Header.Set("Content-Encoding", "gzip")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusOK)
+		assert.BodyEquals(t, resp, "not gzip")
+	})
+
+	t.Run("gzip content encoding exactly at decoded limit", func(t *testing.T) {
+		t.Parallel()
+
+		app := setupTestApp(t, WithMaxBodySize(64))
+		decodedBody := strings.Repeat("x", 64)
+
+		var buf bytes.Buffer
+		gzw := gzip.NewWriter(&buf)
+		_, err := gzw.Write([]byte(decodedBody))
+		assert.NilError(t, err)
+		assert.NilError(t, gzw.Close())
+		if buf.Len() >= 64 {
+			t.Fatalf("compressed test body must stay under MaxBodySize to exercise the decoded limit")
+		}
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), &buf)
+		req.Header.Set("Content-Encoding", "gzip")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusOK)
+		assert.BodyEquals(t, resp, decodedBody)
+	})
+
+	t.Run("gzip content encoding too big after decompression", func(t *testing.T) {
+		t.Parallel()
+
+		app := setupTestApp(t, WithMaxBodySize(64))
+		var buf bytes.Buffer
+		gzw := gzip.NewWriter(&buf)
+		_, err := gzw.Write([]byte(overLimitBody))
+		assert.NilError(t, err)
+		assert.NilError(t, gzw.Close())
+		if buf.Len() >= 64 {
+			t.Fatalf("compressed test body must stay under MaxBodySize to exercise the decompressed limit")
+		}
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), &buf)
+		req.Header.Set("Content-Encoding", "gzip")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusBadRequest)
+	})
+
+	t.Run("deflate content encoding", func(t *testing.T) {
+		t.Parallel()
+
+		var buf bytes.Buffer
+		zw := zlib.NewWriter(&buf)
+		_, err := zw.Write([]byte("I am deflate mouse"))
+		assert.NilError(t, err)
+		assert.NilError(t, zw.Close())
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), &buf)
+		req.Header.Set("Content-Encoding", "deflate")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusOK)
+		assert.ContentType(t, resp, textContentType)
+		assert.BodyEquals(t, resp, "I am deflate mouse")
+	})
+
+	t.Run("invalid deflate content encoding", func(t *testing.T) {
+		t.Parallel()
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), strings.NewReader("not deflate"))
+		req.Header.Set("Content-Encoding", "deflate")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusBadRequest)
+	})
+
+	t.Run("deflate content encoding too big after decompression", func(t *testing.T) {
+		t.Parallel()
+
+		app := setupTestApp(t, WithMaxBodySize(64))
+		var buf bytes.Buffer
+		zw := zlib.NewWriter(&buf)
+		_, err := zw.Write([]byte(overLimitBody))
+		assert.NilError(t, err)
+		assert.NilError(t, zw.Close())
+		if buf.Len() >= 64 {
+			t.Fatalf("compressed test body must stay under MaxBodySize to exercise the decompressed limit")
+		}
+
+		req := newTestRequest(t, "POST", app.URL("/echo"), &buf)
+		req.Header.Set("Content-Encoding", "deflate")
+		resp := mustDoRequest(t, app, req)
+
+		assert.StatusCode(t, resp, http.StatusBadRequest)
+	})
+
+	t.Run("body read error", func(t *testing.T) {
+		t.Parallel()
+
+		app := createApp()
+		req := httptest.NewRequest("POST", "/echo", nil)
+		req.Body = errorReadCloser{}
+		w := httptest.NewRecorder()
+
+		app.Echo(w, req)
+		resp := w.Result()
+
+		assert.StatusCode(t, resp, http.StatusBadRequest)
+		assert.BodyContains(t, resp, "error reading request body")
+	})
+}
+
 func testRequestWithBody(t *testing.T, app *appTestInfo, verb, path string) {
 	t.Run("BinaryBody", func(t *testing.T) {
 		t.Parallel()

httpbin/httpbin.go

@@ -194,6 +194,7 @@ func (h *HTTPBin) Handler() http.Handler {
 	mux.HandleFunc("/digest-auth/{qop}/{user}/{password}/{algorithm}", h.DigestAuth)
 	mux.HandleFunc("/drip", h.Drip)
 	mux.HandleFunc("/dump/request", h.DumpRequest)
+	mux.HandleFunc("/echo", h.Echo)
 	mux.HandleFunc("/env", h.Env)
 	mux.HandleFunc("/etag/{etag}", h.ETag)
 	mux.HandleFunc("/gzip", h.Gzip)

httpbin/static/index.html.tmpl

@@ -81,6 +81,7 @@
 <li><a href="{{.Prefix}}/digest-auth/auth/user/password/SHA-256"><code>{{.Prefix}}/digest-auth/:qop/:user/:password/:algorithm</code></a> Challenges HTTP Digest Auth using specified algorithm (MD5 or SHA-256)</li>
 <li><a href="{{.Prefix}}/drip?code=200&amp;numbytes=5&amp;duration=5"><code>{{.Prefix}}/drip?numbytes=n&amp;duration=s&amp;delay=s&amp;code=code</code></a> Drips data over the given duration after an optional initial delay, simulating a slow HTTP server.</li>
 <li><a href="{{.Prefix}}/dump/request"><code>{{.Prefix}}/dump/request</code></a> Returns the given request in its HTTP/1.x wire approximate representation.</li>
+<li><a href="{{.Prefix}}/echo"><code>{{.Prefix}}/echo</code></a> Echoes the request body as plain text, decompressing gzip or deflate request bodies unless <code>?raw</code> is set.</li>
 <li><a href="{{.Prefix}}/encoding/utf8"><code>{{.Prefix}}/encoding/utf8</code></a> Returns page containing UTF-8 data.</li>
 <li><a href="{{.Prefix}}/env"><code>{{.Prefix}}/env</code></a> Returns all environment variables named with <code>HTTPBIN_ENV_</code> prefix.</li>
 <li><a href="{{.Prefix}}/etag/etag"><code>{{.Prefix}}/etag/:etag</code></a> Assumes the resource has the given etag and responds to If-None-Match header with a 200 or 304 and If-Match with a 200 or 412 as appropriate.</li>