Add support for callback header (#8)

Exposed callback headers as defined in this recent change to the API: nexus-rpc/api#4
nexus-rpc · Mar 21, 2024 · 31b136e · 31b136e
1 parent ece9d41
commit 31b136e
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Showing 7 changed files with 52 additions and 19 deletions.
diff --git a/nexus/api.go b/nexus/api.go
@@ -114,12 +114,13 @@ func (h Header) Get(k string) string {
 	return h[strings.ToLower(k)]
 }
 
-func httpHeaderToContentHeader(httpHeader http.Header) Header {
+func prefixStrippedHTTPHeaderToNexusHeader(httpHeader http.Header, prefix string) Header {
 	header := Header{}
 	for k, v := range httpHeader {
-		if strings.HasPrefix(k, "Content-") {
+		lowerK := strings.ToLower(k)
+		if strings.HasPrefix(lowerK, prefix) {
 			// Nexus headers can only have single values, ignore multiple values.
-			header[strings.ToLower(k[8:])] = v[0]
+			header[lowerK[len(prefix):]] = v[0]
 		}
 	}
 	return header
@@ -132,13 +133,25 @@ func addContentHeaderToHTTPHeader(nexusHeader Header, httpHeader http.Header) ht
 	return httpHeader
 }
 
-func httpHeaderToNexusHeader(httpHeader http.Header) Header {
+func addCallbackHeaderToHTTPHeader(nexusHeader Header, httpHeader http.Header) http.Header {
+	for k, v := range nexusHeader {
+		httpHeader.Set("Nexus-Callback-"+k, v)
+	}
+	return httpHeader
+}
+
+func httpHeaderToNexusHeader(httpHeader http.Header, excludePrefixes ...string) Header {
 	header := Header{}
+headerLoop:
 	for k, v := range httpHeader {
-		if !strings.HasPrefix(k, "Content-") {
-			// Nexus headers can only have single values, ignore multiple values.
-			header[strings.ToLower(k)] = v[0]
+		lowerK := strings.ToLower(k)
+		for _, prefix := range excludePrefixes {
+			if strings.HasPrefix(lowerK, prefix) {
+				continue headerLoop
+			}
 		}
+		// Nexus headers can only have single values, ignore multiple values.
+		header[lowerK] = v[0]
 	}
 	return header
 }

diff --git a/nexus/client.go b/nexus/client.go
@@ -193,6 +193,7 @@ func (c *Client) StartOperation(ctx context.Context, operation string, input any
 	request.Header.Set(headerRequestID, options.RequestID)
 	request.Header.Set(headerUserAgent, userAgent)
 	addContentHeaderToHTTPHeader(reader.Header, request.Header)
+	addCallbackHeaderToHTTPHeader(options.CallbackHeader, request.Header)
 
 	response, err := c.options.HTTPCaller(request)
 	if err != nil {
@@ -205,7 +206,7 @@ func (c *Client) StartOperation(ctx context.Context, operation string, input any
 				serializer: c.options.Serializer,
 				Reader: &Reader{
 					response.Body,
-					httpHeaderToContentHeader(response.Header),
+					prefixStrippedHTTPHeaderToNexusHeader(response.Header, "content-"),
 				},
 			},
 		}, nil
@@ -259,6 +260,9 @@ type ExecuteOperationOptions struct {
 	// Even though Client.ExecuteOperation waits for operation completion, some applications may want to set this
 	// callback as a fallback mechanism.
 	CallbackURL string
+	// Optional header fields set by a client that are required to be attached to the callback request when an
+	// asynchronous operation completes.
+	CallbackHeader Header
 	// Request ID that may be used by the server handler to dedupe this start request.
 	// By default a v4 UUID will be generated by the client.
 	RequestID string
@@ -289,9 +293,10 @@ type ExecuteOperationOptions struct {
 // free up the underlying connection.
 func (c *Client) ExecuteOperation(ctx context.Context, operation string, input any, options ExecuteOperationOptions) (*LazyValue, error) {
 	so := StartOperationOptions{
-		CallbackURL: options.CallbackURL,
-		RequestID:   options.RequestID,
-		Header:      options.Header,
+		CallbackURL:    options.CallbackURL,
+		CallbackHeader: options.CallbackHeader,
+		RequestID:      options.RequestID,
+		Header:         options.Header,
 	}
 	result, err := c.StartOperation(ctx, operation, input, so)
 	if err != nil {

diff --git a/nexus/completion.go b/nexus/completion.go
@@ -178,7 +178,7 @@ func (h *completionHTTPHandler) ServeHTTP(writer http.ResponseWriter, request *h
 			serializer: h.options.Serializer,
 			Reader: &Reader{
 				request.Body,
-				httpHeaderToContentHeader(request.Header),
+				prefixStrippedHTTPHeaderToNexusHeader(request.Header, "content-"),
 			},
 		}
 	default:

diff --git a/nexus/handle.go b/nexus/handle.go
@@ -107,7 +107,7 @@ func (h *OperationHandle[T]) GetResult(ctx context.Context, options GetOperation
 			serializer: h.client.options.Serializer,
 			Reader: &Reader{
 				response.Body,
-				httpHeaderToContentHeader(response.Header),
+				prefixStrippedHTTPHeaderToNexusHeader(response.Header, "content-"),
 			},
 		}
 		if _, ok := any(result).(*LazyValue); ok {

diff --git a/nexus/options.go b/nexus/options.go
@@ -18,6 +18,9 @@ type StartOperationOptions struct {
 	//
 	// Implement a [CompletionHandler] and expose it as an HTTP handler to handle async completions.
 	CallbackURL string
+	// Optional header fields set by a client that are required to be attached to the callback request when an
+	// asynchronous operation completes.
+	CallbackHeader Header
 	// Request ID that may be used by the server handler to dedupe a start request.
 	// By default a v4 UUID will be generated by the client.
 	RequestID string

diff --git a/nexus/server.go b/nexus/server.go
@@ -276,15 +276,16 @@ func (h *httpHandler) startOperation(writer http.ResponseWriter, request *http.R
 		return
 	}
 	options := StartOperationOptions{
-		RequestID:   request.Header.Get(headerRequestID),
-		CallbackURL: request.URL.Query().Get(queryCallbackURL),
-		Header:      httpHeaderToNexusHeader(request.Header),
+		RequestID:      request.Header.Get(headerRequestID),
+		CallbackURL:    request.URL.Query().Get(queryCallbackURL),
+		CallbackHeader: prefixStrippedHTTPHeaderToNexusHeader(request.Header, "nexus-callback-"),
+		Header:         httpHeaderToNexusHeader(request.Header, "content-", "nexus-callback-"),
 	}
 	value := &LazyValue{
 		serializer: h.options.Serializer,
 		Reader: &Reader{
 			request.Body,
-			httpHeaderToContentHeader(request.Header),
+			prefixStrippedHTTPHeaderToNexusHeader(request.Header, "content-"),
 		},
 	}
 	response, err := h.options.Handler.StartOperation(request.Context(), operation, value, options)

diff --git a/nexus/start_test.go b/nexus/start_test.go
@@ -25,9 +25,19 @@ func (h *successHandler) StartOperation(ctx context.Context, operation string, i
 	if options.CallbackURL != "http://test/callback" {
 		return nil, HandlerErrorf(HandlerErrorTypeBadRequest, "unexpected callback URL: %s", options.CallbackURL)
 	}
+	if options.CallbackHeader.Get("callback-test") != "ok" {
+		return nil, HandlerErrorf(
+			HandlerErrorTypeBadRequest,
+			"invalid 'callback-test' callback header: %q",
+			options.CallbackHeader.Get("callback-test"),
+		)
+	}
 	if options.Header.Get("test") != "ok" {
 		return nil, HandlerErrorf(HandlerErrorTypeBadRequest, "invalid 'test' header: %q", options.Header.Get("test"))
 	}
+	if options.Header.Get("nexus-callback-callback-test") != "" {
+		return nil, HandlerErrorf(HandlerErrorTypeBadRequest, "callback header not omitted from options Header")
+	}
 	if options.Header.Get("User-Agent") != userAgent {
 		return nil, HandlerErrorf(HandlerErrorTypeBadRequest, "invalid 'User-Agent' header: %q", options.Header.Get("User-Agent"))
 	}
@@ -42,8 +52,9 @@ func TestSuccess(t *testing.T) {
 	requestBody := []byte{0x00, 0x01}
 
 	response, err := client.ExecuteOperation(ctx, "i need to/be escaped", requestBody, ExecuteOperationOptions{
-		CallbackURL: "http://test/callback",
-		Header:      Header{"test": "ok"},
+		CallbackURL:    "http://test/callback",
+		CallbackHeader: Header{"callback-test": "ok"},
+		Header:         Header{"test": "ok"},
 	})
 	require.NoError(t, err)
 	var responseBody []byte