fix: download LINE official account images

Author: highesttt

pkg/connector/handlers/image.go

@@ -20,57 +20,56 @@ func (h *Handler) ConvertImage(ctx context.Context, portal *bridgev2.Portal, int
 	}
 
 	client := h.NewClient()
-	oid := data.ContentMetadata["OID"]
-	isPlainMedia := oid == ""
-
-	// For plain media, the image is stored at r/talk/m/{messageID}
-	if isPlainMedia {
-		oid = data.ID
-	}
-
-	if oid == "" {
+	downloadSource := lineImageDownloadSource(data)
+	if downloadSource.publicPath == "" && downloadSource.oid == "" {
 		return nil, nil
 	}
 
 	mediaCategory := lineMediaCategory(data.ContentMetadata)
-	downloadOptions := lineOBSDownloadOptions(data.ContentMetadata, isPlainMedia)
-	talkMetaMessageID := obsTalkMetaMessageID(data.ID, isPlainMedia)
+	downloadOptions := lineOBSDownloadOptions(data.ContentMetadata, downloadSource.isPlainMedia)
+	talkMetaMessageID := obsTalkMetaMessageID(data.ID, downloadSource.isPlainMedia)
 
 	var imgData []byte
 	var err error
 	dlStart := time.Now()
 	h.Log.Debug().
-		Str("oid", oid).
+		Str("oid", downloadSource.oid).
 		Str("msg_id", data.ID).
 		Str("tid", downloadOptions.TID).
 		Str("media_category", mediaCategory).
 		Bool("has_obs_pop", downloadOptions.OBSPop != "").
-		Bool("plain_media", isPlainMedia).
+		Bool("plain_media", downloadSource.isPlainMedia).
+		Bool("public_resource", downloadSource.publicPath != "").
 		Msg("Downloading image from LINE OBS")
-	if isPlainMedia {
-		imgData, err = client.DownloadOBSWithSIDOptions(ctx, oid, talkMetaMessageID, "m", downloadOptions)
+	if downloadSource.publicPath != "" {
+		imgData, err = client.DownloadOBSPublicResource(ctx, downloadSource.publicPath)
+	} else if downloadSource.isPlainMedia {
+		imgData, err = client.DownloadOBSWithSIDOptions(ctx, downloadSource.oid, talkMetaMessageID, "m", downloadOptions)
 	} else {
-		imgData, err = client.DownloadOBSWithOptions(ctx, oid, talkMetaMessageID, downloadOptions)
+		imgData, err = client.DownloadOBSWithOptions(ctx, downloadSource.oid, talkMetaMessageID, downloadOptions)
 	}
 
 	// Refresh token if we get a 401
-	if newClient, ok := h.tryRecoverClient(ctx, client, err); ok {
-		client = newClient
-		if isPlainMedia {
-			imgData, err = client.DownloadOBSWithSIDOptions(ctx, oid, talkMetaMessageID, "m", downloadOptions)
-		} else {
-			imgData, err = client.DownloadOBSWithOptions(ctx, oid, talkMetaMessageID, downloadOptions)
+	if downloadSource.publicPath == "" {
+		if newClient, ok := h.tryRecoverClient(ctx, client, err); ok {
+			client = newClient
+			if downloadSource.isPlainMedia {
+				imgData, err = client.DownloadOBSWithSIDOptions(ctx, downloadSource.oid, talkMetaMessageID, "m", downloadOptions)
+			} else {
+				imgData, err = client.DownloadOBSWithOptions(ctx, downloadSource.oid, talkMetaMessageID, downloadOptions)
+			}
 		}
+		h.handleFinalAuthError(ctx, client, err)
 	}
-	h.handleFinalAuthError(ctx, client, err)
 	downloadDuration := time.Since(dlStart)
 
 	if err != nil {
 		h.Log.Warn().
 			Err(err).
-			Str("oid", oid).
+			Str("oid", downloadSource.oid).
 			Str("msg_id", data.ID).
-			Bool("plain_media", isPlainMedia).
+			Bool("plain_media", downloadSource.isPlainMedia).
+			Bool("public_resource", downloadSource.publicPath != "").
 			Dur("download_duration", downloadDuration).
 			Msg("Failed to download image from OBS")
 		return mediaDownloadFailure("Image", err, relatesTo)
@@ -147,6 +146,26 @@ func (h *Handler) ConvertImage(ctx context.Context, portal *bridgev2.Portal, int
 	}, nil
 }
 
+type imageDownloadSource struct {
+	publicPath   string
+	oid          string
+	isPlainMedia bool
+}
+
+func lineImageDownloadSource(data line.Message) imageDownloadSource {
+	if publicPath := data.ContentMetadata["DOWNLOAD_URL"]; publicPath != "" {
+		return imageDownloadSource{publicPath: publicPath}
+	}
+
+	oid := data.ContentMetadata["OID"]
+	if oid != "" {
+		return imageDownloadSource{oid: oid}
+	}
+
+	// For plain media, the image is stored at r/talk/m/{messageID}.
+	return imageDownloadSource{oid: data.ID, isPlainMedia: true}
+}
+
 func lineMediaCategory(metadata map[string]string) string {
 	if metadata == nil || metadata["MEDIA_CONTENT_INFO"] == "" {
 		return ""

pkg/connector/handlers/image_test.go

@@ -0,0 +1,39 @@
+package handlers
+
+import (
+	"testing"
+
+	"github.com/highesttt/matrix-line-messenger/pkg/line"
+)
+
+func TestLineImageDownloadSourcePrefersPublicResource(t *testing.T) {
+	source := lineImageDownloadSource(line.Message{
+		ID: "message-id",
+		ContentMetadata: map[string]string{
+			"DOWNLOAD_URL": "/r/official/business-image",
+			"OID":          "ignored-private-oid",
+		},
+	})
+
+	if source.publicPath != "/r/official/business-image" {
+		t.Fatalf("public path = %q", source.publicPath)
+	}
+	if source.oid != "" || source.isPlainMedia {
+		t.Fatalf("source = %#v, want public resource only", source)
+	}
+}
+
+func TestLineImageDownloadSourcePrivateAndPlainFallbacks(t *testing.T) {
+	privateSource := lineImageDownloadSource(line.Message{
+		ID:              "message-id",
+		ContentMetadata: map[string]string{"OID": "private-oid"},
+	})
+	if privateSource.publicPath != "" || privateSource.oid != "private-oid" || privateSource.isPlainMedia {
+		t.Fatalf("private source = %#v", privateSource)
+	}
+
+	plainSource := lineImageDownloadSource(line.Message{ID: "message-id"})
+	if plainSource.publicPath != "" || plainSource.oid != "message-id" || !plainSource.isPlainMedia {
+		t.Fatalf("plain source = %#v", plainSource)
+	}
+}

pkg/line/client.go

@@ -716,6 +716,45 @@ func (c *Client) DownloadOBSWithSIDOptions(ctx context.Context, oid string, mess
 	return c.downloadOBSWithServiceAndSIDOptions(ctx, "talk", sid, oid, messageID, opts)
 }
 
+// DownloadOBSPublicResource downloads a public OBS resource referenced by
+// message content metadata. LINE Chrome uses DOWNLOAD_URL directly and skips
+// object_info.obs and the private OBS authorization header mapper.
+func (c *Client) DownloadOBSPublicResource(ctx context.Context, resourcePath string) ([]byte, error) {
+	parsedPath, err := url.Parse(resourcePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse public OBS resource path: %w", err)
+	}
+	if parsedPath.IsAbs() || parsedPath.Host != "" || !strings.HasPrefix(parsedPath.Path, "/") {
+		return nil, errors.New("public OBS resource must be an absolute path")
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, OBSBaseURL+resourcePath, nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create public OBS resource request: %w", err)
+	}
+	req.Header.Set("User-Agent", UserAgent)
+
+	resp, err := c.obsHTTPClient().Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("public OBS resource request failed: %w", err)
+	}
+	body, readErr := io.ReadAll(resp.Body)
+	resp.Body.Close()
+	if readErr != nil {
+		return nil, fmt.Errorf("failed to read public OBS resource response: %w", readErr)
+	}
+	switch resp.StatusCode {
+	case http.StatusOK:
+		return body, nil
+	case http.StatusAccepted:
+		return nil, ErrOBSEncodingIncomplete
+	case http.StatusNotFound:
+		return nil, ErrOBSObjectNotFound
+	default:
+		return nil, fmt.Errorf("public OBS resource download failed (%d): %s", resp.StatusCode, string(body))
+	}
+}
+
 // DownloadOBSResource retrieves a non-talk resource using the service, SID,
 // and OID supplied by LINE metadata. Album post previews use service "album"
 // and SID "a".

pkg/line/obs_test.go

@@ -88,6 +88,73 @@ func TestDownloadOBSPlainMatchesChromeRequestFlow(t *testing.T) {
 	}
 }
 
+func TestDownloadOBSPublicResourceMatchesChromeRequestFlow(t *testing.T) {
+	var request *http.Request
+	client := NewClient("line-token-that-must-not-be-used")
+	client.OBSClient = &http.Client{
+		Transport: roundTripFunc(func(req *http.Request) (*http.Response, error) {
+			request = req
+			return obsResponse(http.StatusOK, "business-image"), nil
+		}),
+	}
+
+	data, err := client.DownloadOBSPublicResource(
+		context.Background(),
+		"/r/official/image-id?public=resource",
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(data) != "business-image" {
+		t.Fatalf("data = %q, want business-image", data)
+	}
+	if request == nil {
+		t.Fatal("public resource request was not made")
+	}
+	if request.URL.Scheme != "https" || request.URL.Host != "obs.line-apps.com" {
+		t.Fatalf("request URL origin = %s://%s", request.URL.Scheme, request.URL.Host)
+	}
+	if request.URL.Path != "/r/official/image-id" || request.URL.RawQuery != "public=resource" {
+		t.Fatalf("request URL = %s", request.URL.String())
+	}
+	if request.Header.Get("X-Line-Access") != "" {
+		t.Fatal("public resource request unexpectedly included X-Line-Access")
+	}
+	if request.Header.Get("X-Line-Application") != "" {
+		t.Fatal("public resource request unexpectedly included X-Line-Application")
+	}
+	if request.Header.Get("X-Talk-Meta") != "" {
+		t.Fatal("public resource request unexpectedly included X-Talk-Meta")
+	}
+}
+
+func TestDownloadOBSPublicResourceRejectsExternalURL(t *testing.T) {
+	client := NewClient("line-token")
+	for _, resourcePath := range []string{
+		"https://example.com/image",
+		"//example.com/image",
+		"relative/image",
+	} {
+		if _, err := client.DownloadOBSPublicResource(context.Background(), resourcePath); err == nil {
+			t.Fatalf("resource path %q was accepted", resourcePath)
+		}
+	}
+}
+
+func TestDownloadOBSPublicResourceClassifiesMissingObject(t *testing.T) {
+	client := NewClient("line-token")
+	client.OBSClient = &http.Client{
+		Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
+			return obsResponse(http.StatusNotFound, "not found"), nil
+		}),
+	}
+
+	_, err := client.DownloadOBSPublicResource(context.Background(), "/r/official/missing")
+	if !errors.Is(err, ErrOBSObjectNotFound) {
+		t.Fatalf("err = %v, want ErrOBSObjectNotFound", err)
+	}
+}
+
 func TestDownloadOBSResourceUsesReceiveServiceAndSID(t *testing.T) {
 	installCachedOBSToken(t)