feat(upload): integrate upload service for chat image validation and S3 uploads

- Added UploadService to handle image uploads and validation for chat messages.
- Updated ChatService and MessageService to utilize UploadService for validating image segments in messages.
- Enhanced wire generation to inject UploadService into relevant services.
- Introduced UploadImageBytes method in UploadService for uploading images directly from memory.
- Added TrustedPublicURLPrefix method in S3 Client for generating public URLs for uploaded images.

internal/service/chat_service.go

@@ -64,6 +64,7 @@ type chatServiceImpl struct {
 
 	// 缓存相关字段
 	conversationCache *cache.ConversationCache
+	uploadService     *UploadService // 校验聊天图片 URL 来源
 }
 
 // NewChatService 创建聊天服务
@@ -74,6 +75,7 @@ func NewChatService(
 	sensitive SensitiveService,
 	sseHub *sse.Hub,
 	cacheBackend cache.Cache,
+	uploadService *UploadService,
 ) ChatService {
 	// 创建适配器
 	convRepoAdapter := cache.NewConversationRepositoryAdapter(repo)
@@ -94,6 +96,7 @@ func NewChatService(
 		sensitive:         sensitive,
 		sseHub:            sseHub,
 		conversationCache: conversationCache,
+		uploadService:     uploadService,
 	}
 }
 
@@ -269,7 +272,7 @@ func (s *chatServiceImpl) SendMessage(ctx context.Context, senderID string, conv
 	}
 
 	// 验证用户是否是会话参与者
-	participant, err := s.getParticipant(ctx, conversationID, senderID)
+	_, err = s.getParticipant(ctx, conversationID, senderID)
 	if err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
 			return nil, errors.New("您不是该会话的参与者")
@@ -277,6 +280,12 @@ func (s *chatServiceImpl) SendMessage(ctx context.Context, senderID string, conv
 		return nil, fmt.Errorf("failed to get participant: %w", err)
 	}
 
+	if s.uploadService != nil {
+		if err := s.uploadService.ValidateChatMessageImageSegments(segments); err != nil {
+			return nil, err
+		}
+	}
+
 	// 创建消息
 	message := &model.Message{
 		ConversationID: conversationID,
@@ -351,8 +360,6 @@ func (s *chatServiceImpl) SendMessage(ctx context.Context, senderID string, conv
 		}
 	}
 
-	_ = participant // 避免未使用变量警告
-
 	return message, nil
 }
 
@@ -701,6 +708,12 @@ func (s *chatServiceImpl) SaveMessage(ctx context.Context, senderID string, conv
 		return nil, fmt.Errorf("failed to get participant: %w", err)
 	}
 
+	if s.uploadService != nil {
+		if err := s.uploadService.ValidateChatMessageImageSegments(segments); err != nil {
+			return nil, err
+		}
+	}
+
 	message := &model.Message{
 		ConversationID: conversationID,
 		SenderID:       senderID,

internal/service/message_segment_image.go

@@ -0,0 +1,66 @@
+package service
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+
+	"carrot_bbs/internal/model"
+)
+
+// ValidateChatMessageImageSegments 校验聊天消息中的图片段：禁止 data:/base64 内联，仅允许引用本站 S3 公开前缀下的 URL。
+func (s *UploadService) ValidateChatMessageImageSegments(segments model.MessageSegments) error {
+	if s == nil || s.s3Client == nil {
+		return nil
+	}
+	prefix := strings.TrimSpace(s.s3Client.TrustedPublicURLPrefix())
+	if prefix == "" {
+		return nil
+	}
+
+	for _, seg := range segments {
+		if seg.Type != string(model.ContentTypeImage) && seg.Type != "image" {
+			continue
+		}
+		if seg.Data == nil {
+			return fmt.Errorf("图片消息数据无效")
+		}
+		urlStr, _ := seg.Data["url"].(string)
+		urlStr = strings.TrimSpace(urlStr)
+		if urlStr == "" {
+			return fmt.Errorf("图片消息缺少 url")
+		}
+		low := strings.ToLower(urlStr)
+		if strings.HasPrefix(low, "data:") || strings.HasPrefix(low, "base64:") || strings.HasPrefix(low, "base64://") {
+			return fmt.Errorf("禁止在消息中内联 base64 或 data URL，请先通过上传接口获取图片地址")
+		}
+		if strings.ContainsAny(urlStr, "\n\r\x00") {
+			return fmt.Errorf("非法图片地址")
+		}
+
+		u, err := url.Parse(urlStr)
+		if err != nil || (u.Scheme != "http" && u.Scheme != "https") {
+			return fmt.Errorf("图片地址必须为 http(s) 链接")
+		}
+		if u.Host == "" {
+			return fmt.Errorf("图片地址无效")
+		}
+
+		if !strings.HasPrefix(urlStr, prefix) {
+			return fmt.Errorf("图片必须使用本站上传接口生成的资源地址")
+		}
+
+		if thumb, ok := seg.Data["thumbnail_url"].(string); ok {
+			thumb = strings.TrimSpace(thumb)
+			if thumb != "" {
+				if strings.HasPrefix(strings.ToLower(thumb), "data:") {
+					return fmt.Errorf("禁止在图片消息中使用 data URL 缩略图")
+				}
+				if !strings.HasPrefix(thumb, prefix) {
+					return fmt.Errorf("缩略图地址不合法")
+				}
+			}
+		}
+	}
+	return nil
+}

internal/service/message_service.go

@@ -35,10 +35,12 @@ type MessageService struct {
 
 	// 基础缓存（用于简单缓存操作）
 	baseCache cache.Cache
+
+	uploadService *UploadService
 }
 
 // NewMessageService 创建消息服务
-func NewMessageService(db *gorm.DB, messageRepo *repository.MessageRepository, cacheBackend cache.Cache) *MessageService {
+func NewMessageService(db *gorm.DB, messageRepo *repository.MessageRepository, cacheBackend cache.Cache, uploadService *UploadService) *MessageService {
 	// 创建适配器
 	convRepoAdapter := cache.NewConversationRepositoryAdapter(messageRepo)
 	msgRepoAdapter := cache.NewMessageRepositoryAdapter(messageRepo)
@@ -56,6 +58,7 @@ func NewMessageService(db *gorm.DB, messageRepo *repository.MessageRepository, c
 		messageRepo:       messageRepo,
 		conversationCache: conversationCache,
 		baseCache:         cacheBackend,
+		uploadService:     uploadService,
 	}
 }
 
@@ -74,6 +77,12 @@ func (s *MessageService) SendMessage(ctx context.Context, senderID, receiverID s
 		return nil, err
 	}
 
+	if s.uploadService != nil {
+		if err := s.uploadService.ValidateChatMessageImageSegments(segments); err != nil {
+			return nil, err
+		}
+	}
+
 	msg := &model.Message{
 		ConversationID: conv.ID,
 		SenderID:       senderID,

internal/service/upload_service.go

@@ -75,6 +75,41 @@ func (s *UploadService) UploadImage(ctx context.Context, file *multipart.FileHea
 	return url, previewURL, previewURLLarge, nil
 }
 
+const maxUploadImageBytesFromBuffer = 15 << 20 // 与聊天内联解码上限一致，略大于 upload.max_file_size 时可接受
+
+// UploadImageBytes 从内存字节上传图片（与 multipart 上传走同一套压缩与存储逻辑）。
+func (s *UploadService) UploadImageBytes(ctx context.Context, raw []byte, filename string) (url, previewURL, previewURLLarge string, err error) {
+	if len(raw) == 0 {
+		return "", "", "", fmt.Errorf("empty image data")
+	}
+	if len(raw) > maxUploadImageBytesFromBuffer {
+		return "", "", "", fmt.Errorf("image data too large")
+	}
+
+	detectedType := normalizeImageContentType(http.DetectContentType(raw))
+	compressedData, compressedType, cerr := compressImageData(raw, detectedType)
+	if cerr != nil {
+		compressedData = raw
+		compressedType = detectedType
+	}
+	compressedType = cmp.Or(compressedType, http.DetectContentType(compressedData))
+	ext := cmp.Or(getExtFromContentType(compressedType), strings.ToLower(filepath.Ext(filename)), ".jpg")
+
+	hash := sha256.Sum256(compressedData)
+	hashStr := fmt.Sprintf("%x", hash)
+	objectName := fmt.Sprintf("images/%s%s", hashStr, ext)
+	url, err = s.s3Client.UploadData(ctx, objectName, compressedData, compressedType)
+	if err != nil {
+		return "", "", "", fmt.Errorf("failed to upload to S3: %w", err)
+	}
+
+	previewURL, previewURLLarge, prevErr := s.GeneratePreviewImages(ctx, compressedData, hashStr)
+	if prevErr != nil {
+		zap.L().Warn("UploadImageBytes: preview generation failed", zap.Error(prevErr))
+	}
+	return url, previewURL, previewURLLarge, nil
+}
+
 // getExtFromContentType 根据Content-Type获取文件扩展名
 func getExtFromContentType(contentType string) string {
 	baseType, _, err := mime.ParseMediaType(contentType)