Sanitize post for audit with preview links (#23745)

* sanitize post for audit with preview links

* add unit test

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/post.go

@@ -120,6 +120,11 @@ type Post struct {
 }
 
 func (o *Post) Auditable() map[string]interface{} {
+	var metaData map[string]any
+	if o.Metadata != nil {
+		metaData = o.Metadata.Auditable()
+	}
+
 	return map[string]interface{}{
 		"id":              o.Id,
 		"create_at":       o.CreateAt,
@@ -139,7 +144,7 @@ func (o *Post) Auditable() map[string]interface{} {
 		"reply_count":     o.ReplyCount,
 		"last_reply_at":   o.LastReplyAt,
 		"is_following":    o.IsFollowing,
-		"metadata":        o.Metadata,
+		"metadata":        metaData,
 	}
 }
 

server/public/model/post_embed.go

@@ -23,3 +23,11 @@ type PostEmbed struct {
 	// Any additional data for the embedded content. Only used for OpenGraph embeds.
 	Data any `json:"data,omitempty"`
 }
+
+func (pe *PostEmbed) Auditable() map[string]any {
+	// filter out embedded content.
+	return map[string]any{
+		"type": pe.Type,
+		"url":  pe.URL,
+	}
+}

server/public/model/post_metadata.go

@@ -30,6 +30,26 @@ type PostMetadata struct {
 	Acknowledgements []*PostAcknowledgement `json:"acknowledgements,omitempty"`
 }
 
+func (pm *PostMetadata) Auditable() map[string]any {
+	embeds := make([]map[string]any, 0, len(pm.Embeds))
+	for _, pe := range pm.Embeds {
+		embeds = append(embeds, pe.Auditable())
+	}
+	if len(embeds) == 0 {
+		embeds = nil
+	}
+
+	return map[string]any{
+		"embeds":           embeds,
+		"emojis":           pm.Emojis,
+		"files":            pm.Files,
+		"images":           pm.Images,
+		"reactions":        pm.Reactions,
+		"priority":         pm.Priority,
+		"acknowledgements": pm.Acknowledgements,
+	}
+}
+
 type PostImage struct {
 	Width  int `json:"width"`
 	Height int `json:"height"`