MM-45208: strip post meta for plugins (#20686)

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* Revert "Revert "Removed the opengraph type dependency for plugins by stripping post Metadata (#20612)" (#20684)"

This reverts commit 32dee6d449.

* Fixed race condition

* PR feedback

* lint

app/plugin_api.go

@@ -513,7 +513,7 @@ func (api *PluginAPI) SearchPostsInTeam(teamID string, paramsList []*model.Searc
 	if err != nil {
 		return nil, err
 	}
-	return postList.ToSlice(), nil
+	return postList.ForPlugin().ToSlice(), nil
 }
 
 func (api *PluginAPI) SearchPostsInTeamForUser(teamID string, userID string, searchParams model.SearchParameter) (*model.PostSearchResults, *model.AppError) {
@@ -547,7 +547,11 @@ func (api *PluginAPI) SearchPostsInTeamForUser(teamID string, userID string, sea
 		includeDeletedChannels = *searchParams.IncludeDeletedChannels
 	}
 
-	return api.app.SearchPostsForUser(api.ctx, terms, userID, teamID, isOrSearch, includeDeletedChannels, timeZoneOffset, page, perPage, model.ModifierMessages)
+	results, appErr := api.app.SearchPostsForUser(api.ctx, terms, userID, teamID, isOrSearch, includeDeletedChannels, timeZoneOffset, page, perPage, model.ModifierMessages)
+	if results != nil {
+		results = results.ForPlugin()
+	}
+	return results, appErr
 }
 
 func (api *PluginAPI) AddChannelMember(channelID, userID string) (*model.ChannelMember, *model.AppError) {
@@ -627,7 +631,11 @@ func (api *PluginAPI) GetGroupsForUser(userID string) ([]*model.Group, *model.Ap
 }
 
 func (api *PluginAPI) CreatePost(post *model.Post) (*model.Post, *model.AppError) {
-	return api.app.CreatePostMissingChannel(api.ctx, post, true)
+	post, appErr := api.app.CreatePostMissingChannel(api.ctx, post, true)
+	if post != nil {
+		post = post.ForPlugin()
+	}
+	return post, appErr
 }
 
 func (api *PluginAPI) AddReaction(reaction *model.Reaction) (*model.Reaction, *model.AppError) {
@@ -643,11 +651,11 @@ func (api *PluginAPI) GetReactions(postID string) ([]*model.Reaction, *model.App
 }
 
 func (api *PluginAPI) SendEphemeralPost(userID string, post *model.Post) *model.Post {
-	return api.app.SendEphemeralPost(api.ctx, userID, post)
+	return api.app.SendEphemeralPost(api.ctx, userID, post).ForPlugin()
 }
 
 func (api *PluginAPI) UpdateEphemeralPost(userID string, post *model.Post) *model.Post {
-	return api.app.UpdateEphemeralPost(api.ctx, userID, post)
+	return api.app.UpdateEphemeralPost(api.ctx, userID, post).ForPlugin()
 }
 
 func (api *PluginAPI) DeleteEphemeralPost(userID, postID string) {
@@ -660,31 +668,59 @@ func (api *PluginAPI) DeletePost(postID string) *model.AppError {
 }
 
 func (api *PluginAPI) GetPostThread(postID string) (*model.PostList, *model.AppError) {
-	return api.app.GetPostThread(postID, model.GetPostsOptions{}, "")
+	list, appErr := api.app.GetPostThread(postID, model.GetPostsOptions{}, "")
+	if list != nil {
+		list = list.ForPlugin()
+	}
+	return list, appErr
 }
 
 func (api *PluginAPI) GetPost(postID string) (*model.Post, *model.AppError) {
-	return api.app.GetSinglePost(postID, false)
+	post, appErr := api.app.GetSinglePost(postID, false)
+	if post != nil {
+		post = post.ForPlugin()
+	}
+	return post, appErr
 }
 
 func (api *PluginAPI) GetPostsSince(channelID string, time int64) (*model.PostList, *model.AppError) {
-	return api.app.GetPostsSince(model.GetPostsSinceOptions{ChannelId: channelID, Time: time})
+	list, appErr := api.app.GetPostsSince(model.GetPostsSinceOptions{ChannelId: channelID, Time: time})
+	if list != nil {
+		list = list.ForPlugin()
+	}
+	return list, appErr
 }
 
 func (api *PluginAPI) GetPostsAfter(channelID, postID string, page, perPage int) (*model.PostList, *model.AppError) {
-	return api.app.GetPostsAfterPost(model.GetPostsOptions{ChannelId: channelID, PostId: postID, Page: page, PerPage: perPage})
+	list, appErr := api.app.GetPostsAfterPost(model.GetPostsOptions{ChannelId: channelID, PostId: postID, Page: page, PerPage: perPage})
+	if list != nil {
+		list = list.ForPlugin()
+	}
+	return list, appErr
 }
 
 func (api *PluginAPI) GetPostsBefore(channelID, postID string, page, perPage int) (*model.PostList, *model.AppError) {
-	return api.app.GetPostsBeforePost(model.GetPostsOptions{ChannelId: channelID, PostId: postID, Page: page, PerPage: perPage})
+	list, appErr := api.app.GetPostsBeforePost(model.GetPostsOptions{ChannelId: channelID, PostId: postID, Page: page, PerPage: perPage})
+	if list != nil {
+		list = list.ForPlugin()
+	}
+	return list, appErr
 }
 
 func (api *PluginAPI) GetPostsForChannel(channelID string, page, perPage int) (*model.PostList, *model.AppError) {
-	return api.app.GetPostsPage(model.GetPostsOptions{ChannelId: channelID, Page: page, PerPage: perPage})
+	list, appErr := api.app.GetPostsPage(model.GetPostsOptions{ChannelId: channelID, Page: page, PerPage: perPage})
+	if list != nil {
+		list = list.ForPlugin()
+	}
+	return list, appErr
 }
 
 func (api *PluginAPI) UpdatePost(post *model.Post) (*model.Post, *model.AppError) {
-	return api.app.UpdatePost(api.ctx, post, false)
+	post, appErr := api.app.UpdatePost(api.ctx, post, false)
+	if post != nil {
+		post = post.ForPlugin()
+	}
+	return post, appErr
 }
 
 func (api *PluginAPI) GetProfileImage(userID string) ([]byte, *model.AppError) {

app/post.go

@@ -259,7 +259,7 @@ func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel
 		var rejectionError *model.AppError
 		pluginContext := pluginContext(c)
 		pluginsEnvironment.RunMultiPluginHook(func(hooks plugin.Hooks) bool {
-			replacementPost, rejectionReason := hooks.MessageWillBePosted(pluginContext, post)
+			replacementPost, rejectionReason := hooks.MessageWillBePosted(pluginContext, post.ForPlugin())
 			if rejectionReason != "" {
 				id := "Post rejected by plugin. " + rejectionReason
 				if rejectionReason == plugin.DismissPostError {
@@ -269,6 +269,7 @@ func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel
 				return false
 			}
 			if replacementPost != nil {
+				// the original post's metadata (if there ever was any) is lost, and will be rebuilt.
 				post = replacementPost
 			}
 
@@ -309,21 +310,14 @@ func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel
 	// might be duplicating requests.
 	a.Srv().seenPendingPostIdsCache.SetWithExpiry(post.PendingPostId, rpost.Id, PendingPostIDsCacheTTL)
 
-	// We make a copy of the post for the plugin hook to avoid a race condition.
+	// We make a copy of the post for the plugin hook to avoid a race condition,
-	rPostCopy := rpost.Clone()
+	// and to remove the non-GOB-encodable Metadata from it.
-
-	// FIXME: Removes PreviewPost from the post payload sent to the MessageHasBeenPosted hook so that plugins compiled with older versions of
-	// Mattermost—without the gob registration of the PreviewPost struct—won't crash.
-	if rPostCopy.Metadata != nil {
-		rPostCopy.Metadata = rPostCopy.Metadata.Copy()
-	}
-	rPostCopy.RemovePreviewPost()
-
 	if pluginsEnvironment := a.GetPluginsEnvironment(); pluginsEnvironment != nil {
+		pluginPost := rpost.ForPlugin()
 		a.Srv().Go(func() {
 			pluginContext := pluginContext(c)
 			pluginsEnvironment.RunMultiPluginHook(func(hooks plugin.Hooks) bool {
-				hooks.MessageHasBeenPosted(pluginContext, rPostCopy)
+				hooks.MessageHasBeenPosted(pluginContext, pluginPost)
 				return true
 			}, plugin.MessageHasBeenPostedID)
 		})
@@ -650,12 +644,15 @@ func (a *App) UpdatePost(c *request.Context, post *model.Post, safeUpdate bool)
 		var rejectionReason string
 		pluginContext := pluginContext(c)
 		pluginsEnvironment.RunMultiPluginHook(func(hooks plugin.Hooks) bool {
-			newPost, rejectionReason = hooks.MessageWillBeUpdated(pluginContext, newPost, oldPost)
+			newPost, rejectionReason = hooks.MessageWillBeUpdated(pluginContext, newPost.ForPlugin(), oldPost.ForPlugin())
 			return post != nil
 		}, plugin.MessageWillBeUpdatedID)
 		if newPost == nil {
 			return nil, model.NewAppError("UpdatePost", "Post rejected by plugin. "+rejectionReason, nil, "", http.StatusBadRequest)
 		}
+		// Restore the post metadata that was stripped by the plugin. Set it to
+		// the last known good.
+		newPost.Metadata = oldPost.Metadata
 	}
 
 	rpost, nErr := a.Srv().Store.Post().Update(newPost, oldPost)
@@ -670,10 +667,12 @@ func (a *App) UpdatePost(c *request.Context, post *model.Post, safeUpdate bool)
 	}
 
 	if pluginsEnvironment := a.GetPluginsEnvironment(); pluginsEnvironment != nil {
+		pluginOldPost := oldPost.ForPlugin()
+		pluginNewPost := newPost.ForPlugin()
 		a.Srv().Go(func() {
 			pluginContext := pluginContext(c)
 			pluginsEnvironment.RunMultiPluginHook(func(hooks plugin.Hooks) bool {
-				hooks.MessageHasBeenUpdated(pluginContext, newPost, oldPost)
+				hooks.MessageHasBeenUpdated(pluginContext, pluginNewPost, pluginOldPost)
 				return true
 			}, plugin.MessageHasBeenUpdatedID)
 		})

model/post.go

@@ -736,18 +736,10 @@ func (o *Post) ToNilIfInvalid() *Post {
 	return o
 }
 
-func (o *Post) RemovePreviewPost() {
+func (o *Post) ForPlugin() *Post {
-	if o.Metadata == nil || o.Metadata.Embeds == nil {
+	p := o.Clone()
-		return
+	p.Metadata = nil
-	}
+	return p
-	n := 0
-	for _, embed := range o.Metadata.Embeds {
-		if embed.Type != PostEmbedPermalink {
-			o.Metadata.Embeds[n] = embed
-			n++
-		}
-	}
-	o.Metadata.Embeds = o.Metadata.Embeds[:n]
 }
 
 func (o *Post) GetPreviewPost() *PreviewPost {

model/post_list.go

@@ -46,6 +46,14 @@ func (o *PostList) Clone() *PostList {
 	}
 }
 
+func (o *PostList) ForPlugin() *PostList {
+	copy := o.Clone()
+	for k, p := range copy.Posts {
+		copy.Posts[k] = p.ForPlugin()
+	}
+	return copy
+}
+
 func (o *PostList) ToSlice() []*Post {
 	var posts []*Post
 

model/post_search_results.go

@@ -33,3 +33,9 @@ func (o *PostSearchResults) EncodeJSON(w io.Writer) error {
 	o.PostList.StripActionIntegrations()
 	return json.NewEncoder(w).Encode(o)
 }
+
+func (o *PostSearchResults) ForPlugin() *PostSearchResults {
+	copy := *o
+	copy.PostList = copy.PostList.ForPlugin()
+	return &copy
+}

plugin/client_rpc.go

@@ -21,7 +21,6 @@ import (
 	"reflect"
 	"sync"
 
-	"github.com/dyatlov/go-opengraph/opengraph"
 	"github.com/go-sql-driver/mysql"
 	"github.com/hashicorp/go-plugin"
 	"github.com/lib/pq"
@@ -164,7 +163,6 @@ func init() {
 	gob.Register(&pq.Error{})
 	gob.Register(&mysql.MySQLError{})
 	gob.Register(&ErrorString{})
-	gob.Register(&opengraph.OpenGraph{})
 	gob.Register(&model.AutocompleteDynamicListArg{})
 	gob.Register(&model.AutocompleteStaticListArg{})
 	gob.Register(&model.AutocompleteTextArg{})