Improve self checks when adding a new channel member (#33404) (#33925)

Automatic Merge

server/channels/api4/channel.go

@@ -1972,16 +1972,15 @@ func addChannelMember(c *Context, w http.ResponseWriter, r *http.Request) {
 				lastError = err
 				continue
 			}
-		} else {
-			// user is already a member, go to next
-			c.Logger.Warn("User is already a channel member, skipping", mlog.String("UserId", userId), mlog.String("ChannelId", channel.Id))
-			newChannelMembers = append(newChannelMembers, *existingMember)
-			continue
 		}
 
 		if channel.Type == model.ChannelTypeOpen {
 			isSelfAdd := member.UserId == c.AppContext.Session().UserId
-			if isSelfAdd && !canAddSelf {
+			if isSelfAdd && existingMember != nil {
+				// users should be able to add themselves if they're already a member, even if they don't have permissions
+				newChannelMembers = append(newChannelMembers, *existingMember)
+				continue
+			} else if isSelfAdd && !canAddSelf {
 				c.Logger.Warn("Error adding channel member, Invalid Permission to add self", mlog.String("UserId", userId), mlog.String("ChannelId", channel.Id))
 				c.SetPermissionError(model.PermissionJoinPublicChannels)
 				lastError = c.Err
@@ -1994,6 +1993,13 @@ func addChannelMember(c *Context, w http.ResponseWriter, r *http.Request) {
 			}
 		}
 
+		if existingMember != nil {
+			// user is already a member, go to next
+			c.Logger.Warn("User is already a channel member, skipping", mlog.String("UserId", userId), mlog.String("ChannelId", channel.Id))
+			newChannelMembers = append(newChannelMembers, *existingMember)
+			continue
+		}
+
 		cm, err := c.App.AddChannelMember(c.AppContext, member.UserId, channel, app.ChannelMemberOpts{
 			UserRequestorID: c.AppContext.Session().UserId,
 			PostRootID:      postRootId,