Return nicer error if trying to pull from non-existent user

Gitea serv will currently return an 500 if we try to pull from a repository where
the owner does not exist.

This PR checks for the UserNotExist Error when checking for the user and will
return a NotFound error instead.

Fix go-gitea#18225

Signed-off-by: Andrew Thornton <[email protected]>

Author: zeripath

routers/private/serv.go

@@ -111,8 +111,17 @@ func ServCommand(ctx *context.PrivateContext) {
 
 	owner, err := user_model.GetUserByName(results.OwnerName)
 	if err != nil {
+		if user_model.IsErrUserNotExist(err) {
+			// User is fetching/cloning a non-existent repository
+			log.Error("Failed authentication attempt (cannot find repository: %s/%s) from %s", results.OwnerName, results.RepoName, ctx.RemoteAddr())
+			ctx.JSON(http.StatusNotFound, private.ErrServCommand{
+				Results: results,
+				Err:     fmt.Sprintf("Cannot find repository: %s/%s", results.OwnerName, results.RepoName),
+			})
+			return
+		}
 		log.Error("Unable to get repository owner: %s/%s Error: %v", results.OwnerName, results.RepoName, err)
-		ctx.JSON(http.StatusInternalServerError, private.ErrServCommand{
+		ctx.JSON(http.StatusForbidden, private.ErrServCommand{
 			Results: results,
 			Err:     fmt.Sprintf("Unable to get repository owner: %s/%s %v", results.OwnerName, results.RepoName, err),
 		})