oauth2 with remote Gitea - Fix #8093 (#8149)

vendor/github.com/markbates/goth/gothic/gothic.go

@@ -245,19 +245,6 @@ var GetProviderName = getProviderName
 
 func getProviderName(req *http.Request) (string, error) {
 
-	// get all the used providers
-	providers := goth.GetProviders()
-
-	// loop over the used providers, if we already have a valid session for any provider (ie. user is already logged-in with a provider), then return that provider name
-	for _, provider := range providers {
-		p := provider.Name()
-		session, _ := Store.Get(req, p+SessionName)
-		value := session.Values[p]
-		if _, ok := value.(string); ok {
-			return p, nil
-		}
-	}
-
 	// try to get it from the url param "provider"
 	if p := req.URL.Query().Get("provider"); p != "" {
 		return p, nil
@@ -278,6 +265,17 @@ func getProviderName(req *http.Request) (string, error) {
 		return p, nil
 	}
 
+	// As a fallback, loop over the used providers, if we already have a valid session for any provider (ie. user has already begun authentication with a provider), then return that provider name
+	providers := goth.GetProviders()
+	session, _ := Store.Get(req, SessionName)
+	for _, provider := range providers {
+		p := provider.Name()
+		value := session.Values[p]
+		if _, ok := value.(string); ok {
+			return p, nil
+		}
+	}
+
 	// if not found then return an empty string with the corresponding error
 	return "", errors.New("you must select a provider")
 }