[GITEA] add option for banning dots in usernames

Refs: https://codeberg.org/forgejo/forgejo/pulls/676

Author:    Panagiotis "Ivory" Vasilopoulos <git@n0toose.net>
Date:      Mon Jun 12 13:57:01 2023 +0200

Co-authored-by: Gusted <postmaster@gusted.xyz>
(cherry picked from commit fabdda5c6e)
(cherry picked from commit d2c7f45621)
(cherry picked from commit dfdbaba3d6)
(cherry picked from commit a3cda092b8)
(cherry picked from commit f0fdb5905c)
(cherry picked from commit 9697e48c1f)
(cherry picked from commit 46e31009a8)
(cherry picked from commit 5bb2c54b6f)

modules/validation/helpers.go

@@ -92,13 +92,20 @@ func IsValidExternalTrackerURLFormat(uri string) bool {
 }
 
 var (
-	validUsernamePattern   = regexp.MustCompile(`^[\da-zA-Z][-.\w]*$`)
-	invalidUsernamePattern = regexp.MustCompile(`[-._]{2,}|[-._]$`) // No consecutive or trailing non-alphanumeric chars
+	validUsernamePatternWithDots    = regexp.MustCompile(`^[\da-zA-Z][-.\w]*$`)
+	validUsernamePatternWithoutDots = regexp.MustCompile(`^[\da-zA-Z][-\w]*$`)
+
+	// No consecutive or trailing non-alphanumeric chars, catches both cases
+	invalidUsernamePattern = regexp.MustCompile(`[-._]{2,}|[-._]$`)
 )
 
 // IsValidUsername checks if username is valid
 func IsValidUsername(name string) bool {
 	// It is difficult to find a single pattern that is both readable and effective,
 	// but it's easier to use positive and negative checks.
-	return validUsernamePattern.MatchString(name) && !invalidUsernamePattern.MatchString(name)
+	if setting.Service.AllowDotsInUsernames {
+		return validUsernamePatternWithDots.MatchString(name) && !invalidUsernamePattern.MatchString(name)
+	}
+
+	return validUsernamePatternWithoutDots.MatchString(name) && !invalidUsernamePattern.MatchString(name)
 }

modules/validation/helpers_test.go

@@ -155,7 +155,8 @@ func Test_IsValidExternalTrackerURLFormat(t *testing.T) {
 	}
 }
 
-func TestIsValidUsername(t *testing.T) {
+func TestIsValidUsernameAllowDots(t *testing.T) {
+	setting.Service.AllowDotsInUsernames = true
 	tests := []struct {
 		arg  string
 		want bool
@@ -185,3 +186,31 @@ func TestIsValidUsername(t *testing.T) {
 		})
 	}
 }
+
+func TestIsValidUsernameBanDots(t *testing.T) {
+	setting.Service.AllowDotsInUsernames = false
+	defer func() {
+		setting.Service.AllowDotsInUsernames = true
+	}()
+
+	tests := []struct {
+		arg  string
+		want bool
+	}{
+		{arg: "a", want: true},
+		{arg: "abc", want: true},
+		{arg: "0.b-c", want: false},
+		{arg: "a.b-c_d", want: false},
+		{arg: ".abc", want: false},
+		{arg: "abc.", want: false},
+		{arg: "a..bc", want: false},
+		{arg: "a...bc", want: false},
+		{arg: "a.-bc", want: false},
+		{arg: "a._bc", want: false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.arg, func(t *testing.T) {
+			assert.Equalf(t, tt.want, IsValidUsername(tt.arg), "IsValidUsername[AllowDotsInUsernames=false](%v)", tt.arg)
+		})
+	}
+}