feat: add new settings option to allow external fonts

internal/validator/user.go

@@ -123,6 +123,12 @@ func ValidateUserModification(store *storage.Storage, userID int64, changes *mod
 		}
 	}
 
+	if changes.ExternalFontHosts != nil {
+		if !IsValidDomainList(*changes.ExternalFontHosts) {
+			return locale.NewLocalizedError("error.settings_invalid_domain_list")
+		}
+	}
+
 	return nil
 }
 

internal/validator/validator.go

@@ -7,8 +7,11 @@ import (
 	"fmt"
 	"net/url"
 	"regexp"
+	"strings"
 )
 
+var domainRegex = regexp.MustCompile(`^([a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$`)
+
 // ValidateRange makes sure the offset/limit values are valid.
 func ValidateRange(offset, limit int) error {
 	if offset < 0 {
@@ -43,3 +46,24 @@ func IsValidURL(absoluteURL string) bool {
 	_, err := url.ParseRequestURI(absoluteURL)
 	return err == nil
 }
+
+func IsValidDomain(domain string) bool {
+	domain = strings.ToLower(domain)
+
+	if len(domain) < 1 || len(domain) > 253 {
+		return false
+	}
+
+	return domainRegex.MatchString(domain)
+}
+
+func IsValidDomainList(value string) bool {
+	domains := strings.Split(strings.TrimSpace(value), " ")
+	for _, domain := range domains {
+		if !IsValidDomain(domain) {
+			return false
+		}
+	}
+
+	return true
+}

internal/validator/validator_test.go

@@ -59,3 +59,21 @@ func TestIsValidRegex(t *testing.T) {
 		}
 	}
 }
+
+func TestIsValidDomain(t *testing.T) {
+	scenarios := map[string]bool{
+		"example.org":          true,
+		"example":              false,
+		"example.":             false,
+		"example..":            false,
+		"mail.example.com:443": false,
+		"*.example.com":        false,
+	}
+
+	for domain, expected := range scenarios {
+		result := IsValidDomain(domain)
+		if result != expected {
+			t.Errorf(`Unexpected result, got %v instead of %v`, result, expected)
+		}
+	}
+}