feat: Add trusted redirect domains.

common/url_validator.go

@@ -0,0 +1,39 @@
+package common
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+
+	"github.com/QuantumNous/new-api/constant"
+)
+
+// ValidateRedirectURL validates that a redirect URL is safe to use.
+// It checks that:
+//   - The URL is properly formatted
+//   - The scheme is either http or https
+//   - The domain is in the trusted domains list (exact match or subdomain)
+//
+// Returns nil if the URL is valid and trusted, otherwise returns an error
+// describing why the validation failed.
+func ValidateRedirectURL(rawURL string) error {
+	// Parse the URL
+	parsedURL, err := url.Parse(rawURL)
+	if err != nil {
+		return fmt.Errorf("invalid URL format: %s", err.Error())
+	}
+
+	if parsedURL.Scheme != "http" && parsedURL.Scheme != "https" {
+		return fmt.Errorf("invalid URL scheme: only http and https are allowed")
+	}
+
+	domain := strings.ToLower(parsedURL.Hostname())
+
+	for _, trustedDomain := range constant.TrustedRedirectDomains {
+		if domain == trustedDomain || strings.HasSuffix(domain, "."+trustedDomain) {
+			return nil
+		}
+	}
+
+	return fmt.Errorf("domain %s is not in the trusted domains list", domain)
+}