platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-api/app/resolver/dns_helpers.go

@@ -0,0 +1,52 @@
+package resolver
+
+import (
+	"errors"
+	"net"
+	"strings"
+)
+
+func ClassifyDNSError(err error) string {
+	if err == nil {
+		return "other"
+	}
+	var dnsErr *net.DNSError
+	if errors.As(err, &dnsErr) {
+		if dnsErr.IsNotFound {
+			return "nxdomain"
+		}
+		if dnsErr.IsTimeout {
+			return "timeout"
+		}
+		if dnsErr.IsTemporary {
+			return "temporary"
+		}
+	}
+	msg := strings.ToLower(err.Error())
+	switch {
+	case strings.Contains(msg, "no such host"), strings.Contains(msg, "nxdomain"):
+		return "nxdomain"
+	case strings.Contains(msg, "i/o timeout"), strings.Contains(msg, "timeout"):
+		return "timeout"
+	case strings.Contains(msg, "temporary"):
+		return "temporary"
+	default:
+		return "other"
+	}
+}
+
+func SplitDNS(dns string) (string, string) {
+	if strings.Contains(dns, "#") {
+		parts := strings.SplitN(dns, "#", 2)
+		host := strings.TrimSpace(parts[0])
+		port := strings.TrimSpace(parts[1])
+		if host == "" {
+			host = "127.0.0.1"
+		}
+		if port == "" {
+			port = "53"
+		}
+		return host, port
+	}
+	return strings.TrimSpace(dns), ""
+}