Support webSSH Origin Allowlist

backend/internal/config/origins.go

@@ -0,0 +1,136 @@
+package config
+
+import (
+	"fmt"
+	"net"
+	"net/url"
+	"strings"
+)
+
+// NormalizeAllowedOrigin accepts a browser Origin value such as
+// https://www.example.com and returns a canonical form for exact matching.
+func NormalizeAllowedOrigin(value string) (string, error) {
+	value = strings.TrimSpace(value)
+	if value == "" {
+		return "", nil
+	}
+	u, err := url.Parse(value)
+	if err != nil || u.Scheme == "" || u.Host == "" {
+		return "", fmt.Errorf("Origin must include scheme and host: %s", value)
+	}
+	scheme := strings.ToLower(u.Scheme)
+	if scheme != "http" && scheme != "https" {
+		return "", fmt.Errorf("Origin scheme must be http or https: %s", value)
+	}
+	if (u.Path != "" && u.Path != "/") || u.RawQuery != "" || u.Fragment != "" {
+		return "", fmt.Errorf("Origin must not include path, query, or fragment: %s", value)
+	}
+	host := normalizeOriginHostPort(u.Host, scheme)
+	if host == "" {
+		return "", fmt.Errorf("Origin host is required: %s", value)
+	}
+	return scheme + "://" + host, nil
+}
+
+func NormalizeAllowedOrigins(values []string) ([]string, error) {
+	result := make([]string, 0, len(values))
+	seen := map[string]bool{}
+	for _, value := range values {
+		origin, err := NormalizeAllowedOrigin(value)
+		if err != nil {
+			return nil, err
+		}
+		if origin == "" || seen[origin] {
+			continue
+		}
+		seen[origin] = true
+		result = append(result, origin)
+	}
+	return result, nil
+}
+
+func IsOriginAllowed(origin string, requestHost string) bool {
+	origin = strings.TrimSpace(origin)
+	if origin == "" {
+		return true
+	}
+	if isSameRequestOrigin(origin, requestHost) {
+		return true
+	}
+	normalized, err := NormalizeAllowedOrigin(origin)
+	if err != nil {
+		return false
+	}
+	if AppConfig == nil {
+		return false
+	}
+	for _, allowed := range AppConfig.WebSSHAllowedOrigins {
+		allowed, err := NormalizeAllowedOrigin(allowed)
+		if err == nil && normalized == allowed {
+			return true
+		}
+	}
+	return false
+}
+
+func isSameRequestOrigin(origin string, requestHost string) bool {
+	u, err := url.Parse(origin)
+	if err != nil || u.Host == "" {
+		return false
+	}
+	originHost := normalizeHostOnly(u.Hostname())
+	host := normalizeHostOnly(requestHost)
+	if originHost == "" || host == "" {
+		return false
+	}
+	if originHost == host {
+		return true
+	}
+	return isLoopbackHost(originHost) && isLoopbackHost(host)
+}
+
+func normalizeOriginHostPort(raw string, scheme string) string {
+	host := raw
+	port := ""
+	if h, p, err := net.SplitHostPort(raw); err == nil {
+		host = h
+		port = p
+	}
+	host = normalizeHostOnly(host)
+	if host == "" {
+		return ""
+	}
+	if (scheme == "https" && port == "443") || (scheme == "http" && port == "80") {
+		port = ""
+	}
+	if port != "" {
+		return net.JoinHostPort(host, port)
+	}
+	if strings.Contains(host, ":") && net.ParseIP(host) != nil {
+		return "[" + host + "]"
+	}
+	return host
+}
+
+func normalizeHostOnly(raw string) string {
+	raw = strings.TrimSpace(raw)
+	if raw == "" {
+		return ""
+	}
+	if h, _, err := net.SplitHostPort(raw); err == nil {
+		raw = h
+	}
+	raw = strings.Trim(raw, "[]")
+	if ip := net.ParseIP(raw); ip != nil {
+		return strings.ToLower(ip.String())
+	}
+	return strings.TrimSuffix(strings.ToLower(raw), ".")
+}
+
+func isLoopbackHost(host string) bool {
+	if host == "localhost" {
+		return true
+	}
+	ip := net.ParseIP(host)
+	return ip != nil && ip.IsLoopback()
+}