feat(cluster): support restricted-network agent connectivity

server/internal/config/config.go

@@ -2,6 +2,8 @@ package config
 
 import (
 	"fmt"
+	"net"
+	"net/url"
 	"strings"
 	"time"
 
@@ -21,6 +23,9 @@ type ServerConfig struct {
 	Port        int    `mapstructure:"port"`
 	Mode        string `mapstructure:"mode"`
 	ExternalURL string `mapstructure:"external_url"`
+	// TrustedProxies 限定可提供 X-Forwarded-For 等头部的反向代理地址。
+	// 默认仅信任本机代理；空列表表示不信任任何代理头。
+	TrustedProxies []string `mapstructure:"trusted_proxies"`
 	// WebRoot 指向前端构建产物目录。留空时后端会按部署惯例自动探测
 	// （./web、./web/dist、/opt/backupx/web 等）。探测命中后后端直接托管
 	// 前端 SPA，无需额外的 nginx 反向代理即可访问 Web 控制台。
@@ -91,6 +96,25 @@ func Load(configPath string) (Config, error) {
 	if cfg.Server.Mode == "" {
 		cfg.Server.Mode = "release"
 	}
+	cfg.Server.ExternalURL = strings.TrimRight(strings.TrimSpace(cfg.Server.ExternalURL), "/")
+	if cfg.Server.ExternalURL != "" {
+		externalURL, parseErr := url.Parse(cfg.Server.ExternalURL)
+		if parseErr != nil || (externalURL.Scheme != "http" && externalURL.Scheme != "https") || externalURL.Host == "" || externalURL.User != nil || externalURL.RawQuery != "" || externalURL.Fragment != "" {
+			return Config{}, fmt.Errorf("server.external_url must be an absolute http(s) URL without credentials, query or fragment")
+		}
+	}
+	if len(cfg.Server.TrustedProxies) == 1 && strings.Contains(cfg.Server.TrustedProxies[0], ",") {
+		cfg.Server.TrustedProxies = strings.Split(cfg.Server.TrustedProxies[0], ",")
+	}
+	for index := range cfg.Server.TrustedProxies {
+		proxy := strings.TrimSpace(cfg.Server.TrustedProxies[index])
+		cfg.Server.TrustedProxies[index] = proxy
+		if net.ParseIP(proxy) == nil {
+			if _, _, parseErr := net.ParseCIDR(proxy); parseErr != nil {
+				return Config{}, fmt.Errorf("server.trusted_proxies contains invalid IP or CIDR %q", proxy)
+			}
+		}
+	}
 	if cfg.Database.Path == "" {
 		cfg.Database.Path = "./data/backupx.db"
 	}
@@ -142,6 +166,7 @@ func applyDefaults(v *viper.Viper) {
 	v.SetDefault("server.port", 8340)
 	v.SetDefault("server.mode", "release")
 	v.SetDefault("server.external_url", "")
+	v.SetDefault("server.trusted_proxies", []string{"127.0.0.1", "::1"})
 	v.SetDefault("server.web_root", "")
 	v.SetDefault("database.path", "./data/backupx.db")
 	v.SetDefault("security.jwt_expire", "24h")

server/internal/config/config_test.go

@@ -21,6 +21,25 @@ func TestLoadUsesDefaultsWithoutConfigFile(t *testing.T) {
 	if cfg.Database.Path != "./data/backupx.db" {
 		t.Fatalf("expected default database path, got %s", cfg.Database.Path)
 	}
+	if len(cfg.Server.TrustedProxies) != 2 {
+		t.Fatalf("expected loopback trusted proxies, got %#v", cfg.Server.TrustedProxies)
+	}
+}
+
+func TestLoadRejectsInvalidExternalURLAndTrustedProxy(t *testing.T) {
+	tests := []string{
+		"server:\n  external_url: \"ssh://master.example.com\"\n",
+		"server:\n  trusted_proxies: [\"not-an-ip\"]\n",
+	}
+	for _, content := range tests {
+		configPath := filepath.Join(t.TempDir(), "config.yaml")
+		if err := os.WriteFile(configPath, []byte(content), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		if _, err := Load(configPath); err == nil {
+			t.Fatalf("expected invalid configuration to fail: %s", content)
+		}
+	}
 }
 
 func TestLoadReadsServerExternalURLFromFile(t *testing.T) {
@@ -52,3 +71,28 @@ func TestLoadReadsServerExternalURLFromEnv(t *testing.T) {
 		t.Fatalf("expected external URL from env, got %q", cfg.Server.ExternalURL)
 	}
 }
+
+func TestLoadReadsTrustedProxiesFromEnv(t *testing.T) {
+	t.Setenv("BACKUPX_SERVER_TRUSTED_PROXIES", "127.0.0.1,172.18.0.0/16")
+	cfg, err := Load("")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(cfg.Server.TrustedProxies) != 2 || cfg.Server.TrustedProxies[1] != "172.18.0.0/16" {
+		t.Fatalf("trusted proxies = %#v", cfg.Server.TrustedProxies)
+	}
+}
+
+func TestLoadAllowsTrustedProxiesToBeDisabled(t *testing.T) {
+	configPath := filepath.Join(t.TempDir(), "config.yaml")
+	if err := os.WriteFile(configPath, []byte("server:\n  trusted_proxies: []\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	cfg, err := Load(configPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(cfg.Server.TrustedProxies) != 0 {
+		t.Fatalf("trusted proxies should be disabled, got %#v", cfg.Server.TrustedProxies)
+	}
+}