feat: 添加自定义 DNS 解析器

2025-10-18 18:49:23 +08:00 · 2025-09-13 02:05:00 +08:00
parent 7af8e540db
commit 9834a55e5d
7 changed files with 175 additions and 17 deletions
--- a/dnsresolver/resolver.go
+++ b/dnsresolver/resolver.go
@@ -0,0 +1,132 @@
+package dnsresolver
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"strings"
+	"time"
+)
+
+var (
+	// DNS服务器列表，按优先级排序
+	DNSServers = []string{
+		"114.114.114.114:53", // 114DNS，中国大陆
+		"8.8.8.8:53",         // Google DNS，全球
+		"8.8.4.4:53",         // Google DNS备用，全球
+		"1.1.1.1:53",         // Cloudflare DNS，全球
+		"223.5.5.5:53",       // 阿里DNS，中国大陆
+		"119.29.29.29:53",    // DNSPod，中国大陆
+	}
+
+	// CustomDNSServer 自定义DNS服务器，可以通过命令行参数设置
+	CustomDNSServer string
+)
+
+// SetCustomDNSServer 设置自定义DNS服务器
+func SetCustomDNSServer(dnsServer string) {
+	if dnsServer != "" {
+		// 检查是否已包含端口，如果没有则添加默认端口53
+		if !strings.Contains(dnsServer, ":") {
+			dnsServer = dnsServer + ":53"
+		}
+		CustomDNSServer = dnsServer
+	}
+}
+
+// getCurrentDNSServer 获取当前要使用的DNS服务器
+func getCurrentDNSServer() string {
+	if CustomDNSServer != "" {
+		return CustomDNSServer
+	}
+	// 如果没有设置自定义DNS，返回默认的第一个
+	return DNSServers[0]
+}
+
+// GetCustomResolver 返回一个使用指定DNS服务器的解析器
+func GetCustomResolver() *net.Resolver {
+	return &net.Resolver{
+		PreferGo: true,
+		Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
+			d := net.Dialer{
+				Timeout: 10 * time.Second,
+			}
+
+			// 尝试自定义DNS或默认DNS
+			dnsServer := getCurrentDNSServer()
+			conn, err := d.DialContext(ctx, "udp", dnsServer)
+			if err == nil {
+				return conn, nil
+			}
+
+			// 如果连接失败，尝试其他DNS服务器
+			for _, server := range DNSServers {
+				if server != dnsServer { // 避免重复尝试
+					conn, err := d.DialContext(ctx, "udp", server)
+					if err == nil {
+						return conn, nil
+					}
+				}
+			}
+
+			// 所有DNS服务器都失败，返回最后一次的错误
+			return nil, err
+		},
+	}
+}
+
+// GetHTTPClient 返回一个使用自定义DNS解析器的HTTP客户端
+func GetHTTPClient(timeout time.Duration) *http.Client {
+	if timeout <= 0 {
+		timeout = 30 * time.Second
+	}
+
+	customResolver := GetCustomResolver()
+
+	return &http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyFromEnvironment,
+			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				host, port, err := net.SplitHostPort(addr)
+				if err != nil {
+					return nil, err
+				}
+				ips, err := customResolver.LookupHost(ctx, host)
+				if err != nil {
+					return nil, err
+				}
+				for _, ip := range ips {
+					dialer := &net.Dialer{
+						Timeout:   30 * time.Second,
+						KeepAlive: 30 * time.Second,
+						DualStack: true,
+					}
+					conn, err := dialer.DialContext(ctx, network, net.JoinHostPort(ip, port))
+					if err == nil {
+						return conn, nil
+					}
+				}
+				return nil, fmt.Errorf("failed to dial to any of the resolved IPs")
+			},
+			MaxIdleConns:          10,
+			IdleConnTimeout:       90 * time.Second,
+			TLSHandshakeTimeout:   10 * time.Second,
+			ExpectContinueTimeout: 1 * time.Second,
+		},
+		Timeout: timeout,
+	}
+}
+
+// GetNetDialer 返回一个使用自定义DNS解析器的网络拨号器
+func GetNetDialer(timeout time.Duration) *net.Dialer {
+	if timeout <= 0 {
+		timeout = 5 * time.Second
+	}
+
+	return &net.Dialer{
+		Timeout:   timeout,
+		KeepAlive: 30 * time.Second,
+		Resolver:  GetCustomResolver(),
+	}
+}