Initial commit

core/connect/direct.go

@@ -0,0 +1,93 @@
+package connect
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"time"
+
+	"go.uber.org/zap"
+)
+
+// DirectFactory Direct-UDP 直连工厂（Layer 1）
+type DirectFactory struct {
+	stunServers []string
+	logger      *zap.Logger
+}
+
+// NewDirectFactory 创建 Direct-UDP 工厂
+func NewDirectFactory(stunServers []string, logger *zap.Logger) *DirectFactory {
+	return &DirectFactory{
+		stunServers: stunServers,
+		logger:      logger,
+	}
+}
+
+// Layer 返回传输层类型
+func (f *DirectFactory) Layer() Layer {
+	return LayerDirectUDP
+}
+
+// Name 返回传输方式名称
+func (f *DirectFactory) Name() string {
+	return "Direct-UDP"
+}
+
+// Dial 建立 Direct-UDP 直连
+func (f *DirectFactory) Dial(ctx context.Context, config *DialConfig) (net.Conn, error) {
+	f.logger.Info("开始建立 Direct-UDP 直连",
+		zap.String("peer_id", config.PeerID))
+
+	servers := f.stunServers
+	if len(servers) == 0 {
+		servers = config.STUNServers
+	}
+
+	if len(servers) == 0 {
+		f.logger.Warn("未配置 STUN 服务器列表，仅尝试内部 P2P 打洞")
+	}
+
+	var candidates []string
+	if len(servers) > 0 {
+		// 1. 创建 STUN 客户端收集候选地址
+		stun := NewSTUNClient(servers, f.logger)
+		candidates = stun.CollectCandidates()
+	}
+
+	if len(candidates) == 0 {
+		f.logger.Warn("未能收集到任何 STUN 候选地址，回退至 PeerID")
+		// As a fallback, maybe PeerID contains IP:PORT
+		candidates = append(candidates, config.PeerID)
+	}
+
+	f.logger.Info("STUN 候选地址收集完成",
+		zap.Strings("candidates", candidates))
+
+	// 2. 实际 P2P 连接尝试
+	f.logger.Warn("当前尝试所有候选地址...")
+
+	dialer := &net.Dialer{
+		Timeout: 5 * time.Second,
+	}
+
+	// 建立 UDP 连接并返回最近可用的
+	var lastErr error
+	for _, candidate := range candidates {
+		if candidate == "" { continue }
+		
+		conn, err := dialer.DialContext(ctx, "udp", candidate)
+		if err == nil {
+			f.logger.Info("Direct-UDP 直连建立成功",
+				zap.String("peer_id", config.PeerID),
+				zap.String("remote_addr", conn.RemoteAddr().String()))
+			return conn, nil
+		}
+		
+		f.logger.Warn("候选地址连接失败",
+			zap.String("candidate", candidate),
+			zap.Error(err))
+		lastErr = err
+	}
+
+	return nil, fmt.Errorf("所有候选地址 UDP 连接均失败，最后错误：%w", lastErr)
+}