Fix: 增强SSH会话管理和错误处理

- 添加会话创建重试机制(最多3次)
- 允许部分命令失败而不中断整个扫描
- 改进错误提示和日志输出
- 解决H3C设备LLDP命令会话拒绝问题

internal/device/parser.go

@@ -1,6 +1,7 @@
 package device
 
 import (
+	"fmt"
 	"network-topology-discovery/pkg/models"
 	sshclient "network-topology-discovery/internal/ssh"
 )
@@ -74,12 +75,17 @@ func DiscoverDevice(ip string, deviceType models.DeviceType, username, password
 	// 获取命令列表
 	commands := parser.GetCommands()
 
-	// 执行命令
-	outputs, err := client.ExecuteCommands(commands)
-	if err != nil {
-		device.ScanStatus = "failed"
-		device.ErrorMessage = err.Error()
-		return device, err
+	// 执行命令 - 允许部分命令失败
+	outputs := make([]string, 0, len(commands))
+	for _, cmd := range commands {
+		output, err := client.ExecuteCommand(cmd)
+		if err != nil {
+			// 记录警告但继续执行其他命令
+			fmt.Printf("Warning: command '%s' failed: %v\n", cmd, err)
+			outputs = append(outputs, "")
+		} else {
+			outputs = append(outputs, output)
+		}
 	}
 
 	// 解析输出

internal/ssh/client.go

@@ -121,9 +121,25 @@ func (c *Client) ExecuteCommand(command string) (string, error) {
 		return "", fmt.Errorf("not connected")
 	}
 
-	session, err := c.client.NewSession()
+	// 重试机制,处理会话创建失败的情况
+	var session *ssh.Session
+	var err error
+	maxRetries := 3
+	
+	for i := 0; i < maxRetries; i++ {
+		session, err = c.client.NewSession()
+		if err == nil {
+			break
+		}
+		
+		// 如果是会话拒绝错误,等待后重试
+		if i < maxRetries-1 {
+			time.Sleep(time.Duration(i+1) * 500 * time.Millisecond)
+		}
+	}
+	
 	if err != nil {
-		return "", fmt.Errorf("failed to create session: %w", err)
+		return "", fmt.Errorf("failed to create session after %d retries: %w", maxRetries, err)
 	}
 	defer session.Close()