javascript - 获取有关数据响应的 TCP 套接字特定数据

Question

我编写了以下函数:

  let responses = {}
  let socks = {}
  module.ping = function (port, address) {
    //console.log(`Ping function was called - ${address} ${port}`)
    if (socks[`${address}:${port}`]) {
      //console.log("Using existing socket")
      responses[`${address}:${port}`] = false
      sock = socks[`${address}:${port}`]
      sock.write('PING\n')
      console.log(`Sent PING to ${address} ${port}`)
    }
    else {
      sock = new net.Socket();
      responses[`${address}:${port}`] = false
      sock.connect(port, address, async function() {
        sock.write('PING\n')
        console.log(`Sent PING to ${address} ${port}`)
      });

      // Response listeners
      sock.on('data', function(data) {
        clean_data = data.toString().replace(/\n/g, '').replace(/\r/g, '')
        console.log(`[${sock.remoteAddress}:${sock.remotePort}] Received ${clean_data}`)
          if (clean_data == 'PONG') {
            //console.log(`[${sock.remoteAddress}:${sock.remotePort}] Received PONG`)
            //sock.end()
            //delete socks[`${address}:${port}`]
            responses[`${sock.remoteAddress}:${sock.remotePort}`] = true
          }
        }
      });
      sock.on('error', function(error) { 
        if (sock.remoteAddress) {
          responses[`${sock.remoteAddress}:${sock.remotePort}`] = false
        }
        sock.destroy()
        delete socks[`${address}:${port}`]
      });

      // Add to list of sockets
      if (sock) {
        socks[`${address}:${port}`] = sock 
      }
    }
  }

在另一端，我有一个监听 TCP 服务器，它简单地响应“PONG\n”。当我尝试单个主机时，我得到了预期的输出:

module.ping(1337, 10.0.0.100)
await delay(5000) // Custom function
module.ping(1337, 10.0.0.100)

Sent PING to 10.0.0.100 1337

[10.0.0.100:1337] Received PONG

Sent PING to 10.0.0.100 1337

[10.0.0.100:1337] Received PONG

但是，当我尝试攻击多个主机时:

module.ping(1337, 10.0.0.100)
module.ping(1337, 10.0.0.200)
await delay(5000) // Custom function
module.ping(1337, 10.0.0.100)
module.ping(1337, 10.0.0.200)

Sent PING to 10.0.0.100 1337

Sent PING to 10.0.0.200 1337

[10.0.0.200:1337] Received PONG

[10.0.0.200:1337] Received PONG

Sent PING to 10.0.0.100 1337

Sent PING to 10.0.0.200 1337

[10.0.0.200:1337] Received PONG

[10.0.0.200:1337] Received PONG

在我看来，我添加的“数据”事件监听器以某种方式绑定(bind)到我的代码中的错误地址，但我看不到位置。如果我向列表中添加更多主机，最后发送 PING 的主机就是所有 PONG 都被标记为其中一部分的主机。

Answer 1

对于初学者，我没有看到 sock 变量的声明，这意味着它在某个更高的范围内，并且在正在进行的不同异步操作之间被错误地混淆或打败了。

在本地声明该变量，这样每次使用它都是一个单独的变量，并且一个异步操作不会覆盖您用于另一操作的那个。必须在本地声明所有并非特意用于更高范围和共享的变量。

我不知道这是否是这里唯一的问题，但它确实是一个问题。例如，如果您连续两次调用 .ping() 并且必须创建两个新套接字，则第二个套接字将覆盖 之前的 sock 变量。 connect() 成功导致您将 PING 发送到错误的 sock，这正是您的诊断日志所显示的。