optimize: TCP 和 UDP 类型的DNS，只接收响应一次。

packages/mitmproxy/src/lib/dns/tcp.js

@@ -37,13 +37,13 @@ module.exports = class DNSOverTCP extends BaseDNS {
         tcpClient.write(Buffer.concat([lengthBuffer, packet]))
       })
 
-      tcpClient.on('data', (data) => {
+      tcpClient.once('data', (data) => {
         const length = data.readUInt16BE(0)
         const response = dnsPacket.decode(data.subarray(2, 2 + length))
         resolve(response)
       })
 
-      tcpClient.on('error', (err) => {
+      tcpClient.once('error', (err) => {
         reject(err)
       })
     })

packages/mitmproxy/src/lib/dns/udp.js

@@ -35,7 +35,7 @@ module.exports = class DNSOverUDP extends BaseDNS {
       })
 
       // 接收 UDP 响应
-      udpClient.on('message', (msg) => {
+      udpClient.once('message', (msg) => {
         const response = dnsPacket.decode(msg)
         resolve(response)
       })

packages/mitmproxy/test/dnsTest.mjs

@@ -106,9 +106,9 @@ let ip
 
 console.log('\n--------------- test PreSet ---------------\n')
 ip = await dnsProviders.PreSet.lookup(presetHostname)
-assert.strictEqual(ip, presetIp) // test preset
 console.log('===> test PreSet:', ip, '\n\n')
 console.log('\n\n')
+assert.strictEqual(ip, presetIp) // test preset
 
 
 console.log('\n--------------- test https ---------------\n')