Add client_transfer example

examples/client_transfer/client_transfer.js

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+// Demonstrates following a server-initiated Transfer packet (added in 1.20.5, used by
+// the vanilla /transfer command and by proxies/plugins that hand a player off to a
+// different server, e.g. for load balancing or a low-latency regional server).
+//
+// The important part is the reconnect: end() the current connection and wait for it to
+// fully close, then wait a short beat, before connecting to the new host:port with the
+// same username. Reconnecting immediately can race the server's own cleanup of the old
+// session and get rejected with "already playing on the server" (Bukkit/Paper's
+// duplicate-login check), since the server hasn't necessarily finished processing the
+// old connection's teardown yet.
+const mc = require('minecraft-protocol')
+
+if (process.argv.length < 4 || process.argv.length > 6) {
+  console.log('Usage : node client_transfer.js <host> <port> [<name>]')
+  process.exit(1)
+}
+
+const host = process.argv[2]
+const port = parseInt(process.argv[3])
+const username = process.argv[4] || 'transfer_bot'
+
+function connect (host, port) {
+  const client = mc.createClient({ host, port, username })
+
+  client.on('connect', () => console.log(`connecting to ${host}:${port}`))
+  client.on('login', () => console.log(`logged in to ${host}:${port}`))
+  client.on('error', (err) => console.error('error:', err))
+  client.on('disconnect', (packet) => console.log('disconnected:', packet.reason))
+  client.on('kick_disconnect', (packet) => console.log('kicked:', packet.reason))
+
+  client.on('transfer', async (packet) => {
+    console.log(`received transfer packet -> ${packet.host}:${packet.port}, reconnecting`)
+    await new Promise((resolve) => {
+      client.once('end', resolve)
+      client.end()
+    })
+    await new Promise((resolve) => setTimeout(resolve, 500))
+    connect(packet.host, packet.port)
+  })
+
+  return client
+}
+
+connect(host, port)

examples/client_transfer/package.json

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+{
+  "name": "node-minecraft-protocol-example",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+  },
+  "description": "A node-minecraft-protocol example"
+}