add socket option everywhere and streamline internals

lib/io.js

@@ -237,25 +237,26 @@ class Request {
   reply (value, opts = {}) {
     const socket = opts.socket || this.socket
     const to = opts.to || this.from
-    this._sendReply(0, value || null, opts.token !== false, this.target !== null && opts.closerNodes !== false, to, socket)
+    this._sendReply(0, value || null, opts.token !== false, opts.closerNodes !== false, to, socket)
   }
 
   error (code, opts = {}) {
     const socket = opts.socket || this.socket
     const to = opts.to || this.from
-    this._sendReply(code, null, opts.token === true, this.target !== null && opts.closerNodes !== false, to, socket)
+    this._sendReply(code, null, opts.token === true, opts.closerNodes !== false, to, socket)
   }
 
-  relay (value, to) {
-    const buffer = this._encodeRequest(null, value)
-    this.socket.send(buffer, 0, buffer.byteLength, to.port, to.host)
+  relay (value, to, opts) {
+    const socket = (opts && opts.socket) || this.socket
+    const buffer = this._encodeRequest(null, value, socket)
+    socket.send(buffer, 0, buffer.byteLength, to.port, to.host)
   }
 
   send (force = false) {
     if (this.destroyed) return
 
     if (this.socket === null) return
-    if (this._buffer === null) this._buffer = this._encodeRequest(this.token, this.value)
+    if (this._buffer === null) this._buffer = this._encodeRequest(this.token, this.value, this.socket)
 
     if (!force && this._io.congestion.isFull()) {
       this._io._pending.push(this)
@@ -295,7 +296,7 @@ class Request {
     if (socket === null || this.destroyed) return
 
     const id = this._io.ephemeral === false && socket === this._io.serverSocket
-    const closerNodes = hasCloserNodes ? this._io.table.closest(this.target) : EMPTY_ARRAY
+    const closerNodes = (this.target !== null && hasCloserNodes) ? this._io.table.closest(this.target) : EMPTY_ARRAY
     const state = { start: 0, end: 1 + 1 + 6 + 2, buffer: null } // (type | version) + flags + to + tid
 
     if (id) state.end += 32
@@ -320,8 +321,8 @@ class Request {
     socket.send(state.buffer, 0, state.buffer.byteLength, from.port, from.host)
   }
 
-  _encodeRequest (token, value) {
-    const id = this._io.ephemeral === false && this.socket === this._io.serverSocket
+  _encodeRequest (token, value, socket) {
+    const id = this._io.ephemeral === false && socket === this._io.serverSocket
     const state = { start: 0, end: 1 + 1 + 6 + 2, buffer: null } // (type | version) + flags + to + tid
 
     if (id) state.end += 32