dgram: implement socket.bind({ fd })

dgram: Implement binding an existing `fd`. Allow pass a `fd` property
to `socket.bind()` in dgram.
src: Add `UDPWrap::Open`

PR-URL: https://github.com/nodejs/node/pull/21745
Fixes: https://github.com/nodejs/node/issues/14961
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

1 files changed, 27 insertions, 12 deletions

diff --git a/lib/internal/dgram.js b/lib/internal/dgram.js
index 82b65294c2..e9b5364c8e 100644
--- a/lib/internal/dgram.js
+++ b/lib/internal/dgram.js
@@ -1,7 +1,9 @@
 'use strict';
-const assert = require('assert');
 const { codes } = require('internal/errors');
 const { UDP } = process.binding('udp_wrap');
+const { isInt32 } = require('internal/validators');
+const TTYWrap = process.binding('tty_wrap');
+const { UV_EINVAL } = process.binding('uv');
 const { ERR_INVALID_ARG_TYPE, ERR_SOCKET_BAD_TYPE } = codes;
 const kStateSymbol = Symbol('state symbol');
 let dns;  // Lazy load for startup performance.
@@ -17,6 +19,9 @@ function lookup6(lookup, address, callback) {
 }
 
 
+const guessHandleType = TTYWrap.guessHandleType;
+
+
 function newHandle(type, lookup) {
   if (lookup === undefined) {
     if (dns === undefined) {
@@ -49,22 +54,32 @@ function newHandle(type, lookup) {
 
 
 function _createSocketHandle(address, port, addressType, fd, flags) {
-  // Opening an existing fd is not supported for UDP handles.
-  assert(typeof fd !== 'number' || fd < 0);
-
   const handle = newHandle(addressType);
-
-  if (port || address) {
-    const err = handle.bind(address, port || 0, flags);
-
-    if (err) {
-      handle.close();
-      return err;
+  let err;
+
+  if (isInt32(fd) && fd > 0) {
+    const type = guessHandleType(fd);
+    if (type !== 'UDP') {
+      err = UV_EINVAL;
+    } else {
+      err = handle.open(fd);
     }
+  } else if (port || address) {
+    err = handle.bind(address, port || 0, flags);
+  }
+
+  if (err) {
+    handle.close();
+    return err;
   }
 
   return handle;
 }
 
 
-module.exports = { kStateSymbol, _createSocketHandle, newHandle };
+module.exports = {
+  kStateSymbol,
+  _createSocketHandle,
+  newHandle,
+  guessHandleType,
+};