dgram: support for setting socket buffer size

* setRecvBufferSize(int) and setSendBufferSize(int)
* added docs for send/receive buffer sizes
* Added options support to set buffer sizes in
  dgram.createSocket().

PR-URL: https://github.com/nodejs/node/pull/13623
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 45 insertions, 0 deletions

diff --git a/lib/dgram.js b/lib/dgram.js
index 9e9806f5b0..fa2f476096 100644
--- a/lib/dgram.js
+++ b/lib/dgram.js
@@ -98,15 +98,19 @@ function _createSocketHandle(address, port, addressType, fd, flags) {
   return handle;
 }
 
+const kOptionSymbol = Symbol('options symbol');
 
 function Socket(type, listener) {
   EventEmitter.call(this);
   var lookup;
 
+  this[kOptionSymbol] = {};
   if (type !== null && typeof type === 'object') {
     var options = type;
     type = options.type;
     lookup = options.lookup;
+    this[kOptionSymbol].recvBufferSize = options.recvBufferSize;
+    this[kOptionSymbol].sendBufferSize = options.sendBufferSize;
   }
 
   var handle = newHandle(type, lookup);
@@ -141,6 +145,12 @@ function startListening(socket) {
   socket._bindState = BIND_STATE_BOUND;
   socket.fd = -42; // compatibility hack
 
+  if (socket[kOptionSymbol].recvBufferSize)
+    bufferSize(socket, socket[kOptionSymbol].recvBufferSize, 'recv');
+
+  if (socket[kOptionSymbol].sendBufferSize)
+    bufferSize(socket, socket[kOptionSymbol].sendBufferSize, 'send');
+
   socket.emit('listening');
 }
 
@@ -157,6 +167,20 @@ function replaceHandle(self, newHandle) {
   self._handle = newHandle;
 }
 
+function bufferSize(self, size, buffer) {
+  if (size >>> 0 !== size)
+    throw new errors.TypeError('ERR_SOCKET_BAD_BUFFER_SIZE');
+
+  try {
+    if (buffer === 'recv')
+      return self._handle.bufferSize(size, 0);
+    else
+      return self._handle.bufferSize(size, 1);
+  } catch (e) {
+    throw new errors.Error('ERR_SOCKET_BUFFER_SIZE', e);
+  }
+}
+
 Socket.prototype.bind = function(port_, address_ /*, callback*/) {
   let port = port_;
 
@@ -636,6 +660,27 @@ Socket.prototype.unref = function() {
   return this;
 };
 
+
+Socket.prototype.setRecvBufferSize = function(size) {
+  bufferSize(this, size, 'recv');
+};
+
+
+Socket.prototype.setSendBufferSize = function(size) {
+  bufferSize(this, size, 'send');
+};
+
+
+Socket.prototype.getRecvBufferSize = function() {
+  return bufferSize(this, 0, 'recv');
+};
+
+
+Socket.prototype.getSendBufferSize = function() {
+  return bufferSize(this, 0, 'send');
+};
+
+
 module.exports = {
   _createSocketHandle,
   createSocket,