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: #13623
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/dgram.md

@@ -227,6 +227,20 @@ never have reason to call this.
 If `multicastInterface` is not specified, the operating system will attempt to
 drop membership on all valid interfaces.
 
+### socket.getRecvBufferSize(size)
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns {number} the `SO_RCVBUF` socket receive buffer size in bytes.
+
+### socket.getSendBufferSize(size)
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns {number} the `SO_SNDBUF` socket send buffer size in bytes.
+
 ### socket.ref()
 <!-- YAML
 added: v0.9.1
@@ -476,6 +490,26 @@ decremented to 0 by a router, it will not be forwarded.
 The argument passed to to `socket.setMulticastTTL()` is a number of hops
 between 0 and 255. The default on most systems is `1` but can vary.
 
+### socket.setRecvBufferSize(size)
+<!-- YAML
+added: REPLACEME
+-->
+
+* `size` {number} Integer
+
+Sets the `SO_RCVBUF` socket option. Sets the maximum socket receive buffer
+in bytes.
+
+### socket.setSendBufferSize(size)
+<!-- YAML
+added: REPLACEME
+-->
+
+* `size` {number} Integer
+
+Sets the `SO_SNDBUF` socket option. Sets the maximum socket send buffer
+in bytes.
+
 ### socket.setTTL(ttl)
 <!-- YAML
 added: v0.1.101
@@ -539,6 +573,9 @@ changes:
   - version: v8.6.0
     pr-url: https://github.com/nodejs/node/pull/14560
     description: The `lookup` option is supported.
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/13623
+    description: `recvBufferSize` and `sendBufferSize` options are supported now.
 -->
 
 * `options` {Object} Available options are:
@@ -547,6 +584,8 @@ changes:
   * `reuseAddr` {boolean} When `true` [`socket.bind()`][] will reuse the
     address, even if another process has already bound a socket on it. Optional.
     Defaults to `false`.
+  * `recvBufferSize` {number} - Optional. Sets the `SO_RCVBUF` socket value.
+  * `sendBufferSize` {number} - Optional. Sets the `SO_SNDBUF` socket value.
   * `lookup` {Function} Custom lookup function. Defaults to [`dns.lookup()`][].
     Optional.
 * `callback` {Function} Attached as a listener for `'message'` events. Optional.

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_;
 
@@ -651,6 +675,27 @@ 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,

src/udp_wrap.cc

@@ -46,6 +46,7 @@ using v8::Object;
 using v8::PropertyAttribute;
 using v8::PropertyCallbackInfo;
 using v8::String;
+using v8::Uint32;
 using v8::Undefined;
 using v8::Value;
 
@@ -135,6 +136,7 @@ void UDPWrap::Initialize(Local<Object> target,
   env->SetProtoMethod(t, "setMulticastLoopback", SetMulticastLoopback);
   env->SetProtoMethod(t, "setBroadcast", SetBroadcast);
   env->SetProtoMethod(t, "setTTL", SetTTL);
+  env->SetProtoMethod(t, "bufferSize", BufferSize);
 
   env->SetProtoMethod(t, "ref", HandleWrap::Ref);
   env->SetProtoMethod(t, "unref", HandleWrap::Unref);
@@ -223,6 +225,43 @@ void UDPWrap::Bind6(const FunctionCallbackInfo<Value>& args) {
 }
 
 
+void UDPWrap::BufferSize(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  UDPWrap* wrap;
+  ASSIGN_OR_RETURN_UNWRAP(&wrap,
+                          args.Holder(),
+                          args.GetReturnValue().Set(UV_EBADF));
+
+  CHECK(args[0]->IsUint32());
+  CHECK(args[1]->IsUint32());
+  int size = static_cast<int>(args[0].As<Uint32>()->Value());
+
+  if (size != args[0].As<Uint32>()->Value()) {
+    if (args[1].As<Uint32>()->Value() == 0)
+      return env->ThrowUVException(EINVAL, "uv_recv_buffer_size");
+    else
+      return env->ThrowUVException(EINVAL, "uv_send_buffer_size");
+  }
+
+  int err;
+  if (args[1].As<Uint32>()->Value() == 0) {
+    err = uv_recv_buffer_size(reinterpret_cast<uv_handle_t*>(&wrap->handle_),
+                              &size);
+  } else {
+    err = uv_send_buffer_size(reinterpret_cast<uv_handle_t*>(&wrap->handle_),
+                              &size);
+  }
+
+  if (err != 0) {
+    if (args[1].As<Uint32>()->Value() == 0)
+      return env->ThrowUVException(err, "uv_recv_buffer_size");
+    else
+      return env->ThrowUVException(err, "uv_send_buffer_size");
+  }
+  args.GetReturnValue().Set(size);
+}
+
+
 #define X(name, fn)                                                           \
   void UDPWrap::name(const FunctionCallbackInfo<Value>& args) {               \
     UDPWrap* wrap = Unwrap<UDPWrap>(args.Holder());                           \

src/udp_wrap.h

@@ -57,6 +57,7 @@ class UDPWrap: public HandleWrap {
       const v8::FunctionCallbackInfo<v8::Value>& args);
   static void SetBroadcast(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void SetTTL(const v8::FunctionCallbackInfo<v8::Value>& args);
+  static void BufferSize(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   static v8::Local<v8::Object> Instantiate(Environment* env, AsyncWrap* parent);
   uv_udp_t* UVHandle();

test/parallel/test-dgram-createSocket-type.js

@@ -39,3 +39,23 @@ validTypes.forEach((validType) => {
     socket.close();
   });
 });
+
+// Ensure buffer sizes can be set
+{
+  const socket = dgram.createSocket({
+    type: 'udp4',
+    recvBufferSize: 10000,
+    sendBufferSize: 15000
+  });
+
+  socket.bind(common.mustCall(() => {
+    // note: linux will double the buffer size
+    assert.ok(socket.getRecvBufferSize() === 10000 ||
+              socket.getRecvBufferSize() === 20000,
+              'SO_RCVBUF not 1300 or 2600');
+    assert.ok(socket.getSendBufferSize() === 15000 ||
+              socket.getSendBufferSize() === 30000,
+              'SO_SNDBUF not 1800 or 3600');
+    socket.close();
+  }));
+}

test/parallel/test-dgram-socket-buffer-size.js

@@ -0,0 +1,74 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const dgram = require('dgram');
+
+{
+  // Should throw error if the socket is never bound.
+  const errorObj = {
+    code: 'ERR_SOCKET_BUFFER_SIZE',
+    type: Error,
+    message: /^Could not get or set buffer size:.*$/
+  };
+
+  const socket = dgram.createSocket('udp4');
+
+  assert.throws(() => {
+    socket.setRecvBufferSize(8192);
+  }, common.expectsError(errorObj));
+
+  assert.throws(() => {
+    socket.setSendBufferSize(8192);
+  }, common.expectsError(errorObj));
+
+  assert.throws(() => {
+    socket.getRecvBufferSize();
+  }, common.expectsError(errorObj));
+
+  assert.throws(() => {
+    socket.getSendBufferSize();
+  }, common.expectsError(errorObj));
+}
+
+{
+  // Should throw error if invalid buffer size is specified
+  const errorObj = {
+    code: 'ERR_SOCKET_BAD_BUFFER_SIZE',
+    type: TypeError,
+    message: /^Buffer size must be a positive integer$/
+  };
+
+  const badBufferSizes = [-1, Infinity, 'Doh!'];
+
+  const socket = dgram.createSocket('udp4');
+
+  socket.bind(common.mustCall(() => {
+    badBufferSizes.forEach((badBufferSize) => {
+      assert.throws(() => {
+        socket.setRecvBufferSize(badBufferSize);
+      }, common.expectsError(errorObj));
+
+      assert.throws(() => {
+        socket.setSendBufferSize(badBufferSize);
+      }, common.expectsError(errorObj));
+    });
+    socket.close();
+  }));
+}
+
+{
+  // Can set and get buffer sizes after binding the socket.
+  const socket = dgram.createSocket('udp4');
+
+  socket.bind(common.mustCall(() => {
+    socket.setRecvBufferSize(10000);
+    socket.setSendBufferSize(10000);
+
+    // note: linux will double the buffer size
+    const expectedBufferSize = common.isLinux ? 20000 : 10000;
+    assert.strictEqual(socket.getRecvBufferSize(), expectedBufferSize);
+    assert.strictEqual(socket.getSendBufferSize(), expectedBufferSize);
+    socket.close();
+  }));
+}