net,dgram: add ipv6Only option for net and dgram

For TCP servers, the dual-stack support is enable by default, i.e.
binding host "::" will also make "0.0.0.0" bound. This commit add
ipv6Only option in `net.Server.listen()` and `dgram.createSocket()`
methods which allows to disable dual-stack support. Support for
cluster module is also provided in this commit.

Fixes: #17664

PR-URL: #23798
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/dgram.md

@@ -601,6 +601,9 @@ changes:
     pr-url: https://github.com/nodejs/node/pull/13623
     description: The `recvBufferSize` and `sendBufferSize` options are
                  supported now.
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/23798
+    description: The `ipv6Only` option is supported.
 -->
 
 * `options` {Object} Available options are:
@@ -609,6 +612,9 @@ changes:
   * `reuseAddr` {boolean} When `true` [`socket.bind()`][] will reuse the
     address, even if another process has already bound a socket on it.
     **Default:** `false`.
+  * `ipv6Only` {boolean} Setting `ipv6Only` to `true` will
+    disable dual-stack support, i.e., binding to address `::` won't make
+    `0.0.0.0` be bound. **Default:** `false`.
   * `recvBufferSize` {number} - Sets the `SO_RCVBUF` socket value.
   * `sendBufferSize` {number} - Sets the `SO_SNDBUF` socket value.
   * `lookup` {Function} Custom lookup function. **Default:** [`dns.lookup()`][].

doc/api/net.md

@@ -252,6 +252,10 @@ Listening on a file descriptor is not supported on Windows.
 #### server.listen(options[, callback])
 <!-- YAML
 added: v0.11.14
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/23798
+    description: The `ipv6Only` option is supported.
 -->
 
 * `options` {Object} Required. Supports the following properties:
@@ -266,6 +270,9 @@ added: v0.11.14
     for all users. **Default:** `false`
   * `writableAll` {boolean} For IPC servers makes the pipe writable
     for all users. **Default:** `false`
+  * `ipv6Only` {boolean} For TCP servers, setting `ipv6Only` to `true` will
+    disable dual-stack support, i.e., binding to host `::` won't make
+    `0.0.0.0` be bound. **Default:** `false`.
 * `callback` {Function} Common parameter of [`server.listen()`][]
   functions.
 * Returns: {net.Server}

lib/dgram.js

@@ -54,7 +54,11 @@ const {
 } = require('internal/async_hooks');
 const { UV_UDP_REUSEADDR } = internalBinding('constants').os;
 
-const { UDP, SendWrap } = internalBinding('udp_wrap');
+const {
+  constants: { UV_UDP_IPV6ONLY },
+  UDP,
+  SendWrap
+} = internalBinding('udp_wrap');
 
 const BIND_STATE_UNBOUND = 0;
 const BIND_STATE_BINDING = 1;
@@ -99,6 +103,7 @@ function Socket(type, listener) {
     bindState: BIND_STATE_UNBOUND,
     queue: undefined,
     reuseAddr: options && options.reuseAddr, // Use UV_UDP_REUSEADDR if true.
+    ipv6Only: options && options.ipv6Only,
     recvBufferSize,
     sendBufferSize
   };
@@ -270,6 +275,8 @@ Socket.prototype.bind = function(port_, address_ /* , callback */) {
     var flags = 0;
     if (state.reuseAddr)
       flags |= UV_UDP_REUSEADDR;
+    if (state.ipv6Only)
+      flags |= UV_UDP_IPV6ONLY;
 
     if (cluster.isWorker && !exclusive) {
       bindServerHandle(this, {

lib/internal/cluster/round_robin_handle.js

@@ -3,10 +3,11 @@ const assert = require('assert');
 const net = require('net');
 const { sendHelper } = require('internal/cluster/utils');
 const uv = internalBinding('uv');
+const { constants } = internalBinding('tcp_wrap');
 
 module.exports = RoundRobinHandle;
 
-function RoundRobinHandle(key, address, port, addressType, fd) {
+function RoundRobinHandle(key, address, port, addressType, fd, flags) {
   this.key = key;
   this.all = new Map();
   this.free = [];
@@ -16,9 +17,14 @@ function RoundRobinHandle(key, address, port, addressType, fd) {
 
   if (fd >= 0)
     this.server.listen({ fd });
-  else if (port >= 0)
-    this.server.listen(port, address);
-  else
+  else if (port >= 0) {
+    this.server.listen({
+      port,
+      host: address,
+      // Currently, net module only supports `ipv6Only` option in `flags`.
+      ipv6Only: Boolean(flags & constants.UV_TCP_IPV6ONLY),
+    });
+  } else
     this.server.listen(address);  // UNIX socket path.
 
   this.server.once('listening', () => {

lib/internal/cluster/shared_handle.js

@@ -15,7 +15,7 @@ function SharedHandle(key, address, port, addressType, fd, flags) {
   if (addressType === 'udp4' || addressType === 'udp6')
     rval = dgram._createSocketHandle(address, port, addressType, fd, flags);
   else
-    rval = net._createServerHandle(address, port, addressType, fd);
+    rval = net._createServerHandle(address, port, addressType, fd, flags);
 
   if (typeof rval === 'number')
     this.errno = rval;

lib/net.js

@@ -97,6 +97,10 @@ const {
 
 function noop() {}
 
+function getFlags(ipv6Only) {
+  return ipv6Only === true ? TCPConstants.UV_TCP_IPV6ONLY : 0;
+}
+
 function createHandle(fd, is_server) {
   validateInt32(fd, 'fd', 0);
   const type = TTYWrap.guessHandleType(fd);
@@ -798,7 +802,7 @@ function checkBindError(err, port, handle) {
 
 
 function internalConnect(
-  self, address, port, addressType, localAddress, localPort) {
+  self, address, port, addressType, localAddress, localPort, flags) {
   // TODO return promise from Socket.prototype.connect which
   // wraps _connectReq.
 
@@ -812,7 +816,7 @@ function internalConnect(
       err = self._handle.bind(localAddress, localPort);
     } else { // addressType === 6
       localAddress = localAddress || '::';
-      err = self._handle.bind6(localAddress, localPort);
+      err = self._handle.bind6(localAddress, localPort, flags);
     }
     debug('binding to localAddress: %s and localPort: %d (addressType: %d)',
           localAddress, localPort, addressType);
@@ -1148,7 +1152,7 @@ util.inherits(Server, EventEmitter);
 function toNumber(x) { return (x = Number(x)) >= 0 ? x : false; }
 
 // Returns handle if it can be created, or error code if it can't
-function createServerHandle(address, port, addressType, fd) {
+function createServerHandle(address, port, addressType, fd, flags) {
   var err = 0;
   // assign handle in listen, and clean up if bind or listen fails
   var handle;
@@ -1187,14 +1191,14 @@ function createServerHandle(address, port, addressType, fd) {
     debug('bind to', address || 'any');
     if (!address) {
       // Try binding to ipv6 first
-      err = handle.bind6('::', port);
+      err = handle.bind6('::', port, flags);
       if (err) {
         handle.close();
         // Fallback to ipv4
         return createServerHandle('0.0.0.0', port);
       }
     } else if (addressType === 6) {
-      err = handle.bind6(address, port);
+      err = handle.bind6(address, port, flags);
     } else {
       err = handle.bind(address, port);
     }
@@ -1208,7 +1212,7 @@ function createServerHandle(address, port, addressType, fd) {
   return handle;
 }
 
-function setupListenHandle(address, port, addressType, backlog, fd) {
+function setupListenHandle(address, port, addressType, backlog, fd, flags) {
   debug('setupListenHandle', address, port, addressType, backlog, fd);
 
   // If there is not yet a handle, we need to create one and bind.
@@ -1222,7 +1226,7 @@ function setupListenHandle(address, port, addressType, backlog, fd) {
 
     // Try to bind to the unspecified IPv6 address, see if IPv6 is available
     if (!address && typeof fd !== 'number') {
-      rval = createServerHandle('::', port, 6, fd);
+      rval = createServerHandle('::', port, 6, fd, flags);
 
       if (typeof rval === 'number') {
         rval = null;
@@ -1235,7 +1239,7 @@ function setupListenHandle(address, port, addressType, backlog, fd) {
     }
 
     if (rval === null)
-      rval = createServerHandle(address, port, addressType, fd);
+      rval = createServerHandle(address, port, addressType, fd, flags);
 
     if (typeof rval === 'number') {
       var error = uvExceptionWithHostPort(rval, 'listen', address, port);
@@ -1294,7 +1298,7 @@ function emitListeningNT(self) {
 
 
 function listenInCluster(server, address, port, addressType,
-                         backlog, fd, exclusive) {
+                         backlog, fd, exclusive, flags) {
   exclusive = !!exclusive;
 
   if (cluster === undefined) cluster = require('cluster');
@@ -1303,7 +1307,7 @@ function listenInCluster(server, address, port, addressType,
     // Will create a new handle
     // _listen2 sets up the listened handle, it is still named like this
     // to avoid breaking code that wraps this method
-    server._listen2(address, port, addressType, backlog, fd);
+    server._listen2(address, port, addressType, backlog, fd, flags);
     return;
   }
 
@@ -1312,7 +1316,7 @@ function listenInCluster(server, address, port, addressType,
     port: port,
     addressType: addressType,
     fd: fd,
-    flags: 0
+    flags,
   };
 
   // Get the master's server handle, and listen on it
@@ -1330,7 +1334,7 @@ function listenInCluster(server, address, port, addressType,
     server._handle = handle;
     // _listen2 sets up the listened handle, it is still named like this
     // to avoid breaking code that wraps this method
-    server._listen2(address, port, addressType, backlog, fd);
+    server._listen2(address, port, addressType, backlog, fd, flags);
   }
 }
 
@@ -1353,6 +1357,7 @@ Server.prototype.listen = function(...args) {
     toNumber(args.length > 2 && args[2]);  // (port, host, backlog)
 
   options = options._handle || options.handle || options;
+  const flags = getFlags(options.ipv6Only);
   // (handle[, backlog][, cb]) where handle is an object with a handle
   if (options instanceof TCP) {
     this._handle = options;
@@ -1387,7 +1392,7 @@ Server.prototype.listen = function(...args) {
     // start TCP server listening on host:port
     if (options.host) {
       lookupAndListen(this, options.port | 0, options.host, backlog,
-                      options.exclusive);
+                      options.exclusive, flags);
     } else { // Undefined host, listens on unspecified address
       // Default addressType 4 will be used to search for master server
       listenInCluster(this, null, options.port | 0, 4,
@@ -1434,15 +1439,15 @@ Server.prototype.listen = function(...args) {
   throw new ERR_INVALID_OPT_VALUE('options', util.inspect(options));
 };
 
-function lookupAndListen(self, port, address, backlog, exclusive) {
+function lookupAndListen(self, port, address, backlog, exclusive, flags) {
   if (dns === undefined) dns = require('dns');
   dns.lookup(address, function doListen(err, ip, addressType) {
     if (err) {
       self.emit('error', err);
     } else {
       addressType = ip ? addressType : 4;
       listenInCluster(self, ip, port, addressType,
-                      backlog, undefined, exclusive);
+                      backlog, undefined, exclusive, flags);
     }
   });
 }

src/tcp_wrap.cc

@@ -127,6 +127,7 @@ void TCPWrap::Initialize(Local<Object> target,
   Local<Object> constants = Object::New(env->isolate());
   NODE_DEFINE_CONSTANT(constants, SOCKET);
   NODE_DEFINE_CONSTANT(constants, SERVER);
+  NODE_DEFINE_CONSTANT(constants, UV_TCP_IPV6ONLY);
   target->Set(context,
               env->constants_string(),
               constants).FromJust();
@@ -252,13 +253,15 @@ void TCPWrap::Bind6(const FunctionCallbackInfo<Value>& args) {
   Environment* env = wrap->env();
   node::Utf8Value ip6_address(env->isolate(), args[0]);
   int port;
+  unsigned int flags;
   if (!args[1]->Int32Value(env->context()).To(&port)) return;
+  if (!args[2]->Uint32Value(env->context()).To(&flags)) return;
   sockaddr_in6 addr;
   int err = uv_ip6_addr(*ip6_address, port, &addr);
   if (err == 0) {
     err = uv_tcp_bind(&wrap->handle_,
                       reinterpret_cast<const sockaddr*>(&addr),
-                      0);
+                      flags);
   }
   args.GetReturnValue().Set(err);
 }

src/udp_wrap.cc

@@ -149,6 +149,12 @@ void UDPWrap::Initialize(Local<Object> target,
   target->Set(env->context(),
               sendWrapString,
               swt->GetFunction(env->context()).ToLocalChecked()).FromJust();
+
+  Local<Object> constants = Object::New(env->isolate());
+  NODE_DEFINE_CONSTANT(constants, UV_UDP_IPV6ONLY);
+  target->Set(context,
+              env->constants_string(),
+              constants).FromJust();
 }
 
 

test/parallel/test-cluster-dgram-ipv6only.js

@@ -0,0 +1,51 @@
+'use strict';
+
+const common = require('../common');
+if (!common.hasIPv6)
+  common.skip('no IPv6 support');
+if (common.isWindows)
+  common.skip('dgram clustering is currently not supported on windows.');
+
+const assert = require('assert');
+const cluster = require('cluster');
+const dgram = require('dgram');
+
+// This test ensures that the `ipv6Only` option in `dgram.createSock()`
+// works as expected.
+if (cluster.isMaster) {
+  cluster.fork().on('exit', common.mustCall((code) => {
+    assert.strictEqual(code, 0);
+  }));
+} else {
+  let waiting = 2;
+  function close() {
+    if (--waiting === 0)
+      cluster.worker.disconnect();
+  }
+
+  const socket1 = dgram.createSocket({
+    type: 'udp6',
+    ipv6Only: true
+  });
+  const socket2 = dgram.createSocket({
+    type: 'udp4',
+  });
+  socket1.on('error', common.mustNotCall());
+  socket2.on('error', common.mustNotCall());
+
+  socket1.bind({
+    port: 0,
+    address: '::',
+  }, common.mustCall(() => {
+    const { port } = socket1.address();
+    socket2.bind({
+      port,
+      address: '0.0.0.0',
+    }, common.mustCall(() => {
+      process.nextTick(() => {
+        socket1.close(close);
+        socket2.close(close);
+      });
+    }));
+  }));
+}