Initial take on passing FDs between processes

lib/net.js

@@ -17,6 +17,8 @@ var accept      = process.accept;
 var close       = process.close;
 var shutdown    = process.shutdown;
 var read        = process.read;
+var recvMsg     = process.recvMsg;
+var sendFD      = process.sendFD;
 var write       = process.write;
 var toRead      = process.toRead;
 var setNoDelay  = process.setNoDelay;
@@ -28,7 +30,6 @@ var EINPROGRESS = process.EINPROGRESS;
 var ENOENT      = process.ENOENT;
 var END_OF_FILE = 42;
 
-
 function Socket (peerInfo) {
   process.EventEmitter.call();
 
@@ -37,7 +38,7 @@ function Socket (peerInfo) {
   // Allocated on demand.
   self.recvBuffer = null;
 
-  self.readWatcher = new IOWatcher()
+  self.readWatcher = new IOWatcher();
   self.readWatcher.callback = function () {
     // If this is the first recv (recvBuffer doesn't exist) or we've used up
     // most of the recvBuffer, allocate a new one.
@@ -47,10 +48,23 @@ function Socket (peerInfo) {
     }
 
     debug('recvBuffer.used ' + self.recvBuffer.used);
-    var bytesRead = read(self.fd,
+    var bytesRead;
+    var receivedFd = -1;
+
+    if (self.type == "unix") {
+      var msgInfo = recvMsg(self.fd,
                             self.recvBuffer,
                             self.recvBuffer.used,
                             self.recvBuffer.length - self.recvBuffer.used);
+      bytesRead = msgInfo[0];
+      receivedFd = msgInfo[1];
+      debug('receivedFd ' + receivedFd);
+    } else {
+      bytesRead = read(self.fd,
+                         self.recvBuffer,
+                         self.recvBuffer.used,
+                         self.recvBuffer.length - self.recvBuffer.used);
+    }
     debug('bytesRead ' + bytesRead + '\n');
 
     if (bytesRead == 0) {
@@ -59,10 +73,15 @@ function Socket (peerInfo) {
       self.emit('eof');
       if (!self.writable) self.forceClose();
     } else {
+      if (receivedFd == -1) {
         var slice = self.recvBuffer.slice(self.recvBuffer.used,
                                           self.recvBuffer.used + bytesRead);
         self.recvBuffer.used += bytesRead;
         self.emit('data', slice);
+      } else {
+        self.recvBuffer.used += bytesRead;
+        self.emit('fd', receivedFd);
+      }
     }
   };
   self.readable = false;
@@ -70,10 +89,16 @@ function Socket (peerInfo) {
   self.sendQueue = [];    // queue of buffers that need to be written to socket
                           // XXX use link list?
   self.sendQueueSize = 0; // in bytes, not to be confused with sendQueue.length!
+  self.sendMessageQueueSize = 0; // number of messages remaining to be sent
   self._doFlush = function () {
-    assert(self.sendQueueSize > 0);
+    /* Socket becomes writeable on connect() but don't flush if there's
+     * nothing actually to write */
+    if ((self.sendQueueSize == 0) && (self.sendMessageQueueSize == 0)) {
+        return;
+    }
     if (self.flush()) {
       assert(self.sendQueueSize == 0);
+      assert(self.sendMessageQueueSize == 0);
       self.emit("drain");
     }
   };
@@ -134,6 +159,7 @@ Socket.prototype._allocateSendBuffer = function () {
   var b = new process.Buffer(1024);
   b.used = 0;
   b.sent = 0;
+  b.isMsg = false;
   this.sendQueue.push(b);
   return b;
 };
@@ -154,6 +180,7 @@ Socket.prototype._sendString = function (data, encoding) {
       }
     }
     // if we didn't find one, take the last
+    // TODO what if this isn't empty but encoding == fd ?
     if (!buffer) {
       buffer = self._sendQueueLast();
       // if last buffer is used up
@@ -166,13 +193,22 @@ Socket.prototype._sendString = function (data, encoding) {
   var charsWritten;
   var bytesWritten;
 
-  if (encoding.toLowerCase() == 'utf8') {
+  // The special encoding "fd" means that data is an integer FD and we want
+  // to pass the FD on the socket with sendmsg()
+  if (encoding == "fd") {
+    buffer.isFd = true;
+    // TODO is this OK -- does it guarantee that the fd is the only thing in the buffer?
+    charsWritten = buffer.asciiWrite(data, buffer.used, buffer.length - buffer.used);
+    bytesWritten = charsWritten;
+  } else if (encoding.toLowerCase() == 'utf8') {
+    buffer.isFd = false;
     charsWritten = buffer.utf8Write(data,
                                     buffer.used,
                                     buffer.length - buffer.used);
     bytesWritten = process.Buffer.utf8Length(data.slice(0, charsWritten));
   } else {
     // ascii
+    buffer.isFd = false;
     charsWritten = buffer.asciiWrite(data,
                                      buffer.used,
                                      buffer.length - buffer.used);
@@ -180,7 +216,11 @@ Socket.prototype._sendString = function (data, encoding) {
   }
 
   buffer.used += bytesWritten;
+  if (buffer.isFd) {
+    self.sendMessageQueueSize += 1;
+  } else {
     self.sendQueueSize += bytesWritten;
+  }
 
   debug('charsWritten ' + charsWritten);
   debug('buffer.used ' + buffer.used);
@@ -235,6 +275,27 @@ Socket.prototype.send = function (data, encoding) {
   return this.flush();
 };
 
+// Sends a file descriptor over a unix socket
+Socket.prototype.sendFD = function(socketToPass) {
+  var self = this;
+
+  if (!self.writable) throw new Error('Socket is not writable');
+
+  if (self._sendQueueLast == END_OF_FILE) {
+    throw new Error('socket.close() called already; cannot write.');
+  }
+
+  if (self.type != "unix") {
+    throw new Error('FD passing only available on unix sockets');
+  }
+
+  if (! socketToPass instanceof Socket) {
+    throw new Error('Provided arg is not a socket');
+  }
+
+  return self.send(socketToPass.fd.toString(), "fd");
+};
+
 
 // Flushes the write buffer out. Emits "drain" if the buffer is empty.
 Socket.prototype.flush = function () {
@@ -253,24 +314,36 @@ Socket.prototype.flush = function () {
 
     if (b.sent == b.used) {
       // this can be improved - save the buffer for later?
-      self.sendQueue.shift()
+      self.sendQueue.shift();
       continue;
     }
 
+    var fdToSend = null;
+    if (b.isFd) {
+      fdToSend = parseInt(b.asciiSlice(b.sent, b.used - b.sent));
+      bytesWritten = sendFD(self.fd, fdToSend);
+    } else {
       bytesWritten = write(self.fd,
                            b,
                            b.sent,
                            b.used - b.sent);
+    }
     if (bytesWritten === null) {
       // could not flush everything
       self.writeWatcher.start();
       assert(self.sendQueueSize > 0);
       return false;
     }
+    if (b.isFd) {
+      b.sent = b.used;
+      self.sendMessageQueueSize -= 1;
+      debug('sent fd: ' + fdToSend);
+    } else {
       b.sent += bytesWritten;
       self.sendQueueSize -= bytesWritten;
       debug('bytes sent: ' + b.sent);
     }
+  }
   self.writeWatcher.stop();
   return true;
 };
@@ -340,7 +413,6 @@ Socket.prototype.address = function () {
   return getsockname(this.fd);
 };
 
-
 Socket.prototype.setNoDelay = function (v) {
   if (this.type == 'tcp') setNoDelay(this.fd, v);
 };
@@ -393,6 +465,7 @@ function Server (listener) {
       debug('accept: ' + JSON.stringify(peerInfo));
       if (!peerInfo) return;
       var peer = new Socket(peerInfo);
+      peer.type = self.type;
       peer.server = self;
       self.emit('connection', peer);
     }

src/node_net2.cc

@@ -41,6 +41,9 @@ static Persistent<String> remote_address_symbol;
 static Persistent<String> remote_port_symbol;
 static Persistent<String> address_symbol;
 static Persistent<String> port_symbol;
+static Persistent<String> type_symbol;
+static Persistent<String> tcp_symbol;
+static Persistent<String> unix_symbol;
 
 #define FD_ARG(a)                                                     \
   if (!(a)->IsInt32()) {                                              \
@@ -181,7 +184,7 @@ static inline Handle<Value> ParseAddressArgs(Handle<Value> first,
     strcpy(un.sun_path, *path);
 
     addr = (struct sockaddr*)&un;
-    addrlen = path.length() + sizeof(un.sun_family);
+    addrlen = path.length() + sizeof(un.sun_family) + 1;
 
   } else {
     // TCP or UDP
@@ -326,7 +329,6 @@ static Handle<Value> Connect(const Arguments& args) {
   return Undefined();
 }
 
-
 static Handle<Value> GetSockName(const Arguments& args) {
   HandleScope scope;
 
@@ -358,6 +360,37 @@ static Handle<Value> GetSockName(const Arguments& args) {
   return scope.Close(info);
 }
 
+static Handle<Value> GetPeerName(const Arguments& args) {
+  HandleScope scope;
+
+  FD_ARG(args[0])
+
+  struct sockaddr_storage address_storage;
+  socklen_t len = sizeof(struct sockaddr_storage);
+
+  int r = getpeername(fd, (struct sockaddr *) &address_storage, &len);
+
+  if (r < 0) {
+    return ThrowException(ErrnoException(errno, "getsockname"));
+  }
+
+  Local<Object> info = Object::New();
+
+  if (address_storage.ss_family == AF_INET6) {
+    struct sockaddr_in6 *a = (struct sockaddr_in6*)&address_storage;
+
+    char ip[INET6_ADDRSTRLEN];
+    inet_ntop(AF_INET6, &(a->sin6_addr), ip, INET6_ADDRSTRLEN);
+
+    int port = ntohs(a->sin6_port);
+
+    info->Set(remote_address_symbol, String::New(ip));
+    info->Set(remote_port_symbol, Integer::New(port));
+  }
+
+  return scope.Close(info);
+}
+
 
 static Handle<Value> Listen(const Arguments& args) {
   HandleScope scope;
@@ -484,6 +517,78 @@ static Handle<Value> Read(const Arguments& args) {
   return scope.Close(Integer::New(bytes_read));
 }
 
+// bytesRead, receivedFd = t.recvMsg(fd, buffer, offset, length)
+static Handle<Value> RecvMsg(const Arguments& args) {
+  HandleScope scope;
+
+  if (args.Length() < 4) {
+    return ThrowException(Exception::TypeError(
+          String::New("Takes 4 parameters")));
+  }
+
+  FD_ARG(args[0])
+
+  if (!IsBuffer(args[1])) { 
+    return ThrowException(Exception::TypeError(
+          String::New("Second argument should be a buffer")));
+  }
+
+  struct buffer * buffer = BufferUnwrap(args[1]);
+
+  size_t off = args[2]->Int32Value();
+  if (buffer_p(buffer, off) == NULL) {
+    return ThrowException(Exception::Error(
+          String::New("Offset is out of bounds")));
+  }
+
+  size_t len = args[3]->Int32Value();
+  if (buffer_remaining(buffer, off) < len) {
+    return ThrowException(Exception::Error(
+          String::New("Length is extends beyond buffer")));
+  }
+
+  struct iovec iov[1];
+  struct msghdr msg;
+  int received_fd;
+  char control_msg[CMSG_SPACE(sizeof(received_fd))];
+  struct cmsghdr *cmsg;
+
+  // TODO: zero out control_msg ?
+
+  iov[0].iov_base = buffer_p(buffer, off);
+  iov[0].iov_len = buffer_remaining(buffer, off);
+  msg.msg_iov = iov;
+  msg.msg_iovlen = 1;
+  msg.msg_name = NULL;
+  msg.msg_namelen = 0;
+  /* Set up to receive a descriptor even if one isn't in the message */
+  msg.msg_control = (void *) control_msg;
+  msg.msg_controllen = CMSG_LEN(sizeof(received_fd));
+
+  ssize_t bytes_read = recvmsg(fd, &msg, 0);
+
+  if (bytes_read < 0) {
+    if (errno == EAGAIN || errno == EINTR) return Null();
+    return ThrowException(ErrnoException(errno, "recvMsg"));
+  }
+
+  // Return array of [bytesRead, fd] with fd == -1 if there was no FD
+  Local<Array> a = Array::New(2);
+  a->Set(Integer::New(0), Integer::New(bytes_read));
+
+  cmsg = CMSG_FIRSTHDR(&msg);
+  if (cmsg->cmsg_type == SCM_RIGHTS) {
+    received_fd = *(int *) CMSG_DATA(cmsg);
+  }
+  else {
+    received_fd = -1;
+  }
+
+  a->Set(Integer::New(1), Integer::New(received_fd));
+  return scope.Close(a);
+}
+
+
 //  var bytesWritten = t.write(fd, buffer, offset, length);
 //  returns null on EAGAIN or EINTR, raises an exception on all other errors
 static Handle<Value> Write(const Arguments& args) {
@@ -527,6 +632,60 @@ static Handle<Value> Write(const Arguments& args) {
   return scope.Close(Integer::New(written));
 }
 
+// var bytesWritten = t.sendFD(self.fd)
+//  returns null on EAGAIN or EINTR, raises an exception on all other errors
+static Handle<Value> SendFD(const Arguments& args) {
+  HandleScope scope;
+
+  if (args.Length() < 2) {
+    return ThrowException(Exception::TypeError(
+          String::New("Takes 2 parameters")));
+  }
+
+  FD_ARG(args[0])
+
+  // TODO: make sure fd is a unix domain socket?
+
+  if (!args[1]->IsInt32()) {
+    return ThrowException(Exception::TypeError(
+          String::New("FD to send is not an integer")));
+  }
+
+  int fd_to_send = args[1]->Int32Value();
+
+  struct msghdr msg;
+  struct iovec iov[1];
+  char control_msg[CMSG_SPACE(sizeof(fd_to_send))];
+  struct cmsghdr *cmsg;
+  char *dummy = "d"; // Need to send at least a byte of data in the message
+
+  iov[0].iov_base = dummy;
+  iov[0].iov_len = 1;
+  msg.msg_iov = iov;
+  msg.msg_iovlen = 1;
+  msg.msg_name = NULL;
+  msg.msg_namelen = 0;
+  msg.msg_flags = 0;
+  msg.msg_control = (void *) control_msg;
+  cmsg = CMSG_FIRSTHDR(&msg);
+  cmsg->cmsg_level = SOL_SOCKET;
+  cmsg->cmsg_type = SCM_RIGHTS;
+  cmsg->cmsg_len = CMSG_LEN(sizeof(fd_to_send));
+  *(int*) CMSG_DATA(cmsg) = fd_to_send;
+  msg.msg_controllen = cmsg->cmsg_len;
+
+  ssize_t written = sendmsg(fd, &msg, 0);
+
+  if (written < 0) {
+    if (errno == EAGAIN || errno == EINTR) return Null();
+    return ThrowException(ErrnoException(errno, "sendmsg"));
+  }
+
+  /* Note that the FD isn't explicitly closed here, this
+   * happens in the JS */
+
+  return scope.Close(Integer::New(written));
+}
 
 // Probably only works for Linux TCP sockets?
 // Returns the amount of data on the read queue.
@@ -744,6 +903,9 @@ void InitNet2(Handle<Object> target) {
   NODE_SET_METHOD(target, "write", Write);
   NODE_SET_METHOD(target, "read", Read);
 
+  NODE_SET_METHOD(target, "sendFD", SendFD);
+  NODE_SET_METHOD(target, "recvMsg", RecvMsg);
+
   NODE_SET_METHOD(target, "socket", Socket);
   NODE_SET_METHOD(target, "close", Close);
   NODE_SET_METHOD(target, "shutdown", Shutdown);
@@ -757,7 +919,8 @@ void InitNet2(Handle<Object> target) {
   NODE_SET_METHOD(target, "socketError", SocketError);
   NODE_SET_METHOD(target, "toRead", ToRead);
   NODE_SET_METHOD(target, "setNoDelay", SetNoDelay);
-  NODE_SET_METHOD(target, "getsocksame", GetSockName);
+  NODE_SET_METHOD(target, "getsockname", GetSockName);
+  NODE_SET_METHOD(target, "getpeername", GetPeerName);
   NODE_SET_METHOD(target, "getaddrinfo", GetAddrInfo);
   NODE_SET_METHOD(target, "needsLookup", NeedsLookup);
 

test/mjsunit/fixtures/net-fd-passing-receiver.js

@@ -0,0 +1,37 @@
+process.mixin(require("../common"));
+net = require("net");
+
+process.Buffer.prototype.toString = function () {
+  return this.utf8Slice(0, this.length);
+};
+
+
+path = process.ARGV[2];
+greeting = process.ARGV[3];
+
+receiver = net.createServer(function(socket) {
+  socket.addListener("fd", function(fd) {
+    var peerInfo = process.getpeername(fd);
+    peerInfo.fd = fd;
+    var passedSocket = new net.Socket(peerInfo);
+
+    passedSocket.addListener("eof", function() {
+      passedSocket.close();
+    });
+
+    passedSocket.addListener("data", function(data) {
+      passedSocket.send("[echo] " + data);
+    });
+    passedSocket.addListener("close", function() {
+      receiver.close();
+    });
+    passedSocket.send("[greeting] " + greeting);
+  });
+});
+
+/* To signal the test runne we're up and listening */
+receiver.addListener("listening", function() {
+  print("ready");
+});
+
+receiver.listen(path);

test/mjsunit/test-net-fd-passing.js

@@ -0,0 +1,67 @@
+process.mixin(require("./common"));
+net = require("net");
+
+process.Buffer.prototype.toString = function () {
+  return this.utf8Slice(0, this.length);
+};
+
+var tests_run = 0;
+
+function fdPassingTest(path, port) {
+  var greeting = "howdy";
+  var message = "beep toot";
+  var expectedData = ["[greeting] " + greeting, "[echo] " + message];
+
+  puts(fixturesDir);
+  var receiverArgs = [fixturesDir + "/net-fd-passing-receiver.js", path, greeting];
+  var receiver = process.createChildProcess(process.ARGV[0], receiverArgs);
+
+  var initializeSender = function() {
+    var fdHighway = new net.Socket();
+    fdHighway.connect(path);
+
+    var sender = net.createServer(function(socket) {
+      fdHighway.sendFD(socket);
+      socket.flush();
+      socket.forceClose(); // want to close() the fd, not shutdown()
+    });
+
+    sender.addListener("listening", function() {
+      var client = net.createConnection(port);
+
+      client.addListener("connect", function() {
+        client.send(message);
+      });
+
+      client.addListener("data", function(data) {
+        assert.equal(expectedData[0], data);
+        if (expectedData.length > 1) {
+          expectedData.shift();
+        }
+        else {
+          // time to shut down
+          fdHighway.close();
+          sender.close();
+          client.forceClose();
+        }
+      });
+    });
+
+    tests_run += 1;
+    sender.listen(port);
+  };
+
+  receiver.addListener("output", function(data) {
+    var initialized = false;
+    if ((! initialized) && (data == "ready")) {
+      initializeSender();
+      initialized = true;
+    }
+  });
+}
+
+fdPassingTest("/tmp/passing-socket-test", 31075);
+
+process.addListener("exit", function () {
+  assert.equal(1, tests_run);
+});