Implement datagram sockets

- Adds new dgram module, for all data-gram type transports
- Supports both UDP client and servers
- Supports Unix Daemon sockets in DGRAM mode too (think syslog)
- Uses a shared Buffer and slices that as needed to be reasonably
  performant.
- One supplied test program so far, test-dgram-pingpong
- Passes test cases on osx 10.6 and ubuntu 9.10u

lib/dgram.js

@@ -0,0 +1,184 @@
+var sys = require("sys");
+var fs = require("fs");
+var events = require("events");
+var dns = require('dns');
+
+var Buffer = require('buffer').Buffer;
+var IOWatcher   = process.IOWatcher;
+var binding     = process.binding('net');
+var socket      = binding.socket;
+var bind        = binding.bind;
+var recvfrom    = binding.recvfrom;
+var sendto      = binding.sendto;
+var close       = binding.close;
+var ENOENT      = binding.ENOENT;
+
+function isPort (x) { return parseInt(x) >= 0; }
+var pool = null;
+
+function getPool() {
+  /* TODO: this effectively limits you to 8kb maximum packet sizes */
+  var minPoolAvail = 1024 * 8;
+
+  var poolSize = 1024 * 64;
+
+  if (pool === null || (pool.used + minPoolAvail  > pool.length)) {
+    pool = new Buffer(poolSize);
+    pool.used = 0;
+  }
+
+  return pool;
+}
+
+function Socket (listener) {
+  events.EventEmitter.call(this);
+  var self = this;
+
+  if (listener) {
+    self.addListener('message', listener);
+  }
+
+  self.watcher = new IOWatcher();
+  self.watcher.host = self;
+  self.watcher.callback = function () {
+    while (self.fd) {
+      var p = getPool();
+      var rinfo = recvfrom(self.fd, p, p.used, p.length - p.used, 0);
+
+      if (!rinfo) return;
+
+      self.emit('message', p.slice(p.used, p.used + rinfo.size), rinfo);
+
+      p.used += rinfo.size;
+    }
+  };
+}
+
+sys.inherits(Socket, events.EventEmitter);
+exports.Socket = Socket;
+
+exports.createSocket = function (listener) {
+  return new Socket(listener);
+};
+
+Socket.prototype.bind = function () {
+  var self = this;
+  if (self.fd) throw new Error('Server already opened');
+
+  if (!isPort(arguments[0])) {
+    /* TODO: unix path dgram */
+    self.fd = socket('unix_dgram');
+    self.type = 'unix_dgram';
+    var path = arguments[0];
+    self.path = path;
+    // unlink sockfile if it exists
+    fs.stat(path, function (err, r) {
+      if (err) {
+        if (err.errno == ENOENT) {
+          bind(self.fd, path);
+          process.nextTick(function() {
+            self._startWatcher();
+          });
+        } else {
+          throw r;
+        }
+      } else {
+        if (!r.isFile()) {
+          throw new Error("Non-file exists at  " + path);
+        } else {
+          fs.unlink(path, function (err) {
+            if (err) {
+              throw err;
+            } else {
+              bind(self.fd, path);
+              process.nextTick(function() {
+                self._startWatcher();
+              });
+            }
+          });
+        }
+      }
+    });
+  } else if (!arguments[1]) {
+    // Don't bind(). OS will assign a port with INADDR_ANY.
+    // The port can be found with server.address()
+    self.type = 'udp4';
+    self.fd = socket(self.type);
+    bind(self.fd, arguments[0]);
+    process.nextTick(function() {
+      self._startWatcher();
+    });
+  } else {
+    // the first argument is the port, the second an IP
+    var port = arguments[0];
+    dns.lookup(arguments[1], function (err, ip, addressType) {
+      if (err) {
+        self.emit('error', err);
+      } else {
+        self.type = addressType == 4 ? 'udp4' : 'udp6';
+        self.fd = socket(self.type);
+        bind(self.fd, port, ip);
+        process.nextTick(function() {
+          self._startWatcher();
+        });
+      }
+    });
+  }
+};
+
+Socket.prototype._startWatcher = function () {
+  this.watcher.set(this.fd, true, false);
+  this.watcher.start();
+  this.emit("listening");
+};
+
+Socket.prototype.address = function () {
+  return getsockname(this.fd);
+};
+
+Socket.prototype.send = function(port, addr, buffer, offset, length) {
+  var self = this;
+
+  if (!isPort(arguments[0])) {
+    if (!self.fd) {
+      self.type = 'unix_dgram';
+      self.fd = socket(self.type);
+    }
+    sendto(self.fd, buffer, offset, length, 0, port, addr);
+  }
+  else {
+    dns.lookup(arguments[1], function (err, ip, addressType) {
+      if (err) {
+        self.emit('error', err);
+      } else {
+        if (!self.fd) {
+          self.type = addressType == 4 ? 'udp4' : 'udp6';
+          self.fd = socket(self.type);
+          process.nextTick(function() {
+            self._startWatcher();
+          });
+        }
+        sendto(self.fd, buffer, offset, length, 0, port, ip);
+      }
+    });
+  }
+};
+
+Socket.prototype.close = function () {
+  var self = this;
+
+  if (!self.fd) throw new Error('Not running');
+
+  self.watcher.stop();
+
+  close(self.fd);
+  self.fd = null;
+
+  if (self.type === "unix_dgram") {
+    fs.unlink(self.path, function () {
+      self.emit("close");
+    });
+  } else {
+    self.emit("close");
+  }
+};

src/node.cc

@@ -1845,6 +1845,7 @@ static Handle<Value> Binding(const Arguments& args) {
       exports->Set(String::New("assert"),       String::New(native_assert));
       exports->Set(String::New("buffer"),       String::New(native_buffer));
       exports->Set(String::New("child_process"),String::New(native_child_process));
+      exports->Set(String::New("dgram"),        String::New(native_dgram));
       exports->Set(String::New("dns"),          String::New(native_dns));
       exports->Set(String::New("events"),       String::New(native_events));
       exports->Set(String::New("file"),         String::New(native_file));

src/node_net.cc

@@ -42,6 +42,7 @@ static Persistent<String> errno_symbol;
 static Persistent<String> syscall_symbol;
 
 static Persistent<String> fd_symbol;
+static Persistent<String> size_symbol;
 static Persistent<String> address_symbol;
 static Persistent<String> port_symbol;
 static Persistent<String> type_symbol;
@@ -147,7 +148,16 @@ static Handle<Value> Socket(const Arguments& args) {
     } else if (0 == strcasecmp(*t, "UNIX")) {
       domain = PF_UNIX;
       type = SOCK_STREAM;
+    } else if (0 == strcasecmp(*t, "UNIX_DGRAM")) {
+      domain = PF_UNIX;
+      type = SOCK_DGRAM;
     } else if (0 == strcasecmp(*t, "UDP")) {
+      domain = PF_INET;
+      type = SOCK_DGRAM;
+    } else if (0 == strcasecmp(*t, "UDP4")) {
+      domain = PF_INET;
+      type = SOCK_DGRAM;
+    } else if (0 == strcasecmp(*t, "UDP6")) {
       domain = PF_INET6;
       type = SOCK_DGRAM;
     } else {
@@ -520,6 +530,63 @@ static Handle<Value> Read(const Arguments& args) {
   return scope.Close(Integer::New(bytes_read));
 }
 
+//  var info = t.recvfrom(fd, buffer, offset, length, flags);
+//    info.size // bytes read
+//    info.port // from port
+//    info.address // from address
+//  returns null on EAGAIN or EINTR, raises an exception on all other errors
+//  returns object otherwise
+static Handle<Value> RecvFrom(const Arguments& args) {
+  HandleScope scope;
+
+  if (args.Length() < 5) {
+    return ThrowException(Exception::TypeError(
+          String::New("Takes 5 parameters")));
+  }
+
+  FD_ARG(args[0])
+
+  if (!Buffer::HasInstance(args[1])) {
+    return ThrowException(Exception::TypeError(
+          String::New("Second argument should be a buffer")));
+  }
+
+  Buffer * buffer = ObjectWrap::Unwrap<Buffer>(args[1]->ToObject());
+
+  size_t off = args[2]->Int32Value();
+  if (off >= buffer->length()) {
+    return ThrowException(Exception::Error(
+          String::New("Offset is out of bounds")));
+  }
+
+  size_t len = args[3]->Int32Value();
+  if (off + len > buffer->length()) {
+    return ThrowException(Exception::Error(
+          String::New("Length is extends beyond buffer")));
+  }
+
+  int flags = args[4]->Int32Value();
+
+  struct sockaddr_storage address_storage;
+  socklen_t addrlen = sizeof(struct sockaddr_storage);
+
+  ssize_t bytes_read = recvfrom(fd, (char*)buffer->data() + off, len, flags, 
+                                (struct sockaddr*) &address_storage, &addrlen);
+
+  if (bytes_read < 0) {
+    if (errno == EAGAIN || errno == EINTR) return Null();
+    return ThrowException(ErrnoException(errno, "read"));
+  }
+
+  Local<Object> info = Object::New();
+
+  info->Set(size_symbol, Integer::New(bytes_read));
+
+  ADDRESS_TO_JS(info, address_storage);
+
+  return scope.Close(info);
+}
+
 
 // bytesRead = t.recvMsg(fd, buffer, offset, length)
 // if (recvMsg.fd) {
@@ -780,6 +847,93 @@ static Handle<Value> SendMsg(const Arguments& args) {
   return scope.Close(Integer::New(written));
 }
 
+// var bytes = sendto(fd, buf, off, len, flags, destination port, desitnation address);
+//
+// Write a buffer with optional offset and length to the given file
+// descriptor. Note that we refuse to send 0 bytes.
+//
+// The 'fd' parameter is a numerical file descriptor, or the undefined value
+// to send none.
+//
+// The 'flags' parameter is a number representing a bitmask of MSG_* values.
+// This is passed directly to sendmsg().
+//
+// The destination port can either be an int port, or a path.
+//
+// Returns null on EAGAIN or EINTR, raises an exception on all other errors
+static Handle<Value> SendTo(const Arguments& args) {
+  HandleScope scope;
+
+  if (args.Length() < 5) {
+    return ThrowException(Exception::TypeError(
+          String::New("Takes 5 or 6 parameters")));
+  }
+
+  // The first argument should be a file descriptor
+  FD_ARG(args[0])
+
+  // Grab the actul data to be written
+  if (!Buffer::HasInstance(args[1])) {
+    return ThrowException(Exception::TypeError(
+      String::New("Expected either a string or a buffer")));
+  }
+
+  Buffer *buf = ObjectWrap::Unwrap<Buffer>(args[1]->ToObject());
+
+  size_t offset = 0;
+  if (args.Length() >= 3 && !args[2]->IsUndefined()) {
+    if (!args[2]->IsUint32()) {
+      return ThrowException(Exception::TypeError(
+        String::New("Expected unsigned integer for offset")));
+    }
+
+    offset = args[2]->Uint32Value();
+    if (offset >= buf->length()) {
+      return ThrowException(Exception::Error(
+        String::New("Offset into buffer too large")));
+    }
+  }
+
+  size_t length = buf->length() - offset;
+  if (args.Length() >= 4 && !args[3]->IsUndefined()) {
+    if (!args[3]->IsUint32()) {
+      return ThrowException(Exception::TypeError(
+        String::New("Expected unsigned integer for length")));
+    }
+
+    length = args[3]->Uint32Value();
+    if (offset + length > buf->length()) {
+      return ThrowException(Exception::Error(
+        String::New("offset + length beyond buffer length")));
+    }
+  }
+
+  int flags = 0;
+  if (args.Length() >= 5 && !args[4]->IsUndefined()) {
+    if (!args[4]->IsUint32()) {
+      return ThrowException(Exception::TypeError(
+        String::New("Expected unsigned integer for a flags argument")));
+    }
+
+    flags = args[4]->Uint32Value();
+  }
+
+  Handle<Value> error = ParseAddressArgs(args[5], args[6], false);
+  if (!error.IsEmpty()) return ThrowException(error);
+
+  ssize_t written = sendto(fd, buf->data() + offset, length, flags, addr, addrlen);
+
+  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.
@@ -891,6 +1045,8 @@ void InitNet(Handle<Object> target) {
   NODE_SET_METHOD(target, "read", Read);
 
   NODE_SET_METHOD(target, "sendMsg", SendMsg);
+  NODE_SET_METHOD(target, "recvfrom", RecvFrom);
+  NODE_SET_METHOD(target, "sendto", SendTo);
 
   recv_msg_template =
       Persistent<FunctionTemplate>::New(FunctionTemplate::New(RecvMsg));
@@ -927,6 +1083,7 @@ void InitNet(Handle<Object> target) {
   errno_symbol          = NODE_PSYMBOL("errno");
   syscall_symbol        = NODE_PSYMBOL("syscall");
   fd_symbol             = NODE_PSYMBOL("fd");
+  size_symbol           = NODE_PSYMBOL("size");
   address_symbol        = NODE_PSYMBOL("address");
   port_symbol           = NODE_PSYMBOL("port");
 }