Craig Condon
382 lines
18 KiB
JSON
382 lines
18 KiB
JSON
{
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"source": "doc/api/dgram.markdown",
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"modules": [
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{
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"textRaw": "UDP / Datagram Sockets",
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"name": "dgram",
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"stability": 3,
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"stabilityText": "Stable",
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"desc": "<p>Datagram sockets are available through <code>require('dgram')</code>.\n\n</p>\n",
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"methods": [
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{
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"textRaw": "dgram.createSocket(type, [callback])",
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"type": "method",
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"name": "createSocket",
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"signatures": [
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{
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"return": {
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"textRaw": "Returns: Socket object ",
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"name": "return",
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"desc": "Socket object"
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},
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"params": [
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{
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"textRaw": "`type` String. Either 'udp4' or 'udp6' ",
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"name": "type",
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"desc": "String. Either 'udp4' or 'udp6'"
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},
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{
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"textRaw": "`callback` Function. Attached as a listener to `message` events. Optional ",
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"name": "callback",
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"optional": true,
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"desc": "Function. Attached as a listener to `message` events."
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}
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]
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},
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{
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"params": [
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{
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"name": "type"
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},
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{
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"name": "callback",
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"optional": true
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}
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]
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}
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],
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"desc": "<p>Creates a datagram Socket of the specified types. Valid types are <code>udp4</code>\nand <code>udp6</code>.\n\n</p>\n<p>Takes an optional callback which is added as a listener for <code>message</code> events.\n\n</p>\n<p>Call <code>socket.bind</code> if you want to receive datagrams. <code>socket.bind()</code> will bind\nto the "all interfaces" address on a random port (it does the right thing for\nboth <code>udp4</code> and <code>udp6</code> sockets). You can then retrieve the address and port\nwith <code>socket.address().address</code> and <code>socket.address().port</code>.\n\n</p>\n"
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}
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],
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"classes": [
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{
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"textRaw": "Class: Socket",
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"type": "class",
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"name": "Socket",
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"desc": "<p>The dgram Socket class encapsulates the datagram functionality. It\nshould be created via <code>dgram.createSocket(type, [callback])</code>.\n\n</p>\n",
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"events": [
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{
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"textRaw": "Event: 'message'",
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"type": "event",
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"name": "message",
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"params": [],
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"desc": "<p>Emitted when a new datagram is available on a socket. <code>msg</code> is a <code>Buffer</code> and <code>rinfo</code> is\nan object with the sender's address information and the number of bytes in the datagram.\n\n</p>\n"
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},
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{
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"textRaw": "Event: 'listening'",
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"type": "event",
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"name": "listening",
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"desc": "<p>Emitted when a socket starts listening for datagrams. This happens as soon as UDP sockets\nare created.\n\n</p>\n",
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"params": []
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},
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{
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"textRaw": "Event: 'close'",
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"type": "event",
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"name": "close",
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"desc": "<p>Emitted when a socket is closed with <code>close()</code>. No new <code>message</code> events will be emitted\non this socket.\n\n</p>\n",
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"params": []
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},
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{
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"textRaw": "Event: 'error'",
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"type": "event",
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"name": "error",
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"params": [],
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"desc": "<p>Emitted when an error occurs.\n\n</p>\n"
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}
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],
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"methods": [
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{
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"textRaw": "dgram.send(buf, offset, length, port, address, [callback])",
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"type": "method",
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"name": "send",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`buf` Buffer object. Message to be sent ",
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"name": "buf",
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"desc": "Buffer object. Message to be sent"
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},
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{
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"textRaw": "`offset` Integer. Offset in the buffer where the message starts. ",
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"name": "offset",
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"desc": "Integer. Offset in the buffer where the message starts."
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},
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{
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"textRaw": "`length` Integer. Number of bytes in the message. ",
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"name": "length",
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"desc": "Integer. Number of bytes in the message."
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},
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{
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"textRaw": "`port` Integer. destination port ",
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"name": "port",
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"desc": "Integer. destination port"
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},
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{
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"textRaw": "`address` String. destination IP ",
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"name": "address",
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"desc": "String. destination IP"
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},
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{
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"textRaw": "`callback` Function. Callback when message is done being delivered. Optional. ",
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"name": "callback",
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"desc": "Function. Callback when message is done being delivered. Optional.",
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"optional": true
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}
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]
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},
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{
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"params": [
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{
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"name": "buf"
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},
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{
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"name": "offset"
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},
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{
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"name": "length"
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},
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{
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"name": "port"
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},
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{
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"name": "address"
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},
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{
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"name": "callback",
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"optional": true
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}
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]
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}
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],
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"desc": "<p>For UDP sockets, the destination port and IP address must be specified. A string\nmay be supplied for the <code>address</code> parameter, and it will be resolved with DNS. An\noptional callback may be specified to detect any DNS errors and when <code>buf</code> may be\nre-used. Note that DNS lookups will delay the time that a send takes place, at\nleast until the next tick. The only way to know for sure that a send has taken place\nis to use the callback.\n\n</p>\n<p>If the socket has not been previously bound with a call to <code>bind</code>, it's\nassigned a random port number and bound to the "all interfaces" address\n(0.0.0.0 for <code>udp4</code> sockets, ::0 for <code>udp6</code> sockets).\n\n</p>\n<p>Example of sending a UDP packet to a random port on <code>localhost</code>;\n\n</p>\n<pre><code>var dgram = require('dgram');\nvar message = new Buffer("Some bytes");\nvar client = dgram.createSocket("udp4");\nclient.send(message, 0, message.length, 41234, "localhost", function(err, bytes) {\n client.close();\n});</code></pre>\n<p><strong>A Note about UDP datagram size</strong>\n\n</p>\n<p>The maximum size of an <code>IPv4/v6</code> datagram depends on the <code>MTU</code> (<em>Maximum Transmission Unit</em>)\nand on the <code>Payload Length</code> field size.\n\n</p>\n<ul>\n<li><p>The <code>Payload Length</code> field is <code>16 bits</code> wide, which means that a normal payload\ncannot be larger than 64K octets including internet header and data\n(65,507 bytes = 65,535 − 8 bytes UDP header − 20 bytes IP header);\nthis is generally true for loopback interfaces, but such long datagrams\nare impractical for most hosts and networks.</p>\n</li>\n<li><p>The <code>MTU</code> is the largest size a given link layer technology can support for datagrams.\nFor any link, <code>IPv4</code> mandates a minimum <code>MTU</code> of <code>68</code> octets, while the recommended <code>MTU</code>\nfor IPv4 is <code>576</code> (typically recommended as the <code>MTU</code> for dial-up type applications),\nwhether they arrive whole or in fragments.</p>\n<p>For <code>IPv6</code>, the minimum <code>MTU</code> is <code>1280</code> octets, however, the mandatory minimum\nfragment reassembly buffer size is <code>1500</code> octets.\nThe value of <code>68</code> octets is very small, since most current link layer technologies have\na minimum <code>MTU</code> of <code>1500</code> (like Ethernet).</p>\n</li>\n</ul>\n<p>Note that it's impossible to know in advance the MTU of each link through which\na packet might travel, and that generally sending a datagram greater than\nthe (receiver) <code>MTU</code> won't work (the packet gets silently dropped, without\ninforming the source that the data did not reach its intended recipient).\n\n</p>\n"
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},
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{
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"textRaw": "dgram.bind(port, [address])",
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"type": "method",
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"name": "bind",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`port` Integer ",
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"name": "port",
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"desc": "Integer"
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},
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{
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"textRaw": "`address` String, Optional ",
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"name": "address",
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"optional": true,
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"desc": "String"
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}
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]
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},
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{
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"params": [
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{
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"name": "port"
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},
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{
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"name": "address",
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"optional": true
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}
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]
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}
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],
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"desc": "<p>For UDP sockets, listen for datagrams on a named <code>port</code> and optional <code>address</code>. If\n<code>address</code> is not specified, the OS will try to listen on all addresses.\n\n</p>\n<p>Example of a UDP server listening on port 41234:\n\n</p>\n<pre><code>var dgram = require("dgram");\n\nvar server = dgram.createSocket("udp4");\n\nserver.on("message", function (msg, rinfo) {\n console.log("server got: " + msg + " from " +\n rinfo.address + ":" + rinfo.port);\n});\n\nserver.on("listening", function () {\n var address = server.address();\n console.log("server listening " +\n address.address + ":" + address.port);\n});\n\nserver.bind(41234);\n// server listening 0.0.0.0:41234</code></pre>\n"
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},
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{
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"textRaw": "dgram.close()",
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"type": "method",
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"name": "close",
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"desc": "<p>Close the underlying socket and stop listening for data on it.\n\n</p>\n",
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"signatures": [
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{
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"params": []
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}
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]
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},
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{
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"textRaw": "dgram.address()",
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"type": "method",
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"name": "address",
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"desc": "<p>Returns an object containing the address information for a socket. For UDP sockets,\nthis object will contain <code>address</code> , <code>family</code> and <code>port</code>.\n\n</p>\n",
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"signatures": [
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{
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"params": []
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}
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]
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},
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{
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"textRaw": "dgram.setBroadcast(flag)",
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"type": "method",
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"name": "setBroadcast",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`flag` Boolean ",
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"name": "flag",
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"desc": "Boolean"
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}
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]
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},
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{
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"params": [
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{
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"name": "flag"
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}
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]
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}
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],
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"desc": "<p>Sets or clears the <code>SO_BROADCAST</code> socket option. When this option is set, UDP packets\nmay be sent to a local interface's broadcast address.\n\n</p>\n"
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},
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{
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"textRaw": "dgram.setTTL(ttl)",
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"type": "method",
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"name": "setTTL",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`ttl` Integer ",
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"name": "ttl",
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"desc": "Integer"
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}
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]
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},
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{
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"params": [
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{
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"name": "ttl"
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}
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]
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}
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],
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"desc": "<p>Sets the <code>IP_TTL</code> socket option. TTL stands for "Time to Live," but in this context it\nspecifies the number of IP hops that a packet is allowed to go through. Each router or\ngateway that forwards a packet decrements the TTL. If the TTL is decremented to 0 by a\nrouter, it will not be forwarded. Changing TTL values is typically done for network\nprobes or when multicasting.\n\n</p>\n<p>The argument to <code>setTTL()</code> is a number of hops between 1 and 255. The default on most\nsystems is 64.\n\n</p>\n"
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},
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{
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"textRaw": "dgram.setMulticastTTL(ttl)",
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"type": "method",
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"name": "setMulticastTTL",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`ttl` Integer ",
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"name": "ttl",
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"desc": "Integer"
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}
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]
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},
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{
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"params": [
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{
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"name": "ttl"
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}
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]
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}
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],
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"desc": "<p>Sets the <code>IP_MULTICAST_TTL</code> socket option. TTL stands for "Time to Live," but in this\ncontext it specifies the number of IP hops that a packet is allowed to go through,\nspecifically for multicast traffic. Each router or gateway that forwards a packet\ndecrements the TTL. If the TTL is decremented to 0 by a router, it will not be forwarded.\n\n</p>\n<p>The argument to <code>setMulticastTTL()</code> is a number of hops between 0 and 255. The default on most\nsystems is 1.\n\n</p>\n"
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},
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{
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"textRaw": "dgram.setMulticastLoopback(flag)",
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"type": "method",
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"name": "setMulticastLoopback",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`flag` Boolean ",
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"name": "flag",
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"desc": "Boolean"
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}
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]
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},
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{
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"params": [
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{
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"name": "flag"
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}
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]
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}
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],
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"desc": "<p>Sets or clears the <code>IP_MULTICAST_LOOP</code> socket option. When this option is set, multicast\npackets will also be received on the local interface.\n\n</p>\n"
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},
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{
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"textRaw": "dgram.addMembership(multicastAddress, [multicastInterface])",
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"type": "method",
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"name": "addMembership",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`multicastAddress` String ",
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"name": "multicastAddress",
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"desc": "String"
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},
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{
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"textRaw": "`multicastInterface` String, Optional ",
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"name": "multicastInterface",
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"optional": true,
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"desc": "String"
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}
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]
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},
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{
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"params": [
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{
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"name": "multicastAddress"
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},
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{
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"name": "multicastInterface",
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"optional": true
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}
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]
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}
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],
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"desc": "<p>Tells the kernel to join a multicast group with <code>IP_ADD_MEMBERSHIP</code> socket option.\n\n</p>\n<p>If <code>multicastInterface</code> is not specified, the OS will try to add membership to all valid\ninterfaces.\n\n</p>\n"
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},
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{
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"textRaw": "dgram.dropMembership(multicastAddress, [multicastInterface])",
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"type": "method",
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"name": "dropMembership",
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"signatures": [
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{
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"params": [
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{
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"textRaw": "`multicastAddress` String ",
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"name": "multicastAddress",
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"desc": "String"
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},
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{
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"textRaw": "`multicastInterface` String, Optional ",
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"name": "multicastInterface",
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"optional": true,
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"desc": "String"
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}
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]
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},
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{
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"params": [
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{
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"name": "multicastAddress"
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},
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{
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"name": "multicastInterface",
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"optional": true
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}
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]
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}
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],
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"desc": "<p>Opposite of <code>addMembership</code> - tells the kernel to leave a multicast group with\n<code>IP_DROP_MEMBERSHIP</code> socket option. This is automatically called by the kernel\nwhen the socket is closed or process terminates, so most apps will never need to call\nthis.\n\n</p>\n<p>If <code>multicastInterface</code> is not specified, the OS will try to drop membership to all valid\ninterfaces.\n</p>\n"
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}
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]
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}
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],
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"type": "module",
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"displayName": "dgram"
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}
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]
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}
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