How to setsockopt under node.js? - node.js

Question

Is there a setsockopt/getsockopt-like socket options manipulation functionality in node.js?

Answer 1

I'm expanding on the comment left by socketpair which shows getsockopt. You can accomplish this by using ffi and ref. I've reformatted this to allow it to be easily manipulated.
I edited my comment because I had to make some changes to make the code work on both Linux and Win32. I had to create a node library for Windows to get the socket handle and pass it to setsockopt. Be aware that Linux and Windows may have different values for socket options
Edit: Here's a cleaned up piece of of production code I'm using:
var net = require("net");
var ffi = require("ffi");
var ref = require("ref");
var getSocketHandleAddress;
var SOL_SOCKET = 0x1;
var SO_OOBINLINE = 0xA;
var _setsockopt;
if (process.platform == "win32") {
SOL_SOCKET = 0xffff;
SO_OOBINLINE = 0x0100;
}
var setSocketOption = function (handle, level, option, value) {
if (!_setsockopt) {
var library;
var paramTypes;
if (process.platform === "win32") {
library = "ws2_32.dll";
paramTypes = [
ref.types.int,
ref.types.int,
ref.types.int,
ref.refType(ref.types.void),
ref.types.int
];
} else {
paramTypes = [
ref.types.int,
ref.types.int,
ref.types.int,
ref.refType(ref.types.void),
ref.refType(ref.types.int)
];
}
var lib = new ffi.DynamicLibrary(library);
_setsockopt = ffi.ForeignFunction(
lib.get("setsockopt"),
ref.types.int,
paramTypes);
}
var refType;
var length;
if (typeof value === "boolean") {
refType = ref.types.bool;
} else {
refType = ref.types.int;
}
if (process.platform !== "win32") {
return _setsockopt(
handle.fd,
level,
option,
ref.alloc(refType, value),
ref.alloc(ref.types.int, refType.size)
);
}
if (!getSocketHandleAddress) {
getSocketHandleAddress = require("getsockethandleaddress");
}
return _setsockopt(
getSocketHandleAddress.getAddress(handle),
level,
option,
ref.alloc(refType, value),
refType.size
);
};
var tcpserver = net.createServer(function (socket) {
var ret = setSocketOption(socket._handle, SOL_SOCKET, SO_OOBINLINE, true);
if (ret !== 0) {
console.error("OOB Inline socket option failed: " + ret);
}
});

Answer 2

This is my getsockopt:
var ffi = require('ffi');
var net = require('net');
var StructType = require('ref-struct');
var ref = require('ref');
var current = ffi.Library(null, {
'getsockopt': [ 'int', [ 'int', 'int', 'int', 'pointer', 'pointer']],
'ntohs': ['uint16', ['uint16']],
// const char *inet_ntop(int af, const void *src, char *dst, socklen_t size);
});
var SOL_IP = 0;
var SO_ORIGINAL_DST = 80;
var AF_INET = 2;
var sockaddr_in = StructType([
['int16', 'sin_family'],
['uint16', 'sin_port'],
['uint32', 'sin_addr'],
['uint32', 'trash1'],
['uint32', 'trash2'],
]);
function get_original_dst(client) {
var dst = new sockaddr_in;
var dstlen = ref.alloc(ref.types.int, sockaddr_in.size);
var r = current.getsockopt(client._handle.fd, SOL_IP, SO_ORIGINAL_DST, dst.ref(), dstlen);
if (r === -1)
throw new Error("getsockopt(SO_ORIGINAL_DST) error");
if (dst.sin_family !== AF_INET)
throw new Error("getsockopt(SO_ORIGINAL_DST) returns unknown family: " + dst.sin_family );
// TODO: inet_ntop. inet_ntoa is _UNSAFE_
var ipaddr = dst.ref(); ipaddr = ipaddr[4] + "." + ipaddr[5] + "." + ipaddr[6] + "." + ipaddr[7];
return [ipaddr, current.ntohs(dst.sin_port)];
}
module.exports.get_original_dst = get_original_dst;

Answer 3

Kind of late but here is a pacakge on npm https://www.npmjs.com/package/net-keepalive
Provides high-level access to socket options like TCP_KEEPIDLE, TCP_KEEPINTVL, TCP_KEEPCNT
var Net = require('net')
, NetKeepAlive = require('net-keepalive')
;
// Create a TCP Server
var srv = Net.createServer(function(s){>
console.log('Connected %j', s.address())
// Doesn't matter what it does
s.pipe(s)
});
// Start on some port
srv.listen(1337, function(){
console.log('Listening on %j', srv.address())
});
// Connect to that server
var s = Net.createConnection({port:1337}, function(){
console.log('Connected to %j', s.address())
//IMPORTANT: KeepAlive must be enabled for this to work
s.setKeepAlive(true, 1000)
// Set TCP_KEEPINTVL for this specific socket
NetKeepAlive.setKeepAliveInterval(s, 1000)
// and TCP_KEEPCNT
NetKeepAlive.setKeepAliveProbes(s, 1)
});