gistfile1.txt

    if (platform == "win") {
        libc = ctypes.open("Ws2_32.dll");
        var dnsapi = ctypes.open("Dnsapi.dll");
        var DNS_RECORD = new ctypes.StructType("DNS_RECORD");
        DNS_RECORD.define([{"pNext":DNS_RECORD.ptr}, {"pName":ctypes.char.ptr}, {"wType":ctypes.unsigned_short},
                           {"wDataLength":ctypes.unsigned_short}, {"DW":ctypes.unsigned_long}, {"dwTtl":ctypes.unsigned_long},
                           {"dwReserved":ctypes.unsigned_long}, {"pNameHost":ctypes.char.ptr}]);
        var DnsQuery = dnsapi.declare("DnsQuery_A", ctypes.winapi_abi, ctypes.int, ctypes.char.ptr, ctypes.unsigned_short,
                                      ctypes.unsigned_long, ctypes.voidptr_t, DNS_RECORD.ptr, ctypes.voidptr_t);
        var DnsRecordListFree = dnsapi.declare("DnsRecordListFree", ctypes.winapi_abi, ctypes.void_t, DNS_RECORD.ptr,
                                               ctypes.int);
        var record = new DNS_RECORD();
        var getIPForLookup = function(ip) {
            if (ip.indexOf(".") != -1) {
                // IPv4
                x = ip.split(".").reverse().join(".")+".in-addr.arpa";
            } else {
                if (ip.indexOf("%") != -1) ip = ip.substr(0, ip.indexOf("%"));
                // IPv6
                var parts = ip.split(":");
                x = "ip6.arpa"
                for (var i = 0; i < parts.length; i++) {
                    var part = parts[i];
                    for (var j = 0; j < (part.length == 0 ? 4*(9-parts.length) : 4-part.length); j++) x = "0." + x;
                    for (var j = 0; j < part.length; j++) x = part[j] + "." + x;
                }
            }
            return x;
        }
        var reverseLookup = function(ip) {
            var status = DnsQuery(getIPForLookup(ip), 12 /*DNS_TYPE_PTR*/, 32 /*DNS_QUERY_NO_LOCAL_NAME*/, null, record.address(), null);
            if (status != 0 || record.pNext.isNull()) return null;
            var retval = record.pNext.contents.pNameHost.readString();
            DnsRecordListFree(record.pNext, 1);
            return retval;
        };
    } else if (platform == "mac") {
        libc = ctypes.open("libc.dylib");
    } else {
        var possibleLibcs = [
            "libc.so.6",
            "libc.so.6.1",
            "libc.so"
        ];
        for(var i = 0; i < possibleLibcs.length; i++) {
            try {
                libc = ctypes.open(possibleLibcs[i]);
                break;
            } catch(e) {}
        }
    }

    var sockaddr = new ctypes.StructType("sockaddr");
    var addrinfo = new ctypes.StructType("arrinfo");
    addrinfo.define([{"ai_flags":ctypes.int}, {"ai_family":ctypes.int}, {"ai_socktype":ctypes.int},
                     {"ai_protocol":ctypes.int}, {"ai_addrlen":ctypes.int}, {"ai_canonname":ctypes.char.ptr},
                     {"ai_addr":sockaddr.ptr}, {"ai_next":addrinfo.ptr}]);
    var gethostname = libc.declare("gethostname", ctypes.default_abi, ctypes.int, ctypes.char.ptr, ctypes.size_t);
    var getaddrinfo = libc.declare("getaddrinfo", ctypes.default_abi, ctypes.int, ctypes.char.ptr, ctypes.char.ptr,
                                   addrinfo.ptr, addrinfo.ptr.ptr);
    var freeaddrinfo = libc.declare("freeaddrinfo", ctypes.default_abi, ctypes.void_t, addrinfo.ptr);
    var getnameinfo = libc.declare("getnameinfo", ctypes.default_abi, ctypes.int, sockaddr.ptr, ctypes.int,
                                   ctypes.char.ptr, ctypes.int, ctypes.char.ptr, ctypes.int, ctypes.int);

    var buf = new new ctypes.ArrayType(ctypes.char, 1025);
    var status = gethostname(buf, 1025);
    if (status != 0) throw new Error("could not get hostname: "+status);

    var hosts = [];
    var hints = new addrinfo();
    if (platform != "win") hints.ai_flags = 2;
    var out = new addrinfo.ptr();
    status = getaddrinfo(buf, null, hints.address(), out.address());
    if (status != 0) throw new Error("could not get addrinfo: "+status);
    var rec = out;
    try {
        if (platform == "win") {
            while (!rec.isNull()) {
                status = getnameinfo(rec.contents.ai_addr, rec.contents.ai_addrlen, buf, 1025, null, 0, 2);
                if (status != 0) throw new Error("could not get IP address: "+status);
                var host = reverseLookup(buf.readString());
                if (host) hosts.push(host);
                rec = rec.contents.ai_next;
            }
        } else {
            // Not perfect, but need to figure out the right API to do a
            // proper query
            while (!rec.isNull()) {
                if (!rec.contents.ai_canonname.isNull()) hosts.push(rec.contents.ai_canonname.readString());
                rec = rec.contents.ai_next;
            }
        }
    } finally {
        freeaddrinfo(out);
    }