node-gobgp-monitor.js

'use strict';

const readline = require("readline");
const fs = require("fs");
const {spawn} = require("child_process");

//<flag 2byte><timestamp 4><addr 4><mask 4><asn 4>
const packEvent = ev => {
  const buf = Buffer.alloc(18, 0);
  const timestamp = +new Date/1000|0;

  if(ev.withdrawal) {
    buf.writeUInt16BE(0x1, 0); // 0000 0000 0000 0001
  }

  buf.writeUInt32BE(timestamp, 2);

  const cidr = ev.nlri.prefix.split("/");
  cidr[0].split(".").forEach((a, i) => {
    buf.writeUInt8(parseInt(a, 10), 6 + i);
  });

  // powwwwwwwwwwwwwwwer!!!!!!!!!
  const subnet = (
    new Array(parseInt(cidr[1], 10) + 1).join("1")
    + new Array(32).join("0")
  ).slice(0, 32);

  for(let i = 0;i < 4;i++) {
    const mask = parseInt(subnet.slice(8*i, 8*(i+1)), 2);
    buf.writeUInt8(mask, 10 + i);
  }

  ev.attrs.forEach(attr => {
    if(attr.type === 2 && attr.as_paths) {
      const asn = parseInt(attr.as_paths[0].asns.slice(-1)[0], 10);
      buf.writeUInt32BE(asn, 14);
    }
  });

  return buf;
};


let counter = 0;

const ws = fs.createWriteStream(`${+new Date}.data`);

const rl = readline.createInterface({
  input: spawn("gobgp", ["monitor", "global", "rib", "-j"]).stdout
});

rl.on("line", line => {
  const results = JSON.parse(line);

  results.forEach(r => {
    counter++;
    //console.log()
    //console.log(r.nlri.prefix);
    //console.log(r.attrs);
    //console.log(r.withdrawal);


    ws.write(packEvent(r));
  });

  process.stdout.write(`\r${counter}`);

});

rl.on("close", () => {
  ws.end();
});