express-range-tracker

express-range-tracker

Detects semantically correct usage of the range header by firing the onDownloaded event when all chunks related to the current ip are downloaded

Usage

const express = require("express");
const rangeTracker = require("express-range-tracker");

express()
  .use(
    rangeTracker({
      timestampFunction: Date.now,
      onDownloaded: (req, res, next) => {
        /* ... */
      },
    })
  )
  .listen(3000);

timestampFunction - Calculates datetime of range chunk request

storage - an Object that supports indexing, associative array. {} by default

onDownloaded - event that behaves as middleware

onDeadlineReached - event that fires when maxDelay exceeds timestamp window between the last and the new timestamps

allowedTraits - array of functions that determine whitelist of range header behavior. true if match, false otherwise

interface Trait {
  from: number;
  to: number;
  timestamp: number;
}

(previous: Trait, current: Trait) => boolean;

bannedTraits - array of functions that determine blacklist of range header behavior. true if match, false otherwise

(previous: Trait, current: Trait) => boolean;

onSimilarTrait - fires when another ips had the same range behavior as the current ip. The current ip will not be in the list

const track = rangeTracker({
  storage,
  onSimilarTrait: (ips) => {
    console.log(ips.length);
  },
});

onRobotic - fires when range is malformed in some way:

• malformed - does not conform to range spec
• digits - from is bigger than to in range segment
• empty - range header is present but length of string is 0
• absent - request of content that should have range header but does not exist
• negative - negative from or to range detected

onRobotic(req, reason);

onSimilarTimestamp - function that fires on clients with same range request timestamp windows

onSimilarTimestamp(req, ips);

onRangeOverflow - fires with either parts or overflow reason when segment count is larger than maxParts or max value is smaller than the biggest part of any segment, respectively

const track = rangeTracker({
  storage,
  maxParts: 3,
  max: 50
  onRangeOverflow: (req, reason) => {
    console.log(reason);
  },
});

Test

npm test