client/src/assets/player/p2p-media-loader/segment-validator.ts

   1 import { Segment } from 'p2p-media-loader-core'
   2 import { basename } from 'path'
   3
   4 function segmentValidatorFactory (segmentsSha256Url: string) {
   5   const segmentsJSON = fetchSha256Segments(segmentsSha256Url)
   6
   7   return async function segmentValidator (segment: Segment) {
   8     const segmentName = basename(segment.url)
   9
  10     const hashShouldBe = (await segmentsJSON)[segmentName]
  11     if (hashShouldBe === undefined) {
  12       throw new Error(`Unknown segment name ${segmentName} in segment validator`)
  13     }
  14
  15     const calculatedSha = bufferToEx(await sha256(segment.data))
  16     if (calculatedSha !== hashShouldBe) {
  17       throw new Error(`Hashes does not correspond for segment ${segmentName} (expected: ${hashShouldBe} instead of ${calculatedSha})`)
  18     }
  19   }
  20 }
  21
  22 // ---------------------------------------------------------------------------
  23
  24 export {
  25   segmentValidatorFactory
  26 }
  27
  28 // ---------------------------------------------------------------------------
  29
  30 function fetchSha256Segments (url: string) {
  31   return fetch(url)
  32     .then(res => res.json())
  33     .catch(err => {
  34       console.error('Cannot get sha256 segments', err)
  35       return {}
  36     })
  37 }
  38
  39 function sha256 (data?: ArrayBuffer) {
  40   if (!data) return undefined
  41
  42   return window.crypto.subtle.digest('SHA-256', data)
  43 }
  44
  45 // Thanks: https://stackoverflow.com/a/53307879
  46 function bufferToEx (buffer?: ArrayBuffer) {
  47   if (!buffer) return ''
  48
  49   let s = ''
  50   const h = '0123456789abcdef'
  51   const o = new Uint8Array(buffer)
  52
  53   o.forEach((v: any) => s += h[ v >> 4 ] + h[ v & 15 ])
  54
  55   return s
  56 }