index.js

const got = require('got')
const express = require('express')

const app = express()

app.disable('etag')

app.get('/', (request, response) => {
  response.status(200).json({
    'message': "Welcome to Twitch API"
  })
})

app.get('/hls', (request, response) => {
  response.status(404).json({
    'message': 'unknown channel name'
  })
})

app.get('/hls/:id', async (request, response) => {
  try {
    let id = request.params.id
    let token = await got(`https://gql.twitch.tv/gql`, {
      method: 'POST',
      responseType: 'json',
      retry: {
        limit: 4
      },
      throwHttpErrors: false,
      headers: {
        'Client-ID': 'kimne78kx3ncx6brgo4mv6wki5h1ko',
        'Content-Type': 'application/json',
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.111 Safari/537.36',
        'X-Device-Id': 'twitch-web-wall-mason',
        'Device-ID': 'twitch-web-wall-mason'
      },
      body: JSON.stringify({
        "operationName": "PlaybackAccessToken",
        "extensions": {
          "persistedQuery": {
            "version": 1,
            "sha256Hash": "0828119ded1c13477966434e15800ff57ddacf13ba1911c129dc2200705b0712"
          }
        },
        "variables": {
          "isLive": true,
          "login": id,
          "isVod": false,
          "vodID": "",
          "playerType": "embed"
        }
      })
    })

    switch (token.statusCode) {
      default: //Error with connect with Twitch API
        response.status(500).json({
          'message': 'Error with Twitch API'
        })
        break
      case 200: //Channel founded
        if (token.body.data.streamPlaybackAccessToken === null) { //Channel not found
          response.status(404).json({
            'message': 'Channel not found'
          })
        } else {
          function base64Encode(data) {
            return Buffer.from(data).toString('base64')
          }

          function cleanupAllAdStuff(data) {
            return data
              .replace(/X-TV-TWITCH-AD-URL="[^"]+"/g, 'X-TV-TWITCH-AD-URL="javascript:alert(\'pogo\')"')
              .replace(
                /X-TV-TWITCH-AD-CLICK-TRACKING-URL="[^"]+"/g,
                'X-TV-TWITCH-AD-CLICK-TRACKING-URL="javascript:alert(\'pogo\')"'
              )
              .replace(/X-TV-TWITCH-AD-ADVERIFICATIONS="[^"]+"/g, `X-TV-TWITCH-AD-ADVERIFICATIONS="${base64Encode('{}')}"`)
              .replace(/#EXT-X-DATERANGE.+CLASS=".*ad.*".+\n/g, '')
              .replace(/\n#EXTINF.+(?<!live)\nhttps:.+/g, '');
          }

          let url = `http://usher.twitch.tv/api/channel/hls/${id}.m3u8?player=twitchweb&&token=${token.body.data.streamPlaybackAccessToken.value}&sig=${token.body.data.streamPlaybackAccessToken.signature}&allow_audio_only=true&allow_source=true&type=any&p=${parseInt(Math.random() * 999999)}`
          let hls = await got(url, {
            method: 'GET',
            responseType: 'text',
            retry: {
              limit: 4
            },
            throwHttpErrors: false,
            headers: {
              'X-Device-Id': 'twitch-web-wall-mason',
              'Device-ID': 'twitch-web-wall-mason'
            }
          })
          switch (hls.statusCode) {
            default: //m3u8 data doesn't exsit
              response.status(404).json({
                'message': 'm3u8 data not found'
              })
              break
            case 200: //m3u8 data exist
              hls = cleanupAllAdStuff(hls.body)
              hls = hls.replace(/.*#.*\n?/gm, '')
              response.status(200).json(hls.split('\n'))
              break
          }
        }
    }
  } catch (error) {
    response.status(500).json({
      message: 'processing error',
      error: error
    })
  }
})

app.get('/proxy/*', async (request, response) => {
  try {
    const url = request.params['0'] + '?' + Object.entries(request.query).map(element => element.join('=')).join('&')
    const domain = (new URL(url)).hostname
    if (domain === 'usher.ttvnw.net') {
      const headers = {
        'host': domain,
        'user-agent': request.headers['user-agent']
      }
      let hls = await got(url, {
        method: 'GET',
        responseType: 'text',
        retry: {
          limit: 4
        },
        throwHttpErrors: false,
        headers: headers
      })
      response.status(hls.statusCode).send(hls.body)
    } else {
      response.status(403).json({
        message: 'URL not allowed'
      })
    }
  } catch (error) {
    response.status(500).json({
      message: 'processing error',
      error: error
    })
  }
})

app.listen(8080, () => {
  console.log("API started")
})