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HLS Proxy : HTTP Live Streaming Proxy

Basic Functionality:

  • proxy .m3u8 files, and the video segments (.ts files) they internally reference
  • to all proxied files:
    • add permissive CORS response headers
  • to .m3u8:
    • modify contents such that URLs in the playlist will also pass through the proxy

Advanced Features:

  • inject custom HTTP headers in all outbound proxied requests
  • prefetch video segments (.ts files)
  • use a hook function to conditionally decide which video segments to prefetch
  • use a hook function to conditionally redirect URLs in the playlist (before and/or after they're modified to pass through the proxy)
  • use a hook function to conditionally rewrite URLs after they're received by the proxy

Benefits:

  • any video player (on the LAN) can access the proxied video stream
    • including Chromecast
  • prefetch and caching of video segments ahead-of-time makes playback of the video stream very stable
    • solves buffering problems
  • the proxy can easily be configured to bypass many of the security measures used by video servers to restrict access:
    • CORS response headers (to XHR requests)
      • used by web browsers to enforce a security policy that limits which website(s) may access the content
    • HTTP request headers
      • Origin and Referer are often inspected by the server
        • when these headers don't match the site hosting the content, a 403 Forbidden response is returned (in lieu of the requested data)
    • restricted access to encryption keys
      • often times the encrypted video segments (.ts files) are readily available, but the encryption keys are well protected
        • if the keys can be obtained from another source, then a hook function can be used to redirect only those URL requests

URL Format:

  • [example Javascript]: construction of URL to HLS Proxy for video stream 
      {
    const proxy_url      = 'http://127.0.0.1:8080'
    const video_url      = 'https://example.com/video/master.m3u8'
    const file_extension = '.m3u8'

    const hls_proxy_url  = `${proxy_url}/${ btoa(video_url) }${file_extension}`
  }
  • [example Javascript]: construction of URL to HLS Proxy for video stream w/ "Referer" request header 
      {
    const proxy_url      = 'http://127.0.0.1:8080'
    const video_url      = 'https://example.com/video/master.m3u8'
    const referer_url    = 'https://example.com/videos.html'
    const file_extension = '.m3u8'

    const hls_proxy_url  = `${proxy_url}/${ btoa(`${video_url}|${referer_url}`) }${file_extension}`
  }
  • [example Bash]: construction of URL to HLS Proxy for video stream 
      proxy_url='http://127.0.0.1:8080'
  video_url='https://example.com/video/master.m3u8'
  file_extension='.m3u8'

  hls_proxy_url="${proxy_url}/"$(echo -n "$video_url" | base64 --wrap=0)"$file_extension"
  • [example Bash]: construction of URL to HLS Proxy for video stream w/ "Referer" request header 
      proxy_url='http://127.0.0.1:8080'
  video_url='https://example.com/video/master.m3u8'
  referer_url='https://example.com/videos.html'
  file_extension='.m3u8'

  hls_proxy_url="${proxy_url}/"$(echo -n "${video_url}|${referer_url}" | base64 --wrap=0)"$file_extension"
notes:
  • adding a file extension to the base64 encoded video URL is highly recommended
    • the following file extension values have important significance to indicate the type of file being requested:
      • .m3u8
        HLS manifest
      • .ts
        media segment
      • .key
        encryption key
      • .json
        JSON data
    • though currently,
      • .m3u8
        is the only file extension that receives special treatment
      • all other file types (including those without any file extension) are piped directly to the HTTP response
high-level tools that automate this task:

Installation and Usage: Globally

How to: Install:

npm install --global "@warren-bank/hls-proxy"

How to: Run the server(s):

hlsd <options>

options:
========
--help
--version
--tls
--host <host>
--port <number>
--copy-req-headers
--req-headers <filepath>
--origin <header>
--referer <header>
--useragent <header>
--header <name=value>
--req-options <filepath>
--req-insecure
--req-secure-honor-server-cipher-order
--req-secure-ciphers <string>
--req-secure-protocol <string>
--req-secure-curve <string>
--hooks <filepath>
--prefetch
--max-segments <number>
--cache-timeout <number>
--cache-key <number>
--cache-storage <adapter>
--cache-storage-fs-dirpath <dirpath>
-v <number>
--acl-ip <ip_address_list>
--acl-pass <password_list>
--http-proxy <http[s]://[user:pass@]hostname:port>
--tls-cert <filepath>
--tls-key <filepath>
--tls-pass <filepath>
--manifest-extension <ext>
--segment-extension <ext>

Options:

  • --tls is a flag to start HTTPS proxy, rather than HTTP
    • used as shorthand to automatically configure the following options:
      • --tls-cert
      • --tls-key
      • --tls-pass
    • the values assigned to these options enable the use of a self-signed security certificate that is included in both the git repo and npm package, within the directory:
    • when all of these option are properly specified:
      • the https: protocol is used by all URLs in modified HLS manifests
  • --host is an IP or hostname with an optional port number that can be resolved and is reachable by clients
    • ex: 192.168.0.100:8080
    • used to modify URLs in .m3u8 files
    • when this option is specified without a port number:
      • the value of the --port option is appended
    • when this option is specified and the port number is 443:
      • the https: protocol is used by all URLs in modified HLS manifests
    • when this option is not specified:
      • the value of the "Host" HTTP request header is used
  • --port is the port number that the server listens on
    • ex: 8080
    • when this option is not specified:
      • HTTP proxy binds to: 80
      • HTTPS proxy binds to: 443
  • --copy-req-headers is a flag to enable the duplication of all HTTP request headers sent to the proxy → to the request made by the proxy to the video server
  • --req-headers is the filepath to a JSON data Object containing key:value pairs
    • each key is the name of an HTTP header to send in every outbound request
  • --origin is the value of the corresponding HTTP request header
  • --referer is the value of the corresponding HTTP request header
  • --useragent is the value of the corresponding HTTP request header
  • --header is a single name:value pair
    • this option can be used multiple times to include several HTTP request headers
    • the pair can be written:
      • "name: value"
      • "name=value"
      • "name = value"
  • --req-options is the filepath to a JSON data Object
  • --req-insecure is a flag to override the following environment variable to disable certificate validation for secure https requests:
  • --req-secure-honor-server-cipher-order is a flag to set the following key in the request options Object to configure the context for secure https requests:
    • {honorCipherOrder: true}
  • --req-secure-ciphers is the value to assign to the following key in the request options Object to configure the context for secure https requests:
    • {ciphers: value}
  • --req-secure-protocol is the value to assign to the following key in the request options Object to configure the context for secure https requests:
    • {secureProtocol: value}
  • --req-secure-curve is the value to assign to the following key in the request options Object to configure the context for secure https requests:
    • {ecdhCurve: value}
  • --hooks is the filepath to a CommonJS module that exports a single JSON Object
    • each key is the name of a hook function
    • each value is the implementation of the corresponding Function
    • hook function signatures:
      • "add_request_options": (url, is_m3u8) => request_options
        • conditionally add HTTP request options
        • inputs:
          • url
            • string URL
          • is_m3u8
            • boolean that indicates whether url will request an HLS manifest
        • return value:
          • Object having attributes that are combined with --req-options and used to send the outbound request to url
      • "add_request_headers": (url, is_m3u8) => request_headers
        • conditionally add HTTP request headers
        • return value:
          • Object containing key:value pairs that are combined with --req-headers
            • each key is the name of an HTTP header to send in the outbound request to url
      • "modify_m3u8_content": (m3u8_content, m3u8_url) => new_m3u8_content
        • conditionally modify the content of .m3u8 files before they are parsed to extract URLs
      • "redirect": (url) => new_url
        • conditionally redirect the URLs encountered in .m3u8 files before they are modified to pass through the proxy
      • "redirect_final": (url) => new_url
        • conditionally redirect the URLs encountered in .m3u8 files after they are modified to pass through the proxy
      • "rewrite": (url) => new_url
        • conditionally rewrite the URLs requested by clients before they are proxied
      • "prefetch": (url) => boolean
        • conditionally decide whether to prefetch video segments on a per-URL basis
        • return value must be a strict boolean type (ie: true or false)
        • otherwise, the default behavior supersedes
          • to only prefetch .ts files
      • "prefetch_segments": (prefetch_urls, max_segments, is_vod, seg_duration_ms, perform_prefetch) => new_prefetch_urls
        • conditionally filter the list of video segment URLs that are pending prefetch, when more than --max-segments are contained in an HLS manifest
        • inputs:
          • prefetch_urls
            • array of string video segment URLs
          • max_segments
            • integer that denotes the max length of the return value
          • is_vod
            • boolean that indicates whether the HLS manifest is for video-on-demand
              • if true:
                • the video is not a live stream
                • the HLS manifest is complete and contains URLs for every video segment that would be needed to play the entire stream from start to finish
          • seg_duration_ms
            • integer that represents the duration (ms) of each video segment in the HLS manifest
          • perform_prefetch
            • function that accepts an array of string video segment URLs, and immediately begins to prefetch all corresponding segments
        • return value:
          • array of string video segment URLs that is a subset of prefetch_urls
            • can be emtpy (ex: when using perform_prefetch)
        • pre-conditions:
          • the length of prefetch_urls is > max_segments
        • post-conditions:
          • the length of the return value array is <= max_segments
      • "request_intervals": (add_request_interval) => {}
        • enables the use of a cookie jar for all outbound HTTP requests
        • adds any number of timers that each execute at individually specified intervals
        • when each timer executes, it is passed an HTTP request client that is preconfigured to:
          • include the request headers that are specified by other relevant options
          • utilize the same cookie jar as all other outbound HTTP requests
            • this allows the implementation of custom logic that may be required by one or more video hosts to periodically refresh or update session cookies
        • an example would better illustrate usage: 
            module.exports = {
    request_intervals: (add_request_interval) => {

      add_request_interval(
        0, // run timer once at startup to initialize cookies
        (request) => {
          request('https://example.com/login', {username: 'me', password: '12345'})
        }
      )

      add_request_interval(
        (1000 * 60 * 5), // run timer at 5 minute interval to refresh cookies
        (request) => {
          request('https://example.com/heart-beat')
        }
      )

    }
  }
        • more advanced configuration of the call to the HTTP request client is possible
          • the 1st parameter is required, and must be a URL string
          • the 2nd parameter is optional, and can contain POST data
          • the 3rd parameter is optional, and can be used for more advanced configuration options
        • usage of this HTTP request client is documented here
          • specifically, pay careful attention to the signatures for:
            • the latter two input parameters
            • the attributes of the Object that is resolved by the Promise in the return value (if the content of the response is needed)
  • --prefetch is a flag to enable the prefetch and caching of video segments
    • when .m3u8 files are downloaded and modified inflight, all of the URLs in the playlist are known
    • at this time, it is possible to prefetch the video segments (.ts files)
    • when the video segments (.ts files) are requested at a later time, the data is already cached (in memory) and can be returned immediately
  • --max-segments is the maximum number of video segments (.ts files) to hold in each cache
    • this option is only meaningful when --prefetch is enabled
    • a cache is created for each unique HLS manifest URL
      • all of the video segments (.ts files) associated with each distinct video stream are stored in isolation
    • when any cache grows larger than this size, the oldest data is removed to make room to store new data
    • when this option is not specified:
      • default value: 20
  • --cache-timeout is the maximum number of seconds that any segment cache can remain unused before its contents are cleared (to reduce wasted space in memory)
    • this option is only meaningful when --prefetch is enabled
    • when this option is not specified:
      • default value: 60
  • --cache-key sets the type of string used to represent keys in the cache hashtable when logged
    • this option is only meaningful when --prefetch is enabled
    • scope:
      • v0.16.0 and earlier
        • keys in the cache hashtable used this string representation
      • v0.16.1 and later
        • keys in the cache hashtable are full URLs
          • the data structure to cache video segments (.ts files) was updated
          • each unique HLS manifest is associated with a distinct FIFO list that holds --max-segments
          • when a video segment is requested
            • the proxy needs to search every FIFO list for a match
            • when keys in the cache hashtable lose fidelity, collisions can occur and the wrong video segment can be returned
            • full URLs are unique and guarantee correct behavior
    • 0 (default):
      • sequence number of .ts file w/ .ts file extension (ex: "123.ts")
        • pros:
          • shortest type of string
          • makes the log output easiest to read
        • cons:
          • in the wild, I've encountered video servers that assign each .ts file a unique filename that always terminate with the same static sequence number
            • this is a strange edge case, but this option provides an easy workaround
    • 1:
      • full filename of .ts file
    • 2:
      • full URL of .ts file
  • --cache-storage selects a storage adapter that is used to hold the cache of prefetched video segments
    • this option is only meaningful when --prefetch is enabled
    • memory (default):
      • uses RAM
    • filesystem:
      • each video segment is written to a new file within a specified directory
      • filenames are random and unique
  • --cache-storage-fs-dirpath specifies the directory in which to save video segments when using a filesystem-based cache storage adapter
    • this option is only meaningful when --prefetch is enabled and --cache-storage is filesystem
  • -v sets logging verbosity level:
    • -1:
      • silent
    • 0 (default):
      • show errors only
    • 1:
      • show an informative amount of information
    • 2:
      • show technical details
    • 3:
      • show an enhanced technical trace (useful while debugging unexpected behavior)
    • 4:
      • show the content of .m3u8 files (both before and after URLs are modified)
  • --acl-ip restricts proxy server access to clients at IP addresses in whitelist
    • ex: "192.168.1.100,192.168.1.101,192.168.1.102"
  • --acl-pass restricts proxy server access to requests that include a password querystring parameter having a value in whitelist
    • ex: "1111,2222,3333,4444,5555"
  • --http-proxy enables all outbound HTTP and HTTPS requests from HLS-Proxy to be tunnelled through an additional external web proxy server
  • --tls-cert is the filepath to a security certificate to use for HTTPS
  • --tls-key is the filepath to the private key for the --tls-cert security certificate
  • --tls-pass is the filepath to a text file containing the security passphrase for the --tls-key private key
    • optional, not required when the --tls-key private key was created without a security passphrase
  • --manifest-extension is the file extension associated with HLS manifests
    • default value: m3u8
  • --segment-extension is the file extension associated with media segments
    • default value: ts

Examples:

  1. print help
    hlsd --help

  2. print version
    hlsd --version

  3. start HTTP proxy at default host:port
    hlsd

  4. start HTTP proxy at default host and specific port
    hlsd --port "8080"

  5. start HTTP proxy at specific host:port
    hlsd --host "192.168.0.100" --port "8080"

  6. start HTTPS proxy at default host:port
    hlsd --tls

  7. start HTTPS proxy at specific host:port
    hlsd --tls --host "192.168.0.100" --port "8081"

  8. start HTTPS proxy at default host:port and send specific HTTP headers
    hlsd --tls --req-headers "/path/to/request/headers.json"

  9. start HTTPS proxy at default host:port and enable prefetch of 10 video segments
    hlsd --tls --prefetch --max-segments 10

  10. start HTTPS proxy using a non-generic security certificate
    hlsd --tls-cert "/path/to/cert.pem" --tls-key "/path/to/key.pem" --tls-pass "/path/to/pass.phrase"

Installation and Usage: Working with a Local git Repo

How to: Install:

git clone "https://github.com/warren-bank/HLS-Proxy.git"
cd "HLS-Proxy"
npm install

How to: Run the server(s):

# ----------------------------------------------------------------------
# If using a port number >= 1024 on Linux, or
# If using Windows:
# ----------------------------------------------------------------------
npm start [-- <options>]

# ----------------------------------------------------------------------
# https://www.w3.org/Daemon/User/Installation/PrivilegedPorts.html
#
# Linux considers port numbers < 1024 to be privileged.
# Use "sudo":
# ----------------------------------------------------------------------
npm run sudo [-- <options>]

Options:

Examples:

  1. print help
    npm start -- --help

  2. start HTTP proxy at specific host:port
    npm start -- --host "192.168.0.100" --port "8080"

  3. start HTTPS proxy at specific host:port
    npm start -- --host "192.168.0.100" --port "8081" --tls

  4. start HTTP proxy at default host:port with escalated privilege
    npm run sudo -- --port "80"

  5. start HTTPS proxy at default host:port with escalated privilege
    npm run sudo -- --port "443" --tls

  6. start HTTP proxy at specific port and send custom "Referer" request header for specific video stream

npm start -- --port "8080"

h_referer='http://XXX:80/page.html'

URL='https://httpbin.org/headers'
URL="${URL}|${h_referer}"
URL=$(echo -n "$URL" | base64 --wrap=0)
URL="http://127.0.0.1:8080/${URL}.json"
# URL='http://127.0.0.1:8080/aHR0cHM6Ly9odHRwYmluLm9yZy9oZWFkZXJzfGh0dHA6Ly9YWFg6ODAvcGFnZS5odG1s.json'
curl --silent "$URL"
  1. start HTTP proxy at specific port and send custom request headers
headers_file="${TMPDIR}/headers.json"
echo '{"Origin" : "http://XXX:80", "Referer": "http://XXX:80/page.html"}' > "$headers_file"
npm start -- --port "8080" --req-headers "$headers_file"

URL='https://httpbin.org/headers'
URL=$(echo -n "$URL" | base64 --wrap=0)
URL="http://127.0.0.1:8080/${URL}.json"
# URL='http://127.0.0.1:8080/aHR0cHM6Ly9odHRwYmluLm9yZy9oZWFkZXJz.json'
curl --silent "$URL"
  1. start HTTPS proxy at specific port and send custom request headers
headers_file="${TMPDIR}/headers.json"
echo '{"Origin" : "http://XXX:80", "Referer": "http://XXX:80/page.html"}' > "$headers_file"
npm start -- --port "8081" --req-headers "$headers_file" --tls -v 1

URL='https://127.0.0.1:8081/aHR0cHM6Ly9odHRwYmluLm9yZy9oZWFkZXJz.json'
curl --silent --insecure "$URL"
  1. start HTTPS proxy at specific port and send custom request headers
h_origin='http://XXX:80'
h_referer='http://XXX:80/page.html'
h_useragent='Chromium'
h_custom_1='X-Foo: 123'
h_custom_2='X-Bar: baz'
npm start -- --port "8081" --origin "$h_origin" --referer "$h_referer" --useragent "$h_useragent" --header "$h_custom_1" --header "$h_custom_2" --tls -v 1

URL='https://127.0.0.1:8081/aHR0cHM6Ly9odHRwYmluLm9yZy9oZWFkZXJz.json'
curl --silent --insecure "$URL"

Observations:

  • when playing the proxied HLS video stream in an HTML5 player in a Chromium web browser (ex: THEOplayer)
    • if the page hosting the HTML5 video player is served from HTTPS:
      • when running only the HTTP proxy server:
        • the XHR requests from the player to the HTTP proxy server raise a security warning (insecure content)
        • the XHR requests get elevated to HTTPS, which are unanswered (since the HTTPS proxy server isn't running)
      • when running only the HTTPS proxy server:
        • the XHR requests from the player to the HTTPS proxy server will silently fail
        • this is because the HTTPS proxy server is using a self-signed security certificate
        • this certificate needs to be (temporarily) allowed
        • once it is, the video stream works perfectly
          • to allow the certificate:
            • browse to a URL hosted by the proxy server ( example )
            • you should see the warning: NET::ERR_CERT_AUTHORITY_INVALID Your connection is not private
            • click: Advanced
            • click: Proceed to 127.0.0.1 (unsafe)
            • done
  • when playing the proxied HLS video stream on a Chromecast
    • the HTTP proxy server works perfectly
    • the HTTPS proxy server doesn't begin playback
      • not sure why..
      • probably has something to do with the Chromecast's browser security policies
      • a more respectable security certificate (ie: more expensive) would probably fix it

Summary of (Rarely) Observed OpenSSL Connection Errors:

  • error:
    ssl3_check_cert_and_algorithm:dh key too small

    1. attempted fix:
      --req-secure-ciphers "AES128-SHA"

  • error:
    SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure

    1. attempted fix:
      --req-secure-protocol "SSLv3_method"
      • result:
        Error: SSLv3 methods disabled
      • issue:
    2. attempted fix:
      --req-secure-curve "auto"

Other Projects:

(directly related, but very loosely coupled)
  • Webcast-Reloaded
    • consists of 2 parts:
      1. a Chromium web browser extension (.crx)
        • on each browser tab, it's silently watching the URL of all outbound requests
        • every requested URL matching a regex pattern that identifies it to be a video file is displayed in the modal window that toggles open when the extension's icon is clicked
        • links in this modal window open to URLs of component #2
      2. a static website
        • there is a selection of several HTML5 videos players
          • each is better at some things and worse at others
          • each integrates with a different Chromecast receiver app
        • there is a page to help redirect the intercepted video URL through a local instance of HLS Proxy

Other Projects:

(unrelated, but somewhat similar in scope and purpose)
  • Streamlink
    • notes:
      • this project has way more features, and is way more polished
      • though its main purpose is to transcode online video with ffmpeg and pipe the output into another program, it can be configured to not load a video player and instead start a web server
      • it can strongly support individual websites through single-purpose plugins
      • it can also support streams via direct URLs
        • using URLs from the wild will have mixed results, since cookies and headers and authentication aren't being managed by any plugin
    • docs:
    • binaries:
      • Windows portable
        • minimum system requirements:
          • Windows 7 SP1
          • .NET Framework 4.5
    • usage test:
      • streamlink --player-external-http --player-external-http-port 8080 --default-stream best --http-ignore-env --http-no-ssl-verify --url "https://XXX/video.m3u8"
    • usage test result:

Major Versions:

  • v1.x
    • commit history is in branch: v01
    • summary:
      • m3u8 manifest parser uses regex patterns to identify all URL patterns without any special knowledge of the m3u8 manifest specification
      • internal proxy module exports a function that accepts an instance of http.Server and adds event listeners to process requests
    • system requirements:
  • v2.x
    • commit history is in branch: v02
    • summary:
      • m3u8 manifest parser uses regex patterns to identify all URL patterns without any special knowledge of the m3u8 manifest specification
      • internal proxy module exports an Object containing event listeners to process requests that can be either:
        • added to an instance of http.Server
        • added to an Express.js application as middleware to handle a custom route
          • important limitation: since / is a valid character in a base64 encoded URL, the path for a custom route needs to end with a character that is not allowed in base64 encoding (ex: '/proxy_/*')
    • system requirements:
  • v3.x
    • commit history is in branch: v03
    • summary:
      • m3u8 manifest parser uses special knowledge of the m3u8 manifest specification to contextually identify URLs
      • internal proxy module exports an Object containing event listeners to process requests that can be either:
        • added to an instance of http.Server
        • added to an Express.js application as middleware to handle a custom route
          • important requirement: the path for a custom route needs to include exactly one unnamed parameter that matches the base64 encoded URL and (optionally) a file extension (ex: '/proxy/*')
          • the use of nested routers is supported
    • system requirements:

Legal:

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Node.js server to proxy HLS video streams

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