Skip to content

Steam CDN Client

Jump to bottom
Alex Corn edited this page Jul 9, 2022 · 6 revisions

As of v3.16.0, a SteamUser can interact with Steam's CDN and download content. This is currently experimental.

Code examples:

Properties

contentServersReady

A boolean indicating whether or not the preliminary list of content servers has been received. If this is true, then you can safely use getContentServers.

Methods

getContentServers([appid, ]callback)

  • appid - Optional. If you know the AppID of the app you're trying to download, pass it here as some content servers only provide content for specific games.
  • callback - A function to be called when the requested data is available
    • err - An Error object on failure, or null on success
    • servers - An array of objects, each of which contains info about a content server

Requests a list of 20 content servers from Steam for your current region. The first time this returns success, the list will be cached in memory indefinitely, and subsequent calls will return the cached data immediately in the callback.

getDepotDecryptionKey(appID, depotID, callback)

  • appID - The AppID of the app for which you want a decryption key
  • depotID - The ID of the depot in the app for which you want a key
  • callback - Called when the requested data is available
    • err - An Error object on failure, or null on success
    • key - On success, the requested decryption key as a Buffer

Requests the decryption key for a particular depot. Depot decryption keys are required to decrypt filenames in manifests and content in data chunks.

On success, this will be saved to disk (in the designated dataDirectory) and the local data will be returned to the callback immediately for subsequent requests for this appID/depotID pair.

Locally cached data expires after 14 days, after which time it will be re-requested.

getCDNAuthToken(appID, depotID, hostname, callback)

  • appID - The ID of the app for which you want an auth token
  • depotID - The ID of the depot for which you want an auth token
  • hostname - The hostname of the content server for which you want an auth token
  • callback - Called when the requested data is available
    • err - An Error object on failure, or null on success
    • token - The requested auth token on success, as a string
    • expires - On success, this is the time when this token will expire, as a Date object

Requests an auth token for a particular DepotID to be downloaded from a given content server. One token is required per depot and per content server. On success, the token will be cached in memory until it expires or the SteamUser disconnects.

This token will usually be an empty string, but not always.

getManifestRequestCode(appID, depotID, manifestID, branchName[, branchPassword], callback)

  • appID - The AppID of the app for which you want a manifest request code
  • depotID - The ID of the depot for which you want a manifest request code
  • manifestID - The ID of the manifest for which you want a manifest request code
  • branchName - The name of the branch containing the manifest (use public for the default branch)
  • branchPassword - The password for the branch, if it's a private branch
  • callback - Called when the requested data is available
    • err - An Error object on failure, or null on success
    • response - The response object
      • requestCode - The manifest request code, as a string

v4.20.0 or later is required to use this method

Requests a manifest request code, to be used when downloading a manifest.

More info here

getManifest(appID, depotID, manifestID[, branchName][, branchPassword], callback)

  • appID - The AppID of the app for which you want a manifest
  • depotID - The ID of the depot for which you want a manifest
  • manifestID - The ID of the manifest you want, as a string
  • branchName - The name of the branch containing the manifest (use public for the default branch)
  • branchPassword - Optional. The password for the branch, if it's a private branch
  • callback - Called when the requested data is available
    • err - An Error object on failure, or null on success
    • manifest - The manifest, as an object

Performs the following:

  1. Retrieves a list of content servers (via getContentServers)
  2. Chooses a random content server from the list
  3. Retrieves a CDN auth token for the chosen content server, if the content server needs one
  4. Retrieves a manifest request code
  5. Downloads the specified manifest from the chosen content server
  6. Decompresses the manifest
  7. Parses the manifest into an object
  8. If the filenames in the manifest are encrypted, retrieves the depot's decryption key (via getDepotDecryptionKey) and decrypts the filenames

A manifest ID is essentially a revision number. Every time a depot is updated, a new manifest ID is issued. You can download any manifest if you have its ID (and you own the app). A manifest contains a listing of all files in the depot, their sizes, and metadata about the chunks which make them up.

getRawManifest(appID, depotID, manifestID, callback)

  • appID - The AppID of the app for which you want a manifest
  • depotID - The ID of the depot for which you want a manifest
  • manifestID - The ID of the manifest you want, as a string
  • branchName - The name of the branch containing the manifest (use public for the default branch)
  • branchPassword - Optional. The password for the branch, if it's a private branch
  • callback - Called when the requested data is available
    • err - An Error object on failure, or null on success
    • manifest - The manifest, as a Buffer

Same as getManifest, but stops after step 5 (e.g. decompresses the manifest but doesn't parse it).

downloadChunk(appID, depotID, chunkSha1[, contentServer], callback)

  • appID - The AppID of the app from which you want a chunk
  • depotID - The ID of the depot from which you want a chunk
  • chunkSha1 - The SHA1 hash of the chunk you want to download, as a string. You can get this from a manifest.
  • contentServer - Optional. Should be an object returned by getContentServers. Omit to choose a random one.
  • callback - Called when the requested data is available
    • err - An Error object on failure, or null on success
    • data - The chunk's data, as a Buffer

Performs the following:

  1. If contentServer was not provided, retrieves the content server list (via getContentServers) and chooses a random one
  2. Retrieves a CDN auth token for the specified appID and content server, if the content server needs one
  3. Retrieves the depot's decryption key
  4. Downloads the chunk data from the chosen content server
  5. Decrypts the downloaded data
  6. Decompresses the decrypted data
  7. Verifies the decompressed data with the provided SHA1 hash

downloadFile(appID, depotID, fileManifest[, outputFilePath], callback)

  • appID - The AppID of the app from which you want a file
  • depotID - The ID of the depot from which you want a file
  • fileManifest - Should be an object from the files array of a manifest, as-is
  • outputFilePath - Optional. If you want to write this file to disk, this should be a string containing the desired destination path (all parent directories must exist). If the file already exists, it will be overwritten. If omitted, then the downloaded file will be stored in memory.
  • callback - See below
    • err - An Error object on failure, or null on success
    • response - The response object

Downloads a particular file from the CDN. Retrieves the content server list (via getContentServers) and chooses 4 servers at random. Then, downloads up to 4 chunks concurrently from the chosen servers (one chunk per server) via downloadChunk until the entire file is downloaded. If a chunk fails, its content server is discarded and a new one is chosen. If it continues to fail, the entire download is aborted.

If you opt to write the download to disk (by providing outputFilePath), then the space is pre-allocated before any chunks are downloaded. As chunks finish downloading, they are patched into the pre-allocated space. The maximum amount of memory that should be in use at a time due to downloads which are being written to disk is ~4-5 MB.

If you do not provide an outputFilePath, then the entire file will be stored in memory. The memory will be pre-allocated before any chunks are downloaded. If you opt to download a very large file this way, be sure that you have enough memory available.

The file's checksum is validated with the one in the fileManifest before success is returned to the callback.

Note that on failure, any allocated disk space will not be automatically cleaned up. The garbage collector will reclaim any memory, however.

This method has a special callback that can be called multiple times. The callback, if provided, will be invoked with an err argument and a response object argument. The callback will be emitted during the download to report progress, and again at the end when the download completes. Check the type property of the response object to know what type of event has occurred. Possible events are:

  • progress - If the callback is invoked with this type of event, the following properties are also defined:
    • bytesDownloaded - How many bytes have been downloaded so far
    • totalSizeBytes - The total size of the file in bytes
  • complete - If the callback is invoked with this type of event, the download is complete. No more progress events will be emitted. These properties are defined:
    • file - If and only if you aren't streaming this download to a file on disk, this is a Buffer containing the downloaded file

The Promise returned by this method will also be fulfilled for a complete event, with the same data as the callback. If an error occurs, the Promise will be rejected and the callback (if provided) will be invoked with an Error event as its first argument.

getAppBetaDecryptionKeys(appID, password, callback)

  • appID - The AppID of the app for which you want beta decryption keys
  • password - The password you want to use to get keys, as a string
  • callback - Called when the requested data is available
    • err - An Error object on failure, or null on success
    • branches - An object whose keys are branch names and values are Buffers containing keys

Given a beta access code (password), requests decryption keys for matching branches. Those keys can be used to decrypt the encrypted_gid_2 value in those branches (in the data retrieved from getProductInfo).

You can use symmetricDecryptECB in @doctormckay/steam-crypto to decrypt those values, which are manifest IDs. Just read the decrypted data as an unsigned little-endian 64-bit integer.

Clone this wiki locally