Module: Depot::UpdateDownloader

Defined in:
lib/depot/update_downloader.rb

Constant Summary collapse

MAX_DOWNLOAD_BYTES = 
2 * 1024 * 1024 * 1024
MAX_REDIRECTS = 
5
OPEN_TIMEOUT_SECONDS = 
15
READ_TIMEOUT_SECONDS = 
60
KNOWN_SUFFIXES = 
[
  ".flatpakref",
  ".AppImage",
  ".appimage",
  ".tar.gz",
  ".tgz",
  ".tar.xz",
  ".txz",
  ".tar.zst",
  ".tzst",
  ".deb",
  ".rpm"
].freeze

Class Method Summary collapse

Class Method Details

.download(url, max_bytes: MAX_DOWNLOAD_BYTES, redirects: MAX_REDIRECTS) ⇒ Object 



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# File 'lib/depot/update_downloader.rb', line 33

def download(url, max_bytes: MAX_DOWNLOAD_BYTES, redirects: MAX_REDIRECTS)
  return Result.err("Update downloader requires a block.") unless block_given?

  uri = parse_https_url(url)
  return uri unless uri.ok?

  Dir.mktmpdir("depot-update-") do |dir|
    path = File.join(dir, "package#{suffix_for(uri.value.path)}")
    result = download_to(uri.value, path, max_bytes:, redirects:)
    return result unless result.ok?

    yield path, result.value
  end
rescue SystemCallError => e
  Result.err("Could not download update: #{e.message}")
end

.download_to(uri, path, max_bytes:, redirects:) ⇒ Object 



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# File 'lib/depot/update_downloader.rb', line 64

def download_to(uri, path, max_bytes:, redirects:)
  return Result.err("Update download redirected too many times.") if redirects.negative?

  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true
  http.open_timeout = OPEN_TIMEOUT_SECONDS
  http.read_timeout = READ_TIMEOUT_SECONDS

  request = Net::HTTP::Get.new(uri)
  request["User-Agent"] = "Depot/#{Depot::VERSION}"
  result = nil
  http.request(request) do |response|
    result = case response
             when Net::HTTPSuccess
               stream_response(uri, response, path, max_bytes)
             when Net::HTTPRedirection
               follow_redirect(uri, response, path, max_bytes:, redirects:)
             else
               Result.err("Update download failed: HTTP #{response.code}")
             end
  end
  result || Result.err("Update download failed before Depot received a response.")
rescue Timeout::Error, IOError, SystemCallError => e
  Result.err("Update download failed: #{e.message}")
end

.follow_redirect(uri, response, path, max_bytes:, redirects:) ⇒ Object 



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# File 'lib/depot/update_downloader.rb', line 90

def follow_redirect(uri, response, path, max_bytes:, redirects:)
  location = response["location"].to_s
  return Result.err("Update download redirected without a location.") if location.empty?

  redirected = URI.join(uri, location)
  return Result.err("Update redirects must stay on https://.") unless redirected.is_a?(URI::HTTPS)

  download_to(redirected, path, max_bytes:, redirects: redirects - 1)
rescue URI::InvalidURIError
  Result.err("Update download redirected to an invalid URL.")
end

.https_url?(url) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/depot/update_downloader.rb', line 50

def https_url?(url)
  parse_https_url(url).ok?
end

.parse_https_url(url) ⇒ Object 



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# File 'lib/depot/update_downloader.rb', line 54

def parse_https_url(url)
  uri = URI.parse(url.to_s)
  return Result.err("Update URL must use https://.") unless uri.is_a?(URI::HTTPS)
  return Result.err("Update URL is missing a host.") if uri.host.to_s.empty?

  Result.ok(uri)
rescue URI::InvalidURIError
  Result.err("Update URL must be a valid https:// URL.")
end

.stream_response(uri, response, path, max_bytes) ⇒ Object 



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# File 'lib/depot/update_downloader.rb', line 102

def stream_response(uri, response, path, max_bytes)
  content_length = response["content-length"].to_i
  if content_length.positive? && content_length > max_bytes
    return Result.err("Update is too large to download safely (#{content_length} bytes).")
  end

  digest = Digest::SHA256.new
  bytes = 0
  File.open(path, "wb") do |file|
    response.read_body do |chunk|
      bytes += chunk.bytesize
      return Result.err("Update exceeded Depot's #{max_bytes} byte safety limit.") if bytes > max_bytes

      digest.update(chunk)
      file.write(chunk)
    end
  end

  return Result.err("Update download was empty.") if bytes.zero?

  Result.ok(
    {
      "url" => uri.to_s,
      "size" => bytes,
      "sha256" => digest.hexdigest
    }
  )
end

.suffix_for(path) ⇒ Object 



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# File 'lib/depot/update_downloader.rb', line 131

def suffix_for(path)
  basename = File.basename(path.to_s)
  KNOWN_SUFFIXES.find { |suffix| basename.end_with?(suffix) } || File.extname(basename)
end