brew/Library/Homebrew/cask/lib/hbc/audit.rb

require "hbc/checkable"
require "hbc/download"
require "digest"

class Hbc::Audit
  include Hbc::Checkable

  attr_reader :cask, :download

  def initialize(cask, download: false, check_token_conflicts: false, command: Hbc::SystemCommand)
    @cask = cask
    @download = download
    @check_token_conflicts = check_token_conflicts
    @command = command
  end

  def check_token_conflicts?
    @check_token_conflicts
  end

  def run!
    check_required_stanzas
    check_version
    check_sha256
    check_appcast
    check_url
    check_generic_artifacts
    check_token_conflicts
    check_download
    self
  rescue StandardError => e
    odebug "#{e.message}\n#{e.backtrace.join("\n")}"
    add_error "exception while auditing #{cask}: #{e.message}"
    self
  end

  def success?
    !(errors? || warnings?)
  end

  def summary_header
    "audit for #{cask}"
  end

  private

  def check_required_stanzas
    odebug "Auditing required stanzas"
    %i{version sha256 url homepage}.each do |sym|
      add_error "a #{sym} stanza is required" unless cask.send(sym)
    end
    add_error "a license stanza is required (:unknown is OK)" unless cask.license
    add_error "at least one name stanza is required" if cask.name.empty?
    # TODO: specific DSL knowledge should not be spread around in various files like this
    # TODO: nested_container should not still be a pseudo-artifact at this point
    installable_artifacts = cask.artifacts.reject { |k| [:uninstall, :zap, :nested_container].include?(k) }
    add_error "at least one activatable artifact stanza is required" if installable_artifacts.empty?
  end

  def check_version
    return unless cask.version
    check_no_string_version_latest
  end

  def check_no_string_version_latest
    odebug "Verifying version :latest does not appear as a string ('latest')"
    return unless cask.version.raw_version == "latest"
    add_error "you should use version :latest instead of version 'latest'"
  end

  def check_sha256
    return unless cask.sha256
    check_sha256_no_check_if_latest
    check_sha256_actually_256
    check_sha256_invalid
  end

  def check_sha256_no_check_if_latest
    odebug "Verifying sha256 :no_check with version :latest"
    return unless cask.version.latest? && cask.sha256 != :no_check
    add_error "you should use sha256 :no_check when version is :latest"
  end

  def check_sha256_actually_256(sha256: cask.sha256, stanza: "sha256")
    odebug "Verifying #{stanza} string is a legal SHA-256 digest"
    return unless sha256.is_a?(String)
    return if sha256.length == 64 && sha256[%r{^[0-9a-f]+$}i]
    add_error "#{stanza} string must be of 64 hexadecimal characters"
  end

  def check_sha256_invalid(sha256: cask.sha256, stanza: "sha256")
    odebug "Verifying #{stanza} is not a known invalid value"
    empty_sha256 = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
    return unless sha256 == empty_sha256
    add_error "cannot use the sha256 for an empty string in #{stanza}: #{empty_sha256}"
  end

  def check_appcast
    return unless cask.appcast
    odebug "Auditing appcast"
    check_appcast_has_checkpoint
    return unless cask.appcast.checkpoint
    check_sha256_actually_256(sha256: cask.appcast.checkpoint, stanza: "appcast :checkpoint")
    check_sha256_invalid(sha256: cask.appcast.checkpoint, stanza: "appcast :checkpoint")
    return unless download
    check_appcast_http_code
    check_appcast_checkpoint_accuracy
  end

  def check_appcast_has_checkpoint
    odebug "Verifying appcast has :checkpoint key"
    add_error "a checkpoint sha256 is required for appcast" unless cask.appcast.checkpoint
  end

  def check_appcast_http_code
    odebug "Verifying appcast returns 200 HTTP response code"
    result = @command.run("/usr/bin/curl", args: ["--compressed", "--location", "--user-agent", Hbc::URL::FAKE_USER_AGENT, "--output", "/dev/null", "--write-out", "%{http_code}", cask.appcast], print_stderr: false)
    if result.success?
      http_code = result.stdout.chomp
      add_warning "unexpected HTTP response code retrieving appcast: #{http_code}" unless http_code == "200"
    else
      add_warning "error retrieving appcast: #{result.stderr}"
    end
  end

  def check_appcast_checkpoint_accuracy
    odebug "Verifying appcast checkpoint is accurate"
    result = @command.run("/usr/bin/curl", args: ["--compressed", "--location", "--user-agent", Hbc::URL::FAKE_USER_AGENT, cask.appcast], print_stderr: false)
    if result.success?
      processed_appcast_text = result.stdout.gsub(%r{<pubDate>[^<]*</pubDate>}, "")
      # This step is necessary to replicate running `sed` from the command line
      processed_appcast_text << "\n" unless processed_appcast_text.end_with?("\n")
      expected = cask.appcast.checkpoint
      actual = Digest::SHA2.hexdigest(processed_appcast_text)
      add_warning <<-EOS.undent unless expected == actual
        appcast checkpoint mismatch
        Expected: #{expected}
        Actual: #{actual}
      EOS
    else
      add_warning "error retrieving appcast: #{result.stderr}"
    end
  end

  def check_url
    return unless cask.url
    check_download_url_format
  end

  def check_download_url_format
    odebug "Auditing URL format"
    if bad_sourceforge_url?
      add_warning "SourceForge URL format incorrect. See https://github.com/caskroom/homebrew-cask/blob/master/doc/cask_language_reference/stanzas/url.md#sourceforgeosdn-urls"
    elsif bad_osdn_url?
      add_warning "OSDN URL format incorrect. See https://github.com/caskroom/homebrew-cask/blob/master/doc/cask_language_reference/stanzas/url.md#sourceforgeosdn-urls"
    end
  end

  def bad_url_format?(regex, valid_formats_array)
    return false unless cask.url.to_s =~ regex
    valid_formats_array.none? { |format| cask.url.to_s =~ format }
  end

  def bad_sourceforge_url?
    bad_url_format?(%r{sourceforge},
                    [
                      %r{\Ahttps://sourceforge\.net/projects/[^/]+/files/latest/download\Z},
                      %r{\Ahttps://downloads\.sourceforge\.net/(?!(project|sourceforge)\/)},
                      # special cases: cannot find canonical format URL
                      %r{\Ahttps?://brushviewer\.sourceforge\.net/brushviewql\.zip\Z},
                      %r{\Ahttps?://doublecommand\.sourceforge\.net/files/},
                      %r{\Ahttps?://excalibur\.sourceforge\.net/get\.php\?id=},
                    ])
  end

  def bad_osdn_url?
    bad_url_format?(%r{osd}, [%r{\Ahttps?://([^/]+.)?dl\.osdn\.jp/}])
  end

  def check_generic_artifacts
    cask.artifacts[:artifact].each do |source, target_hash|
      unless target_hash.is_a?(Hash) && target_hash[:target]
        add_error "target required for generic artifact #{source}"
        next
      end
      add_error "target must be absolute path for generic artifact #{source}" unless Pathname.new(target_hash[:target]).absolute?
    end
  end

  def check_token_conflicts
    return unless check_token_conflicts?
    return unless core_formula_names.include?(cask.token)
    add_warning "possible duplicate, cask token conflicts with Homebrew core formula: #{core_formula_url}"
  end

  def core_tap
    @core_tap ||= CoreTap.instance
  end

  def core_formula_names
    core_tap.formula_names
  end

  def core_formula_url
    "#{core_tap.default_remote}/blob/master/Formula/#{cask.token}.rb"
  end

  def check_download
    return unless download && cask.url
    odebug "Auditing download"
    downloaded_path = download.perform
    Hbc::Verify.all(cask, downloaded_path)
  rescue => e
    add_error "download not possible: #{e.message}"
  end
end