# class Gem::RemoteFetcher

`RemoteFetcher` handles the details of fetching gems and gem information from a remote source.

### Attributes

headers [RW]

### Public Class Methods

fetcher ()
Source

    # File lib/rubygems/remote_fetcher.rb, line 55
    def self.fetcher
      @fetcher ||= new Gem.configuration[:http_proxy]
    end

Cached `RemoteFetcher` instance.

new (proxy=nil, dns=nil, headers={})
Source

    # File lib/rubygems/remote_fetcher.rb, line 75
    def initialize(proxy=nil, dns=nil, headers={})
      require_relative "core_ext/tcpsocket_init" if Gem.configuration.ipv4_fallback_enabled
      require_relative "vendored_net_http"
      require_relative "vendor/uri/lib/uri"

      Socket.do_not_reverse_lookup = true

      @proxy = proxy
      @pools = {}
      @pool_lock = Thread::Mutex.new
      @cert_files = Gem::Request.get_cert_files

      @headers = headers
    end

Initialize a remote fetcher using the source `URI` and possible proxy information.

`proxy`

- [String]: explicit specification of proxy; overrides any environment

      variable setting

- nil: respect environment variables (HTTP_PROXY, HTTP_PROXY_USER,

      HTTP_PROXY_PASS)

- `:no_proxy`: ignore environment variables and _don’t_ use a proxy

`headers`: A set of additional HTTP headers to be sent to the server when

    fetching the gem.

### Public Instance Methods

cache_update_path (uri, path = nil, update = true)
Source

    # File lib/rubygems/remote_fetcher.rb, line 286
    def cache_update_path(uri, path = nil, update = true)
      mtime = begin
                path && File.stat(path).mtime
              rescue StandardError
                nil
              end

      data = fetch_path(uri, mtime)

      if data.nil? # indicates the server returned 304 Not Modified
        return Gem.read_binary(path)
      end

      if update && path
        Gem.write_binary(path, data)
      end

      data
    end

Downloads `uri` to `path` if necessary. If no path is given, it just passes the data.

close_all ()
Source

    # File lib/rubygems/remote_fetcher.rb, line 326
    def close_all
      @pools.each_value(&:close_all)
    end

download (spec, source_uri, install_dir = Gem.dir)
Source

    # File lib/rubygems/remote_fetcher.rb, line 112
    def download(spec, source_uri, install_dir = Gem.dir)
      install_cache_dir = File.join install_dir, "cache"
      cache_dir =
        if Dir.pwd == install_dir # see fetch_command
          install_dir
        elsif File.writable?(install_cache_dir) || (File.writable?(install_dir) && !File.exist?(install_cache_dir))
          install_cache_dir
        else
          File.join Gem.user_dir, "cache"
        end

      gem_file_name = File.basename spec.cache_file
      local_gem_path = File.join cache_dir, gem_file_name

      require "fileutils"
      begin
        FileUtils.mkdir_p cache_dir
      rescue StandardError
        nil
      end unless File.exist? cache_dir

      source_uri = Gem::Uri.new(source_uri)

      scheme = source_uri.scheme

      # Gem::URI.parse gets confused by MS Windows paths with forward slashes.
      scheme = nil if /^[a-z]$/i.match?(scheme)

      # REFACTOR: split this up and dispatch on scheme (eg download_http)
      # REFACTOR: be sure to clean up fake fetcher when you do this... cleaner
      case scheme
      when "http", "https", "s3" then
        unless File.exist? local_gem_path
          begin
            verbose "Downloading gem #{gem_file_name}"

            remote_gem_path = source_uri + "gems/#{gem_file_name}"

            cache_update_path remote_gem_path, local_gem_path
          rescue FetchError
            raise if spec.original_platform == spec.platform

            alternate_name = "#{spec.original_name}.gem"

            verbose "Failed, downloading gem #{alternate_name}"

            remote_gem_path = source_uri + "gems/#{alternate_name}"

            cache_update_path remote_gem_path, local_gem_path
          end
        end
      when "file" then
        begin
          path = source_uri.path
          path = File.dirname(path) if File.extname(path) == ".gem"

          remote_gem_path = Gem::Util.correct_for_windows_path(File.join(path, "gems", gem_file_name))

          FileUtils.cp(remote_gem_path, local_gem_path)
        rescue Errno::EACCES
          local_gem_path = source_uri.to_s
        end

        verbose "Using local gem #{local_gem_path}"
      when nil then # TODO: test for local overriding cache
        source_path = if Gem.win_platform? && source_uri.scheme &&
                         !source_uri.path.include?(":")
          "#{source_uri.scheme}:#{source_uri.path}"
        else
          source_uri.path
        end

        source_path = Gem::UriFormatter.new(source_path).unescape

        begin
          FileUtils.cp source_path, local_gem_path unless
            File.identical?(source_path, local_gem_path)
        rescue Errno::EACCES
          local_gem_path = source_uri.to_s
        end

        verbose "Using local gem #{local_gem_path}"
      else
        raise ArgumentError, "unsupported URI scheme #{source_uri.scheme}"
      end

      local_gem_path
    end

Moves the gem `spec` from `source_uri` to the cache dir unless it is already there. If the source_uri is local the gem cache dir copy is always replaced.

download_to_cache (dependency)
Source

    # File lib/rubygems/remote_fetcher.rb, line 97
    def download_to_cache(dependency)
      found, _ = Gem::SpecFetcher.fetcher.spec_for_dependency dependency

      return if found.empty?

      spec, source = found.max_by {|(s,_)| s.version }

      download spec, source.uri
    end

Given a name and requirement, downloads this gem into cache and returns the filename. Returns nil if the gem cannot be located.

fetch_file (uri, *_)
Source

    # File lib/rubygems/remote_fetcher.rb, line 204
    def fetch_file(uri, *_)
      Gem.read_binary Gem::Util.correct_for_windows_path uri.path
    end

`File` Fetcher. Dispatched by `fetch_path`. Use it instead.

fetch_http (uri, last_modified = nil, head = false, depth = 0)
Source

    # File lib/rubygems/remote_fetcher.rb, line 211
    def fetch_http(uri, last_modified = nil, head = false, depth = 0)
      fetch_type = head ? Gem::Net::HTTP::Head : Gem::Net::HTTP::Get
      response   = request uri, fetch_type, last_modified do |req|
        headers.each {|k,v| req.add_field(k,v) }
      end

      case response
      when Gem::Net::HTTPOK, Gem::Net::HTTPNotModified then
        response.uri = uri
        head ? response : response.body
      when Gem::Net::HTTPMovedPermanently, Gem::Net::HTTPFound, Gem::Net::HTTPSeeOther,
           Gem::Net::HTTPTemporaryRedirect then
        raise FetchError.new("too many redirects", uri) if depth > 10

        unless location = response["Location"]
          raise FetchError.new("redirecting but no redirect location was given", uri)
        end
        location = Gem::Uri.new location

        if https?(uri) && !https?(location)
          raise FetchError.new("redirecting to non-https resource: #{location}", uri)
        end

        fetch_http(location, last_modified, head, depth + 1)
      else
        raise FetchError.new("bad response #{response.message} #{response.code}", uri)
      end
    end

HTTP Fetcher. Dispatched by `fetch_path`. Use it instead.

Also aliased as: fetch_https
fetch_https (uri, last_modified = nil, head = false, depth = 0)
Alias for: fetch_http
fetch_path (uri, mtime = nil, head = false)
Source

    # File lib/rubygems/remote_fetcher.rb, line 245
    def fetch_path(uri, mtime = nil, head = false)
      uri = Gem::Uri.new uri

      unless uri.scheme
        raise ArgumentError, "uri scheme is invalid: #{uri.scheme.inspect}"
      end

      data = send "fetch_#{uri.scheme}", uri, mtime, head

      if data && !head && uri.to_s.end_with?(".gz")
        begin
          data = Gem::Util.gunzip data
        rescue Zlib::GzipFile::Error
          raise FetchError.new("server did not return a valid file", uri)
        end
      end

      data
    rescue Gem::Timeout::Error, IOError, SocketError, SystemCallError,
           *(OpenSSL::SSL::SSLError if Gem::HAVE_OPENSSL) => e
      raise FetchError.new("#{e.class}: #{e}", uri)
    end

Downloads `uri` and returns it as a `String`.

fetch_s3 (uri, mtime = nil, head = false)
Source

    # File lib/rubygems/remote_fetcher.rb, line 268
    def fetch_s3(uri, mtime = nil, head = false)
      begin
        public_uri = s3_uri_signer(uri).sign
      rescue Gem::S3URISigner::ConfigurationError, Gem::S3URISigner::InstanceProfileError => e
        raise FetchError.new(e.message, "s3://#{uri.host}")
      end
      fetch_https public_uri, mtime, head
    end

https? (uri)
Source

    # File lib/rubygems/remote_fetcher.rb, line 322
    def https?(uri)
      uri.scheme.casecmp("https").zero?
    end

request (uri, request_class, last_modified = nil) { |req| ... }
Source

    # File lib/rubygems/remote_fetcher.rb, line 311
    def request(uri, request_class, last_modified = nil)
      proxy = proxy_for @proxy, uri
      pool  = pools_for(proxy).pool_for uri

      request = Gem::Request.new uri, request_class, last_modified, pool

      request.fetch do |req|
        yield req if block_given?
      end
    end

Performs a Gem::Net::HTTP request of type `request_class` on `uri` returning a Gem::Net::HTTP response object. request maintains a table of persistent connections to reduce connect overhead.

s3_uri_signer (uri)
Source

    # File lib/rubygems/remote_fetcher.rb, line 278
    def s3_uri_signer(uri)
      Gem::S3URISigner.new(uri)
    end

we have our own signing code here to avoid a dependency on the aws-sdk gem

### Private Instance Methods

pools_for (proxy)
Source

    # File lib/rubygems/remote_fetcher.rb, line 336
    def pools_for(proxy)
      @pool_lock.synchronize do
        @pools[proxy] ||= Gem::Request::ConnectionPools.new proxy, @cert_files
      end
    end

proxy_for (proxy, uri)
Source

    # File lib/rubygems/remote_fetcher.rb, line 332
    def proxy_for(proxy, uri)
      Gem::Request.proxy_uri(proxy || Gem::Request.get_proxy_from_env(uri.scheme))
    end