14 files changed, 62 insertions, 41 deletions
diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index dd91038d64..c27ce896c8 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -844,7 +844,7 @@ module Bundler
       return unless SharedHelpers.md5_available?
 
       latest = Fetcher::CompactIndex.
-               new(nil, Source::Rubygems::Remote.new(Bundler::URI("https://rubygems.org")), nil).
+               new(nil, Source::Rubygems::Remote.new(Bundler::URI("https://rubygems.org")), nil, nil).
                send(:compact_index_client).
                instance_variable_get(:@cache).
                dependencies("bundler").
diff --git a/lib/bundler/fetcher.rb b/lib/bundler/fetcher.rb
index e5384c5679..dd91b7ceb4 100644
--- a/lib/bundler/fetcher.rb
+++ b/lib/bundler/fetcher.rb
@@ -204,6 +204,16 @@ module Bundler
       fetchers.first.api_fetcher?
     end
 
+    def gem_remote_fetcher
+      @gem_remote_fetcher ||= begin
+        require_relative "fetcher/gem_remote_fetcher"
+        fetcher = GemRemoteFetcher.new Gem.configuration[:http_proxy]
+        fetcher.headers["User-Agent"] = user_agent
+        fetcher.headers["X-Gemfile-Source"] = @remote.original_uri.to_s if @remote.original_uri
+        fetcher
+      end
+    end
+
     private
 
     def available_fetchers
@@ -218,7 +228,7 @@ module Bundler
     end
 
     def fetchers
-      @fetchers ||= available_fetchers.map {|f| f.new(downloader, @remote, uri) }.drop_while {|f| !f.available? }
+      @fetchers ||= available_fetchers.map {|f| f.new(downloader, @remote, uri, gem_remote_fetcher) }.drop_while {|f| !f.available? }
     end
 
     def fetch_specs(gem_names)
diff --git a/lib/bundler/fetcher/base.rb b/lib/bundler/fetcher/base.rb
index 99c6343c9a..cfec2f8e94 100644
--- a/lib/bundler/fetcher/base.rb
+++ b/lib/bundler/fetcher/base.rb
@@ -6,12 +6,14 @@ module Bundler
       attr_reader :downloader
       attr_reader :display_uri
       attr_reader :remote
+      attr_reader :gem_remote_fetcher
 
-      def initialize(downloader, remote, display_uri)
+      def initialize(downloader, remote, display_uri, gem_remote_fetcher)
         raise "Abstract class" if self.class == Base
         @downloader = downloader
         @remote = remote
         @display_uri = display_uri
+        @gem_remote_fetcher = gem_remote_fetcher
       end
 
       def remote_uri
diff --git a/lib/bundler/fetcher/gem_remote_fetcher.rb b/lib/bundler/fetcher/gem_remote_fetcher.rb
new file mode 100644
index 0000000000..3fc7b68263
--- /dev/null
+++ b/lib/bundler/fetcher/gem_remote_fetcher.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+require "rubygems/remote_fetcher"
+
+module Bundler
+  class Fetcher
+    class GemRemoteFetcher < Gem::RemoteFetcher
+      def request(*args)
+        super do |req|
+          req.delete("User-Agent") if headers["User-Agent"]
+          yield req if block_given?
+        end
+      end
+    end
+  end
+end
diff --git a/lib/bundler/fetcher/index.rb b/lib/bundler/fetcher/index.rb
index c623647f01..6e37e1e5d1 100644
--- a/lib/bundler/fetcher/index.rb
+++ b/lib/bundler/fetcher/index.rb
@@ -6,7 +6,7 @@ module Bundler
   class Fetcher
     class Index < Base
       def specs(_gem_names)
-        Bundler.rubygems.fetch_all_remote_specs(remote)
+        Bundler.rubygems.fetch_all_remote_specs(remote, gem_remote_fetcher)
       rescue Gem::RemoteFetcher::FetchError => e
         case e.message
         when /certificate verify failed/
diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
index f420934ceb..bde2b39416 100644
--- a/lib/bundler/rubygems_integration.rb
+++ b/lib/bundler/rubygems_integration.rb
@@ -467,11 +467,9 @@ module Bundler
       Gem::Specification.all = specs
     end
 
-    def fetch_specs(remote, name)
+    def fetch_specs(remote, name, fetcher)
       require "rubygems/remote_fetcher"
       path = remote.uri.to_s + "#{name}.#{Gem.marshal_version}.gz"
-      fetcher = gem_remote_fetcher
-      fetcher.headers = { "X-Gemfile-Source" => remote.original_uri.to_s } if remote.original_uri
       string = fetcher.fetch_path(path)
       specs = Bundler.safe_load_marshal(string)
       raise MarshalError, "Specs #{name} from #{remote} is expected to be an Array but was unexpected class #{specs.class}" unless specs.is_a?(Array)
@@ -481,18 +479,16 @@ module Bundler
       raise unless name == "prerelease_specs"
     end
 
-    def fetch_all_remote_specs(remote)
-      specs = fetch_specs(remote, "specs")
-      pres = fetch_specs(remote, "prerelease_specs") || []
+    def fetch_all_remote_specs(remote, gem_remote_fetcher)
+      specs = fetch_specs(remote, "specs", gem_remote_fetcher)
+      pres = fetch_specs(remote, "prerelease_specs", gem_remote_fetcher) || []
 
       specs.concat(pres)
     end
 
-    def download_gem(spec, uri, cache_dir)
+    def download_gem(spec, uri, cache_dir, fetcher)
       require "rubygems/remote_fetcher"
       uri = Bundler.settings.mirror_for(uri)
-      fetcher = gem_remote_fetcher
-      fetcher.headers = { "X-Gemfile-Source" => spec.remote.original_uri.to_s } if spec.remote.original_uri
       Bundler::Retry.new("download gem from #{uri}").attempts do
         gem_file_name = spec.file_name
         local_gem_path = File.join cache_dir, gem_file_name
@@ -519,11 +515,6 @@ module Bundler
       raise Bundler::HTTPError, "Could not download gem from #{uri} due to underlying error <#{e.message}>"
     end
 
-    def gem_remote_fetcher
-      require "rubygems/remote_fetcher"
-      Gem::RemoteFetcher.fetcher
-    end
-
     def build(spec, skip_validation = false)
       require "rubygems/package"
       Gem::Package.build(spec, skip_validation)
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
index 6d6f36e298..e67e7a97ff 100644
--- a/lib/bundler/source/rubygems.rb
+++ b/lib/bundler/source/rubygems.rb
@@ -255,11 +255,15 @@ module Bundler
         end
       end
 
-      def fetchers
-        @fetchers ||= remotes.map do |uri|
+      def remote_fetchers
+        @remote_fetchers ||= remotes.to_h do |uri|
           remote = Source::Rubygems::Remote.new(uri)
-          Bundler::Fetcher.new(remote)
-        end
+          [remote, Bundler::Fetcher.new(remote)]
+        end.freeze
+      end
+
+      def fetchers
+        @fetchers ||= remote_fetchers.values.freeze
       end
 
       def double_check_for(unmet_dependency_names)
@@ -480,7 +484,8 @@ module Bundler
       def download_gem(spec, download_cache_path, previous_spec = nil)
         uri = spec.remote.uri
         Bundler.ui.confirm("Fetching #{version_message(spec, previous_spec)}")
-        Bundler.rubygems.download_gem(spec, uri, download_cache_path)
+        gem_remote_fetcher = remote_fetchers.fetch(spec.remote).gem_remote_fetcher
+        Bundler.rubygems.download_gem(spec, uri, download_cache_path, gem_remote_fetcher)
       end
 
       # Returns the global cache path of the calling Rubygems::Source object.
diff --git a/spec/bundler/bundler/fetcher/base_spec.rb b/spec/bundler/bundler/fetcher/base_spec.rb
index 02506591f3..fa1021ecf7 100644
--- a/spec/bundler/bundler/fetcher/base_spec.rb
+++ b/spec/bundler/bundler/fetcher/base_spec.rb
@@ -4,15 +4,16 @@ RSpec.describe Bundler::Fetcher::Base do
   let(:downloader)  { double(:downloader) }
   let(:remote)      { double(:remote) }
   let(:display_uri) { "http://sample_uri.com" }
+  let(:gem_remote_fetcher) { nil }
 
   class TestClass < described_class; end
 
-  subject { TestClass.new(downloader, remote, display_uri) }
+  subject { TestClass.new(downloader, remote, display_uri, gem_remote_fetcher) }
 
   describe "#initialize" do
     context "with the abstract Base class" do
       it "should raise an error" do
-        expect { described_class.new(downloader, remote, display_uri) }.to raise_error(RuntimeError, "Abstract class")
+        expect { described_class.new(downloader, remote, display_uri, gem_remote_fetcher) }.to raise_error(RuntimeError, "Abstract class")
       end
     end
 
diff --git a/spec/bundler/bundler/fetcher/compact_index_spec.rb b/spec/bundler/bundler/fetcher/compact_index_spec.rb
index 00eb27edea..d17889f8d6 100644
--- a/spec/bundler/bundler/fetcher/compact_index_spec.rb
+++ b/spec/bundler/bundler/fetcher/compact_index_spec.rb
@@ -7,7 +7,8 @@ RSpec.describe Bundler::Fetcher::CompactIndex do
   let(:downloader)  { double(:downloader) }
   let(:display_uri) { Bundler::URI("http://sampleuri.com") }
   let(:remote)      { double(:remote, :cache_slug => "lsjdf", :uri => display_uri) }
-  let(:compact_index) { described_class.new(downloader, remote, display_uri) }
+  let(:gem_remote_fetcher) { nil }
+  let(:compact_index) { described_class.new(downloader, remote, display_uri, gem_remote_fetcher) }
 
   before do
     allow(compact_index).to receive(:log_specs) {}
diff --git a/spec/bundler/bundler/fetcher/dependency_spec.rb b/spec/bundler/bundler/fetcher/dependency_spec.rb
index 20307f9c99..2db31b1846 100644
--- a/spec/bundler/bundler/fetcher/dependency_spec.rb
+++ b/spec/bundler/bundler/fetcher/dependency_spec.rb
@@ -4,8 +4,9 @@ RSpec.describe Bundler::Fetcher::Dependency do
   let(:downloader)  { double(:downloader) }
   let(:remote)      { double(:remote, :uri => Bundler::URI("http://localhost:5000")) }
   let(:display_uri) { "http://sample_uri.com" }
+  let(:gem_remote_fetcher) { nil }
 
-  subject { described_class.new(downloader, remote, display_uri) }
+  subject { described_class.new(downloader, remote, display_uri, gem_remote_fetcher) }
 
   describe "#available?" do
     let(:dependency_api_uri) { double(:dependency_api_uri) }
diff --git a/spec/bundler/bundler/fetcher/index_spec.rb b/spec/bundler/bundler/fetcher/index_spec.rb
index 971b64ce8f..f3cdc235ba 100644
--- a/spec/bundler/bundler/fetcher/index_spec.rb
+++ b/spec/bundler/bundler/fetcher/index_spec.rb
@@ -8,8 +8,9 @@ RSpec.describe Bundler::Fetcher::Index do
   let(:display_uri) { "http://sample_uri.com" }
   let(:rubygems)    { double(:rubygems) }
   let(:gem_names)   { %w[foo bar] }
+  let(:gem_remote_fetcher) { nil }
 
-  subject { described_class.new(downloader, remote, display_uri) }
+  subject { described_class.new(downloader, remote, display_uri, gem_remote_fetcher) }
 
   before { allow(Bundler).to receive(:rubygems).and_return(rubygems) }
 
diff --git a/spec/bundler/bundler/rubygems_integration_spec.rb b/spec/bundler/bundler/rubygems_integration_spec.rb
index 182aa3646a..b10e8ac6b5 100644
--- a/spec/bundler/bundler/rubygems_integration_spec.rb
+++ b/spec/bundler/bundler/rubygems_integration_spec.rb
@@ -46,14 +46,12 @@ RSpec.describe Bundler::RubygemsIntegration do
     let(:fetcher) { double("gem_remote_fetcher") }
 
     it "successfully downloads gem with retries" do
-      expect(Bundler.rubygems).to receive(:gem_remote_fetcher).and_return(fetcher)
-      expect(fetcher).to receive(:headers=).with({ "X-Gemfile-Source" => "https://foo.bar" })
       expect(Bundler::Retry).to receive(:new).with("download gem from #{uri}/").
         and_return(bundler_retry)
       expect(bundler_retry).to receive(:attempts).and_yield
       expect(fetcher).to receive(:cache_update_path)
 
-      Bundler.rubygems.download_gem(spec, uri, cache_dir)
+      Bundler.rubygems.download_gem(spec, uri, cache_dir, fetcher)
     end
   end
 
@@ -68,11 +66,9 @@ RSpec.describe Bundler::RubygemsIntegration do
       let(:remote_with_mirror) { double("remote", :uri => uri, :original_uri => orig_uri) }
 
       it "sets the 'X-Gemfile-Source' header containing the original source" do
-        expect(Bundler.rubygems).to receive(:gem_remote_fetcher).twice.and_return(fetcher)
-        expect(fetcher).to receive(:headers=).with({ "X-Gemfile-Source" => "http://zombo.com" }).twice
         expect(fetcher).to receive(:fetch_path).with(uri + "specs.4.8.gz").and_return(specs_response)
         expect(fetcher).to receive(:fetch_path).with(uri + "prerelease_specs.4.8.gz").and_return(prerelease_specs_response)
-        result = Bundler.rubygems.fetch_all_remote_specs(remote_with_mirror)
+        result = Bundler.rubygems.fetch_all_remote_specs(remote_with_mirror, fetcher)
         expect(result).to eq(%w[specs prerelease_specs])
       end
     end
@@ -81,11 +77,9 @@ RSpec.describe Bundler::RubygemsIntegration do
       let(:remote_no_mirror) { double("remote", :uri => uri, :original_uri => nil) }
 
       it "does not set the 'X-Gemfile-Source' header" do
-        expect(Bundler.rubygems).to receive(:gem_remote_fetcher).twice.and_return(fetcher)
-        expect(fetcher).to_not receive(:headers=)
         expect(fetcher).to receive(:fetch_path).with(uri + "specs.4.8.gz").and_return(specs_response)
         expect(fetcher).to receive(:fetch_path).with(uri + "prerelease_specs.4.8.gz").and_return(prerelease_specs_response)
-        result = Bundler.rubygems.fetch_all_remote_specs(remote_no_mirror)
+        result = Bundler.rubygems.fetch_all_remote_specs(remote_no_mirror, fetcher)
         expect(result).to eq(%w[specs prerelease_specs])
       end
     end
@@ -95,9 +89,8 @@ RSpec.describe Bundler::RubygemsIntegration do
       let(:unexpected_specs_response) { Marshal.dump(3) }
 
       it "raises a MarshalError error" do
-        expect(Bundler.rubygems).to receive(:gem_remote_fetcher).once.and_return(fetcher)
         expect(fetcher).to receive(:fetch_path).with(uri + "specs.4.8.gz").and_return(unexpected_specs_response)
-        expect { Bundler.rubygems.fetch_all_remote_specs(remote_no_mirror) }.to raise_error(Bundler::MarshalError, /unexpected class/i)
+        expect { Bundler.rubygems.fetch_all_remote_specs(remote_no_mirror, fetcher) }.to raise_error(Bundler::MarshalError, /unexpected class/i)
       end
     end
   end
diff --git a/spec/bundler/realworld/gemfile_source_header_spec.rb b/spec/bundler/realworld/gemfile_source_header_spec.rb
index 60c0055a62..ea909411ce 100644
--- a/spec/bundler/realworld/gemfile_source_header_spec.rb
+++ b/spec/bundler/realworld/gemfile_source_header_spec.rb
@@ -17,7 +17,7 @@ RSpec.describe "fetching dependencies with a mirrored source", :realworld => tru
     @t.join
   end
 
-  it "sets the 'X-Gemfile-Source' header and bundles successfully" do
+  it "sets the 'X-Gemfile-Source' and 'User-Agent' headers and bundles successfully" do
     gemfile <<-G
       source "#{mirror}"
       gem 'weakling'
diff --git a/spec/bundler/support/artifice/endpoint_mirror_source.rb b/spec/bundler/support/artifice/endpoint_mirror_source.rb
index 6ea1a77eca..fed7a746b9 100644
--- a/spec/bundler/support/artifice/endpoint_mirror_source.rb
+++ b/spec/bundler/support/artifice/endpoint_mirror_source.rb
@@ -4,7 +4,7 @@ require_relative "helpers/endpoint"
 
 class EndpointMirrorSource < Endpoint
   get "/gems/:id" do
-    if request.env["HTTP_X_GEMFILE_SOURCE"] == "https://server.example.org/"
+    if request.env["HTTP_X_GEMFILE_SOURCE"] == "https://server.example.org/" && request.env["HTTP_USER_AGENT"].start_with?("bundler")
       File.binread("#{gem_repo1}/gems/#{params[:id]}")
     else
       halt 500