[Http] add default User-Agent string to cURL requests, unless one is …

…provided by :headers

CHANGELOG.md

@@ -4,7 +4,9 @@
 
 ##### Enhancements
 
-* None.  
+* Add User-Agent to `cURL` requests when downloading source via the `:http` download strategy, unless one was provided by the `:headers` option.  
+  [Sean Reinhardt](https://github.com/seanreinhardtapps)
+  [#9619](https://github.com/CocoaPods/CocoaPods/issues/9619)
 
 ##### Bug Fixes
 

lib/cocoapods-downloader/base.rb

@@ -121,6 +121,18 @@ def checkout_options
         raise 'Abstract method'
       end
 
+      # Returns a User-Agent string that itentifies http network requests as
+      # originating from CocoaPods.
+      # Contains version numbers from the CocoaPods Gem and the cocoapods-downloader Gem.
+      #
+      # @param  [module] base_module The Base CocoaPods Module to retrieve the version number from.
+      # @return [String] the User-Agent string.
+      #
+      def self.user_agent_string(base_module = Pod)
+        pods_version = base_module.const_defined?('VERSION') ? "CocoaPods/#{base_module::VERSION} " : ''
+        "#{pods_version}cocoapods-downloader/#{Pod::Downloader::VERSION}"
+      end
+
       #-----------------------------------------------------------------------#
 
       # Defines two methods for an executable, based on its name. The bang

lib/cocoapods-downloader/http.rb

@@ -3,12 +3,16 @@
 module Pod
   module Downloader
     class Http < RemoteFile
+      USER_AGENT_HEADER = 'User-Agent'.freeze
+
       private
 
       executable :curl
 
       def download_file(full_filename)
         parameters = ['-f', '-L', '-o', full_filename, url, '--create-dirs', '--netrc-optional', '--retry', '2']
+        parameters << user_agent_argument if headers.nil? ||
+            headers.none? { |header| header.casecmp(USER_AGENT_HEADER).zero? }
 
         headers.each do |h|
           parameters << '-H'
@@ -17,6 +21,14 @@ def download_file(full_filename)
 
         curl! parameters
       end
+
+      # Returns a cURL command flag to add the CocoaPods User-Agent.
+      #
+      # @return [String] cURL command -A flag and User-Agent.
+      #
+      def user_agent_argument
+        "-A '#{Http.user_agent_string}'"
+      end
     end
   end
 end

spec/base_spec.rb

@@ -14,6 +14,20 @@ module Downloader
         new_options = Base.preprocess_options(options)
         new_options.should == options
       end
+
+      it 'defines a user agent with the cocoapods-downloader version' do
+        module TestModuleNoVersion
+        end
+        Base.user_agent_string(TestModuleNoVersion).should == "cocoapods-downloader/#{Pod::Downloader::VERSION}"
+      end
+
+      it 'defines a user agent containing CocoaPods downloader versions when available' do
+        module TestModuleWithVersion
+          VERSION = 'a.b.c'.freeze
+        end
+        Base.user_agent_string(TestModuleWithVersion).should ==
+          "CocoaPods/#{TestModuleWithVersion::VERSION} cocoapods-downloader/#{Pod::Downloader::VERSION}"
+      end
     end
   end
 end

spec/http_spec.rb

@@ -3,9 +3,11 @@
 module Pod
   module Downloader
     describe 'HTTP' do
+      mock_user_agent = 'mock_user_agent'.freeze
       before do
         tmp_folder.rmtree if tmp_folder.exist?
         @fixtures_url = 'file://' + fixture('http').to_s
+        Http.stubs(:user_agent_string).returns(mock_user_agent)
       end
 
       it 'download file and unzip it' do
@@ -75,6 +77,78 @@ module Downloader
           downloader.download
         end
       end
+
+      it 'passes User-Agent to cURL' do
+        options = { :http => "#{@fixtures_url}/lib.zip" }
+        downloader = Downloader.for_target(tmp_folder, options)
+        downloader.expects(:curl!).with(
+          includes("-A \'#{mock_user_agent}\'"),
+        )
+        should.raise DownloaderError do
+          downloader.download
+        end
+      end
+
+      it 'passes default User-Agent to cURL with other request headers' do
+        options = { :http => "#{@fixtures_url}/lib.zip",
+                    :headers => ['Accept: application/json'],
+         }
+        downloader = Downloader.for_target(tmp_folder, options)
+        downloader.expects(:curl!).with(
+          includes("-A \'#{mock_user_agent}\'"),
+        )
+        should.raise DownloaderError do
+          downloader.download
+        end
+      end
+
+      it 'prefers User-Agent provided in headers over default User-Agent' do
+        options = {
+          :http => "#{@fixtures_url}/lib.zip",
+          :headers => ['Accept: application/json', 'User-Agent: custom_user_agent'],
+        }
+        downloader = Downloader.for_target(tmp_folder, options)
+        downloader.expects(:curl!).with(
+          all_of(
+            includes('-H'),
+            includes('Accept: application/json'),
+            includes('-H'),
+            includes('User-Agent: custom_user_agent'),
+          ),
+          Not(
+            includes("-A \'#{mock_user_agent}\'"),
+          ),
+        )
+        should.raise DownloaderError do
+          downloader.download
+        end
+      end
+
+      it 'prefers case insensitive User-Agent provided in headers' do
+        options = {
+          :http => "#{@fixtures_url}/lib.zip",
+          :headers => ['Accept: application/json', 'user-agent: custom_user_agent'],
+        }
+        downloader = Downloader.for_target(tmp_folder, options)
+        downloader.expects(:curl!).with(
+          all_of(
+            includes('-H'),
+            includes('Accept: application/json'),
+            includes('-H'),
+            includes('user-agent: custom_user_agent'),
+          ),
+          Not(
+            includes("-A \'#{mock_user_agent}\'"),
+          ),
+        )
+        should.raise DownloaderError do
+          downloader.download
+        end
+      end
+
+      it 'supplies User-Agent argument for cURL' do
+        Http.new('', '', {}).instance_eval { user_agent_argument }.should.match /-A '#{mock_user_agent}'/
+      end
     end
   end
 end

spec/remote_file_spec.rb

@@ -14,6 +14,7 @@ def download_file(full_filename)
       before do
         tmp_folder.rmtree if tmp_folder.exist?
         @fixtures_url = 'file://' + fixture('remote_file').to_s
+        RemoteFile.stubs(:user_agent_string).returns('mock_user_agent')
       end
 
       it 'download file and unzip it' do