Handle Encoded Downloads

nebhale · nebhale · commit a3caeff96e0d · 2016-03-21T09:02:04.000-07:00
Previously, all downloads passed through DownloadCache required that the value
of the Content-Length header matched the size of the file that was actually
downloaded. This did not take into account compressed encoding schemes for the
artifacts and would fail when they were compressed.  This change detects when
an artifact is compressed and skips the  size validation.

[#116036875]
diff --git a/lib/java_buildpack/util/cache/download_cache.rb b/lib/java_buildpack/util/cache/download_cache.rb
@@ -144,6 +144,8 @@ def attempt(http, request, cached_file)
         end
 
         def cache_content(response, cached_file)
+          compressed = compressed?(response)
+
           cached_file.cached(File::CREAT | File::WRONLY | File::BINARY) do |f|
             @logger.debug { "Persisting content to #{f.path}" }
 
@@ -152,7 +154,7 @@ def cache_content(response, cached_file)
             f.fsync
           end
 
-          validate_size response['Content-Length'], cached_file
+          validate_size response['Content-Length'], cached_file unless compressed
         end
 
         def cache_etag(response, cached_file)
@@ -183,6 +185,10 @@ def cache_last_modified(response, cached_file)
           end
         end
 
+        def compressed?(response)
+          %w(br compress deflate gzip x-gzip).include?(response['Content-Encoding'])
+        end
+
         def debug_ssl(http)
           socket = http.instance_variable_get('@socket')
           return unless socket
@@ -300,7 +306,7 @@ def validate_size(expected_size, cached_file)
           actual_size = cached_file.cached(File::RDONLY) { |f| f.size }
           @logger.debug { "Validated content size #{actual_size} is #{expected_size}" }
 
-          return if expected_size.to_i == actual_size
+          return if (expected_size.to_i == actual_size)
 
           cached_file.destroy
           fail InferredNetworkFailure, "Content has invalid size.  Was #{actual_size}, should be #{expected_size}."
diff --git a/spec/java_buildpack/util/cache/download_cache_spec.rb b/spec/java_buildpack/util/cache/download_cache_spec.rb
@@ -170,6 +170,18 @@
     expect { |b| download_cache.get uri, &b }.to yield_file_with_content(/foo-cached/)
   end
 
+  it 'ignores incorrect size when encoded' do
+    stub_request(:get, uri)
+      .to_return(status: 200, body: 'foo-cac', headers: { Etag:              'foo-etag',
+                                                          'Content-Encoding' => 'gzip',
+                                                          'Last-Modified'    => 'foo-last-modified',
+                                                          'Content-Length'   => 10 })
+
+    touch immutable_cache_root, 'cached', 'old-foo-cached'
+
+    expect { |b| download_cache.get uri, &b }.to yield_file_with_content(/foo-cac/)
+  end
+
   context do
 
     let(:environment) { { 'http_proxy' => 'http://proxy:9000', 'HTTP_PROXY' => nil } }
