Added support for Accept-Encoding (via Request#accept_encoding and Utils.select_best_encoding)

4 files changed, 81 insertions, 0 deletions

diff --git a/lib/rack/request.rb b/lib/rack/request.rb
index 68c11198..2a9bcc15 100644
--- a/lib/rack/request.rb
+++ b/lib/rack/request.rb
@@ -193,5 +193,17 @@ module Rack
       path << "?" << query_string  unless query_string.empty?
       path
     end
+
+    def accept_encoding
+      @env["HTTP_ACCEPT_ENCODING"].to_s.split(/,\s*/).map do |part|
+        m = /^([^\s,]+?)(?:;\s*q=(\d+(?:\.\d+)?))?$/.match(part) # From WEBrick
+
+        if m
+          [m[1], (m[2] || 1.0).to_f]
+        else
+          raise "Invalid value for Accept-Encoding: #{part.inspect}"
+        end
+      end
+    end
   end
 end
diff --git a/lib/rack/utils.rb b/lib/rack/utils.rb
index 4329b988..25254bbd 100644
--- a/lib/rack/utils.rb
+++ b/lib/rack/utils.rb
@@ -71,6 +71,36 @@ module Rack
     end
     module_function :escape_html
 
+    def select_best_encoding(available_encodings, accept_encoding)
+      # http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
+
+      expanded_accept_encoding =
+        accept_encoding.map { |m, q|
+          if m == "*"
+            (available_encodings - accept_encoding.map { |m2, _| m2 }).map { |m2| [m2, q] }
+          else
+            [[m, q]]
+          end
+        }.inject([]) { |mem, list|
+          mem + list
+        }
+
+      encoding_candidates = expanded_accept_encoding.sort_by { |_, q| -q }.map { |m, _| m }
+
+      unless encoding_candidates.include?("identity")
+        encoding_candidates.push("identity")
+      end
+
+      expanded_accept_encoding.find_all { |m, q|
+        q == 0.0
+      }.each { |m, _|
+        encoding_candidates.delete(m)
+      }
+
+      return (encoding_candidates & available_encodings)[0]
+    end
+    module_function :select_best_encoding
+
     # The recommended manner in which to implement a contexting application
     # is to define a method #context in which a new Context is instantiated.
     #
diff --git a/test/spec_rack_request.rb b/test/spec_rack_request.rb
index 4321516e..2b30ff3f 100644
--- a/test/spec_rack_request.rb
+++ b/test/spec_rack_request.rb
@@ -381,4 +381,20 @@ EOF
 
     res.should.be.ok
   end
+
+  specify "should parse Accept-Encoding correctly" do
+    parser = lambda do |x|
+      Rack::Request.new(Rack::MockRequest.env_for("", "HTTP_ACCEPT_ENCODING" => x)).accept_encoding
+    end
+
+    parser.call(nil).should.equal([])
+
+    parser.call("compress, gzip").should.equal([["compress", 1.0], ["gzip", 1.0]])
+    parser.call("").should.equal([])
+    parser.call("*").should.equal([["*", 1.0]])
+    parser.call("compress;q=0.5, gzip;q=1.0").should.equal([["compress", 0.5], ["gzip", 1.0]])
+    parser.call("gzip;q=1.0, identity; q=0.5, *;q=0").should.equal([["gzip", 1.0], ["identity", 0.5], ["*", 0] ])
+
+    lambda { parser.call("gzip ; q=1.0") }.should.raise(RuntimeError)
+  end
 end
diff --git a/test/spec_rack_utils.rb b/test/spec_rack_utils.rb
index 8256e12f..6e253c43 100644
--- a/test/spec_rack_utils.rb
+++ b/test/spec_rack_utils.rb
@@ -39,6 +39,29 @@ context "Rack::Utils" do
     Rack::Utils.build_query("my weird field" => "q1!2\"'w$5&7/z8)?").
       should.equal "my+weird+field=q1%212%22%27w%245%267%2Fz8%29%3F"
   end
+
+  specify "should figure out which encodings are acceptable" do
+    helper = lambda do |a, b|
+      request = Rack::Request.new(Rack::MockRequest.env_for("", "HTTP_ACCEPT_ENCODING" => a))
+      Rack::Utils.select_best_encoding(a, b)
+    end
+
+    helper.call(%w(), [["x", 1]]).should.equal(nil)
+    helper.call(%w(identity), [["identity", 0.0]]).should.equal(nil)
+    helper.call(%w(identity), [["*", 0.0]]).should.equal(nil)
+
+    helper.call(%w(identity), [["compress", 1.0], ["gzip", 1.0]]).should.equal("identity")
+
+    helper.call(%w(compress gzip identity), [["compress", 1.0], ["gzip", 1.0]]).should.equal("compress")
+    helper.call(%w(compress gzip identity), [["compress", 0.5], ["gzip", 1.0]]).should.equal("gzip")
+
+    helper.call(%w(foo bar identity), []).should.equal("identity")
+    helper.call(%w(foo bar identity), [["*", 1.0]]).should.equal("foo")
+    helper.call(%w(foo bar identity), [["*", 1.0], ["foo", 0.9]]).should.equal("bar")
+
+    helper.call(%w(foo bar identity), [["foo", 0], ["bar", 0]]).should.equal("identity")
+    helper.call(%w(foo bar baz identity), [["*", 0], ["identity", 0.1]]).should.equal("identity")
+  end
 end
 
 context "Rack::Utils::HeaderHash" do