[PATCH] deflater: always finish zlib stream before closing

[PATCH] deflater: always finish zlib stream before closing

[Eric Wong]

This helps avoid Zlib::DataError when a client disconnects on
the server while the server is writing the response.

This fixes the following backtraces on my server:

  data error (Zlib::DataError)
  rack/deflater.rb:124:in `close'
  rack/deflater.rb:124:in `ensure in each'
  rack/deflater.rb:124:in `each'
  rack/chunked.rb:23:in `each'
  ...
---
  If you prefer: git pull git://80x24.org/rack zlib-disco

  The following changes since commit c28f271d0c91f45e13bfa8f07bed445ef91f41de:

    Merge pull request #942 from keepcosmos/remove-fulltest-guide (2015-09-08 07:45:02 -0700)

  are available in the git repository at:

    git://80x24.org/rack zlib-disco

  for you to fetch changes up to f769efe714f5b8b417e0440ce05f8b4e4b504c57:

    deflater: always finish zlib stream before closing (2015-09-21 21:11:50 +0000)

  ----------------------------------------------------------------
  Eric Wong (1):
        deflater: always finish zlib stream before closing

 lib/rack/deflater.rb  |  3 ++-
 test/spec_deflater.rb | 25 +++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/lib/rack/deflater.rb b/lib/rack/deflater.rb
index 19dc755..62a1124 100644
--- a/lib/rack/deflater.rb
+++ b/lib/rack/deflater.rb
@@ -118,8 +118,9 @@ module Rack
       def each
         deflator = ::Zlib::Deflate.new(*DEFLATE_ARGS)
         @body.each { |part| yield deflator.deflate(part, Zlib::SYNC_FLUSH) }
-        yield deflator.finish
+        yield fin = deflator.finish
       ensure
+        deflator.finish unless fin
         deflator.close
       end
 
diff --git a/test/spec_deflater.rb b/test/spec_deflater.rb
index 2c7a428..ba7ec5d 100644
--- a/test/spec_deflater.rb
+++ b/test/spec_deflater.rb
@@ -114,6 +114,31 @@ describe Rack::Deflater do
     end
   end
 
+  it 'does not raise when a client aborts reading' do
+    app_body = Object.new
+    class << app_body; def each; yield('foo'); yield('bar'); end; end
+    opts = { 'skip_body_verify' => true }
+    verify(200, app_body, 'deflate', opts) do |status, headers, body|
+      headers.must_equal({
+        'Content-Encoding' => 'deflate',
+        'Vary' => 'Accept-Encoding',
+        'Content-Type' => 'text/plain'
+      })
+
+      buf = []
+      inflater = Zlib::Inflate.new(-Zlib::MAX_WBITS)
+      FakeDisconnect = Class.new(RuntimeError)
+      assert_raises(FakeDisconnect, "not Zlib::DataError not raised") do
+        body.each do |part|
+          buf << inflater.inflate(part)
+          raise FakeDisconnect
+        end
+      end
+      assert_raises(Zlib::BufError) { inflater.finish }
+      buf.must_equal(%w(foo))
+    end
+  end
+
   # TODO: This is really just a special case of the above...
   it 'be able to deflate String bodies' do
     verify(200, 'Hello world!', 'deflate') do |status, headers, body|
-- 
EW

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Re: [PATCH] deflater: always finish zlib stream before closing

[Aaron Patterson]

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Applied, thanks!

On Mon, Sep 21, 2015 at 09:16:15PM +0000, Eric Wong wrote:
> This helps avoid Zlib::DataError when a client disconnects on
> the server while the server is writing the response.
> 
> This fixes the following backtraces on my server:
> 
>   data error (Zlib::DataError)
>   rack/deflater.rb:124:in `close'
>   rack/deflater.rb:124:in `ensure in each'
>   rack/deflater.rb:124:in `each'
>   rack/chunked.rb:23:in `each'
>   ...
> ---
>   If you prefer: git pull git://80x24.org/rack zlib-disco
> 
>   The following changes since commit c28f271d0c91f45e13bfa8f07bed445ef91f41de:
> 
>     Merge pull request #942 from keepcosmos/remove-fulltest-guide (2015-09-08 07:45:02 -0700)
> 
>   are available in the git repository at:
> 
>     git://80x24.org/rack zlib-disco
> 
>   for you to fetch changes up to f769efe714f5b8b417e0440ce05f8b4e4b504c57:
> 
>     deflater: always finish zlib stream before closing (2015-09-21 21:11:50 +0000)
> 
>   ----------------------------------------------------------------
>   Eric Wong (1):
>         deflater: always finish zlib stream before closing
> 
>  lib/rack/deflater.rb  |  3 ++-
>  test/spec_deflater.rb | 25 +++++++++++++++++++++++++
>  2 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/rack/deflater.rb b/lib/rack/deflater.rb
> index 19dc755..62a1124 100644
> --- a/lib/rack/deflater.rb
> +++ b/lib/rack/deflater.rb
> @@ -118,8 +118,9 @@ module Rack
>        def each
>          deflator = ::Zlib::Deflate.new(*DEFLATE_ARGS)
>          @body.each { |part| yield deflator.deflate(part, Zlib::SYNC_FLUSH) }
> -        yield deflator.finish
> +        yield fin = deflator.finish
>        ensure
> +        deflator.finish unless fin
>          deflator.close
>        end
>  
> diff --git a/test/spec_deflater.rb b/test/spec_deflater.rb
> index 2c7a428..ba7ec5d 100644
> --- a/test/spec_deflater.rb
> +++ b/test/spec_deflater.rb
> @@ -114,6 +114,31 @@ describe Rack::Deflater do
>      end
>    end
>  
> +  it 'does not raise when a client aborts reading' do
> +    app_body = Object.new
> +    class << app_body; def each; yield('foo'); yield('bar'); end; end
> +    opts = { 'skip_body_verify' => true }
> +    verify(200, app_body, 'deflate', opts) do |status, headers, body|
> +      headers.must_equal({
> +        'Content-Encoding' => 'deflate',
> +        'Vary' => 'Accept-Encoding',
> +        'Content-Type' => 'text/plain'
> +      })
> +
> +      buf = []
> +      inflater = Zlib::Inflate.new(-Zlib::MAX_WBITS)
> +      FakeDisconnect = Class.new(RuntimeError)
> +      assert_raises(FakeDisconnect, "not Zlib::DataError not raised") do
> +        body.each do |part|
> +          buf << inflater.inflate(part)
> +          raise FakeDisconnect
> +        end
> +      end
> +      assert_raises(Zlib::BufError) { inflater.finish }
> +      buf.must_equal(%w(foo))
> +    end
> +  end
> +
>    # TODO: This is really just a special case of the above...
>    it 'be able to deflate String bodies' do
>      verify(200, 'Hello world!', 'deflate') do |status, headers, body|
> -- 
> EW
> 
> -- 
> 
> --- 
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-- 
Aaron Patterson
http://tenderlovemaking.com/

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