enable Range: responses for static files for most models

The FileStreamer class of EventMachine (and by extension
NeverBlock) unfortunately doesn't handle this.  It's possible
to do with Revactor (since it uses Rev under the covers),
but we'll support what we can easily for now.

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/rainbows/response/range.rb b/lib/rainbows/response/range.rb
new file mode 100644
index 0000000..4c0d4a1
--- /dev/null
+++ b/lib/rainbows/response/range.rb
@@ -0,0 +1,34 @@
+# -*- encoding: binary -*-
+# :enddoc:
+module Rainbows::Response::Range
+  HTTP_RANGE = 'HTTP_RANGE'
+  Content_Range = 'Content-Range'.freeze
+  Content_Length = 'Content-Length'.freeze
+
+  # This does not support multipart responses (does anybody actually
+  # use those?) +headers+ is always a Rack::Utils::HeaderHash
+  def parse_range(env, status, headers)
+    if 200 == status.to_i &&
+        (clen = headers[Content_Length]) &&
+        /\Abytes=(\d+-\d*|\d*-\d+)\z/ =~ env[HTTP_RANGE]
+      a, b = $1.split(/-/)
+      clen = clen.to_i
+      if b.nil? # bytes=M-
+        offset = a.to_i
+        count = clen - offset
+      elsif a.empty? # bytes=-N
+        offset = clen - b.to_i
+        count = clen - offset
+      else  # bytes=M-N
+        offset = a.to_i
+        count = b.to_i + 1 - offset
+      end
+      raise Rainbows::Response416 if count <= 0 || offset >= clen
+      count = clen if count > clen
+      headers[Content_Length] = count.to_s
+      headers[Content_Range] = "bytes #{offset}-#{offset+count-1}/#{clen}"
+      [ status, offset, count ]
+    end
+    # nil if no status
+  end
+end