extract Frame creation into FrameFactory

1 files changed, 64 insertions, 0 deletions

diff --git a/lib/plum/frame_utils.rb b/lib/plum/frame_utils.rb
new file mode 100644
index 0000000..2694f5a
--- /dev/null
+++ b/lib/plum/frame_utils.rb
@@ -0,0 +1,64 @@
+using Plum::BinaryString
+
+module Plum
+  module FrameUtils
+    # Splits the frame into multiple frames if the payload size exceeds max size.
+    #
+    # @param max [Integer] The maximum size of a frame payload.
+    # @return [Array<Frame>] The splitted frames.
+    def split_data(max)
+      return [self] if self.length <= max
+      raise "Frame type must be DATA" unless self.type == :data
+
+      fragments = []
+      pos = 0
+      while pos <= self.length # data may be empty
+        fragments << self.payload.byteslice(pos, max)
+        pos += max
+      end
+
+      frames = []
+      last = Frame.data(stream_id, fragments.pop, *(self.flags & [:end_stream]))
+      fragments.each do |fragment|
+        frames << Frame.data(stream_id, fragment, *(self.flags - [:end_stream]))
+      end
+      frames << last
+      frames
+    end
+
+    def split_headers(max)
+      return [self] if self.length <= max
+      raise "Frame type must be DATA" unless [:headers, :push_promise].include?(self.type)
+
+      fragments = []
+      pos = 0
+      while pos < self.length
+        fragments << self.payload.byteslice(pos, max)
+        pos += max
+      end
+
+      frames = []
+      frames << Frame.new(type_value: self.type_value, flags: self.flags - [:end_headers], stream_id: self.stream_id, payload: fragments.shift)
+      if fragments.size > 0
+        last = Frame.continuation(stream_id, fragments.pop, *(self.flags & [:end_headers]))
+        fragments.each do |fragment|
+          frames << Frame.continuation(stream_id, fragment)
+        end
+        frames << last
+      end
+      frames
+    end
+
+    # Parses SETTINGS frame payload. Ignores unknown settings type (see RFC7540 6.5.2).
+    #
+    # @return [Hash<Symbol, Integer>] The parsed strings.
+    def parse_settings
+      (self.length / 6).times.map {|i|
+        id = self.payload.uint16(6 * i)
+        val = self.payload.uint32(6 * i + 2)
+        name = Frame::SETTINGS_TYPE.key(id) or next nil
+        [name, val]
+      }.compact.to_h
+    end
+  end
+end