1 files changed, 62 insertions, 0 deletions
diff --git a/third_party/rust/h2/src/frame/window_update.rs b/third_party/rust/h2/src/frame/window_update.rs
new file mode 100644
index 0000000000..eed2ce17ec
--- /dev/null
+++ b/third_party/rust/h2/src/frame/window_update.rs
@@ -0,0 +1,62 @@
+use crate::frame::{self, Error, Head, Kind, StreamId};
+
+use bytes::BufMut;
+
+const SIZE_INCREMENT_MASK: u32 = 1 << 31;
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub struct WindowUpdate {
+    stream_id: StreamId,
+    size_increment: u32,
+}
+
+impl WindowUpdate {
+    pub fn new(stream_id: StreamId, size_increment: u32) -> WindowUpdate {
+        WindowUpdate {
+            stream_id,
+            size_increment,
+        }
+    }
+
+    pub fn stream_id(&self) -> StreamId {
+        self.stream_id
+    }
+
+    pub fn size_increment(&self) -> u32 {
+        self.size_increment
+    }
+
+    /// Builds a `WindowUpdate` frame from a raw frame.
+    pub fn load(head: Head, payload: &[u8]) -> Result<WindowUpdate, Error> {
+        debug_assert_eq!(head.kind(), crate::frame::Kind::WindowUpdate);
+        if payload.len() != 4 {
+            return Err(Error::BadFrameSize);
+        }
+
+        // Clear the most significant bit, as that is reserved and MUST be ignored
+        // when received.
+        let size_increment = unpack_octets_4!(payload, 0, u32) & !SIZE_INCREMENT_MASK;
+
+        if size_increment == 0 {
+            return Err(Error::InvalidWindowUpdateValue);
+        }
+
+        Ok(WindowUpdate {
+            stream_id: head.stream_id(),
+            size_increment,
+        })
+    }
+
+    pub fn encode<B: BufMut>(&self, dst: &mut B) {
+        tracing::trace!("encoding WINDOW_UPDATE; id={:?}", self.stream_id);
+        let head = Head::new(Kind::WindowUpdate, 0, self.stream_id);
+        head.encode(4, dst);
+        dst.put_u32(self.size_increment);
+    }
+}
+
+impl<B> From<WindowUpdate> for frame::Frame<B> {
+    fn from(src: WindowUpdate) -> Self {
+        frame::Frame::WindowUpdate(src)
+    }
+}