Work

src/frame/head.rs

@@ -1,5 +1,7 @@
 use super::Error;
 
+use bytes::{BufMut, BigEndian};
+
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub struct Head {
     kind: Kind,
@@ -25,9 +27,19 @@ pub enum Kind {
 
 pub type StreamId = u32;
 
+const STREAM_ID_MASK: StreamId = 0x80000000;
+
 // ===== impl Head =====
 
 impl Head {
+    pub fn new(kind: Kind, flag: u8, stream_id: StreamId) -> Head {
+        Head {
+            kind: kind,
+            flag: flag,
+            stream_id: stream_id,
+        }
+    }
+
     /// Parse an HTTP/2.0 frame header
     pub fn parse(header: &[u8]) -> Head {
         Head {
@@ -48,6 +60,21 @@ impl Head {
     pub fn flag(&self) -> u8 {
         self.flag
     }
+
+    pub fn encode_len(&self) -> usize {
+        super::FRAME_HEADER_LEN
+    }
+
+    pub fn encode<T: BufMut>(&self, payload_len: usize, dst: &mut T) -> Result<(), Error> {
+        debug_assert_eq!(self.encode_len(), dst.remaining_mut());
+        debug_assert!(self.stream_id & STREAM_ID_MASK == 0);
+
+        dst.put_uint::<BigEndian>(payload_len as u64, 3);
+        dst.put_u8(self.kind as u8);
+        dst.put_u8(self.flag);
+        dst.put_u32::<BigEndian>(self.stream_id);
+        Ok(())
+    }
 }
 
 /// Parse the next 4 octets in the given buffer, assuming they represent an
@@ -58,7 +85,7 @@ impl Head {
 fn parse_stream_id(buf: &[u8]) -> StreamId {
     let unpacked = unpack_octets_4!(buf, 0, u32);
     // Now clear the most significant bit, as that is reserved and MUST be ignored when received.
-    unpacked & !0x80000000
+    unpacked & !STREAM_ID_MASK
 }
 
 // ===== impl Kind =====