Add GoAway support

src/frame/go_away.rs

@@ -1,4 +1,7 @@
-use frame::{Error, StreamId};
+use error::Reason;
+use frame::{self, Head, Error, Kind, StreamId};
+
+use bytes::{BufMut, BigEndian};
 
 #[derive(Debug)]
 pub struct GoAway {
@@ -7,6 +10,10 @@ pub struct GoAway {
 }
 
 impl GoAway {
+    pub fn reason(&self) -> Reason {
+        self.error_code.into()
+    }
+
     pub fn load(payload: &[u8]) -> Result<GoAway, Error> {
         if payload.len() < 8 {
             // Invalid payload len
@@ -22,4 +29,18 @@ impl GoAway {
             error_code: error_code,
         })
     }
+
+    pub fn encode<B: BufMut>(&self, dst: &mut B) {
+        trace!("encoding GO_AWAY; code={}", self.error_code);
+        let head = Head::new(Kind::GoAway, 0, StreamId::zero());
+        head.encode(8, dst);
+        dst.put_u32::<BigEndian>(self.last_stream_id.into());
+        dst.put_u32::<BigEndian>(self.error_code);
+    }
+}
+
+impl<B> From<GoAway> for frame::Frame<B> {
+    fn from(src: GoAway) -> Self {
+        frame::Frame::GoAway(src)
+    }
 }