http2: fix parsing of goaway frames

There was a last stream id before the error code
As per section 6.8 of RFC 7540

Ticket: 7991
(cherry picked from commit 9a4a29e)

Author: catenacyber

rust/src/http2/http2.rs

@@ -69,7 +69,7 @@ pub enum HTTP2ConnectionState {
 
 const HTTP2_FRAME_HEADER_LEN: usize = 9;
 const HTTP2_MAGIC_LEN: usize = 24;
-const HTTP2_FRAME_GOAWAY_LEN: usize = 4;
+const HTTP2_FRAME_GOAWAY_LEN: usize = 8;
 const HTTP2_FRAME_RSTSTREAM_LEN: usize = 4;
 const HTTP2_FRAME_PRIORITY_LEN: usize = 5;
 const HTTP2_FRAME_WINDOWUPDATE_LEN: usize = 4;

rust/src/http2/parser.rs

@@ -161,6 +161,7 @@ pub struct HTTP2FrameGoAway {
 }
 
 pub fn http2_parse_frame_goaway(i: &[u8]) -> IResult<&[u8], HTTP2FrameGoAway> {
+    let (i, _last_stream_id) = be_u32(i)?;
     let (i, errorcode) = be_u32(i)?;
     Ok((i, HTTP2FrameGoAway { errorcode }))
 }