blob: 039936fc7145a37b47396a372f03af2a3ad86bb7 [file] [log] [blame]
use byteorder::{BigEndian, ByteOrder};
use std::u32;
/// A stream identifier, as described in [Section 5.1.1] of RFC 7540.
///
/// Streams are identified with an unsigned 31-bit integer. Streams
/// initiated by a client MUST use odd-numbered stream identifiers; those
/// initiated by the server MUST use even-numbered stream identifiers. A
/// stream identifier of zero (0x0) is used for connection control
/// messages; the stream identifier of zero cannot be used to establish a
/// new stream.
///
/// [Section 5.1.1]: https://tools.ietf.org/html/rfc7540#section-5.1.1
#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct StreamId(u32);
#[derive(Debug, Copy, Clone)]
pub struct StreamIdOverflow;
const STREAM_ID_MASK: u32 = 1 << 31;
impl StreamId {
/// Stream ID 0.
pub const ZERO: StreamId = StreamId(0);
/// The maximum allowed stream ID.
pub const MAX: StreamId = StreamId(u32::MAX >> 1);
/// Parse the stream ID
#[inline]
pub fn parse(buf: &[u8]) -> (StreamId, bool) {
let unpacked = BigEndian::read_u32(buf);
let flag = unpacked & STREAM_ID_MASK == STREAM_ID_MASK;
// Now clear the most significant bit, as that is reserved and MUST be
// ignored when received.
(StreamId(unpacked & !STREAM_ID_MASK), flag)
}
/// Returns true if this stream ID corresponds to a stream that
/// was initiated by the client.
pub fn is_client_initiated(&self) -> bool {
let id = self.0;
id != 0 && id % 2 == 1
}
/// Returns true if this stream ID corresponds to a stream that
/// was initiated by the server.
pub fn is_server_initiated(&self) -> bool {
let id = self.0;
id != 0 && id % 2 == 0
}
/// Return a new `StreamId` for stream 0.
#[inline]
pub fn zero() -> StreamId {
StreamId::ZERO
}
/// Returns true if this stream ID is zero.
pub fn is_zero(&self) -> bool {
self.0 == 0
}
/// Returns the next stream ID initiated by the same peer as this stream
/// ID, or an error if incrementing this stream ID would overflow the
/// maximum.
pub fn next_id(&self) -> Result<StreamId, StreamIdOverflow> {
let next = self.0 + 2;
if next > StreamId::MAX.0 {
Err(StreamIdOverflow)
} else {
Ok(StreamId(next))
}
}
}
impl From<u32> for StreamId {
fn from(src: u32) -> Self {
assert_eq!(src & STREAM_ID_MASK, 0, "invalid stream ID -- MSB is set");
StreamId(src)
}
}
impl From<StreamId> for u32 {
fn from(src: StreamId) -> Self {
src.0
}
}
impl PartialEq<u32> for StreamId {
fn eq(&self, other: &u32) -> bool {
self.0 == *other
}
}