97 lines
2.7 KiB
Rust
97 lines
2.7 KiB
Rust
use std::u32;
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/// A stream identifier, as described in [Section 5.1.1] of RFC 7540.
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///
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/// Streams are identified with an unsigned 31-bit integer. Streams
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/// initiated by a client MUST use odd-numbered stream identifiers; those
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/// initiated by the server MUST use even-numbered stream identifiers. A
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/// stream identifier of zero (0x0) is used for connection control
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/// messages; the stream identifier of zero cannot be used to establish a
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/// new stream.
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///
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/// [Section 5.1.1]: https://tools.ietf.org/html/rfc7540#section-5.1.1
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#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
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pub struct StreamId(u32);
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#[derive(Debug, Copy, Clone)]
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pub struct StreamIdOverflow;
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const STREAM_ID_MASK: u32 = 1 << 31;
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impl StreamId {
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/// Stream ID 0.
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pub const ZERO: StreamId = StreamId(0);
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/// The maximum allowed stream ID.
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pub const MAX: StreamId = StreamId(u32::MAX >> 1);
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/// Parse the stream ID
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#[inline]
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pub fn parse(buf: &[u8]) -> (StreamId, bool) {
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let mut ubuf = [0; 4];
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ubuf.copy_from_slice(&buf[0..4]);
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let unpacked = u32::from_be_bytes(ubuf);
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let flag = unpacked & STREAM_ID_MASK == STREAM_ID_MASK;
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// Now clear the most significant bit, as that is reserved and MUST be
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// ignored when received.
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(StreamId(unpacked & !STREAM_ID_MASK), flag)
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}
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/// Returns true if this stream ID corresponds to a stream that
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/// was initiated by the client.
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pub fn is_client_initiated(&self) -> bool {
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let id = self.0;
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id != 0 && id % 2 == 1
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}
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/// Returns true if this stream ID corresponds to a stream that
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/// was initiated by the server.
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pub fn is_server_initiated(&self) -> bool {
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let id = self.0;
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id != 0 && id % 2 == 0
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}
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/// Return a new `StreamId` for stream 0.
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#[inline]
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pub fn zero() -> StreamId {
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StreamId::ZERO
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}
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/// Returns true if this stream ID is zero.
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pub fn is_zero(&self) -> bool {
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self.0 == 0
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}
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/// Returns the next stream ID initiated by the same peer as this stream
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/// ID, or an error if incrementing this stream ID would overflow the
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/// maximum.
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pub fn next_id(&self) -> Result<StreamId, StreamIdOverflow> {
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let next = self.0 + 2;
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if next > StreamId::MAX.0 {
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Err(StreamIdOverflow)
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} else {
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Ok(StreamId(next))
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}
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}
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}
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impl From<u32> for StreamId {
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fn from(src: u32) -> Self {
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assert_eq!(src & STREAM_ID_MASK, 0, "invalid stream ID -- MSB is set");
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StreamId(src)
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}
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}
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impl From<StreamId> for u32 {
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fn from(src: StreamId) -> Self {
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src.0
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}
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}
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impl PartialEq<u32> for StreamId {
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fn eq(&self, other: &u32) -> bool {
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self.0 == *other
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}
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}
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