ntex_h2/frame/
stream_id.rs

1/// A stream identifier, as described in [Section 5.1.1] of RFC 7540.
2///
3/// Streams are identified with an unsigned 31-bit integer. Streams
4/// initiated by a client MUST use odd-numbered stream identifiers; those
5/// initiated by the server MUST use even-numbered stream identifiers.  A
6/// stream identifier of zero (0x0) is used for connection control
7/// messages; the stream identifier of zero cannot be used to establish a
8/// new stream.
9///
10/// [Section 5.1.1]: https://tools.ietf.org/html/rfc7540#section-5.1.1
11#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
12pub struct StreamId(u32);
13
14#[derive(Debug, Copy, Clone)]
15pub struct StreamIdOverflow;
16
17const STREAM_ID_MASK: u32 = 1 << 31;
18
19impl StreamId {
20    /// Stream ID 0.
21    pub const CON: StreamId = StreamId(0);
22
23    /// Stream ID 1.
24    pub const CLIENT: StreamId = StreamId(1);
25
26    /// The maximum allowed stream ID.
27    pub const MAX: StreamId = StreamId(u32::MAX >> 1);
28
29    /// Parse the stream ID
30    #[inline]
31    pub fn parse(buf: &[u8]) -> (StreamId, bool) {
32        let mut ubuf = [0; 4];
33        ubuf.copy_from_slice(&buf[0..4]);
34        let unpacked = u32::from_be_bytes(ubuf);
35        let flag = unpacked & STREAM_ID_MASK == STREAM_ID_MASK;
36
37        // Now clear the most significant bit, as that is reserved and MUST be
38        // ignored when received.
39        (StreamId(unpacked & !STREAM_ID_MASK), flag)
40    }
41
42    /// Returns true if this stream ID corresponds to a stream that
43    /// was initiated by the client.
44    pub const fn is_client_initiated(&self) -> bool {
45        let id = self.0;
46        id != 0 && id % 2 == 1
47    }
48
49    /// Returns true if this stream ID corresponds to a stream that
50    /// was initiated by the server.
51    pub const fn is_server_initiated(&self) -> bool {
52        let id = self.0;
53        id != 0 && id % 2 == 0
54    }
55
56    /// Return a new `StreamId` for stream 0.
57    #[inline]
58    pub const fn zero() -> StreamId {
59        StreamId::CON
60    }
61
62    /// Returns true if this stream ID is zero.
63    pub const fn is_zero(&self) -> bool {
64        self.0 == 0
65    }
66
67    /// Returns the next stream ID initiated by the same peer as this stream
68    /// ID, or an error if incrementing this stream ID would overflow the
69    /// maximum.
70    pub const fn next_id(&self) -> Result<StreamId, StreamIdOverflow> {
71        let next = self.0 + 2;
72        if next > StreamId::MAX.0 {
73            Err(StreamIdOverflow)
74        } else {
75            Ok(StreamId(next))
76        }
77    }
78}
79
80impl From<u32> for StreamId {
81    fn from(src: u32) -> Self {
82        assert_eq!(src & STREAM_ID_MASK, 0, "invalid stream ID -- MSB is set");
83        StreamId(src)
84    }
85}
86
87impl From<StreamId> for u32 {
88    fn from(src: StreamId) -> Self {
89        src.0
90    }
91}
92
93impl PartialEq<u32> for StreamId {
94    fn eq(&self, other: &u32) -> bool {
95        self.0 == *other
96    }
97}
ntex_h2/frame/stream_id.rs

ntex_h2/frame/
stream_id.rs
