hyper_util/server/conn/auto/
upgrade.rs

1//! Upgrade utilities.
2
3use bytes::{Bytes, BytesMut};
4use hyper::{
5    rt::{Read, Write},
6    upgrade::Upgraded,
7};
8
9use crate::common::rewind::Rewind;
10
11/// Tries to downcast the internal trait object to the type passed.
12///
13/// On success, returns the downcasted parts. On error, returns the Upgraded back.
14/// This is a kludge to work around the fact that the machinery provided by
15/// [`hyper_util::server::conn::auto`] wraps the inner `T` with a private type
16/// that is not reachable from outside the crate.
17///
18/// [`hyper_util::server::conn::auto`]: crate::server::conn::auto
19///
20/// This kludge will be removed when this machinery is added back to the main
21/// `hyper` code.
22pub fn downcast<T>(upgraded: Upgraded) -> Result<Parts<T>, Upgraded>
23where
24    T: Read + Write + Unpin + 'static,
25{
26    let hyper::upgrade::Parts {
27        io: rewind,
28        mut read_buf,
29        ..
30    } = upgraded.downcast::<Rewind<T>>()?;
31
32    if let Some(pre) = rewind.pre {
33        read_buf = if read_buf.is_empty() {
34            pre
35        } else {
36            let mut buf = BytesMut::from(read_buf);
37
38            buf.extend_from_slice(&pre);
39
40            buf.freeze()
41        };
42    }
43
44    Ok(Parts {
45        io: rewind.inner,
46        read_buf,
47    })
48}
49
50/// The deconstructed parts of an [`Upgraded`] type.
51///
52/// Includes the original IO type, and a read buffer of bytes that the
53/// HTTP state machine may have already read before completing an upgrade.
54#[derive(Debug)]
55#[non_exhaustive]
56pub struct Parts<T> {
57    /// The original IO object used before the upgrade.
58    pub io: T,
59    /// A buffer of bytes that have been read but not processed as HTTP.
60    ///
61    /// For instance, if the `Connection` is used for an HTTP upgrade request,
62    /// it is possible the server sent back the first bytes of the new protocol
63    /// along with the response upgrade.
64    ///
65    /// You will want to check for any existing bytes if you plan to continue
66    /// communicating on the IO object.
67    pub read_buf: Bytes,
68}
hyper_util/server/conn/auto/upgrade.rs

hyper_util/server/conn/auto/
upgrade.rs
