# 0.3.12 (March 9, 2022)
* Avoid time operations that can panic (#599)
* Bump MSRV to Rust 1.49 (#606)
* Fix header decoding error when a header name is contained at a continuation
header boundary (#589)
* Remove I/O type names from handshake `tracing` spans (#608)
## Motivation
Currently, the `tracing` spans for the client and server handshakes
contain the name of the I/O type. In some cases, where nested I/O types
are in use, these names can be quite long; for example, in Linkerd, we
see log lines like this:
```
2022-03-07T23:38:15.322506670Z [ 10533.916262s] DEBUG ThreadId(01) inbound:accept{client.addr=192.168.1.9:1227}:server{port=4143}:direct:gateway{dst=server.echo.svc.cluster.local:8080}:server_handshake{io=hyper::common::io:⏪:Rewind<linkerd_io::either::EitherIo<linkerd_io::sensor::SensorIo<linkerd_io::prefixed::PrefixedIo<linkerd_io::either::EitherIo<tokio_rustls::server::TlsStream<linkerd_io::either::EitherIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>, linkerd_io::prefixed::PrefixedIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>>>>, linkerd_io::either::EitherIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>, linkerd_io::prefixed::PrefixedIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>>>>>, linkerd_transport_metrics::sensor::Sensor>, linkerd_io::sensor::SensorIo<linkerd_io::either::EitherIo<tokio_rustls::server::TlsStream<linkerd_io::either::EitherIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>, linkerd_io::prefixed::PrefixedIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>>>>, linkerd_io::either::EitherIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>, linkerd_io::prefixed::PrefixedIo<linkerd_io::scoped::ScopedIo<tokio::net::tcp::stream::TcpStream>>>>, linkerd_transport_metrics::sensor::Sensor>>>}:FramedWrite::buffer{frame=Settings { flags: (0x0), initial_window_size: 65535, max_frame_size: 16384 }}: h2::codec::framed_write: send frame=Settings { flags: (0x0), initial_window_size: 65535, max_frame_size: 16384 }
```
which is kinda not great.
## Solution
This branch removes the IO type's type name from the spans for the
server and client handshakes. In practice, these are not particularly
useful, because a given server or client instance is parameterized over
the IO types and will only serve connections of that type.
We have reports of runtime panics (linkerd/linkerd2#7748) that sound a
lot like rust-lang/rust#86470. We don't have any evidence that these
panics originate in h2, but there is one use of `Instant::sub` that
could panic in this way.
Even though this is almost definitely a bug in Rust, it seems most
prudent to actively avoid the uses of `Instant` that are prone to this
bug. These fixes should ultimately be made in the standard library, but
this change lets us avoid this problem while we wait for those fixes.
This change replaces uses of `Instant::elapsed` and `Instant::sub` with
calls to `Instant::saturating_duration_since` to prevent this class of
panic.
See also hyperium/hyper#2746
h2::Error now knows whether protocol errors happened because the user
sent them, because it was received from the remote peer, or because
the library itself emitted an error because it detected a protocol
violation.
It also keeps track of whether it came from a RST_STREAM or GO_AWAY
frame, and in the case of the latter, it includes the additional
debug data if any.
Fixes#530
This completely refactors how headers are hpack-encoded.
Instead of trying to be clever, constructing frames on the go
while hpack-encoding, we just make a blob of all the
hpack-encoded headers first, and then we split that blob
in as many frames as necessary.
If a user stored a `StreamRef` to the same stream in the request or
response extensions, they would be dropped while the internal store lock
was held. That would lead to a deadlock, since dropping a stream ref
will try to take the store lock to clean up.
Clear extensions of Request and Response before locking store, prevent
this.
Fixeshyperium/hyper#2621
I don't even understand why that should panic, what's wrong with values
greater than 0x0fff_ffff? If we truly wish to avoid very large dynamic
tables, we should do so when we get the large SETTINGS_HEADER_TABLE_SIZE
value, not when encoding it.
This allows to use `h2` on wasm platforms which lack an
`Instant::now` implementation by setting the number of streams to
0 with: `h2::client::Builder::max_concurrent_reset_streams`.
