feat(client,server): remove tcp feature and code (#2929)

This removes the `tcp` feature from hyper's `Cargo.toml`, and the code it enabled:

- `HttpConnector`
- `GaiResolver`
- `AddrStream`

And parts of `Client` and `Server` that used those types. Alternatives will be available in the `hyper-util` crate.

Closes #2856 
Co-authored-by: MrGunflame <mrgunflame@protonmail.com>

src/client/connect/dns.rs

@@ -22,18 +22,9 @@
 //! });
 //! ```
 use std::error::Error;
-use std::future::Future;
-use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs};
-use std::pin::Pin;
+use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr};
 use std::str::FromStr;
-use std::task::{self, Poll};
-use std::{fmt, io, vec};
-
-use tokio::task::JoinHandle;
-use tower_service::Service;
-use tracing::debug;
-
-pub(super) use self::sealed::Resolve;
+use std::{fmt, vec};
 
 /// A domain name to resolve into IP addresses.
 #[derive(Clone, Hash, Eq, PartialEq)]
@@ -52,11 +43,6 @@ pub struct GaiAddrs {
     inner: SocketAddrs,
 }
 
-/// A future to resolve a name returned by `GaiResolver`.
-pub struct GaiFuture {
-    inner: JoinHandle<Result<SocketAddrs, io::Error>>,
-}
-
 impl Name {
     pub(super) fn new(host: Box<str>) -> Name {
         Name { host }
@@ -108,63 +94,12 @@ impl GaiResolver {
     }
 }
 
-impl Service<Name> for GaiResolver {
-    type Response = GaiAddrs;
-    type Error = io::Error;
-    type Future = GaiFuture;
-
-    fn poll_ready(&mut self, _cx: &mut task::Context<'_>) -> Poll<Result<(), io::Error>> {
-        Poll::Ready(Ok(()))
-    }
-
-    fn call(&mut self, name: Name) -> Self::Future {
-        let blocking = tokio::task::spawn_blocking(move || {
-            debug!("resolving host={:?}", name.host);
-            (&*name.host, 0)
-                .to_socket_addrs()
-                .map(|i| SocketAddrs { iter: i })
-        });
-
-        GaiFuture { inner: blocking }
-    }
-}
-
 impl fmt::Debug for GaiResolver {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.pad("GaiResolver")
     }
 }
 
-impl Future for GaiFuture {
-    type Output = Result<GaiAddrs, io::Error>;
-
-    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
-        Pin::new(&mut self.inner).poll(cx).map(|res| match res {
-            Ok(Ok(addrs)) => Ok(GaiAddrs { inner: addrs }),
-            Ok(Err(err)) => Err(err),
-            Err(join_err) => {
-                if join_err.is_cancelled() {
-                    Err(io::Error::new(io::ErrorKind::Interrupted, join_err))
-                } else {
-                    panic!("gai background task failed: {:?}", join_err)
-                }
-            }
-        })
-    }
-}
-
-impl fmt::Debug for GaiFuture {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("GaiFuture")
-    }
-}
-
-impl Drop for GaiFuture {
-    fn drop(&mut self) {
-        self.inner.abort();
-    }
-}
-
 impl Iterator for GaiAddrs {
     type Item = SocketAddr;
 
@@ -190,22 +125,6 @@ impl SocketAddrs {
         }
     }
 
-    pub(super) fn try_parse(host: &str, port: u16) -> Option<SocketAddrs> {
-        if let Ok(addr) = host.parse::<Ipv4Addr>() {
-            let addr = SocketAddrV4::new(addr, port);
-            return Some(SocketAddrs {
-                iter: vec![SocketAddr::V4(addr)].into_iter(),
-            });
-        }
-        if let Ok(addr) = host.parse::<Ipv6Addr>() {
-            let addr = SocketAddrV6::new(addr, port, 0, 0);
-            return Some(SocketAddrs {
-                iter: vec![SocketAddr::V6(addr)].into_iter(),
-            });
-        }
-        None
-    }
-
     #[inline]
     fn filter(self, predicate: impl FnMut(&SocketAddr) -> bool) -> SocketAddrs {
         SocketAddrs::new(self.iter.filter(predicate).collect())
@@ -239,10 +158,6 @@ impl SocketAddrs {
     pub(super) fn is_empty(&self) -> bool {
         self.iter.as_slice().is_empty()
     }
-
-    pub(super) fn len(&self) -> usize {
-        self.iter.as_slice().len()
-    }
 }
 
 impl Iterator for SocketAddrs {
@@ -318,12 +233,12 @@ impl Future for TokioThreadpoolGaiFuture {
 */
 
 mod sealed {
-    use super::{SocketAddr, Name};
+    use super::{Name, SocketAddr};
     use crate::common::{task, Future, Poll};
     use tower_service::Service;
 
     // "Trait alias" for `Service<Name, Response = Addrs>`
-    pub trait Resolve {
+    pub(crate) trait Resolve {
         type Addrs: Iterator<Item = SocketAddr>;
         type Error: Into<Box<dyn std::error::Error + Send + Sync>>;
         type Future: Future<Output = Result<Self::Addrs, Self::Error>>;
@@ -352,14 +267,6 @@ mod sealed {
     }
 }
 
-pub(super) async fn resolve<R>(resolver: &mut R, name: Name) -> Result<R::Addrs, R::Error>
-where
-    R: Resolve,
-{
-    futures_util::future::poll_fn(|cx| resolver.poll_ready(cx)).await?;
-    resolver.resolve(name).await
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;