feat(websocket): remove deflate compression option

This option is the only reason we pull in a dependency on the shared `zlib` library. Unfortunately, we cannot use a pure Rust backend here because that one does not support configuring the window bits of the deflate algorithm which is used in the deflate websocket extension.

Using websockets in libp2p is already crazy inefficient because you end up with double encryption when using `/wss` (which is enforced by browsers if your website is served via https). A good encryption algorithm like noise or TLS produces an output that looks completely random. Any attempt in compressing this is pretty much wasted CPU power.

Thus, I think removing this configuration option does not really hurt and allows us to remove the dependency on the `zlib` shared library.

Pull-Request: #3949.

.github/workflows/ci.yml

@@ -31,9 +31,6 @@ jobs:
     env:
       CRATE: ${{ matrix.crate }}
     steps:
-      - name: Install zlib for `libp2p-websocket` # https://github.com/paritytech/soketto/issues/72
-        run: sudo apt-get install zlib1g-dev --yes
-
       - uses: actions/checkout@v3
 
       - uses: r7kamura/rust-problem-matchers@d58b70c4a13c4866d96436315da451d8106f8f08 #v1.3.0

interop-tests/Dockerfile

@@ -1,12 +1,6 @@
 # syntax=docker/dockerfile:1.5-labs
 FROM rust:1.67.0 as builder
 
-# Install zlib as long as libp2p-websocket requires it: https://github.com/paritytech/soketto/issues/72
-RUN apt-get update && \
-    apt-get download zlib1g && \
-    mkdir /dpkg && \
-    for deb in *.deb; do dpkg --extract $deb /dpkg || exit 10; done
-
 # Run with access to the target cache to speed up builds
 WORKDIR /workspace
 ADD . .
@@ -19,6 +13,5 @@ RUN --mount=type=cache,target=./target \
 
 FROM gcr.io/distroless/cc
 COPY --from=builder /usr/local/bin/testplan /usr/local/bin/testplan
-COPY --from=builder /dpkg /
 ENV RUST_BACKTRACE=1
 ENTRYPOINT ["testplan"]

transports/websocket/CHANGELOG.md

@@ -3,7 +3,12 @@
 - Raise MSRV to 1.65.
   See [PR 3715].
 
+- Remove `WsConfig::use_deflate` option.
+  This allows us to remove the dependency on the `zlib` shared library.
+  See [PR 3949].
+
 [PR 3715]: https://github.com/libp2p/rust-libp2p/pull/3715
+[PR 3949]: https://github.com/libp2p/rust-libp2p/pull/3949
 
 ## 0.41.0
 

transports/websocket/Cargo.toml

@@ -20,7 +20,7 @@ log = "0.4.8"
 parking_lot = "0.12.0"
 quicksink = "0.1"
 rw-stream-sink = { workspace = true }
-soketto = { version = "0.7.0", features = ["deflate"] }
+soketto = "0.7.0"
 url = "2.1"
 webpki-roots = "0.23"
 

transports/websocket/src/framed.rs

@@ -32,7 +32,6 @@ use log::{debug, trace};
 use parking_lot::Mutex;
 use soketto::{
     connection::{self, CloseReason},
-    extension::deflate::Deflate,
     handshake,
 };
 use std::{collections::HashMap, ops::DerefMut, sync::Arc};
@@ -51,7 +50,6 @@ pub struct WsConfig<T> {
     max_data_size: usize,
     tls_config: tls::Config,
     max_redirects: u8,
-    use_deflate: bool,
     /// Websocket protocol of the inner listener.
     ///
     /// This is the suffix of the address provided in `listen_on`.
@@ -67,7 +65,6 @@ impl<T> WsConfig<T> {
             max_data_size: MAX_DATA_SIZE,
             tls_config: tls::Config::client(),
             max_redirects: 0,
-            use_deflate: false,
             listener_protos: HashMap::new(),
         }
     }
@@ -99,12 +96,6 @@ impl<T> WsConfig<T> {
         self.tls_config = c;
         self
     }
-
-    /// Should the deflate extension (RFC 7692) be used if supported?
-    pub fn use_deflate(&mut self, flag: bool) -> &mut Self {
-        self.use_deflate = flag;
-        self
-    }
 }
 
 type TlsOrPlain<T> = future::Either<future::Either<client::TlsStream<T>, server::TlsStream<T>>, T>;
@@ -285,19 +276,12 @@ where
 
         let transport = self.transport.clone();
         let tls_config = self.tls_config.clone();
-        let use_deflate = self.use_deflate;
         let max_redirects = self.max_redirects;
 
         let future = async move {
             loop {
-                match Self::dial_once(
-                    transport.clone(),
-                    addr,
-                    tls_config.clone(),
-                    use_deflate,
-                    role_override,
-                )
-                .await
+                match Self::dial_once(transport.clone(), addr, tls_config.clone(), role_override)
+                    .await
                 {
                     Ok(Either::Left(redirect)) => {
                         if remaining_redirects == 0 {
@@ -321,7 +305,6 @@ where
         transport: Arc<Mutex<T>>,
         addr: WsAddress,
         tls_config: tls::Config,
-        use_deflate: bool,
         role_override: Endpoint,
     ) -> Result<Either<String, Connection<T::Output>>, Error<T::Error>> {
         trace!("Dialing websocket address: {:?}", addr);
@@ -364,10 +347,6 @@ where
 
         let mut client = handshake::Client::new(stream, &addr.host_port, addr.path.as_ref());
 
-        if use_deflate {
-            client.add_extension(Box::new(Deflate::new(connection::Mode::Client)));
-        }
-
         match client
             .handshake()
             .map_err(|e| Error::Handshake(Box::new(e)))
@@ -403,7 +382,6 @@ where
         let remote_addr2 = remote_addr.clone(); // used for logging
         let tls_config = self.tls_config.clone();
         let max_size = self.max_data_size;
-        let use_deflate = self.use_deflate;
 
         async move {
             let stream = upgrade.map_err(Error::Transport).await?;
@@ -440,10 +418,6 @@ where
 
             let mut server = handshake::Server::new(stream);
 
-            if use_deflate {
-                server.add_extension(Box::new(Deflate::new(connection::Mode::Server)));
-            }
-
             let ws_key = {
                 let request = server
                     .receive_request()

transports/websocket/src/lib.rs

@@ -174,12 +174,6 @@ where
         self.transport.inner_mut().set_tls_config(c);
         self
     }
-
-    /// Should the deflate extension (RFC 7692) be used if supported?
-    pub fn use_deflate(&mut self, flag: bool) -> &mut Self {
-        self.transport.inner_mut().use_deflate(flag);
-        self
-    }
 }
 
 impl<T> Transport for WsConfig<T>