Set `SO_REUSEADDR` only non-Windows platforms (#3473)

* Fix: Per discussion in #2958, set `SO_REUSEADDR` only non-Windows platforms.

Add: Tests confirming that only a single webserver instance may
bind to a given address.

* Clean: Lint.

* Clean: another guess at making the formatter happy.

* Clean: More cargo fmt fun. (Running cargo fmt locally doesn't help.)

---------

Co-authored-by: Bryan A. Jones <bjones1@users.noreply.github.com>
Co-authored-by: Rob Ede <robjtede@icloud.com>

.github/workflows/ci-post-merge.yml

@@ -44,12 +44,12 @@ jobs:
           echo "RUSTFLAGS=-C target-feature=+crt-static" >> $GITHUB_ENV
 
       - name: Install Rust (${{ matrix.version.name }})
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: ${{ matrix.version.version }}
 
       - name: Install just, cargo-hack, cargo-nextest, cargo-ci-cache-clean
-        uses: taiki-e/install-action@v2.43.1
+        uses: taiki-e/install-action@v2.44.15
         with:
           tool: just,cargo-hack,cargo-nextest,cargo-ci-cache-clean
 
@@ -80,10 +80,10 @@ jobs:
         uses: rui314/setup-mold@v1
 
       - name: Install Rust
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
 
       - name: Install just, cargo-hack
-        uses: taiki-e/install-action@v2.43.1
+        uses: taiki-e/install-action@v2.44.15
         with:
           tool: just,cargo-hack
 

.github/workflows/ci.yml

@@ -59,12 +59,12 @@ jobs:
         uses: rui314/setup-mold@v1
 
       - name: Install Rust (${{ matrix.version.name }})
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: ${{ matrix.version.version }}
 
       - name: Install just, cargo-hack, cargo-nextest, cargo-ci-cache-clean
-        uses: taiki-e/install-action@v2.43.1
+        uses: taiki-e/install-action@v2.44.15
         with:
           tool: just,cargo-hack,cargo-nextest,cargo-ci-cache-clean
 
@@ -92,7 +92,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: nightly
 
@@ -108,12 +108,12 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust (nightly)
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: nightly
 
       - name: Install just
-        uses: taiki-e/install-action@v2.43.1
+        uses: taiki-e/install-action@v2.44.15
         with:
           tool: just
 

.github/workflows/coverage.yml

@@ -18,13 +18,13 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust (nightly)
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: nightly
           components: llvm-tools
 
       - name: Install just, cargo-llvm-cov, cargo-nextest
-        uses: taiki-e/install-action@v2.43.1
+        uses: taiki-e/install-action@v2.44.15
         with:
           tool: just,cargo-llvm-cov,cargo-nextest
 

.github/workflows/lint.yml

@@ -18,7 +18,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust (nightly)
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: nightly
           components: rustfmt
@@ -36,7 +36,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           components: clippy
 
@@ -55,7 +55,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust (nightly)
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: nightly
           components: rust-docs
@@ -66,17 +66,18 @@ jobs:
         run: cargo +nightly doc --no-deps --workspace --all-features
 
   check-external-types:
+    if: false # disable until https://github.com/awslabs/cargo-check-external-types/pull/177 is marged
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
 
       - name: Install Rust (nightly-2024-05-01)
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
           toolchain: nightly-2024-05-01
 
       - name: Install just
-        uses: taiki-e/install-action@v2.43.1
+        uses: taiki-e/install-action@v2.44.15
         with:
           tool: just
 
@@ -99,13 +100,13 @@ jobs:
       - name: Checkout PR branch
         uses: actions/checkout@v4
 
-      - name: Install Rust (nightly-2024-06-07)
-        uses: actions-rust-lang/setup-rust-toolchain@v1.9.0
+      - name: Install Rust (nightly-2024-09-30)
+        uses: actions-rust-lang/setup-rust-toolchain@v1.10.0
         with:
-          toolchain: nightly-2024-06-07
+          toolchain: nightly-2024-09-30
 
       - name: Install cargo-public-api
-        uses: taiki-e/install-action@v2.43.1
+        uses: taiki-e/install-action@v2.44.15
         with:
           tool: cargo-public-api
 

actix-web/CHANGES.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Minimum supported Rust version (MSRV) is now 1.75.
+- On Windows platforms, produce an error when invoking `HttpServer::bind` on a socket that's already in use. See [issue 2958](https://github.com/actix/actix-web/issues/2958).
 
 ## 4.9.0
 

actix-web/src/server.rs

@@ -1085,7 +1085,10 @@ fn create_tcp_listener(addr: net::SocketAddr, backlog: u32) -> io::Result<net::T
     use socket2::{Domain, Protocol, Socket, Type};
     let domain = Domain::for_address(addr);
     let socket = Socket::new(domain, Type::STREAM, Some(Protocol::TCP))?;
-    socket.set_reuse_address(true)?;
+    #[cfg(not(windows))]
+    {
+        socket.set_reuse_address(true)?;
+    }
     socket.bind(&addr.into())?;
     // clamp backlog to max u32 that fits in i32 range
     let backlog = cmp::min(backlog, i32::MAX as u32) as i32;

actix-web/tests/test_httpserver.rs

@@ -1,13 +1,10 @@
 #[cfg(feature = "openssl")]
 extern crate tls_openssl as openssl;
 
-#[cfg(any(unix, feature = "openssl"))]
-use {
-    actix_web::{web, App, HttpResponse, HttpServer},
-    std::{sync::mpsc, thread, time::Duration},
-};
+use std::{sync::mpsc, thread, time::Duration};
+
+use actix_web::{web, App, HttpResponse, HttpServer};
 
-#[cfg(unix)]
 #[actix_rt::test]
 async fn test_start() {
     let addr = actix_test::unused_addr();
@@ -53,6 +50,27 @@ async fn test_start() {
     let response = client.get(host.clone()).send().await.unwrap();
     assert!(response.status().is_success());
 
+    // Attempt to start a second server using the same address.
+    let result = HttpServer::new(|| {
+        App::new().service(
+            web::resource("/").route(web::to(|| async { HttpResponse::Ok().body("test") })),
+        )
+    })
+    .workers(1)
+    .backlog(1)
+    .max_connections(10)
+    .max_connection_rate(10)
+    .keep_alive(Duration::from_secs(10))
+    .client_request_timeout(Duration::from_secs(5))
+    .client_disconnect_timeout(Duration::ZERO)
+    .server_hostname("localhost")
+    .system_exit()
+    .disable_signals()
+    .bind(format!("{}", addr));
+
+    // This should fail: the address is in use.
+    assert!(result.is_err());
+
     srv.stop(false).await;
 }
 

justfile

@@ -10,6 +10,7 @@ fmt:
 # Downgrade dev-dependencies necessary to run MSRV checks/tests.
 [private]
 downgrade-for-msrv:
+    cargo update -p=parse-size --precise=1.0.0
     cargo update -p=clap --precise=4.4.18
 
 msrv := ```