Merge pull request #87 from badeend/reuseaddr

Document SO_REUSEADDR to be the default for TCP `bind`
WebAssembly · Jan 3, 2024 · 7b7b7da · 7b7b7da
2 parents 333b8a8 + 6907592
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diff --git a/Posix-compatibility.md b/Posix-compatibility.md
@@ -156,6 +156,7 @@ Legend:
 | ✅ | TCP_KEEPIDLE <br/><sub>TCP_KEEPALIVE on MacOS</sub> | [`tcp-socket::(set-)keep-alive-idle-time`][tcp]                               | linux, windows, macos, freebsd, jvm, .net, libuv, go, nginx, curl |
 | ✅ | TCP_KEEPINTVL                   | [`tcp-socket::(set-)keep-alive-interval`][tcp]                                                    | linux, windows, macos, freebsd, jvm, .net, libuv, go, nginx, curl |
 | ✅ | TCP_KEEPCNT                     | [`tcp-socket::(set-)keep-alive-count`][tcp]                                                       | linux, windows, macos, freebsd, jvm, .net, libuv, nginx |
+| ✅ | SO_REUSEADDR for TCP            | Enabled by default. See [`tcp-socket::bind`][tcp]                              | posix, linux, windows, macos, freebsd, jvm, .net, libuv, go, openssl, nginx, curl, exim |
 | ⛔ | SO_ERROR                        | Not necessary. WIT has (or will have) native support for asynchronous results. | posix, linux, windows, macos, freebsd, jvm, .net, rust, libuv, go, openssl, nginx, curl, msquic |
 | ⛔ | SO_TYPE                         | Can be inferred from the socket resource type.                                 | posix, linux, windows, macos, freebsd, jvm, .net, go, openssl, nginx, curl, exim |
 | ⛔ | SO_PROTOCOL <br/><sub>SO_PROTOCOL_INFO on Windows</sub> | Can be inferred from the socket resource type.         | linux, windows, freebsd, .net, exim |
@@ -182,7 +183,7 @@ Legend:
 | ❔ | IPV6_MTU_DISCOVER               | [#79][79]                                | linux, windows, openssl, nginx, curl, msquic |
 | ❔ | TCP_NODELAY                     | [#75][75]                                | posix, linux, windows, macos, freebsd, jvm, .net, rust, libuv, go, openssl, nginx, curl, exim |
 | ❔ | TCP_CORK <br/><sub>TCP_NOPUSH on MacOS & FreeBSD</sub> | [#75][75]         | linux, macos, freebsd, nginx, exim |
-| ❔ | SO_REUSEADDR                    | [#74][74]                                | posix, linux, windows, macos, freebsd, jvm, .net, libuv, go, openssl, nginx, curl, exim |
+| ❔ | SO_REUSEADDR for UDP            | [#74][74]                                | posix, linux, windows, macos, freebsd, jvm, .net, libuv, go, openssl, nginx, curl, exim |
 | ❔ | SO_EXCLUSIVEADDRUSE             | [#74][74]                                | windows |
 | ❔ | SO_RANDOMIZE_PORT               | [#74][74]                                | windows |
 | ❔ | SO_RANDOMPORT                   | [#74][74]                                | macos |

diff --git a/imports.md b/imports.md
@@ -1190,6 +1190,11 @@ implicitly bind the socket.</p>
 <li><code>not-in-progress</code>:           A <code>bind</code> operation is not in progress.</li>
 <li><code>would-block</code>:               Can't finish the operation, it is still in progress. (EWOULDBLOCK, EAGAIN)</li>
 </ul>
+<h1>Implementors note</h1>
+<p>When binding to a non-zero port, this bind operation shouldn't be affected by the TIME_WAIT
+state of a recently closed socket on the same local address. In practice this means that the SO_REUSEADDR
+socket option should be set implicitly on all platforms, except on Windows where this is the default behavior
+and SO_REUSEADDR performs something different entirely.</p>
 <h1>References</h1>
 <ul>
 <li><a href="https://pubs.opengroup.org/onlinepubs/9699919799/functions/bind.html">https://pubs.opengroup.org/onlinepubs/9699919799/functions/bind.html</a></li>

diff --git a/wit/tcp.wit b/wit/tcp.wit
@@ -42,6 +42,12 @@ interface tcp {
         /// - `address-not-bindable`:      `local-address` is not an address that the `network` can bind to. (EADDRNOTAVAIL)
         /// - `not-in-progress`:           A `bind` operation is not in progress.
         /// - `would-block`:               Can't finish the operation, it is still in progress. (EWOULDBLOCK, EAGAIN)
+        /// 
+        /// # Implementors note
+        /// When binding to a non-zero port, this bind operation shouldn't be affected by the TIME_WAIT
+        /// state of a recently closed socket on the same local address. In practice this means that the SO_REUSEADDR 
+        /// socket option should be set implicitly on all platforms, except on Windows where this is the default behavior
+        /// and SO_REUSEADDR performs something different entirely.
         ///
         /// # References
         /// - <https://pubs.opengroup.org/onlinepubs/9699919799/functions/bind.html>