Add function to downcast a stream error to a network-related error. Similar to the existing filesystem-error-code and http-error-code functions.

badeend · badeend · commit 7411bf12794a · 2024-09-14T13:35:35.000+02:00
diff --git a/crates/wasi-http/src/bindings.rs b/crates/wasi-http/src/bindings.rs
@@ -8,6 +8,7 @@ mod generated {
     wasmtime::component::bindgen!({
         path: "wit",
         world: "wasi:http/proxy",
+        features: ["network-error-code"],
         tracing: true,
         // Flag this as "possibly async" which will cause the exports to be
         // generated as async, but none of the imports here are async since
@@ -56,6 +57,7 @@ pub mod sync {
         #![allow(missing_docs)]
         wasmtime::component::bindgen!({
             world: "wasi:http/proxy",
+            features: ["network-error-code"],
             tracing: true,
             async: false,
             with: {
diff --git a/crates/wasi-http/wit/deps/sockets/network.wit b/crates/wasi-http/wit/deps/sockets/network.wit
@@ -1,5 +1,8 @@
 @since(version = 0.2.0)
 interface network {
+    @unstable(feature = network-error-code)
+    use wasi:io/error@0.2.1.{error};
+
     /// An opaque resource that represents access to (a subset of) the network.
     /// This enables context-based security for networking.
     /// There is no need for this to map 1:1 to a physical network interface.
@@ -105,6 +108,19 @@ interface network {
         permanent-resolver-failure,
     }
 
+    /// Attempts to extract a network-related `error-code` from the stream
+    /// `error` provided.
+    ///
+    /// Stream operations which return `stream-error::last-operation-failed`
+    /// have a payload with more information about the operation that failed.
+    /// This payload can be passed through to this function to see if there's
+    /// network-related information about the error to return.
+    ///
+    /// Note that this function is fallible because not all stream-related
+    /// errors are network-related errors.
+    @unstable(feature = network-error-code)
+    network-error-code: func(err: borrow<error>) -> option<error-code>;
+
     @since(version = 0.2.0)
     enum ip-address-family {
         /// Similar to `AF_INET` in POSIX.
diff --git a/crates/wasi/src/bindings.rs b/crates/wasi/src/bindings.rs
@@ -148,6 +148,7 @@ pub mod sync {
         wasmtime::component::bindgen!({
             path: "wit",
             world: "wasi:cli/command",
+            features: ["network-error-code"],
             tracing: true,
             trappable_error_type: {
                 "wasi:io/streams/stream-error" => StreamError,
@@ -326,6 +327,7 @@ mod async_io {
     wasmtime::component::bindgen!({
         path: "wit",
         world: "wasi:cli/command",
+        features: ["network-error-code"],
         tracing: true,
         trappable_imports: true,
         async: {
diff --git a/crates/wasi/src/host/network.rs b/crates/wasi/src/host/network.rs
@@ -15,6 +15,19 @@ where
     fn convert_error_code(&mut self, error: SocketError) -> anyhow::Result<ErrorCode> {
         error.downcast()
     }
+
+    fn network_error_code(
+        &mut self,
+        err: Resource<anyhow::Error>,
+    ) -> anyhow::Result<Option<ErrorCode>> {
+        let err = self.table().get(&err)?;
+
+        if let Some(err) = err.downcast_ref::<std::io::Error>() {
+            return Ok(Some(ErrorCode::from(err)));
+        }
+
+        Ok(None)
+    }
 }
 
 impl<T> crate::bindings::sockets::network::HostNetwork for WasiImpl<T>
@@ -32,8 +45,14 @@ where
 
 impl From<io::Error> for ErrorCode {
     fn from(value: io::Error) -> Self {
+        (&value).into()
+    }
+}
+
+impl From<&io::Error> for ErrorCode {
+    fn from(value: &io::Error) -> Self {
         // Attempt the more detailed native error code first:
-        if let Some(errno) = Errno::from_io_error(&value) {
+        if let Some(errno) = Errno::from_io_error(value) {
             return errno.into();
         }
 
@@ -62,7 +81,13 @@ impl From<io::Error> for ErrorCode {
 
 impl From<Errno> for ErrorCode {
     fn from(value: Errno) -> Self {
-        match value {
+        (&value).into()
+    }
+}
+
+impl From<&Errno> for ErrorCode {
+    fn from(value: &Errno) -> Self {
+        match *value {
             Errno::WOULDBLOCK => ErrorCode::WouldBlock,
             #[allow(unreachable_patterns)] // EWOULDBLOCK and EAGAIN can have the same value.
             Errno::AGAIN => ErrorCode::WouldBlock,
diff --git a/crates/wasi/wit/deps/sockets/network.wit b/crates/wasi/wit/deps/sockets/network.wit
@@ -1,5 +1,8 @@
 @since(version = 0.2.0)
 interface network {
+    @unstable(feature = network-error-code)
+    use wasi:io/error@0.2.1.{error};
+
     /// An opaque resource that represents access to (a subset of) the network.
     /// This enables context-based security for networking.
     /// There is no need for this to map 1:1 to a physical network interface.
@@ -105,6 +108,19 @@ interface network {
         permanent-resolver-failure,
     }
 
+    /// Attempts to extract a network-related `error-code` from the stream
+    /// `error` provided.
+    ///
+    /// Stream operations which return `stream-error::last-operation-failed`
+    /// have a payload with more information about the operation that failed.
+    /// This payload can be passed through to this function to see if there's
+    /// network-related information about the error to return.
+    ///
+    /// Note that this function is fallible because not all stream-related
+    /// errors are network-related errors.
+    @unstable(feature = network-error-code)
+    network-error-code: func(err: borrow<error>) -> option<error-code>;
+
     @since(version = 0.2.0)
     enum ip-address-family {
         /// Similar to `AF_INET` in POSIX.
