Make the fields constructor infallible, and add fields.from-list

crates/test-programs/src/bin/api_proxy.rs

@@ -16,7 +16,7 @@ struct T;
 
 impl bindings::exports::wasi::http::incoming_handler::Guest for T {
  fn handle(_request: IncomingRequest, outparam: ResponseOutparam) {
- let hdrs = bindings::wasi::http::types::Headers::new(&[]);
+ let hdrs = bindings::wasi::http::types::Headers::new();
  let resp = bindings::wasi::http::types::OutgoingResponse::new(200, hdrs);
  let body = resp.body().expect("outgoing response");
 

crates/test-programs/src/bin/api_proxy_streaming.rs

@@ -51,7 +51,7 @@ async fn handle_request(request: IncomingRequest, response_out: ResponseOutparam
 
  let response = OutgoingResponse::new(
  200,
- Fields::new(&[("content-type".to_string(), b"text/plain".to_vec())]),
+ Fields::from_list(&[("content-type".to_string(), b"text/plain".to_vec())]).unwrap(),
  );
 
  let mut body =
@@ -75,12 +75,13 @@ async fn handle_request(request: IncomingRequest, response_out: ResponseOutparam
  (Method::Post, Some("/echo")) => {
  let response = OutgoingResponse::new(
  200,
- Fields::new(
+ Fields::from_list(
  &headers
  .into_iter()
  .filter_map(|(k, v)| (k == "content-type").then_some((k, v)))
  .collect::<Vec<_>>(),
- ),
+ )
+ .unwrap(),
  );
 
  let mut body =
@@ -108,7 +109,7 @@ async fn handle_request(request: IncomingRequest, response_out: ResponseOutparam
  }
 
  _ => {
- let response = OutgoingResponse::new(405, Fields::new(&[]));
+ let response = OutgoingResponse::new(405, Fields::new());
 
  let body = response.body().expect("response should be writable");
 
@@ -137,7 +138,7 @@ async fn hash(url: &Url) -> Result<String> {
  String::new()
  }
  )),
- Fields::new(&[]),
+ Fields::new(),
  );
 
  let response = executor::outgoing_request_send(request).await?;

crates/test-programs/src/bin/http_outbound_request_invalid_header.rs

@@ -1,7 +1,7 @@
 use test_programs::wasi::http::types::{HeaderError, Headers};
 
 fn main() {
- let hdrs = Headers::new(&[]);
+ let hdrs = Headers::new();
  assert!(matches!(
  hdrs.append(&"malformed header name".to_owned(), &b"ok value".to_vec()),
  Err(HeaderError::InvalidSyntax)
@@ -42,4 +42,19 @@ fn main() {
  ),
  Err(HeaderError::Forbidden)
  ));
+
+ assert!(matches!(
+ Headers::from_list(&[("bad header".to_owned(), b"value".to_vec())]),
+ Err(HeaderError::InvalidSyntax)
+ ));
+
+ assert!(matches!(
+ Headers::from_list(&[("custom-forbidden-header".to_owned(), b"value".to_vec())]),
+ Err(HeaderError::Forbidden)
+ ));
+
+ assert!(matches!(
+ Headers::from_list(&[("ok-header-name".to_owned(), b"bad\nvalue".to_vec())]),
+ Err(HeaderError::InvalidSyntax)
+ ));
 }

crates/test-programs/src/bin/http_outbound_request_response_build.rs

@@ -3,10 +3,11 @@ use test_programs::wasi::http::types as http_types;
 fn main() {
  println!("Called _start");
  {
- let headers = http_types::Headers::new(&[(
+ let headers = http_types::Headers::from_list(&[(
  "Content-Type".to_string(),
  "application/json".to_string().into_bytes(),
- )]);
+ )])
+ .unwrap();
  let request = http_types::OutgoingRequest::new(
  &http_types::Method::Get,
  None,
@@ -21,10 +22,11 @@ fn main() {
  .unwrap();
  }
  {
- let headers = http_types::Headers::new(&[(
+ let headers = http_types::Headers::from_list(&[(
  "Content-Type".to_string(),
  "application/text".to_string().into_bytes(),
- )]);
+ )])
+ .unwrap();
  let response = http_types::OutgoingResponse::new(200, headers);
  let outgoing_body = response.body().unwrap();
  let response_body = outgoing_body.write().unwrap();

crates/test-programs/src/http.rs

@@ -42,7 +42,7 @@ pub fn request(
  fn header_val(v: &str) -> Vec<u8> {
  v.to_string().into_bytes()
  }
- let headers = http_types::Headers::new(
+ let headers = http_types::Headers::from_list(
  &[
  &[
  ("User-agent".to_string(), header_val("WASI-HTTP/0.0.1")),
@@ -51,7 +51,7 @@ pub fn request(
  additional_headers.unwrap_or(&[]),
  ]
  .concat(),
- );
+ )?;
 
  let request = http_types::OutgoingRequest::new(
  &method,

crates/wasi-http/src/types_impl.rs

@@ -71,14 +71,38 @@ fn is_forbidden_header<T: WasiHttpView>(view: &mut T, name: &HeaderName) -> bool
 }
 
 impl<T: WasiHttpView> crate::bindings::http::types::HostFields for T {
- fn new(&mut self, entries: Vec<(String, Vec<u8>)>) -> wasmtime::Result<Resource<HostFields>> {
+ fn new(&mut self) -> wasmtime::Result<Resource<HostFields>> {
+ let id = self
+ .table()
+ .push(HostFields::Owned {
+ fields: hyper::HeaderMap::new(),
+ })
+ .context("[new_fields] pushing fields")?;
+
+ Ok(id)
+ }
+
+ fn from_list(
+ &mut self,
+ entries: Vec<(String, Vec<u8>)>,
+ ) -> wasmtime::Result<Result<Resource<HostFields>, HeaderError>> {
  let mut map = hyper::HeaderMap::new();
 
  for (header, value) in entries {
- // This will trap for an invalid header name, but there's no other way to communicate
- // the error out from a constructor.
- let header = hyper::header::HeaderName::from_bytes(header.as_bytes())?;
- let value = hyper::header::HeaderValue::from_bytes(&value)?;
+ let header = match hyper::header::HeaderName::from_bytes(header.as_bytes()) {
+ Ok(header) => header,
+ Err(_) => return Ok(Err(HeaderError::InvalidSyntax)),
+ };
+
+ if is_forbidden_header(self, &header) {
+ return Ok(Err(HeaderError::Forbidden));
+ }
+
+ let value = match hyper::header::HeaderValue::from_bytes(&value) {
+ Ok(value) => value,
+ Err(_) => return Ok(Err(HeaderError::InvalidSyntax)),
+ };
+
  map.append(header, value);
  }
 
@@ -87,7 +111,7 @@ impl<T: WasiHttpView> crate::bindings::http::types::HostFields for T {
  .push(HostFields::Owned { fields: map })
  .context("[new_fields] pushing fields")?;
 
- Ok(id)
+ Ok(Ok(id))
  }
 
  fn drop(&mut self, fields: Resource<HostFields>) -> wasmtime::Result<()> {

crates/wasi-http/wit/deps/http/types.wit

@@ -56,6 +56,9 @@ interface types {
  /// Headers and Trailers.
  resource fields {
 
+ /// Construct an empty HTTP Fields.
+ constructor();
+
  /// Construct an HTTP Fields.
  ///
  /// The list represents each key-value pair in the Fields. Keys
@@ -66,7 +69,12 @@ interface types {
  /// Value, represented as a list of bytes. In a valid Fields, all keys
  /// and values are valid UTF-8 strings. However, values are not always
  /// well-formed, so they are represented as a raw list of bytes.
- constructor(entries: list<tuple<field-key,field-value>>);
+ ///
+ /// An error result will be returned if any header or value was
+ /// syntactically invalid, or if a header was forbidden.
+ from-list: static func(
+ entries: list<tuple<field-key,field-value>>
+ ) -> result<fields, header-error>;
 
  /// Get all of the values corresponding to a key.
  get: func(name: field-key) -> list<field-value>;

crates/wasi/wit/deps/http/types.wit

@@ -56,6 +56,9 @@ interface types {
  /// Headers and Trailers.
  resource fields {
 
+ /// Construct an empty HTTP Fields.
+ constructor();
+
  /// Construct an HTTP Fields.
  ///
  /// The list represents each key-value pair in the Fields. Keys
@@ -66,7 +69,12 @@ interface types {
  /// Value, represented as a list of bytes. In a valid Fields, all keys
  /// and values are valid UTF-8 strings. However, values are not always
  /// well-formed, so they are represented as a raw list of bytes.
- constructor(entries: list<tuple<field-key,field-value>>);
+ ///
+ /// An error result will be returned if any header or value was
+ /// syntactically invalid, or if a header was forbidden.
+ from-list: static func(
+ entries: list<tuple<field-key,field-value>>
+ ) -> result<fields, header-error>;
 
  /// Get all of the values corresponding to a key.
  get: func(name: field-key) -> list<field-value>;