Add default headers to request in router

Spin runtimes are expected to add certain headers to each request as can be seen [here](https://github.com/fermyon/spin/blob/efac5cf2249987b80bcb2c11a76564547df72327/crates/trigger-http/src/lib.rs#L498-L534). The most appropriate place for this to happen in `spin-test` is in the router. However, `wasi:http/types/incoming-request` does not allow for modifying the headers as the headers are set to immutable (and any mutating function called on them returns an `wasi:http/types/header-error.immutable`). This is a rather fundamental shortcoming of `wasi:[email protected]` that we won't be able to get around for the foreseeable future.

To work around the above, we add an optional `incoming-body` to `fermyon:spin-test/http-helper/new-request` which allows the non-body parts of the request to come from the `outgoing-request` while the body comes from the `incoming-request`.

Signed-off-by: Ryan Levick <[email protected]>

crates/router/Cargo.toml

@@ -4,10 +4,12 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+anyhow = { workspace = true }
 bitflags = "2.5.0"
 wit-bindgen-rt = "0.24.0"
 toml = { workspace = true }
 spin-manifest = { workspace = true }
+spin-http = { git = "https://github.com/fermyon/spin", default-features = false }
 
 [lib]
 crate-type = ["cdylib"]

crates/router/src/bindings.rs

@@ -1,5 +1,8 @@
 // Generated by `wit-bindgen` 0.24.0. DO NOT EDIT!
 // Options used:
+pub type OutgoingRequest = wasi::http::types::OutgoingRequest;
+pub type IncomingRequest = wasi::http::types::IncomingRequest;
+pub type IncomingBody = wasi::http::types::IncomingBody;
 #[allow(unused_unsafe, clippy::all)]
 pub fn get_manifest() -> _rt::String {
     unsafe {
@@ -47,6 +50,32 @@ pub fn set_component_id(component_id: &str) {
         wit_import(ptr0.cast_mut(), len0);
     }
 }
+#[allow(unused_unsafe, clippy::all)]
+/// See `fermyon:spin-test/http-helper/new-request` for documentation on this function
+pub fn new_request(
+    request: OutgoingRequest,
+    incoming_body: Option<IncomingBody>,
+) -> IncomingRequest {
+    unsafe {
+        let (result0_0, result0_1) = match &incoming_body {
+            Some(e) => (1i32, (e).take_handle() as i32),
+            None => (0i32, 0i32),
+        };
+        #[cfg(target_arch = "wasm32")]
+        #[link(wasm_import_module = "$root")]
+        extern "C" {
+            #[link_name = "new-request"]
+            fn wit_import(_: i32, _: i32, _: i32) -> i32;
+        }
+
+        #[cfg(not(target_arch = "wasm32"))]
+        fn wit_import(_: i32, _: i32, _: i32) -> i32 {
+            unreachable!()
+        }
+        let ret = wit_import((&request).take_handle() as i32, result0_0, result0_1);
+        wasi::http::types::IncomingRequest::from_handle(ret as u32)
+    }
+}
 #[allow(dead_code)]
 pub mod wasi {
     #[allow(dead_code)]
@@ -7662,21 +7691,21 @@ pub(crate) use __export_router_impl as export;
 #[cfg(target_arch = "wasm32")]
 #[link_section = "component-type:wit-bindgen:0.24.0:router:encoded world"]
 #[doc(hidden)]
-pub static __WIT_BINDGEN_COMPONENT_TYPE: [u8; 6523] = *b"\
-\0asm\x0d\0\x01\0\0\x19\x16wit-component-encoding\x04\0\x07\xfe1\x01A\x02\x01A\x19\
-\x01B\x0a\x04\0\x08pollable\x03\x01\x01h\0\x01@\x01\x04self\x01\0\x7f\x04\0\x16[\
-method]pollable.ready\x01\x02\x01@\x01\x04self\x01\x01\0\x04\0\x16[method]pollab\
-le.block\x01\x03\x01p\x01\x01py\x01@\x01\x02in\x04\0\x05\x04\0\x04poll\x01\x06\x03\
-\x01\x12wasi:io/[email protected]\x05\0\x02\x03\0\0\x08pollable\x01B\x0f\x02\x03\x02\x01\
-\x01\x04\0\x08pollable\x03\0\0\x01w\x04\0\x07instant\x03\0\x02\x01w\x04\0\x08dur\
-ation\x03\0\x04\x01@\0\0\x03\x04\0\x03now\x01\x06\x01@\0\0\x05\x04\0\x0aresoluti\
-on\x01\x07\x01i\x01\x01@\x01\x04when\x03\0\x08\x04\0\x11subscribe-instant\x01\x09\
-\x01@\x01\x04when\x05\0\x08\x04\0\x12subscribe-duration\x01\x0a\x03\x01!wasi:clo\
-cks/monotonic[email protected]\x05\x02\x01B\x04\x04\0\x05error\x03\x01\x01h\0\x01@\x01\
-\x04self\x01\0s\x04\0\x1d[method]error.to-debug-string\x01\x02\x03\x01\x13wasi:i\
-o/error@0.2.0\x05\x03\x02\x03\0\x02\x05error\x01B(\x02\x03\x02\x01\x04\x04\0\x05\
-error\x03\0\0\x02\x03\x02\x01\x01\x04\0\x08pollable\x03\0\x02\x01i\x01\x01q\x02\x15\
-last-operation-failed\x01\x04\0\x06closed\0\0\x04\0\x0cstream-error\x03\0\x05\x04\
+pub static __WIT_BINDGEN_COMPONENT_TYPE: [u8; 6682] = *b"\
+\0asm\x0d\0\x01\0\0\x19\x16wit-component-encoding\x04\0\x07\x9d3\x01A\x02\x01A$\x01\
+B\x0a\x04\0\x08pollable\x03\x01\x01h\0\x01@\x01\x04self\x01\0\x7f\x04\0\x16[meth\
+od]pollable.ready\x01\x02\x01@\x01\x04self\x01\x01\0\x04\0\x16[method]pollable.b\
+lock\x01\x03\x01p\x01\x01py\x01@\x01\x02in\x04\0\x05\x04\0\x04poll\x01\x06\x03\x01\
+\x12wasi:io/[email protected]\x05\0\x02\x03\0\0\x08pollable\x01B\x0f\x02\x03\x02\x01\x01\
+\x04\0\x08pollable\x03\0\0\x01w\x04\0\x07instant\x03\0\x02\x01w\x04\0\x08duratio\
+n\x03\0\x04\x01@\0\0\x03\x04\0\x03now\x01\x06\x01@\0\0\x05\x04\0\x0aresolution\x01\
+\x07\x01i\x01\x01@\x01\x04when\x03\0\x08\x04\0\x11subscribe-instant\x01\x09\x01@\
+\x01\x04when\x05\0\x08\x04\0\x12subscribe-duration\x01\x0a\x03\x01!wasi:clocks/m\
+onotonic[email protected]\x05\x02\x01B\x04\x04\0\x05error\x03\x01\x01h\0\x01@\x01\x04\
+self\x01\0s\x04\0\x1d[method]error.to-debug-string\x01\x02\x03\x01\x13wasi:io/er\
+ror@0.2.0\x05\x03\x02\x03\0\x02\x05error\x01B(\x02\x03\x02\x01\x04\x04\0\x05erro\
+r\x03\0\0\x02\x03\x02\x01\x01\x04\0\x08pollable\x03\0\x02\x01i\x01\x01q\x02\x15l\
+ast-operation-failed\x01\x04\0\x06closed\0\0\x04\0\x0cstream-error\x03\0\x05\x04\
 \0\x0cinput-stream\x03\x01\x04\0\x0doutput-stream\x03\x01\x01h\x07\x01p}\x01j\x01\
 \x0a\x01\x06\x01@\x02\x04self\x09\x03lenw\0\x0b\x04\0\x19[method]input-stream.re\
 ad\x01\x0c\x04\0\"[method]input-stream.blocking-read\x01\x0c\x01j\x01w\x01\x06\x01\
@@ -7785,14 +7814,17 @@ e\x01\x8c\x01\x03\x01\x15wasi:http/[email protected]\x05\x09\x02\x03\0\x04\x10incoming
 -request\x02\x03\0\x04\x11response-outparam\x01B\x08\x02\x03\x02\x01\x0a\x04\0\x10\
 incoming-request\x03\0\0\x02\x03\x02\x01\x0b\x04\0\x11response-outparam\x03\0\x02\
 \x01i\x01\x01i\x03\x01@\x02\x07request\x04\x0cresponse-out\x05\x01\0\x04\0\x06ha\
-ndle\x01\x06\x03\x01\x20wasi:http/[email protected]\x05\x0c\x01@\0\0s\x03\0\
-\x0cget-manifest\x01\x0d\x01@\x01\x0ccomponent-ids\x01\0\x03\0\x10set-component-\
-id\x01\x0e\x01B\x08\x02\x03\x02\x01\x0a\x04\0\x10incoming-request\x03\0\0\x02\x03\
-\x02\x01\x0b\x04\0\x11response-outparam\x03\0\x02\x01i\x01\x01i\x03\x01@\x02\x07\
-request\x04\x0cresponse-out\x05\x01\0\x04\0\x06handle\x01\x06\x04\x01\x20wasi:ht\
-tp/[email protected]\x05\x0f\x04\x01\x15fermyon:router/router\x04\0\x0b\x0c\
-\x01\0\x06router\x03\0\0\0G\x09producers\x01\x0cprocessed-by\x02\x0dwit-componen\
-t\x070.202.0\x10wit-bindgen-rust\x060.24.0";
+ndle\x01\x06\x03\x01\x20wasi:http/[email protected]\x05\x0c\x02\x03\0\x04\x10\
+outgoing-request\x03\0\x10outgoing-request\x03\0\x0d\x03\0\x10incoming-request\x03\
+\0\x0a\x02\x03\0\x04\x0dincoming-body\x03\0\x0dincoming-body\x03\0\x10\x01@\0\0s\
+\x03\0\x0cget-manifest\x01\x12\x01@\x01\x0ccomponent-ids\x01\0\x03\0\x10set-comp\
+onent-id\x01\x13\x01i\x0e\x01i\x11\x01k\x15\x01i\x0f\x01@\x02\x07request\x14\x0d\
+incoming-body\x16\0\x17\x03\0\x0bnew-request\x01\x18\x01B\x08\x02\x03\x02\x01\x0a\
+\x04\0\x10incoming-request\x03\0\0\x02\x03\x02\x01\x0b\x04\0\x11response-outpara\
+m\x03\0\x02\x01i\x01\x01i\x03\x01@\x02\x07request\x04\x0cresponse-out\x05\x01\0\x04\
+\0\x06handle\x01\x06\x04\x01\x20wasi:http/[email protected]\x05\x19\x04\x01\
+\x15fermyon:router/router\x04\0\x0b\x0c\x01\0\x06router\x03\0\0\0G\x09producers\x01\
+\x0cprocessed-by\x02\x0dwit-component\x070.202.0\x10wit-bindgen-rust\x060.24.0";
 
 #[inline(never)]
 #[doc(hidden)]

crates/router/src/lib.rs

@@ -1,14 +1,13 @@
 #[allow(warnings)]
 mod bindings;
 
+use anyhow::Context as _;
 use bindings::{
-    exports::wasi::http::incoming_handler::{IncomingRequest, ResponseOutparam},
-    wasi::http::types::ErrorCode,
-};
-
-use crate::bindings::{
     exports::wasi::http::incoming_handler::Guest,
     wasi::http::incoming_handler::handle as downstream,
+    wasi::http::types::{
+        ErrorCode, Headers, IncomingRequest, OutgoingRequest, ResponseOutparam, Scheme,
+    },
 };
 
 struct Component;
@@ -46,11 +45,20 @@ impl Guest for Component {
             .split_once('?')
             .map(|(path, _)| path)
             .unwrap_or(&path_with_query);
-        let component_id = routes
+        let routing = routes
             .iter()
-            .find(|(route, _)| path.starts_with(route) || *route == "/...")
-            .map(|(_, comp)| comp);
-        if let Some(component_id) = component_id {
+            .find(|(route, _)| path.starts_with(route) || *route == "/...");
+        if let Some((route, component_id)) = routing {
+            let request = match apply_request_transformations(request, (*route).to_owned()) {
+                Ok(request) => request,
+                Err(e) => {
+                    ResponseOutparam::set(
+                        response_out,
+                        Err(ErrorCode::InternalError(Some(e.to_string()))),
+                    );
+                    return;
+                }
+            };
             bindings::set_component_id(component_id);
             downstream(request, response_out)
         } else {
@@ -65,4 +73,83 @@ impl Guest for Component {
     }
 }
 
+/// Apply any request transformations needed for the given route.
+fn apply_request_transformations(
+    request: IncomingRequest,
+    raw_route: String,
+) -> anyhow::Result<IncomingRequest> {
+    let headers_to_add = calculate_default_headers(&request, raw_route)
+        .context("could not calculate default headers to for request")?
+        .into_iter()
+        .flat_map(|(k, v)| {
+            k.iter()
+                .map(move |s| (s.to_string(), v.clone().into_bytes()))
+        })
+        .chain(request.headers().entries());
+    let headers = Headers::new();
+    for (key, value) in headers_to_add {
+        headers.append(&key, &value).unwrap();
+    }
+    let new = OutgoingRequest::new(headers);
+    let _ = new.set_scheme(request.scheme().as_ref());
+    let _ = new.set_authority(request.authority().as_deref());
+    let _ = new.set_method(&request.method());
+    let _ = new.set_path_with_query(request.path_with_query().as_deref());
+    Ok(bindings::new_request(new, Some(request.consume().unwrap())))
+}
+
+const FULL_URL: &[&str] = &["SPIN-FULL-URL", "X-FULL-URL"];
+const PATH_INFO: &[&str] = &["SPIN-PATH-INFO", "PATH-INFO"];
+const MATCHED_ROUTE: &[&str] = &["SPIN-MATCHED-ROUTE", "X-MATCHED-ROUTE"];
+const COMPONENT_ROUTE: &[&str] = &["SPIN-COMPONENT-ROUTE", "X-COMPONENT-ROUTE"];
+const RAW_COMPONENT_ROUTE: &[&str] = &["SPIN-RAW-COMPONENT-ROUTE", "X-RAW-COMPONENT-ROUTE"];
+const BASE_PATH: &[&str] = &["SPIN-BASE-PATH", "X-BASE-PATH"];
+const CLIENT_ADDR: &[&str] = &["SPIN-CLIENT-ADDR", "X-CLIENT-ADDR"];
+/// Calculate the default headers for the given request.
+fn calculate_default_headers<'a>(
+    req: &IncomingRequest,
+    raw_route: String,
+) -> anyhow::Result<Vec<(&'a [&'a str], String)>> {
+    let mut res = vec![];
+    // TODO: calculate base path from manifest
+    let base = "/".to_owned();
+    let abs_path = req.path_with_query().context("cannot get path and query")?;
+    let scheme = req.scheme();
+    let scheme = match scheme.as_ref().unwrap_or(&Scheme::Https) {
+        Scheme::Http => "http",
+        Scheme::Https => "https",
+        Scheme::Other(s) => s,
+    };
+    let host = req
+        .headers()
+        .get(&"host".to_owned())
+        .into_iter()
+        .find(|v| !v.is_empty())
+        .map(String::from_utf8)
+        .transpose()
+        .context("expected 'host' header to be UTF-8 encoded but it was not")?
+        .unwrap_or_else(|| "localhost".to_owned());
+
+    let matched_route =
+        spin_http::routes::RoutePattern::sanitize_with_base(base.clone(), raw_route.clone());
+
+    let path_info = spin_http::routes::RoutePattern::from(base.clone(), raw_route.clone())
+        .relative(&abs_path)?;
+    let full_url = format!("{}://{}{}", scheme, host, abs_path);
+    let component_route = raw_route
+        .strip_suffix("/...")
+        .unwrap_or(&raw_route)
+        .to_owned();
+
+    res.push((PATH_INFO, path_info));
+    res.push((FULL_URL, full_url));
+    res.push((MATCHED_ROUTE, matched_route));
+    res.push((BASE_PATH, base));
+    res.push((RAW_COMPONENT_ROUTE, raw_route));
+    res.push((COMPONENT_ROUTE, component_route));
+    res.push((CLIENT_ADDR, "127.0.0.1:0".to_owned()));
+
+    Ok(res)
+}
+
 bindings::export!(Component with_types_in bindings);

crates/router/wit/world.wit

@@ -6,4 +6,8 @@ world router {
     import wasi:http/incoming-handler@0.2.0;
     import get-manifest: func() -> string;
     import set-component-id: func(component-id: string);
+
+    use wasi:http/types@0.2.0.{outgoing-request, incoming-request, incoming-body};
+    /// See `fermyon:spin-test/http-helper/new-request` for documentation on this function
+    import new-request: func(request: outgoing-request, incoming-body: option<incoming-body>) -> incoming-request;
 }

crates/spin-test-sdk/src/lib.rs

@@ -16,7 +16,7 @@ use bindings::wasi::http;
 
 /// Make a request to the Spin app and return the response.
 pub fn perform_request(request: http::types::OutgoingRequest) -> http::types::IncomingResponse {
-    let request = spin_test::http_helper::new_request(request);
+    let request = spin_test::http_helper::new_request(request, None);
     let (response_out, response_receiver) = spin_test::http_helper::new_response();
     http::incoming_handler::handle(request, response_out);
     response_receiver.get().unwrap()

host-wit/world.wit

@@ -30,14 +30,18 @@ world runner {
 interface http-helper {
     use wasi:http/types@0.2.0.{
         incoming-request, incoming-response, outgoing-response,
-        outgoing-request, response-outparam, future-incoming-response
+        outgoing-request, response-outparam, future-incoming-response,
+        incoming-body
     };
     /// A receiver of an `incoming-response`
     resource response-receiver {
         get: func() -> option<incoming-response>;
     }
     /// Create an `incoming-request` from an `outgoing-request`
-    new-request: func(request: outgoing-request) -> incoming-request;
+    ///
+    /// An optional `incoming-body` can also be supplied which will be
+    /// used instead of the body of the `outgoing-request`.
+    new-request: func(request: outgoing-request, incoming-body: option<incoming-body>) -> incoming-request;
     /// Get a pair of a `response-outparam` and a `response-receiver`
     new-response: func() -> tuple<response-outparam, response-receiver>;
     /// Create a `future-incoming-response` from an `outgoing-response`