Rewrite get_header relay communication to support SSZ and JSON

content negotiation. Includes:

- SSZ and JSON encoding/decoding for relay get_header responses
- Content-Type and Eth-Consensus-Version header parsing
- Accept header forwarding to relays with q-value ordering
- MIME parameter tolerance on relay response Content-Type
- Fork-aware SSZ bid value extraction for all supported forks
- Mock relay and validator SSZ support in test infrastructure
- get_header integration tests for both encodings
- Dynamic port allocation in tests via get_free_listener

Author: JasonVranek

Cargo.lock

@@ -15,6 +15,9 @@ pub enum PbsError {
     #[error("json decode error: {err:?}, raw: {raw}")]
     JsonDecode { err: serde_json::Error, raw: String },
 
+    #[error("ssz decode error: {err:?}, fork: {fork}")]
+    SSZDecode { err: String, fork: ForkName },
+
     #[error("{0}")]
     ReadResponse(#[from] ResponseReadError),
 

crates/common/src/pbs/error.rs

@@ -10,7 +10,7 @@ use lh_types::{BeaconBlock, ForkName};
 use mediatype::{MediaType, ReadParams};
 use reqwest::{
     Response,
-    header::{ACCEPT, CONTENT_TYPE, HeaderMap},
+    header::{ACCEPT, CONTENT_TYPE, HeaderMap, ToStrError},
 };
 use thiserror::Error;
 
@@ -37,6 +37,18 @@ pub enum ResponseReadError {
     NonSuccess { status_code: u16, error_msg: String, request_url: String },
 }
 
+#[derive(Debug, Error)]
+pub enum AcceptedEncodingsError {
+    #[error("invalid header string: {0}")]
+    InvalidString(#[from] ToStrError),
+
+    #[error("invalid accept header: {error_msg}")]
+    InvalidEncoding { error_msg: String },
+
+    #[error("unsupported accept type")]
+    UnsupportedAcceptType,
+}
+
 #[cfg(feature = "testing-flags")]
 thread_local! {
     static IGNORE_CONTENT_LENGTH: Cell<bool> = const { Cell::new(false) };
@@ -108,7 +120,7 @@ pub async fn read_chunked_body_with_max(
 /// Reads an HTTP response body with a size limit, erroring on non-success
 /// status or read failure.
 pub async fn safe_read_http_response(
-    response: reqwest::Response,
+    response: Response,
     max_size: usize,
 ) -> Result<Vec<u8>, ResponseReadError> {
     let status_code = response.status();
@@ -198,16 +210,22 @@ impl IntoIterator for AcceptedEncodings {
 /// The returned order honors the RFC 9110 §12.5.1 precedence rules already
 /// applied by `headers_accept::Accept::media_types()` (specificity, then
 /// q-value, then original order).
-pub fn get_accept_types(req_headers: &HeaderMap) -> eyre::Result<AcceptedEncodings> {
+pub fn get_accept_types(
+    req_headers: &HeaderMap,
+) -> Result<AcceptedEncodings, AcceptedEncodingsError> {
     // Only two supported media types, so the ordered set is at most two
     // entries: primary + optional fallback.
     let mut primary: Option<EncodingType> = None;
     let mut fallback: Option<EncodingType> = None;
     let mut saw_any = false;
     let mut had_supported = false;
     for header in req_headers.get_all(ACCEPT).iter() {
-        let accept = Accept::from_str(header.to_str()?)
-            .map_err(|e| eyre::eyre!("invalid accept header: {e}"))?;
+        let accept_str = header.to_str().map_err(AcceptedEncodingsError::InvalidString)?;
+        let accept =
+            Accept::from_str(accept_str).map_err(|e| AcceptedEncodingsError::InvalidEncoding {
+                error_msg: (format!("invalid accept header: {e}")).to_string(),
+            })?;
+
         for mt in accept.media_types() {
             saw_any = true;
 
@@ -243,7 +261,7 @@ pub fn get_accept_types(req_headers: &HeaderMap) -> eyre::Result<AcceptedEncodin
     }
 
     if saw_any && !had_supported {
-        eyre::bail!("unsupported accept type");
+        return Err(AcceptedEncodingsError::UnsupportedAcceptType)
     }
 
     // No accept header (or only q=0 rejections): fall back to the request

crates/common/src/wire.rs

@@ -1,5 +1,8 @@
-use axum::{http::StatusCode, response::IntoResponse};
-use cb_common::wire::BodyDeserializeError;
+use axum::{
+    http::StatusCode,
+    response::{IntoResponse, Response},
+};
+use cb_common::wire::{AcceptedEncodingsError, BodyDeserializeError};
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -13,6 +16,8 @@ pub enum PbsClientError {
     Internal,
     #[error("failed to deserialize body: {0}")]
     DecodeError(#[from] BodyDeserializeError),
+    #[error("invalid accept types: {0}")]
+    HeaderError(#[from] AcceptedEncodingsError),
 }
 
 impl PbsClientError {
@@ -22,17 +27,19 @@ impl PbsClientError {
             PbsClientError::NoPayload => StatusCode::BAD_GATEWAY,
             PbsClientError::Internal => StatusCode::INTERNAL_SERVER_ERROR,
             PbsClientError::DecodeError(_) => StatusCode::BAD_REQUEST,
+            PbsClientError::HeaderError(_) => StatusCode::BAD_REQUEST,
         }
     }
 }
 
 impl IntoResponse for PbsClientError {
-    fn into_response(self) -> axum::response::Response {
+    fn into_response(self) -> Response {
         let msg = match &self {
             PbsClientError::NoResponse => "no response from relays".to_string(),
             PbsClientError::NoPayload => "no payload from relays".to_string(),
             PbsClientError::Internal => "internal server error".to_string(),
             PbsClientError::DecodeError(e) => format!("error decoding request: {e}"),
+            PbsClientError::HeaderError(e) => format!("header error: {e}"),
         };
 
         (self.status_code(), msg).into_response()