Commit-Boost · ltitanb · Sep 15, 2025 · Sep 12, 2025 · Sep 12, 2025 · Sep 12, 2025
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/crates/common/src/config/mod.rs b/crates/common/src/config/mod.rs
@@ -1,6 +1,6 @@
 use std::path::PathBuf;
 
-use eyre::Result;
+use eyre::{Result, bail};
 use serde::{Deserialize, Serialize};
 
 use crate::types::{Chain, ChainLoader, ForkVersion, load_chain_from_file};
@@ -45,6 +45,13 @@ impl CommitBoostConfig {
         if let Some(signer) = &self.signer {
             signer.validate().await?;
         }
+
+        if self.relays.iter().any(|r| r.validator_registration_batch_size.is_some()) {
+            bail!(
+                "validator_registration_batch_size is now obsolete on a per-relay basis. Please use validator_registration_batch_size in the [pbs] section instead"
+            )
+        }
+
         Ok(())
     }
 

diff --git a/crates/common/src/config/pbs.rs b/crates/common/src/config/pbs.rs
@@ -36,6 +36,7 @@ use crate::{
 };
 
 #[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(deny_unknown_fields)]
 pub struct RelayConfig {
     /// Relay ID, if missing will default to the URL hostname from the entry
     pub id: Option<String>,
@@ -128,6 +129,10 @@ pub struct PbsConfig {
     /// Maximum number of retries for validator registration request per relay
     #[serde(default = "default_u32::<REGISTER_VALIDATOR_RETRY_LIMIT>")]
     pub register_validator_retry_limit: u32,
+    /// Maximum number of validators to send to relays in a single registration
+    /// request
+    #[serde(deserialize_with = "empty_string_as_none", default)]
+    pub validator_registration_batch_size: Option<usize>,
 }
 
 impl PbsConfig {

diff --git a/crates/pbs/Cargo.toml b/crates/pbs/Cargo.toml
@@ -18,6 +18,7 @@ lazy_static.workspace = true
 parking_lot.workspace = true
 prometheus.workspace = true
 reqwest.workspace = true
+serde.workspace = true
 serde_json.workspace = true
 tokio.workspace = true
 tower-http.workspace = true

diff --git a/crates/pbs/src/api.rs b/crates/pbs/src/api.rs
@@ -1,4 +1,3 @@
-use alloy::rpc::types::beacon::relay::ValidatorRegistration;
 use async_trait::async_trait;
 use axum::{Router, http::HeaderMap};
 use cb_common::pbs::{
@@ -45,7 +44,7 @@ pub trait BuilderApi<S: BuilderApiState>: 'static {
 
     /// https://ethereum.github.io/builder-specs/#/Builder/registerValidator
     async fn register_validator(
-        registrations: Vec<ValidatorRegistration>,
+        registrations: Vec<serde_json::Value>,
         req_headers: HeaderMap,
         state: PbsState<S>,
     ) -> eyre::Result<()> {

diff --git a/crates/pbs/src/mev_boost/register_validator.rs b/crates/pbs/src/mev_boost/register_validator.rs
@@ -1,14 +1,14 @@
 use std::time::{Duration, Instant};
 
-use alloy::rpc::types::beacon::relay::ValidatorRegistration;
+use alloy::primitives::Bytes;
 use axum::http::{HeaderMap, HeaderValue};
 use cb_common::{
     pbs::{HEADER_START_TIME_UNIX_MS, RelayClient, error::PbsError},
     utils::{get_user_agent_with_version, read_chunked_body_with_max, utcnow_ms},
 };
 use eyre::bail;
 use futures::future::{join_all, select_ok};
-use reqwest::header::USER_AGENT;
+use reqwest::header::{CONTENT_TYPE, USER_AGENT};
 use tracing::{Instrument, debug, error};
 use url::Url;
 
@@ -21,7 +21,7 @@ use crate::{
 /// Implements https://ethereum.github.io/builder-specs/#/Builder/registerValidator
 /// Returns 200 if at least one relay returns 200, else 503
 pub async fn register_validator<S: BuilderApiState>(
-    registrations: Vec<ValidatorRegistration>,
+    registrations: Vec<serde_json::Value>,
     req_headers: HeaderMap,
     state: PbsState<S>,
 ) -> eyre::Result<()> {
@@ -31,27 +31,29 @@ pub async fn register_validator<S: BuilderApiState>(
         .insert(HEADER_START_TIME_UNIX_MS, HeaderValue::from_str(&utcnow_ms().to_string())?);
     send_headers.insert(USER_AGENT, get_user_agent_with_version(&req_headers)?);
 
-    let relays = state.all_relays().to_vec();
-    let mut handles = Vec::with_capacity(relays.len());
-    for relay in relays.clone() {
-        if let Some(batch_size) = relay.config.validator_registration_batch_size {
-            for batch in registrations.chunks(batch_size) {
-                handles.push(tokio::spawn(
-                    send_register_validator_with_timeout(
-                        batch.to_vec(),
-                        relay.clone(),
-                        send_headers.clone(),
-                        state.pbs_config().timeout_register_validator_ms,
-                        state.pbs_config().register_validator_retry_limit,
-                    )
-                    .in_current_span(),
-                ));
-            }
+    // prepare the body in advance, ugly dyn
+    let bodies: Box<dyn Iterator<Item = (usize, Bytes)>> =
+        if let Some(batch_size) = state.config.pbs_config.validator_registration_batch_size {
+            Box::new(registrations.chunks(batch_size).map(|batch| {
+                // SAFETY: unwrap is ok because we're serializing a &[serde_json::Value]
+                let body = serde_json::to_vec(batch).unwrap();
+                (batch.len(), Bytes::from(body))
+            }))
         } else {
+            let body = serde_json::to_vec(&registrations).unwrap();
+            Box::new(std::iter::once((registrations.len(), Bytes::from(body))))
+        };
+    send_headers.insert(CONTENT_TYPE, HeaderValue::from_static("application/json"));
+
+    let mut handles = Vec::with_capacity(state.all_relays().len());
+
+    for (n_regs, body) in bodies {
+        for relay in state.all_relays().iter().cloned() {
             handles.push(tokio::spawn(
                 send_register_validator_with_timeout(
-                    registrations.clone(),
-                    relay.clone(),
+                    n_regs,
+                    body.clone(),
+                    relay,
                     send_headers.clone(),
                     state.pbs_config().timeout_register_validator_ms,
                     state.pbs_config().register_validator_retry_limit,
@@ -82,7 +84,8 @@ pub async fn register_validator<S: BuilderApiState>(
 /// Register validator to relay, retry connection errors until the
 /// given timeout has passed
 async fn send_register_validator_with_timeout(
-    registrations: Vec<ValidatorRegistration>,
+    n_regs: usize,
+    body: Bytes,
     relay: RelayClient,
     headers: HeaderMap,
     timeout_ms: u64,
@@ -97,7 +100,8 @@ async fn send_register_validator_with_timeout(
         let start_request = Instant::now();
         match send_register_validator(
             url.clone(),
-            &registrations,
+            n_regs,
+            body.clone(),
             &relay,
             headers.clone(),
             remaining_timeout_ms,
@@ -134,7 +138,8 @@ async fn send_register_validator_with_timeout(
 
 async fn send_register_validator(
     url: Url,
-    registrations: &[ValidatorRegistration],
+    n_regs: usize,
+    body: Bytes,
     relay: &RelayClient,
     headers: HeaderMap,
     timeout_ms: u64,
@@ -146,7 +151,7 @@ async fn send_register_validator(
         .post(url)
         .timeout(Duration::from_millis(timeout_ms))
         .headers(headers)
-        .json(&registrations)
+        .body(body.0)
         .send()
         .await
     {
@@ -189,7 +194,7 @@ async fn send_register_validator(
         retry,
         ?code,
         latency = ?request_latency,
-        num_registrations = registrations.len(),
+        num_registrations = n_regs,
         "registration successful"
     );
 

diff --git a/crates/pbs/src/routes/register_validator.rs b/crates/pbs/src/routes/register_validator.rs
@@ -1,4 +1,3 @@
-use alloy::rpc::types::beacon::relay::ValidatorRegistration;
 use axum::{Json, extract::State, http::HeaderMap, response::IntoResponse};
 use cb_common::utils::get_user_agent;
 use reqwest::StatusCode;
@@ -15,7 +14,7 @@ use crate::{
 pub async fn handle_register_validator<S: BuilderApiState, A: BuilderApi<S>>(
     State(state): State<PbsStateGuard<S>>,
     req_headers: HeaderMap,
-    Json(registrations): Json<Vec<ValidatorRegistration>>,
+    Json(registrations): Json<Vec<serde_json::Value>>,
 ) -> Result<impl IntoResponse, PbsClientError> {
     let state = state.read().clone();
 

diff --git a/tests/src/utils.rs b/tests/src/utils.rs
@@ -81,6 +81,7 @@ pub fn get_pbs_static_config(port: u16) -> PbsConfig {
         rpc_url: None,
         http_timeout_seconds: 10,
         register_validator_retry_limit: u32::MAX,
+        validator_registration_batch_size: None,
     }
 }
 

diff --git a/tests/tests/pbs_post_validators.rs b/tests/tests/pbs_post_validators.rs
@@ -61,146 +61,6 @@ async fn test_register_validators() -> Result<()> {
     Ok(())
 }
 
-#[tokio::test]
-async fn test_register_validators_returns_422_if_request_is_malformed() -> Result<()> {
-    setup_test_env();
-    let signer = random_secret();
-    let pubkey: BlsPublicKey = signer.public_key();
-
-    let chain = Chain::Holesky;
-    let pbs_port = 4100;
-
-    // Run a mock relay
-    let relays = vec![generate_mock_relay(pbs_port + 1, pubkey)?];
-    let mock_state = Arc::new(MockRelayState::new(chain, signer));
-    tokio::spawn(start_mock_relay_service(mock_state.clone(), pbs_port + 1));
-
-    // Run the PBS service
-    let config = to_pbs_config(chain, get_pbs_static_config(pbs_port), relays);
-    let state = PbsState::new(config);
-    tokio::spawn(PbsService::run::<(), DefaultBuilderApi>(state));
-
-    // leave some time to start servers
-    tokio::time::sleep(Duration::from_millis(100)).await;
-
-    let mock_validator = MockValidator::new(pbs_port)?;
-    let url = mock_validator.comm_boost.register_validator_url().unwrap();
-    info!("Sending register validator");
-
-    // Bad fee recipient
-    let bad_json = r#"[{
-        "message": {
-            "fee_recipient": "0xaa",
-            "gas_limit": "100000",
-            "timestamp": "1000000",
-            "pubkey": "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
-        },
-        "signature": "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"
-    }]"#;
-
-    let res = mock_validator
-        .comm_boost
-        .client
-        .post(url.clone())
-        .header("Content-Type", "application/json")
-        .body(bad_json)
-        .send()
-        .await?;
-
-    assert_eq!(res.status(), StatusCode::UNPROCESSABLE_ENTITY);
-
-    // Bad pubkey
-    let bad_json = r#"[{
-        "message": {
-            "fee_recipient": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
-            "gas_limit": "100000",
-            "timestamp": "1000000",
-            "pubkey": "0xbbb"
-        },
-        "signature": "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"
-    }]"#;
-
-    let res = mock_validator
-        .comm_boost
-        .client
-        .post(url.clone())
-        .header("Content-Type", "application/json")
-        .body(bad_json)
-        .send()
-        .await?;
-
-    assert_eq!(res.status(), StatusCode::UNPROCESSABLE_ENTITY);
-
-    // Bad signature
-    let bad_json = r#"[{
-        "message": {
-            "fee_recipient": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
-            "gas_limit": "100000",
-            "timestamp": "1000000",
-            "pubkey": "0xbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
-        },
-        "signature": "0xcccc"
-    }]"#;
-
-    let res = mock_validator
-        .comm_boost
-        .client
-        .post(url.clone())
-        .header("Content-Type", "application/json")
-        .body(bad_json)
-        .send()
-        .await?;
-
-    assert_eq!(res.status(), StatusCode::UNPROCESSABLE_ENTITY);
-
-    // gas limit too high
-    let bad_json = r#"[{
-        "message": {
-            "fee_recipient": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
-            "gas_limit": "10000000000000000000000000000000000000000000000000000000",
-            "timestamp": "1000000",
-            "pubkey": "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"
-        },
-        "signature": "0xcccc"
-    }]"#;
-
-    let res = mock_validator
-        .comm_boost
-        .client
-        .post(url.clone())
-        .header("Content-Type", "application/json")
-        .body(bad_json)
-        .send()
-        .await?;
-
-    assert_eq!(res.status(), StatusCode::UNPROCESSABLE_ENTITY);
-
-    // timestamp too high
-    let bad_json = r#"[{
-            "message": {
-                "fee_recipient": "0xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
-                "gas_limit": "1000000",
-                "timestamp": "10000000000000000000000000000000000000000000000000000000",
-                "pubkey": "0xcccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"
-            },
-            "signature": "0xcccc"
-        }]"#;
-
-    let res = mock_validator
-        .comm_boost
-        .client
-        .post(url.clone())
-        .header("Content-Type", "application/json")
-        .body(bad_json)
-        .send()
-        .await?;
-
-    assert_eq!(res.status(), StatusCode::UNPROCESSABLE_ENTITY);
-
-    assert_eq!(mock_state.received_register_validator(), 0);
-    Ok(())
-}
-
 #[tokio::test]
 async fn test_register_validators_does_not_retry_on_429() -> Result<()> {
     setup_test_env();