feat: add the ability to set GET parameters in relayer calls

benches/pbs/src/main.rs

@@ -157,6 +157,7 @@ fn get_mock_validator(bench: BenchConfig) -> RelayClient {
         entry,
         id: None,
         headers: None,
+        get_params: None,
         enable_timing_games: false,
         target_first_request_ms: None,
         frequency_get_header_ms: None,

config.example.toml

@@ -66,6 +66,9 @@ url = "http://0xa1cec75a3f0661e99299274182938151e8433c61a19222347ea1313d839229cb
 # Headers to send with each request for this relay
 # OPTIONAL
 headers = { X-MyCustomHeader = "MyCustomValue" }
+# GET parameters to add to each request URL for this relay
+# OPTIONAL
+get_params = { param1 = "value1", param2 = "value2" }
 # Whether to enable timing games, as tuned by `target_first_request_ms` and `frequency_get_header_ms`.
 # These values should be carefully chosen for each relay, as each relay has different latency and timing games setups.
 # They should only be used by advanced users, and if mis-configured can result in unforeseen effects, e.g. fetching a lower header value,
@@ -130,7 +133,7 @@ timeout_get_header_ms = 900
 late_in_slot_time_ms = 1500
 # For each mux, one or more [[mux.relays]] can be defined, which will be used for the matching validator pubkeys
 # Only the relays defined here will be used, and the relays defined in the main [[relays]] config will be ignored
-# The fields specified here are the same as in [[relays]] (headers, enable_timing_games, target_first_request_ms, frequency_get_header_ms)
+# The fields specified here are the same as in [[relays]] (headers, get_params, enable_timing_games, target_first_request_ms, frequency_get_header_ms)
 [[mux.relays]]
 id = "mux-relay-1"
 url = "http://0xa119589bb33ef52acbb8116832bec2b58fca590fe5c85eac5d3230b44d5bc09fe73ccd21f88eab31d6de16194d17782e@def.xyz"

crates/common/src/config/pbs.rs

@@ -43,6 +43,8 @@ pub struct RelayConfig {
     pub entry: RelayEntry,
     /// Optional headers to send with each request
     pub headers: Option<HashMap<String, String>>,
+    /// Optional GET parameters to add to each request
+    pub get_params: Option<HashMap<String, String>>,
     /// Whether to enable timing games
     #[serde(default = "default_bool::<false>")]
     pub enable_timing_games: bool,

crates/common/src/pbs/relay.rs

@@ -90,7 +90,16 @@ impl RelayClient {
 
     // URL builders
     pub fn get_url(&self, path: &str) -> Result<Url, PbsError> {
-        self.config.entry.url.join(path).map_err(PbsError::UrlParsing)
+        let mut url = self.config.entry.url.join(path).map_err(PbsError::UrlParsing)?;
+
+        if let Some(get_params) = &self.config.get_params {
+            let mut query_pairs = url.query_pairs_mut();
+            for (key, value) in get_params {
+                query_pairs.append_pair(key, value);
+            }
+        }
+
+        Ok(url)
     }
     pub fn builder_api_url(&self, path: &str) -> Result<Url, PbsError> {
         self.get_url(&format!("{BUILDER_API_PATH}{path}"))
@@ -120,6 +129,8 @@ impl RelayClient {
 
 #[cfg(test)]
 mod tests {
+    use std::collections::HashMap;
+
     use alloy::{
         primitives::{hex::FromHex, B256},
         rpc::types::beacon::BlsPublicKey,
@@ -172,4 +183,33 @@ mod tests {
             expected
         );
     }
+
+    #[test]
+    fn test_relay_url_with_get_params() {
+        let slot = 0;
+        let parent_hash = B256::ZERO;
+        let validator_pubkey = BlsPublicKey::ZERO;
+        // Note: HashMap iteration order is not guaranteed, so we can't predict the
+        // exact order of parameters Instead of hard-coding the order, we'll
+        // check that both parameters are present in the URL
+        let url_prefix = format!("http://0xa1cec75a3f0661e99299274182938151e8433c61a19222347ea1313d839229cb4ce4e3e5aa2bdeb71c8fcf1b084963c2@abc.xyz/eth/v1/builder/header/{slot}/{parent_hash}/{validator_pubkey}?");
+
+        let mut get_params = HashMap::new();
+        get_params.insert("param1".to_string(), "value1".to_string());
+        get_params.insert("param2".to_string(), "value2".to_string());
+
+        let relay_config = r#"
+        {
+            "url": "http://0xa1cec75a3f0661e99299274182938151e8433c61a19222347ea1313d839229cb4ce4e3e5aa2bdeb71c8fcf1b084963c2@abc.xyz"
+        }"#;
+
+        let mut config = serde_json::from_str::<RelayConfig>(relay_config).unwrap();
+        config.get_params = Some(get_params);
+        let relay = RelayClient::new(config).unwrap();
+
+        let url = relay.get_header_url(slot, parent_hash, validator_pubkey).unwrap().to_string();
+        assert!(url.starts_with(&url_prefix));
+        assert!(url.contains("param1=value1"));
+        assert!(url.contains("param2=value2"));
+    }
 }

tests/src/utils.rs

@@ -29,6 +29,7 @@ pub fn generate_mock_relay(port: u16, pubkey: BlsPublicKey) -> Result<RelayClien
         entry,
         id: None,
         headers: None,
+        get_params: None,
         enable_timing_games: false,
         target_first_request_ms: None,
         frequency_get_header_ms: None,
@@ -48,6 +49,7 @@ pub fn generate_mock_relay_with_batch_size(
         entry,
         id: None,
         headers: None,
+        get_params: None,
         enable_timing_games: false,
         target_first_request_ms: None,
         frequency_get_header_ms: None,