Remove deprecated HeaderStartTimeUnixMS (#749)

- Remove HeaderStartTimeUnixMS constant from constants.go
- Remove HeaderStartTimeUnixMS from getHeader and processPayload methods
- Fully transition to using HeaderDateMilliseconds for request timing

Co-authored-by: Justin Traglia <[email protected]>

Author: alextes

server/constants.go

@@ -6,11 +6,8 @@ const (
 	HeaderEthConsensusVersion = "Eth-Consensus-Version"
 	HeaderKeySlotUID          = "X-MEVBoost-SlotID"
 	HeaderKeyVersion          = "X-MEVBoost-Version"
-	// Deprecated: replaced by HeaderDateMilliseconds below.
-	HeaderStartTimeUnixMS = "X-MEVBoost-StartTimeUnixMS"
-	HeaderUserAgent       = "User-Agent"
+	HeaderUserAgent           = "User-Agent"
 	// Header which communicates when a request was sent. Used to measure latency.
-	// Replaces HeaderStartTimeUnixMS above which may be dropped in a future release.
 	HeaderDateMilliseconds = "Date-Milliseconds"
 
 	MediaTypeJSON        = "application/json"

server/get_header.go

@@ -87,7 +87,6 @@ func (m *BoostService) getHeader(log *logrus.Entry, slot phase0.Slot, pubkey, pa
 			// Add header fields to this request
 			req.Header.Set(HeaderAccept, proposerAcceptContentTypes)
 			req.Header.Set(HeaderKeySlotUID, slotUID.String())
-			req.Header.Set(HeaderStartTimeUnixMS, startTime)
 			req.Header.Set(HeaderUserAgent, userAgent)
 			req.Header.Set(HeaderDateMilliseconds, startTime)
 

server/get_payload.go

@@ -175,7 +175,6 @@ func (m *BoostService) getPayload(log *logrus.Entry, signedBlindedBeaconBlockByt
 				req.Header.Set(HeaderContentType, proposerContentType)
 				req.Header.Set(HeaderEthConsensusVersion, proposerEthConsensusVersion)
 				req.Header.Set(HeaderKeySlotUID, currentSlotUID)
-				req.Header.Set(HeaderStartTimeUnixMS, fmt.Sprintf("%d", time.Now().UTC().UnixMilli()))
 				req.Header.Set(HeaderDateMilliseconds, fmt.Sprintf("%d", time.Now().UTC().UnixMilli()))
 				req.Header.Set(HeaderUserAgent, userAgent)
 

server/service.go

@@ -228,7 +228,7 @@ func (m *BoostService) handleRegisterValidator(w http.ResponseWriter, req *http.
 	// Additional header fields
 	header := req.Header
 	header.Set(HeaderUserAgent, wrapUserAgent(ua))
-	header.Set(HeaderStartTimeUnixMS, fmt.Sprintf("%d", time.Now().UTC().UnixMilli()))
+	header.Set(HeaderDateMilliseconds, fmt.Sprintf("%d", time.Now().UTC().UnixMilli()))
 
 	// Read the validator registrations
 	regBytes, err := io.ReadAll(req.Body)