feat(handlers): postShared returns 429 when disperser rate limited cl…

…ient

server/errors.go

@@ -6,6 +6,8 @@ import (
 
 	"github.com/Layr-Labs/eigenda-proxy/commitments"
 	"github.com/Layr-Labs/eigenda-proxy/store"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 // MetaError includes both an error and commitment metadata
@@ -35,3 +37,10 @@ func is400(err error) bool {
 	// for the 400s returned by the disperser server (currently only INVALID_ARGUMENT).
 	return errors.Is(err, store.ErrProxyOversizedBlob)
 }
+
+func is429(err error) bool {
+	// grpc RESOURCE_EXHAUSTED is returned by the disperser server when the client has sent too many requests
+	// in a short period of time. This is a client-side issue, so we should return the 429 to the client.
+	st, isGRPCError := status.FromError(err)
+	return isGRPCError && st.Code() == codes.ResourceExhausted
+}

server/handlers.go

@@ -183,6 +183,8 @@ func (svr *Server) handlePostShared(w http.ResponseWriter, r *http.Request, comm
 		switch {
 		case is400(err):
 			http.Error(w, err.Error(), http.StatusBadRequest)
+		case is429(err):
+			http.Error(w, err.Error(), http.StatusTooManyRequests)
 		case errors.Is(err, &api.ErrorFailover{}):
 			// this tells the caller (batcher) to failover to ethda b/c eigenda is temporarily down
 			http.Error(w, err.Error(), http.StatusServiceUnavailable)