feat: eth_sendPrivateTransaction (#182)

## 📝 Summary

This adds support for `eth_sendPrivateTransaction` instead of letting it
fall through to the provider.

## ⛱ Motivation and Context

Upstream provider is deprecating their support for this method, and adds
an extra hop.

## 📚 References

<!-- Any interesting external links to documentation, articles, tweets
which add value to the PR -->

---

## ✅ I have run these commands

* [x] `make lint`
* [x] `make test`
* [x] `go mod tidy`

Author: shanejonas

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/pkg/errors v0.9.1
 	github.com/stretchr/testify v1.9.0
 	golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa
+	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
@@ -44,8 +45,6 @@ require (
 	github.com/valyala/fastrand v1.1.0 // indirect
 	github.com/valyala/histogram v1.2.0 // indirect
 	golang.org/x/sync v0.10.0 // indirect
-	gopkg.in/yaml.v2 v2.4.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 	rsc.io/tmplfunc v0.0.3 // indirect
 )
 

openrpc.json

@@ -0,0 +1,77 @@
+{
+  "openrpc": "1.3.2",
+  "info": {
+    "title": "Protect API",
+    "description": "APIs that Protect API Serves without proxying upstream to a provider",
+    "version": "1.0.0"
+  },
+  "methods": [
+    {
+      "name": "eth_sendPrivateTransaction",
+      "description": "Send a single private transaction. Private transactions are sent directly to validators and not included in the public mempool.",
+      "params": [
+        {
+          "name": "TransactionString",
+          "description": "The raw signed transaction",
+          "required": true,
+          "schema": {
+            "type": "string"
+          }
+        },
+        {
+          "name": "MaxBlockNumber",
+          "description": "Highest block number that the block can be included in",
+          "schema": {
+            "type": "string",
+            "format": "^0x(0|[1-9a-f][0-9a-f]*)$"
+          }
+        },
+        {
+          "name": "Preferences",
+          "description": "Transaction preferences",
+          "schema": {
+            "type": "object",
+            "properties": {
+              "fast": {
+                "type": "boolean"
+              }
+            }
+          }
+        }
+      ],
+      "result": {
+        "name": "TransactionHash",
+        "schema": {
+          "title": "32 byte hex value",
+          "type": "string",
+          "pattern": "^0x[0-9a-f]{64}$"
+        }
+      },
+      "examples": [
+        {
+          "name": "sendPrivateTransactionExample",
+          "params": [
+            {
+              "name": "TransactionString",
+              "value": "0x02f87205158459682f00850c51e9727a82520894477db63b8e73aea96f201c3c4f5e8fbfcdd18b5c87038d7ea4c6800080c080a0312d6375e578ab953a41456d4be583a46dced97a9e38f349bb8e7b63d14cfc1ea001daea40332180670568a1864e6d3f910b194903128d4a0a5c499597f3f6ff40"
+            },
+            {
+              "name": "MaxBlockNumber",
+              "value": "0x2540be400"
+            },
+            {
+              "name": "Preferences",
+              "value": {
+                "fast": true
+              }
+            }
+          ],
+          "result": {
+            "name": "ResultExample",
+            "value": "0xb1770efb14906e509893b6190359658208ae64d0c56e22f748a1b0869885559e"
+          }
+        }
+      ]
+    }
+  ]
+}

server/request_handler.go

@@ -158,10 +158,10 @@ func (r *RpcRequestHandler) process() {
 // processRequest handles single request
 func (r *RpcRequestHandler) processRequest(client RPCProxyClient, jsonReq *types.JsonRpcRequest, origin, referer string, isWhitehatBundleCollection bool, whitehatBundleId string, urlParams URLParameters, reqURL string, body []byte) {
 	var entry *database.EthSendRawTxEntry
-	if jsonReq.Method == "eth_sendRawTransaction" {
+	if jsonReq.Method == "eth_sendRawTransaction" || jsonReq.Method == "eth_sendPrivateTransaction" {
 		entry = r.requestRecord.AddEthSendRawTxEntry(uuid.New())
 		// log the full url for debugging
-		r.logger.Info("[processRequest] eth_sendRawTransaction request URL", "url", reqURL)
+		r.logger.Info("[processRequest] ", jsonReq.Method, " request URL", "url", reqURL)
 	}
 	// Handle single request
 	rpcReq := NewRpcRequest(r.logger, client, jsonReq, r.relaySigningKey, r.relayUrl, origin, referer, isWhitehatBundleCollection, whitehatBundleId, entry, urlParams, r.chainID, r.rpcCache, r.defaultEthClient)

server/request_processor.go

@@ -48,6 +48,7 @@ type RpcRequest struct {
 	chainID                    []byte
 	rpcCache                   *application.RpcCache
 	flashbotsSigningAddress    string
+	maxBlockNumberOverride     uint64
 }
 
 func NewRpcRequest(
@@ -110,6 +111,9 @@ func (r *RpcRequest) ProcessRequest() *types.JsonRpcResponse {
 	case r.jsonReq.Method == "eth_sendRawTransaction":
 		r.ethSendRawTxEntry.WhiteHatBundleId = r.whitehatBundleId
 		r.handle_sendRawTransaction()
+	case r.jsonReq.Method == "eth_sendPrivateTransaction":
+		r.ethSendRawTxEntry.WhiteHatBundleId = r.whitehatBundleId
+		r.handle_sendPrivateTransaction()
 	case r.jsonReq.Method == "eth_getTransactionCount" && r.intercept_signed_eth_getTransactionCount():
 	case r.jsonReq.Method == "eth_getTransactionCount" && r.intercept_mm_eth_getTransactionCount(): // intercept if MM needs to show an error to user
 	case r.jsonReq.Method == "eth_call" && r.intercept_eth_call_to_FlashRPC_Contract(): // intercept if Flashbots isRPC contract
@@ -320,7 +324,9 @@ func (r *RpcRequest) sendTxToRelay() {
 		sendPrivateTxArgs.Preferences.Privacy.AuctionTimeout = r.urlParams.auctionTimeout
 	}
 
-	if r.urlParams.blockRange > 0 {
+	if r.maxBlockNumberOverride > 0 {
+		sendPrivateTxArgs.MaxBlockNumber = r.maxBlockNumberOverride
+	} else if r.urlParams.blockRange > 0 {
 		bn, err := r.defaultEthClient.BlockNumber(context.Background())
 		if err != nil {
 			r.logger.Error("[sendTxToRelay] BlockNumber failed", "error", err)

server/request_sendprivatetx.go

@@ -0,0 +1,37 @@
+package server
+
+import (
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/flashbots/rpc-endpoint/types"
+)
+
+func (r *RpcRequest) handle_sendPrivateTransaction() {
+	if len(r.jsonReq.Params) > 1 {
+		m, ok := r.jsonReq.Params[1].(string)
+		if !ok {
+			r.writeRpcError("MaxBlockNumber must be a string", types.JsonRpcParseError)
+			return
+		}
+		max, err := hexutil.DecodeUint64(m)
+		if err != nil {
+			r.writeRpcError("MaxBlockNumber must be a valid hexadecimal string", types.JsonRpcParseError)
+			return
+		}
+		r.maxBlockNumberOverride = max
+	}
+	if len(r.jsonReq.Params) > 2 {
+		f, ok := r.jsonReq.Params[2].(map[string]interface{})
+		if !ok {
+			r.writeRpcError("Preferences must be an object", types.JsonRpcParseError)
+			return
+		}
+		fast, ok := f["fast"].(bool)
+		if !ok {
+			r.writeRpcError("Preferences fast must be a boolean", types.JsonRpcParseError)
+			return
+		}
+		r.urlParams.pref.Fast = fast
+	}
+
+	r.handle_sendRawTransaction()
+}

tests/e2e_test.go

@@ -617,6 +617,22 @@ func TestWhitehatBundleCollectionGetBalance(t *testing.T) {
 	require.Equal(t, "0x56bc75e2d63100000", val)
 }
 
+func TestSendPrivateTransaction(t *testing.T) {
+	testServerSetupWithMockStore()
+
+	req := types.NewJsonRpcRequest(1, "eth_sendPrivateTransaction", []interface{}{
+		testutils.TestTx_BundleFailedTooManyTimes_RawTx,
+	})
+	r1 := testutils.SendRpcAndParseResponseOrFailNowAllowRpcError(t, req)
+	require.Nil(t, r1.Error)
+
+	require.Equal(t, "eth_sendPrivateTransaction", testutils.MockBackendLastJsonRpcRequest.Method)
+
+	var res string
+	json.Unmarshal(r1.Result, &res)
+	require.Equal(t, testutils.TestTx_BundleFailedTooManyTimes_Hash, res)
+}
+
 func Test_StoreRequests(t *testing.T) {
 	// Store setup
 	memStore := database.NewMemStore()