From 85bf354f1c19f6cfd08b8f667d069b1db29db4a4 Mon Sep 17 00:00:00 2001
From: Victor Yves Crispim <rotcivyves@hotmail.com>
Date: Thu, 7 Mar 2024 16:17:28 -0300
Subject: [PATCH] feat: validate chain id

---
 CHANGELOG.md                             | 10 ++++
 cmd/cartesi-rollups-node/chainid.go      | 73 ++++++++++++++++++++++++
 cmd/cartesi-rollups-node/chainid_test.go | 47 +++++++++++++++
 cmd/cartesi-rollups-node/main.go         |  7 +++
 4 files changed, 137 insertions(+)
 create mode 100644 cmd/cartesi-rollups-node/chainid.go
 create mode 100644 cmd/cartesi-rollups-node/chainid_test.go

diff --git a/CHANGELOG.md b/CHANGELOG.md
index beeaacfac..a1d114322 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,16 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Added
+
+- Added verification to ensure CARTESI_BLOCKCHAIN_ID matches the id returned from the Ethereum node
+
+## Changed
+
+- Changed CARTESI_BLOCKCHAIN_ID type from int to uint
+
 ## [1.3.0] 2024-02-09
 
 ### Added
diff --git a/cmd/cartesi-rollups-node/chainid.go b/cmd/cartesi-rollups-node/chainid.go
new file mode 100644
index 000000000..b44cec049
--- /dev/null
+++ b/cmd/cartesi-rollups-node/chainid.go
@@ -0,0 +1,73 @@
+// (c) Cartesi and individual authors (see AUTHORS)
+// SPDX-License-Identifier: Apache-2.0 (see LICENSE)
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/cartesi/rollups-node/internal/config"
+)
+
+// Checks if the chain id from the configuration matches the chain id reported
+// by the Ethereum node. If they don't, it returns an error.
+func validateChainId(chainId uint, ethereumNodeAddr string) error {
+	remoteChainId, err := getChainId(ethereumNodeAddr)
+	if err != nil {
+		config.ErrorLogger.Printf("Couldn't validate chainId: %v\n", err)
+	} else if chainId != remoteChainId {
+		return fmt.Errorf(
+			"chainId mismatch. Expected %v but Ethereum node returned %v",
+			chainId,
+			remoteChainId,
+		)
+	}
+	return nil
+}
+
+func getChainId(ethereumNodeAddr string) (uint, error) {
+	// create and send the request
+	requestBody := strings.NewReader(`{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":67}`)
+	resp, err := http.Post(ethereumNodeAddr, "application/json", requestBody)
+	if err != nil {
+		return 0, err
+	}
+	defer resp.Body.Close()
+
+	// parse the response body
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return 0, err
+	}
+	var chainIdResponse *GetChainIdResponse
+	err = json.Unmarshal(body, &chainIdResponse)
+	if err != nil {
+		return 0, fmt.Errorf("Failed to parse response: %v", err)
+	}
+
+	// handle the response
+	if chainIdResponse.Error != nil {
+		return 0, fmt.Errorf("Failed to get chainId: %v", chainIdResponse.Error.Message)
+	}
+	chainId, err := strconv.ParseUint(chainIdResponse.Result[2:], 16, 64)
+	if err != nil {
+		return 0, fmt.Errorf("Failed to parse chainId: %v", err)
+	}
+	return uint(chainId), nil
+}
+
+type GetChainIdResponse struct {
+	// The chainId encoded as a hex string prefixed with "0x"
+	Result string           `json:"result"`
+	Error  *GetChainIdError `json:"error"`
+}
+
+type GetChainIdError struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
diff --git a/cmd/cartesi-rollups-node/chainid_test.go b/cmd/cartesi-rollups-node/chainid_test.go
new file mode 100644
index 000000000..fbbd3c50e
--- /dev/null
+++ b/cmd/cartesi-rollups-node/chainid_test.go
@@ -0,0 +1,47 @@
+// (c) Cartesi and individual authors (see AUTHORS)
+// SPDX-License-Identifier: Apache-2.0 (see LICENSE)
+
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type ValidateChainIdSuite struct {
+	suite.Suite
+}
+
+func TestValidateChainId(t *testing.T) {
+	suite.Run(t, new(ValidateChainIdSuite))
+}
+
+func (s *ValidateChainIdSuite) TestItFailsIfChainIdsDoNotMatch() {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprintln(w, `{"jsonrpc":"2.0","id":67,"result":"0x7a69"}`)
+	}))
+	defer ts.Close()
+	localChainId := uint(11111)
+
+	err := validateChainId(localChainId, ts.URL)
+
+	s.NotNil(err)
+}
+
+func (s *ValidateChainIdSuite) TestItReturnsNilIfChainIdsMatch() {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprintln(w, `{"jsonrpc":"2.0","id":67,"result":"0x7a69"}`)
+	}))
+	defer ts.Close()
+	localChainId := uint(31337)
+
+	err := validateChainId(localChainId, ts.URL)
+
+	s.Nil(err)
+}
diff --git a/cmd/cartesi-rollups-node/main.go b/cmd/cartesi-rollups-node/main.go
index b9b7cab68..26b2d714b 100644
--- a/cmd/cartesi-rollups-node/main.go
+++ b/cmd/cartesi-rollups-node/main.go
@@ -20,6 +20,13 @@ func main() {
 	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
 	defer stop()
 
+	if err := validateChainId(
+		config.GetCartesiBlockchainId(),
+		config.GetCartesiBlockchainHttpEndpoint(),
+	); err != nil {
+		config.ErrorLogger.Fatal(err)
+	}
+
 	sunodoValidatorEnabled := config.GetCartesiExperimentalSunodoValidatorEnabled()
 	if !sunodoValidatorEnabled {
 		// add Redis first