Function getChainId

src/common.cpp:70–137

Get chain ID from RPC endpoint

// Get chain ID from RPC endpoint
uint64_t getChainId(const std::string &rpc_url) {
  CURL *curl = curl_easy_init();
  if (!curl) {
    throw std::runtime_error("Failed to initialize CURL");
  }

  // Create JSON-RPC request for eth_chainId
  std::string request = R"({"jsonrpc":"2.0","id":1,"method":"eth_chainId","params":[]})";
  std::string response_string;

  curl_easy_setopt(curl, CURLOPT_URL, rpc_url.c_str());
  curl_easy_setopt(curl, CURLOPT_POSTFIELDS, request.c_str());
  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
  curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_string);
  
  // Add headers
  struct curl_slist *headers = NULL;
  headers = curl_slist_append(headers, "Content-Type: application/json");
  curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

  CURLcode res = curl_easy_perform(curl);
  curl_easy_cleanup(curl);
  curl_slist_free_all(headers);

  if (res != CURLE_OK) {
    std::cerr << "Warning: Failed to get chain ID from RPC: " 
              << curl_easy_strerror(res) << std::endl;
    return 31337; // Default to Hardhat
  }

  try {
    // Parse JSON response
    size_t json_start = response_string.find('{');
    if (json_start == std::string::npos) {
      throw std::runtime_error("Invalid JSON response");
    }
    
    std::string json_response = response_string.substr(json_start);
    
    // Simple JSON parsing for the result field
    size_t result_pos = json_response.find("\"result\"");
    if (result_pos == std::string::npos) {
      throw std::runtime_error("No result in response");
    }
    
    size_t quote_start = json_response.find("\"0x", result_pos);
    if (quote_start == std::string::npos) {
      throw std::runtime_error("Invalid chain ID format");
    }
    
    size_t quote_end = json_response.find("\"", quote_start + 1);
    if (quote_end == std::string::npos) {
      throw std::runtime_error("Invalid chain ID format");
    }
    
    std::string chain_id_hex = json_response.substr(quote_start + 1, quote_end - quote_start - 1);
    
    // Convert hex to decimal