text: #include "SchemaAllowedHandler.h"
  
  #if USE_ODBC
  
  #    include <Server/HTTP/HTMLForm.h>
  #    include <Server/HTTP/WriteBufferFromHTTPServerResponse.h>
  #    include <IO/WriteHelpers.h>
  #    include <Poco/Data/ODBC/ODBCException.h>
  #    include <Poco/Data/ODBC/SessionImpl.h>
  #    include <Poco/Data/ODBC/Utility.h>
  #    include <Poco/Net/HTTPServerRequest.h>
  #    include <Poco/Net/HTTPServerResponse.h>
  #    include <common/logger_useful.h>
  #    include "validateODBCConnectionString.h"
  
  #    define POCO_SQL_ODBC_CLASS Poco::Data::ODBC
  
  namespace DB
  {
  namespace
  {
      bool isSchemaAllowed(SQLHDBC hdbc)
      {
          SQLUINTEGER value;
          SQLSMALLINT value_length = sizeof(value);
          SQLRETURN r = POCO_SQL_ODBC_CLASS::SQLGetInfo(hdbc, SQL_SCHEMA_USAGE, &value, sizeof(value), &value_length);
  
          if (POCO_SQL_ODBC_CLASS::Utility::isError(r))
              throw POCO_SQL_ODBC_CLASS::ConnectionException(hdbc);
  
          return value != 0;
      }
  }
  
  
  void SchemaAllowedHandler::handleRequest(HTTPServerRequest & request, HTTPServerResponse & response)
  {
      HTMLForm params(request, request.getStream());
      LOG_TRACE(log, "Request URI: {}", request.getURI());
  
      auto process_error = [&response, this](const std::string & message)
      {
          response.setStatusAndReason(Poco::Net::HTTPResponse::HTTP_INTERNAL_SERVER_ERROR);
          if (!response.sent())
              *response.send() << message << std::endl;
          LOG_WARNING(log, message);
      };
  
      if (!params.has("connection_string"))
      {
          process_error("No 'connection_string' in request URL");
          return;
      }
  
      try
      {
          std::string connection_string = params.get("connection_string");
          POCO_SQL_ODBC_CLASS::SessionImpl session(validateODBCConnectionString(connection_string), DBMS_DEFAULT_CONNECT_TIMEOUT_SEC);
          SQLHDBC hdbc = session.dbc().handle();
  
          bool result = isSchemaAllowed(hdbc);
  
          WriteBufferFromHTTPServerResponse out(response, request.getMethod() == Poco::Net::HTTPRequest::HTTP_HEAD, keep_alive_timeout);
          try
          {
              writeBoolText(result, out);
              out.finalize();
          }
          catch (...)
          {
              out.finalize();
          }
      }
      catch (...)
      {
          process_error("Error getting schema usage from ODBC '" + getCurrentExceptionMessage(false) + "'");
          tryLogCurrentException(log);
      }
  }
  
  }
  
  #endif
  