url.c

          /* We have connected or sent away a name resolve query fine */

          conn = *connp; /* setup conn to again point to something nice */
          if(async) {
            /* Now, if async is TRUE here, we need to wait for the name
               to resolve */
            result = Curl_wait_for_resolv(conn, NULL);
            if(result)
              return result;

            /* Resolved, continue with the connection */
            result = Curl_async_resolved(conn, &protocol_done);
            if(result)
              return result;
          }

          /* ... finally back to actually retry the DO phase */
          result = conn->handler->do_it(conn, done);
        }
      }
    }

    if((result == CURLE_OK) && *done)
      /* do_complete must be called after the protocol-specific DO function */
      do_complete(conn);
  }
  return result;
}

CURLcode Curl_do_more(struct connectdata *conn)
{
  CURLcode result=CURLE_OK;

  if(conn->handler->do_more)
    result = conn->handler->do_more(conn);

  if(result == CURLE_OK)
    /* do_complete must be called after the protocol-specific DO function */
    do_complete(conn);

  return result;
}

/* Called on connect, and if there's already a protocol-specific struct
   allocated for a different connection, this frees it that it can be setup
   properly later on. */
void Curl_reset_reqproto(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;
  if(data->state.proto.generic && data->state.current_conn != conn) {
    free(data->state.proto.generic);
    data->state.proto.generic = NULL;
  }
  data->state.current_conn = conn;
}