http2.c

  conn->send[FIRSTSOCKET] = http2_send;

  rv = (int) ((Curl_send*)httpc->send_underlying)
    (conn, FIRSTSOCKET,
     NGHTTP2_CLIENT_CONNECTION_PREFACE,
     NGHTTP2_CLIENT_CONNECTION_PREFACE_LEN,
     &rc);
  if(rc)
    /* TODO: This may get CURLE_AGAIN */
    return rc;

  if(rv != 24) {
    failf(data, "Only sent partial HTTP2 packet");
    return CURLE_SEND_ERROR;
  }

  if(conn->data->req.upgr101 == UPGR101_RECEIVED) {
    /* stream 1 is opened implicitly on upgrade */
    httpc->stream_id = 1;
    /* queue SETTINGS frame (again) */
    rv = nghttp2_session_upgrade(httpc->h2, httpc->binsettings,
                                 httpc->binlen, NULL);
    if(rv != 0) {
      failf(data, "nghttp2_session_upgrade() failed: %s(%d)",
            nghttp2_strerror(rv), rv);
      return CURLE_HTTP2;
    }
  }
  else {
    /* stream ID is unknown at this point */
    httpc->stream_id = -1;
    rv = nghttp2_submit_settings(httpc->h2, NGHTTP2_FLAG_NONE, NULL, 0);
    if(rv != 0) {
      failf(data, "nghttp2_submit_settings() failed: %s(%d)",
            nghttp2_strerror(rv), rv);
      return CURLE_HTTP2;
    }
  }
  return CURLE_OK;
}

#endif