Added sending of extra CONNECTION_CLOSE frames. According to quic-transport draft 28 section 10.3.1: When sending CONNECTION_CLOSE, the goal is to ensure that the peer will process the frame. Generally, this means sending the frame in a packet with the highest level of packet protection to avoid the packet being discarded. After the handshake is confirmed (see Section 4.1.2 of [QUIC-TLS]), an endpoint MUST send any CONNECTION_CLOSE frames in a 1-RTT packet. However, prior to confirming the handshake, it is possible that more advanced packet protection keys are not available to the peer, so another CONNECTION_CLOSE frame MAY be sent in a packet that uses a lower packet protection level.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#ifndef _NGX_CRC_H_INCLUDED_
#define _NGX_CRC_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


/* 32-bit crc16 */

static ngx_inline uint32_t
ngx_crc(u_char *data, size_t len)
{
    uint32_t  sum;

    for (sum = 0; len; len--) {

        /*
         * gcc 2.95.2 x86 and icc 7.1.006 compile
         * that operator into the single "rol" opcode,
         * msvc 6.0sp2 compiles it into four opcodes.
         */
        sum = sum >> 1 | sum << 31;

        sum += *data++;
    }

    return sum;
}


#endif /* _NGX_CRC_H_INCLUDED_ */