Disabled control characters and space in header names. Control characters (0x00-0x1f, 0x7f), space, and colon were never allowed in header names. The only somewhat valid use is header continuation which nginx never supported and which is explicitly obsolete by RFC 7230. Previously, such headers were considered invalid and were ignored by default (as per ignore_invalid_headers directive). With this change, such headers are unconditionally rejected. It is expected to make nginx more resilient to various attacks, in particular, with ignore_invalid_headers switched off (which is inherently unsecure, though nevertheless sometimes used in the wild).

/*
 * 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_ */