PHP エクステンションで nghttp2 による HPACK エンコードの例です

hpack.c

/* hpack extension for PHP */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include "php.h"
#include "ext/standard/info.h"
#include "php_hpack.h"
#include "hpack_arginfo.h"
#include <nghttp2/nghttp2.h>

/* For compatibility with older PHP versions */
#ifndef ZEND_PARSE_PARAMETERS_NONE
#define ZEND_PARSE_PARAMETERS_NONE() \
        ZEND_PARSE_PARAMETERS_START(0, 0) \
        ZEND_PARSE_PARAMETERS_END()
#endif

#define MAKE_NV(K, V)                                                          \
  {                                                                            \
    (uint8_t *)K, (uint8_t *)V, sizeof(K) - 1, sizeof(V) - 1,                  \
        NGHTTP2_NV_FLAG_NONE                                                   \
  }

/* {{{ string hpack_encode_example() */
PHP_FUNCTION(hpack_encode_example)
{
    ZEND_PARSE_PARAMETERS_NONE();

    size_t i;
    size_t nvlen;
    uint8_t *buf;
    size_t buflen;
    size_t outlen;
    int rv;
    nghttp2_hd_deflater *deflater;
    zend_string *result;

    nghttp2_nv nva[] = {
        MAKE_NV(":scheme", "https"), MAKE_NV(":authority", "example.org"),
        MAKE_NV(":path", "/"), MAKE_NV("user-agent", "libnghttp2"),
        MAKE_NV("accept-encoding", "gzip, deflate")
    };

    nvlen = sizeof(nva) / sizeof(nva[0]);

    rv = nghttp2_hd_deflate_new(&deflater, 4096);

    buflen = nghttp2_hd_deflate_bound(deflater, nva, nvlen);
    buf = malloc(buflen);
    rv = nghttp2_hd_deflate_hd(deflater, buf, buflen, nva, nvlen);
    outlen = (size_t)rv;

    result = strpprintf(outlen, "%s", buf);
    RETURN_STR(result);

    free(buf);
    nghttp2_hd_deflate_del(deflater);
}
/* }}} */

result.txt

$ php -d extension=modules/hpack.so test.php
bool(true)

test.php

<?php

var_dump(
    '8741882f91d35d055cf64d847a87a0d1d534e94d6290' === bin2hex(hpack_encode_example())
);