static ngx_int_t
ngx_http_range_header_filter(ngx_http_request_t *r)
{
    time_t                        if_range_time;
    ngx_str_t                    *if_range, *etag;
    ngx_uint_t                    ranges;
    ngx_http_core_loc_conf_t     *clcf;
    ngx_http_range_filter_ctx_t  *ctx;

    if (r->http_version < NGX_HTTP_VERSION_10
        || r->headers_out.status != NGX_HTTP_OK
        || r != r->main
        || r->headers_out.content_length_n == -1
        || !r->allow_ranges)
    {
        return ngx_http_next_header_filter(r);
    }

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    if (clcf->max_ranges == 0) {
        return ngx_http_next_header_filter(r);
    }

    if (r->headers_in.range == NULL
        || r->headers_in.range->value.len < 7
        || ngx_strncasecmp(r->headers_in.range->value.data,
                           (u_char *) "bytes=", 6)
           != 0)
    {
        goto next_filter;
    }

    if (r->headers_in.if_range) {

        if_range = &r->headers_in.if_range->value;

        if (if_range->len >= 2 && if_range->data[if_range->len - 1] == '"') {

            if (r->headers_out.etag == NULL) {
                goto next_filter;
            }

            etag = &r->headers_out.etag->value;

            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "http ir:%V etag:%V", if_range, etag);

            if (if_range->len != etag->len
                || ngx_strncmp(if_range->data, etag->data, etag->len) != 0)
            {
                goto next_filter;
            }

            goto parse;
        }

        if (r->headers_out.last_modified_time == (time_t) -1) {
            goto next_filter;
        }

        if_range_time = ngx_http_parse_time(if_range->data, if_range->len);

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "http ir:%d lm:%d",
                       if_range_time, r->headers_out.last_modified_time);

        if (if_range_time != r->headers_out.last_modified_time) {
            goto next_filter;
        }
    }

parse:

    ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_range_filter_ctx_t));
    if (ctx == NULL) {
        return NGX_ERROR;
    }

    if (ngx_array_init(&ctx->ranges, r->pool, 1, sizeof(ngx_http_range_t))
        != NGX_OK)
    {
        return NGX_ERROR;
    }

    ranges = r->single_range ? 1 : clcf->max_ranges;

    switch (ngx_http_range_parse(r, ctx, ranges)) {

    case NGX_OK:
        ngx_http_set_ctx(r, ctx, ngx_http_range_body_filter_module);

        r->headers_out.status = NGX_HTTP_PARTIAL_CONTENT;
        r->headers_out.status_line.len = 0;

        if (ctx->ranges.nelts == 1) {
            return ngx_http_range_singlepart_header(r, ctx);
        }

        return ngx_http_range_multipart_header(r, ctx);

    case NGX_HTTP_RANGE_NOT_SATISFIABLE:
        return ngx_http_range_not_satisfiable(r);

    case NGX_ERROR:
        return NGX_ERROR;

    default: /* NGX_DECLINED */
        break;
    }

next_filter:

    r->headers_out.accept_ranges = ngx_list_push(&r->headers_out.headers);
    if (r->headers_out.accept_ranges == NULL) {
        return NGX_ERROR;
    }

    r->headers_out.accept_ranges->hash = 1;
    ngx_str_set(&r->headers_out.accept_ranges->key, "Accept-Ranges");
    ngx_str_set(&r->headers_out.accept_ranges->value, "bytes");

    return ngx_http_next_header_filter(r);
}
static ngx_int_t
ngx_http_range_header_filter(ngx_http_request_t *r)
{
    time_t                        if_range;
    ngx_int_t                     rc;
    ngx_http_range_filter_ctx_t  *ctx;

    if (r->http_version < NGX_HTTP_VERSION_10
        || r->headers_out.status != NGX_HTTP_OK
        || r != r->main
        || r->headers_out.content_length_n == -1
        || !r->allow_ranges)
    {
        return ngx_http_next_header_filter(r);
    }

    if (r->headers_in.range == NULL
        || r->headers_in.range->value.len < 7
        || ngx_strncasecmp(r->headers_in.range->value.data,
                           (u_char *) "bytes=", 6)
           != 0)
    {
        goto next_filter;
    }

    if (r->headers_in.if_range && r->headers_out.last_modified_time != -1) {

        if_range = ngx_http_parse_time(r->headers_in.if_range->value.data,
                                       r->headers_in.if_range->value.len);

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "http ir:%d lm:%d",
                       if_range, r->headers_out.last_modified_time);

        if (if_range != r->headers_out.last_modified_time) {
            goto next_filter;
        }
    }

    ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_range_filter_ctx_t));
    if (ctx == NULL) {
        return NGX_ERROR;
    }

    if (ngx_array_init(&ctx->ranges, r->pool, 1, sizeof(ngx_http_range_t))
        != NGX_OK)
    {
        return NGX_ERROR;
    }

    rc = ngx_http_range_parse(r, ctx);

    if (rc == NGX_OK) {

        ngx_http_set_ctx(r, ctx, ngx_http_range_body_filter_module);

        r->headers_out.status = NGX_HTTP_PARTIAL_CONTENT;
        r->headers_out.status_line.len = 0;

        if (ctx->ranges.nelts == 1) {
            return ngx_http_range_singlepart_header(r, ctx);
        }

        return ngx_http_range_multipart_header(r, ctx);
    }

    if (rc == NGX_HTTP_RANGE_NOT_SATISFIABLE) {
        return ngx_http_range_not_satisfiable(r);
    }

    /* rc == NGX_ERROR */

    return rc;

next_filter:

    r->headers_out.accept_ranges = ngx_list_push(&r->headers_out.headers);
    if (r->headers_out.accept_ranges == NULL) {
        return NGX_ERROR;
    }

    r->headers_out.accept_ranges->hash = 1;
    ngx_str_set(&r->headers_out.accept_ranges->key, "Accept-Ranges");
    ngx_str_set(&r->headers_out.accept_ranges->value, "bytes");

    return ngx_http_next_header_filter(r);
}