Mercurial > hg > nginx

view src/http/ngx_http_special_response.c @ 8031:d26db4f82d7d

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
All known output headers can be linked lists now. The h->next pointer properly provided as NULL in all cases where known output headers are added. Note that there are 3rd party modules which might not do this, and it might be risky to rely on this for arbitrary headers.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 30 May 2022 21:25:45 +0300
parents ecc0ae881a25
children 697f452bc033
line wrap: on
line source


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


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


static ngx_int_t ngx_http_send_error_page(ngx_http_request_t *r,
    ngx_http_err_page_t *err_page);
static ngx_int_t ngx_http_send_special_response(ngx_http_request_t *r,
    ngx_http_core_loc_conf_t *clcf, ngx_uint_t err);
static ngx_int_t ngx_http_send_refresh(ngx_http_request_t *r);


static u_char ngx_http_error_full_tail[] =
"<hr><center>" NGINX_VER "</center>" CRLF
"</body>" CRLF
"</html>" CRLF
;


static u_char ngx_http_error_build_tail[] =
"<hr><center>" NGINX_VER_BUILD "</center>" CRLF
"</body>" CRLF
"</html>" CRLF
;


static u_char ngx_http_error_tail[] =
"<hr><center>nginx</center>" CRLF
"</body>" CRLF
"</html>" CRLF
;


static u_char ngx_http_msie_padding[] =
"<!-- a padding to disable MSIE and Chrome friendly error page -->" CRLF
"<!-- a padding to disable MSIE and Chrome friendly error page -->" CRLF
"<!-- a padding to disable MSIE and Chrome friendly error page -->" CRLF
"<!-- a padding to disable MSIE and Chrome friendly error page -->" CRLF
"<!-- a padding to disable MSIE and Chrome friendly error page -->" CRLF
"<!-- a padding to disable MSIE and Chrome friendly error page -->" CRLF
;


static u_char ngx_http_msie_refresh_head[] =
"<html><head><meta http-equiv=\"Refresh\" content=\"0; URL=";


static u_char ngx_http_msie_refresh_tail[] =
"\"></head><body></body></html>" CRLF;


static char ngx_http_error_301_page[] =
"<html>" CRLF
"<head><title>301 Moved Permanently</title></head>" CRLF
"<body>" CRLF
"<center><h1>301 Moved Permanently</h1></center>" CRLF
;


static char ngx_http_error_302_page[] =
"<html>" CRLF
"<head><title>302 Found</title></head>" CRLF
"<body>" CRLF
"<center><h1>302 Found</h1></center>" CRLF
;


static char ngx_http_error_303_page[] =
"<html>" CRLF
"<head><title>303 See Other</title></head>" CRLF
"<body>" CRLF
"<center><h1>303 See Other</h1></center>" CRLF
;


static char ngx_http_error_307_page[] =
"<html>" CRLF
"<head><title>307 Temporary Redirect</title></head>" CRLF
"<body>" CRLF
"<center><h1>307 Temporary Redirect</h1></center>" CRLF
;


static char ngx_http_error_308_page[] =
"<html>" CRLF
"<head><title>308 Permanent Redirect</title></head>" CRLF
"<body>" CRLF
"<center><h1>308 Permanent Redirect</h1></center>" CRLF
;


static char ngx_http_error_400_page[] =
"<html>" CRLF
"<head><title>400 Bad Request</title></head>" CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
;


static char ngx_http_error_401_page[] =
"<html>" CRLF
"<head><title>401 Authorization Required</title></head>" CRLF
"<body>" CRLF
"<center><h1>401 Authorization Required</h1></center>" CRLF
;


static char ngx_http_error_402_page[] =
"<html>" CRLF
"<head><title>402 Payment Required</title></head>" CRLF
"<body>" CRLF
"<center><h1>402 Payment Required</h1></center>" CRLF
;


static char ngx_http_error_403_page[] =
"<html>" CRLF
"<head><title>403 Forbidden</title></head>" CRLF
"<body>" CRLF
"<center><h1>403 Forbidden</h1></center>" CRLF
;


static char ngx_http_error_404_page[] =
"<html>" CRLF
"<head><title>404 Not Found</title></head>" CRLF
"<body>" CRLF
"<center><h1>404 Not Found</h1></center>" CRLF
;


static char ngx_http_error_405_page[] =
"<html>" CRLF
"<head><title>405 Not Allowed</title></head>" CRLF
"<body>" CRLF
"<center><h1>405 Not Allowed</h1></center>" CRLF
;


static char ngx_http_error_406_page[] =
"<html>" CRLF
"<head><title>406 Not Acceptable</title></head>" CRLF
"<body>" CRLF
"<center><h1>406 Not Acceptable</h1></center>" CRLF
;


static char ngx_http_error_408_page[] =
"<html>" CRLF
"<head><title>408 Request Time-out</title></head>" CRLF
"<body>" CRLF
"<center><h1>408 Request Time-out</h1></center>" CRLF
;


static char ngx_http_error_409_page[] =
"<html>" CRLF
"<head><title>409 Conflict</title></head>" CRLF
"<body>" CRLF
"<center><h1>409 Conflict</h1></center>" CRLF
;


static char ngx_http_error_410_page[] =
"<html>" CRLF
"<head><title>410 Gone</title></head>" CRLF
"<body>" CRLF
"<center><h1>410 Gone</h1></center>" CRLF
;


static char ngx_http_error_411_page[] =
"<html>" CRLF
"<head><title>411 Length Required</title></head>" CRLF
"<body>" CRLF
"<center><h1>411 Length Required</h1></center>" CRLF
;


static char ngx_http_error_412_page[] =
"<html>" CRLF
"<head><title>412 Precondition Failed</title></head>" CRLF
"<body>" CRLF
"<center><h1>412 Precondition Failed</h1></center>" CRLF
;


static char ngx_http_error_413_page[] =
"<html>" CRLF
"<head><title>413 Request Entity Too Large</title></head>" CRLF
"<body>" CRLF
"<center><h1>413 Request Entity Too Large</h1></center>" CRLF
;


static char ngx_http_error_414_page[] =
"<html>" CRLF
"<head><title>414 Request-URI Too Large</title></head>" CRLF
"<body>" CRLF
"<center><h1>414 Request-URI Too Large</h1></center>" CRLF
;


static char ngx_http_error_415_page[] =
"<html>" CRLF
"<head><title>415 Unsupported Media Type</title></head>" CRLF
"<body>" CRLF
"<center><h1>415 Unsupported Media Type</h1></center>" CRLF
;


static char ngx_http_error_416_page[] =
"<html>" CRLF
"<head><title>416 Requested Range Not Satisfiable</title></head>" CRLF
"<body>" CRLF
"<center><h1>416 Requested Range Not Satisfiable</h1></center>" CRLF
;


static char ngx_http_error_421_page[] =
"<html>" CRLF
"<head><title>421 Misdirected Request</title></head>" CRLF
"<body>" CRLF
"<center><h1>421 Misdirected Request</h1></center>" CRLF
;


static char ngx_http_error_429_page[] =
"<html>" CRLF
"<head><title>429 Too Many Requests</title></head>" CRLF
"<body>" CRLF
"<center><h1>429 Too Many Requests</h1></center>" CRLF
;


static char ngx_http_error_494_page[] =
"<html>" CRLF
"<head><title>400 Request Header Or Cookie Too Large</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>Request Header Or Cookie Too Large</center>" CRLF
;


static char ngx_http_error_495_page[] =
"<html>" CRLF
"<head><title>400 The SSL certificate error</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>The SSL certificate error</center>" CRLF
;


static char ngx_http_error_496_page[] =
"<html>" CRLF
"<head><title>400 No required SSL certificate was sent</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>No required SSL certificate was sent</center>" CRLF
;


static char ngx_http_error_497_page[] =
"<html>" CRLF
"<head><title>400 The plain HTTP request was sent to HTTPS port</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>The plain HTTP request was sent to HTTPS port</center>" CRLF
;


static char ngx_http_error_500_page[] =
"<html>" CRLF
"<head><title>500 Internal Server Error</title></head>" CRLF
"<body>" CRLF
"<center><h1>500 Internal Server Error</h1></center>" CRLF
;


static char ngx_http_error_501_page[] =
"<html>" CRLF
"<head><title>501 Not Implemented</title></head>" CRLF
"<body>" CRLF
"<center><h1>501 Not Implemented</h1></center>" CRLF
;


static char ngx_http_error_502_page[] =
"<html>" CRLF
"<head><title>502 Bad Gateway</title></head>" CRLF
"<body>" CRLF
"<center><h1>502 Bad Gateway</h1></center>" CRLF
;


static char ngx_http_error_503_page[] =
"<html>" CRLF
"<head><title>503 Service Temporarily Unavailable</title></head>" CRLF
"<body>" CRLF
"<center><h1>503 Service Temporarily Unavailable</h1></center>" CRLF
;


static char ngx_http_error_504_page[] =
"<html>" CRLF
"<head><title>504 Gateway Time-out</title></head>" CRLF
"<body>" CRLF
"<center><h1>504 Gateway Time-out</h1></center>" CRLF
;


static char ngx_http_error_505_page[] =
"<html>" CRLF
"<head><title>505 HTTP Version Not Supported</title></head>" CRLF
"<body>" CRLF
"<center><h1>505 HTTP Version Not Supported</h1></center>" CRLF
;


static char ngx_http_error_507_page[] =
"<html>" CRLF
"<head><title>507 Insufficient Storage</title></head>" CRLF
"<body>" CRLF
"<center><h1>507 Insufficient Storage</h1></center>" CRLF
;


static ngx_str_t ngx_http_error_pages[] = {

    ngx_null_string,                     /* 201, 204 */

#define NGX_HTTP_LAST_2XX  202
#define NGX_HTTP_OFF_3XX   (NGX_HTTP_LAST_2XX - 201)

    /* ngx_null_string, */               /* 300 */
    ngx_string(ngx_http_error_301_page),
    ngx_string(ngx_http_error_302_page),
    ngx_string(ngx_http_error_303_page),
    ngx_null_string,                     /* 304 */
    ngx_null_string,                     /* 305 */
    ngx_null_string,                     /* 306 */
    ngx_string(ngx_http_error_307_page),
    ngx_string(ngx_http_error_308_page),

#define NGX_HTTP_LAST_3XX  309
#define NGX_HTTP_OFF_4XX   (NGX_HTTP_LAST_3XX - 301 + NGX_HTTP_OFF_3XX)

    ngx_string(ngx_http_error_400_page),
    ngx_string(ngx_http_error_401_page),
    ngx_string(ngx_http_error_402_page),
    ngx_string(ngx_http_error_403_page),
    ngx_string(ngx_http_error_404_page),
    ngx_string(ngx_http_error_405_page),
    ngx_string(ngx_http_error_406_page),
    ngx_null_string,                     /* 407 */
    ngx_string(ngx_http_error_408_page),
    ngx_string(ngx_http_error_409_page),
    ngx_string(ngx_http_error_410_page),
    ngx_string(ngx_http_error_411_page),
    ngx_string(ngx_http_error_412_page),
    ngx_string(ngx_http_error_413_page),
    ngx_string(ngx_http_error_414_page),
    ngx_string(ngx_http_error_415_page),
    ngx_string(ngx_http_error_416_page),
    ngx_null_string,                     /* 417 */
    ngx_null_string,                     /* 418 */
    ngx_null_string,                     /* 419 */
    ngx_null_string,                     /* 420 */
    ngx_string(ngx_http_error_421_page),
    ngx_null_string,                     /* 422 */
    ngx_null_string,                     /* 423 */
    ngx_null_string,                     /* 424 */
    ngx_null_string,                     /* 425 */
    ngx_null_string,                     /* 426 */
    ngx_null_string,                     /* 427 */
    ngx_null_string,                     /* 428 */
    ngx_string(ngx_http_error_429_page),

#define NGX_HTTP_LAST_4XX  430
#define NGX_HTTP_OFF_5XX   (NGX_HTTP_LAST_4XX - 400 + NGX_HTTP_OFF_4XX)

    ngx_string(ngx_http_error_494_page), /* 494, request header too large */
    ngx_string(ngx_http_error_495_page), /* 495, https certificate error */
    ngx_string(ngx_http_error_496_page), /* 496, https no certificate */
    ngx_string(ngx_http_error_497_page), /* 497, http to https */
    ngx_string(ngx_http_error_404_page), /* 498, canceled */
    ngx_null_string,                     /* 499, client has closed connection */

    ngx_string(ngx_http_error_500_page),
    ngx_string(ngx_http_error_501_page),
    ngx_string(ngx_http_error_502_page),
    ngx_string(ngx_http_error_503_page),
    ngx_string(ngx_http_error_504_page),
    ngx_string(ngx_http_error_505_page),
    ngx_null_string,                     /* 506 */
    ngx_string(ngx_http_error_507_page)

#define NGX_HTTP_LAST_5XX  508

};


ngx_int_t
ngx_http_special_response_handler(ngx_http_request_t *r, ngx_int_t error)
{
    ngx_uint_t                 i, err;
    ngx_http_err_page_t       *err_page;
    ngx_http_core_loc_conf_t  *clcf;

    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http special response: %i, \"%V?%V\"",
                   error, &r->uri, &r->args);

    r->err_status = error;

    if (r->keepalive) {
        switch (error) {
            case NGX_HTTP_BAD_REQUEST:
            case NGX_HTTP_REQUEST_ENTITY_TOO_LARGE:
            case NGX_HTTP_REQUEST_URI_TOO_LARGE:
            case NGX_HTTP_TO_HTTPS:
            case NGX_HTTPS_CERT_ERROR:
            case NGX_HTTPS_NO_CERT:
            case NGX_HTTP_INTERNAL_SERVER_ERROR:
            case NGX_HTTP_NOT_IMPLEMENTED:
                r->keepalive = 0;
        }
    }

    if (r->lingering_close) {
        switch (error) {
            case NGX_HTTP_BAD_REQUEST:
            case NGX_HTTP_TO_HTTPS:
            case NGX_HTTPS_CERT_ERROR:
            case NGX_HTTPS_NO_CERT:
                r->lingering_close = 0;
        }
    }

    r->headers_out.content_type.len = 0;

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    if (!r->error_page && clcf->error_pages && r->uri_changes != 0) {

        if (clcf->recursive_error_pages == 0) {
            r->error_page = 1;
        }

        err_page = clcf->error_pages->elts;

        for (i = 0; i < clcf->error_pages->nelts; i++) {
            if (err_page[i].status == error) {
                return ngx_http_send_error_page(r, &err_page[i]);
            }
        }
    }

    r->expect_tested = 1;

    if (ngx_http_discard_request_body(r) != NGX_OK) {
        r->keepalive = 0;
    }

    if (clcf->msie_refresh
        && r->headers_in.msie
        && (error == NGX_HTTP_MOVED_PERMANENTLY
            || error == NGX_HTTP_MOVED_TEMPORARILY))
    {
        return ngx_http_send_refresh(r);
    }

    if (error == NGX_HTTP_CREATED) {
        /* 201 */
        err = 0;

    } else if (error == NGX_HTTP_NO_CONTENT) {
        /* 204 */
        err = 0;

    } else if (error >= NGX_HTTP_MOVED_PERMANENTLY
               && error < NGX_HTTP_LAST_3XX)
    {
        /* 3XX */
        err = error - NGX_HTTP_MOVED_PERMANENTLY + NGX_HTTP_OFF_3XX;

    } else if (error >= NGX_HTTP_BAD_REQUEST
               && error < NGX_HTTP_LAST_4XX)
    {
        /* 4XX */
        err = error - NGX_HTTP_BAD_REQUEST + NGX_HTTP_OFF_4XX;

    } else if (error >= NGX_HTTP_NGINX_CODES
               && error < NGX_HTTP_LAST_5XX)
    {
        /* 49X, 5XX */
        err = error - NGX_HTTP_NGINX_CODES + NGX_HTTP_OFF_5XX;
        switch (error) {
            case NGX_HTTP_TO_HTTPS:
            case NGX_HTTPS_CERT_ERROR:
            case NGX_HTTPS_NO_CERT:
            case NGX_HTTP_REQUEST_HEADER_TOO_LARGE:
                r->err_status = NGX_HTTP_BAD_REQUEST;
        }

    } else {
        /* unknown code, zero body */
        err = 0;
    }

    return ngx_http_send_special_response(r, clcf, err);
}


ngx_int_t
ngx_http_filter_finalize_request(ngx_http_request_t *r, ngx_module_t *m,
    ngx_int_t error)
{
    void       *ctx;
    ngx_int_t   rc;

    ngx_http_clean_header(r);

    ctx = NULL;

    if (m) {
        ctx = r->ctx[m->ctx_index];
    }

    /* clear the modules contexts */
    ngx_memzero(r->ctx, sizeof(void *) * ngx_http_max_module);

    if (m) {
        r->ctx[m->ctx_index] = ctx;
    }

    r->filter_finalize = 1;

    rc = ngx_http_special_response_handler(r, error);

    /* NGX_ERROR resets any pending data */

    switch (rc) {

    case NGX_OK:
    case NGX_DONE:
        return NGX_ERROR;

    default:
        return rc;
    }
}


void
ngx_http_clean_header(ngx_http_request_t *r)
{
    ngx_memzero(&r->headers_out.status,
                sizeof(ngx_http_headers_out_t)
                    - offsetof(ngx_http_headers_out_t, status));

    r->headers_out.headers.part.nelts = 0;
    r->headers_out.headers.part.next = NULL;
    r->headers_out.headers.last = &r->headers_out.headers.part;

    r->headers_out.trailers.part.nelts = 0;
    r->headers_out.trailers.part.next = NULL;
    r->headers_out.trailers.last = &r->headers_out.trailers.part;

    r->headers_out.content_length_n = -1;
    r->headers_out.last_modified_time = -1;
}


static ngx_int_t
ngx_http_send_error_page(ngx_http_request_t *r, ngx_http_err_page_t *err_page)
{
    ngx_int_t                  overwrite;
    ngx_str_t                  uri, args;
    ngx_table_elt_t           *location;
    ngx_http_core_loc_conf_t  *clcf;

    overwrite = err_page->overwrite;

    if (overwrite && overwrite != NGX_HTTP_OK) {
        r->expect_tested = 1;
    }

    if (overwrite >= 0) {
        r->err_status = overwrite;
    }

    if (ngx_http_complex_value(r, &err_page->value, &uri) != NGX_OK) {
        return NGX_ERROR;
    }

    if (uri.len && uri.data[0] == '/') {

        if (err_page->value.lengths) {
            ngx_http_split_args(r, &uri, &args);

        } else {
            args = err_page->args;
        }

        if (r->method != NGX_HTTP_HEAD) {
            r->method = NGX_HTTP_GET;
            r->method_name = ngx_http_core_get_method;
        }

        return ngx_http_internal_redirect(r, &uri, &args);
    }

    if (uri.len && uri.data[0] == '@') {
        return ngx_http_named_location(r, &uri);
    }

    r->expect_tested = 1;

    if (ngx_http_discard_request_body(r) != NGX_OK) {
        r->keepalive = 0;
    }

    location = ngx_list_push(&r->headers_out.headers);

    if (location == NULL) {
        return NGX_ERROR;
    }

    if (overwrite != NGX_HTTP_MOVED_PERMANENTLY
        && overwrite != NGX_HTTP_MOVED_TEMPORARILY
        && overwrite != NGX_HTTP_SEE_OTHER
        && overwrite != NGX_HTTP_TEMPORARY_REDIRECT
        && overwrite != NGX_HTTP_PERMANENT_REDIRECT)
    {
        r->err_status = NGX_HTTP_MOVED_TEMPORARILY;
    }

    location->hash = 1;
    location->next = NULL;
    ngx_str_set(&location->key, "Location");
    location->value = uri;

    ngx_http_clear_location(r);

    r->headers_out.location = location;

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    if (clcf->msie_refresh && r->headers_in.msie) {
        return ngx_http_send_refresh(r);
    }

    return ngx_http_send_special_response(r, clcf, r->err_status
                                                   - NGX_HTTP_MOVED_PERMANENTLY
                                                   + NGX_HTTP_OFF_3XX);
}


static ngx_int_t
ngx_http_send_special_response(ngx_http_request_t *r,
    ngx_http_core_loc_conf_t *clcf, ngx_uint_t err)
{
    u_char       *tail;
    size_t        len;
    ngx_int_t     rc;
    ngx_buf_t    *b;
    ngx_uint_t    msie_padding;
    ngx_chain_t   out[3];

    if (clcf->server_tokens == NGX_HTTP_SERVER_TOKENS_ON) {
        len = sizeof(ngx_http_error_full_tail) - 1;
        tail = ngx_http_error_full_tail;

    } else if (clcf->server_tokens == NGX_HTTP_SERVER_TOKENS_BUILD) {
        len = sizeof(ngx_http_error_build_tail) - 1;
        tail = ngx_http_error_build_tail;

    } else {
        len = sizeof(ngx_http_error_tail) - 1;
        tail = ngx_http_error_tail;
    }

    msie_padding = 0;

    if (ngx_http_error_pages[err].len) {
        r->headers_out.content_length_n = ngx_http_error_pages[err].len + len;
        if (clcf->msie_padding
            && (r->headers_in.msie || r->headers_in.chrome)
            && r->http_version >= NGX_HTTP_VERSION_10
            && err >= NGX_HTTP_OFF_4XX)
        {
            r->headers_out.content_length_n +=
                                         sizeof(ngx_http_msie_padding) - 1;
            msie_padding = 1;
        }

        r->headers_out.content_type_len = sizeof("text/html") - 1;
        ngx_str_set(&r->headers_out.content_type, "text/html");
        r->headers_out.content_type_lowcase = NULL;

    } else {
        r->headers_out.content_length_n = 0;
    }

    if (r->headers_out.content_length) {
        r->headers_out.content_length->hash = 0;
        r->headers_out.content_length = NULL;
    }

    ngx_http_clear_accept_ranges(r);
    ngx_http_clear_last_modified(r);
    ngx_http_clear_etag(r);

    rc = ngx_http_send_header(r);

    if (rc == NGX_ERROR || r->header_only) {
        return rc;
    }

    if (ngx_http_error_pages[err].len == 0) {
        return ngx_http_send_special(r, NGX_HTTP_LAST);
    }

    b = ngx_calloc_buf(r->pool);
    if (b == NULL) {
        return NGX_ERROR;
    }

    b->memory = 1;
    b->pos = ngx_http_error_pages[err].data;
    b->last = ngx_http_error_pages[err].data + ngx_http_error_pages[err].len;

    out[0].buf = b;
    out[0].next = &out[1];

    b = ngx_calloc_buf(r->pool);
    if (b == NULL) {
        return NGX_ERROR;
    }

    b->memory = 1;

    b->pos = tail;
    b->last = tail + len;

    out[1].buf = b;
    out[1].next = NULL;

    if (msie_padding) {
        b = ngx_calloc_buf(r->pool);
        if (b == NULL) {
            return NGX_ERROR;
        }

        b->memory = 1;
        b->pos = ngx_http_msie_padding;
        b->last = ngx_http_msie_padding + sizeof(ngx_http_msie_padding) - 1;

        out[1].next = &out[2];
        out[2].buf = b;
        out[2].next = NULL;
    }

    if (r == r->main) {
        b->last_buf = 1;
    }

    b->last_in_chain = 1;

    return ngx_http_output_filter(r, &out[0]);
}


static ngx_int_t
ngx_http_send_refresh(ngx_http_request_t *r)
{
    u_char       *p, *location;
    size_t        len, size;
    uintptr_t     escape;
    ngx_int_t     rc;
    ngx_buf_t    *b;
    ngx_chain_t   out;

    len = r->headers_out.location->value.len;
    location = r->headers_out.location->value.data;

    escape = 2 * ngx_escape_uri(NULL, location, len, NGX_ESCAPE_REFRESH);

    size = sizeof(ngx_http_msie_refresh_head) - 1
           + escape + len
           + sizeof(ngx_http_msie_refresh_tail) - 1;

    r->err_status = NGX_HTTP_OK;

    r->headers_out.content_type_len = sizeof("text/html") - 1;
    ngx_str_set(&r->headers_out.content_type, "text/html");
    r->headers_out.content_type_lowcase = NULL;

    r->headers_out.location->hash = 0;
    r->headers_out.location = NULL;

    r->headers_out.content_length_n = size;

    if (r->headers_out.content_length) {
        r->headers_out.content_length->hash = 0;
        r->headers_out.content_length = NULL;
    }

    ngx_http_clear_accept_ranges(r);
    ngx_http_clear_last_modified(r);
    ngx_http_clear_etag(r);

    rc = ngx_http_send_header(r);

    if (rc == NGX_ERROR || r->header_only) {
        return rc;
    }

    b = ngx_create_temp_buf(r->pool, size);
    if (b == NULL) {
        return NGX_ERROR;
    }

    p = ngx_cpymem(b->pos, ngx_http_msie_refresh_head,
                   sizeof(ngx_http_msie_refresh_head) - 1);

    if (escape == 0) {
        p = ngx_cpymem(p, location, len);

    } else {
        p = (u_char *) ngx_escape_uri(p, location, len, NGX_ESCAPE_REFRESH);
    }

    b->last = ngx_cpymem(p, ngx_http_msie_refresh_tail,
                         sizeof(ngx_http_msie_refresh_tail) - 1);

    b->last_buf = (r == r->main) ? 1 : 0;
    b->last_in_chain = 1;

    out.buf = b;
    out.next = NULL;

    return ngx_http_output_filter(r, &out);
}