view src/http/ngx_http_special_response.c @ 4247:b79dbadb3d5e stable-1.0

Merging r4147, r4148, r4149, r4150, r4207: Fixes of combination of error_page and return directives: *) Fix for incorrect 201 replies from dav module. Replies with 201 code contain body, and we should clearly indicate it's empty if it's empty. Before 0.8.32 chunked was explicitly disabled for 201 replies and as a result empty body was indicated by connection close (not perfect, but worked). Since 0.8.32 chunked is enabled, and this causes incorrect responses from dav module when HTTP/1.1 is used: with "Transfer-Encoding: chunked" but no chunks at all. Fix is to actually return empty body in special response handler instead of abusing r->header_only flag. See here for initial report: http://mailman.nginx.org/pipermail/nginx-ru/2010-October/037535.html *) Fix for double content when return is used in error_page handler. Test case: location / { error_page 405 /nope; return 405; } location /nope { return 200; } This is expected to return 405 with empty body, but in 0.8.42+ will return builtin 405 error page as well (though not counted in Content-Length, thus breaking protocol). Fix is to use status provided by rewrite script execution in case it's less than NGX_HTTP_BAD_REQUEST even if r->error_status set. This check is in line with one in ngx_http_script_return_code(). Note that this patch also changes behaviour for "return 302 ..." and "rewrite ... redirect" used as error handler. E.g. location / { error_page 405 /redirect; return 405; } location /redirect { rewrite ^ http://example.com/; } will actually return redirect to "http://example.com/" instead of builtin 405 error page with meaningless Location header. This looks like correct change and it's in line with what happens on e.g. directory redirects in error handlers. *) Fix for "return 202" not discarding body. Big POST (not fully preread) to a location / { return 202; } resulted in incorrect behaviour due to "return" code path not calling ngx_http_discard_request_body(). The same applies to all "return" used with 2xx/3xx codes except 201 and 204, and to all "return ... text" uses. Fix is to add ngx_http_discard_request_body() call to ngx_http_send_response() function where it looks appropriate. Discard body call from emtpy gif module removed as it's now redundant. Reported by Pyry Hakulinen, see http://mailman.nginx.org/pipermail/nginx/2011-August/028503.html *) Incorrect special case for "return 204" removed. The special case in question leads to replies without body in configuration like location / { error_page 404 /zero; return 404; } location /zero { return 204; } while replies with empty body are expected per protocol specs. Correct one will look like if (status == NGX_HTTP_NO_CONTENT) { rc = ngx_http_send_header(r); if (rc == NGX_ERROR || r->header_only) { return rc; } return ngx_http_send_special(r, NGX_HTTP_LAST); } though it looks like it's better to drop this special case at all. *) Clear old Location header (if any) while adding a new one. This prevents incorrect behaviour when another redirect is issued within error_page 302 handler.
author Igor Sysoev <igor@sysoev.ru>
date Tue, 01 Nov 2011 13:45:33 +0000
parents 6afb20bf2ad5
children 4919fb357a5d
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 */


#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_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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" CRLF
"<center><h1>303 See Other</h1></center>" CRLF
;


static char ngx_http_error_400_page[] =
"<html>" CRLF
"<head><title>400 Bad Request</title></head>" CRLF
"<body bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" CRLF
"<center><h1>416 Requested Range Not Satisfiable</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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" CRLF
"<center><h1>500 Internal Server Error</h1></center>" CRLF
;


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


static char ngx_http_error_502_page[] =
"<html>" CRLF
"<head><title>502 Bad Gateway</title></head>" CRLF
"<body bgcolor=\"white\">" 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 bgcolor=\"white\">" 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 bgcolor=\"white\">" CRLF
"<center><h1>504 Gateway Time-out</h1></center>" CRLF
;


static char ngx_http_error_507_page[] =
"<html>" CRLF
"<head><title>507 Insufficient Storage</title></head>" CRLF
"<body bgcolor=\"white\">" 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_LEVEL_200  202
#define NGX_HTTP_LEVEL_200       (NGX_HTTP_LAST_LEVEL_200 - 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),

#define NGX_HTTP_LAST_LEVEL_300  304
#define NGX_HTTP_LEVEL_300       (NGX_HTTP_LAST_LEVEL_300 - 301)

    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),

#define NGX_HTTP_LAST_LEVEL_400  417
#define NGX_HTTP_LEVEL_400       (NGX_HTTP_LAST_LEVEL_400 - 400)

    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_null_string,                     /* 505 */
    ngx_null_string,                     /* 506 */
    ngx_string(ngx_http_error_507_page)

#define NGX_HTTP_LAST_LEVEL_500  508

};


static ngx_str_t  ngx_http_get_name = { 3, (u_char *) "GET " };


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: %d, \"%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:
                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) {
        error = NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    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_LEVEL_300)
    {
        /* 3XX */
        err = error - NGX_HTTP_MOVED_PERMANENTLY + NGX_HTTP_LEVEL_200;

    } else if (error >= NGX_HTTP_BAD_REQUEST
               && error < NGX_HTTP_LAST_LEVEL_400)
    {
        /* 4XX */
        err = error - NGX_HTTP_BAD_REQUEST + NGX_HTTP_LEVEL_200
                                           + NGX_HTTP_LEVEL_300;

    } else if (error >= NGX_HTTP_NGINX_CODES
               && error < NGX_HTTP_LAST_LEVEL_500)
    {
        /* 49X, 5XX */
        err = error - NGX_HTTP_NGINX_CODES + NGX_HTTP_LEVEL_200
                                           + NGX_HTTP_LEVEL_300
                                           + NGX_HTTP_LEVEL_400;
        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;
                break;
        }

    } 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.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.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_get_name;
        }

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

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

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

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

    if (overwrite >= NGX_HTTP_MOVED_PERMANENTLY
        && overwrite <= NGX_HTTP_SEE_OTHER)
    {
        r->err_status = overwrite;

    } else {
        r->err_status = NGX_HTTP_MOVED_TEMPORARILY;
    }

    location->hash = 1;
    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_LEVEL_200);
}


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) {
        len = sizeof(ngx_http_error_full_tail) - 1;
        tail = ngx_http_error_full_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_LEVEL_300)
        {
            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);

    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);

    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 = 1;
    b->last_in_chain = 1;

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

    return ngx_http_output_filter(r, &out);
}