text: 
  /*
   * 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 == 1) {
          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;
          r->header_only = 1;
  
      } 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;
  
      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 = -1;
      }
  
      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_OK;
      }
  
      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);
  }
  