text: 
  /*
   * 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_header_filter_init(ngx_conf_t *cf);
  static ngx_int_t ngx_http_header_filter(ngx_http_request_t *r);
  
  
  static ngx_http_module_t  ngx_http_header_filter_module_ctx = {
      NULL,                                  /* preconfiguration */
      ngx_http_header_filter_init,           /* postconfiguration */
  
      NULL,                                  /* create main configuration */
      NULL,                                  /* init main configuration */
  
      NULL,                                  /* create server configuration */
      NULL,                                  /* merge server configuration */
  
      NULL,                                  /* create location configuration */
      NULL,                                  /* merge location configuration */
  };
  
  
  ngx_module_t  ngx_http_header_filter_module = {
      NGX_MODULE_V1,
      &ngx_http_header_filter_module_ctx,    /* module context */
      NULL,                                  /* module directives */
      NGX_HTTP_MODULE,                       /* module type */
      NULL,                                  /* init master */
      NULL,                                  /* init module */
      NULL,                                  /* init process */
      NULL,                                  /* init thread */
      NULL,                                  /* exit thread */
      NULL,                                  /* exit process */
      NULL,                                  /* exit master */
      NGX_MODULE_V1_PADDING
  };
  
  
  static char ngx_http_server_string[] = "Server: nginx" CRLF;
  static char ngx_http_server_full_string[] = "Server: " NGINX_VER CRLF;
  
  
  static ngx_str_t ngx_http_status_lines[] = {
  
      ngx_string("200 OK"),
      ngx_string("201 Created"),
      ngx_string("202 Accepted"),
      ngx_null_string,  /* "203 Non-Authoritative Information" */
      ngx_string("204 No Content"),
      ngx_null_string,  /* "205 Reset Content" */
      ngx_string("206 Partial Content"),
  
      /* ngx_null_string, */  /* "207 Multi-Status" */
  
  #define NGX_HTTP_LAST_2XX  207
  #define NGX_HTTP_OFF_3XX   (NGX_HTTP_LAST_2XX - 200)
  
      /* ngx_null_string, */  /* "300 Multiple Choices" */
  
      ngx_string("301 Moved Permanently"),
      ngx_string("302 Moved Temporarily"),
      ngx_string("303 See Other"),
      ngx_string("304 Not Modified"),
      ngx_null_string,  /* "305 Use Proxy" */
      ngx_null_string,  /* "306 unused" */
      ngx_string("307 Temporary Redirect"),
  
  #define NGX_HTTP_LAST_3XX  308
  #define NGX_HTTP_OFF_4XX   (NGX_HTTP_LAST_3XX - 301 + NGX_HTTP_OFF_3XX)
  
      ngx_string("400 Bad Request"),
      ngx_string("401 Unauthorized"),
      ngx_string("402 Payment Required"),
      ngx_string("403 Forbidden"),
      ngx_string("404 Not Found"),
      ngx_string("405 Not Allowed"),
      ngx_string("406 Not Acceptable"),
      ngx_null_string,  /* "407 Proxy Authentication Required" */
      ngx_string("408 Request Time-out"),
      ngx_string("409 Conflict"),
      ngx_string("410 Gone"),
      ngx_string("411 Length Required"),
      ngx_string("412 Precondition Failed"),
      ngx_string("413 Request Entity Too Large"),
      ngx_string("414 Request-URI Too Large"),
      ngx_string("415 Unsupported Media Type"),
      ngx_string("416 Requested Range Not Satisfiable"),
  
      /* ngx_null_string, */  /* "417 Expectation Failed" */
      /* ngx_null_string, */  /* "418 unused" */
      /* ngx_null_string, */  /* "419 unused" */
      /* ngx_null_string, */  /* "420 unused" */
      /* ngx_null_string, */  /* "421 unused" */
      /* ngx_null_string, */  /* "422 Unprocessable Entity" */
      /* ngx_null_string, */  /* "423 Locked" */
      /* ngx_null_string, */  /* "424 Failed Dependency" */
  
  #define NGX_HTTP_LAST_4XX  417
  #define NGX_HTTP_OFF_5XX   (NGX_HTTP_LAST_4XX - 400 + NGX_HTTP_OFF_4XX)
  
      ngx_string("500 Internal Server Error"),
      ngx_string("501 Not Implemented"),
      ngx_string("502 Bad Gateway"),
      ngx_string("503 Service Temporarily Unavailable"),
      ngx_string("504 Gateway Time-out"),
  
      ngx_null_string,        /* "505 HTTP Version Not Supported" */
      ngx_null_string,        /* "506 Variant Also Negotiates" */
      ngx_string("507 Insufficient Storage"),
      /* ngx_null_string, */  /* "508 unused" */
      /* ngx_null_string, */  /* "509 unused" */
      /* ngx_null_string, */  /* "510 Not Extended" */
  
  #define NGX_HTTP_LAST_5XX  508
  
  };
  
  
  ngx_http_header_out_t  ngx_http_headers_out[] = {
      { ngx_string("Server"), offsetof(ngx_http_headers_out_t, server) },
      { ngx_string("Date"), offsetof(ngx_http_headers_out_t, date) },
      { ngx_string("Content-Length"),
                   offsetof(ngx_http_headers_out_t, content_length) },
      { ngx_string("Content-Encoding"),
                   offsetof(ngx_http_headers_out_t, content_encoding) },
      { ngx_string("Location"), offsetof(ngx_http_headers_out_t, location) },
      { ngx_string("Last-Modified"),
                   offsetof(ngx_http_headers_out_t, last_modified) },
      { ngx_string("Accept-Ranges"),
                   offsetof(ngx_http_headers_out_t, accept_ranges) },
      { ngx_string("Expires"), offsetof(ngx_http_headers_out_t, expires) },
      { ngx_string("Cache-Control"),
                   offsetof(ngx_http_headers_out_t, cache_control) },
      { ngx_string("ETag"), offsetof(ngx_http_headers_out_t, etag) },
  
      { ngx_null_string, 0 }
  };
  
  
  static ngx_int_t
  ngx_http_header_filter(ngx_http_request_t *r)
  {
      u_char                    *p;
      size_t                     len;
      ngx_str_t                  host, *status_line;
      ngx_buf_t                 *b;
      ngx_uint_t                 status, i, port;
      ngx_chain_t                out;
      ngx_list_part_t           *part;
      ngx_table_elt_t           *header;
      ngx_connection_t          *c;
      ngx_http_core_loc_conf_t  *clcf;
      ngx_http_core_srv_conf_t  *cscf;
      struct sockaddr_in        *sin;
  #if (NGX_HAVE_INET6)
      struct sockaddr_in6       *sin6;
  #endif
      u_char                     addr[NGX_SOCKADDR_STRLEN];
  
      if (r->header_sent) {
          return NGX_OK;
      }
  
      r->header_sent = 1;
  
      if (r != r->main) {
          return NGX_OK;
      }
  
      if (r->http_version < NGX_HTTP_VERSION_10) {
          return NGX_OK;
      }
  
      if (r->method == NGX_HTTP_HEAD) {
          r->header_only = 1;
      }
  
      if (r->headers_out.last_modified_time != -1) {
          if (r->headers_out.status != NGX_HTTP_OK
              && r->headers_out.status != NGX_HTTP_PARTIAL_CONTENT
              && r->headers_out.status != NGX_HTTP_NOT_MODIFIED)
          {
              r->headers_out.last_modified_time = -1;
              r->headers_out.last_modified = NULL;
          }
      }
  
      len = sizeof("HTTP/1.x ") - 1 + sizeof(CRLF) - 1
            /* the end of the header */
            + sizeof(CRLF) - 1;
  
      /* status line */
  
      if (r->headers_out.status_line.len) {
          len += r->headers_out.status_line.len;
          status_line = &r->headers_out.status_line;
  #if (NGX_SUPPRESS_WARN)
          status = 0;
  #endif
      
  
      } else {
  
          status = r->headers_out.status;
  
          if (status >= NGX_HTTP_OK
              && status < NGX_HTTP_LAST_2XX)
          {
              /* 2XX */
  
              if (status == NGX_HTTP_NO_CONTENT) {
                  r->header_only = 1;
                  ngx_str_null(&r->headers_out.content_type);
                  r->headers_out.last_modified_time = -1;
                  r->headers_out.last_modified = NULL;
                  r->headers_out.content_length = NULL;
                  r->headers_out.content_length_n = -1;
              }
  
              status -= NGX_HTTP_OK;
              status_line = &ngx_http_status_lines[status];
              len += ngx_http_status_lines[status].len;
  
          } else if (status >= NGX_HTTP_MOVED_PERMANENTLY
                     && status < NGX_HTTP_LAST_3XX)
          {
              /* 3XX */
  
              if (status == NGX_HTTP_NOT_MODIFIED) {
                  r->header_only = 1;
              }
  
              status = status - NGX_HTTP_MOVED_PERMANENTLY + NGX_HTTP_OFF_3XX;
              status_line = &ngx_http_status_lines[status];
              len += ngx_http_status_lines[status].len;
  
          } else if (status >= NGX_HTTP_BAD_REQUEST
                     && status < NGX_HTTP_LAST_4XX)
          {
              /* 4XX */
              status = status - NGX_HTTP_BAD_REQUEST
                              + NGX_HTTP_OFF_4XX;
  
              status_line = &ngx_http_status_lines[status];
              len += ngx_http_status_lines[status].len;
  
          } else if (status >= NGX_HTTP_INTERNAL_SERVER_ERROR
                     && status < NGX_HTTP_LAST_5XX)
          {
              /* 5XX */
              status = status - NGX_HTTP_INTERNAL_SERVER_ERROR
                              + NGX_HTTP_OFF_5XX;
  
              status_line = &ngx_http_status_lines[status];
              len += ngx_http_status_lines[status].len;
  
          } else {
              printf("====%s%d===\n", r->headers_out.status_line.data, (int)r->headers_out.status);
              len += NGX_INT_T_LEN + 1 /* SP */;
              status_line = NULL;
          }
          printf("aaaaaaaaaaa\n");
  
          if (status_line && status_line->len == 0) {
              status = r->headers_out.status;
              len += NGX_INT_T_LEN + 1 /* SP */;
              status_line = NULL;
          }
      }
  
      clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
  
      if (r->headers_out.server == NULL) {
          len += clcf->server_tokens ? sizeof(ngx_http_server_full_string) - 1:
                                       sizeof(ngx_http_server_string) - 1;
      }
  
      if (r->headers_out.date == NULL) {
          len += sizeof("Date: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
      }
  
      if (r->headers_out.content_type.len) {
          len += sizeof("Content-Type: ") - 1
                 + r->headers_out.content_type.len + 2;
  
          if (r->headers_out.content_type_len == r->headers_out.content_type.len
              && r->headers_out.charset.len)
          {
              len += sizeof("; charset=") - 1 + r->headers_out.charset.len;
          }
      }
  
      if (r->headers_out.content_length == NULL
          && r->headers_out.content_length_n >= 0)
      {
          len += sizeof("Content-Length: ") - 1 + NGX_OFF_T_LEN + 2;
      }
  
      if (r->headers_out.last_modified == NULL
          && r->headers_out.last_modified_time != -1)
      {
          len += sizeof("Last-Modified: Mon, 28 Sep 1970 06:00:00 GMT" CRLF) - 1;
      }
  
      c = r->connection;
  
      if (r->headers_out.location
          && r->headers_out.location->value.len
          && r->headers_out.location->value.data[0] == '/')
      {
          r->headers_out.location->hash = 0;
  
          if (clcf->server_name_in_redirect) {
              cscf = ngx_http_get_module_srv_conf(r, ngx_http_core_module);
              host = cscf->server_name;
  
          } else if (r->headers_in.server.len) {
              host = r->headers_in.server;
  
          } else {
              host.len = NGX_SOCKADDR_STRLEN;
              host.data = addr;
  
              if (ngx_connection_local_sockaddr(c, &host, 0) != NGX_OK) {
                  return NGX_ERROR;
              }
          }
  
          switch (c->local_sockaddr->sa_family) {
  
  #if (NGX_HAVE_INET6)
          case AF_INET6:
              sin6 = (struct sockaddr_in6 *) c->local_sockaddr;
              port = ntohs(sin6->sin6_port);
              break;
  #endif
  #if (NGX_HAVE_UNIX_DOMAIN)
          case AF_UNIX:
              port = 0;
              break;
  #endif
          default: /* AF_INET */
              sin = (struct sockaddr_in *) c->local_sockaddr;
              port = ntohs(sin->sin_port);
              break;
          }
  
          len += sizeof("Location: https://") - 1
                 + host.len
                 + r->headers_out.location->value.len + 2;
  
          if (clcf->port_in_redirect) {
  
  #if (NGX_HTTP_SSL)
              if (c->ssl)
                  port = (port == 443) ? 0 : port;
              else
  #endif
                  port = (port == 80) ? 0 : port;
  
          } else {
              port = 0;
          }
  
          if (port) {
              len += sizeof(":65535") - 1;
          }
  
      } else {
          ngx_str_null(&host);
          port = 0;
      }
  
      if (r->chunked) {
          len += sizeof("Transfer-Encoding: chunked" CRLF) - 1;
      }
  
      if (r->headers_out.status == NGX_HTTP_SWITCHING_PROTOCOLS) {
          len += sizeof("Connection: upgrade" CRLF) - 1;
  
      } else if (r->keepalive) {
          len += sizeof("Connection: keep-alive" CRLF) - 1;
  
          /*
           * MSIE and Opera ignore the "Keep-Alive: timeout=<N>" header.
           * MSIE keeps the connection alive for about 60-65 seconds.
           * Opera keeps the connection alive very long.
           * Mozilla keeps the connection alive for N plus about 1-10 seconds.
           * Konqueror keeps the connection alive for about N seconds.
           */
  
          if (clcf->keepalive_header) {
              len += sizeof("Keep-Alive: timeout=") - 1 + NGX_TIME_T_LEN + 2;
          }
  
      } else {
          len += sizeof("Connection: close" CRLF) - 1;
      }
  
  #if (NGX_HTTP_GZIP)
      if (r->gzip_vary) {
          if (clcf->gzip_vary) {
              len += sizeof("Vary: Accept-Encoding" CRLF) - 1;
  
          } else {
              r->gzip_vary = 0;
          }
      }
  #endif
  
      part = &r->headers_out.headers.part;
      header = part->elts;
  
      for (i = 0; /* void */; i++) {
  
          if (i >= part->nelts) {
              if (part->next == NULL) {
                  break;
              }
  
              part = part->next;
              header = part->elts;
              i = 0;
          }
  
          if (header[i].hash == 0) {
              continue;
          }
  
          len += header[i].key.len + sizeof(": ") - 1 + header[i].value.len
                 + sizeof(CRLF) - 1;
      }
  
      b = ngx_create_temp_buf(r->pool, len);
      if (b == NULL) {
          return NGX_ERROR;
      }
  
      /* "HTTP/1.x " */
      b->last = ngx_cpymem(b->last, "HTTP/1.1 ", sizeof("HTTP/1.x ") - 1);
  
      /* status line */
      if (status_line) {
          b->last = ngx_copy(b->last, status_line->data, status_line->len);
  
      } else {
          b->last = ngx_sprintf(b->last, "%03ui ", status);
      }
      *b->last++ = CR; *b->last++ = LF;
  
      if (r->headers_out.server == NULL) {
          if (clcf->server_tokens) {
              p = (u_char *) ngx_http_server_full_string;
              len = sizeof(ngx_http_server_full_string) - 1;
  
          } else {
              p = (u_char *) ngx_http_server_string;
              len = sizeof(ngx_http_server_string) - 1;
          }
  
          b->last = ngx_cpymem(b->last, p, len);
      }
  
      if (r->headers_out.date == NULL) {
          b->last = ngx_cpymem(b->last, "Date: ", sizeof("Date: ") - 1);
          b->last = ngx_cpymem(b->last, ngx_cached_http_time.data,
                               ngx_cached_http_time.len);
  
          *b->last++ = CR; *b->last++ = LF;
      }
  
      if (r->headers_out.content_type.len) {
          b->last = ngx_cpymem(b->last, "Content-Type: ",
                               sizeof("Content-Type: ") - 1);
          p = b->last;
          b->last = ngx_copy(b->last, r->headers_out.content_type.data,
                             r->headers_out.content_type.len);
  
          if (r->headers_out.content_type_len == r->headers_out.content_type.len
              && r->headers_out.charset.len)
          {
              b->last = ngx_cpymem(b->last, "; charset=",
                                   sizeof("; charset=") - 1);
              b->last = ngx_copy(b->last, r->headers_out.charset.data,
                                 r->headers_out.charset.len);
  
              /* update r->headers_out.content_type for possible logging */
  
              r->headers_out.content_type.len = b->last - p;
              r->headers_out.content_type.data = p;
          }
  
          *b->last++ = CR; *b->last++ = LF;
      }
  
      if (r->headers_out.content_length == NULL
          && r->headers_out.content_length_n >= 0)
      {
          b->last = ngx_sprintf(b->last, "Content-Length: %O" CRLF,
                                r->headers_out.content_length_n);
      }
  
      if (r->headers_out.last_modified == NULL
          && r->headers_out.last_modified_time != -1)
      {
          b->last = ngx_cpymem(b->last, "Last-Modified: ",
                               sizeof("Last-Modified: ") - 1);
          b->last = ngx_http_time(b->last, r->headers_out.last_modified_time);
  
          *b->last++ = CR; *b->last++ = LF;
      }
  
      if (host.data) {
  
          p = b->last + sizeof("Location: ") - 1;
  
          b->last = ngx_cpymem(b->last, "Location: http",
                               sizeof("Location: http") - 1);
  
  #if (NGX_HTTP_SSL)
          if (c->ssl) {
              *b->last++ ='s';
          }
  #endif
  
          *b->last++ = ':'; *b->last++ = '/'; *b->last++ = '/';
          b->last = ngx_copy(b->last, host.data, host.len);
  
          if (port) {
              b->last = ngx_sprintf(b->last, ":%ui", port);
          }
  
          b->last = ngx_copy(b->last, r->headers_out.location->value.data,
                             r->headers_out.location->value.len);
  
          /* update r->headers_out.location->value for possible logging */
  
          r->headers_out.location->value.len = b->last - p;
          r->headers_out.location->value.data = p;
          ngx_str_set(&r->headers_out.location->key, "Location");
  
          *b->last++ = CR; *b->last++ = LF;
      }
  
      if (r->chunked) {
          b->last = ngx_cpymem(b->last, "Transfer-Encoding: chunked" CRLF,
                               sizeof("Transfer-Encoding: chunked" CRLF) - 1);
      }
  
      if (r->headers_out.status == NGX_HTTP_SWITCHING_PROTOCOLS) {
          b->last = ngx_cpymem(b->last, "Connection: upgrade" CRLF,
                               sizeof("Connection: upgrade" CRLF) - 1);
  
      } else if (r->keepalive) {
          b->last = ngx_cpymem(b->last, "Connection: keep-alive" CRLF,
                               sizeof("Connection: keep-alive" CRLF) - 1);
  
          if (clcf->keepalive_header) {
              b->last = ngx_sprintf(b->last, "Keep-Alive: timeout=%T" CRLF,
                                    clcf->keepalive_header);
          }
  
      } else {
          b->last = ngx_cpymem(b->last, "Connection: close" CRLF,
                               sizeof("Connection: close" CRLF) - 1);
      }
  
  #if (NGX_HTTP_GZIP)
      if (r->gzip_vary) {
          b->last = ngx_cpymem(b->last, "Vary: Accept-Encoding" CRLF,
                               sizeof("Vary: Accept-Encoding" CRLF) - 1);
      }
  #endif
  
      part = &r->headers_out.headers.part;
      header = part->elts;
  
      for (i = 0; /* void */; i++) {
  
          if (i >= part->nelts) {
              if (part->next == NULL) {
                  break;
              }
  
              part = part->next;
              header = part->elts;
              i = 0;
          }
  
          if (header[i].hash == 0) {
              continue;
          }
  
          b->last = ngx_copy(b->last, header[i].key.data, header[i].key.len);
          *b->last++ = ':'; *b->last++ = ' ';
  
          b->last = ngx_copy(b->last, header[i].value.data, header[i].value.len);
          *b->last++ = CR; *b->last++ = LF;
      }
  
      ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                     "%*s", (size_t) (b->last - b->pos), b->pos);
  
      /* the end of HTTP header */
      *b->last++ = CR; *b->last++ = LF;
  
      r->header_size = b->last - b->pos;
  
      if (r->header_only) {
          b->last_buf = 1;
      }
  
      out.buf = b;
      out.next = NULL;
  
      return ngx_http_write_filter(r, &out);
  }
  
  
  static ngx_int_t
  ngx_http_header_filter_init(ngx_conf_t *cf)
  {
      ngx_http_top_header_filter = ngx_http_header_filter;
  
      return NGX_OK;
  }
  