Wapp

     wapptclsh examples/env.tcl

The command above should cause a web page to pop up in your web browser.
That page will look something like this:

>**Wapp Environment**
>
    BASE_URL = http://127.0.0.1:33999
    DOCUMENT_ROOT = /home/drh/wapp/examples
    HTTP_ACCEPT_ENCODING = {gzip, deflate}
    HTTP_COOKIE = {env-cookie=simple}
    HTTP_HOST = 127.0.0.1:33999
    HTTP_USER_AGENT = {Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Firefox/59.0}
    PATH_HEAD = {}
    PATH_INFO = {}
    PATH_TAIL = {}
    QUERY_STRING = {}
    REMOTE_ADDR = 127.0.0.1
    REMOTE_PORT = 53060
    REQUEST_METHOD = GET
    REQUEST_URI = /
    SAME_ORIGIN = 0
    SCRIPT_FILENAME = /home/drh/wapp/examples/env.tcl
    SCRIPT_NAME = {}
    SELF_URL = http://127.0.0.1:33999/
    env-cookie = simple
    [pwd] = /home/drh/wapp

Try this.  Then modify the URL by adding new path elements and query
parameters to see how this affects the Wapp parameters.
Notice in particular how query parameters are decoded and added to the
set of Wapp parameters.

2.0 Security By Default

These parameter look like CGI environment variables.  To prevent environment
information from overlapping and overwriting query parameters, all the
environment information uses upper-case names and all query parameters
are required to be lower case.  If an input URL contains an upper-case
query parameter (or POST parameter or cookie), that parameter is silently
omitted.

The following CGI parameters are available:

  +  **CONTENT\_LENGTH**  
     The number of bytes of POST data.
     This parameter is omitted for non-POST requests.

  +  **CONTENT\_TYPE**  
     The mimetype of the POST data.  Usually this is
     application/x-www-form-urlencoded.
     This parameter is omitted for non-POST requests.

  +  **DOCUMENT\_ROOT**  
     For CGI or SCGI, this parameter is the name a directory on the server
     that is the root of the static content tree.  When running a Wapp script
     using the built-in web server, this is the name of the directory that
     contains the script.

  +  **HTTP\_COOKIE**  
     The values of all cookies in the HTTP header.
     This parameter is omitted if there are no cookies.

  +  **HTTP\_HOST**  
     The hostname (or IP address) and port that the client used to create
     the current HTTP request.  This is the first part of the request URL,
     right after the "http://" or "https://".  The format for this value
     is "HOST:PORT".  Examples:  "sqlite.org:80" or "127.0.0.1:32172".
     Some servers omit the port number if it has a value of 80.

  +  **HTTP\_USER\_AGENT**  
     The name of the web-browser or other client program that generated
     the current HTTP request, as reported in the User-Agent header.

  +  **HTTPS**  
     If the HTTP request arrived of SSL (via "https://"), then this variable
     has the value "on".  For an unencrypted request ("http://"), this
     parameter is undefined.

  +  **PATH\_INFO**  
     The part of the URL path that follows the SCRIPT\_NAME.  For all modes
     other than CGI, this is exactly the URL pathname, though with the
     query parameters removed.  PATH_INFO begins with a "/".

  +  **REMOTE\_ADDR**  
     The IP address from which the HTTP request originated.

  +  **REMOTE\_PORT**  
     The TCP port from which teh HTTP request originated.

  +  **REQUEST\_METHOD**  
     "GET" or "HEAD" or "POST"

  +  **REQUEST\_URI**  
     The URL for the inbound request, without the initial "http://" or
     "https://" and without the HTTP\_HOST.  This variable is the same as
     the concatenation of $SCRIPT\_NAME and $PATH\_INFO.

  +  **SCRIPT\_FILENAME**  
     The full pathname on the server for the Wapp script.  This parameter
     is usually undefined for SCGI.

  +  **SCRIPT\_NAME**  
     In CGI mode, this is the name of the CGI script in the URL.  In other
     words, this is the initial part of the URL path that identifies the
     CGI script.  When using the built-in webserver, the value of this
     parameter is an empty string.  For SCGI, this parameter is normally
     undefined.


All of the above are standard CGI environment values.
The following are supplemental environment parameters are added by Wapp:


  +  **BASE\_URL**  

  +  **SELF\_URL** → "http://example.com/cgi-bin/script/method"
  +  **PATH\_HEAD** → "method"
  +  **PATH\_TAIL** → "extra/path"

The first five elements of the example above, HTTP\_HOST through
QUERY\_STRING, are standard CGI.  The final four elements are Wapp
extensions.

### 3.2 Undefined Parameters When Using SCGI on Nginx

Some of the CGI parameters are undefined by default when using CGI mode
with Nginx.  If these CGI parameters are needed by the application, then
values must be assigned in the Nginx configuration file.  For example:

>
    location /scgi/ {
       include scgi_params;
       scgi_pass localhost:9000;
       scgi_param SCRIPT_NAME "/scgi";
       scgi_param SCRIPT_FILENAME "/home/www/scgi/script1.tcl";
    }