Mini SQL 2.0


W3-mSQL : Security Related Features


W3-mSQL tries to address security related issues from several points of view. The most obvious security problem is the management of access to data contained in web pages. A good solution to this problem provides both authentication of the users and access control to restrict access based on where the user is located. W3-mSQL solves this problem with an in-build authorisation scheme known as W3-auth. Because of the importance of W3-auth, we have devoted an entire manual section to it. Please see the W3-auth : Access Control and Authentication section of the manual for a full description of W3-auth and details of its operation and configuration.

When building "real" applications with a scheme such as W3-mSQL, other security related issues become apparent. Because the actual program code is embedded in the HTML code anyone wishing to obtain a copy of your source code would just need to access the W3-mSQL enhanced web page directly rather than accessing it via the W3-mSQL CGI program. If a user sis this, the source code would not be processed and would appear in the HTML sent to the browser. If a user save the source of the page from their browser they would have a full copy of your source code on their machine. Naturally, this is a major problem for people who write proprietory applications.

To overcome this problem, W3-mSQL provides 2 features, private scripts and pre-compiled libraries. Your web server may also provide a feature that can overcome this problem. All 3 options are discussed below.

Private Scripts

A problem associated with embedding your source code in an HTML document is that by pure definition an HTML document is a public document (available to anyone via your web server). The software we write with W3-mSQL is safe as long as the user only accesses it via the W3-mSQL CGI program (because it will be processed and removed from the HTML source before it is sent to the browser). So the problem is not that the source code is in the HTML file, it is that a user may access the HTML file directly by specifying the URL and bypass the W3-mSQL CGI program.

The obvious solution to this problem would be if the HTML file was not available directly from web server. If that was the case the user couldn't specify the URL directly and as such could not download your source code. But, how is this possible if the W3-mSQL expects to find the enhanced HTML file in the web document space? The solution is to install your enhanced web pages as private scripts.

A private script is an HTML file that is installed outside the web document tree (i.e. it is not directly available through your web server). When a page is requested via W3-mSQL, it looks for the file based on the URL specified. For example, if you reguested the page /cgi-bin/w3-msql/test/myfile.html, W3-mSQL would try to load and processes WEB_ROOT/test/myfile.html where WEB_ROOT is the directory in which you install web pages (such as /usr/local/etc/htdocs or similar). If it finds the file at that location is will load and process it. If it doesn't find the file at that location, W3-mSQL assumes it must be a private script.

When W3-mSQL determines that the request references a private script (i.e. it didn't find the page in the web tree) it looks in an external directory for the page. The default location for private scripts is /usr/local/Hughes/www. In the example above, W3-mSQL will try to load /usr/local/Hughes/www/test/myfile.html and process it. In short, it will use the private script directory as a second web document tree. You web server does not know that documents are stored in that directory so it is not able to send them without the help of W3-mSQL.

In the above example, if someone tried to load /test/myfile.html directly, the web server would report an error because the file does not exist in the web tree. If the user then requested it using the W3-mSQL CGI program, a check for the file in the web tree would fail so the file installed in the private script directory would be loaded, processed and sent back to the user. The elimiates the possibility of a user directly accessing your file and downloading your source code.

Lite Libraries

Lite libraries are pre-compiled version of Lite functions that are loaded into Lite scripts and W3-mSQL enhanced web pages at run-time. A complete description of Lite libraries is given in the Lite documentation so we will not reproduce it here.

From a security point of view, libraries can be used to hide your Lite source code from a user. A library is a binary version of the Lite code in the same way that an object file is a binary version of C code after it has been compiled. If all of your "sensitive" functions are placed in a library then they are totally hidden from the remote users (the binary file will be of no use to anyone as you cannot reverse the process and turn the library back into source code).

Using libraries in this way also increases the performance of your W3-mSQL applications because the source code does not need to be compiled every time the page is requested (it was compiled once and the binary version is then loaded directly into the Lite Virtual Machine when needed). Please see the section of the Lite documentation coverint libraries for further information.

HTTP Server Support

Some HTTP servers provide a mechanism via which you can map a file extension to a specific action (Apache is an example of such a web server). If your web server provides this feature you can configure it to force the processing of your W3-mSQL enhanced files automatically.

For example, let us assume that all your enhanced web pages are stored in files with a suffix of .msql (e.g. /test/myfile.msql). You could then configure your web server to process any request for a file ending in .msql through the W3-mSQL CGI program. The web server will ensure that no user can access your enhanced HTML document without it being processed by the W3-mSQL CGI program.

Configuring your web server to do this is specific to the web server you are using. For users of the Apache web server, please see the "Using W3-mSQL with Apache" document in the library section of the Hughes Technologies web site at

Copyright © 1996 Hughes Technologies Pty Ltd.