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Rewriting FORM Tag Input

The FORM tag ACTION attribute will be rewritten by the gateway out-of-box. So, the only things to be concerned about when rewriting form data is the INPUT and SELECT tag value attributes and any JavaScript event handlers if they are being used.

There are eight INPUT types that have supporting attributes that can contain URLs, in addition to the OPTION tag value(s) that can have URLs as well. One of these INPUT types, image also has a supporting SRC attribute that will be rewritten by default out-of-the-box. Although the syntax for rewriting FORM INPUT values is different from other profile sections, the basic premise is the same. Only those values that contain URLs need to be considered. For example, it is unlikely that the value of a form INPUT TYPE of PASSWORD would ever be a URL. However, a drop-down menu used as a navigation tool could very well contain one or more URLs.

The general syntax for a rule added to the Rewrite Form INPUT Tags List section is that it contains at least three entries:

  • Page and/or object identifier

    This is the actual name of the object including any prepended path information that directly follows the protocol, web server name, and port number in the URL.

    For example, the URL http://www.iplanet.com/forms/signup.html page identifier including the path would be: /forms/signup.html

  • Form name

    This is the name of the form defined using the NAME attribute in the opening FORM tag, as in the following example:

    <FORM NAME="menuForm">
  • INPUT or OPTION tag NAME attribute

    This is the name of the INPUT or OPTION tag given using the NAME attribute, as in the following example:

    <OPTION NAME="destination1" VALUE="http://www.iplanet.com">
  • URL pattern if the right side of the value attribute assignment is not a raw URL

    The following is an example:

    <INPUT TYPE="CHECKBOX" NAME="check" VALUE="0|http://www.iplanet.com">

    These three or four fields allow for a more granular way to control how the gateway rewrites form INPUT and OPTION data. Fields can also have wildcards for more general application.

    It is usually best to be as specific as possible when generating FORM input rules so that FORM data from other pages is not unexpectedly rewritten. Consider the following example:

    <FORM>
    This is a pulldown menu:<br>
    <SELECT onChange="document.location.href=this[selectedIndex].value";>
    <OPTION VALUE="___" selected>Select Destination</OPTION>
    <OPTION VALUE="http://www.sun.com">Sun Home Page</OPTION>
    <OPTION VALUE="http://www.sun.com/solaris">Solaris Information</OPTION>
    <OPTION VALUE="http://www.iplanet.com">iPlanet Home Page</OPTION>
    </SELECT>
    </FORM>

    The FORM INPUT data can be rewritten by using the document name with its path (/forms/signup.html) in the first field of the rule, and the remaining part represented by a wildcard. A wildcard for all three initial fields can be used, making the rule look like: * * * instead of /forms/nav.html * *, or The limitations here should be obvious—the rules are too generalized.

    However, if the FORM has a name, the scope of what form data would be rewritten is narrowed substantially.

    <FORM NAME="menuForm">
    This is a pulldown menu:<br>
    <SELECT onChange="document.location.href=this[selectedIndex].value";>
    <OPTION VALUE="___" selected>Select Destination</OPTION>
    <OPTION VALUE="http://www.sun.com">Sun Home Page</OPTION>
    <OPTION VALUE="http://www.sun.com/solaris">Solaris Information</OPTION>
    <OPTION VALUE="http://www.iplanet.com">iPlanet Home Page</OPTION>
    </SELECT>
    </FORM>

    The rule can now be expressed as: /forms/nav.html menuForm * This means that only FORM INPUT data contained in a file named nav.html, at path /forms, having a FORM NAME of menuForm, will be rewritten. Because most forms have more than one field, it may be necessary to also include NAME attributes for the FORM elements so that all of the FORM contents are not blindly rewritten.

    <FORM NAME="menuForm">
    This is a pulldown menu:<br>
    <SELECT NAME="mySelect" 
    onChange="document.location.href=this[selectedIndex].value";>
    <OPTION VALUE="___" selected>Select Destination</OPTION>
    <OPTION VALUE="http://www.sun.com">Sun Home Page</OPTION>
    <OPTION VALUE="http://www.sun.com/solaris">Solaris Information</OPTION>
    <OPTION VALUE="http://www.iplanet.com">iPlanet Home Page</OPTION>
    </SELECT>
    <INPUT TYPE="HIDDEN" NAME="hidden_code" VALUE="00019283">
    <INPUT TYPE="TEXT" NAME="url_field" VALUE="Enter a URL" SIZE="20">
    <INPUT TYPE="SUBMIT" VALUE="Go!">
    </FORM>

    If the same rule is used in this case, the values for hidden_code, url_field, and even the SUBMIT button will all be rewritten.

    Instead, the rule should be amended so that it looks like: /forms/nav.html menuForm mySelect This ensures that only the URLs in the pull down menu are rewritten.

    To rewrite any other elements in the same FORM, another rule would need to be added with that particular element name in place of mySelect.

    Many FORM actions involve CGI scripts that parse the query string and evaluate the FORM data. Sometimes hidden field FORM elements are used to temporarily hold data to be sent to the CGI program and may have a mixture of data in its value that might include a URL.

    <FORM NAME="menuForm">
    This is a pulldown menu:<br>
    <SELECT NAME="mySelect" 
    onChange="document.location.href=this[selectedIndex].value";>
    <OPTION VALUE="___" selected>Select Destination</OPTION>
    <OPTION VALUE="http://www.sun.com">Sun Home Page</OPTION>
    <OPTION VALUE="http://www.sun.com/solaris">Solaris Information</OPTION>
    <OPTION VALUE="http://www.iplanet.com">iPlanet Home Page</OPTION>
    </SELECT>
    <INPUT TYPE="HIDDEN" NAME="hidden_code" 
    VALUE="00019283|http://www.iplanet.com|898239">
    <INPUT TYPE="TEXT" NAME="url_field" VALUE="Enter a URL" SIZE="20">
    <INPUT TYPE="SUBMIT" VALUE="Go!">
    </FORM>

    The only thing that has changed in this example from the previous one is that the value of the hidden INPUT field named hidden_code now has pipe-separated data values that include a URL. Rewriting the second DATA element in the value requires a URL pattern to be used in the rule syntax.

    Thus, to rewrite this particular URL, a rule will have to be added that looks like: /forms/nav.html menuForm hidden_code *|

    The *| pattern indicates to the rewriter that the raw URL will begin after the first pipe symbol in the value of the VALUE attribute. The use of non-white space separators is recommended so that rule creation is made possible.

    As an aside, you might be tempted to try and rewrite the onChange JavaScript event handler value instead of the FORM data for the drop down menu. But, the right side of the document.location.href assignment is not a raw URL, so the only way to rewrite it would be to add document.location.href to the Rewrite JavaScript Variables Function section of the gateway profile. In actuality, this will not work in Portal Server releases before SP4 Hot Patch 1 because the gateway will attempt to insert the iplanet function body inside of the SELECT tag.

Best Practices—HTML FORM Generation Programming for Use Through the Gateway

You should use the following HTML FORM generation best practices:

  • Name all FORM and FORM-related tags that contain URLs.

    This will give you better control from the rewriter as to which FORM data will need to be rewritten, as in the following example:

    <FORM NAME="myForm">
    <INPUT TYPE="HIDDEN" NAME="myURL" VALUE="http://www.iplanet.com">
    </FORM>
  • Avoid mixing contexts within the same SELECT tag.

    In other words, do not make some options URLs while others are bare strings, as in the following example:

    <SELECT NAME="mySelect"
    onChange="document.location.href=this[selectedIndex].value";>
    <OPTION VALUE="Destination1" selected>Destination1</OPTION>
    <OPTION VALUE="http://www.sun.com">Sun Home Page</OPTION>
    <OPTION VALUE="Destination2">Destination2</OPTION>
    <OPTION VALUE="http://www.iplanet.com">iPlanet Home Page</OPTION>
    </SELECT>
  • Avoid the use of white space separators in FORM data whose VALUE attribute contains multiple elements, as in the following example:

    <INPUT TYPE="HIDDEN" NAME="hidden_code" 
    VALUE="The URL is http://www.iplanet.com">
  • Avoid using generalized rules that may unintentionally rewrite other FORM data.

    For instance, you should avoid using a rule like: /index.html * *

  • Do not define FORM tag elements on multiple lines dynamically using JavaScript programming language, as in the following example:

    document.write("<INPUT TYPE=\"HIDDEN\" ");
    document.write("NAME=\"hidden_code\" ");
    document.write("VALUE=\"http://www.iplanet.com\">");
  • Avoid generating entire FORM data from within a SCRIPT element using multiple string concatenations, as in the following example:

    html+='<form name="myForm" target="myFrame";
    html+=action="http://www.iplanet.com/cgi-bin/send_form.pl" method="post">';
    html+='<input type="hidden" value="http://www.sun.com"></form>';
    • Avoid duplicate FORM element names on different pages, except when referring to a URL.

      This will reduce the number of rules required for FORM data, as in the following code snippets.

      • index.html snippet:

        <INPUT TYPE="HIDDEN" NAME="field1" VALUE="http://www.iplanet.com">
      • page2.html snippet:

        <INPUT TYPE="HIDDEN" NAME="field1" VALUE="9899898">
    • Avoid using JavaScript content to change FORM element data where a URL is a JavaScript variable, as in the following example:

      <FORM TARGET="_self"
      ACTION="http://www.sun.com/cgi-bin/gen_mail.pl?uid=$UID"
      onSubmit="this.MSG.value=top.homePageURL;">
      <INPUT TYPE="HIDDEN" NAME="MSG" VALUE="http://www.sun.com">
      </FORM>
    • Try to handle URLs in scripted buttons in the JavaScript function body if the function parameter is not a raw URL, as in the following example:

      <SCRIPT>
      function openPage(url) {
      tmpURL = url;
      }
      </SCRIPT>
      
      ...
      
      <INPUT TYPE="BUTTON" NAME="Next" VALUE="-->>Next"
      onClick="openPage(document.protocol + document.hostname + document.port + '/page2.html');">

      NOTE

      In this case, tmpURL could be added to the Rewrite JavaScript Variables Function section of the gateway profile so that the parameter is rewritten properly when the button is depressed.

    • Do not create dynamic paths for the page containing the FORM if you wish to match FORM data using the URL object as one of the specified fields in the rule name.

      The following is an example of what to avoid:

      http://www.iplanet.com/cgi-bin/forms/988923/create_form.pl

      Where part of the path itself is a random number, such as a session ID, that is used internally by the script temporarily residing in the directory.

      NOTE

      Using wildcards for the path information will not always work.

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