[lug] CGI Generated PDFs and MS Explorer 5.5 Problems...

[Ryan Kirkpatrick]

	Here is a problem for all you Microsoft conspiracy theorist out
there... :)

	I have a CGI program that dynamically generates PDF files and
returns them to the user's web browser for it to display. This works
without a hitch with Netscape 4.x on Linux and Windows, and with Internet
Explorer 5.0 on Windows. I simply provide the appropriate content-type
header (application/pdf), acroread is loaded, and the PDF is displayed.
	Recently though, Microsoft decided to update Internet Explorer to
version 5.5, which means many of the users of this CGI program (blindly)
followed along and upgraded. Unfortunetly the same CGI program, when it
attempts to give a user running IE 5.5 a PDF file, results in acroread
loading, followed by a blank screen and a message in the status bar that
there was an error with the file. Given Microsoft's lack of verbosity in
their error messages I did not know where to start.
	I wrote a small CGI program that just returned a static PDF file
and it too would not work with IE 5.5. I then added a Content-Length
header to better match the headers returned by Apache when a PDF file is
request directly. This appeared to solve the problem, IE 5.5 would now
display the CGI served PDF file. The perl script is below:


#!/usr/bin/perl

open(PDF,"/tmp/pdf.pdf");
$bytes = read(PDF,$pdf,5000000);
print "Content-Length: $bytes\n",
      "Content-Type: application/pdf\n\n";
print $pdf;


	Now, I attempted to change my CGI program to reflect the addition
of a Content-Lenght header. Yet, even with that additionally header IE
5.5 still refuses to show the served PDF file, and fails with the same
behavior. Lastly, I used a telnet client to connect to my server and
manually issued the HTTP commands to call the CGI program and my small
perl script above. The resulting data was identical, and the first few
lines are shown below:


HTTP/1.1 200 OK
Date: Thu, 22 Mar 2001 05:05:03 GMT
Server: Apache/1.3.9 (Unix) Debian/Alpha
Content-Length: 121727
Connection: close
Content-Type: application/pdf
Content-Language: pl

%PDF-1.2
<................Lots of Binary Data.................>


Since both CGI scripts are returning the same data, I am stumped as to why
IE 5.5 will display the PDF file from one, but not the other. The static
PDF file being served is merely a copy of one of the dynamicly generated
PDF files the CGI program is serving. In other words the PDF files being
served both CGI scripts are basically identical.
	So, anyone have any ideas on how to solve this problem, or where
to look for more clues? Also, having my users downgrade to IE5 or use
Netscape is a non-option (they are customers who's machines I have no
control over). Thanks.

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|   "For to me to live is Christ, and to die is gain."                    |
|                                            --- Philippians 1:21 (KJV)   |
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|   Ryan Kirkpatrick  |  Boulder, Colorado  |  http://www.rkirkpat.net/   |
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