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A common task is to log the accesses to a page. This can
be done by inserting a graphics image on a page which is only
displayed with one pixel by one pixel. The HTML sends off
to the PHP file for the graphic, which logs that it has been
called, and then returns the graphic file to the page.
Accessing a PHP log file from an HTML page: The following
script shows the code that would be inserted into the HTML.
It can be seen that the graphic file is displayed as one-pixel
by one-pixel, therefore it will be invisible to the user.
The PHP file should return the reference to the file in the
Location: field.
Logging task
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<a href ="http://myserver.co.uk/php_log.php">
<img src="http://myserver.co.uk/php_log.php"
border=0 width=1 height=1"></a>
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Executed code
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Login file: This file logs the accesses to the log file,
and then returns back the small graphics file. It also tests
the log file. If it is greater that 5000 byte, it reads it
and sends it to the owner, by email. It then erases the contents
of the file (by opening the file with the "w+" attribute.
Login file
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<?php
$str = date("F j, Y, g:i a");
$str = "<P>$str Refer: $HTTP_USER_AGENT";
$str = $str . "$REMOTE_ADDR " . gethostbyaddr($REMOTE_ADDR)
. "\n";
$filename = "logfile.htt";
$fd = fopen ($filename, "a+");
$size=filesize($filename);
$str = $str . "Size = " . $size;
$contents = fputs ($fd, $str);
if ($size>5000)
{
$headers = "Content-Type: text/html; charset=iso-8859-1\n";
fseek($fd,0);
$contents=fread($fd,filesize($filename));
mail('bill@buchananweb.co.uk',"Logfile", $contents,
$headers);
fclose($fd);
$fd = fopen ($filename, "w+");
fclose($fd);
}
else
{
fclose ($fd);
}
print "Location: http://singlepixel.gif\n\n";
?>
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Executed code
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August 28, 2001, 3:37 pm Refer: Mozilla/4.0 (compatible;
MSIE 6.0b; Windows 98; Win 9x 4.90; L1 IE5.5 December
2000)172.190.50.179 ACBE32B3.ipt.aol.com Size = 0
August 28, 2001, 3:38 pm Refer: Mozilla/4.0 (compatible;
MSIE 6.0b; Windows 98; Win 9x 4.90; L1 IE5.5 December
2000)172.190.50.179 ACBE32B3.ipt.aol.com Size = 163
August 28, 2001, 3:40 pm Refer: Mozilla/4.0 (compatible;
MSIE 6.0b; Windows 98; Win 9x 4.90; L1 IE5.5 December
2000)172.190.50.179 ACBE32B3.ipt.aol.com Size = 328
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If you have ever wondered what a 1-by-1 pixel graphic looks
like then click here.
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