Why is FireFox hitting my server twice?

[NotionCommotion]

With only FireFox, I am getting some strange extra hit to my server soon after the first one.  It seems simlar to when the browser is looking for favicon.ico, but I have an empty file in my public root.  For troubleshooting, I added the following to my script, and have posted the results.  The culprit appears to be: [HTTP_ACCEPT] => image/png,image/*;q=0.8,*/*;q=0.5

 

What could be causing this?  Even if you don't have an exact answer, any suggestions on what to look for would be appreciated.

$old_server=isset($_SESSION['server'])?$_SESSION['server']:$_SERVER;
$difference = array_diff_assoc($_SERVER, $old_server);
$difference2 = array_diff_assoc($old_server,$_SERVER);
$_SESSION['server']=$_SERVER;
echo('$_SERVER<pre>'.print_r($_SERVER,1).'</pre>');
echo('$old_server<pre>'.print_r($old_server,1).'</pre>');
echo('$difference<pre>'.print_r($difference,1).'</pre>');
echo('$difference2<pre>'.print_r($difference2,1).'</pre>');
syslog(LOG_INFO,print_r($difference,1));

$_SERVER

Array
(
    [REDIRECT_HTTPS] => on
    [REDIRECT_SSL_TLS_SNI] => test.sites.example.com
    [REDIRECT_STATUS] => 200
    [HTTPS] => on
    [SSL_TLS_SNI] => test.sites.example.com
    [HTTP_HOST] => test.sites.example.com
    [HTTP_USER_AGENT] => Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0
    [HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    [HTTP_ACCEPT_LANGUAGE] => en-US,en;q=0.5
    [HTTP_ACCEPT_ENCODING] => gzip, deflate
    [HTTP_REFERER] => https://test.sites.example.com/administrator/index.php?cid=2&controller=sell&id=643341356
    [HTTP_COOKIE] => BACKSESSID=5il7gj9p1f3etu37l8vk8tvur1
    [HTTP_CONNECTION] => keep-alive
    [HTTP_CACHE_CONTROL] => max-age=0
    [PATH] => /sbin:/usr/sbin:/bin:/usr/bin
    [SERVER_SIGNATURE] =>
Apache/2.2.15 (CentOS) Server at test.sites.example.com Port 443


    [SERVER_SOFTWARE] => Apache/2.2.15 (CentOS)
    [SERVER_NAME] => test.sites.example.com
    [SERVER_ADDR] => 192.168.1.200
    [SERVER_PORT] => 443
    [REMOTE_ADDR] => 192.168.1.1
    [DOCUMENT_ROOT] => /var/www/example/html_sites
    [SERVER_ADMIN] => root@localhost
    [SCRIPT_FILENAME] => /var/www/example/html_sites/index.php
    [REMOTE_PORT] => 63989
    [REDIRECT_QUERY_STRING] => admin=administrator/index.php&cid=2&controller=sell&id=643341356
    [REDIRECT_URL] => /administrator/index.php
    [GATEWAY_INTERFACE] => CGI/1.1
    [SERVER_PROTOCOL] => HTTP/1.1
    [REQUEST_METHOD] => GET
    [QUERY_STRING] => admin=administrator/index.php&cid=2&controller=sell&id=643341356
    [REQUEST_URI] => /administrator/index.php?cid=2&controller=sell&id=643341356
    [SCRIPT_NAME] => /index.php
    [PHP_SELF] => /index.php
    [REQUEST_TIME_FLOAT] => 1422985053.698
    [REQUEST_TIME] => 1422985053
)

$old_server

Array
(
    [REDIRECT_HTTPS] => on
    [REDIRECT_SSL_TLS_SNI] => test.sites.example.com
    [REDIRECT_STATUS] => 200
    [HTTPS] => on
    [SSL_TLS_SNI] => test.sites.example.com
    [HTTP_HOST] => test.sites.example.com
    [HTTP_USER_AGENT] => Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0
    [HTTP_ACCEPT] => image/png,image/*;q=0.8,*/*;q=0.5
    [HTTP_ACCEPT_LANGUAGE] => en-US,en;q=0.5
    [HTTP_ACCEPT_ENCODING] => gzip, deflate
    [HTTP_REFERER] => https://test.sites.example.com/administrator/index.php?cid=2&controller=sell&id=643341356
    [HTTP_COOKIE] => BACKSESSID=5il7gj9p1f3etu37l8vk8tvur1
    [HTTP_CONNECTION] => keep-alive
    [PATH] => /sbin:/usr/sbin:/bin:/usr/bin
    [SERVER_SIGNATURE] =>
Apache/2.2.15 (CentOS) Server at test.sites.example.com Port 443


    [SERVER_SOFTWARE] => Apache/2.2.15 (CentOS)
    [SERVER_NAME] => test.sites.example.com
    [SERVER_ADDR] => 192.168.1.200
    [SERVER_PORT] => 443
    [REMOTE_ADDR] => 192.168.1.1
    [DOCUMENT_ROOT] => /var/www/example/html_sites
    [SERVER_ADMIN] => root@localhost
    [SCRIPT_FILENAME] => /var/www/example/html_sites/index.php
    [REMOTE_PORT] => 63970
    [REDIRECT_QUERY_STRING] => admin=administrator/
    [REDIRECT_URL] => /administrator/
    [GATEWAY_INTERFACE] => CGI/1.1
    [SERVER_PROTOCOL] => HTTP/1.1
    [REQUEST_METHOD] => GET
    [QUERY_STRING] => admin=administrator/
    [REQUEST_URI] => /administrator/
    [SCRIPT_NAME] => /index.php
    [PHP_SELF] => /index.php
    [REQUEST_TIME_FLOAT] => 1422985038.5
    [REQUEST_TIME] => 1422985038
)

$difference

Array
(
    [HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    [HTTP_CACHE_CONTROL] => max-age=0
    [REMOTE_PORT] => 63989
    [REDIRECT_QUERY_STRING] => admin=administrator/index.php&cid=2&controller=sell&id=643341356
    [REDIRECT_URL] => /administrator/index.php
    [QUERY_STRING] => admin=administrator/index.php&cid=2&controller=sell&id=643341356
    [REQUEST_URI] => /administrator/index.php?cid=2&controller=sell&id=643341356
    [REQUEST_TIME_FLOAT] => 1422985053.698
    [REQUEST_TIME] => 1422985053
)

$difference2

Array
(
    [HTTP_ACCEPT] => image/png,image/*;q=0.8,*/*;q=0.5
    [REMOTE_PORT] => 63970
    [REDIRECT_QUERY_STRING] => admin=administrator/
    [REDIRECT_URL] => /administrator/
    [QUERY_STRING] => admin=administrator/
    [REQUEST_URI] => /administrator/
    [REQUEST_TIME_FLOAT] => 1422985038.5
    [REQUEST_TIME] => 1422985038
)

[kicken]

You probably have an empty src attribute for an image tag.

<img src="" ...>

That is the typical cause of something like that.

[NotionCommotion]

Thanks Kicken!!!!!

 

src attribute was to be provided via ajax.  Any reason I shouldn't use src="some-file-that-does-not-exist.png"?

[scootstah]

Why would you want to display an image that doesn't exist?

 

EDIT: If you want to dynamically add an image tag from an AJAX result, then you can just add the whole image element instead of just changing the src. Or, initially set the src to a placeholder image or something.

Edited February 4, 2015 by scootstah