Undefined index: HTTP_USER_AGENT in Sources/Subs.php on line 2848

[Speeddymon]

    * Version(s) of SMF
          o 2.0 RC3
    * Your Setup:
          o List any Modifications you have installed
          o List any Themes you have installed
                + Default theme
          o List any non-English Language packs you have installed
          o Are you using UTF-8? No
          o Any other related information? No
    * Server Software:
          o Apache/IIS version?: Apache 2.2
          o PHP version?: 5.2.6
          o Database type and version: MySQL 5.0.51a
          o Any other related server information?
    * Where the Error Occurred
          o File: Sources/Subs.php
          o Line: 2848
          o Any relevant errors in the SMF error log (if so please post them)?:
                    [11-May-2010 14:35:46] PHP Notice:  Undefined index:  HTTP_USER_AGENT in /home/uahacker/www/Sources/Subs.php on line 2848
    * How to Reproduce this Error?:
          o Unknown - Possibly from a bad spider?
    * Additional Information?
                    Site was just brought online a week ago. I assume by the error that $_SERVER['HTTP_USER_AGENT'] is null and most likely that is because of a bad spider which doesn't provide a user agent. Suspected fix would be to wrap line 2848 in an if condition that checks if HTTP_USER_AGENT is set before executing said code, and places "unknown" in both variables if it is null.

[Speeddymon]

Found these entries in my access log related to the same timestamp:

12.68.230.64 - - [11/May/2010:14:55:46 +0000] "GET /index.php?action=keepalive;time=1273589694822 HTTP/1.1" 301 20 "hxxp:android-hackers.net/themes/gallery-bootanimation.zip-install-guide-5.0.html [nonactive]" "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.1)"
12.68.230.64 - - [11/May/2010:14:55:46 +0000] "GET /index.php?action=keepalive;time=1273589694822 HTTP/1.1" 301 - "-" "-"
12.68.230.64 - - [11/May/2010:14:55:46 +0000] "GET /keepalive/time,1273589694822/ HTTP/1.1" 200 57 "hxxp:android-hackers.net/themes/gallery-bootanimation.zip-install-guide-5.0.html [nonactive]" "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.1)"

[Norv]

Sorry for the delay on this.
I didn't see this happening, but I will try to take a look. You are probably right as to the cause. (I didn't check though)

Thank you for the report!

[Joshua Dickerson]

We should really be checking this early, but the easy answer to this is    $_SESSION['USER_AGENT'] = empty($_SERVER['HTTP_USER_AGENT']) ? '' : $_SERVER['HTTP_USER_AGENT'];