Posts Tagged ‘Tiny’

A tiny minimalistic CHAT Client Program writen in C

Sunday, July 29th, 2012

Reading Time: < 1 minuteA friend of mine (Dido) who is learning C programming, has written a tiny chat server / client (peer to peer) program in C. His program is a very good learning curve for anyone desiring to learn basic C socket programming.
The program is writen in a way so it can be easily modified to work over UDP protocol with code:

struct sockaddr_in a;

Here are links to the code of the Chat server/client progs:

Tiny C Chat Server Client source code

Tiny C Chat Client source code

To Use the client/server compile on the server host tiny-chat-serer-client.c with:

$ cc -o tiny-chat-server tiny-chat-server.c

Then on the client host compile the client;

$ cc -o tiny-chat-client tiny-chat-client.c

On the server host tiny-chat-server should be ran with port as argument, e.g. ;

$ ./tiny-chat-server 8888

To chat with the person running tiny-chat-server the compiled server should be invoked with:

$ ./tiny-chat-client 8888 is the IP address of the host, where tiny-chat-server is executed.
The chat/server C programs are actually a primitive very raw version of talk.

The programs are in a very basic stage, there are no condition checks for incorrectly passed arguments and with wrongly passed arguments it segfaults. Still for C beginners its useful …

Tiny PHP script to dump your browser set HTTP headers (useful in debugging)

Friday, March 30th, 2012

Reading Time: 2 minutes

While browsing I stumbled upon a nice blog article

Dumping HTTP headers

The arcitle, points at few ways to DUMP the HTTP headers obtained from user browser.
As I'm not proficient with Ruby, Java and AOL Server what catched my attention is a tiny php for loop, which loops through all the HTTP_* browser set variables and prints them out. Here is the PHP script code:

<?php<br />
foreach($_SERVER as $h=>$v)<br />
if(ereg('HTTP_(.+)',$h,$hp))<br />
echo "<li>$h = $v</li>\n";<br />
header('Content-type: text/html');<br />

The script is pretty easy to use, just place it in a directory on a WebServer capable of executing php and save it under a name like:

If you don't want to bother copy pasting above code, you can also download the dump_HTTP_headers.php script here , rename the dump_HTTP_headers.php.txt to dump_HTTP_headers.php and you're ready to go.

Follow to the respective url to exec the script. I've installed the script on my webserver, so if you are curious of the output the script will be returning check your own browser HTTP set values by clicking here.
PHP will produce output like the one in the screenshot you see below, the shot is taken from my Opera browser:

Screenshot show HTTP headers.php script Opera Debian Linux

Another sample of the text output the script produce whilst invoked in my Epiphany GNOME browser is:

HTTP_USER_AGENT = Mozilla/5.0 (X11; U; Linux x86_64; en-us) AppleWebKit/531.2+ (KHTML, like Gecko) Version/5.0 Safari/531.2+ Debian/squeeze (2.30.6-1) Epiphany/2.30.6
HTTP_ACCEPT = application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
HTTP_ACCEPT_LANGUAGE = en-us, en;q=0.90
HTTP_COOKIE = __qca=P0-2141911651-1294433424320;
__utma_a2a=8614995036.1305562814.1274005888.1319809825.1320152237.2021;wooMeta=MzMxJjMyOCY1NTcmODU1MDMmMTMwODQyNDA1MDUyNCYxMzI4MjcwNjk0ODc0JiYxMDAmJjImJiYm; 3ec0a0ded7adebfeauth=22770a75911b9fb92360ec8b9cf586c9;
__utmb=238407297.1.10.1333023754; __utmc=238407297;|utmccn=(referral)|utmcmd=referral|utmcct=/blog/

You see the script returns, plenty of useful information for debugging purposes:
HTTP_HOST – Virtual Host Webserver name
HTTP_USER_AGENT – The browser exact type useragent returnedHTTP_ACCEPT – the type of MIME applications accepted by the WebServerHTTP_ACCEPT_LANGUAGE – The language types the browser has support for
HTTP_ACCEPT_ENCODING – This PHP variable is usually set to gzip or deflate by the browser if the browser has support for webserver returned content gzipping.
If HTTP_ACCEPT_ENCODING is there, then this means remote webserver is configured to return its HTML and static files in gzipped form.
HTTP_COOKIE – Information about browser cookies, this info can be used for XSS attacks etc. 🙂
HTTP_COOKIE also contains the referrar which in the above case is:|utmccn=(referral)
The Cookie information HTTP var also contains information of the exact link referrar:

For the sake of comparison show_HTTP_headers.php script output from elinks text browser is like so:

* HTTP_USER_AGENT = Links (2.3pre1; Linux 2.6.32-5-amd64 x86_64; 143x42)
* HTTP_ACCEPT_ENCODING = gzip,deflate * HTTP_ACCEPT_CHARSET = us-ascii, ISO-8859-1, ISO-8859-2, ISO-8859-3, ISO-8859-4, ISO-8859-5, ISO-8859-6, ISO-8859-7, ISO-8859-8, ISO-8859-9, ISO-8859-10, ISO-8859-13, ISO-8859-14, ISO-8859-15, ISO-8859-16, windows-1250, windows-1251, windows-1252, windows-1256,
windows-1257, cp437, cp737, cp850, cp852, cp866, x-cp866-u, x-mac, x-mac-ce, x-kam-cs, koi8-r, koi8-u, koi8-ru, TCVN-5712, VISCII,utf-8 * HTTP_ACCEPT_LANGUAGE = en,*;q=0.1
* HTTP_CONNECTION = keep-alive
One good reason, why it is good to give this script a run is cause it can help you reveal problems with HTTP headers impoperly set cookies, language encoding problems, security holes etc. Also the script is a good example, for starters in learning PHP programming.