I get the feeling that you want help on the HTTP protocol. If you don't have (or can't use) any libraries to help, a minimal method would be to open a TCP connection and send a request message, which consists of the following: The request line and headers must all end with <CR><LF> (that is, a carriage return character followed by a line feed character). The empty line must consist of only <CR><LF> and no other whitespace. In the HTTP/1.1 protocol, all headers except Host are optional (but in practice, it's also optional if there's only one name associated with the IP address). A request line containing only the path name is accepted by servers to maintain compatibility with HTTP clients before the HTTP/1.0 specification.

You will then be able to read the response message, which consists of the following:

The Status-Line and headers must all end with <CR><LF> (a carriage return followed by a line feed). The empty line must consist of only <CR><LF> and no other whitespace.

On my computer, entering the command "telnet www.perlmonks.org 80" returns the message "Connecting To www.perlmonks.org...". If I then enter the command "GET / HTTP/1.1" and hit the <Enter> key twice, I get the following: 

HTTP/1.1 200 OK
Via: 1.1 ETC-USRPXY-02
Connection: Keep-Alive
Proxy-Connection: Keep-Alive
Content-Length: 47589
Date: Wed, 24 Jul 2013 14:08:33 GMT
Age: 74
Content-Type: text/html
ETag: "b9e5-4e24268fd6b00"
Server: Apache/2.2.24
Accept-Ranges: bytes
Last-Modified: Wed, 24 Jul 2013 14:06:04 GMT

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>

[download]
... followed by roughly 47 KB of other data. You can experiment by using telnet to connect to your server and see what you get back.

In reply to Re^3: Decode perl cgi response in C by samwyse
in thread Decode perl cgi response in C by stenasc

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