PHP socket programming using the Fsockopen () function

A socket can be understood as a channel in which two computers communicate with one Another.

Usage: Use the Fsockopen () function

See the previous article for specific usage. The parameters for the function are url, port number, A variable that holds the error number, a variable that holds the error message string, and a timeout wait Time. (only The first parameter is Required)

Common Port Tables:

Port number	Main purpose
21st	Ftp
22	Ssh
23	Telnet
25	Smtp
80	Web
110	POP

Where several parts of the URL are: protocol name (scheme), host, port number (port), file path (path), and query Parameters.

When the URL is http://www.example.com/view.php?week=1#demo:

Index	Value
Scheme	http
Host	www.example.com
Port	80
User
Pass
Path	view.php
Query	Week=1
Fragment	#demo

Common HTTP status Codes:

Code	Meaning
200	Ok
204	NO Content
400	Bad Request
401	Unauthorized
50R	Forbidden
404	Not Found
408	Time Out
5**	Server Error

"example":

<?PHPfunctionCheck_url ($url){                //parsing URLs              $url _pieces=Parse_url($url); //set the correct path and port number              $path=(isset($url _pieces[' Path '])?$url _pieces[' Path ']: '/'; $port=(isset($url _pieces[' Port '])?$url _pieces[' Port ']: ' 80 '; //try connecting with Fsockopen ()              if($fp=Fsockopen($url _pieces[' Host '],$port,$errno,$errstr, 30)){                       //after successful establishment, write data to the server                     $send= "HEAD$pathHttp/1.1\r\n "; $send. = "HOST:$url _pieces[' host ']\r\n '; $send. = "connection:close\r\n\r\n"; fwrite($fp,$send); //Retrieving HTTP status codes                     $data=fgets($fp, 128); //Close Connection                     fclose($fp); //Return status Codes and class information                     List($response,$code) =Explode(‘ ‘,$data); if(code = = 200){                              return Array($code, ' good '); }Else{                              return Array($code, ' Bad ');//the second element of the array as the CSS class name                     }                }Else{                       //No connection                     return Array($errstr, ' bad '); }                        }         //Create a list of URLs       $urls=Array(                ' http://www.sdust.com ', ' http://www.example.com '         )         //to adjust the time limit for PHP scripts:       Set_time_limit(0);//Unlimited long time to complete tasks//validate URLs individually:       foreach($urls  as $url){                List($code,$class) = Check_url ($url); Echo"<p><a href =\"$url\ ">$url</a> (<span class =\ "$class\ ">$code</span>) </p> "; }  ?>

The advantage of using the Fsockopen () function is greater than the fopen () function: fopen () will only be used if Allow_url_fopen is set to true in php, and Fsockopen () is not limited.

PHP socket programming using the Fsockopen () function