POST адрес HTTP/1.0
Content-Type: multipart/form-data; boundary=некоторое_достаточно_уникальное_значение [boundary]
Host: хост
Content-Length: длина_содержимого
[boundary]
Content-Disposition: form-data; name="file"; filename="имя_файла"
Content-Type: image/jpeg (тип)

[содержимое картинки]
[boundary]

function post_file ($url, $avars) {		
	$parsed_url = parse_url($url);		
	$host = $parsed_url['host'];
	$path = $parsed_url['path'];	
		if($avars['type'] == 'content'){
		$file .= "filename=".$avars['filename']."&content=".$avars['value'];
	}
	if($avars['type'] == 'link'){
		$filetemp = file_get_contents($avars['value']);
		$filetopost = base64_encode($filetemp);
		$file .= "filename=".$avars['filename']."&content=".$filetopost;
	}
	if(isset($parsed_url['query'])) {			
		$query = $parsed_url['query'];			
	}					
	$socket = @fsockopen($host, 80, $errno, $errstr, $this->timeout) or die ("Не могу открыть сокет :".$errstr."(".$errno.")");	
	if ( isset($query) ) {				
		$out = "POST ".$path."?".$query." HTTP/1.1\r\n";				
	} else {				
		$out = "POST ".$path." HTTP/1.1\r\n";				
	}			
	$out .= "Host: ".$host."\r\n";			
	$out .= "User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; YPC 3.0.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)\r\n";
	$out .= "Content-Type: application/x-www-form-urlencoded\r\n";
	$out .= "Content-Length: ".strlen($file)."\r\n";
	if(!isset($headers['Connection'])) {						
		$out .= "Connection: Close\r\n";				
	}			
	$out .= "\r\n";	
	$out .= $file;
	fwrite($socket, $out);		
	while (!feof($socket)) {
		$in .= fgets($socket, 128);
	}		  
	fclose($socket);	
	return $in;						
}

(Request-Line)	POST /site.php?par=1 HTTP/1.1
Host: www.anysite.ru
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; ru; rv:1.9.0.10) Gecko/2009042316 Firefox/3.0.10
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-LanguageL: ru,en-us;q=0.7,en;q=0.3
Accept-Encoding: gzip,deflate
Accept-Charset: windows-1251,utf-8;q=0.7,*;q=0.7
Keep-Alive: 43200
Connection: keep-alive
Referer: http://www.anysite.ru/fol/
Cookie: PHPSESSID=2lpliicfgkjfnmjhbkm6dbn4t1
Content-Type: multipart/form-data; boundary=---------------------------21718375316139
Content-Length: 48176

Content-Type: multipart/form-data; boundary=---------------------------21718375316139
Content-Length: 48176

-----------------------------21718375316139
Content-Disposition: form-data; name="param1"

123
-----------------------------21718375316139
Content-Disposition: form-data; name="param2"

123
-----------------------------21718375316139
Content-Disposition: form-data; name="email"


-----------------------------21718375316139
Content-Disposition: form-data; name="imagefile"; filename="pic.jpeg"
Content-Type: image/jpeg

ÿØÿà�JFIF�


�H�H��ÿþ�;CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 80
ÿÛ�C�

(дальше пошло содержимое картинки)