fsockopen顺利，fwrite失败的原因有哪些

$matches = parse_url($url);
    !isset($matches['host']) && $matches['host'] = '';
    !isset($matches['path']) && $matches['path'] = '';
    !isset($matches['query']) && $matches['query'] = '';
    !isset($matches['port']) && $matches['port'] = '';
    $host = $matches['host'];
    $path = $matches['path'] ? $matches['path'].($matches['query'] ? '?'.$matches['query'] : '') : '/';
    $port = !empty($matches['port']) ? $matches['port'] : 80;
    if($post) {
        $out = "POST $path HTTP/1.0\r\n";
        $out .= "Accept: */*\r\n";
        $out .= "Accept-Language: zh-cn\r\n";
        $out .= "Content-Type: application/x-www-form-urlencoded\r\n";
        $out .= "User-Agent: $_SERVER[HTTP_USER_AGENT]\r\n";
        $out .= "Host: $host\r\n";
        $out .= 'Content-Length: '.strlen($post)."\r\n";
        $out .= "Connection: Close\r\n";
        $out .= "Cache-Control: no-cache\r\n";
        $out .= "Cookie: $cookie\r\n\r\n";
        $out .= $post;
    } else {
        $out = "GET $path HTTP/1.0\r\n";
        $out .= "Accept: */*\r\n";
        $out .= "Accept-Language: zh-cn\r\n";
        $out .= "User-Agent: $_SERVER[HTTP_USER_AGENT]\r\n";
        $out .= "Host: $host\r\n";
        $out .= "Connection: Close\r\n";
        $out .= "Cookie: $cookie\r\n\r\n";
    }
    
    $fp = @fsockopen(($ip ? $ip : $host), $port, $errno, $errstr, $timeout);
    
    if(!$fp) {
        return '';//note $errstr : $errno \r\n
    } else {
        stream_set_blocking($fp, $block);
        stream_set_timeout($fp, $timeout);var_dump($fp);
        @fwrite($fp, $out);
//注释标记
        /*$status = stream_get_meta_data($fp);
        if(!$status['timed_out']) {
            while (!feof($fp)) {
                if(($header = @fgets($fp)) && ($header == "\r\n" ||  $header == "\n")) {
                    break;
                }
            }

            $stop = false;
            while(!feof($fp) && !$stop) {
                $data = fread($fp, ($limit == 0 || $limit > 8192 ? 8192 : $limit));
                $return .= $data;
                if($limit) {
                    $limit -= strlen($data);
                    $stop = $limit <= 0;
                }
            }
        }*/
//注释标记
        @fclose($fp);
        return true;
    }

/* 对于楼主的应用, 这里得到的是TCP套接字的一些信息 */
        $status = stream_get_meta_data($fp);
/* 这里是检查TCP连接是否超时 */
        if(!$status['timed_out']) {
/* 如果没有超时, 那么就读取数据, 直到碰到文件结束符 */
            while (!feof($fp)) {
/* 由于这里是读取HTTP头信息, 空行标识头信息结束, 因此需要break */
                if(($header = @fgets($fp)) && ($header == "\r\n" ||  $header == "\n")) {
                    break;
                }
            }
/* 这里是读取HTTP的body, 个人认为这里的处理有一些粗糙, 至少先看看HTTP响应头中有没有Content-Length根据它进行处理, 如果没有再如下读取 */
            $stop = false;
            while(!feof($fp) && !$stop) {
/* 读取最多8192字节($limit递减) */
                $data = fread($fp, ($limit == 0 || $limit > 8192 ? 8192 : $limit));
/* 将读取到的内容连接到返回字符串中 */
                $return .= $data;
                if($limit) {
                    $limit -= strlen($data);
                    $stop = $limit <= 0;
                }
            }
        }

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