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       很多朋友的公司或家里有一台上网的机器，这些上网的机器有些能够获得公网IP，但是这些IP通常不固定。

       大家都想充分利用这些上网设备的网络能力来搭建服务器环境，但由于IP地址老是变化，因此，即使是给这些机器分配了域名，也时常无法访问。于是，很多人想到了动态域名解析，即域名不变，IP地址变化，域名解析记录能够跟随IP地址变化，目前市场上有几种商业的解析方案实现，例如花生壳，更多的就不举例了，避免给他们做免费广告。这些都要收费，而且可能要通过CNAME（将您的域名解析成别人的域名）方式来解决，解析效率略有降低。

       好在阿里云的开放精神，他们将域名解析的接口提供了给大家，经过笔者测试非常好用。

       本文将实现自己的免费动态域名解析实现分享出来，实现思路如下：

      1）首先有一台公网的固定域名的服务器，运行一个助手程序（getipd），来帮助获得动态IP主机的当前IP地址（一般几天变化一次）；

      2）在动态IP的机器上（或者跨越该路由器的内部网络主机）运行PHP编写的客户端，PHP编写的客户端定期与公网那个运行getipd的服务器通信，一般10秒一次，获得自己的公网IP；

      3）客户端程序判断，如果自己的公网IP发生变化，则调用阿里云的接口来更改域名（A记录），阿里云的DNS动态解析真的非常快，一般是实时生效的。

一、PHP客户端的实现所有源代码如下（完整实现 dnsupdater.php,不依赖任何第三方库）：

    0) {	if (!empty($options['d']))		$show_log = True;}if (!function_exists('random_int')) {	//php 5.x compatible	function random_int($min,$max) {		return mt_rand($min,$max);	}}/** * Class AlicloudDNSUpdater */class AlicloudDNSUpdater {    /**     * @var string     */    public $domainName;    /**     * @var string     */    public $rR;    /**     * @var string     */    public $type;    /**     * @var string     */    public $value;    /**     * @var string     */    public $accessKeyId;    /**     * @var string     */    public $accessKeySecret;    /**     * AlicloudUpdateRecord constructor.     *     * @param string $accessKeyId     * @param string $accessKeySecret     */    function __construct(        $accessKeyId,        $accessKeySecret    ) {        $this->accessKeyId     = $accessKeyId;        $this->accessKeySecret = $accessKeySecret;    }    /**     * @param string $CanonicalQueryString     * @return string     */    public function getSignature($CanonicalQueryString)    {        $HTTPMethod                  = 'GET';        $slash                       = urlencode('/');        $EncodedCanonicalQueryString = urlencode($CanonicalQueryString);        $StringToSign                = "{$HTTPMethod}&{$slash}&{$EncodedCanonicalQueryString}";        $StringToSign                = str_replace('%40', '%2540', $StringToSign);        $HMAC                        = hash_hmac('sha1', $StringToSign, "{$this->accessKeySecret}&", true);        return base64_encode($HMAC);    }    /**     * @return string     */    public function getDate()    {        $timestamp = date('U');        $date      = date('Y-m-d', $timestamp);        $H         = date('H', $timestamp);        $i         = date('i', $timestamp);        $s         = date('s', $timestamp);        return "{$date}T{$H}%3A{$i}%3A{$s}";    }    /**     * @return string     * @throws Exception     */    public function getRecordId()    {        $queries = [            'AccessKeyId' => $this->accessKeyId,            'Action' => 'DescribeDomainRecords',            'DomainName' => $this->domainName,            'Format' => 'json',            'SignatureMethod' => 'HMAC-SHA1',            'SignatureNonce' => random_int(1000000000, 9999999999),            'SignatureVersion' => '1.0',            'Timestamp' => $this->getDate(),            'Version' => '2015-01-09'        ];        $response = $this->doRequest($queries);		if (!isset($response['DomainRecords'])) {			return '';		}		        $recordList = $response['DomainRecords']['Record'];        $RR = null;        foreach ($recordList as $key => $record) {            if ($this->rR === $record['RR']) {                $RR = $record;            }        }        if ($RR === null) {            //die('RR ' . $this->rR . ' not found.');			return '';        }        return $RR['RecordId'];    }    /**     * @param string $domainName     */    public function setDomainName($domainName)    {        $this->domainName = $domainName;    }    /**     * @param string $value     */    public function setValue($value)    {        $this->value = $value;    }    /**     * @param string $rR     */    public function setRR($rR)    {        $this->rR = $rR;    }    /**     * @param string $recordId     */    public function setRecordId($recordId)    {        $this->recordId = $recordId;    }    /**     * @param string $type     */    public function setRecordType($type)    {        $this->type = $type;    }    /**     * @param array $queries     * @return array     */    public function doRequest($queries)    {        $CanonicalQueryString = '';        $i                    = 0;        foreach ($queries as $param => $query) {            $CanonicalQueryString .= $i === 0 ? null : '&';            $CanonicalQueryString .= "{$param}={$query}";            $i++;        }        $signature  = $this->getSignature($CanonicalQueryString);        $requestUrl = "http://dns.aliyuncs.com/?{$CanonicalQueryString}&Signature=" . urlencode($signature);        $response   = file_get_contents($requestUrl, false, stream_context_create([            'http' => [                'ignore_errors' => true            ]        ]));        return json_decode($response, true);    }    /**     * @return array     * @throws \Exception     */    public function sendRequest()    {		$RecordId = $this->getRecordId();		if (empty($RecordId)) {			return Array(				'Code'=>'Error',				'Message'=>$this->domainName .' record not found'			);		}		        $queries = [            'AccessKeyId' => $this->accessKeyId,            'Action' => 'UpdateDomainRecord',            'Format' => 'json',            'RR' => $this->rR,            'RecordId' => $RecordId,            'SignatureMethod' => 'HMAC-SHA1',            'SignatureNonce' => random_int(1000000000, 9999999999),            'SignatureVersion' => '1.0',            'Timestamp' => $this->getDate(),            'Type' => $this->type,            'Value' => $this->value,            'Version' => '2015-01-09'        ];        return $this->doRequest($queries);    }		public function sendAddRequest()    {        $queries = [            'AccessKeyId' => $this->accessKeyId,            'Action' => 'AddDomainRecord',            'Format' => 'json',            'RR' => $this->rR,			'Type' => $this->type,            'Value' => $this->value,            'DomainName' => $this->domainName,            'SignatureMethod' => 'HMAC-SHA1',            'SignatureNonce' => random_int(1000000000, 9999999999),            'SignatureVersion' => '1.0',            'Timestamp' => $this->getDate(),            'Version' => '2015-01-09'        ];        return $this->doRequest($queries);    }}while(true) {	$client = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);	$result = @socket_connect($client, $iphelper_addr, $iphelper_port);	if (!$result) {		if ($show_log) {			echo "socket_connect() failed: reason: " . socket_strerror(socket_last_error($client)) . "\n";		}		socket_close($client);	}	else {		$login_info = Array(			'server'=>'server 1',			'time'=>time()		);				socket_write($client, json_encode($login_info));				$response = @socket_read($client, 1024);				if ($response !== False && !empty($response) ) {			$info = json_decode($response,True);			if (is_array($info) && isset($info['ip'])) {				if ($old_gateway_ip != $info['ip']) {					if ($show_log) {						echo date('Y-m-d H:i:s'). " do refresh dns ip :".$info['ip']."\n";					}					$updater         = new AlicloudDNSUpdater($AccessKeyId, $AccessKeySecret);																						foreach($domain_list as $domain) {						$dotpos = strpos($domain,'.');												if ($dotpos !== False) {							$recoreName = substr($domain,0,$dotpos);							$domainName = substr($domain,$dotpos + 1);							if ($show_log) {								echo 'Update DNS Record:'.$recoreName.'.'.$domainName .' -> '. $info['ip'] ."...\n";							}														$updater->setDomainName($domainName);							$updater->setRecordType('A');							$updater->setRR($recoreName);							$updater->setValue($info['ip']);							$result = $updater->sendRequest();							if ($show_log) {								print_r($result);																echo "\n";							}						}					}															$old_gateway_ip = $info['ip'];				}				else {					if ($show_log) {						echo "IP:{$old_gateway_ip} keep!\n";					}				}			}		}					socket_close($client);	}			Sleep(10);}

其中：$AccessKeyId ，$AccessKeySecret 是阿里云分配给你的，只要您能够登录阿里云的控制台即可获取。获取位置如下：

公网IP地址获取服务的主机地址 $iphelper_addr 可以修改，为了能够快速测试，可以暂时用  网站提供的，请仅作为临时测试使用，正式使用时请搭建自己的服务器端。

$domain_list 为需要刷新的IP地址列表，请先在阿里云的控制台的域名解析操作页面添加初始化解析记录，例如www.domain.com,live.domain.com 等，添加解析记录时的IP地址可以是任何值，以后dnsupdater.php会修改这个值的。

将dnsupdater.php 下载下来，并设置好必要的$AccessKeyId ，$AccessKeySecret 变量，假设PHP解释器安装在C:\PHP7\php.exe,运行 如下命令即可:

C:\PHP7\php.exe dnsupdater.php 

请用php5.6以上运行本客户端。PHP需要开启sockets扩展，即去掉php.ini里的如下行的注释（去掉分号）

extension=php_sockets.dll

如果想让dnsupdater.php 在后台运行，请用RunHiddenConsole.exe,这是一个用于隐藏Windows控制台窗口的助手程序，官方网址是：

dnsupdater.php　代码完全可以运行在linux上，在linux系统的shell里输入：

　php dnsupdater.php &

可以作为守护进程长期运行。

二、getipd服务器端程序，这是一个用于帮助获取公网IP地址的极其简单的TCP服务器，笔者用C语言与PHP分别实现了一份，用PHP实现的 getip.php（仅仅一个文件）如下，请用PHP解释器执行：

在linux里输入 php getip.php & 即可执行。

用C语言实现的getip.c代码如下，需要编译成可执行程序：

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              #define closesocket(s) close(s)#endif#define MYPORT 8198 // the port users will be connecting to#define BACKLOG 5 // how many pending connections queue will hold#define BUF_SIZE 512int fd_A[BACKLOG]; // accepted connection fdint conn_amount = 0; // current connection amountvoid showclient(){ int i; printf("client amount: %d\n", conn_amount); for (i = 0; i < BACKLOG; i++) { printf("[%d]:%d ", i, fd_A[i]); } printf("\n\n");}const char * g_app_dir = NULL;const char * g_exe_name = "getipd";volatile long g_b_exit_server = 0;int g_web_root_len = 4;int g_app_dir_len = 0;#ifdef _WIN32#define PATH_DEL '\\'#define PTHREAD_INITIALIZED {0,0}#else#define PATH_DEL '/'#define PTHREAD_INITIALIZED 0#endif#undef MAX_PATH #ifndef MAX_PATH#define MAX_PATH 1024#endifchar g_cur_exe_path[MAX_PATH];void getExePath(){ char * pch;#ifdef _WIN32 GetModuleFileNameA(NULL,g_cur_exe_path,ARRAYSIZE(g_cur_exe_path)); pch = strrchr(g_cur_exe_path,'\\'); pch ++ ; *pch = '\0';#else int cnt = readlink("/proc/self/exe", g_cur_exe_path, MAX_PATH); if (cnt < 0 || cnt >= MAX_PATH) { strcpy(g_cur_exe_path,"/usr/local/"); } pch = strrchr(g_cur_exe_path,'/'); if (pch) { pch ++; *pch = 0; }#endif g_app_dir = g_cur_exe_path; g_app_dir_len = strlen(g_app_dir);}#ifdef _WIN32void init_daemon() {};#else#ifndef NOFILE #define NOFILE 3 #endifvoid init_daemon(){ int pid; int i; pid=fork(); if(pid<0) exit(1); else if(pid>0) exit(0); setsid(); pid=fork(); if(pid>0) exit(0); else if(pid<0) exit(1); for(i=0;i
              
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                    \n" "Parameters:\n" "\t-p tcp port,default: [%s]\n" DAEMON_HINT, progname,debug,MYPORT ); exit(1);}int main(int argc,char * argv[]){ int sock_fd, new_fd; // listen on sock_fd, new connection on new_fd struct sockaddr_in server_addr; // server address information struct sockaddr_in client_addr; // connector's address information socklen_t sin_size; int yes = 1,b_daemon = 0; char buf[BUF_SIZE]; int ret; int i; fd_set fdsr; int maxsock,remove_count; struct timeval tv; unsigned short port = MYPORT;#ifdef WIN32 WSADATA wsaData; WORD wVersionRequested; wVersionRequested =MAKEWORD( 1, 1 ); ret = WSAStartup( wVersionRequested, &wsaData ); if ( ret != 0 ) { /* Tell the user that we couldn't find a useable */ /* winsock.dll. */ exit(1); }#endif getExePath(); g_exe_name = strrchr(argv[0],PATH_DEL); if (g_exe_name) { g_exe_name ++; } else { g_exe_name = argv[0]; } /* Parse command line arguments */ for (i = 1; i < argc; i++) { if (strcmp(argv[i], "-p") == 0) { port = atoi(argv[++i]); } else if (!strcmp(argv[i],"-d")) { b_daemon = 1; break; } else if (!strcmp(argv[i],"-?") || !strcmp(argv[i],"-h")) { Usage(); break; } } if (b_daemon) { init_daemon(); } if ((sock_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) { perror("socket"); exit(1); } if (setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, (const char*)&yes, sizeof(int)) == -1) { perror("setsockopt"); exit(1); } server_addr.sin_family = AF_INET; // host byte order server_addr.sin_port = htons(MYPORT); // short, network byte order server_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP memset(server_addr.sin_zero, '\0', sizeof(server_addr.sin_zero)); if (bind(sock_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) { perror("bind"); exit(1); } if (listen(sock_fd, BACKLOG) == -1) { perror("listen"); exit(1); } printf("listen port %d\n", MYPORT); conn_amount = 0; sin_size = sizeof(client_addr); maxsock = sock_fd; memset(fd_A,0,sizeof (fd_A)); while (1) { // timeout setting tv.tv_sec = 30; tv.tv_usec = 0; // initialize file descriptor set FD_ZERO(&fdsr); FD_SET(sock_fd, &fdsr); // add active connection to fd set for (i = 0; i < BACKLOG; i++) { if (fd_A[i] != 0) { FD_SET(fd_A[i], &fdsr); } } ret = select(maxsock + 1, &fdsr, NULL, NULL, &tv); if (ret < 0) { perror("select"); break; } else if (ret == 0) { printf("timeout\n"); continue; } remove_count = 0; // check every fd in the set for (i = 0; i < conn_amount; i++) { if (FD_ISSET(fd_A[i], &fdsr)) { ret = recv(fd_A[i], buf, sizeof(buf), 0); if (ret <= 0) { // client close printf("client[%d] close\n", i); closesocket(fd_A[i]); FD_CLR(fd_A[i], &fdsr); fd_A[i] = 0; remove_count ++; } else { // receive data int ret2; char ipAddr[128]; if (ret < BUF_SIZE) memset(&buf[ret], '\0', 1); printf("client[%d] send:%s\n", i, buf); sin_size = sizeof(client_addr); ret2 = getpeername(fd_A[i],(struct sockaddr *)&client_addr, &sin_size); if (ret2 == 0) { int len = sprintf(buf,"{\"ip\":\"%s\"}", inet_ntop(AF_INET, &client_addr.sin_addr, ipAddr, sizeof(ipAddr))); send(fd_A[i], buf, len, 0); remove_count ++; closesocket(fd_A[i]); FD_CLR(fd_A[i], &fdsr); fd_A[i] = 0; } } } } //resort the socket if (remove_count > 0) { int j=0; for (i = 0; i < conn_amount; i++) { if (fd_A[i]) { fd_A[j] = fd_A[i]; j++; } } for (i = j; i < conn_amount; i++) { fd_A[i] = 0; } conn_amount -= remove_count; } // check whether a new connection comes if (FD_ISSET(sock_fd, &fdsr)) { new_fd = accept(sock_fd, (struct sockaddr *)&client_addr, &sin_size); if (new_fd <= 0) { perror("accept"); continue; } // add to fd queue if (conn_amount < BACKLOG) { char ipAddr[128]; fd_A[conn_amount++] = new_fd; printf("new connection client[%d] %s:%d\n", conn_amount, inet_ntop(AF_INET, &client_addr.sin_addr, ipAddr, sizeof(ipAddr)), ntohs(client_addr.sin_port)); if (new_fd > maxsock) maxsock = new_fd; } else { printf("max connections arrived, exit\n"); send(new_fd, "bye", 3, 0); closesocket(new_fd); break; } } showclient(); } // close other connections for (i = 0; i < conn_amount; i++) { if (fd_A[i] != 0) { closesocket(fd_A[i]); } }#ifdef WIN32 WSACleanup();#endif exit(0);}
                  
                 
                
               
              
             
            
           
          
         
        
       
      
     
    
   

getip.c 如果要在Windows下编译请用VC新建一个简单项目，添加此文件即可;

在linux下编译请用:

 gcc -O2 -o getipd getip.c

在linux下通过以上命令编译后，输入 ./getipd -d 即以守护进程的方式运行。getipd 用到了8198端口，请注意修改防火墙的规则，打开此端口。

至此，一个属于自己的高效的动态域名解析系统就完成了。

所有代码可以在

下载。

转载地址：http://xuvfb.baihongyu.com/