中文(繁體)
中文(繁體)
在PHP 中，基於Socket 的雙向通信是一種常見的網絡編程任務。當涉及到高效的消息傳遞時， socket_sendmsg和socket_recvmsg這兩個函數可以提供更高級的功能，幫助開發者實現更加靈活和復雜的通信模式。本文將探討如何使用socket_sendmsg配合socket_recvmsg來實現雙向通信。
首先，我們需要了解這兩個函數的基本使用：
socket_sendmsg ：此函數用於向指定的Socket 發送數據，並且可以通過它傳遞附加的標誌、控制信息或附件數據。它與socket_send的主要區別在於， socket_sendmsg提供了更強大的靈活性，能夠支持更複雜的數據結構。
socket_recvmsg ：此函數則是用於從一個Socket 接收消息。它可以接收的消息不僅包含數據，還可能包含一些控制信息，如發送者的地址、數據的元數據等。與socket_recv相比，它能夠返回更多的通信信息，使得雙向通信更為靈活。
在實際的應用中，雙向通信往往意味著雙方需要能夠互相發送和接收數據。借助於socket_sendmsg和socket_recvmsg ，我們能夠高效地實現這一目標。這兩個函數可以通過控制消息頭部和數據部分的方式，進行更加靈活的交互。
首先，我們需要初始化一個Socket，通常通過socket_create函數創建一個TCP 或UDP 類型的Socket。接下來，我們可以使用socket_bind或socket_connect來進行綁定或連接。
<span><span><span class="hljs-comment">// 創建 Socket</span></span><span>
</span><span><span class="hljs-variable">$socket</span></span><span> = </span><span><span class="hljs-title function_ invoke__">socket_create</span></span><span>(AF_INET, SOCK_STREAM, SOL_TCP);
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$socket</span></span><span> === </span><span><span class="hljs-literal">false</span></span><span>) {
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Socket 創建失败: "</span></span><span> . </span><span><span class="hljs-title function_ invoke__">socket_strerror</span></span><span>(</span><span><span class="hljs-title function_ invoke__">socket_last_error</span></span><span>());
</span><span><span class="hljs-keyword">exit</span></span><span>();
}
</span><span><span class="hljs-comment">// 連接到服務器</span></span><span>
</span><span><span class="hljs-variable">$address</span></span><span> = </span><span><span class="hljs-string">'127.0.0.1'</span></span><span>;
</span><span><span class="hljs-variable">$port</span></span><span> = </span><span><span class="hljs-number">8080</span></span><span>;
</span><span><span class="hljs-variable">$result</span></span><span> = </span><span><span class="hljs-title function_ invoke__">socket_connect</span></span><span>(</span><span><span class="hljs-variable">$socket</span></span><span>, </span><span><span class="hljs-variable">$address</span></span><span>, </span><span><span class="hljs-variable">$port</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$result</span></span><span> === </span><span><span class="hljs-literal">false</span></span><span>) {
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"連接失敗: "</span></span><span> . </span><span><span class="hljs-title function_ invoke__">socket_strerror</span></span><span>(</span><span><span class="hljs-title function_ invoke__">socket_last_error</span></span><span>());
</span><span><span class="hljs-keyword">exit</span></span><span>();
}
</span></span>socket_sendmsg函數能夠讓我們發送包含複雜數據結構的消息。通常，它會把數據封裝到一個msghdr結構中，可以包含附加的控制信息。例如，指定發送的標誌位、附加數據、目的地地址等。
<span><span><span class="hljs-variable">$msg</span></span><span> = </span><span><span class="hljs-string">"Hello, Server!"</span></span><span>;
</span><span><span class="hljs-variable">$len</span></span><span> = </span><span><span class="hljs-title function_ invoke__">strlen</span></span><span>(</span><span><span class="hljs-variable">$msg</span></span><span>);
</span><span><span class="hljs-comment">// 創建一个消息头</span></span><span>
</span><span><span class="hljs-variable">$msgHdr</span></span><span> = </span><span><span class="hljs-keyword">array</span></span><span>(
</span><span><span class="hljs-string">'msg_name'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>, </span><span><span class="hljs-comment">// 默認目標地址為空</span></span><span>
</span><span><span class="hljs-string">'msg_namelen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_iov'</span></span><span> => </span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-string">'iov_base'</span></span><span> => </span><span><span class="hljs-variable">$msg</span></span><span>, </span><span><span class="hljs-string">'iov_len'</span></span><span> => </span><span><span class="hljs-variable">$len</span></span><span>)), </span><span><span class="hljs-comment">// 數據內容</span></span><span>
</span><span><span class="hljs-string">'msg_iovlen'</span></span><span> => </span><span><span class="hljs-number">1</span></span><span>,
</span><span><span class="hljs-string">'msg_control'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>,
</span><span><span class="hljs-string">'msg_controllen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_flags'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>
);
</span><span><span class="hljs-comment">// 發送消息</span></span><span>
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">socket_sendmsg</span></span><span>(</span><span><span class="hljs-variable">$socket</span></span><span>, </span><span><span class="hljs-variable">$msgHdr</span></span><span>) === </span><span><span class="hljs-literal">false</span></span><span>) {
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"發送失敗: "</span></span><span> . </span><span><span class="hljs-title function_ invoke__">socket_strerror</span></span><span>(</span><span><span class="hljs-title function_ invoke__">socket_last_error</span></span><span>());
</span><span><span class="hljs-keyword">exit</span></span><span>();
}
</span></span>socket_recvmsg函數與socket_sendmsg相反，用於從Socket 接收包含複雜數據的消息。它返回的消息除了數據部分，還可能包含發送者的地址、標誌等信息。
<span><span><span class="hljs-comment">// 準備接收消息的緩衝區</span></span><span>
</span><span><span class="hljs-variable">$buf</span></span><span> = </span><span><span class="hljs-string">""</span></span><span>;
</span><span><span class="hljs-variable">$bufLen</span></span><span> = </span><span><span class="hljs-number">1024</span></span><span>;
</span><span><span class="hljs-variable">$msgHdrRecv</span></span><span> = </span><span><span class="hljs-keyword">array</span></span><span>(
</span><span><span class="hljs-string">'msg_name'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>,
</span><span><span class="hljs-string">'msg_namelen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_iov'</span></span><span> => </span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-string">'iov_base'</span></span><span> => &</span><span><span class="hljs-variable">$buf</span></span><span>, </span><span><span class="hljs-string">'iov_len'</span></span><span> => </span><span><span class="hljs-variable">$bufLen</span></span><span>)),
</span><span><span class="hljs-string">'msg_iovlen'</span></span><span> => </span><span><span class="hljs-number">1</span></span><span>,
</span><span><span class="hljs-string">'msg_control'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>,
</span><span><span class="hljs-string">'msg_controllen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_flags'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>
);
</span><span><span class="hljs-comment">// 接收消息</span></span><span>
</span><span><span class="hljs-variable">$bytesReceived</span></span><span> = </span><span><span class="hljs-title function_ invoke__">socket_recvmsg</span></span><span>(</span><span><span class="hljs-variable">$socket</span></span><span>, </span><span><span class="hljs-variable">$msgHdrRecv</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$bytesReceived</span></span><span> === </span><span><span class="hljs-literal">false</span></span><span>) {
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"接收失敗: "</span></span><span> . </span><span><span class="hljs-title function_ invoke__">socket_strerror</span></span><span>(</span><span><span class="hljs-title function_ invoke__">socket_last_error</span></span><span>());
</span><span><span class="hljs-keyword">exit</span></span><span>();
}
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"接收到消息: "</span></span><span> . </span><span><span class="hljs-variable">$buf</span></span><span> . </span><span><span class="hljs-string">"\n"</span></span><span>;
</span></span>在實際使用中，雙向通信的基本流程可以概括為以下幾個步驟：
連接建立：客戶端通過socket_connect連接到服務器，服務器通過socket_accept等待客戶端連接。
發送消息：客戶端或服務器可以通過socket_sendmsg發送消息。需要注意的是，可以傳遞附加的數據或標誌位來表示特定的控制信息。
接收消息：接收方通過socket_recvmsg接收消息。收到的消息不僅僅包括數據部分，還包括一些元數據（如消息標誌、發送者等信息）。
交替發送和接收：客戶端和服務器交替使用socket_sendmsg和socket_recvmsg進行雙向數據交換。每次發送時，可以附加不同的控制信息或更複雜的數據結構。
<span><span><span class="hljs-comment">// 服務器端代碼示例（簡化版）</span></span><span>
</span><span><span class="hljs-variable">$serverSocket</span></span><span> = </span><span><span class="hljs-title function_ invoke__">socket_create</span></span><span>(AF_INET, SOCK_STREAM, SOL_TCP);
</span><span><span class="hljs-title function_ invoke__">socket_bind</span></span><span>(</span><span><span class="hljs-variable">$serverSocket</span></span><span>, </span><span><span class="hljs-string">'127.0.0.1'</span></span><span>, </span><span><span class="hljs-number">8080</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">socket_listen</span></span><span>(</span><span><span class="hljs-variable">$serverSocket</span></span><span>);
</span><span><span class="hljs-comment">// 等待客戶端連接</span></span><span>
</span><span><span class="hljs-variable">$clientSocket</span></span><span> = </span><span><span class="hljs-title function_ invoke__">socket_accept</span></span><span>(</span><span><span class="hljs-variable">$serverSocket</span></span><span>);
</span><span><span class="hljs-comment">// 接收並發送數據</span></span><span>
</span><span><span class="hljs-variable">$buffer</span></span><span> = </span><span><span class="hljs-string">''</span></span><span>;
</span><span><span class="hljs-variable">$header</span></span><span> = </span><span><span class="hljs-keyword">array</span></span><span>(
</span><span><span class="hljs-string">'msg_name'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>,
</span><span><span class="hljs-string">'msg_namelen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_iov'</span></span><span> => </span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-string">'iov_base'</span></span><span> => &</span><span><span class="hljs-variable">$buffer</span></span><span>, </span><span><span class="hljs-string">'iov_len'</span></span><span> => </span><span><span class="hljs-number">1024</span></span><span>)),
</span><span><span class="hljs-string">'msg_iovlen'</span></span><span> => </span><span><span class="hljs-number">1</span></span><span>,
</span><span><span class="hljs-string">'msg_control'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>,
</span><span><span class="hljs-string">'msg_controllen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_flags'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>
);
</span><span><span class="hljs-keyword">while</span></span><span> (</span><span><span class="hljs-literal">true</span></span><span>) {
</span><span><span class="hljs-variable">$bytesReceived</span></span><span> = </span><span><span class="hljs-title function_ invoke__">socket_recvmsg</span></span><span>(</span><span><span class="hljs-variable">$clientSocket</span></span><span>, </span><span><span class="hljs-variable">$header</span></span><span>);
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$bytesReceived</span></span><span> === </span><span><span class="hljs-literal">false</span></span><span>) {
</span><span><span class="hljs-keyword">break</span></span><span>;
}
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"收到來自客戶端的消息: <span class="hljs-subst">$buffer</span></span></span><span>\n";
</span><span><span class="hljs-comment">// 向客戶端發送回應</span></span><span>
</span><span><span class="hljs-variable">$msg</span></span><span> = </span><span><span class="hljs-string">"Hello from server!"</span></span><span>;
</span><span><span class="hljs-variable">$msgHdrSend</span></span><span> = </span><span><span class="hljs-keyword">array</span></span><span>(
</span><span><span class="hljs-string">'msg_name'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>,
</span><span><span class="hljs-string">'msg_namelen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_iov'</span></span><span> => </span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-keyword">array</span></span><span>(</span><span><span class="hljs-string">'iov_base'</span></span><span> => </span><span><span class="hljs-variable">$msg</span></span><span>, </span><span><span class="hljs-string">'iov_len'</span></span><span> => </span><span><span class="hljs-title function_ invoke__">strlen</span></span><span>(</span><span><span class="hljs-variable">$msg</span></span><span>))),
</span><span><span class="hljs-string">'msg_iovlen'</span></span><span> => </span><span><span class="hljs-number">1</span></span><span>,
</span><span><span class="hljs-string">'msg_control'</span></span><span> => </span><span><span class="hljs-literal">null</span></span><span>,
</span><span><span class="hljs-string">'msg_controllen'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>,
</span><span><span class="hljs-string">'msg_flags'</span></span><span> => </span><span><span class="hljs-number">0</span></span><span>
);
</span><span><span class="hljs-title function_ invoke__">socket_sendmsg</span></span><span>(</span><span><span class="hljs-variable">$clientSocket</span></span><span>, </span><span><span class="hljs-variable">$msgHdrSend</span></span><span>);
}
</span></span>使用socket_sendmsg和socket_recvmsg函數可以大大提高基於Socket 的通信效率，特別是在需要處理複雜消息或傳遞附加控制信息的場景下。它們的靈活性讓開發者能夠更好地實現雙向通信，通過輪詢和控制消息來完成數據的交換。理解這些函數的使用方式，對於實現高效的網絡通信至關重要。
