然后服务器可以验证是否选中有效选项，并根据接收到的输入重定向输出。
The server can then validate that a valid option was selected and redirect the output based on the input received.
一个指向队列末尾包的选项可能会迫使接收方的TCP协议栈遍历整个队列以判断此选项指向哪一个包。
An option that refers to a packet at the end of the queue may require a full list traversal by the receiving TCP stack in order to identify which packet the option refers to.
对于第一个get，我们指定不需要任何匹配选项——准备接收任何组中的第一条消息。
For the first get, we specify that no match options are required — we are prepared to receive the first message in any group.
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