On returning to the tcp_usrreq function, the socket descriptor is made to point to the socket's TCP control block.

在返回到tcp_usrreq函数时，创建套接字描述符，以指向套接字的tcp控制块。

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Within in_pcballoc, the kernel's memory allocator function is called, which allocates memory to the Internet control block.

在 in_pcballoc 中，调用了内核的内存分配器函数，该函数将内存分配给 Internet 控制块。

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The switch in the tcp_usrreq function calls in_setpeeraddr(), which copies the foreign IP address and foreign port number from the protocol control block and returns these to the server process.

tcp_usrreq 函数中的切换调用 in_setpeeraddr()，后者从协议控制块复制外来 IP 地址和外来端口号，并将其返回到服务器进程。

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