To allocate an Internet protocolcontrolblock, in_pcballoc() is called.
要分配 Internet 协议控制块，可调用 in_pcballoc()。
2
The switch in the tcp_usrreq function calls in_setpeeraddr(), which copies the foreign IP address and foreign port number from the protocolcontrolblock 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。