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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Oncologists and pharmaceutical researchers are studying ways to find and block those mutations, aiming to turn off the switch that sparks carcinogenesis.