这里看看数据包从IP层是如何交给传输层来处理的,为了方便,这里传输层以UDP协议为例来分析。 从ip_rcv()函数中可以看到 /* * Pass on the datagram to each protocol that wants it, * based on the datagram protocol. We should really * check the protocol handler's return values here... */ ipprot->handler(skb2, dev, opts_p ? &opt : 0