UNIX socket advanced learning diary -ipv4-ipv6 interoperability

Due to transition ,IPV4 To IPV6 The transformation of is not achieved overnight , Therefore, we need to consider the possibility of both in the long run ;

That is, we need to keep clientIPV4 And IPV6,IPV4 Of Server signal communication ;client IPV6 And IPV6,IPV4 Of Server signal communication

Rule compliance ： Backward compatibility

1.IPV4 Intelligent reception comes from IPV4 External links from customers ;

2. If the server has a wildcard address bound IPV6 monitor SOCKET, And the option is set IPV6_V6ONLY Options , Then it can receive V4, It can be accepted again V6 External connections , For those from IPV4 For customer connections , The local address of the server will be with a local IPV4 Address corresponding IPV4 The mapping of IPV6 Address ;

3. If the server has one IPV6 monitor SOCKET, And bound to it is division IPV4 The mapping of IPV6 A non universal configuration other than the address IPV6 Address , Or the generic address is set IPV6_V6ONLY Options , Then it can only receive from IPV6 The connection of .

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