On (01/11/17 14:48), Jonathan T. Leighton wrote: > > I would say that an IPv6 socket binds to an IPv4-mapped IPv6 > address, but yes - using it to connect to an IPv6 address would be > an application bug. It also think that having connect() spend 2 > minutes sending packets containing an illegal source address is a > bug. (And unfriendly!) I'll look into writing a patch for this, and > let you know whether or not I think I'm up to it. >
BTW, linux probably has a number of bugs in this space. you can do a number of "interesting" things, where the v4-mapped address ends up being treated as a global address. E.g., you can configure a v4 mapped address on an interface using /sbin/ip, then you can add an onlink route, like # ip -6 route add ::ffff:13.0.0.1 nexthop onlink dev eth1 and you can ping6 ::ffff:13.0.0.1, and (if you do this on both sides) watch a merry little packet exchange on the wire, where we send out an NS for ::ffff:13.0.0.1 to the solmcast of the v4 mapped address, the peer politely responds, and the 2 nodes then have a nice chat. I think the RFC states somewhere that you should never ever send out a v4 mapped address on the wire. --Sowmini
