Added support for IPv6 to Reachability

[kcharwood]

Added IPv6 support for Reachability based on the work from @SAMUKEI in #3171

[mkantor]

Not sure if this is the best place to ask, but I couldn't find a solid answer when googling and GitHub makes it easy to ask publicly:

Does this changeset imply that iOS apps using AFNetworking 2.x's reachability manager could incur the wrath of Apple on 2016-06-01, when IPv6-only support will be required? Does AFNetworking 2.x work correctly in IPv6-only networks?

[sunuslee]

@mkantor
i want this as well:)

[abournier]

Same question for me. Does AFNetworking 2.x work correctly in IPv6-only networks?

[SamehDamuni]

Same question but for AFNetworking 3.x, does it work correctly in IPv6-only networks?

[qiumikee]

Same question for me.

[abournier]

I have created a NAT64 sharing internet connection as Apple recommended to test on IPv6 only, and all seems to work for my app.

[sergey-nikolaev-paycasso]

@abournier you mean the 2.x version of AFNetworking?

[abournier]

Yes, the 2.6.x.

[ryancrosby]

@abournier there also is some discussion related to this in #3496 related to AFNetworking 2.x supporting IPv6, probably better to keep discussion around version 2.x there rather than here which is focusing on 3.x.

[abournier]

Thanks for the info. I will post on the other thread.

[cezheng]

As apple has updated the Official Reachability sample code, and claims that the class fully supports IPv6. But when we look at the code, it is still using sockaddr_in in the reachabilityForInternetConnection method, which makes me kind of confused.

@kcharwood However this PR actually uses ``sockaddr_in6` on iOS 9 or later. Will such implementation fail to work correctly if the device happens to be connecting to a IPv4 only network?

[hei9gag]

It seems the Reachability function is not compatible to iOS 7. The function returns no reachable status even I have connected to a NAT64 share network.

Also I found that reachabilityDidChange is slightly delay to trigger in iOS 8 (compare to iOS 9) when I try to connect to a IPv6 network from no network status. Is this a bug or iOS 7 isn't support NAT64? Many thanks.

[kenmaz]

@cezheng
https://forums.developer.apple.com/message/137546#137546
Apple's engineer say 0.0.0.0 address is treated as special token, it can be use for checking local connection. Therefore, in this situation, sockaddr_in / AF_INET works good in IPv4 and Pv6 Network.