cidrhost performing incorrect operations in IPv6

[mlosapio]

The library which cidrhost relies on is performing incorrect operations on IPv6 addresses.

Example:

My IPv6 CIDR for the VPC:
So aws_vpc.ops-dev.ipv6_cidr_block = 2600:1f18:4704:1600::/56

The code in terraform:

in my subnet:
ipv6_cidr_block = "${cidrsubnet(aws_vpc.ops-dev.ipv6_cidr_block, 8, 0)}"

in my aws_instance:
ipv6_addresses = ["${cidrhost(aws_subnet.subnet-1.ipv6_cidr_block, 5)}"]

This is the computed value terraform attempts to instantiate - which obviously fails because its (way) outside the subnet CIDR.
ipv6_addresses.0: "2600:1f1d:4704:1600::"

This is completely wrong.

When applying the patch I submitted on the issue in the remote library:
apparentlymart/go-cidr#4

The correct IP address is specified:
ipv6_addresses.0: "2600:1f18:4704:1600::5"

This is a pretty high-profile issue as the function is presently completely incompatible with ipv6.

[apparentlymart]

Thanks for reporting this, and for submitting that fix to go-cidr, @mlosapio.

#15326 upgrades the vendored copy of the library to get your fix.

[apparentlymart]

Looks like I forgot to close this! This was merged and included in 0.10.0-beta1.

Thanks again, @mlosapio!

[ghost]

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