Unable to get IPv6 with prefix from Framed-IPv6-Prefix attribute

[dav-komarek]

Description

When packet containing following bytes is parsed 61 0a 00 40 20 01 15 30 10 0e using rfc3162.FramedIPv6Prefix_Get, the error is returned in the inner function radius.IPv6Prefix on the line https://github.com/layeh/radius/blob/master/attribute.go#L471. But the provided IPv6 is valid address (2001:1530:100e::/64)

Proposal

The function radius.IPv6Prefix should be able to parse IPv6 of the specified format.

Apparently the check for the length of the byte array (linked) is wrong and should be replaced with check that the prefix is at most 128 bits long.

[u873838]

Should be fixed with 1006025.

[dav-komarek]

Please check 1006025#r134862652.

[jamiesun]

Follow-up: #119 reported that the fix here rejects prefixes whose bits beyond the Prefix-Length are non-zero. #141 addresses that by clearing those bits on decode rather than erroring, while keeping this issue's tolerance for omitted trailing zero bytes.