registration with invalid allowfrom fails open

[cpu]

I didn't read the documentation very carefully and thought I could POST /registration with an allowfrom entry for a single host address instead of a CIDR range, e.g.:

{
    "allowfrom": [
        "127.0.0.1"
    ]
}

acme-dns filters this invalid allowfrom in acmedb.Register using cidrslice.ValidEntries. The registration is created successfully with no errors, but the returned allowfrom is empty and so is the field in the database for this user:

{
  "username": "<rand>",
  "password": "<rand>",
  "fulldomain": "<rand>.example.com",
  "subdomain": "<rand>",
  "allowfrom": []
}

The documentation specifically says to use a CIDR range but I think there might be a case to be made for rejecting the registration with an error when the allowfrom contains invalid entries. Since allowfrom is a security control I think acme-dns should be conservative and fail fast when it can't fulfill the request as received.

@joohoi What do you think?

[joohoi]

I think you are on the right track here, and we should fail early. But from the UX perspective, I think what would be best way to handle this, would be to automatically add /32 bitmask if none is specified but the IP address itself is valid.

[cpu]

from the UX perspective, I think what would be best way to handle this, would be to automatically add /32 bitmask if none is specified but the IP address itself is valid.

That sounds like a nice compromise 👍

[joohoi]

This is now finally fixed. I opted to not to introduce magic I proposed in #43 (comment) . The only magic is removing [ and ] from the IP addresses as the net.ParseCIDR cannot handle that notation of IPv6 addresses.