ipv4 format checker is too lenient

[exarkun]

According to http://json-schema.org/latest/json-schema-validation.html#anchor117 the ipv4 format is an IPv4 address according to the "dotted-quad" ABNF syntax as defined in RFC 2673, section 3.2 [RFC2673].

The "dotted-quad" ABNF syntax referenced is:

dotted-quad      =  decbyte "." decbyte "." decbyte "." decbyte
decbyte          =  1*3DIGIT

The draft4_format_checker incorrectly allows the following values which do not conform to this syntax:

• 127.0
• 0x7f000001
• 2130706433
• 017700000001

Presumably according to the whims of the platform inet_aton implementation.

[Julian]

Hey,

Yup, thanks, good catch. Guess it's regex time.

Should be fairly simple, I can probably knock it off certainly before the next release. If you had interest yourself, the way to do that is to add a test to https://github.com/json-schema/JSON-Schema-Test-Suite/blob/develop/tests/draft4/optional/format.json#L61-L77 (which is git subtree'd into this repo).

[exarkun]

Thanks!