This is all a matter of context - The IP address of 0.0.0.0 is indeed valid if dealing with network routes.
Furthermore, the aspect of leading zeros is also contextual as an IP address is a 32-bit binary number, the dotted-quad merely a representation of this - It could be rightly argued that the leading zeros are nothing more than another representation of an IP address.
See ybiC's Don't Use Regular Expressions To Parse IP Addresses! for an excellent treatise on this topic.
perl -le 'print+unpack("N",pack("B32","00000000000000000000001000000111"))' | [reply]
[d/l] |
Granted, 0.0.0.0 is technically a valid IP address in some situations, as in dealing with network routes, but for most situations it would be considered as something out of the ordinary, which is why I initially mentioned it.
Also, leading zeros, while also technically valid, are also usually not what one would consider a proper IP address.
If you say ping 065.1.01.002, you are probably not going to ping what you think you are pinging.
(at least if you are trying to ping 65.1.1.2).
As you rightly said though, this is all a matter of context.:-). You must know your data before trying to implement any solution.
While using a regex for mild IP sanity checking may be ok in some situations,
I do agree though that as a rule, regexes should NOT be used parse IP addresses, as ybiC's excelent article states.
Best Regards,
Wonko
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