Reg must constraint

YANG
1

Hi,
we need to define a constraint like, if the destination is v4, then next-hop should not be v6 vice versa.

In the must constraint, can we give the typedef name for the string pattern to be matched ? what i am looking for is, definitions of (regex for ) ipv4-address/prefix(same with v6) are present in type defed. can we use these directly or need to repeat every occurrence in the must.

Thanks
Phani

2

No, you can’t use a must expression that would verify the actual type used in a union-typed leaf. But in your case you do not have to use the full ipv4/ipv6 regex expressions; I think simple check for ":" in the IP address string is enough to determine the type (unless I’m wrong, every IPv6 address contains colon, no IPv4 address contains colon). Would that work for you?

3

Hi Mvf,
Thanks for the reply. I tried to use : or . character to differentiate these. But, i could not get the reg ex to match , contains this character . As it needs a full expression. Do you have any suggestion with : or .

Thanks
Phani

4

No regular expressions needed, I meant something like this:

  leaf destination {
    type inet:ip-address;
  }
  leaf next-hop {
    type inet:ip-address;
    must "contains(., ':') or not(contains(../destination, ':'))" {
      error-message "IPv6 address must be used as next-hop";
    }
    must "not(contains(., ':')) or contains(../destination, ':')" {
      error-message "IPv4 address must be used as next-hop";
    }
  }

This makes sure that if destination is IPv6 address, so must be next-hop, and vice versa.