[exim] Re: mysql_servers syntax for ipv6-only database serve…

> On Fri, Nov 15, 2024 at 12:05:29AM +0000, Jeremy Harris via Exim-users
> wrote:
>
> >   ipv6.port          (new, but note that dot)
>
> That dot feels unwise to me, much closer to established practice would
> be: [ipv6]:port.  Note that some IPv6 address have "."'s:
>
>     - ::ffff:192.0.2.1
>     - ::192.0.2.1
>
>

I'm not sure that ::ffff:192.0.2.1 will ever occur,as all the examples I
have seen indicate that the embedded IPv4 address has an immediately
preceding double colon.

But your point is valid.

RFC 6052 section 2.4 (https://www.rfc-editor.org/rfc/rfc6052#section-2.4),
I'm including it here so in case anyone here are unfamiliar with it.

2.4.  Text Representation

   IPv4-embedded IPv6 addresses will be represented in text in
   conformity with Section 2.2 of [RFC4291].  IPv4-embedded IPv6
   addresses constructed using the Well-Known Prefix or a /96 Network-
   Specific Prefix may be represented using the alternative form
   presented in Section 2.2 of [RFC4291], with the embedded IPv4 address
   represented in dotted decimal notation.  Examples of such
   representations are presented in Tables 1 and 2.

   +-----------------------+------------+------------------------------+
   | Network-Specific      |    IPv4    | IPv4-embedded IPv6 address   |
   | Prefix                |   address  |                              |
   +-----------------------+------------+------------------------------+
   | 2001:db8::/32         | 192.0.2.33 | 2001:db8:c000:221::          |
   | 2001:db8:100::/40     | 192.0.2.33 | 2001:db8:1c0:2:21::          |
   | 2001:db8:122::/48     | 192.0.2.33 | 2001:db8:122:c000:2:2100::   |
   | 2001:db8:122:300::/56 | 192.0.2.33 | 2001:db8:122:3c0:0:221::     |
   | 2001:db8:122:344::/64 | 192.0.2.33 | 2001:db8:122:344:c0:2:2100:: |
   | 2001:db8:122:344::/96 | 192.0.2.33 | 2001:db8:122:344::192.0.2.33 |
   +-----------------------+------------+------------------------------+

    Table 1: Text Representation of IPv4-Embedded IPv6 Addresses Using
                         Network-Specific Prefixes
     +-------------------+--------------+----------------------------+
     | Well-Known Prefix | IPv4 address | IPv4-Embedded IPv6 address |
     +-------------------+--------------+----------------------------+
     | 64:ff9b::/96      |  192.0.2.33  | 64:ff9b::192.0.2.33        |
     +-------------------+--------------+----------------------------+

    Table 2: Text Representation of IPv4-Embedded IPv6 Addresses Using
                           the Well-Known Prefix

   The Network-Specific Prefix examples in Table 1 are derived from the
   IPv6 prefix reserved for documentation in [RFC3849].  The IPv4
   address 192.0.2.33 is part of the subnet 192.0.2.0/24 reserved for
   documentation in [RFC5735].  The representation of IPv6 addresses is
   compatible with [RFC5952].

-- 
Jan