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Re: Operating Postfix with IPv6 (dual-stack)

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  • lst_hoe02@kwsoft.de
    ... Is the last point still on todo list or considered worth to be included in the future? Regards Andreas
    Message 1 of 12 , Feb 1, 2011
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      Zitat von Wietse Venema <wietse@...>:

      > lst_hoe02@...:
      >> Hello
      >>
      >> we are on the way to IPv6 and some question arise about Postfix IPv6
      >> behaviour in dual stack setup.
      >
      > You mean dual-protocol. Unlike some versions of Linux, there exist
      > systems that have a single unified TCP/IP stack implementation (the
      > protocols have a fair amount of behavior in common).
      >
      >> 1.) Do the lookups for AAAA when resolving MX records occur in
      >> parallel to A queries, or is some additional latency expected due to
      >> the fact that many AAAA queries fail by timeout and others resolving
      >> errors?
      >
      > With smtp_host_lookup=dns, all SMTP client lookups are sequential.
      > With smtp_host_lookup=native (or dns,native) Postfix in dual-protocol
      > mode will invoke getaddrinfo() with hints.ai_family=PF_UNSPEC.
      > The internals of getaddrinfo() are system dependent.
      >
      >> 2.) Do AAAA/ip6.arpa lookup occur on client connects from IPv4
      >> addresses or only when a client connects by IPv6 (name/reverse lookups)?
      >
      > The Postfix SMTP server's FCRDNS lookups use the getnameinfo() and
      > getaddrinfo() system library functions. In dual-protocol mode,
      > Postfix invokes getaddrinfo() with hints.ai_family=PF_UNSPEC; it
      > would be smarter to pass the client's address family instead.
      >
      > Wietse

      Is the last point still on todo list or considered worth to be
      included in the future?

      Regards

      Andreas
    • Wietse Venema
      ... It is not a high priority. Moreover, this means ripping up a low-level API, so it would take longer. I m still fixing code that was merged into Postfix 9
      Message 2 of 12 , Feb 1, 2011
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        lst_hoe02@...:
        > Zitat von Wietse Venema <wietse@...>:
        >
        > > lst_hoe02@...:
        > >> Hello
        > >>
        > >> we are on the way to IPv6 and some question arise about Postfix IPv6
        > >> behaviour in dual stack setup.
        > >
        > > You mean dual-protocol. Unlike some versions of Linux, there exist
        > > systems that have a single unified TCP/IP stack implementation (the
        > > protocols have a fair amount of behavior in common).
        > >
        > >> 1.) Do the lookups for AAAA when resolving MX records occur in
        > >> parallel to A queries, or is some additional latency expected due to
        > >> the fact that many AAAA queries fail by timeout and others resolving
        > >> errors?
        > >
        > > With smtp_host_lookup=dns, all SMTP client lookups are sequential.
        > > With smtp_host_lookup=native (or dns,native) Postfix in dual-protocol
        > > mode will invoke getaddrinfo() with hints.ai_family=PF_UNSPEC.
        > > The internals of getaddrinfo() are system dependent.
        > >
        > >> 2.) Do AAAA/ip6.arpa lookup occur on client connects from IPv4
        > >> addresses or only when a client connects by IPv6 (name/reverse lookups)?
        > >
        > > The Postfix SMTP server's FCRDNS lookups use the getnameinfo() and
        > > getaddrinfo() system library functions. In dual-protocol mode,
        > > Postfix invokes getaddrinfo() with hints.ai_family=PF_UNSPEC; it
        > > would be smarter to pass the client's address family instead.
        > >
        > > Wietse
        >
        > Is the last point still on todo list or considered worth to be
        > included in the future?

        It is not a high priority. Moreover, this means ripping up a
        low-level API, so it would take longer. I'm still fixing code
        that was merged into Postfix 9 years ago.

        Wietse
      • Wietse Venema
        ... Fixed. Grumble. Another to hours of analysis, implementation, test, documentation, and review. Wietse
        Message 3 of 12 , Feb 1, 2011
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          Wietse Venema:
          > > >> 2.) Do AAAA/ip6.arpa lookup occur on client connects from IPv4
          > > >> addresses or only when a client connects by IPv6 (name/reverse lookups)?
          > > >
          > > > The Postfix SMTP server's FCRDNS lookups use the getnameinfo() and
          > > > getaddrinfo() system library functions. In dual-protocol mode,
          > > > Postfix invokes getaddrinfo() with hints.ai_family=PF_UNSPEC; it
          > > > would be smarter to pass the client's address family instead.
          > > >
          > > > Wietse
          > >
          > > Is the last point still on todo list or considered worth to be
          > > included in the future?
          >
          > It is not a high priority. Moreover, this means ripping up a
          > low-level API, so it would take longer. I'm still fixing code
          > that was merged into Postfix 9 years ago.

          Fixed. Grumble. Another to hours of analysis, implementation, test,
          documentation, and review.

          Wietse
        • lst_hoe02@kwsoft.de
          ... Sorry, i did not want to bother you. My only intention was to prevent that something maybe valuable for performance might get lost. Many Thanks Andreas
          Message 4 of 12 , Feb 1, 2011
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            Zitat von Wietse Venema <wietse@...>:

            > Wietse Venema:
            >> > >> 2.) Do AAAA/ip6.arpa lookup occur on client connects from IPv4
            >> > >> addresses or only when a client connects by IPv6 (name/reverse
            >> lookups)?
            >> > >
            >> > > The Postfix SMTP server's FCRDNS lookups use the getnameinfo() and
            >> > > getaddrinfo() system library functions. In dual-protocol mode,
            >> > > Postfix invokes getaddrinfo() with hints.ai_family=PF_UNSPEC; it
            >> > > would be smarter to pass the client's address family instead.
            >> > >
            >> > > Wietse
            >> >
            >> > Is the last point still on todo list or considered worth to be
            >> > included in the future?
            >>
            >> It is not a high priority. Moreover, this means ripping up a
            >> low-level API, so it would take longer. I'm still fixing code
            >> that was merged into Postfix 9 years ago.
            >
            > Fixed. Grumble. Another to hours of analysis, implementation, test,
            > documentation, and review.
            >
            > Wietse

            Sorry, i did not want to bother you. My only intention was to prevent
            that something maybe valuable for performance might get lost.

            Many Thanks

            Andreas
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