[Xapian-tickets] [Xapian] #374: IPv6 support

[Xapian]

#374: IPv6 support
----------------------------+------------------------------
 Reporter:  olly            |             Owner:  olly
     Type:  defect          |            Status:  assigned
 Priority:  low             |         Milestone:  1.3.3
Component:  Backend-Remote  |           Version:  SVN trunk
 Severity:  normal          |        Resolution:
 Keywords:                  |        Blocked By:
 Blocking:                  |  Operating System:  All
----------------------------+------------------------------
Changes (by olly):

 * status:  new => assigned
 * milestone:  1.3.x => 1.3.3


Comment:

 I've been looking into this some more.

 The Linux gethostbyname(3) man page says:

 > gethostbyname(),  gethostbyaddr(), and h_errno are marked obsolescent in
 [the POSIX.1-2001] standard.
 > POSIX.1-2008 removes the specifications of gethostbyname(),
 gethostbyaddr(), and h_errno, recommending the use of getaddrinfo(3) and
 getnameinfo(3) instead.

 And the getaddrinfo(3) man page notes that this is specified by
 POSIX.1-2001.

 Given this was standardised 13 years ago and is the standard way to
 support IPv6, it seems hard to conceive that there are relevant systems
 without getaddrinfo() at this point.

 The Gnulib docs note about getaddrinfo():

 > This function is missing on some platforms: HP-UX 11.11, IRIX 6.5, OSF/1
 5.1, Solaris 7, Cygwin 1.5.x, mingw, MSVC 9, Interix 3.5, BeOS.

 https://www.gnu.org/software/gnulib/manual/html_node/getaddrinfo.html

 Looking up the versions on that list, they're all out of support - often
 by many years.

 It's unclear to me if MSVC 9 is in support or not, but it's irrelevant as
 we decided to require C++11 support for 1.3.x and up.  As for OS versions,
 MSDN seems to indicate that getaddrinfo() was added in XP.

 Checking the headers of the MXE install on the buildbot vm, that has
 getaddrinfo().

 So I'd say we don't try to fall back to gethostbyname() - it's just going
 to complicate the code and probably for no reason.  If there are really
 relevant systems with a C++11 compiler and without getaddrinfo(), we can
 look at supporting them (and in that case, Gnulib's approach of a
 compatibility implementation of getaddrinfo() which calls gethostbyname()
 under the covers seems a reasonable approach).

 Another benefit of this change is that getaddrinfo() is thread-safe, while
 gethostbyname() isn't.

 > Incidentally, getaddrinfo() has the added benefit of resolving service
 names as well as numeric ports. This suggests that the API of !TcpServer
 needs to change to accommodate this.

 I don't think we need to worry about named ports - it doesn't make much
 sense to run a xapian-tcpsrv on a port reserved for another protocol,
 which is what that would allow, so I suggest we just set the
 {{{AI_NUMERICSERV}}} flag.

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Ticket URL: <http://trac.xapian.org/ticket/374#comment:7>
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