[RFC PATCH 00/31] secnet: Transport over IPv6

[Ian Jackson]

This is my main outstanding branch.  With this, I am able to exchange
IPv4 on the inside network over UDP/IPv6 on the outside, at least in a
simple test setup.

I don't intend to push this to master any time soon.  For now, I'm
posting it for comment, while I test it and develop the polypath
support which is going to come next.

 01/31 subnet_to_string: Do not allocate
 02/31 site: transport peers: Formalise interface to transport peers
 03/31 site: transport peers: Notes on multi-address-family (IPv6) support
 04/31 comm_if: Define the meaning of ->sendmsg returning false
 05/31 site: transport peers: Delete or demote unsuitable peers addresses
 06/31 site: Make transport_record_peers cope with multiple addresses
 07/31 site: transport peers: Update bulk of code for multiple addresses
 08/31 resolver: construct comm_addr; honour multiple addresses from ...
 09/31 site: Permit multiple peer addresses even if peer is static
 10/31 site: Remove "wishful thinking" from transport address handling comment
 11/31 ipv6: introduce union iaddr
 12/31 ipv6: More buffers in iaddr_to_string
 13/31 autoconf: Update to autoconf 2.69
 14/31 ipv6: check for support in system and in adns
 15/31 ipv6: Support printing, comparing, etc. IPv6 addresses
 16/31 udp proxy: Properly zero holes in proxied address
 17/31 udp: Break out udp_make_socket
 18/31 Make list_length and string_item_to_ipaddr const-correct.
 19/31 Provide ARRAY_SIZE
 20/31 Provide text2iaddr.
 21/31 udp.c: Remove some (ab)use of variable name `i'
 22/31 udp: Support IPv6 (mostly)
 23/31 udp: Support IPv6 when using authbind
 24/31 resolver: Support IPv6 name resolution
 25/31 resolver: Log reason for DNS resolution failure
 26/31 resolver: Support IPv6 literals
 27/31 Python IP addresses: Provide ipaddrset.py library
 28/31 Python IP addresses: Use modern ipaddr.py - supports IPv6
 29/31 Python IP addresses: Check for and maybe delete stale ipaddr.py
 30/31 Python IP addresses: Remove sys.path hacking from test script
 31/31 test-example: Switch to testing IPv6 too