ListenAddress works the same as BindToAddress, except that from now on,
explicitly binding outgoing packets to the address of a socket is only done for
sockets specified with BindToAddress.
If the Port statement is not used, there are two other ways to let tinc listen
on a non-default port: either by specifying one or more BindToAddress
statements including port numbers, or by starting it from systemd with socket
activation. Tinc announces its own port to other nodes, but before it only
announced what was set using the Port statement.
The restriction of accepting only 1 connection per second from a single address
is a bit too much, especially if one wants to join a VPN using an invitation,
which requires two connections.
It now defers reading from stdin until after the authentication phase is
completed. Furthermore, it supports the -q, -r, -w options similar to those of
Jürgen Nickelsen's socket.
The tinc utility defered calling WSAStartup() until it tried to connect to a
running tinc daemon. However, socket functions are now also used for other
things (like joining another VPN using an invitation). Now we just
unconditionally call WSAStartup() early in main().
It seems like a lot of overhead to call access() for every possible extension
defined in PATHEXT, but apparently this is what Windows does itself too. At
least this avoids calling system() when the script one is looking for does not
exist at all.
Since the tinc utility also needs to call scripts, execute_script() is now
split off into its own source file.
Since filenames could potentially leak to unprivileged users (for example,
because of locatedb), it should not contain the cookie used for invitations.
Instead, tinc now uses the hash of the cookie and the invitation key as the
filename to store pending invitations in.
Commit cff5a84 removed the feature of binding outgoing TCP sockets to a local
address. We now call bind() again, but only if there is exactly one listening
socket with the same address family as the destination address of the outgoing
socket.
