Besides controlling when tinc-up and tinc-down get called, this commit makes
DeviceStandby control when the virtual network interface "cable" is "plugged"
on Windows. This is more user-friendly as the status of the tinc network can
be seen just by looking at the state of the network interface, and it makes
Windows behave better when isolated.
This adds a new DeviceStandby option; when it is disabled (the default),
behavior is unchanged. If it is enabled, tinc-up will not be called during
tinc initialization, but will instead be deferred until the first node is
reachable, and it will be closed as soon as no nodes are reachable.
This is useful because it means the device won't be set up until we are fairly
sure there is something listening on the other side. This is more user-friendly,
as one can check on the status of the tinc network connection just by checking
the status of the network interface. Besides, it prevents the OS from thinking
it is connected to some network when it is in fact completely isolated.
In send_sptps_data(), the len variable contains the length of the whole
datagram that needs to be sent to the peer, including the overhead from SPTPS
itself.
When tinc runs the graph algorithms and updates the nexthop and via pointers,
it uses a breadth-first search, but it can sometimes revisit nodes that have
already been visited if the previous path is marked as being indirect, and
there is a longer path that is "direct". The via pointer should be updated in
this case, because this points to the closest hop to the destination that can
be reached directly. However, the nexthop pointer should not be updated.
This fixes a bug where there could potentially be a routing loop if a node in
the graph has an edge with the indirect flag set, and some other edge without
that flag, the indirect edge is part of the minimum spanning tree, and a
broadcast packet is being sent.
The main reason to switch from AES-256-GCM to ChaCha-Poly1305 is to remove a
dependency on OpenSSL, whose behaviour of the AES-256-GCM decryption function
changes between versions. The source code for ChaCha-Pol1305 is small and in
the public domain, and can therefore be easily included in tinc itself.
Moreover, it is very fast even without using any optimized assembler, easily
outperforming AES-256-GCM on platforms that don't have special AES instructions
in hardware.
This uses the portable Ed25519 library made by Orson Peters, which in turn uses
the reference implementation made by Daniel J. Bernstein.
This implementation also allows Ed25519 keys to be used for key exchange, so
there is no need to add a separate implementation of Curve25519.
- Try to prevent SIGPIPE from being sent for errors sending to the control
socket. We don't outright block the SIGPIPE signal because we still want the
tinc CLI to exit when its output is actually sent to a real (broken) pipe.
- Don't call exit() from top(), and properly detect when the control socket is
closed by the tincd.
Before, the tapreader thread would just exit immediately after encountering the
first error, without notifying the main thread. Now, the tapreader thead never
exits itself, but tells the main thread to stop when more than ten errors are
encountered in a row.
Before, when making a meta-connection to a node (either because of a ConnectTo
or because AutoConnect is set), tinc required one or more Address statements
in the corresponding host config file. However, tinc learns addresses from
other nodes that it uses for UDP connections. We can use those just as well for
TCP connections.
When creating invitations or using them to join a VPN, and the tinc command is
not run interactively (ie, when stdin and stdout are not connected or
redirected to/from a file), don't ask questions. If normally tinc would ask for
a confirmation, just assume the default answer instead. If tinc really needs
some input, just print an error message instead.
In case an invitation is used for a VPN which uses a netname that is already in
use on the local host, tinc will store the configuration in a temporary
directory. Normally it asks for an alternative netname and then renames the
temporary directory, but when not run interactively, it now just prints the
location of the unchanged temporary directory.
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.
