Since we now open sockets for each address family independently (via
IPV6_V6ONLY) and without SO_REUSEADDR, it could happen with the previous
order on Linux that opening the port that was allocated as ephemeral
port for IPv6 was already used by a different process for IPv4.
Most IPv6 sockets on ephemeral ports will not have IPV6_V6ONLY set, so
the same port is also reserved for IPv4. Therefore, it's save to assume
that any ephemeral port we first get for IPv4 is free for IPv6.
References strongswan/strongswan#2494
Otherwise, we can't open a dedicated IPv4 socket on the same port as the
IPv6 socket already is set up do receive IPv4 packets (unless we'd again
enable SO_REUSEADDR).
Fixes: 83da133712 ("socket-default: Don't set SO_REUSEADDR on IKE sockets anymore")
This was originally required when pluto and charon both bound sockets to
the same port to send messages. Pluto also received messages on them but
charon didn't and used a raw socket instead. Since the removal of pluto
we don't need to set this option anymore, which might actually mask
mistakes like running charon and charon-systemd concurrently (that could
result in messages getting sent fine by both daemons but only received
by one).
Note that a failure to create/bind the sockets will not immediately
result in a shutdown of the daemon. Instead, there will be an error
once the receiver tries to read any messages and also whenever the sender
attempts to send a request.
%unique (and the upcoming %same key) are usable in specific contexts only.
To restrict the user from using it in other places where it does not get the
expected results, reject such keywords unless explicitly allowed.
On Linux, setting the source address is insufficient to force a packet to be
sent over a certain path. The kernel uses the best route to select the outgoing
interface, even if we set a source address of a lower priority interface. This
is not only true for interfaces attaching to the same subnet, but also for
unrelated interfaces; the kernel (at least on 4.7) sends out the packet on
whatever interface it sees fit, even if that network does not expect packets
from the source address we force to.
When a better interface becomes available, strongSwan sends its MOBIKE address
list update using the old source address. But the kernel sends that packet over
the new best interface. If that network drops packets having the unexpected
source address from the old path, the MOBIKE update fails and the SA finally
times out.
To enforce a specific interface for our packet, we explicitly set the interface
index from the interface where the source address is installed. According to
ip(7), this overrules the specified source address to the primary interface
address. As this could have side effects to installations using multiple
addresses on a single interface, we disable the option by default for now.
This also allows using IPv6 link-local addresses, which won't work if
the outbound interface is not set explicitly.
This ensures we don't pass data (via msg_control) defined in a different
scope to sendmsg(). Actually, some compilers (e.g. GCC 5.2.1) might
optimize the memcpy() call away causing the packets not to get sent from
the intended source address.
It also makes the code clearer than with all these ifdefs.
Fixes#1171.
If multiple sockets are ready, we previously preferred the IPv4 non-NAT socket
over others. To handle all with equal priority, use a round-robin selection.
INCLUDES are now deprecated and throw warnings when using automake 1.13.
We now also differentiate AM_CPPFLAGS and AM_CFLAGS, where includes and
defines are passed to AM_CPPFLAGS only.
It seems that the order of binding sockets of different address families to the
same dynamic port must be v6-before-v4 on Linux, but v4-before-v6 on OS X.
Since the 3.5 Linux kernel both UDP implementations have a separate static
flag to indicate whether ANY sockets enabled UDP decapsulation.
As we only ever enabled it for one address family (in earlier versions IPv4
only, now for IPv6, if supported, and for IPv4 otherwise) UDP decapsulation
wouldn't work anymore (at least for one address family).
Tobias Brunner