Implement a basic connection tracking that counts the number of concurrent
connections when they open and close.
This commit also adds the circuit creation mitigation data structure that will
be needed at later commit to keep track of the circuit rate.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Using absolute_msec requires a 64-bit division operation every time
we calculate it, which gets expensive on 32-bit architectures.
Instead, just use the lazy "monotime_coarse_get()" operation, and
don't convert to milliseconds until we absolutely must.
In this case, it seemed fine to use a full monotime_coarse_t rather
than a truncated "stamp" as we did to solve this problem for the
timerstamps in buf_t and packed_cell_t: There are vastly more cells
and buffer chunks than there are channels, and using 16 bytes per
channel in the worst case is not a big deal.
There are still more millisecond operations here than strictly
necessary; let's see any divisions show up in profiles.
Couple things happen in this commit. First, we do not re-queue a cell back in
the circuit queue if the write packed cell failed. Currently, it is close to
impossible to have it failed but just in case, the channel is mark as closed
and we move on.
The second thing is that the channel_write_packed_cell() always took ownership
of the cell whatever the outcome. This means, on success or failure, it needs
to free it.
It turns out that that we were using the wrong free function in one case and
not freeing it in an other possible code path. So, this commit makes sure we
only free it in one place that is at the very end of
channel_write_packed_cell() which is the top layer of the channel abstraction.
This makes also channel_tls_write_packed_cell_method() return a negative value
on error.
Two unit tests had to be fixed (quite trivial) due to a double free of the
packed cell in the test since now we do free it in all cases correctly.
Part of #23709
Signed-off-by: David Goulet <dgoulet@torproject.org>
This removed code that was either never reached or irrelevant after the
incoming/outgoing queue removal such as the "timestamp_drained".
Lots of things are also removed from channel.h that do not exists anymore or
not used.
Signed-off-by: David Goulet <dgoulet@torproject.org>
The channel_write_cell() and channel_write_var_cell() can't be possibly called
nor are used by tor. We only write on the connection outbuf packed cell coming
from the scheduler that takes them from the circuit queue.
This makes channel_write_packed_cell() the only usable function. It is
simplify and now returns a code value. The reason for this is that in the next
commit(s), we'll re-queue the cell onto the circuit queue if the write fails.
Finally, channel unit tests are being removed with this commit because they do
not match the new semantic. They will be re-written in future commits.
Signed-off-by: David Goulet <dgoulet@torproject.org>
The channel subsystem was doing a whole lot to track and try to predict the
channel queue size but they are gone due to previous commit.
Signed-off-by: David Goulet <dgoulet@torproject.org>
For the rationale, see ticket #23709.
This is a pretty massive commit. Those queues were everywhere in channel.c and
it turns out that it was used by lots of dead code.
The channel subsystem *never* handles variable size cell (var_cell_t) or
unpacked cells (cell_t). The variable ones are only handled in channeltls and
outbound cells are always packed from the circuit queue so this commit removes
code related to variable and unpacked cells.
However, inbound cells are unpacked (cell_t), that is untouched and is handled
via channel_process_cell() function.
In order to make the commit compile, test have been modified but not passing
at this commit. Also, many tests have been removed but better improved ones
get added in future commits.
This commit also adds a XXX: which indicates that the handling process of
outbound cells isn't fully working. This as well is fixed in a future commit.
Finally, at this commit, more dead code remains, it will be cleanup in future
commits.
Fixes#23709
Signed-off-by: David Goulet <dgoulet@torproject.org>
- HT_FOREACH_FN defined in an additional place because nickm did that
in an old kist prototype
- Make channel_more_to_flush mockable for future sched tests
- Add empty scheduler_{vanilla,kist}.c files and put in include.am
Signed-off-by: David Goulet <dgoulet@torproject.org>
This patch replaces a few calls to router_get_by_id_digest ("do we
have a routerinfo?") with connection_or_digest_is_known_relay ("do
we know this relay to be in the consensus, or have been there some
time recently?").
Found while doing the 21585 audit; fixes bug 23533. Bugfix on
0.3.0.1-alpha.
Accomplished via the following:
1. Use NETINFO cells to determine if both peers will agree on canonical
status. Prefer connections where they agree to those where they do not.
2. Alter channel_is_better() to prefer older orconns in the case of multiple
canonical connections, and use the orconn with more circuits on it in case
of age ties.
Also perform some hourly accounting on how many of these types of connections
there are and log it at info or notice level.
This defense will cause Cisco, Juniper, Fortinet, and other routers operating
in the default configuration to collapse netflow records that would normally
be split due to the 15 second flow idle timeout.
Collapsing these records should greatly reduce the utility of default netflow
data for correlation attacks, since all client-side records should become 30
minute chunks of total bytes sent/received, rather than creating multiple
separate records for every webpage load/ssh command interaction/XMPP chat/whatever
else happens to be inactive for more than 15 seconds.
The defense adds consensus parameters to govern the range of timeout values
for sending padding packets, as well as for keeping connections open.
The defense only sends padding when connections are otherwise inactive, and it
does not pad connections used solely for directory traffic at all. By default
it also doesn't pad inter-relay connections.
Statistics on the total padding in the last 24 hours are exported to the
extra-info descriptors.
We switched these to be "if (1) " a while back, so we could keep
the indentation and avoid merge conflicts. But it's nice to clean
up from time to time.
