PTs expect the auth cookie to be available immedieately after launch,
leading to a race condition when PTs opt to cache the extorport cookie
once immediately after startup.
Fixes#15240.
Parse the file just before voting and apply its information to the
provided vote_routerstatus_t. This follows the same logic as when
dirauths parse bwauth files.
The issue is that we use the cpuworker system with relays only, so if we
start up as a client and transition to being a relay later, we'll be
sad.
This fixes bug 14901; not in any released version of Tor.
It's now possible to use SocksPort or any other kind of port that can use a
Unix socket like so:
SocksPort unix:/foo/bar/unix.sock
Fixes#14451
Signed-off-by: David Goulet <dgoulet@ev0ke.net>
This incidentally makes unix SocksSocket support all the same options
as SocksPort.
This patch breaks 'SocksSocket 0'; next will restore it.
Resolves 14254.
If running under systemd, notify the supervisor about current PID
of Tor daemon. This makes systemd unit simpler and more robust:
it will do the right thing regardless of RunAsDaemon settings.
TestingDirAuthVoteHSDir ensures that authorities vote the HSDir flag
for the listed relays regardless of uptime or ORPort connectivity.
Respects the value of VoteOnHidServDirectoriesV2.
Partial fix for bug 14067.
If we're not a relay, we ignore it.
If it's set to 1, we obey ExitPolicy.
If it's set to 0, we force ExitPolicy to 'reject *:*'
And if it's set to auto, then we warn the user if they're running an
exit, and tell them how they can stop running an exit if they didn't
mean to do that.
Fixes ticket 10067
We had a check to block these, but the patch we merged as a1c1fc72
broke this check by making them absolute on demand every time we
opened them. That's not so great though. Instead, we should make them
absolute on startup, and not let them change after that.
Fixes bug 13397; bugfix on 0.2.3.11-alpha.
This happened because we changed AutomapHostsSuffixes to replace "."
with "", since a suffix of "" means "match everything." But our
option handling code for CSV options likes to remove empty entries
when it re-parses stuff.
Instead, let "." remain ".", and treat it specially when we're
checking for a match.
Fixes bug 12509; bugfix on 0.2.0.1-alpha.
This allows hidden services to disable the anti-scanning feature
introduced in 0.2.6.2-alpha. With this option not set, a connection
to an unlisted port closes the circuit. With this option set, only
a RELAY_DONE cell is sent.
Closes ticket #14084.
Decrease minimum consensus interval to 10 seconds
when TestingTorNetwork is set. (Or 5 seconds for
the first consensus.)
Fix code that assumes larger interval values.
This assists in quickly bootstrapping a testing
Tor network.
Fixes bugs 13718 & 13823.
The two statistics are:
1. number of RELAY cells observed on successfully established
rendezvous circuits; and
2. number of .onion addresses observed as hidden-service
directory.
Both statistics are accumulated over 24 hours, obfuscated by rounding
up to the next multiple of a given number and adding random noise,
and written to local file stats/hidserv-stats.
Notably, no statistics will be gathered on clients or services, but
only on relays.
1) Set them to the values that (according to Rob) avoided performance
regressions. This means that the scheduler won't get much exercise
until we implement KIST or something like it.
2) Rename the options to end with a __, since I think they might be
going away, and nobody should mess with them.
3) Use the correct types for the option variables. MEMUNIT needs to be a
uint64_t; UINT needs to be (I know, I know!) an int.
4) Validate the values in options_validate(); do the switch in
options_act(). This way, setting the option to an invalid value on
a running Tor will get backed out.
We add a compression level argument to tor_zlib_new, and use it to
determine how much memory to allocate for the zlib object. We use the
existing level by default, but shift to smaller levels for small
requests when we have been over 3/4 of our memory usage in the past
half-hour.
Closes ticket 11791.
Instead, generate new keys, and overwrite the empty key files.
Adds FN_EMPTY to file_status_t and file_status.
Fixes bug 13111.
Related changes due to review of FN_FILE usage:
Stop generating a fresh .old RSA key file when the .old file is missing.
Avoid overwriting .old key files with empty key files.
Skip loading zero-length extra info store, router store, stats, state,
and key files.
Document usage of the NO_DIRINFO and ALL_DIRINFO flags clearly in functions
which take them as arguments. Replace 0 with NO_DIRINFO in a function call
for clarity.
Seeks to prevent future issues like 13163.
Stop using the default authorities in networks which provide both
AlternateDirAuthority and AlternateBridgeAuthority.
This bug occurred due to an ambiguity around the use of NO_DIRINFO.
(Does it mean "any" or "none"?)
Partially fixes bug 13163.
Add the TestingDirAuthVoteExit option, a list of nodes to vote Exit for,
regardless of their uptime, bandwidth, or exit policy.
TestingTorNetwork must be set for this option to have any effect.
Works around an issue where authorities would take up to 35 minutes to
give nodes the Exit flag in a test network, despite short consensus
intervals. Partially implements ticket 13161.
Otherwise, when we authority try to do a self-test because of
init-keys, if that self-test can't be launched for whatever reason and
so we close the channel immediately, we crash.
Yes, this a silly way for initialization to work.
When DisableNetwork is set, do not launch pluggable transport plugins,
and if any are running already, terminate the existing instances.
Resolves ticket 13213.
Stop modifying the value of our DirReqStatistics torrc option just
because we're not a bridge or relay. This bug was causing Tor
Browser users to write "DirReqStatistics 0" in their torrc files
as if they had chosen to change the config.
Fixes bug 4244; bugfix on 0.2.3.1-alpha.
Tor Browser includes several ClientTransportPlugin lines in its
torrc-defaults file, leading every Tor Browser user who looks at her
logs to see these notices and wonder if they're dangerous.
Resolves bug 13124; bugfix on 0.2.5.3-alpha.
(And replay them once we know our first real logs.)
This is an implementation for issue 6938. It solves the problem of
early log mesages not getting sent to log files, but not the issue of
early log messages not getting sent to controllers.
This implements the meat of #12899. This commit should simply remove the
parts of Tor dirauths used to check whether a relay was supposed to be
named or not, it doesn't yet convert to a new mechanism for
reject/invalid/baddir/badexiting relays.
This is in preparation for a big patch series removing the entire Naming
system from Tor. In its wake, the approved-routers file is being
deprecated, and a replacement option to allow only pre-approved routers
is not being implemented.
The fix for bug 4647 accidentally removed our hack from bug 586 that
rewrote HashedControlPassword to __HashedControlSessionPassword when
it appears on the commandline (which allowed the user to set her own
HashedControlPassword in the torrc file while the controller generates
a fresh session password for each run).
Fixes bug 12948; bugfix on 0.2.5.1-alpha.
This will fix the warning
"/src/or/config.c:6854:48: error: unused parameter 'group_readable'"
that I introduced while fixing 12864.
Bug not in any released version of Tor.
When we merged the cookieauthfile creation logic in 33c3e60a37, we
accidentally took out this feature. Fixes bug 12864, bugfix on
0.2.5.1-alpha.
Also adds an ExtORPortCookieAuthFileGroupReadable, since there's no
reason not to.
Authorities now assign the Guard flag to the fastest 25% of the
network (it used to be the fastest 50%). Also raise the consensus
weight that guarantees the Guard flag from 250 to 2000. For the
current network, this results in about 1100 guards, down from 2500.
This step paves the way for moving the number of entry guards
down to 1 (proposal 236) while still providing reasonable expected
performance for most users.
Implements ticket 12690.
Otherwise, it always seems as though our Exclude* options have
changed, since we're comparing modified to unmodified values.
Patch from qwerty1. Fixes bug 9801. Bugfix on 0.2.4.10-alpha, where
GeoIPExcludeUnknown was introduced.
This change allows using Socks4Proxy, Socks5Proxy and HTTPSProxy with
ClientTransportPlugins via the TOR_PT_PROXY extension to the
pluggable transport specification.
This fixes bug #8402.
None of the things we might exec() can possibly run under the
sanbox, so rather than crash later, we have to refuse to accept the
configuration nice and early.
The longer-term solution is to have an exec() helper, but wow is
that risky.
fixes 12043; bugfix on 0.2.5.1-alpha
on #9686, gmorehose reports that the 500 MB lower limit is too high
for raspberry pi users.
This is a backport of 647248729f to 0.2.4.
Note that in 0.2.4, the option is called MaxMemInCellQueues.
If we can't detect the physical memory, the new default is 8 GB on
64-bit architectures, and 1 GB on 32-bit architectures.
If we *can* detect the physical memory, the new default is
CLAMP(256 MB, phys_mem * 0.75, MAX_DFLT)
where MAX_DFLT is 8 GB on 64-bit architectures and 2 GB on 32-bit
architectures.
You can still override the default by hand. The logic here is simply
trying to choose a lower default value on systems with less than 12 GB
of physical RAM.
This means that tor can run without needing to communicate with ioctls
to the firewall, and therefore doesn't need to run with privileges to
open the /dev/pf device node.
A new TransProxyType is added for this purpose, "pf-divert"; if the user
specifies this TransProxyType in their torrc, then the pf device node is
never opened and the connection destination is determined with getsockname
(as per pf(4)). The default behaviour (ie., when TransProxyType is "default"
when using the pf firewall) is still to assume that pf is configured with
rdr-to rules.
This isn't on by default; to get it, you need to set "TransProxyType
ipfw". (The original patch had automatic detection for whether
/dev/pf is present and openable, but that seems marginally fragile.)
(If we don't restrict rename, there's not much point in restricting
open, since an attacker could always use rename to make us open
whatever they want.)
A new set of unit test cases are provided, as well as introducing
an alternative paradigm and macros to support it. Primarily, each test
case is given its own namespace, in order to isolate tests from each
other. We do this by in the usual fashion, by appending module and
submodule names to our symbols. New macros assist by reducing friction
for this and other tasks, like overriding a function in the global
namespace with one in the current namespace, or declaring integer
variables to assist tracking how many times a mock has been called.
A set of tests for a small-scale module has been included in this
commit, in order to highlight how the paradigm can be used. This
suite gives 100% coverage to status.c in test execution.
By default, after you've made a connection to port XYZ, we assume
you might still want to have an exit ready to connect to XYZ for one
hour. This patch lets you lower that interval.
Implements ticket 91
We log only one message, containing a complete list of what's
wrong. We log the complete list whenever any of the possible things
that could have gotten wrong gets worse.
Fix for #9870. Bugfix on 10480dff01, which we merged in
0.2.5.1-alpha.
These options were added back in 0.1.2.5-alpha, but no longer make any
sense now that all directories support tunneled connections and
BEGIN_DIR cells. These options were on by default; now they are
always-on.
This is a fix for 10849, where TunnelDirConns 0 would break hidden
services -- and that bug arrived, I think, in 0.2.0.10-alpha.
(There is no longer meaningfully any such thing as a HS authority,
since we stopped uploading or downloading v0 hs descriptors in
0.2.2.1-alpha.)
Implements #10881, and part of #10841.
I'm doing this because:
* User doesn't mean you're running as root, and running as root
doesn't mean you've set User.
* It's possible that the user has done some other
capability-based hack to retain the necessary privileges.
The remaining vestige is that we continue to publish the V2dir flag,
and that, for the controller, we continue to emit v2 directory
formats when requested.
In 0.2.3.8-alpha we attempted to "completely disable stats if we aren't
running as a relay", but instead disabled them only if we aren't running
as a server.
This commit leaves DirReqStatistics enabled on both relays and bridges,
and disables (Cell,Entry,ExitPort)Statistics on bridges.
We had accidentially grown two fake ones: one for backtrace.c, and one
for sandbox.c. Let's do this properly instead.
Now, when we configure logs, we keep track of fds that should get told
about bad stuff happening from signal handlers. There's another entry
point for these that avoids using non-signal-handler-safe functions.
On platforms with the backtrace/backtrace_symbols_fd interface, Tor
can now dump stack traces on assertion failure. By default, I log
them to DataDir/stack_dump and to stderr.
For now, round down to the nearest 10 minutes. Later, eliminate entirely by
setting a consensus parameter.
(This rounding is safe because, in 0.2.2, where the timestamp mattered,
REND_REPLAY_TIME_INTERVAL was a nice generous 60 minutes.)
Whenever we had an non-option commandline arguments *and*
option-bearing commandline arguments on the commandline, we would save
only the latter across invocations of options_init_from_torrc, but
take their existence as license not to re-parse the former. Yuck!
Incidentally, this fix lets us throw away the backup_arg[gv] logic.
Fix for bug 9746; bugfix on d98dfb3746,
not in any released Tor. Found by Damian. Thanks, Damian!
This just goes to show: never cast a function pointer. Found while
testing new command line parse logic.
Bugfix on 1293835440, which implemented
6752: Not in any released tor.
Use the generic function for both the ControlPort cookie and the
ExtORPort cookie.
Also, place the global cookie variables in the heap so that we can
pass them around more easily as pointers.
Also also, fix the unit tests that broke by this change.
Conflicts:
src/or/config.h
src/or/ext_orport.c
I added this so I could write a unit test for ServerTransportOptions,
but it incidentally exercises the succeed-on-defaults case of
options_validate too.
We previously used FILENAME_PRIVATE identifiers mostly for
identifiers exposed only to the unit tests... but also for
identifiers exposed to the benchmarker, and sometimes for
identifiers exposed to a similar module, and occasionally for no
really good reason at all.
Now, we use FILENAME_PRIVATE identifiers for identifiers shared by
Tor and the unit tests. They should be defined static when we
aren't building the unit test, and globally visible otherwise. (The
STATIC macro will keep us honest here.)
For identifiers used only by the unit tests and never by Tor at all,
on the other hand, we wrap them in #ifdef TOR_UNIT_TESTS.
This is not the motivating use case for the split test/non-test
build system; it's just a test example to see how it works, and to
take a chance to clean up the code a little.
This implements "algorithm 1" from my discussion of bug #9072: on OOM,
find the circuits with the longest queues, and kill them. It's also a
fix for #9063 -- without the side-effects of bug #9072.
The memory bounds aren't perfect here, and you need to be sure to
allow some slack for the rest of Tor's usage.
This isn't a perfect fix; the rest of the solutions I describe on
codeable.
A new option TestingV3AuthVotingStartOffset is added which offsets the
starting time of the voting interval. This is possible only when
TestingTorNetwork is set.
This patch makes run_scheduled_events() check for new consensus
downloads every second when TestingTorNetwork, instead of every
minute. This should be fine, see #8532 for reasoning.
This patch also brings MIN_VOTE_SECONDS and MIN_DIST_SECONDS down from
20 to 2 seconds, unconditionally. This makes sanity checking of
misconfiguration slightly less sane.
Addresses #8532.
You can't use != to compare arbitary members of or_options_t.
(Also, generate a better error message to say which Testing* option
was set.)
Fix for bug 8992. Bugfix on b0d4ca49. Bug not in any released Tor.
- Avoid control_event_refill_global function with 13 arguments and
increase code reuse factor by moving more code from control.c to
connection.c.
- Avoid an unsafe uint32_t -> int cast.
- Add TestingEnableTbEmptyEvent option.
- Prepare functions for testing.
- Rename a few functions and improve documentation.
- Move cell_command_to_string from control.c to command.c.
- Use accessor for global_circuitlist instead of extern.
- Add a struct for cell statistics by command instead of six arrays.
- Split up control_event_circuit_cell_stats by using two helper functions.
- Add TestingEnableCellStatsEvent option.
- Prepare functions for testing.
- Rename a few variables and document a few things better.
Create new methods check_or_create_data_subdir() and
write_to_data_subdir() in config.c and use them throughout
rephist.c and geoip.c.
This should solve ticket #4282.
I have no idea whether b0rken clients will DoS the network if the v2
authorities all turn this on or not. It's experimental. See #6783 for
a description of how to test it more or less safely, and please be
careful!
It returns the method by which we decided our public IP address
(explicitly configured, resolved from explicit hostname, guessed from
interfaces, learned by gethostname).
Now we can provide more helpful log messages when a relay guesses its IP
address incorrectly (e.g. due to unexpected lines in /etc/hosts). Resolves
ticket 2267.
While we're at it, stop sending a stray "(null)" in some cases for the
server status "EXTERNAL_ADDRESS" controller event. Resolves bug 8200.
- Document the key=value format.
- Constify equal_sign_pos.
- Pass some strings that are about to be logged to escape().
- Update documentation and fix some bugs in tor_escape_str_for_socks_arg().
- Use string_is_key_value() in parse_bridge_line().
- Parenthesize a forgotten #define
- Add some more comments.
- Add some more unit test cases.
Also, deprecate the torrc options for the scaling values. It's unlikely anyone
but developers will ever tweak them, even if we provided a single ratio value.
This is meant to avoid conflict with the built-in log() function in
math.h. It resolves ticket 7599. First reported by dhill.
This was generated with the following perl script:
#!/usr/bin/perl -w -i -p
s/\blog\(LOG_(ERR|WARN|NOTICE|INFO|DEBUG)\s*,\s*/log_\L$1\(/g;
s/\blog\(/tor_log\(/g;
Instead of hardcoding the minimum fraction of possible paths to 0.6, we
take it from the user, and failing that from the consensus, and
failing that we fall back to 0.6.
Path use bias measures how often we can actually succeed using the circuits we
actually try to use. It is a subset of path bias accounting, but it is
computed as a separate statistic because the rate of client circuit use may
vary depending on use case.
This is ticket 7706, reported by "bugcatcher." The rationale here
is that if somebody says 'ExcludeNodes {tv}', then they probably
don't just want to block definitely Tuvaluan nodes: they also want
to block nodes that have unknown country, since for all they know
such nodes are also in Tuvalu.
This behavior is controlled by a new GeoIPExcludeUnknown autobool
option. With the default (auto) setting, we exclude ?? and A1 if
any country is excluded. If the option is 1, we add ?? and A1
unconditionally; if the option is 0, we never add them.
(Right now our geoip file doesn't actually seem to include A1: I'm
including it here in case it comes back.)
This feature only takes effect if you have a GeoIP file. Otherwise
you'd be excluding every node.
The right way to set "MaxOnionsPending" was to adjust it until the
processing delay was appropriate. So instead, let's measure how long
it takes to process onionskins (sampling them once we have a big
number), and then limit the queue based on its expected time to
finish.
This change is extra-necessary for ntor, since there is no longer a
reasonable way to set MaxOnionsPending without knowing what mix of
onionskins you'll get.
This patch also reserves 1/3 of the onionskin spots for ntor
handshakes, on the theory that TAP handshakes shouldn't be allowed to
starve their speedier cousins. We can change this later if need be.
Resolves 7291.
Our old warn_nonlocal_client_ports() would give a bogus warning for
every nonlocal port every time it parsed any ports at all. So if it
parsed a nonlocal socksport, it would complain that it had a nonlocal
socksport...and then turn around and complain about the nonlocal
socksport again, calling it a nonlocal transport or nonlocal dnsport,
if it had any of those.
Fixes bug 7836; bugfix on 0.2.3.3-alpha.
With an IPv6 virtual address map, we can basically hand out a new
IPv6 address for _every_ address we connect to. That'll be cool, and
will let us maybe get around prop205 issues.
This uses some fancy logic to try to make the code paths in the ipv4
and the ipv6 case as close as possible, and moves to randomly
generated addresses so we don't need to maintain those stupid counters
that will collide if Tor restarts but apps don't.
Also has some XXXX items to fix to make this useful. More design
needed.
This function gives us a single place to set reasonable default flags
for port_cfg_t entries, to avoid bugs like the one where we weren't
setting ipv4_traffic_ok to 1 on SocksPorts initialized in an older
way.
(This is part 1 of making DNS cache use enabled/disabled on a
per-client port basis. These options are shuffled around correctly,
but don't do anything yet.)
Turns out there's more than one way to block a tagged circuit.
This seems to successfully handle all of the normal exit circuits. Hidden
services need additional tweaks, still.
This replaces the old FallbackConsensus notion, and should provide a
way -- assuming we pick reasonable nodes! -- to give clients
suggestions of placs to go to get their first consensus.
Now creating a dir_server_t and adding it are separate functions, and
there are frontend functions for adding a trusted dirserver and a
fallback dirserver.
We use trusted_dir_server_t for two pieces of functionality: a list of
all directory authorities, and a list of initial places to look for
a directory. With this patch we start to separate those two roles.
There is as of now no actual way to be a fallback directory without being
an authority.
Looks like when i was writing the code to set the ipv4_traffic flag on
port_cfg_t, I missed some cases, such as the one where the port was
set from its default value.
Fix for 7493. Bug not in any released Tor.
These options are for telling the SOCKSPort that it should allow or
not allow connections to IPv4/IPv6 addresses.
These aren't implemented yet; this is just the code to read the
options and get them into the entrey_connection_t.
By default, "*" means "All IPv4 addresses" with
tor_addr_parse_mask_ports, so I won't break anything. But if the new
EXTENDED_STAR flag is provided, then * means "any address", *4 means
"any IPv4 address" (that is, 0.0.0.0/0), and "*6" means "any IPv6
address" (that is, [::]/0).
This is going to let us have a syntax for specifying exit policies in
torrc that won't drive people mad.
Also, add a bunch of unit tests for tor_addr_parse_mask_ports to test
these new features, and to increase coverage.
Instead of warning about low ports that are advertised, we should have
been warning about low ports that we're listening on. Bug 7285, fix
on 0.2.3.9-alpha.
Conflicts:
src/or/circuitbuild.c
The conflict was trivial, since no line of code actually changed in
both branches: There was a fmt_addr() that turned into fmt_addrport()
in bug7011, and a "if (!n_conn)" that turned into "if (!n_chan)" in
master.
This is mostly a conversion from this pattern:
log("... %s:%d ...", fmt_and_decorate_addr(&addr), port);
to this:
log("... %s ...", fmt_addrport(&addr, port));
The output is the same in all cases.
we can turn it into an autobool later if we have some way for it
to make a decision.
(patch possibly got lost when nickm merged #6770; or maybe nickm meant
for it to be this way. i'm not sure.)
See #4771 for rationale.
Note that this patch does not take suggested changes in #4470 into
account and keeps treating AuthDirHasIPv6Connectivity as an
AUTOBOOL. Thus, bug fixes for that are included here as well.
This is a fix on master, unreleased as of now.
Add ClientUseIPv6 and ClientPreferIPv6ORPort configuration options.
Use "preferred OR port" for all entry nodes, not only for bridges.
Mark bridges with "prefer IPv6 OR port" if an IPv6 address is
configured in Bridge line and ClientPreferIPv6ORPort is set.
Mark relays with "prefer IPv6 OR port" if an IPv6 address is found in
descriptor and ClientPreferIPv6ORPort is set.
Filter "preferred OR port" through the ClientUseIPv6 config option. We
might want to move this test to where actual connection is being set
up once we have a fall back mechanism in place.
Have only non-servers pick an IPv6 address for the first hop: We
don't want relays to connect over IPv6 yet. (IPv6 has never been used
for second or third hops.)
Implements ticket 5535.
This is important, since otherwise an attacker can use timing info
to probe the internal network.
Also, add an option (ExtendAllowPrivateAddresses) so that
TestingTorNetwork won't break.
Fix for bug 6710; bugfix on all released versions of Tor.
This patch extracts the inner part of config_register_addressmaps --
the part that knows about detecting wildcard addresses addresses --
and makes it into a new function. The new function is deliberately
not moved or reindented, so that the diff is smaller.
I need this to fix bug 6244.
Thanks to the changes we started making with SocksPort and friends
in 0.2.3.3-alpha, any of our code that did "if (options->Sockport)"
became wrong, since "SocksPort 0" would make that test true whereas
using the default SocksPort value would make it false. (We didn't
actually do "if (options->SockPort)" but we did have tests for
TransPort. When we moved DirPort, ORPort, and ControlPort over to
the same system in 0.2.3.9-alpha, the problem got worse, since our
code is littered with checks for DirPort and ORPort as booleans.
This code renames the current linelist-based FooPort options to
FooPort_lines, and adds new FooPort_set options which get set at
parse-and-validate time on the or_options_t. FooPort_set is true
iff we will actually try to open a listener of the given type. (I
renamed the FooPort options rather than leave them alone so that
every previous user of a FooPort would need to get inspected, and so
that any new code that forgetfully uses FooPort will need fail to
compile.)
Fix for bug 6507.
Test for config option AuthDirPublishIPv6 == 1 rather than for running
as a bridge authority when deciding whether to care or not about IPv6
OR ports in descriptors.
Implements enhancement #6406.
The SMARTLIST_FOREACH macro is more convenient than BEGIN/END when
you have a nice short loop body, but using it for long bodies makes
your preprocessor tell the compiler that all the code is on the same
line. That causes grief, since compiler warnings and debugger lines
will all refer to that one line.
So, here's a new style rule: SMARTLIST_FOREACH blocks need to be
short.
The defense counts the circuit failure rate for each guard for the past N
circuits. Failure is defined as the ability to complete a first hop, but not
finish completing the circuit all the way to the exit.
If the failure rate exceeds a certain amount, a notice is emitted.
If it exceeds a greater amount, a warn is emitted and the guard is disabled.
These values are governed by consensus parameters which we intend to tune as
we perform experiments and statistical simulations.
From what I can tell, this configuration is usually a mistake, and
leads people to think that all their traffic is getting proxied when
in fact practically none of it is. Resolves the issue behind "bug"
4663.
