Inform the control port with an HS_DESC failed event when the client is unable
to pick an HSDir. It's followed by an empty HS_DESC_CONTENT event. In order to
achieve that, some control port code had to be modified to accept a NULL HSDir
identity digest.
This commit also adds a trigger of a failed event when we are unable to
base64-decode the descriptor cookie.
Fixes#22042
Signed-off-by: David Goulet <dgoulet@torproject.org>
Introduce a way to optionally enable Rust integration for our builds. No
actual Rust code is added yet and specifying the flag has no effect
other than failing the build if rustc and cargo are unavailable.
This commit adds the src/trace directory containing the basics for our tracing
subsystem. It is not used in the code base. The "src/trace/debug.h" file
contains an example on how we can map our tor trace events to log_debug().
The tracing subsystem can only be enabled by tracing framework at compile
time. This commit introduces the "--enable-tracing-debug" option that will
make all "tor_trace()" function be maped to "log_debug()".
Closes#13802
Signed-off-by: David Goulet <dgoulet@torproject.org>
That log statement can be triggered if somebody on the Internet behaves badly
which is possible with buggy implementation for instance.
Fixes#21293
Signed-off-by: David Goulet <dgoulet@torproject.org>
This patch ensures that Tor checks if a given compression method is
supported before printing the version string when calling `tor
--library-versions`.
Additionally, we use the `tor_compress_supports_method()` to check if a
given version is supported for Tor's start-up version string, but here
we print "N/A" if a given compression method is unavailable.
See: https://bugs.torproject.org/21662
This patch adds the `tor_compress_get_total_allocation()` which returns
an approximate number of bytes currently in use by all the different
compression backends.
See: https://bugs.torproject.org/21662
This patch adds support for enabling support for Zstandard to our configure
script. By default, the --enable-zstd option is set to "auto" which means if
libzstd is available we'll build Tor with Zstandard support.
See: https://bugs.torproject.org/21662
This patch adds support for enabling support for LZMA to our configure
script. By default, the --enable-lzma option is set to "auto" which
means if liblzma is available we'll build Tor with LZMA support.
See: https://bugs.torproject.org/21662
This patch refactors the `torgzip` module to allow us to extend a common
compression API to support multiple compression backends.
Additionally we move the gzip/zlib code into its own module under the
name `compress_zlib`.
See https://bugs.torproject.org/21664
Remove duplicate code that validates a service object which is now in
rend_validate_service().
Add some comments on why we nullify a service in the code path of
rend_config_services().
Signed-off-by: David Goulet <dgoulet@torproject.org>
This new function validates a service object and is used everytime a service
is successfully loaded from the configuration file.
It is currently copying the validation that rend_add_service() also does which
means both functions validate. It will be decoupled in the next commit.
Signed-off-by: David Goulet <dgoulet@torproject.org>
In several places in the old code, we had problems that only an
in-memory index of diff status could solve, including:
* Remembering which diffs were in-progress, so that we didn't
re-launch them.
* Remembering which diffs had failed, so that we didn't try to
recompute them over and over.
* Having a fast way to look up the diff from a given consensus to
the latest consensus of a given flavor.
This patch adds a hashtable mapping from (flavor, source diff), to
solve the problem. It maps to a cache entry handle, rather than to
a cache entry directly, so that it doesn't affect the reference
counts of the cache entries, and so that we don't otherwise need to
worry about lifetime management.
This conscache flag tells conscache that it should munmap the
document as soon as reasonably possible, since its usage pattern is
expected to not have a lot of time-locality.
Initial tests. These just try adding a few consensuses, looking
them up, and making sure that consensus diffs are generated in a
more or less reasonable-looking way. It's enough for 87% coverage,
but it leaves out a lot of functionality.
This module's job is to remember old consensus documents, to
calculate their diffs on demand, and to .
There are some incomplete points in this code; I've marked them with
"XXXX". I intend to fix them in separate commits, since I believe
doing it in separate commits will make the branch easier to review.
The GETINFO extra-info/digest/<digest> broke in commit 568dc27a19 that
refactored the base16_decode() API to return the decoded length.
Unfortunately, that if() condition should have checked for the correct length
instead of an error which broke the command in tor-0.2.9.1-alpha.
Fixes#22034
Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit mainly moves the responsibility for directory request
construction one level higher. It also allows a directory request
to contain a pointer to a routerstatus, which will get turned into
the correct contact information at the last minute.
We do dump HS stats now at log info everytime the intro circuit creation retry
period limit has been reached. However, the log was upgraded to warning if we
actually were over the elapsed time (plus an extra slop).
It is actually something that will happen in tor in normal case. For instance,
if the network goes down for 10 minutes then back up again making
have_completed_a_circuit() return false which results in never updating that
retry period marker for a service.
Fixes#22032
Signed-off-by: David Goulet <dgoulet@torproject.org>
This patch refactors our streaming compression code to allow us to
extend it with non-zlib/non-gzip based compression schemas.
See https://bugs.torproject.org/21663
To allow us to use the API name `tor_compress` and `tor_uncompress` as
the main entry-point for all compression/uncompression and not just gzip
and zlib.
See https://bugs.torproject.org/21663
The consdiff generation logic would skip over lines added at the start of the
second file, and generate a diff that it would the immediately refuse because
it couldn't be used to reproduce the second file from the first. Fixes#21996.
The reason for making the temporary list public is to keep it encapsulated in
the rendservice subsystem so the prop224 code does not have direct access to
it and can only affect it through the rendservice pruning function.
It also has been modified to not take list as arguments but rather use the
global lists (main and temporary ones) because prop224 code will call it to
actually prune the rendservice's lists. The function does the needed rotation
of pointers between those lists and then prune if needed.
In order to make the unit test work and not completely horrible, there is a
"impl_" version of the function that doesn't free memory, it simply moves
pointers around. It is directly used in the unit test and two setter functions
for those lists' pointer have been added only for unit test.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Now we have separate getters and setters for service-side and relay-side. I
took this approach over adding arguments to the already existing methods to
have more explicit type-checking, and also because some functions would grow
too large and dirty.
This commit also fixes every callsite to use the new function names which
modifies the legacy HS (v2) and the prop224 (v3) code.
Signed-off-by: David Goulet <dgoulet@torproject.org>
One of the goals of this change is to have trunnel API/ABI being more explicit
so we namespace them with "trn_*". Furthermore, we can now create
hs_cells.[ch] without having to confuse it with trunnel which used to be
"hs_cell_*" before that change.
Here are the perl line that were used for this rename:
perl -i -pe 's/cell_extension/trn_cell_extension/g;' src/*/*.[ch]
perl -i -pe 's/cell_extension/trn_cell_extension/g;' src/trunnel/hs/*.trunnel
perl -i -pe 's/hs_cell_/trn_cell_/g;' src/*/*.[ch]
perl -i -pe 's/hs_cell_/trn_cell_/g;' src/trunnel/hs/*.trunnel
And then "./scripts/codegen/run_trunnel.sh" with trunnel commit id
613fb1b98e58504e2b84ef56b1602b6380629043.
Fixes#21919
Signed-off-by: David Goulet <dgoulet@torproject.org>
Pinning EntryNodes along with hidden services can be possibly harmful (for
instance #14917 and #21155) so at the very least warn the operator if this is
the case.
Fixes#21155
Signed-off-by: David Goulet <dgoulet@torproject.org>
Now that base64_decode() checks the destination buffer length against
the actual number of bytes as they're produced, shared_random.c no
longer needs the "SR_COMMIT_LEN+2" workaround.
Note down in the routerstatus_t of a node if the router supports the HSIntro=4
version for the ed25519 authentication key and HSDir=2 version for the v3
descriptor supports.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Some of those defines will be used by the v3 HS protocol so move them to a
common header out of rendservice.c. This is also ground work for prop224
service implementation.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Another building blocks for prop224 service work. This also makes the function
takes specific argument instead of the or_option_t object.
Signed-off-by: David Goulet <dgoulet@torproject.org>
When a client tried to connect to an invalid port of an hidden service, a
warning was printed:
[warn] connection_edge_process_relay_cell (at origin) failed.
This is because the connection subsystem wants to close the circuit because
the port can't be found and then returns a negative reason to achieve that.
However, that specific situation triggered a warning. This commit prevents it
for the specific case of an invalid hidden service port.
Fixes#16706
Signed-off-by: David Goulet <dgoulet@torproject.org>
In order to avoid src/or/hs_service.o to contain no symbols and thus making
clang throw a warning, the functions are now exposed not just to unit tests.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Add a new helper function route_len_for_purpose(), which explicitly
lists all of the known circuit purposes for a circuit with a chosen
exit node (unlike previously, where the default route length for a
chosen exit was DEFAULT_ROUTE_LEN + 1 except for two purposes). Add a
non-fatal assertion for unhandled purposes that conservatively returns
DEFAULT_ROUTE_LEN + 1.
Add copious comments documenting which circuits need an extra hop and
why.
Thanks to nickm and dgoulet for providing background information.
The old implementation had duplicated code in a bunch of places, and
it interspersed spool-management with resource management. The new
implementation should make it easier to add new resource types and
maintain the spooling code.
Closing ticket 21651.
When calculating max sampled size, Tor would only count the number of
bridges in torrc, without considering that our state file might already
have sampled bridges in it. This caused problems when people swap
bridges, since the following error would trigger:
[warn] Not expanding the guard sample any further; just hit the
maximum sample threshold of 1
This patch changes the way we decide when to check for whether it's time
to rotate and/or expiry our onion keys. Due to proposal #274 we can now
have the keys rotate at different frequencies than before and we thus
do the check once an hour when our Tor daemon is running in server mode.
This should allow us to quickly notice if the network consensus
parameter have changed while we are running instead of having to wait
until the current parameters timeout value have passed.
See: See: https://bugs.torproject.org/21641
This patch adds a new timer that is executed when it is time to expire
our current set of old onion keys. Because of proposal #274 this can no
longer be assumed to be at the same time we rotate our onion keys since
they will be updated less frequently.
See: https://bugs.torproject.org/21641
This patch adds an API to get the current grace period, in days, defined
as the consensus parameter "onion-key-grace-period-days".
As per proposal #274 the values for "onion-key-grace-period-days" is a
default value of 7 days, a minimum value of 1 day, and a maximum value
defined by other consensus parameter "onion-key-rotation-days" also
defined in days.
See: https://bugs.torproject.org/21641
This patch turns `MIN_ONION_KEY_LIFETIME` into a new function
`get_onion_key_lifetime()` which gets its value from a network consensus
parameter named "onion-key-rotation-days". This allows us to tune the
value at a later point in time with no code modifications.
We also bump the default onion key lifetime from 7 to 28 days as per
proposal #274.
See: https://bugs.torproject.org/21641
There was a frequent block of code that did "find the next router
line, see if we've hit the end of the list, get the ID hash from the
line, and enforce well-ordering." Per Ahf's review, I'm extracting
it to its own function.
Previously, we operated on smartlists of NUL-terminated strings,
which required us to copy both inputs to produce the NUL-terminated
strings. Then we copied parts of _those_ inputs to produce an
output smartlist of NUL-terminated strings. And finally, we
concatenated everything into a final resulting string.
This implementation, instead, uses a pointer-and-extent pattern to
represent each line as a pointer into the original inputs and a
length. These line objects are then added by reference into the
output. No actual bytes are copied from the original strings until
we finally concatenate the final result together.
Bookkeeping structures and newly allocated strings (like ed
commands) are allocated inside a memarea, to avoid needless mallocs
or complicated should-I-free-this-or-not bookkeeping.
In my measurements, this improves CPU performance by something like
18%. The memory savings should be much, much higher.
Also, add very strict split/join functions, and totally forbid
nonempty files that end with somethig besides a newline. This
change is necessary to ensure that diff/apply are actually reliable
inverse operations.
The 2-line diff changs is needed to make the unit tests actually
test the cases that they thought they were testing.
The bogus free was found while testing those cases
(This commit was extracted by nickm based on the final outcome of
the project, taking only the changes in the files touched by this
commit from the consdiff_rebased branch. The directory-system
changes are going to get worked on separately.)
Also, relaxed the checks of encrypted_data_length_is_valid() since now
only one encrypted section has padding requirements and we don't
actually care to check that all the padding is there.
Consider starting code review from function encode_superencrypted_data().
- Refactor our HS desc crypto funcs to be able to differentiate between
the superencrypted layer and the encrypted layer so that different
crypto constants and padding is used in each layer.
- Introduce some string constants.
- Add some comments.
As part of the work for proposal #274 we are going to remove the need
for MIN_ONION_KEY_LIFETIME and turn it into a dynamic value defined by a
consensus parameter.
See: https://bugs.torproject.org/21641
The bridges+ipv6-min integration test has a client with bridges:
Bridge 127.0.0.1:5003
Bridge [::1]:5003
which got stuck in guard_selection_have_enough_dir_info_to_build_circuits()
because it couldn't find the descriptor of both bridges.
Specifically, the guard_has_descriptor() function could not find the
node_t of the [::1] bridge, because the [::1] bridge had no identity
digest assigned to it.
After further examination, it seems that during fetching the descriptor
for our bridges, we used the CERTS cell to fill the identity digest of
127.0.0.1:5003 properly. However, when we received a CERTS cell from
[::1]:5003 we actually ignored its identity digest because the
learned_router_identity() function was using
get_configured_bridge_by_addr_port_digest() which was returning the
127.0.0.1 bridge instead of the [::1] bridge (because it prioritizes
digest matching over addrport matching).
The fix replaces get_configured_bridge_by_addr_port_digest() with the
recent get_configured_bridge_by_exact_addr_port_digest() function. It
also relaxes the constraints of the
get_configured_bridge_by_exact_addr_port_digest() function by making it
return bridges whose identity digest is not yet known.
By using the _exact_() function, learned_router_identity() actually
fills in the identity digest of the [::1] bridge, which then allows
guard_has_descriptor() to find the right node_t and verify that the
descriptor is there.
FWIW, in the bridges+ipv6-min test both 127.0.0.1 and [::1] bridges
correspond to the same node_t, which I guess makes sense given that it's
actually the same underlying bridge.
This patch removes the `tor_fgets()` wrapper around `fgets(3)` since it
is no longer needed. The function was created due to inconsistency
between the returned values of `fgets(3)` on different versions of Unix
when using `fgets(3)` on non-blocking file descriptors, but with the
recent changes in bug #21654 we switch from unbuffered to direct I/O on
non-blocking file descriptors in our utility module.
We continue to use `fgets(3)` directly in the geoip and dirserv module
since this usage is considered safe.
This patch also removes the test-case that was created to detect
differences in the implementation of `fgets(3)` as well as the changes
file since these changes was not included in any releases yet.
See: https://bugs.torproject.org/21654
Make hidden services with 8 to 10 introduction points check for failed
circuits immediately after startup. Previously, they would wait for 5
minutes before performing their first checks.
Fixes bug 21594; bugfix on commit 190aac0eab in Tor 0.2.3.9-alpha.
Reported by alecmuffett.
This change is the only one necessary to allow future versions of
the microdescriptor consensus to replace every 'published' date with
e.g. 2038-01-01 00:00:00; this will save 50-75% in compressed
microdescriptor diff size, which is quite significant.
This commit is a minimal change for 0.2.9; future series will
reduce the use of the 'published' date even more.
Implements part of ticket 21642; implements part of proposal 275.
Previously, they would stop checking when they exceeded their intro point
creation limit.
Fixes bug 21596; bugfix on commit d67bf8b2f2 in Tor 0.2.7.2-alpha.
Reported by alecmuffett.
Previously, they would stop checking when they exceeded their intro point
creation limit.
Fixes bug 21596; bugfix on commit d67bf8b2f2 in Tor 0.2.7.2-alpha.
Reported by alecmuffett.
In that chutney test, the bridge client is configured to connect to
the same bridge at 127.0.0.1:5003 _and_ at [::1]:5003, with no
change in transports.
That meant, I think, that the descriptor is only assigned to the
first bridge when it arrives, and never the second.
- Make sure we check at least two guards for descriptor before making
circuits. We typically use the first primary guard for circuits, but
it can also happen that we use the second primary guard (e.g. if we
pick our first primary guard as an exit), so we should make sure we
have descriptors for both of them.
- Remove BUG() from the guard_has_descriptor() check since we now know
that this can happen in rare but legitimate situations as well, and we
should just move to the next guard in that case.
Previously I'd made a bad assumption in the implementation of
prop271 in 0.3.0.1-alpha: I'd assumed that there couldn't be two
guards with the same identity. That's true for non-bridges, but in
the bridge case, we allow two bridges to have the same ID if they
have different addr:port combinations -- in order to have the same
bridge ID running multiple PTs.
Fortunately, this assumption wasn't deeply ingrained: we stop
enforcing the "one guard per ID" rule in the bridge case, and
instead enforce "one guard per <id,addr,port>".
We also needed to tweak our implementation of
get_bridge_info_for_guard, since it made the same incorrect
assumption.
Fixes bug 21027; bugfix on 0.3.0.1-alpha.
This feature makes it possible to turn off memory sentinels (like
those used for safety in buffers.c and memarea.c) when fuzzing, so
that we can catch bugs that they would otherwise prevent.
Teor thinks that this connection_dirserv_add_dir_bytes_to_outbuf()
might be the problem, if the "remaining" calculation underflows. So
I'm adding a couple of checks there, and improving the casts.
When encoding a legacy ESTABLISH_INTRO cell, we were using the sizeof() on a
pointer instead of using the real size of the destination buffer leading to an
overflow passing an enormous value to the signing digest function.
Fortunately, that value was only used to make sure the destination buffer
length was big enough for the key size and in this case it always was because
of the overflow.
Fixes#21553
Signed-off-by: David Goulet <dgoulet@torproject.org>
strto* and _atoi64 accept +, -, and various whitespace before numeric
characters. And permitted whitespace is different between POSIX and Windows.
Fixes bug 21507 and part of 21508; bugfix on 0.0.8pre1.
This patch makes us store the number of sent and received RELAY_DATA
cells used for directory connections. We log the numbers after we have
received an EOF in connection_dir_client_reached_eof() from the
directory server.
Instead of returning 404 error code, this led to a NULL pointer being used and
thus a crash of tor.
Fixes#21471
Signed-off-by: David Goulet <dgoulet@torproject.org>
Fixes bug 20894; bugfix on 0.2.0.16-alpha.
We already applied a workaround for this as 20834, so no need to
freak out (unless you didn't apply 20384 yet).
This should be "impossible" without making a SHA1 collision, but
let's not keep the assumption that SHA1 collisions are super-hard.
This prevents another case related to 21278. There should be no
behavioral change unless -ftrapv is on.
I think this one probably can't underflow, since the input ranges
are small. But let's not tempt fate.
This patch also replaces the "cmp" functions here with just "eq"
functions, since nothing actually checked for anything besides 0 and
nonzero.
Related to 21278.
Fix for TROVE-2017-001 and bug 21278.
(Note: Instead of handling signed ints "correctly", we keep the old
behavior, except for the part where we would crash with -ftrapv.)
This is a purely cosmetic patch that changes RELAY_BEGINDIR in various
comments to RELAY_BEGIN_DIR, which should make it easier to grep for the
symbols.
This patch ensures that we log the size of the inbuf when a directory
client have reached EOF on the connection.
See: https://bugs.torproject.org/21206
This patch makes the log-statements in `connection_dir_client_reached_eof`
more explicit by writing "body size" instead of just "size" which could
be confused as being the size of the entire response, which would
include HTTP status-line and headers.
See: https://bugs.torproject.org/21206
This reverts commit 5446cb8d3d.
The underlying revert was done in 0.2.6, since we aren't backporting
seccomp2 loosening fixes to 0.2.6. But the fix (for 17354) already
went out in 0.2.7.4-rc, so we shouldn't revert it in 0.2.7.
This patch adds a debug log statement when sending a request to a
directory server. The information logged includes: the payload size (if
available), the total size of the request, the address and port of the
directory server, and the purpose of the directory connection.
See: https://bugs.torproject.org/21206
maint-0.2.7-redux is an attempt to try to re-create a plausible
maint-0.2.7 branch. I've started from the tor-0.2.7.6, and then I
merged maint-0.2.6 into the branch.
This has produced 2 conflicts: one related to the
rendcommon->rendcache move, and one to the authority refactoring.
The length of auth_data from an INTRODUCE2 cell is checked when the
auth_type is recognized (1 or 2), but not for any other non-zero
auth_type. Later, auth_data is assumed to have at least
REND_DESC_COOKIE_LEN bytes, leading to a client-triggered out of bounds
read.
Fixed by checking auth_len before comparing the descriptor cookie
against known clients.
Fixes#15823; bugfix on 0.2.1.6-alpha.
Bug 21242 occurred because we asserted that extend_info_from_node()
had succeeded...even though we already had the code to handle such a
failure. We fixed that in 93b39c5162.
But there were four other cases in our code where we called
extend_info_from_node() and either tor_assert()ed that it returned
non-NULL, or [in one case] silently assumed that it returned
non-NULL. That's not such a great idea. This patch makes those
cases check for a bug of this kind instead.
Fixes bug 21372; bugfix on 0.2.3.1-alpha when
extend_info_from_node() was introduced.
Once a second, we go over all services and consider the validity of the intro
points. Now, also try to remove expiring nodes that have no more circuit
associated to them. This is possible if we moved an intro point object
previously to that list and the circuit actually timed out or was closed by
the introduction point itself.
Signed-off-by: David Goulet <dgoulet@torproject.org>
In rend_service_intro_has_opened(), this is subject to a possible underflow
because of how the if() casts the results. In the case where the expiring
nodes list length is bigger than the number of IP circuits, we end up in the
following situation where the result will be cast to an unsigned int. For
instance, "5 - 6" is actually a BIG number.
Ultimately leading to closing IP circuits in a non stop loop.
Partially fixes#21302.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Previously the dirserv_orconn_tls_done() function would skip routers
when they advertised an ed25519 key but didn't present it during the
link handshake. But that covers all versions between 0.2.7.2-alpha
and 0.2.9.x inclusive!
Fixes bug 21107; bugfix on 0.3.0.1-alpha.
Because we don't allow client functionalities in non anonymous mode,
recommending Tor2web is a bad idea.
If a user wants to use Tor2web as a client (losing all anonymity), it should
run a second tor, not use it with a single onion service tor.
Fixes#21294.
Signed-off-by: David Goulet <dgoulet@torproject.org>
In rend_consider_services_intro_points(), we had a possible interger underflow
which could lead to creating a very large number of intro points. We had a
safe guard against that *except* if the expiring_nodes list was not empty
which is realistic thing.
This commit removes the check on the expiring nodes length being zero. It's
not because we have an empty list of expiring nodes that we don't want to open
new IPs. Prior to this check, we remove invalid IP nodes from the main list of
a service so it should be the only thing to look at when deciding if we need
to create new IP(s) or not.
Partially fixes#21302.
Signed-off-by: David Goulet <dgoulet@torproject.org>
This disregards anything smaller than an IPv6 /64, and rejects ports that
are rejected on an IPv6 /16 or larger.
Adjust existing unit tests, and add more to cover exceptional cases.
No IPv4 behaviour changes.
Fixes bug 21357
This interim fix results in too many IPv6 rejections.
No behaviour change for IPv4 counts, except for overflow fixes that
would require 4 billion redundant 0.0.0.0/0 policy entries to trigger.
Part of 21357
Stop modifying the value of our torrc option HiddenServiceStatistics just
because we're not a bridge or relay. This bug was causing Tor Browser users to
write "HiddenServiceStatistics 0" in their torrc files as if they had chosen
to change the config.
Fixes#21150
Signed-off-by: David Goulet <dgoulet@torproject.org>
Since we can call this function more than once before we update all
the confirmed_idx fields, we can't rely on all the relays having an
accurate confirmed_idx.
Fixes bug 21129; bugfix on 0.3.0.1-alpha
We need to call it before nt_service_parse_options(), since
nt_service_parse_options() can call back into nt_service_main(),
which calls do_main_loop().
Fixes bug 21356; bugfix on 0.2.9.1-alpha.
In addition to not wanting to build circuits until we can see most
of the paths in the network, and in addition to not wanting to build
circuits until we have a consensus ... we shouldn't build circuits
till all of our (in-use) primary guards have descriptors that we can
use for them.
This is another bug 21242 fix.
Actually, it's _fine_ to use a descriptorless guard for fetching
directory info -- we just shouldn't use it when building circuits.
Fortunately, we already have a "usage" flag that we can use here.
Partial fix for bug 21242.
This relates to the 21242 fix -- entry_guard_pick_for_circuit()
should never yield nodes without descriptors when the node is going
to be used for traffic, since we won't be able to extend through
them.
This assertion triggered in the (error) case where we got a result
from guards_choose_guard() without a descriptor. That's not
supposed to be possible, but it's not worth crashing over.
I broke "GETCONF *Port" in 20956, when I made SocksPort a
subordinate option of the virtual option SocksPortLines, so that I
could make SocksPort and __SocksPort provide qthe same
functionality. The problem was that you can't pass a subordinate
option to GETCONF.
So, this patch fixes that by letting you fetch subordinate options.
It won't always be meaningful to consider these options
out-of-context, but that can be the controller-user's
responsibility to check.
Closes ticket 21300.
