Because of #23387, we've realized that there is one scenario that makes
the client unable to reach the service because of a desynch in the time
period used. The scenario is as follows:
+------------------------------------------------------------------+
| |
| 00:00 12:00 00:00 12:00 00:00 12:00 |
| SRV#1 TP#1 SRV#2 TP#2 SRV#3 TP#3 |
| |
| $==========|-----------$===========|-----------$===========| |
| ^ ^ |
| C S |
+------------------------------------------------------------------+
In this scenario the HS has a newer consensus than the client, and the
HS just moved to the next TP but the client is still stuck on the old
one. However, the service is not in any sort of overlap mode so it
doesn't cover the old TP anymore, so the client is unable to fetch a
descriptor.
We've decided to solve this by extending the concept of overlap period
to be permanent so that the service always publishes two descriptors and
aims to cover clients with both older and newer consensuses. See the
spec patch in #23387 for more details.
Based on our #23387 findings, it seems like to maintain 24/7
reachability we need to employ different logic when computing hsdir
indices for fetching vs storing. That's to guarantee that the client
will always fetch the current descriptor, while the service will always
publish two descriptors aiming to cover all possible edge cases.
For more details see the next commit and the spec branch.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Use the valid_after time from the consensus to get the time period number else
we might get out of sync with the overlap period that uses valid_after.
Make it an optional feature since some functions require passing a
specific time (like hs_get_start_time_of_next_time_period()).
Signed-off-by: David Goulet <dgoulet@torproject.org>
That check was wrong:
a) We should be making sure that the size of `key` is big enough before
proceeding, since that's the buffer that we would overread with the
tor_memeq() below.
The old check used to check that `req_key_str` is big enough which is
not right, since we won't read deep into that buffer.
The new check makes sure that `key` has enough size to survive the
tor_memeq(), and if not it moves to the next element of the strmap.
b) That check shouldn't be a BUG since that strmap contains
variable-sized elements and we should not be bugging out if we happen
to compare a small sized element (v2) to a bigger one (v3).
The hs circuit file had this function that takes a list of link specifiers and
return a newly allocated extend info object. Make it public so the client side
can also use it to be able to extend to introduction point.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Put all the possible assert() we can do on a client introduction circuit in
one helper function to make sure it is valid and usable.
It is disabled for now so gcc doesn't complain that we have a unused function.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Specifically move the pick_hsdir() function and all the HSDir request tracking
code. We plan to use all that code both for v2 and v3.
This commit only moves code.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Add a common function for both legacy and prop224 hidden service to increment
and decrement the rendezvous stream counter on an origin circuit.
Signed-off-by: David Goulet <dgoulet@torproject.org>
We used to do:
h = H(BLIND_STRING | H(A | s | B | N )
when we should be doing:
h = H(BLIND_STRING | A | s | B | N)
Change the logic so that hs_common.c does the hashing, and our ed25519
libraries just receive the hashed parameter ready-made. That's easier
than doing the hashing on the ed25519 libraries, since that means we
would have to pass them a variable-length param (depending on whether
's' is set or not).
Also fix the ed25519 test vectors since they were also double hashing.
We also had to alter the SRV functions to take a consensus as optional
input, since we might be setting our HSDir index using a consensus that
is currently being processed and won't be returned by the
networkstatus_get_live_consensus() function.
This change has two results:
a) It makes sure we are using a fresh consensus with the right SRV value
when we are calculating the HSDir hash ring.
b) It ensures that we will not use the sr_get_current/previous()
functions when we don't have a consensus which would have falsely
triggered the disaster SRV logic.
We consider to be in overlap mode when we are in the period of time between a
fresh SRV and the beginning of the new time period (in the normal network this
is between 00:00 and 12:00 UTC). This commit edits that function to use the
above semantic logic instead of absolute times.
Signed-off-by: David Goulet <dgoulet@torproject.org>
It used to be that time periods were 24 hours long even on chutney,
which made testing harder. With this commit, time periods have the same
length as a full SRV protocol run, which means that they will change
every 4 minutes in a 10-second voting interval chutney network!
This commit refactors the handle_hs_exit_conn() function introduced at a prior
commit that connects the rendezvous circuit to the edge connection used to
connect to the service virtual port requested in a BEGIN cell.
The refactor adds the support for prop224 adding the
hs_service_set_conn_addr_port() function that has the same purpose has
rend_service_set_connection_addr_port() from the legacy code.
The rend_service_set_connection_addr_port() has also been a bit refactored so
the common code can be shared between the two HS subsystems (legacy and
prop224).
In terms of functionallity, nothing has changed, we still close the circuits
in case of failure for the same reasons as the legacy system currently does.
Signed-off-by: David Goulet <dgoulet@torproject.org>
This hsdir index value is used to give an index value to all node_t (relays)
that supports HSDir v3. An index value is then computed using the blinded key
to know where to fetch/upload the service descriptor from/to.
To avoid computing that index value everytime the client/service needs it, we
do that everytime we get a new consensus which then doesn't change until the
next one. The downside is that we need to sort them once we need to compute
the set of responsible HSDir.
Finally, the "hs_index" function is also added but not used. It will be used
in later commits to compute which node_t is a responsible HSDir for the
service we want to fetch/upload the descriptor.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Add a function for both the client and service side that is building a blinded
key from a keypair (service) and from a public key (client). Those two
functions uses the current time period information to build the key.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Try to load or/and generate service keys for v3. This write both the public
and private key file to disk along with the hostname file containing the onion
address.
Signed-off-by: David Goulet <dgoulet@torproject.org>
This also adds unit test and a small python script generating a deterministic
test vector that a unit test tries to match.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Introduces hs_init() located in hs_common.c which initialize the entire HS v3
subsystem. This is done _prior_ to the options being loaded because we need to
allocate global data structure before we load the configuration.
The hs_free_all() is added to release everything from tor_free_all().
Note that both functions do NOT handle v2 service subsystem but does handle
the common interface that both v2 and v3 needs such as the cache and
circuitmap.
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>
