At this commit, the tor main loop solves it. We might consider moving
this to the CPU pool at some point.
Signed-off-by: David Goulet <dgoulet@torproject.org>
We discovered two cases where edge connections can stall during testing:
1. Due to final data sitting in the edge inbuf when it was resumed
2. Due to flag synchronization between the token bucket and XON/XOFF
The first issue has always existed in C-Tor, but we were able to tickle it
in scp testing. If the last data from the protocol is able to fit in the
inbuf, but not large enough to send, if an XOFF or connection block comes in
at exactly that point, when the edge connection resumes, there will be no
data to read from the socket, but the inbuf can just sit there, never
draining.
We noticed the second issue along the way to finding the first. It seems
wrong, but it didn't seem to affect anything in practice.
These are extremely rare in normal operation, but with conflux, XON/XOFF
activity is more common, so we hit these.
Signed-off-by: David Goulet <dgoulet@torproject.org>
In https://gitlab.torproject.org/tpo/core/tor/-/issues/40623, we changed the
DESTROY propogation to ensure memory was freed quickly at relays. This was a
good move, but it exacerbates the condition where a stream is closed on a
circuit, and then it is immediately closed because it is dirty. This creates a
race between the DESTROY and the last data sent on the stream. This race is
visible in shadow, and does happen.
This could be backported. A better solution to these kinds of problems is to
create an ENDED cell, and not close any circuits until the ENDED comes back.
But this will also require thinking, since this ENDED cell can also get lost,
so some kind of timeout may be needed either way. The ENDED cell could just
allow us to have much longer timeouts for this case.
This adds utility functions to help stream block decisions, as well as cpath
layer_hint checks for stream cell acceptance, and syncing stream lists
for conflux circuits.
These functions are then called throughout the codebase to properly manage
conflux streams.
Streams can get blocked on a circuit in two ways:
1. When the circuit package window is full
2. When the channel's cell queue is too high
Conflux needs to decouple stream blocking from both of these conditions,
because streams can continue on another circuit, even if the primary circuit
is blocked for either of these cases.
However, both conflux and congestion control need to know if the channel's
cell queue hit the highwatermark and is still draining, because this condition
is used by those components, independent of stream state.
Therefore, this commit renames the 'streams_blocked_on_chan' variable to
signify that it refers to the cell queue state, and also refactors the actual
stream blocking bits out, so they can be handled separately if conflux is
present.
Because circuit-level sendmes are sent before relay data cells are processed,
we can safely move this to before the conflux decision. In this way,
regardless of conflux being negotiated, we still send sendmes as soon as data
cells are recieved. This avoids introducing conflux queue delay into RTT
measurement, which is important for measuring actual circuit capacity.
The circuit-level tracking must happen inside the call to send a data cell,
since that call now chooses a circuit to send on. Turns out, we were already
doing this kind of here, but only for the digest. Now we do both things here.
We use the oldest-circ-first method here, since that seems good for conflux:
queues could briefly spike, but the bad case is if they are maliciously
bloated to stick around for a long time.
The tradeoff here is that it is possible to kill old circuits on a relay
quickly, but that has always been the case with this algorithm choice.
Signed-off-by: David Goulet <dgoulet@torproject.org>
This adds 2 histogram metrics for hidden services:
* `tor_hs_rend_circ_build_time` - the rendezvous circuit build time in milliseconds
* `tor_hs_intro_circ_build_time` - the introduction circuit build time in milliseconds
The text representation representation of the new metrics looks like this:
```
# HELP tor_hs_rend_circ_build_time The rendezvous circuit build time in milliseconds
# TYPE tor_hs_rend_circ_build_time histogram
tor_hs_rend_circ_build_time_bucket{onion="<elided>",le="1000.00"} 2
tor_hs_rend_circ_build_time_bucket{onion="<elided>",le="5000.00"} 10
tor_hs_rend_circ_build_time_bucket{onion="<elided>",le="10000.00"} 10
tor_hs_rend_circ_build_time_bucket{onion="<elided>",le="30000.00"} 10
tor_hs_rend_circ_build_time_bucket{onion="<elided>",le="60000.00"} 10
tor_hs_rend_circ_build_time_bucket{onion="<elided>",le="+Inf"} 10
tor_hs_rend_circ_build_time_sum{onion="<elided>"} 10824
tor_hs_rend_circ_build_time_count{onion="<elided>"} 10
# HELP tor_hs_intro_circ_build_time The introduction circuit build time in milliseconds
# TYPE tor_hs_intro_circ_build_time histogram
tor_hs_intro_circ_build_time_bucket{onion="<elided>",le="1000.00"} 0
tor_hs_intro_circ_build_time_bucket{onion="<elided>",le="5000.00"} 6
tor_hs_intro_circ_build_time_bucket{onion="<elided>",le="10000.00"} 6
tor_hs_intro_circ_build_time_bucket{onion="<elided>",le="30000.00"} 6
tor_hs_intro_circ_build_time_bucket{onion="<elided>",le="60000.00"} 6
tor_hs_intro_circ_build_time_bucket{onion="<elided>",le="+Inf"} 6
tor_hs_intro_circ_build_time_sum{onion="<elided>"} 9843
tor_hs_intro_circ_build_time_count{onion="<elided>"} 6
```
Signed-off-by: Gabriela Moldovan <gabi@torproject.org>
This adds a `reason` label to the `hs_intro_rejected_intro_req_count` and
`hs_rdv_error_count` metrics introduced in #40755.
Metric look up and intialization is now more a bit more involved. This may be
fine for now, but it will become unwieldy if/when we add more labels (and as
such will need to be refactored).
Also, in the future, we may want to introduce finer grained `reason` labels.
For example, the `invalid_introduce2` label actually covers multiple types of
errors that can happen during the processing of an INTRODUCE2 cell (such as
cell parse errors, replays, decryption errors).
Signed-off-by: Gabriela Moldovan <gabi@torproject.org>
This introduces a couple of new service side metrics:
* `hs_intro_rejected_intro_req_count`, which counts the number of introduction
requests rejected by the hidden service
* `hs_rdv_error_count`, which counts the number of rendezvous errors as seen by
the hidden service (this number includes the number of circuit establishment
failures, failed retries, end-to-end circuit setup failures)
Closes#40755. This partially addresses #40717.
Signed-off-by: Gabriela Moldovan <gabi@torproject.org>
