commit cb4cedae686bd227d42997840b3a6b0b3bc5e936 Author: Nick Mathewson nickm@torproject.org Date: Mon Oct 19 11:45:24 2020 -0400

Explain why we use "mark_as_used_for_origin_circuit" where we do

Also, explain why it's relevant for bootstrapping.

This is a comments-only patch. --- src/core/or/channel.c | 3 +++ src/core/or/channeltls.c | 5 ++++- src/core/or/circuitbuild.c | 5 +++++ src/feature/control/control_bootstrap.c | 11 ++++++++++- 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/core/or/channel.c b/src/core/or/channel.c index 0765f222c1..c163f53488 100644 --- a/src/core/or/channel.c +++ b/src/core/or/channel.c @@ -2447,6 +2447,9 @@ channel_get_for_extend,(const char *rsa_id_digest, if (matches_target) { ++n_inprogress_goodaddr; if (for_origin_circ) { + /* We were looking for a connection for an origin circuit; this one + * matches, so we'll note that we decided to use it for an origin + * circuit. */ channel_mark_as_used_for_origin_circuit(chan); } } diff --git a/src/core/or/channeltls.c b/src/core/or/channeltls.c index 2c52c07bb5..32723fed1e 100644 --- a/src/core/or/channeltls.c +++ b/src/core/or/channeltls.c @@ -365,7 +365,10 @@ channel_tls_handle_incoming(or_connection_t *orconn) * corresponding to the provided channel. * * This flag indicates that if the connection fails, it might be interesting - * to the bootstrapping subsystem. + * to the bootstrapping subsystem. (The bootstrapping system only cares about + * channels that we have tried to use for our own circuits. Other channels + * may have been launched in response to EXTEND cells from somebody else, and + * if they fail, it won't necessarily indicate a bootstrapping problem.) **/ void channel_mark_as_used_for_origin_circuit(channel_t *chan) diff --git a/src/core/or/circuitbuild.c b/src/core/or/circuitbuild.c index 225a0112f7..0b53a4cda8 100644 --- a/src/core/or/circuitbuild.c +++ b/src/core/or/circuitbuild.c @@ -591,6 +591,10 @@ circuit_handle_first_hop(origin_circuit_t *circ) log_info(LD_CIRC,"connect to firsthop failed. Closing."); return -END_CIRC_REASON_CONNECTFAILED; } + /* We didn't find a channel, but we're launching one for an origin + * circuit. (If we decided not to launch a channel, then we found at + * least one once good in-progress channel use for this circuit, and + * marked it in channel_get_for_extend().) */ channel_mark_as_used_for_origin_circuit(n_chan); circuit_chan_publish(circ, n_chan); } @@ -604,6 +608,7 @@ circuit_handle_first_hop(origin_circuit_t *circ) } else { /* it's already open. use it. */ tor_assert(!circ->base_.n_hop); circ->base_.n_chan = n_chan; + /* We found a channel, and we're using it for an origin circuit. */ channel_mark_as_used_for_origin_circuit(n_chan); circuit_chan_publish(circ, n_chan); log_debug(LD_CIRC,"Conn open for %s. Delivering first onion skin.", diff --git a/src/feature/control/control_bootstrap.c b/src/feature/control/control_bootstrap.c index cca2a81b1f..d6dfdad94e 100644 --- a/src/feature/control/control_bootstrap.c +++ b/src/feature/control/control_bootstrap.c @@ -348,8 +348,17 @@ control_event_bootstrap_prob_or, (const char *warn, int reason, { int dowarn = 0;

- if (! or_conn->potentially_used_for_bootstrapping) + if (! or_conn->potentially_used_for_bootstrapping) { + /* We never decided that this channel was a good match for one of our + * origin_circuit_t objects. That means that we probably launched it + * for somebody else, most likely in response to an EXTEND cell. + * + * Since EXTEND cells can contain arbitrarily broken descriptions of + * relays, a failure on this connection here won't necessarily indicate a + * bootstrapping problem. + */ return; + }

if (or_conn->have_noted_bootstrap_problem) return;