commit 5149a07d896e212655992468dbb1edc980c9d0d2 Author: teor (Tim Wilson-Brown) teor2345@gmail.com Date: Sat Oct 3 22:44:35 2015 +0200
fixup name the right function in 210 --- .../210-faster-headless-consensus-bootstrap.txt | 27 ++++++++++++-------- 1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/proposals/210-faster-headless-consensus-bootstrap.txt b/proposals/210-faster-headless-consensus-bootstrap.txt index d527c2c..8e3cc69 100644 --- a/proposals/210-faster-headless-consensus-bootstrap.txt +++ b/proposals/210-faster-headless-consensus-bootstrap.txt @@ -154,23 +154,30 @@ Implementation Notes: Code Modifications if the purpose is DIR_PURPOSE_FETCH_CONSENSUS and there is no valid (reasonably live) consensus. We can make multiple connections from update_consensus_networkstatus_downloads(), as the sockets are non-blocking. - [ XXX - is this true for all platforms? ] + [ XXX - is this socket actually non-blocking for all platforms? ] As long as we can tolerate a timer resolution of ~1 second (due to the use of time_t), this requires no additional timers or callbacks. We can make 1 - connection for each schedule per second, for a total of 2 per second, or 4 - per second if the IPv4 and IPv6 schedules are implemented separately. + connection for each schedule per second, for a total of 2 per second.
update_consensus_networkstatus_downloads() would also check the list of pending connections and, if it is 10 or greater, skip the connection attempt, and leave the retry time constant.
- The code in directory_initiate_command_rend() or - connection_dir_finished_connecting() would need to be altered to check that - we are not already downloading the consensus. If we’re not, then call - directory_send_command() to download the consensus, and close any other - pending consensus dircons. (We may still want to check our clock against an - authority by allowing a TLS connection to complete, then immediately closing - it.) + The code in connection_dir_finished_connecting() would need to be altered to + check that we are not already downloading the consensus. If we’re not, then + call directory_send_command() to download the consensus, and close any other + pending consensus dircons. Since we want to check our clock against an + authority at least once per run, we instead mark authority connections so + they only request a HTTP HEAD, and use the first date header we see to + detect if the client’s clock is skewed. + [ XXX - does Tor support HTTP HEAD? ] + + We might also need to make similar changes in authority_certs_fetch_missing(), + as we can’t use a consensus until we have enough authority certificates. + However, Tor already makes multiple requests (one per certificate), and only + needs a majority of certificates to validate a consensus. Therefore, we will + only need to modify authority_certs_fetch_missing() if clients download a + consensus, then end up getting stuck downloading certificates.
Reliability Analysis