commit 8a8797f1e45e6124ac93e3a8fb277b5758d7c935 Author: teor teor2345@gmail.com Date: Sat Dec 20 21:59:17 2014 +1100

Fix If-Modified-Since in rapidly updating Tor networks

When V3AuthVotingInterval is low, decrease the delay on the If-Modified-Since header passed to directory servers. This allows us to obtain consensuses promptly when the consensus interval is very short.

This assists in bootstrapping a testing Tor network.

Fixes bugs 13718 & 13963. --- changes/bug13963-decrease-if-modified-since-delay | 7 ++++++ src/or/directory.c | 27 ++++++++++++++++++--- 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/changes/bug13963-decrease-if-modified-since-delay b/changes/bug13963-decrease-if-modified-since-delay new file mode 100644 index 0000000..6237144 --- /dev/null +++ b/changes/bug13963-decrease-if-modified-since-delay @@ -0,0 +1,7 @@ + o Minor bugfixes: + - When V3AuthVotingInterval is low, decrease the delay on the + If-Modified-Since header passed to directory servers. + This allows us to obtain consensuses promptly when the consensus + interval is very short. + This assists in bootstrapping a testing Tor network. + Fixes bugs 13718 & 13963. diff --git a/src/or/directory.c b/src/or/directory.c index cca4b54..b88c9d9 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -433,18 +433,33 @@ directory_get_from_dirserver(uint8_t dir_purpose, uint8_t router_purpose, if (resource) flav = networkstatus_parse_flavor_name(resource);

+ /* DEFAULT_IF_MODIFIED_SINCE_DELAY is 1/20 of the default consensus + * period of 1 hour. + */ +#define DEFAULT_IF_MODIFIED_SINCE_DELAY (180) if (flav != -1) { /* IF we have a parsed consensus of this type, we can do an * if-modified-time based on it. */ v = networkstatus_get_latest_consensus_by_flavor(flav); - if (v) - if_modified_since = v->valid_after + 180; + if (v) { + /* In networks with particularly short V3AuthVotingIntervals, + * ask for the consensus if it's been modified since half the + * V3AuthVotingInterval of the most recent consensus. */ + time_t ims_delay = DEFAULT_IF_MODIFIED_SINCE_DELAY; + if (v->fresh_until > v->valid_after + && ims_delay > (v->fresh_until - v->valid_after)/2) { + ims_delay = (v->fresh_until - v->valid_after)/2; + } + if_modified_since = v->valid_after + ims_delay; + } } else { /* Otherwise it might be a consensus we don't parse, but which we * do cache. Look at the cached copy, perhaps. */ cached_dir_t *cd = dirserv_get_consensus(resource); + /* We have no method of determining the voting interval from an + * unparsed consensus, so we use the default. */ if (cd) - if_modified_since = cd->published + 180; + if_modified_since = cd->published + DEFAULT_IF_MODIFIED_SINCE_DELAY; } }

@@ -2258,6 +2273,7 @@ write_http_status_line(dir_connection_t *conn, int status, log_warn(LD_BUG,"status line too long."); return; } + log_debug(LD_DIRSERV,"Wrote status 'HTTP/1.0 %d %s'", status, reason_phrase); connection_write_to_buf(buf, strlen(buf), TO_CONN(conn)); }

@@ -2554,8 +2570,11 @@ directory_handle_command_get(dir_connection_t *conn, const char *headers, if ((header = http_get_header(headers, "If-Modified-Since: "))) { struct tm tm; if (parse_http_time(header, &tm) == 0) { - if (tor_timegm(&tm, &if_modified_since)<0) + if (tor_timegm(&tm, &if_modified_since)<0) { if_modified_since = 0; + } else { + log_debug(LD_DIRSERV, "If-Modified-Since is '%s'.", escaped(header)); + } } /* The correct behavior on a malformed If-Modified-Since header is to * act as if no If-Modified-Since header had been given. */