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Fix If-Modified-Since in rapidly updating Tor networks

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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.
This commit is contained in:
teor 2014-12-20 21:59:17 +11:00
parent 1ee41b3eef
commit 8a8797f1e4
2 changed files with 30 additions and 4 deletions
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7
changes/bug13963-decrease-if-modified-since-delay Normal file
View File

@ -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.

27
src/or/directory.c
View File

@ -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. */