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(backport to 0.2.0.x) Fix for bug 797 (by arma, with tweaks): always use create_fast for circuits where we do not know an onion key. 

svn:r16943
This commit is contained in:
Nick Mathewson 2008-09-23 20:13:43 +00:00
parent c4397f6257
commit 9d296f7701
3 changed files with 23 additions and 25 deletions
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3
ChangeLog
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@ -3,6 +3,9 @@ Changes in version 0.2.0.32 - 2008-??-??
- Fix several infrequent memory leaks spotted by Coverity.
- When testing for libevent functions, set the LDFLAGS variable
correctly. (Found by Riastradh.)
- Avoid a bug where the FistFirstHopPK 0 option would keep Tor from
bootstrapping with tunneled directory connections. Bugfix on
0.1.2.5-alpha. Fixes bug 797.
Changes in version 0.2.0.31 - 2008-09-03

13
doc/tor.1.in
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@ -663,11 +663,14 @@ resolved. This helps trap accidental attempts to resolve URLs and so on.
.LP
.TP
\fBFastFirstHopPK \fR\fB0\fR|\fB1\fR\fP
When this option is enabled and we aren't running as a server, Tor
skips the public key step for the first hop of creating circuits. This is
safe since we have already used TLS to authenticate the server and to
establish forward-secure keys. Turning this option off makes circuit
building slower.
When this option is disabled, Tor uses the public key step for the first
hop of creating circuits. Skipping it is generally safe since we have
already used TLS to authenticate the relay and to establish forward-secure
keys. Turning this option off makes circuit building slower.
Note that Tor will always use the public key step for the first hop if
it's operating as a relay, and it will never use the public key step if
it doesn't yet know the onion key of the first hop.
(Default: 1)
.LP
.TP

32
src/or/circuitbuild.c
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@ -541,23 +541,20 @@ inform_testing_reachability(void)
return 1;
}
/** Return true iff we should send a create_fast cell to build a circuit
* starting at <b>router</b>. (If <b>router</b> is NULL, we don't have
* information on the router, so assume true.) */
/** Return true iff we should send a create_fast cell to start building a given
* circuit */
static INLINE int
should_use_create_fast_for_router(routerinfo_t *router,
origin_circuit_t *circ)
should_use_create_fast_for_circuit(origin_circuit_t *circ)
{
or_options_t *options = get_options();
tor_assert(circ->cpath);
tor_assert(circ->cpath->extend_info);
if (!options->FastFirstHopPK) /* create_fast is disabled */
return 0;
if (router && router->platform &&
!tor_version_as_new_as(router->platform, "0.1.0.6-rc")) {
/* known not to work */
return 0;
}
if (server_mode(options) && circ->cpath->extend_info->onion_key) {
if (!circ->cpath->extend_info->onion_key)
return 1; /* our hand is forced: only a create_fast will work. */
if (!options->FastFirstHopPK)
return 0; /* we prefer to avoid create_fast */
if (server_mode(options)) {
/* We're a server, and we know an onion key. We can choose.
* Prefer to blend in. */
return 0;
@ -593,14 +590,9 @@ circuit_send_next_onion_skin(origin_circuit_t *circ)
log_debug(LD_CIRC,"First skin; sending create cell.");
router = router_get_by_digest(circ->_base.n_conn->identity_digest);
fast = should_use_create_fast_for_router(router, circ);
if (!fast && !circ->cpath->extend_info->onion_key) {
log_warn(LD_CIRC,
"Can't send create_fast, but have no onion key. Failing.");
return - END_CIRC_REASON_INTERNAL;
}
fast = should_use_create_fast_for_circuit(circ);
if (!fast) {
/* We are an OR, or we are connecting to an old Tor: we should
/* We are an OR and we know the right onion key: we should
* send an old slow create cell.
*/
cell_type = CELL_CREATE;