There is a bug causing busy loops in Libevent and infinite loops in
the Shadow simulator. A connection that is marked for close, wants
to flush, is held open to flush, but is rate limited (the token
bucket is empty) triggers the bug.
This commit fixes the bug. Details are below.
This currently happens on read and write callbacks when the active
socket is marked for close. In this case, Tor doesn't actually try
to complete the read or write (it returns from those methods when
marked), but instead tries to clear the connection with
conn_close_if_marked(). Tor will not close a marked connection that
contains data: it must be flushed first. The bug occurs when this
flush operation on the marked connection can not occur because the
connection is rate-limited (its write token bucket is empty).
The fix is to detect when rate limiting is preventing a marked
connection from properly flushing. In this case, it should be
flagged as read/write_blocked_on_bandwidth and the read/write events
de-registered from Libevent. When the token bucket gets refilled, it
will check the associated read/write_blocked_on_bandwidth flag, and
add the read/write event back to Libevent, which will cause it to
fire. This time, it will be properly flushed and closed.
The reason that both read and write events are both de-registered
when the marked connection can not flush is because both result in
the same behavior. Both read/write events on marked connections will
never again do any actual reads/writes, and are only useful to
trigger the flush and close the connection. By setting the
associated read/write_blocked_on_bandwidth flag, we ensure that the
event will get added back to Libevent, properly flushed, and closed.
Why is this important? Every Shadow event occurs at a discrete time
instant. If Tor does not properly deregister Libevent events that
fire but result in Tor essentially doing nothing, Libevent will
repeatedly fire the event. In Shadow this means infinite loop,
outside of Shadow this means wasted CPU cycles.
This is a feature removal: we no longer fake any ciphersuite other
than the not-really-standard SSL_RSA_FIPS_WITH_3DES_EDE_CBC_SHA
(0xfeff). This change will let servers rely on our actually
supporting what we claim to support, and thereby let Tor migrate to
better TLS ciphersuites.
As a drawback, Tor instances that use old openssl versions and
openssl builds with ciphers disabled will no longer give the
"firefox" cipher list.
Manually removed range 0.116.0.0 to 0.119.255.255 which Maxmind says is
assigned to AT. This is very likely a bug in their database, because
0.0.0.0/8 is a reserved range.
From what I can tell, this configuration is usually a mistake, and
leads people to think that all their traffic is getting proxied when
in fact practically none of it is. Resolves the issue behind "bug"
4663.
The function is not guaranteed to NUL-terminate its output. It
*is*, however, guaranteed not to generate more than two bytes per
multibyte character (plus terminating nul), so the general approach
I'm taking is to try to allocate enough space, AND to manually add a
NUL at the end of each buffer just in case I screwed up the "enough
space" thing.
Fixes bug 5909.
This feature can make Tor relays less identifiable by their use of the
mod_ssl DH group, but at the cost of some usability (#4721) and bridge
tracing (#6087) regressions.
We should try to turn this on by default again if we find that the
mod_ssl group is uncommon and/or we move to a different DH group size
(see #6088). Before we can do so, we need a fix for bugs #6087 and
Resolves ticket #5598 for now.
These include:
- Having a weird in_addr that can't be initialized with {0}
- Needing INVALID_HANDLE_VALUE instead of -1 for file handles.
- Having a weird dependent definition for struct stat.
- pid is signed, not unsigned.
These stats are currently discarded, but we might as well
hard-disable them on bridges, to be clean.
Fix for bug 5824; bugfix on 0.2.1.17-rc.
Patch originally by Karsten Loesing.
Also, try to resolve some doxygen issues. First, define a magic
"This is doxygen!" macro so that we take the correct branch in
various #if/#else/#endifs in order to get the right documentation.
Second, add in a few grouping @{ and @} entries in order to get some
variables and fields to get grouped together.
This code shouldn't have any effect in 0.2.3, since we already accept
(and handle) data received while we are expecting a renegotiation.
(That's because the 0.2.3.x handshake _does_ have data there instead of
the renegotiation.)
I'm leaving it in anyway, since if it breaks anything, we'll want it
broken in master too so we can find out about it. I added an XXX023
comment so that we can come back later and fix that.
This fixes a DoS issue where a client could send so much data in 5
minutes that they exhausted the server's RAM. Fix for bug 5934 and
6007. Bugfix on 0.2.0.20-rc, which enabled the v2 handshake.
This fixes a warning in efb8a09f, where Debain Lenny's GCC doesn't get
that
for (i=0; i<3; ++i) {
const char *p;
switch(i) {
case 0:
p="X"; break;
case 1:
p="Y"; break;
case 2:
p="Z"; break;
}
printf("%s\n", p);
}
will never try to print an uninitialezed value.
Found by buildbots. Bug in no released versions of Tor.
It appears that when OpenSSL negotiates a 1.1 or 1.2 connection, and it
decides to renegotiate, the client will send a record with version "1.0"
rather than with the current TLS version. This would cause the
connection to fail whenever both sides had OpenSSL 1.0.1, and the v2 Tor
handshake was in use.
As a workaround, disable TLS 1.1 and TLS 1.2. When a later version of
OpenSSL is released, we can make this conditional on running a fixed
version of OpenSSL.
Alternatively, we could disable TLS 1.1 and TLS 1.2 only on the client
side. But doing it this way for now means that we not only fix TLS with
patched clients; we also fix TLS when the server has this patch and the
client does not. That could be important to keep the network running
well.
Fixes bug 6033.
This solves bug 5283, where client traffic could get sent over the
same circuit as an anonymized connection to a directory, even if
that circuit used an exit node unsuitable for clients. By marking
the directory connection as needs_internal, we ensure that the
(non-internal!) client-traffic connection won't be sent over the
same circuit.
Conflicts:
src/test/test_util.c
Merge the unit tests; I added some when I did this branch against
0.2.2, and then the test format changed and master added more tests.
Conflicts:
src/common/compat.h
Conflict was between replacement of MS_WINDOWS with _WIN32 in
master, and with removal of file_handle from tor_mmap_t struct in
close_file_mapping branch (for bug 5951 fix).
It turns out that if you set the third argument of
__attribute__(format) to 0, GCC and Clang will check the format
argument without expecting to find variadic arguments. This is the
correct behavior for vsnprintf, vasprintf, and vscanf.
I'm hoping this will fix bug 5969 (a clang warning) by telling clang that
the format argument to tor_vasprintf is indeed a format string.
On Windows, getsockname() on a nonblocking apparently won't work
until the connection is done connecting. On XP, it seems to fail by
reporting success and declaring that your address is INADDR_ANY. On the
Win8 preview, though, it fails more loudly and says WSAEINVAL.
Fix for bug 5374; bugfix on 0.1.1.14-alpha.
The parent of "/foo" is "/"; and "/" is its own parent.
This would cause Tor to fail if you tried to have a PF_UNIX control
socket in the root directory. That would be a stupid thing to do
for other reasons, but there's no reason to fail like _this_.
Bug found by Esteban Manchado Velázquez. Fix for bug 5089; bugfix on
Tor 0.2.2.26-beta. Unit test included.
Roger explains at
http://archives.seul.org/tor/talk/Nov-2011/msg00209.html :
"If you list your bridge as part of your family in the relay
descriptor, then everybody can learn your bridge fingerprint, and
they can look up your bridge's descriptor (and thus location) at
the bridge directory authority."
Now, we can't stop relays from listing bridges, but we can warn when
we notice a bridge listing anybody, which might help some.
This fixes bug 4657; it's a fix on 0.2.0.3-alpha, where bridges were
first introduced.
