Fixes bug 4259, bugfix on 0.2.2.25-alpha. Bugfix by "Tey'".
Original message by submitter:
Changing nodes restrictions using a controller while Tor is doing
DNS resolution could makes Tor crashes (on WinXP at least). The
problem can be repeated by trying to reach a non-existent domain
using Tor:
curl --socks4a 127.0.0.1:9050 inexistantdomain.ext
.. and changing the ExitNodes parameter through the control port
before Tor returns a DNS resolution error (of course, the following
command won't work directly if the control port is password
protected):
echo SETCONF ExitNodes=TinyTurtle | nc -v 127.0.0.1 9051
Using a non-existent domain is needed to repeat the issue so that
Tor takes a few seconds for resolving the domain (which allows us to
change the configuration). Tor will crash while processing the
configuration change.
The bug is located in the addressmap_clear_excluded_trackexithosts
method which iterates over the entries of the addresses map in order
to check whether the changes made to the configuration will impact
those entries. When a DNS resolving is in progress, the new_adress
field of the associated entry will be set to NULL. The method
doesn't expect this field to be NULL, hence the crash.
Previously, we would treat an intro circuit failure as a timeout iff the
circuit failed due to a mismatch in relay identity keys. (Due to a bug
elsewhere, we only recognize relay identity-key mismatches on the first
hop, so this isn't as bad as it could have been.)
Bugfix on commit eaed37d14c, not yet in any
release.
It's too risky to have a function where if you leave one parameter
NULL, it splits up address:port strings, but if you set it, it does
hostname resolution.
Under the new convention, having a tor_addr.*lookup function that
doesn't do hostname resolution is too close for comfort.
I used this script here, and have made no other changes.
s/tor_addr_parse_reverse_lookup_name/tor_addr_parse_PTR_name/g;
s/tor_addr_to_reverse_lookup_name/tor_addr_to_PTR_name/g;
Now let's have "lookup" indicate that there can be a hostname
resolution, and "parse" indicate that there wasn't. Previously, we
had one "lookup" function that did resolution; four "parse" functions,
half of which did resolution; and a "from_str()" function that didn't
do resolution. That's confusing and error-prone!
The code changes in this commit are exactly the result of this perl
script, run under "perl -p -i.bak" :
s/tor_addr_port_parse/tor_addr_port_lookup/g;
s/parse_addr_port(?=[^_])/addr_port_lookup/g;
s/tor_addr_from_str/tor_addr_parse/g;
This patch leaves aton and pton alone: their naming convention and
behavior is is determined by the sockets API.
More renaming may be needed.
Right now we can take the digests only of an RSA key, and only expect to
take the digests of an RSA key. The old tor_cert_get_id_digests() would
return a good set of digests for an RSA key, and an all-zero one for a
non-RSA key. This behavior is too error-prone: it carries the risk that
we will someday check two non-RSA keys for equality and conclude that
they must be equal because they both have the same (zero) "digest".
Instead, let's have tor_cert_get_id_digests() return NULL for keys we
can't handle, and make its callers explicitly test for NULL.
Our keys and x.509 certs are proliferating here. Previously we had:
An ID cert (using the main ID key), self-signed
A link cert (using a shorter-term link key), signed by the ID key
Once proposal 176 and 179 are done, we will also have:
Optionally, a presentation cert (using the link key),
signed by whomever.
An authentication cert (using a shorter-term ID key), signed by
the ID key.
These new keys are managed as part of the tls context infrastructure,
since you want to rotate them under exactly the same circumstances,
and since they need X509 certificates.
