The old logging code was littered with places where we stored messages in
static char[] fields. This is fine in a single-threaded program, but if you
ever tried to log evdns messages from two threads at once, you'd hit a race.
This patch also refactors evdns's debug_ntop function into a more useful
evutil_sockaddr_port_format() function, with unit tests.
When searching is enabled, evdns may make multiple requests before
calling the user callback with the result. This is a problem because
the same evdns_request handle is not retained for each search request,
so the user cannot reliably cancel the request.
This patch attempts to ensure that evdns_request persists accross
search requests.
The EVUTIL_CLOSESOCKET() macro required you to include unistd.h in your
source for POSIX. We might as well turn it into a function: an extra
function call is going to be cheap in comparison with the system call.
We retain the EVUTIL_CLOSESOCKET() macro as an alias for the new
evutil_closesocket() function.
(commit message from email by Nick and Sebastian)
It looks like when we moved from one big inflight-requests list to an
n-heads structure, we didn't make evdns_base_free() free the array of
heads. This patch should fix that.
Found with valgrind
Once, for reasons that made sense at the time, we had evdns.c use its
own logging subsystem with two levels, "warn" and "debug". This leads
to problems, since setting a log handler for Libevent wouldn't actually
trap these messages, since they weren't on by default, and since some of
the warns should really be msgs.
This patch changes the default behavior of evdns.c to log to
event_(debugx,warnx,msgx) by default, and adds a new (internal-use-only)
log level of EVDNS_LOG_MSG. Programs that set a evdns logging
function will see no change. Programs that don't will now see evdns
warnings reported like other warnings.
Previously, evdns was at the mercy of the user for providing a good
entropy source; without one, it would be vulnerable to various
active attacks.
This patch adds a port of OpenBSD's arc4random() calls to Libevent
[port by Chris Davis], and wraps it up a little bit so we can use it
more safely.
The 'flags' argument made sense when passed to
evdns_(base_)?parse_resolv_conf when it said which parts of the
resolv.conf file to obey. But for evdns_set_option(), it was really
silly, since you wouldn't be calling evdns_set_option() unless you
actually wanted to set the option. Its meaning was basically, "set
this to DNS_OPTIONS_ALL unless you want a funny surprise."
evdns_base_set_option was new in 2.0.1-alpha, so we aren't committed
to keeping it source-compatible.
This patch fixes calls to the win32 api to explicitly call the char* versions
of the functions. This fixes build failures when libevent is built with the
UNICODE define.
It turns out that absolutely everything that was including
windows.h was doing so needlessly; our headers don't need it,
so we should just include winsock2.h (since that's where
struct timeval is defined).
Pre-2.0 code will use the old headers, which include windows.h
for them, so we aren't breaking source compatibility with 1.4.
This solves the bug where we were leaving WIN32_LEAN_AND_MEAN
defined, in roughly the same way that buying an automobile
solves the question of what to give your coachman for boxing
day.
The logic that prevented the first loop in this function from being
infinite was rather confusing and hard to follow. It seems to confuse
some automatic analysis tools as well as me. Let's try to replace it
with something more comprehensible.
I don't expect that many users will be so religious about calling
unassign, but we need to be so that it's at least possible to use
debug mode without eating memory.
Most of these should be unable to fail, since adding a timeout
generally always works. Still, it's better not to try to be "too
smart for our own good here."
There are some remaining event_add() calls that I didn't add checks
for; I've marked those with "XXXX" comments.
If the user sets a bind address to use for nameservers, and a
nameserver happens to be on 127.0.0.1, the nameserver will generally
fail. This patch alters this behavior so that the bind address is
only applied when the nameserver is on a non-loopback address.
This is harder than it might initially seem, since the proper filename
depends on what the admin has decided to call the windows system directory,
which for all we know might be Q:\tralfamidore\slartibartfast. And of course,
this being windows, there are twelve ways to do it, where you can pick a
nice one or a portable one, but not a really nice portable one.
The regular blocking evutil_getaddrinfo() already supported /etc/hosts
by falling back to getaddrinfo() or gethostbyname(). But
evdns_getaddrinfo() had no such facility. Now it does.
The data structure here isn't very clever. I guess people with huge
/etc/hosts files will either need to get out of the 1980s, or submit a
patch to this code so that it uses a hashtable instead of a linked
list.
Includes basic unit tests.
When we decide that a nameserver is down, we stop sending queries to
it, except to periodically probe it to see if it has come back up.
Our previous probe sechedule was an ad-hoc and hard-wired "10 seconds,
one minute, 5 minues, 15 minutes, 1 hour, 1 hour, 1 hour...". There
was nothing wrong with having it be ad-hoc, but making it hard-wired
served no good purpose.
Now the user can set the initial timeout via a new
"initial-probe-timeout:" option; future timeouts back off by a factor
of 3 on every failure to a maximum of 1 hour.
As a side-benefit, this lets us cut the runtime of the dns/retry test
from about 40 seconds to about 3 seconds. Faster unit tests are
always a good thing.
There were a couple of places in the code where we manually kept lock
counts to make sure we never accessed resources without holding a
lock, and that we never released a lock we didn't have. The
lock-debugging code already puts counts on _every_ lock when lock
debugging is enabled, so there is no need to keep these counts around
otherwise. This patch rewrites the ASSERT_FOO_LOCKED macros to all
use a common EVLOCK_ASSERT_LOCKED().
We also teach the lock debugging code to keep track of who exactly
holds each lock, so that EVLOCK_ASSERT_LOCKED() means "locked by this
thread."
Original message:
evdns contains a bug related to thread lock.
enable thread lock by evthread_use_pthreads() will cause successive
evdns_base_resolve_ipv4() (and other resolve functions i think) to
hang on EVDNS_LOCK(base) after one or several successful call to
evdns_base_resolve_ipv4().
Previously, our default lock model kind of assumed that every lock was
potentially a read-write lock. This was a poor choice, since
read-write locks are far more expensive than regular locks, and so the
lock API should only use them when we can actually take advantage of
them. Neither our pthreads or win32 lock implementation provided rw
locks.
Now that we have a way (not currently used!) to indicate that we
really want a read-write lock, we shouldn't actually say "lock this
for reading" or "lock this for writing" unless we mean it.
Previously, there was no good way to request different kinds of lock
(say, read/write vs writeonly or recursive vs nonrecursive), or for a
lock function to signal failure (which would be important for a
trylock mode).
This patch revises the lock API to be a bit more useful. The older
lock calls are still supported for now.
We also add a debugging mode to catch common errors in using the
locking APIs.
The entry points are evutil_getaddrinfo and evdns_getaddrinfo respectively.
There are fairly extensive unit tests.
I believe this code conforms to RFC3493 pretty closely, but there are
probably more issues. It should get tested on more platforms.
This code means we can dump the well-intentioned but weirdly-implemented
bufferevent_evdns and evutil_resolve code.
svn:r1537
This function, bufferevent_socket_connect_hostname() can either use
evdns to do the resolve, or use a new function (evutil_resolve) that
uses getaddrinfo or gethostbyname, like http.c does now.
This function is meant to eventually replace the hostname resolution mess in
http.c.
svn:r1496
