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.
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.
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
a) this is 2009
b) niels and nick have been comaintainers for a while
c) saying "all rights reserved" when you then go on to explicitly
disclaim some rights is sheer cargo-cultism.
svn:r1065
Add an --enable-gcc-warnings option (lifted from Tor) to the configure script. When provided, and when we are using GCC, we enable a bunch of extra GCC warnings in the compiler. Also, make the code all build happily with these warnings.
svn:r553
In ANSI C, int func() is a function with unspecified arguments, whereas int func(void) is a function that takes no arguments. Using int func() to mean a function with no arguments is a C++ism, so let's not use or generate it.
svn:r395
