Right now this is only needed for test_util_format_time_interval, so
define it as a static function.  We can move it into compat later if
we need to.

 1. The test that adds things to the cache needs to set the clock back so
    that the descriptors it adds are valid.

 2. We split ROUTER_NOT_NEW into ROUTER_TOO_OLD, so that we can
    distinguish "already had it" from "rejected because of old published
    date".

 3. We make extrainfo_insert() return a was_router_added_t, and we
    make its caller use it correctly.  This is probably redundant with
    the extrainfo_is_bogus flag.

Suggested by Andrea in her review of 11243.

These tests make sure that entries are actually marked
undownloadable as appropriate.

We didn't really have test coverage for these parsing functions, so
I went and made some.  These tests also verify that the parsing
functions set the list of invalid digests correctly.

One pain point in evolving the Tor design and implementing has been
adding code that makes clients reject directory documents that they
previously would have accepted, if those descriptors actually exist.
When this happened, the clients would get the document, reject it,
and then decide to try downloading it again, ad infinitum.  This
problem becomes particularly obnoxious with authorities, since if
some authorities accept a descriptor that others don't, the ones
that don't accept it would go crazy trying to re-fetch it over and
over. (See for example ticket #9286.)

This patch tries to solve this problem by tracking, if a descriptor
isn't parseable, what its digest was, and whether it is invalid
because of some flaw that applies to the portion containing the
digest.  (This excludes RSA signature problems: RSA signatures
aren't included in the digest.  This means that a directory
authority can still put another directory authority into a loop by
mentioning a descriptor, and then serving that descriptor with an
invalid RSA signatures.  But that would also make the misbehaving
directory authority get DoSed by the server it's attacking, so it's
not much of an issue.)

We already have a mechanism to mark something undownloadable with
downloadstatus_mark_impossible(); we use that here for
microdescriptors, extrainfos, and router descriptors.

Unit tests to follow in another patch.

Closes ticket #11243.

Fix an instance of integer overflow in format_time_interval() when
taking the absolute value of the supplied signed interval value.
Fixes bug 13393.

Create unit tests for format_time_interval().

The versions which this function would keep from getting the guard
flag are already blocked by the minimum version check.

Closes 13152.

Merge remote-tracking branches 'teor/issue-13161-test-network' and 'teor/issue-13161-TestingDirAuthVoteExit'

Bitwise check for the BRIDGE_DIRINFO flag, rather than checking for
equality.

Fixes a (potential) bug where directories offering BRIDGE_DIRINFO,
and some other flag (i.e. microdescriptors or extrainfo),
would be ignored when looking for bridge directories.

Final fix in series for bug 13163.

Document usage of the NO_DIRINFO and ALL_DIRINFO flags clearly in functions
which take them as arguments. Replace 0 with NO_DIRINFO in a function call
for clarity.

Seeks to prevent future issues like 13163.

Stop using the default authorities in networks which provide both
AlternateDirAuthority and AlternateBridgeAuthority.

This bug occurred due to an ambiguity around the use of NO_DIRINFO.
(Does it mean "any" or "none"?)

Partially fixes bug 13163.

Preserve previous semantics of src/test/test-network.sh by exiting with
the exit status of chutney verify, even though the latest version ends
with chutney stop.

If (GNU) Make 3.81 is running processes in parallel using -j2 (or more),
it waits until all descendent processes have exited before it returns to
the shell.

When a command like "make -j2 test-network" is run, this means that
test-network.sh apparently hangs until it either make is forcibly
terminated, or all the chutney-launched tor processes have exited.

A workaround is to use make without -j, or make -j1 if there is an
existing alias to "make -jn" in the shell.

We resolve this bug in tor by using "chutney stop" after "chutney verify"
in test-network.sh.

Also, make sure we will compile correctly on systems where they
finally rip it out.

Fixes issue #13325.  Caused by this openbsd commit:

   ​http://marc.info/?l=openbsd-cvs&m=140768179627976&w=2

Reported by Fredzupy.

Add a --delay option to test-network.sh, which configures the delay before
the chutney network tests for data transmission. The default remains at
18 seconds if the argument isn't specified.

Apparently we should be using bootstrap status for this (eventually).

Partially implements ticket 13161.

The default shell on OS X is bash, which has a builtin echo. When called
in "sh" mode, this echo does not accept "-n". This patch uses "/bin/echo -n"
instead.

Partially fixes issue 13161.

Add the TestingDirAuthVoteExit option, a list of nodes to vote Exit for,
regardless of their uptime, bandwidth, or exit policy.

TestingTorNetwork must be set for this option to have any effect.

Works around an issue where authorities would take up to 35 minutes to
give nodes the Exit flag in a test network, despite short consensus
intervals. Partially implements ticket 13161.

Closes 11582; patch from "ra".

Fixes bug 13295; bugfix on 0.2.5.3-alpha.

The alternative here is to call crypto_global_init() from tor-resolve,
but let's avoid linking openssl into tor-resolve for as long as we
can.