Apple is supposed to decorate their function declarations with
macros to indicate which OSX version introduced them, so that you
can tell the compiler that you want to build against certain
versions of OSX.  But they forgot to do that for clock_gettime() and
getentropy(), both of which they introduced in 10.12.

This patch adds a kludge to the configure.ac script where, if we
detect that we are targeting OSX 10.11 or earlier, we don't even probe
to see if the two offending functions are present.

Closes ticket 20235.

In our code to write public keys to a string, for some unfathomable
reason since 253f0f16, we would allocate a memory BIO, then
set the NOCLOSE flag on it, extract its memory buffer, and free it.
Then a little while later we'd free the memory buffer with
BUF_MEM_free().

As of openssl 1.1 this doesn't work any more, since there is now a
BIO_BUF_MEM structure that wraps the BUF_MEM structure.  This
BIO_BUF_MEM doesn't get freed in our code.

So, we had a memory leak!

Is this an openssl bug?  Maybe.  But our code was already pretty
silly.  Why mess around with the NOCLOSE flag here when we can just
keep the BIO object around until we don't need the buffer any more?

Fixes bug 20553; bugfix on 0.0.2pre8

fixes bug 20551; bugfix on 0.2.1.1-alpha

Nick Mathewson authored 8 years ago and Roger Dingledine committed 8 years ago

Fixes bug 19969; bugfix on b1d56fc5.  We can fix this some more in
later Tors, but for now, this is probably the simplest fix possible.

This is a belt-and-suspenders fix, where the earlier fix ("Ask
event_base_loop to finish when we add a pending stream") aims to respond
to new streams as soon as they arrive, and this one aims to make sure
that we definitely respond to all of the streams.

Fixes bug 19969; bugfix on b1d56fc5. We can fix this some more in
later Tors, but for now, this is probably the right fix for us.

no actual changes

This helps protect against bugs where any part of a buf_t's memory
is passed to a function that expects a NUL-terminated input.

It also closes TROVE-2016-10-001 (aka bug 20384).

Not telling the cmux would sometimes cause an assertion failure in
relay.c when we tried to get an active circuit and found an "active"
circuit with no cells.

Additionally, replace that assert with a test and a log message.

Fix for bug 20203. This is actually probably a bugfix on
0.2.8.1-alpha, specifically my code in 8b4e5b7e where I
made circuit_mark_for_close_() do less in order to simplify our call
graph. Thanks to "cypherpunks" for help diagnosing.

For a brief moment in networkstatus_set_current_consensus(), the old
consensus has been freed, but the node_t objects still have dead
pointers to the routerstatus_t objects within it.  During that
interval, we absolutely must not do anything that would cause Tor to
look at those dangling pointers.

Unfortunately, calling the (badly labeled!) current_consensus macro
or anything else that calls into we_use_microdescriptors_for_circuits(),
can make us look at the nodelist.

The fix is to make sure we identify the main consensus flavor
_outside_ the danger zone, and to make the danger zone much much
smaller.

Fixes bug 20103.  This bug has been implicitly present for AGES; we
just got lucky for a very long time.  It became a crash bug in
0.2.8.2-alpha when we merged 35bbf2e4 to make
find_dl_schedule start looking at the consensus, and 4460feaf
which made node_get_all_orports less (accidentally) tolerant of
nodes with a valid ri pointer but dangling rs pointer.