sometimes circuit_get_open_circ_or_launch() can return 0 but not
return a circuit, e.g. because too many circuits have failed recently
so the new one didn't launch. we need to tolerate that.
svn:r2438
files have really old descriptors for the authdirservers, so we're
asking them in the new format because they're too old.
now we actually compare the version to a cutoff version, and act
appropriately.
also take this chance to use only >=0.0.8 servers for dns resolves,
because of the recent bugs. we'll bump to >=0.0.9pre1 once there are
some servers running that.
svn:r2380
bugfix: we were retrying the same circuit after getting a resolve
failure. so of course the next two tries would fail too. now we try
a new circuit each time (at most three times).
svn:r1867
* \file circuitbuild.c
* \brief The actual details of building circuits.
* \file circuitlist.c
* \brief Manage the global circuit list.
* \file circuituse.c
* \brief Launch the right sort of circuits, attach streams to them.
* \file connection_edge.c
* \brief Handle edge streams.
* \file onion.c
* \brief Functions to queue create cells, and handle onionskin
* parsing and creation.
* \file relay.c
* \brief Handle relay cell encryption/decryption, plus packaging and
* receiving from circuits.
svn:r1863
