Even during execution of a request it is possible that there will be
no session available, notably in case of renegotiation.  As a result
logging of $ssl_session_id in some cases caused NULL pointer dereference
after revision 97e3769637a7 (1.5.9).  The check added returns an empty
string if there is no session available.

Previously, it used to contain full session serialized instead of just
a session id, making it almost impossible to use the variable in a safe
way.

Thanks to Ivan Ristić.

If c->read->ready was reset, but later some data were read from a socket
buffer due to a call to ngx_ssl_recv(), the c->read->ready flag should
be restored if not all data were read from OpenSSL buffers (as kernel
won't notify us about the data anymore).

More details are available here:
http://mailman.nginx.org/pipermail/nginx/2013-November/041178.html

Use of accept mutex on win32 may result in a deadlock if there are multiple
worker_processes configured and the mutex is grabbed by a process which
can't accept connections.

Due to a bad argument list, nginx worker would crash (SIGSEGV) while
trying to log the fact that it received OCSP response with "revoked"
or "unknown" certificate status.

While there, fix similar (but non-crashing) error a few lines above.

Signed-off-by: Piotr Sikora <piotr@cloudflare.com>

Evenport method needs more work.  Changes in r5172, while being correct,
introduce various new regressions with current code.

We generate both read and write events if an error event was returned by
port_getn() without POLLIN/POLLOUT, but we should not try to handle inactive
events, they may even have no handler.

Stale write event may happen if read and write events was reported both,
and processing of the read event closed descriptor.

In practice this might result in "sendfilev() failed (134: ..." or
"writev() failed (134: ..." errors when switching to next upstream server.

See report here:
http://mailman.nginx.org/pipermail/nginx/2013-April/038421.html

Problems with setsockopt(TCP_NODELAY) and setsockopt(TCP_NOPUSH), as well
as sendfile() syscall on Solaris, are specific to UNIX-domain sockets.
Other address families, i.e. AF_INET and AF_INET6, are fine.