In our privsep model, imsg is often used to transport sensitive
information between processes. But a process might free an imsg, and
reuse the memory for a different thing. iked uses some
explicit_bzero() to clean imsg-buffer but doing it in the library with
the freezero() is less error-prone and also benefits other daemons.
OK deraadt@ jsing@ claudio@
the standard realloc*() functions can leave behind. imsg buffers are
sometimes used in protocol stacks which require some secrecy, and layering
violations would be needed to resolve this issue otherwise.
Discussed with many.
EAGAIN causes spinning.
fix from claudio:
"Let msgbuf_write return -1 with errno EAGAIN. The users then must
check if this was the case and readd the event or poll again. The
current handling in the imsg code is wrong for sure."
ok gilles
on descriptors, this can be achieved thanks to the new getdtablecount()
system call. application may provide a reserve count to ensure that the
recvmsg() call is not called when they don't have enough descriptors to
work properly.
change the API so that transient errors that can be retried immediately
are retried within the function right away, whereas transient errors for
which the application may want to take action will set errno to EAGAIN.
ok deraadt@ and henning@
function, which is additionally exported for use by others.
It will be needed by smtpd's SSL module when the SMTP client code
is changed to replace libevent's evbuffers with our msgbuf_* API.
ok gilles@ henning@ guenther@ eric@
it is just capable of answering (s)ntp4 requests with the local time
for now.
imsg/buffer and logging framework from bgpd, ntp protocol hackery
with Alexander Guy
bcook