properly distribute the certificates between the SSL context's trust
store and our host cert list.
as a drive-by, clean up some nasty type casts at the cost of including
a second OpenSSL header into socket.h.
... by making a lot of objects unsigned, and some signed.
casts which lose precision and change the sign in one go (ssize_t and
time_t to uint on LP64) are made explicit as well.
this is actually potentially counterproductive, as people who have set
SSLVersions and fail to adjust it will _lose_ tls 1.3 support. however,
without the option being there, people (incorrectly) believe that tls
1.3 is not supported.
Some distributions (e.g. Fedora) added support for system wide crypto
policies. This is supported in most common crypto libraries including
OpenSSL. Applications can override this policy using their own cipher
string. This commit adds support for specifying the cipher string in
the mbsync configuration.
For example, to exclude Diffie-Hellman, the user can specify
CipherString "DEFAULT:!DH"
in the IMAP Account's configuration.
we need to deep-copy the struct hostent data, as otherwise the
concurrent connects will overwrite each other's lookup results.
this is a rather hypothetical fix, as the bug currently affects only
channels connecting two IMAP accounts, and only if the first host's
first address asynchronously fails to connect.
our current project structure precludes the clash between some indirect
include of ssl.h and our definition of 'S' (or 'M', i don't remember)
that happened on some system, so there is no need to avoid including it
any more.
this avoids complaints from some more picky compilers, as re-defining
typedefs (even to the same thing) is illegal before C11.
any structures may be invalid after callback invocation.
this has the side effect that the socket write callback now returns
void, like all other callbacks do.
the synchronous writing to the socket would have typically invoked the
write callback, which would flush further commands, thus recursing.
we take the easy way out and make it fully asynchronous, i.e., no data
is sent before (re-)entering the event loop.
this also has the effect that socket_write() cannot fail any more, and
any errors will be reported asynchronously. this is consistent with
socket_read(), and produces cleaner code.
this introduces a marginal performance regression: the maildir driver is
synchronous, so all messages (which fit into memory) will be read before
any data is sent. this is not considered relevant.
propagating many messages from a fast store (typically maildir or a
local IMAP server) to a slow asynchronous store could cause gigabytes of
data being buffered. avoid this by throttling fetches if the target
context reports memory usage above a configurable limit.
REFMAIL: 9737edb14457c71af4ed156c1be0ae59@mpcjanssen.nl
the primary objective is reducing the number of small SSL packets (which
are always padded), but fewer syscalls in the non-SSL case should be
good as well.
instead of keeping the structures in an opaque array (which was a shadow
of the struct pollfd array if poll() was supported), make them directly
addressable.
this has the advantage that notifier-altering operations (mostly
en-/disabling) don't need to look up the structure by file handle each
time.
on the downside, data locality in the main loop is worse.
neither of these have any real effect on performance.
note that the structures are not allocated separately, but embedded into
the the parent structure (like sockets already were).
we should make no assumptions about the layout of OpenSSL's certificate
store, in particular when they are wrong. so copy the interesting part
instead of "deep-linking" into it.
this code is uglier than it should be, but OpenSSL's extensive use of
macros to manage data types would force us to include the ssl headers
into our headers otherwise, which would be even uglier.
REFMAIL: <545442CC.9020400@nodivisions.com>
instead of using a callback which messes with the certificate chain
verification, simply let OpenSSL ignore errors during that phase and
check the result only afterwards.
the combinations of the various options made quite a mess. additionally,
'RequireSSL no' is inherently insecure - "use SSL if available" is plain
stupid.
the old options are still accepted, but will elicit a warning.
it doesn't belong there - it's a property of imap_server_conf_t.
the port setup is now done while reading the config.
this makes socket.[hc] imap-agnostic.
