auth: Code cleanup - avoid using void *context auth_request_callback_t always uses struct auth_client/master_connection* in the context - no need to try to be too generic here.

auth: Code cleanup: Avoid using auth_stream_reply as temporary strings.

Added support to perform token-based service process authentication. Creates hidden SASL method DOVECOT-TOKEN. This method is not available on the normal auth login socket and thus never presented to clients. Creates new auth socket type 'tokenlogin'. This otherwise normal login socket only offers authentication using the DOVECOT-TOKEN mechanism. Creates new token-login directory in base_dir to separate token logins from normal logins. This directory is otherwise completely identical to the normal login dir, i.e. it contains sockets for the service backends, used to chroot login processes to, etc. Makes default login socket configurable. Performs some minor changes to src/login-common to build very sparse protocols, e.g. avoid the need to implement methods that are not needed.

Removed CONTEXT_TYPE_SAFETY macro and reimplemented its functionality better. gcc/clang now gives a compiler error in many places if callback isn't exactly what was expected. It's also now much easier to add more of these checks.

auth: Log a warning if auth client disconnects while it still has pending requests.

auth: Don't assert-crash if a request still succeeds after its client connection is gone.

auth: Changed how auth deinitilization works. --HG-- branch : HEAD

auth: Removed unnecessary auth_request callback and context uses. --HG-- branch : HEAD

auth: Fixes to destroying pending async userdb requests at deinit. --HG-- branch : HEAD

auth: Aborting pending async requests on deinit caused crashes. --HG-- branch : HEAD

login: Tell auth process to free aborted auth requests. --HG-- branch : HEAD

auth: Separate auth and login connections. Non-login requests are freed immediately after auth finished. The login connections are used by Dovecot internally, while the auth connections are for SMTP AUTH etc. --HG-- branch : HEAD

auth: Initial support for per-protocol auth settings. Currently the list of services is hard-coded. This should be changed so that config lookup returns the service names. --HG-- branch : HEAD

auth: Auth request handler no longer keeps struct auth pointer. --HG-- branch : HEAD

auth: Don't loop through active requests every 5 seconds, looking for timeouts. --HG-- branch : HEAD

Use auth-stream API to build all TAB-delimited strings to make sure strings are escaped properly where necessary. --HG-- branch : HEAD

Make sure failed auth requests stay in failure buffer for at least a second. --HG-- branch : HEAD

Changed .h ifdef/defines to use <NAME>_H format. --HG-- branch : HEAD

Type safe callbacks weren't as easy as I thought. Only callback(void *context) can be handled generically. Others can be handled specially, but only if all the parameters are pointers, otherwise eg. int parameter can be replaced with long without compiler giving any warnings. --HG-- branch : HEAD

Added context parameter type safety checks for most callback APIs. --HG-- branch : HEAD

deinit, unref, destroy, close, free, etc. functions now take a pointer to their data pointer, and set it to NULL. This makes double-frees less likely to cause security holes. --HG-- branch : HEAD

Added "bool" type and changed all ints that were used as booleans to bool. --HG-- branch : HEAD

Removed unused code --HG-- branch : HEAD

Allow multiple master connections for a single listener. --HG-- branch : HEAD

Restructuring of auth code. Balancer auth processes were a bad idea. Usually the balancer itself took as much CPU as the actual workers because it acted as a proxy. Now auth worker means different thing: they're used to execute blocking passdb and userdb queries. Currently just MySQL (PAM and checkpassword in TODO). --HG-- branch : HEAD

Changed the way multiple auth processes are handled. It no longer uses a pid appended to socket name but instead there's a balancer process which proxies the requests to worker processes. --HG-- branch : HEAD

Moving code around. --HG-- branch : HEAD