Use a callback-based API for DNS lookup, in preparation for ADNS

integration.  Block clients, and make them invisible for all other
clients, until the DNS lookup has completed.

The session_start field of a Connection was used both to record the
connect time and the login/logout time.  As a result, the
connection-time of a Static-Session-Info was not actually static.
Fixed by keeping track of the connect time and the login/logout
separately.

ChangeLog

+2003-08-05  Per Cederqvist  <ceder@ceder.dyndns.org>
+
+	Use a callback-based API for DNS lookup, in preparation for ADNS
+	integration.  Block clients, and make them invisible for all other
+	clients, until the DNS lookup has completed.
+	* doc/lyskomd.texi (Files): Document the handshake_ok field of
+	connections.txt.
+	(Function Templates for send-async.c): Include a call to
+	handshake_ok() in prototype code.
+	(Traversing Connections): Ditto.
+	* src/server/session.c:  All users of the hostname updated to get
+	it from the isc_scb.
+	(who_is_on): Removed dead code.
+	(who_is_on_ident): Ditto.
+	(who_is_on_dynamic): Removed dead code.  Don't include sessions
+	until the handshake is completed.
+	(get_session_info): Don't include sessions until the handshake is
+	completed.
+	(get_static_session_info): Don't include sessions until the
+	handshake is completed.  
+	(get_session_info_ident): Ditto.
+	(disconnect): Don't include sessions until the handshake is
+	completed.
+	(get_client_name): Ditto.
+	(get_client_version): Ditto.
+	* src/server/send-async.c (async_new_text_old): Use handshake_ok()
+	to check if it is OK to send the message to the client.  As a
+	result, the message will not be sent until the DNS lookup has
+	completed.
+	(async_new_text): Ditto.
+	(async_i_am_on): Ditto.
+	(async_logout): Ditto.
+	(async_new_name): Ditto.
+	(async_forced_leave_conf): Ditto.
+	(async_login): Ditto.
+	(async_deleted_text): Ditto.
+	(async_new_recipient): Ditto.
+	(async_sub_recipient): Ditto.
+	(async_new_membership): Ditto.
+	(async_new_user_area): Ditto.
+	(async_garb_ended): Ditto.
+	(async_sync_db): Ditto, but ignore the DNS lookup.
+	(async_rejected_connection): Ditto.
+	* src/server/prot-a.c (prot_a_parse_packet): Disable the session
+	after the initial handshake if the dns resolution hasn't completed
+	yet.
+	* src/server/membership.c (send_async_new_membership): Indentation
+	fixed.
+	* src/server/internal-connections.h (enum ignored_conditions): New
+	enum.
+	(handshake_ok): New function.
+	* src/server/internal-connections.c (init_connection): Updated to
+	initialize all fields.  Several were forgotten.
+	(kill_client): Clear the remote_ip.
+	(handshake_ok): New function.
+	* src/server/connections.h (Connection): Removed the hostname
+	field, since that is now stored as isc_session->remote.  Added
+	dns_done, blocked_by_dns, and remote_ip.
+	* src/server/connections.c (dump_connections): Include a flag that
+	tells if the session has completed the handshake or not.
+	(dns_resolution): New function.
+	(get_host_name): Removed.
+	(login_request): Reorganized the code to use the new
+	callback-driven API of ISC host lookups.
+	* src/server/admin.c (shutdown_kom): Get the host name from the
+	isc_scb, now that the information is no longer stored in the
+	connection.
+	* src/libraries/libmisc/timeval-util.h,
+	src/libraries/libmisc/timeval-util.c (timeval_diff_d): New
+	function.
+
+	The session_start field of a Connection was used both to record
+	the connect time and the login/logout time.  As a result, the
+	connection-time of a Static-Session-Info was not actually static.
+	Fixed by keeping track of the connect time and the login/logout
+	separately.
+	* src/server/connections.h (Connection): Replaced the
+	session_start field with connect_time and login_time.  All users
+	updated.  
+	* src/server/session.c: (login_old): Set login_time, not connect_time.
+	(login): Ditto.
+	(logout): Use login_time, not connect_time.
+	(get_session_info): Use connect_time, not login_time, as the
+	connection_time.
+	(get_static_session_info): Use connect_time, not login_time, as the
+	connection_time.
+	(get_session_info_ident): Ditto.
+	* src/server/internal-connections.c (new_client): Set both
+	connect_time and login_time.
+	* src/server/connections.c (handle_accept_event): Call set_time(),
+	so that the connect_time is set correctly.
+
 2003-08-04  Per Cederqvist  <ceder@ceder.dyndns.org>
 
 	Don't leave whitespace in the input buffers.