1On Mac OS X, mDNSResponder now runs with user-ID and group-ID
2"_mdnsresponder". In order to perform certain privileged operations, a
3helper (unimagintively called mDNSResponderHelper) runs as root when
4needed and handles requests from mDNSResponder.
5
6
7* A new LaunchD job com.apple.mDNSResponderHelper starts
8  mDNSResponderHelper on demand.  The helper exits after approximately
9  10 seconds of idle time.
10
11* The com.apple.mDNSResponder LaunchD job specifies the account under
12  which to run, so that mDNSResponder starts as _mdnsresponder.
13
14* A subdirectory named "mdns" and owned by _mdnsresponder has been
15  created in /var/run.  The PID file and uDNS server socket has been
16  moved to that subdirectory.
17
18* There are currently six remote procedure calls handled by
19  mDNSResponderHelper: mDNSPreferencesSetName, mDNSKeychainGetSecrets,
20  mDNSConfigureServer, and mDNSAutoTunnelSetKeys
21
22* mDNSPreferencesSetName allows mDNSResponder to set the computer name
23  or local host name, and displays a notification if there was a
24  conflict.
25
26* mDNSKeychainGetSecrets causes mDNSResponderHelper to collect DNS
27  keys from the system keychain.  SetDomainSecrets uses the result to
28  populate AuthInfoList.  One could refactor this code further so that
29  mDNSResponderHelper performs all the cryptographic operations, with
30  the result that a compromise of mDNSResponder does not compromise
31  keys.  But I think that may be more change than is advisable at this
32  point.
33
34* On the advice of the Security.framework team, I've used
35  SecKeychainSetPreferenceDomain to ensure that the system keychain is
36  references whenever a NULL SecKeychainRef is used.  Wherever a
37  SecKeychainRef is needed, NULL is now specified.
38
39* mDNSConfigureServer, and mDNSAutoTunnelSetKeys do various setup and
40  teardown for BTMM.
41