| On Mac OS X, mDNSResponder now runs with user-ID and group-ID |
| "_mdnsresponder". In order to perform certain privileged operations, a |
| helper (unimagintively called mDNSResponderHelper) runs as root when |
| needed and handles requests from mDNSResponder. |
| |
| |
| * A new LaunchD job com.apple.mDNSResponderHelper starts |
| mDNSResponderHelper on demand. The helper exits after approximately |
| 10 seconds of idle time. |
| |
| * The com.apple.mDNSResponder LaunchD job specifies the account under |
| which to run, so that mDNSResponder starts as _mdnsresponder. When |
| run as root--- e.g. from the command line with `sudo'--- |
| mDNSResponder drops privileges itself. |
| |
| * A subdirectory named "mdns" and owned by _mdnsresponder has been |
| created in /var/run. The PID file and uDNS server socket has been |
| moved to that subdirectory. |
| |
| * There are currently six remote procedure calls handled by |
| mDNSResponderHelper: mDNSDynamicStoreSetConfig, |
| mDNSPreferencesSetName, mDNSKeychainGetSecrets, |
| mDNSConfigureServer, and mDNSAutoTunnelSetKeys |
| |
| * mDNSDynamicStoreSetConfig allows mDNSResponder to set the |
| MulticastDNS, PrivateDNS, or DynamicDNS configurations. |
| |
| * mDNSPreferencesSetName allows mDNSResponder to set the computer name |
| or local host name, and displays a notification if there was a |
| conflict. |
| |
| * mDNSKeychainGetSecrets causes mDNSResponderHelper to collect DNS |
| keys from the system keychain. SetDomainSecrets uses the result to |
| populate AuthInfoList. One could refactor this code further so that |
| mDNSResponderHelper performs all the cryptographic operations, with |
| the result that a compromise of mDNSResponder does not compromise |
| keys. But I think that may be more change than is advisable at this |
| point. |
| |
| * On the advice of the Security.framework team, I've used |
| SecKeychainSetPreferenceDomain to ensure that the system keychain is |
| references whenever a NULL SecKeychainRef is used. Wherever a |
| SecKeychainRef is needed, NULL is now specified. |
| |
| * mDNSConfigureServer, and mDNSAutoTunnelSetKeys do various setup and |
| teardown for BTMM. |
