DNSResolver

ClearAddressCache GetHostByAddress GetHostByName HandlePDU RegisterDNS ResetClass UnregisterAllDNS UnregisterDNS

Attributes

Class DNSResolver defines no new attributes.

Fields

instance DNSResolver tag;
         server: nilObject;
        dnsList: nilObject;
          dnrID: 0;
          cache: nilObject;
lastClearedDate: 0;
end instance;

Define Class DNSResolver;
    inherits from Object;
    inherits from PDUClientInterface;

    field server: PDUServer;
    field dnsList: IntegerList;             
        // list of domain name servers to query
    field dnrID: UnsignedShort;             
        // next id
    field cache: ObjectList;                
        // list of cache nodes, newest last
    field lastClearedDate: Signed;          
        // last day the cache was cleared

    overrides ResetClass;
        // unregisters all DNS entries and clears the cache
    overrides HandlePDU;

    // DNS lookups.  GetHostByName & GetHostByAddress throw an iDNSLookupFailed
    // exception when a DNS lookup fails, or iNoDNSRegistered if no DNS
    // was registered to provide lookups
    
    operation GetHostByName(hostName: Text): Unsigned;
        // returns the IP address for a 'hostName' of the form "host.acme.net"
        // by doing a DNS lookup.
    operation GetHostByAddress(ipAddress: Unsigned): Text;
        // returns the host name for 'ipAddress' by doing a DNS lookup.  
        
    operation RegisterDNS(ipAddress: Unsigned);
        // adds the DNS to the end of the list of DNSes to query
    operation UnregisterDNS(ipAddress: Unsigned);
        // removes the DNS from the list of DNSes to query

    operation UnregisterAllDNS();
        // clears out the list of registered DNSes
    operation ClearAddressCache();
        // removes all entries cached from DNS lookups
end class;