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15.  Address Class

Object Modeling Technique (OMT) view of the SNMP++ Address Class

 

15.1.  What is the Network Address Class?

The network address class is a set of C++ classes which provide for simple, safe, portable  and efficient use of network addresses. Most network management applications require use of network addresses for accessing and managing devices. This includes address validation, modification and user interface control. Rather than manage all the internal details of particular network addresses, the Address class encapsulates and hides the internal mechanisms freeing the application programmer to focus on the problem at hand. The motivation for the development of the Address class emerged from input and discussion at the ‘95 Interop SNMP++ Birds-of-A-Feather (BOF) and from dialog with Hewlett-Packard OpenView programmers. 

15.2. Why use the Network Address Class?

The address class provides a number of benefits including: automatic memory management, address validation, portability to any C++ environment, ease of use and extensibility. Currently, the Address class consists of four classes, the IpAddress Class, the IpxAddress Class, the MacAddress class and the GenAddress class. In the future other subclasses will be added including IP Next Generation (IPng).  

15.3. Address Classes

The address classes are based around one abstract class, the Address class. This is an abstract class. That is, there may be no instances of this class. The Address class provides a consistent interface through the use of virtual member functions. This allows passing addresses to other functions using the generic interface. This minimizes code changes to modules using addresses. 

 

15.4. Address Classes and Interfaces

The base class, the Address class is an abstract class. The class contains the commonality of all derived address classes. This includes an identical interface for constructing, accessing and mutating Addresses.

Address Class Member Functions

Description

IpAddress Class Constructors

 

      IpAddress::IpAddress( void);

Construct an empty IpAddress object.

      IpAddress::IpAddress( const char *string);

Construct an IpAddress from a string, do DNS if needed.

      IpAddress::IpAddress( const IpAddress &ipa);

Copy constructor.

IPAddress Member Functions

 

      char * friendly_name( int & status);

Invokes DNS lookup for friendly name.

UdpAddress Constructors

 

     UdpAddress::UdpAddress( void);

Construct an invalid UdpAddress Object.

     UdpAddress::UdpAddress( const char *string);

Construct a UdpAddress using a char string.

     UdpAddress::UdpAddress( const UdpAddress &udpa);

Construct a UdpAddress using another UdpAddress.

UdpAddress Member Functions

 

     void UdpAddress:set_port( const unsigned int p);

Set the port number for a UdpAddress object.

     unsigned int UdpAddress::get_port();

Get the port number from a UdpAddress object.

IpxAddress Class Constructors

 

      IpxAddress::IpxAddress( void);

Construct an empty IPX address.

      IpxAddress::IpxAddress( const char *string);

Construct an IPX address using a char string.

      IpxAddress::IpxAddress( const IpxAddress &ipxa);

Copy constructor.

IpxSockAddress Constuctors

 

     IpxSockAddress::IpxSockAddress( void);

Construct an empty IpxSockAddress object.

     IpxSockAddress::IpxSockAddress( const char *string);

Construct a IpxSockAddress using a char string.

     IpxSockAddress::IpxSockAddress( const IpxSockAddress   &ipxs);                                                  

Construct a IpxSockAddress using another IpxSockAddress.

IpxSockAddress Member Functions

 

     IpxSockAddress::set_socket( const unsigned int s);

Get the socket number from a IpxSockAddress.

     unsigned int IpxSocketAddress::get_socket();

Set the socket number into a IpxSockAddress.

MacAddress Constructors

 

      MacAddress::MacAddress( void);

Construct an empty MacAddress object.

      MacAddress::MacAddress( const char * string);   

Construct a MacAddress from a string.

      MacAddress::MacAddress( const MacAddress &mac);

Copy constructor.

GenAddress Constructors

 

     GenAddress::GenAddress( void);

Construct a invalid GenAddress object.

     GenAddress::GenAddress( const char * addr);

Construct a GenAddress using a string.

     GenAddress::GenAddress( const GenAddress &addr);

Copy constructor.

Common Member Functions, applicable to all Address classes

 

      int operator == ( const Address &lhs, const Address rhs);

Determine if two Addresses are equal.

      int operator != ( const Address &lhs, const Address &rhs);

Determine if two Addresses are not equal.

      int operator > ( const Address &lhs, const Address &rhs);

Determine if one Address is greater than another.

      int operator >= (const Address &lhs, const Address &rhs);

Determine if one Address is greater than or equal.

      int operator < ( const Address &lhs, const Address &rhs);

Determine if one Address is less than another.

      int operator<=( const Address &lhs, const Address &rhs);

Determine if one Address is less than or equal to another.

      int operator == ( const Address &lhs, cosnt char *inaddr);

Determine if two Addresses are equal.

      int operator > ( const Address &lhs, const char *inaddr);

Determine if an Address if greater than a string.

      int operator < ( const Address &lhs, const char *inaddr);

Determine if an Address is less than a string.

      virtual int valid( );        

Determine if an Address is valid.

      unsigned char& operator[]( int position);

Allow access to an Address object using array like access.

      char * get_printable ( );

Returns Address formatted for output.

 

15.5. IpAddress Class Special Features

The IpAddress class will do automatic Domain Name Services (DNS) lookup when calling the Address::get_printable() member function. If the DNS is not active or if the address cannot be resolved, the dotted format will be returned. Alternatively, an IpAddress can be constructed with a friendly name. In this case the constructor will invoke the DNS lookup. If the friendly name cannot be found, the address is invalid. This powerful feature allows you to utilize friendly names in your IpAddress user presentation.

15.6. GenAddress

The GenAddress class allows creation and usage of generic addresses where a GenAddress may take on the behavior and attributes of any of the other Address classes ( IpAddress, IpxAddress and MacAddress). When working with arbitrary addresses, you may use a GenAddress. The constructor for the GenAddress class allows creating an Address with any character string. The constructor determines the specific type of Address which matches the string and thereafter gives the GenAddress the attributes and behavior of that Address. This saves the programmer from having to write code which explicitly deals with the differences across Addresses.

GenAddress Examples