Chapter 11.4, Problem 11.4PP

Program Plan Intro

IP addresses:

• The IP address denotes an unsigned integer that is 32-bit.
• The IP addresses is been stored by network programs in IP address structure.
• The addresses present in IP address structure are stored in network byte order.
•  An unsigned 32-bit integer is converted from host byte order to network byte order by “htonl” function.
• An unsigned 32-bit integer is converted from network byte order host byte order by “ntohl” function.
• The IP address is presented to humans in a form known as “dotted-decimal” notation.
  • Each byte is been represented by its corresponding decimal value and is separated by a period from other bytes.

The getaddrinfo Function:

• It converts string representation of hostnames, host addresses, service names and port numbers into structures of socket address.
• It denotes replacement for “gethostbyname” and “getservbyname” functions.
• The two components of socket address denote “host” and “service”, the method returns result that points to a linked list of “addrinfo” structures.
• The “host” argument can either be a domain name or a numeric address.
• The “service” argument can be either a service name or a decimal port number.

The getnameinfo Function:

• It converts structures of socket address to corresponding host and service name strings.
• It denotes replacement for “gethostbyaddr” and “getservbyport” functions.
• The argument “sa” points to a structure of socket address with size “salen” bytes.
• It points to host with buffer of size “hostlen” bytes and “service” to a buffer of size “servlen” bytes.
• The result is been copied into “host” and “service” buffers.
• If it returns a non-zero error code, the application can convert it to a string by calling “gai_strerror”.