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Intro to "Support Functions" for Network Programming

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• Network Support Functions
  • Fact:

    Computer on the Internet are identified by their IP addresses When we wish to visit google.com, we need to use its IP address !!!           (Analogy: dial the telephone number) IP-addresses are binary numbers It is tedious to remember a binary number !!!

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  • Functions to support network programming:

    Lookup function to find the corresponding IP address of a symbolic host name Example: You are given the symbolic host name, e.g.: www.google.com Find the IP address for www.google.com          Analogy: look up in a telephone directory Reverse look up function: You are given an IP address Find the symbolic host name for that IP address Dotted decimal address to binary IP address translation: You are given a dotted decimal IP address, e.g.: "170.140.150.1" Find the corresponding binary IP address

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• The network service library

  • The network service library for C:

    network service library (nsl) = a function library in C programming language that contains the IP address conversion functions

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  • Compiling programs that uses the network service library functions:

    When your network program uses some network service function(s): You need to link the network service library (nsl) when you compile your program

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  • How to link the network service library:

    cc -o my-netw-prog my-netw-prog.c -lnsl