Network-Programming-in-C/Conversion_Functions/readme.md

Functions' used are :-

Functions for conversion between network and host byte order :

1. uint32_t htonl( uint32_t hostlong )

   • Convert hostlong in host byte order to network byte order.

2. uint16_t htons( uint16_t hostshort )

   • Convert hostshort in host byte order to network byte order.

3. uint32_t ntohl( uint32_t netlong )

   • Convert netlong in network byte order to host byte order.

4. uint16_t ntohs( uint16_t netshort )

   • Convert netshort in network byte order to host byte order.

Functions for conversion between network representation to presentation representation :

Since the IP address are presentable in form of (for eg.) 194.10.11.5 for IPv4, but the actual representation in network is in raw byte form. So, for easy conversion between the two, apis are provided for such conversion.

1. const char *inet_ntop(int af, const void* src, char* dst, socklen_t size)

   Parameters :

   • af :

     Type : int

     Value : AF_INET, AF_INET6.

     Purpose : Used to specify type of address we are converting (IPv4 or IPv6).

   • src :

     Type : const void *

     Value : Buffer containing raw byte address in form.

   • dst :

     Type : char *

     Value : Buffer for storing the IP address in presentable form.

   • size :

     Type : socklen_t

     Value : INET_ADDRSTRLEN or INET6_ADDRSTRLEN.

     Purpose : Maximum size of buffer to store the IP address.

   Return type :

   • Type : const char *

   • Purpose : Pointer to dst if no error occured, otherwise returns null pointer and set global error variable errno.

2. int inet_pton(int af, const char *src, void *dst)

   Parameter :

   • af :

     Type : int

     Value : AF_INET, AF_INET6.

     Purpose : Used to specify type of address we are converting (IPv4 or IPv6).

   • src :

     Type : const char *

     Value : String to convert address in presentable form to network compatible form.

   • dst :

     Type : void *

     Value : empty buffer.

     Purpose : To store address in network compatible form.