expand an IPv6 address so I can print it to stdout

Question

I am using getifaddrs() and inet_ntop() to get the ip addresses on the system. When the system is set to IPv6 the address returned is in the shortened version (using :: for

Answer 1

void ipv6_to_str_unexpanded(char * str, const struct in6_addr * addr) {
   sprintf(str, "%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                 (int)addr->s6_addr[0], (int)addr->s6_addr[1],
                 (int)addr->s6_addr[2], (int)addr->s6_addr[3],
                 (int)addr->s6_addr[4], (int)addr->s6_addr[5],
                 (int)addr->s6_addr[6], (int)addr->s6_addr[7],
                 (int)addr->s6_addr[8], (int)addr->s6_addr[9],
                 (int)addr->s6_addr[10], (int)addr->s6_addr[11],
                 (int)addr->s6_addr[12], (int)addr->s6_addr[13],
                 (int)addr->s6_addr[14], (int)addr->s6_addr[15]);
}

Answer 2

            #include<stdio.h>
            #include <netinet/in.h>
            #include <arpa/inet.h>

            struct in6_addrr
            {
                unsigned char addr[16];
            };

            void ipv6_expander(const struct in6_addr * addr)
            {
                char str[40];
                sprintf(str,"%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
                (int)addr->s6_addr[0], (int)addr->s6_addr[1],
                (int)addr->s6_addr[2], (int)addr->s6_addr[3],
                (int)addr->s6_addr[4], (int)addr->s6_addr[5],
                (int)addr->s6_addr[6], (int)addr->s6_addr[7],
                (int)addr->s6_addr[8], (int)addr->s6_addr[9],
                (int)addr->s6_addr[10], (int)addr->s6_addr[11],
                (int)addr->s6_addr[12], (int)addr->s6_addr[13],
                (int)addr->s6_addr[14], (int)addr->s6_addr[15]);
                 printf("\nExpanded ipv6 Addr %s\n",str);
            }

            int main(int argc,char *argv[])
            {
                struct in6_addrr ipv6;
                printf("\nGiven IPv6 Addr %s\n",argv[1]);
                if(inet_pton(AF_INET6,argv[1],&ipv6.addr))
                {
                    ipv6_expander(&ipv6.addr);
                }
                else
                {
                    printf("\n error\n");
                }
                return;
            }