Iterate range of addresses between two IPV6 addresses

Question

I need some way to iterate over the range of addresses between two IPv6 addresses. i.e. if the first IP is 2a03:6300:1:103:219:5bff:fe31:13e1 and the second one is 2a03:6300:1:103:219:5bff:fe31:13f4, I would like to visit the 19 addresses in that range.

With IPv4 I just do inet_aton for string representation and get htonl of s_addr in the resulting struct, but how can I do that for IPv6?

For simplify:

struct in6_addr sn,en;
long i;

s="2a03:6300:1:103:219:5bff:fe31:13e1";
e="2a03:6300:1:103:219:5bff:fe31:13f4";

inet_pton(AF_INET6,s,&sn);
inet_pton(AF_INET6,e,&en);

[..]

for (i = _first_ipv6_representation; i<=_second_ipv6_representation; i++){
    /* stuck here */
}

Answer 1

Old answer stricken per your comments, updated to iterate a range of addresses:

char output[64];
struct in6_addr sn, en;
int octet;

s="2a03:6300:1:103:219:5bff:fe31:13e1";
e="2a03:6300:1:103:219:5bff:fe31:13f4";

inet_pton(AF_INET6,s,&sn);
inet_pton(AF_INET6,e,&en);

for ( ; ; ) {
    /* print the address */
    if (!inet_ntop(AF_INET6, &sn, output, sizeof(output))) {
        perror("inet_ntop");
        break;
    }

    printf("%s\n", output);

    /* break if we hit the last address or (sn > en) */
    if (memcmp(sn.s6_addr, en.s6_addr, 16) >= 0) break;

    /* increment sn, and move towards en */
    for (octet = 15; octet >= 0; --octet) {
        if (sn.s6_addr[octet] < 255) {
            sn.s6_addr[octet]++;
            break;
        } else sn.s6_addr[octet] = 0;
    }

    if (octet < 0) break; /* top of logical address range */
}