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copied!<p>Here's an example program written in C (since I don't know C++). It's fairly fast, but I'm not really happy with it. Maybe someone can help me improve it.</p> <p><strong>Edit:</strong> Obviously, I wrote this before it was turned into a PHP-only question. Turning this into PHP is left as an exercise to the reader (ew).</p> <pre class="lang-c prettyprint-override"><code>#include <arpa/inet.h> #include <string.h> #include <stdlib.h> #include <errno.h> #include <stdio.h> #include <ctype.h> /* * Syntax: ./ipv6_list <ip>/<cidr-prefix> */ int main(int argc, char **argv) { uint8_t start[16]; uint8_t address[16]; uint8_t mask[16] = { 0 }; uint8_t prefix = 128; char *prefix_location; int i; /* This is the octet that, when changed, will result in <IP> & <mask> != <start IP> */ int mask_check_octet = 0; if(argc != 2) return 1; /* Find prefix */ if((prefix_location = strstr(argv[1], "/")) != NULL) { char *prefix_search = prefix_location + 1; char *prefix_remaining; long prefix_test; if(!isdigit(*prefix_search)) return 2; errno = 0; prefix_test = strtol(prefix_search, &prefix_remaining, 10); if(errno == ERANGE || prefix_test < 0 || prefix_test > 128 || strcmp(prefix_remaining, "") != 0) return 2; prefix = (uint8_t)prefix_test; *prefix_location = '\0'; /* So we can just pass argv[1] into inet_pton(3) */ } /* Convert prefix into mask */ for(i = 0; i < 16; i++) { if(prefix == 0) break; mask_check_octet = i; if(prefix < 8) { mask[i] = ~((1 << (8 - prefix)) - 1); break; } else mask[i] = UINT8_MAX; prefix -= 8; } /* Find address */ if(inet_pton(AF_INET6, argv[1], start) != 1) return 3; /* Start at the beginning of the network */ for(i = 0; i < 16; i++) { start[i] &= mask[i]; address[i] = start[i]; } /* Iterate */ while((address[mask_check_octet] & mask[mask_check_octet]) == start[mask_check_octet]) { char address_str[INET6_ADDRSTRLEN]; inet_ntop(AF_INET6, address, address_str, sizeof(address_str)); printf("%s\n", address_str); /* Add one to the address */ for(i = 15; i >= 0; i--) { if(address[i] != UINT8_MAX) break; } address[i]++; for(i++; i < 16; i++) address[i] = 0; }; return 0; } </code></pre> <p>You can use standard shell commands to limit its output (or just modify the <code>while</code> loop):</p> <pre class="lang-none prettyprint-override"><code>nfontes@brioche:~$ ./ipv6_list '2607:fc50:0:d00::0/106' | head -n 200 2607:fc50:0:d00:: 2607:fc50:0:d00::1 2607:fc50:0:d00::2 2607:fc50:0:d00::3 2607:fc50:0:d00::4 2607:fc50:0:d00::5 2607:fc50:0:d00::6 2607:fc50:0:d00::7 2607:fc50:0:d00::8 2607:fc50:0:d00::9 2607:fc50:0:d00::a 2607:fc50:0:d00::b 2607:fc50:0:d00::c 2607:fc50:0:d00::d 2607:fc50:0:d00::e [...] 2607:fc50:0:d00::c0 2607:fc50:0:d00::c1 2607:fc50:0:d00::c2 2607:fc50:0:d00::c3 2607:fc50:0:d00::c4 2607:fc50:0:d00::c5 2607:fc50:0:d00::c6 2607:fc50:0:d00::c7 </code></pre>

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