1 files changed, 63 insertions, 0 deletions
diff --git a/src/tools/ipv4-range-expander/ipv4-range-expander.service.ts b/src/tools/ipv4-range-expander/ipv4-range-expander.service.ts
new file mode 100644
index 0000000..893b1d3
--- /dev/null
+++ b/src/tools/ipv4-range-expander/ipv4-range-expander.service.ts
@@ -0,0 +1,63 @@
+import type { Ipv4RangeExpanderResult } from './ipv4-range-expander.types';
+import { convertBase } from '../integer-base-converter/integer-base-converter.model';
+import { ipv4ToInt } from '../ipv4-address-converter/ipv4-address-converter.service';
+export { calculateCidr };
+
+function bits2ip(ipInt: number) {
+  return (ipInt >>> 24) + '.' + ((ipInt >> 16) & 255) + '.' + ((ipInt >> 8) & 255) + '.' + (ipInt & 255);
+}
+
+function getRangesize(start: string, end: string) {
+  if (start == null || end == null) return -1;
+
+  return 1 + parseInt(end, 2) - parseInt(start, 2);
+}
+
+function getCidr(start: string, end: string) {
+  if (start == null || end == null) return null;
+
+  const range = getRangesize(start, end);
+  if (range < 1) {
+    return null;
+  }
+
+  let mask = 32;
+  for (let i = 0; i < 32; i++) {
+    if (start[i] !== end[i]) {
+      mask = i;
+      break;
+    }
+  }
+
+  const newStart = start.substring(0, mask) + '0'.repeat(32 - mask);
+  const newEnd = end.substring(0, mask) + '1'.repeat(32 - mask);
+
+  return { start: newStart, end: newEnd, mask: mask };
+}
+
+function calculateCidr({ startIp, endIp }: { startIp: string; endIp: string }) {
+  const start = convertBase({
+    value: ipv4ToInt({ ip: startIp }).toString(),
+    fromBase: 10,
+    toBase: 2,
+  });
+  const end = convertBase({
+    value: ipv4ToInt({ ip: endIp }).toString(),
+    fromBase: 10,
+    toBase: 2,
+  });
+
+  const cidr = getCidr(start, end);
+  if (cidr != null) {
+    const result: Ipv4RangeExpanderResult = {};
+    result.newEnd = bits2ip(parseInt(cidr.end, 2));
+    result.newStart = bits2ip(parseInt(cidr.start, 2));
+    result.newCidr = result.newStart + '/' + cidr.mask;
+    result.newSize = getRangesize(cidr.start, cidr.end);
+
+    result.oldSize = getRangesize(start, end);
+    return result;
+  }
+
+  return undefined;
+}