From bf25ac607091424b85834c72aba064763aca6e54 Mon Sep 17 00:00:00 2001
From: Roger Hardiman <software@rjh.org.uk>
Date: Sun, 7 Aug 2022 08:29:28 +0100
Subject: [PATCH] Adds a function to generate a range of IPv4 or IPv6 IP
 addresses in an array

---
 README.md        |  5 ++++-
 lib/ip.js        | 39 +++++++++++++++++++++++++++++++++++++++
 test/api-test.js | 23 +++++++++++++++++++++++
 3 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 22e5819..efadbb1 100644
--- a/README.md
+++ b/README.md
@@ -58,10 +58,13 @@ ip.cidrSubnet('192.168.1.134/26')
 // range checking
 ip.cidrSubnet('192.168.1.134/26').contains('192.168.1.190') // true
 
-
 // ipv4 long conversion
 ip.toLong('127.0.0.1'); // 2130706433
 ip.fromLong(2130706433); // '127.0.0.1'
+
+// generate range
+ip.range('192.168.0.1', '192.168.0.4'); // ['192.168.0.1', '192.168.0.2', '192.168.0.3', '192.168.0.4']
+ip.range('::1', '::4'); // ['::1', '::2', '::3', '::4']
 ```
 
 ### License
diff --git a/lib/ip.js b/lib/ip.js
index 4b2adb5..a12395e 100644
--- a/lib/ip.js
+++ b/lib/ip.js
@@ -420,3 +420,42 @@ ip.fromLong = function (ipl) {
     ipl >> 8 & 255}.${
     ipl & 255}`);
 };
+
+
+
+ip.range = function(start, end) {
+  let range = [];
+  if (this.isV4Format(start) && this.isV4Format(end)) {
+    let a = ip.toLong(start);
+    let b = ip.toLong(end);
+    for (let i = a; i <= b; i++) {
+      range.push(ip.fromLong(i));
+    }
+  }
+  else {
+    let a = ip.toBuffer(start);
+    let b = ip.toBuffer(end);
+    // check same format
+    if (a.length === b.length) {
+      // while a <= b
+      while (Buffer.compare(a, b) <= 0) {
+        range.push(ip.toString(a));
+
+        // increment with carry
+        let increment = true;
+        let p = a.length - 1;
+        while (p >= 0 && increment) {
+          if (a[p] === 255) {
+            a[p] = 0;
+            increment = true;
+          } else {
+            a[p]++;
+            increment = false;
+          }
+          p--;
+        }
+      }
+    }
+  }
+  return range;
+};
diff --git a/test/api-test.js b/test/api-test.js
index f0fd222..a30b438 100644
--- a/test/api-test.js
+++ b/test/api-test.js
@@ -413,4 +413,27 @@ describe('IP library for node.js', () => {
       assert.equal(ip.fromLong(4294967295), '255.255.255.255');
     });
   });
+
+  describe('range() method', function() {
+    it('should respond with array of ipv4 addresses', () => {
+      let range_array = ip.range('192.168.0.0', '192.168.1.255');
+      assert.equal(range_array.length, 512);
+      assert.equal(range_array[0], '192.168.0.0');
+      assert.equal(range_array[1], '192.168.0.1');
+      assert.equal(range_array[510], '192.168.1.254');
+      assert.equal(range_array[511], '192.168.1.255');
+    });
+  });
+
+  describe('range() method', function() {
+    it('should respond with array of ipv6 addresses', () => {
+      let range_array = ip.range('2000::fffe', '2000::1:2');
+      assert.equal(range_array.length, 5);
+      assert.equal(range_array[0], '2000::fffe');
+      assert.equal(range_array[1], '2000::ffff');
+      assert.equal(range_array[2], '2000::1:0');
+      assert.equal(range_array[3], '2000::1:1');
+      assert.equal(range_array[4], '2000::1:2');
+    });
+  });
 });