From 7341ead2aade10ea1b833e94275277658741883a Mon Sep 17 00:00:00 2001
From: Edoardo La Greca
Date: Mon, 18 Aug 2025 21:09:11 +0200
Subject: switch to multi-module project structure

---
 lib/src/main/kotlin/IPAddress.kt | 73 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 lib/src/main/kotlin/IPAddress.kt

(limited to 'lib/src/main/kotlin/IPAddress.kt')

diff --git a/lib/src/main/kotlin/IPAddress.kt b/lib/src/main/kotlin/IPAddress.kt
new file mode 100644
index 0000000..8eb7414
--- /dev/null
+++ b/lib/src/main/kotlin/IPAddress.kt
@@ -0,0 +1,73 @@
+/**
+ * An IP address (v4 or v6).
+ */
+class IPAddress {
+    private var address: Array<UByte>
+    private var is4: Boolean
+
+    /**
+     * @throws NumberFormatException if the IP address follows neither the IPv4 syntax, nor the IPv6 syntax.
+     */
+    constructor(address: String) {
+        if (isAddressV4(address)) {
+            this.is4 = true
+        } else if (isAddressV6(address)) {
+            this.is4 = false
+        } else {
+            throw NumberFormatException()
+        }
+
+        val split4 = address.split('.')
+        val split6 = address.split(':')
+        val bytes: List<UByte>
+        if (this.is4) {
+            bytes = split4.map { it.toUByte(10) }
+        } else {
+            val shorts = split6.map { it.toShort(16) }
+            bytes = shorts.flatMap {
+                listOf(
+                    it.toInt().and(0xFF00).shr(0x08).toUByte(),
+                    it.toInt().and(0x00FF).toUByte()
+                )
+            }
+        }
+        this.address = bytes.toTypedArray()
+    }
+
+    private fun isAddressV4(address: String): Boolean {
+        val split4 = address.split('.')
+        var isOK = split4.size == 4
+        isOK = isOK && split4.size == split4.filter { it.matches(Regex("^[0-9]+$")) }.size
+        return isOK
+    }
+
+    private fun isAddressV6(address: String): Boolean {
+        val split6 = address.split(':')
+        var isOK = split6.size == 8
+        isOK = isOK && split6.size == split6.filter { it.contains(Regex("^[0-9][a-f]+$")) }.size
+        if (isOK) {
+            return true
+        }
+
+        // try with "::"
+        val split6Double = address.split("::")
+        if (split6Double.size != 2) {
+            return false
+        }
+        val omitted = 8 - split6Double[0].split(':').size - split6Double[1].split(':').size
+        if (omitted < 0) {
+            return false
+        }
+        return true
+    }
+
+    override fun toString(): String {
+        val str: String
+        if (this.is4) {
+            str = this.address.joinToString(separator = ".") { it.toString() }
+        } else {
+            str = this.address.joinToString(separator = ":") { it.toString() }
+        }
+        return str
+    }
+}
\ No newline at end of file
-- 
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