1 files changed, 150 insertions, 0 deletions
diff --git a/modules/ri-base/src/main/java/io/trygvis/rules/network/Ipv4Cidr.java b/modules/ri-base/src/main/java/io/trygvis/rules/network/Ipv4Cidr.java
new file mode 100644
index 0000000..851af95
--- /dev/null
+++ b/modules/ri-base/src/main/java/io/trygvis/rules/network/Ipv4Cidr.java
@@ -0,0 +1,150 @@
+package io.trygvis.rules.network;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+@JsonSerialize(using = Ipv4Cidr.Serializer.class)
+public class Ipv4Cidr implements Comparable<Ipv4Cidr> {
+    public final int network;
+    public final int bits;
+
+    public Ipv4Cidr(int network, int bits) {
+        if (bits < 0 || bits > 32) {
+            throw new IllegalArgumentException("bits must be [0, 32]");
+        }
+
+        int hostBits = 32 - bits;
+        int netmask = (-1 >> hostBits) << hostBits;
+
+        int x = network & ~netmask;
+
+        if (x != 0) {
+            throw new IllegalArgumentException("The host part of the address must be 0.");
+        }
+
+        this.network = network;
+        this.bits = bits;
+    }
+
+    @Override
+    public String toString() {
+        return "%d.%d.%d.%d/%d".formatted(
+                network >> 24 & 0xff,
+                network >> 16 & 0xff,
+                network >> 8 & 0xff,
+                network & 0xff,
+                bits);
+    }
+
+    private String formatIpv4(int address) {
+        return "%d.%d.%d.%d".formatted(address >> 24 & 0xff, address >> 16 & 0xff, address >> 8 & 0xff, address & 0xff);
+    }
+
+    public List<Ipv4Cidr> partition(int bits) {
+        if (bits <= 0 || bits <= this.bits || bits > 32) {
+            throw new IllegalArgumentException("Invalid new network size");
+        }
+
+        var list = new ArrayList<Ipv4Cidr>();
+
+        int count = 1 << (bits - this.bits);
+        for (int i = 0; i < count; i++) {
+            var network = this.network | (i << (32 - bits));
+
+            list.add(new Ipv4Cidr(network, bits));
+        }
+
+        return list;
+    }
+
+    public List<Ipv4Address> addresses() {
+        int size = 1 << 32 - bits;
+        var end = network + size;
+        var addresses = new ArrayList<Ipv4Address>(size);
+        for (int address = network; address < end; address++) {
+            addresses.add(new Ipv4Address(address));
+        }
+
+        return addresses;
+    }
+
+    @Override
+    public int compareTo(Ipv4Cidr o) {
+        if (this == o) {
+            return 0;
+        }
+
+        var ret = network - o.network;
+        if (ret != 0) {
+            return ret;
+        }
+
+        return bits - o.bits;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Ipv4Cidr ipv4Cidr = (Ipv4Cidr) o;
+        return network == ipv4Cidr.network && bits == ipv4Cidr.bits;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(network, bits);
+    }
+
+    private static final Pattern pattern = Pattern.compile("([0-9]{1,3})\\.([0-9]{1,3})\\.([0-9]{1,3})\\.([0-9]{1,3})/([0-9]{1,3})");
+
+    public static Ipv4Cidr parseCidr(String cidr) {
+        var matcher = pattern.matcher(cidr);
+        if (!matcher.matches()) {
+            throw new IllegalArgumentException("Not a CIDR: " + cidr);
+        }
+
+        var b1 = matcher.group(1);
+        var b2 = matcher.group(2);
+        var b3 = matcher.group(3);
+        var b4 = matcher.group(4);
+
+        int network = parse(b1) << 24 |
+                parse(b2) << 16 |
+                parse(b3) << 8 |
+                parse(b4);
+
+//        System.out.printf("network = %x%n", network);
+
+        var l = matcher.group(5);
+        var bits = Integer.parseInt(l);
+//        System.out.printf("netmask = %08x%n", netmask);
+
+        return new Ipv4Cidr(network, bits);
+    }
+
+    private static int parse(String s) {
+        var i = Integer.parseInt(s);
+        if (i > 255) {
+            throw new IllegalArgumentException("Not a CIDR");
+        }
+
+        return i;
+    }
+
+    public static class Serializer extends JsonSerializer<Ipv4Cidr> {
+        @Override
+        public void serialize(Ipv4Cidr value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
+            gen.writeStartObject();
+            gen.writeObjectField("value", value.toString());
+            gen.writeEndObject();
+        }
+    }
+}