classlib: implement java.net.Socket

This patch introduces the implementation of the java.net.Socket class, providing
functionality for creating, connecting, and managing sockets in a WASI-based
environment. Additionally, it includes the implementation of several related
networking classes:
- java.net.ServerSocket
- java.net.InetAddress
- java.net.Inet4Address
- java.net.Inet6Address
- java.net.SocketAddress
- java.net.InetSocketAddress
- java.net.Proxy
- java.net.NetworkInterface
- java.net.SocketException
- java.net.UnknownHostException

Author: mandesero

classlib/src/main/java/org/teavm/classlib/java/net/TInet4Address.java

@@ -0,0 +1,83 @@
+/*
+ *  Copyright 2025 Maksim Tiushev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.net;
+
+public final class TInet4Address extends TInetAddress {
+    static final int INADDRSZ = 4;
+
+    TInet4Address(byte[] addr, String hostname) {
+        super(addr, hostname, IPv4);
+        validateIPv4Address(addr);
+    }
+
+    private static void validateIPv4Address(byte[] addr) {
+        if (addr.length != INADDRSZ) {
+            throw new IllegalArgumentException("IPv4 address must be exactly 4 bytes long.");
+        }
+    }
+
+    @Override
+    public boolean isAnyLocalAddress() {
+        return address[0] == 0 && address[1] == 0 && address[2] == 0 && address[3] == 0;
+    }
+
+    @Override
+    public boolean isLoopbackAddress() {
+        return address[0] == 127;
+    }
+
+    @Override
+    public boolean isLinkLocalAddress() {
+        return (address[0] & 0xFF) == 169 && (address[1] & 0xFF) == 254;
+    }
+
+    @Override
+    public boolean isMCGlobal() {
+        return (address[0] & 0xFF) >= 224
+                && (address[0] & 0xFF) <= 238
+                && !(address[0] == 224 && address[1] == 0 && address[2] == 0);
+    }
+
+    @Override
+    public boolean isMCLinkLocal() {
+        return (address[0] & 0xFF) == 224 && (address[1] & 0xFF) == 0;
+    }
+
+    @Override
+    public boolean isMCOrgLocal() {
+        return (address[0] & 0xFF) == 239 && (address[1] & 0xFF) >= 192;
+    }
+
+    @Override
+    public boolean isMCSiteLocal() {
+        return (address[0] & 0xFF) == 239 && (address[1] & 0xFF) == 255;
+    }
+
+    @Override
+    public boolean isMulticastAddress() {
+        return (address[0] & 0xFF) >= 224 && (address[0] & 0xFF) <= 239;
+    }
+
+    @Override
+    public boolean isSiteLocalAddress() {
+        int firstOctet = address[0] & 0xFF;
+        int secondOctet = address[1] & 0xFF;
+
+        return (firstOctet == 10)
+                || (firstOctet == 172 && secondOctet >= 16 && secondOctet <= 31)
+                || (firstOctet == 192 && secondOctet == 168);
+    }
+}

classlib/src/main/java/org/teavm/classlib/java/net/TInet6Address.java

@@ -0,0 +1,154 @@
+/*
+ *  Copyright 2025 Maksim Tiushev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.net;
+
+public final class TInet6Address extends TInetAddress {
+    static final int INADDRSZ = 16;
+
+    TInet6Address(byte[] addr, String hostname) {
+        super(addr, hostname, IPv6);
+        validateIPv6Address(addr);
+    }
+
+    private static void validateIPv6Address(byte[] addr) {
+        if (addr.length != INADDRSZ) {
+            throw new IllegalArgumentException("IPv6 address must be exactly 16 bytes long.");
+        }
+    }
+
+    @Override
+    public String getHostAddress() {
+        StringBuilder sb = new StringBuilder();
+        int[] segments = new int[8];
+
+        for (int i = 0; i < 8; i++) {
+            segments[i] = ((address[i * 2] & 0xFF) << 8) | (address[i * 2 + 1] & 0xFF);
+        }
+
+        int startZero = -1;
+        int maxZeroLength = 0;
+        int zeroLength = 0;
+        int currentStart = -1;
+        for (int i = 0; i < segments.length; i++) {
+            if (segments[i] == 0) {
+                if (currentStart == -1) {
+                    currentStart = i;
+                }
+                zeroLength++;
+            } else {
+                if (zeroLength > maxZeroLength) {
+                    maxZeroLength = zeroLength;
+                    startZero = currentStart;
+                }
+                zeroLength = 0;
+                currentStart = -1;
+            }
+        }
+        if (zeroLength > maxZeroLength) {
+            maxZeroLength = zeroLength;
+            startZero = currentStart;
+        }
+
+        for (int i = 0; i < segments.length; i++) {
+            if (startZero == i && maxZeroLength > 1) {
+                if (i == 0) {
+                    sb.append("::");
+                } else {
+                    sb.append(':');
+                }
+                i += maxZeroLength - 1;
+                continue;
+            }
+            sb.append(Integer.toHexString(segments[i]));
+            if (i < segments.length - 1) {
+                sb.append(':');
+            }
+        }
+        return sb.toString();
+    }
+
+    @Override
+    public boolean isAnyLocalAddress() {
+        for (byte b : address) {
+            if (b != 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public boolean isIPv4CompatibleAddress() {
+        for (int i = 0; i < 12; i++) {
+            if (address[i] != 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Override
+    public boolean isLinkLocalAddress() {
+        return (address[0] & 0xFF) == 0xFE && (address[1] & 0xC0) == 0x80;
+    }
+
+    @Override
+    public boolean isLoopbackAddress() {
+        if (address[15] != 1) {
+            return false;
+        }
+        for (int i = 0; i < 15; i++) {
+            if (address[i] != 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Override
+    public boolean isMCGlobal() {
+        return (address[0] & 0xFF) == 0xFF && (address[1] & 0x0F) == 0x0E;
+    }
+
+    @Override
+    public boolean isMCLinkLocal() {
+        return (address[0] & 0xFF) == 0xFF && (address[1] & 0x0F) == 0x02;
+    }
+
+    @Override
+    public boolean isMCNodeLocal() {
+        return (address[0] & 0xFF) == 0xFF && (address[1] & 0x0F) == 0x01;
+    }
+
+    @Override
+    public boolean isMCOrgLocal() {
+        return (address[0] & 0xFF) == 0xFF && (address[1] & 0x0F) == 0x08;
+    }
+
+    @Override
+    public boolean isMCSiteLocal() {
+        return (address[0] & 0xFF) == 0xFF && (address[1] & 0x0F) == 0x05;
+    }
+
+    @Override
+    public boolean isMulticastAddress() {
+        return (address[0] & 0xFF) == 0xFF;
+    }
+
+    @Override
+    public boolean isSiteLocalAddress() {
+        return (address[0] & 0xFF) == 0xFE && (address[1] & 0xC0) == 0xC0;
+    }
+}