Add deep cross-platform calendar integration

CodenameOne/src/com/codename1/calendar/CalDavAuthentication.java

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+/*
+ * Copyright (c) 2026, Codename One and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Codename One designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Codename One through http://www.codenameone.com/ if you
+ * need additional information or have any questions.
+ */
+package com.codename1.calendar;
+
+import com.codename1.security.Hash;
+import com.codename1.util.AsyncResource;
+import com.codename1.util.Base64;
+import com.codename1.util.StringUtil;
+import com.codename1.util.SuccessCallback;
+import java.util.HashMap;
+import java.util.Map;
+
+/// App-owned CalDAV authentication strategy. Built-in strategies cover Basic,
+/// OAuth Bearer, and RFC 7616 Digest authentication.
+public abstract class CalDavAuthentication {
+
+    public abstract AsyncResource<String> authorization(String method, String uri, String challenge, boolean forceRefresh);
+
+    public static CalDavAuthentication basic(final String username, final String password) {
+        if (username == null || password == null) {
+            throw new IllegalArgumentException("username and password required");
+        }
+        return new CalDavAuthentication() {
+
+            @Override
+            public AsyncResource<String> authorization(String method, String uri, String challenge, boolean forceRefresh) {
+                return complete("Basic " + Base64.encodeNoNewline(StringUtil.getBytes(username + ":" + password)));
+            }
+        };
+    }
+
+    public static CalDavAuthentication bearer(final CalendarTokenProvider tokens, final String... scopes) {
+        if (tokens == null) {
+            throw new IllegalArgumentException("token provider required");
+        }
+        return new CalDavAuthentication() {
+
+            @Override
+            public AsyncResource<String> authorization(String method, String uri, String challenge, boolean forceRefresh) {
+                final AsyncResource<String> out = new AsyncResource<String>();
+                tokens.getToken(scopes, forceRefresh).ready(new SuccessCallback<CalendarAuthToken>() {
+
+                    @Override
+                    public void onSucess(CalendarAuthToken token) {
+                        out.complete("Bearer " + token.getAccessToken());
+                    }
+                }).except(new SuccessCallback<Throwable>() {
+
+                    @Override
+                    public void onSucess(Throwable error) {
+                        out.error(error);
+                    }
+                });
+                return out;
+            }
+        };
+    }
+
+    public static CalDavAuthentication digest(final String username, final String password) {
+        if (username == null || password == null) {
+            throw new IllegalArgumentException("username and password required");
+        }
+        return new Digest(username, password);
+    }
+
+    private static final class Digest extends CalDavAuthentication {
+
+        private final String username;
+
+        private final String password;
+
+        private int nonceCount;
+
+        Digest(String username, String password) {
+            this.username = username;
+            this.password = password;
+        }
+
+        @Override
+        public synchronized AsyncResource<String> authorization(String method, String uri, String challenge, boolean forceRefresh) {
+            if (challenge == null || !challenge.toLowerCase().startsWith("digest ")) {
+                return complete(null);
+            }
+            Map<String, String> p = parse(challenge.substring(7));
+            String realm = p.get("realm");
+            String nonce = p.get("nonce");
+            String opaque = p.get("opaque");
+            String qop = selectQop(p.get("qop"));
+            if (realm == null || nonce == null) {
+                return failed(new CalendarException(CalendarError.AUTHENTICATION_REQUIRED, "Invalid Digest challenge"));
+            }
+            String algorithm = p.get("algorithm");
+            if (algorithm != null && !"MD5".equalsIgnoreCase(algorithm) && !"MD5-sess".equalsIgnoreCase(algorithm)) {
+                return failed(new CalendarException(CalendarError.NOT_SUPPORTED, "Digest algorithm " + algorithm + " is not supported"));
+            }
+            String nc = hex(++nonceCount, 8);
+            String cnonce = md5(String.valueOf(System.currentTimeMillis()) + ":" + nonceCount).substring(0, 16);
+            String ha1 = md5(username + ":" + realm + ":" + password);
+            if ("MD5-sess".equalsIgnoreCase(algorithm)) {
+                ha1 = md5(ha1 + ":" + nonce + ":" + cnonce);
+            }
+            String ha2 = md5(method + ":" + uri);
+            String response = qop == null ? md5(ha1 + ":" + nonce + ":" + ha2) : md5(ha1 + ":" + nonce + ":" + nc + ":" + cnonce + ":" + qop + ":" + ha2);
+            StringBuilder out = new StringBuilder("Digest username=\"").append(escape(username)).append("\", realm=\"").append(escape(realm)).append("\", nonce=\"").append(escape(nonce)).append("\", uri=\"").append(escape(uri)).append("\", response=\"").append(response).append('"');
+            if (algorithm != null) {
+                out.append(", algorithm=").append(algorithm);
+            }
+            if (opaque != null) {
+                out.append(", opaque=\"").append(escape(opaque)).append('"');
+            }
+            if (qop != null) {
+                out.append(", qop=").append(qop).append(", nc=").append(nc).append(", cnonce=\"").append(cnonce).append('"');
+            }
+            return complete(out.toString());
+        }
+    }
+
+    private static Map<String, String> parse(String value) {
+        Map<String, String> out = new HashMap<String, String>();
+        int i = 0;
+        while (i < value.length()) {
+            while (i < value.length() && (value.charAt(i) == ' ' || value.charAt(i) == ',')) {
+                i++;
+            }
+            int eq = value.indexOf('=', i);
+            if (eq < 0) {
+                break;
+            }
+            String key = value.substring(i, eq).trim().toLowerCase();
+            i = eq + 1;
+            String data;
+            if (i < value.length() && value.charAt(i) == '"') {
+                i++;
+                StringBuilder b = new StringBuilder();
+                while (i < value.length()) {
+                    char c = value.charAt(i++);
+                    if (c == '"') {
+                        break;
+                    }
+                    if (c == '\\' && i < value.length()) {
+                        c = value.charAt(i++);
+                    }
+                    b.append(c);
+                }
+                data = b.toString();
+            } else {
+                int comma = value.indexOf(',', i);
+                if (comma < 0) {
+                    comma = value.length();
+                }
+                data = value.substring(i, comma).trim();
+                i = comma;
+            }
+            out.put(key, data);
+        }
+        return out;
+    }
+
+    private static String selectQop(String qop) {
+        if (qop == null) {
+            return null;
+        }
+        for (String v : CalendarDateUtil.split(qop, ',')) {
+            if ("auth".equalsIgnoreCase(v.trim())) {
+                return "auth";
+            }
+        }
+        return null;
+    }
+
+    private static String md5(String value) {
+        Hash hash = Hash.create(Hash.MD5);
+        hash.update(StringUtil.getBytes(value));
+        byte[] bytes = hash.digest();
+        StringBuilder out = new StringBuilder();
+        for (byte b : bytes) {
+            out.append(hex(b & 255, 2));
+        }
+        return out.toString();
+    }
+
+    private static String hex(int value, int width) {
+        String s = Integer.toHexString(value);
+        while (s.length() < width) {
+            s = "0" + s;
+        }
+        return s;
+    }
+
+    private static String escape(String value) {
+        return value.replace("\\", "\\\\").replace("\"", "\\\"");
+    }
+
+    private static <T> AsyncResource<T> complete(T value) {
+        AsyncResource<T> out = new AsyncResource<T>();
+        out.complete(value);
+        return out;
+    }
+
+    private static <T> AsyncResource<T> failed(Throwable error) {
+        AsyncResource<T> out = new AsyncResource<T>();
+        out.error(error);
+        return out;
+    }
+}