Show group invite link in group list

src/main/java/org/asamk/signal/manager/GroupInviteLinkUrl.java

@@ -0,0 +1,140 @@
+package org.asamk.signal.manager;
+
+import com.google.protobuf.ByteString;
+
+import org.signal.storageservice.protos.groups.GroupInviteLink;
+import org.signal.storageservice.protos.groups.local.DecryptedGroup;
+import org.signal.zkgroup.InvalidInputException;
+import org.signal.zkgroup.groups.GroupMasterKey;
+import org.whispersystems.util.Base64UrlSafe;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+
+public final class GroupInviteLinkUrl {
+
+    private static final String GROUP_URL_HOST = "signal.group";
+    private static final String GROUP_URL_PREFIX = "https://" + GROUP_URL_HOST + "/#";
+
+    private final GroupMasterKey groupMasterKey;
+    private final GroupLinkPassword password;
+    private final String url;
+
+    public static GroupInviteLinkUrl forGroup(GroupMasterKey groupMasterKey, DecryptedGroup group) {
+        return new GroupInviteLinkUrl(groupMasterKey,
+                GroupLinkPassword.fromBytes(group.getInviteLinkPassword().toByteArray()));
+    }
+
+    public static boolean isGroupLink(String urlString) {
+        return getGroupUrl(urlString) != null;
+    }
+
+    /**
+     * @return null iff not a group url.
+     * @throws InvalidGroupLinkException If group url, but cannot be parsed.
+     */
+    public static GroupInviteLinkUrl fromUri(String urlString) throws InvalidGroupLinkException, UnknownGroupLinkVersionException {
+        URI uri = getGroupUrl(urlString);
+
+        if (uri == null) {
+            return null;
+        }
+
+        try {
+            if (!"/".equals(uri.getPath()) && uri.getPath().length() > 0) {
+                throw new InvalidGroupLinkException("No path was expected in uri");
+            }
+
+            String encoding = uri.getFragment();
+
+            if (encoding == null || encoding.length() == 0) {
+                throw new InvalidGroupLinkException("No reference was in the uri");
+            }
+
+            byte[] bytes = Base64UrlSafe.decodePaddingAgnostic(encoding);
+            GroupInviteLink groupInviteLink = GroupInviteLink.parseFrom(bytes);
+
+            switch (groupInviteLink.getContentsCase()) {
+                case V1CONTENTS: {
+                    GroupInviteLink.GroupInviteLinkContentsV1 groupInviteLinkContentsV1 = groupInviteLink.getV1Contents();
+                    GroupMasterKey groupMasterKey = new GroupMasterKey(groupInviteLinkContentsV1.getGroupMasterKey()
+                            .toByteArray());
+                    GroupLinkPassword password = GroupLinkPassword.fromBytes(groupInviteLinkContentsV1.getInviteLinkPassword()
+                            .toByteArray());
+
+                    return new GroupInviteLinkUrl(groupMasterKey, password);
+                }
+                default:
+                    throw new UnknownGroupLinkVersionException("Url contains no known group link content");
+            }
+        } catch (InvalidInputException | IOException e) {
+            throw new InvalidGroupLinkException(e);
+        }
+    }
+
+    /**
+     * @return {@link URI} if the host name matches.
+     */
+    private static URI getGroupUrl(String urlString) {
+        try {
+            URI url = new URI(urlString);
+
+            if (!"https".equalsIgnoreCase(url.getScheme()) && !"sgnl".equalsIgnoreCase(url.getScheme())) {
+                return null;
+            }
+
+            return GROUP_URL_HOST.equalsIgnoreCase(url.getHost()) ? url : null;
+        } catch (URISyntaxException e) {
+            return null;
+        }
+    }
+
+    private GroupInviteLinkUrl(GroupMasterKey groupMasterKey, GroupLinkPassword password) {
+        this.groupMasterKey = groupMasterKey;
+        this.password = password;
+        this.url = createUrl(groupMasterKey, password);
+    }
+
+    protected static String createUrl(GroupMasterKey groupMasterKey, GroupLinkPassword password) {
+        GroupInviteLink groupInviteLink = GroupInviteLink.newBuilder()
+                .setV1Contents(GroupInviteLink.GroupInviteLinkContentsV1.newBuilder()
+                        .setGroupMasterKey(ByteString.copyFrom(groupMasterKey.serialize()))
+                        .setInviteLinkPassword(ByteString.copyFrom(password.serialize())))
+                .build();
+
+        String encoding = Base64UrlSafe.encodeBytesWithoutPadding(groupInviteLink.toByteArray());
+
+        return GROUP_URL_PREFIX + encoding;
+    }
+
+    public String getUrl() {
+        return url;
+    }
+
+    public GroupMasterKey getGroupMasterKey() {
+        return groupMasterKey;
+    }
+
+    public GroupLinkPassword getPassword() {
+        return password;
+    }
+
+    public final static class InvalidGroupLinkException extends Exception {
+
+        public InvalidGroupLinkException(String message) {
+            super(message);
+        }
+
+        public InvalidGroupLinkException(Throwable cause) {
+            super(cause);
+        }
+    }
+
+    public final static class UnknownGroupLinkVersionException extends Exception {
+
+        public UnknownGroupLinkVersionException(String message) {
+            super(message);
+        }
+    }
+}

src/main/java/org/asamk/signal/manager/GroupLinkPassword.java

@@ -0,0 +1,40 @@
+package org.asamk.signal.manager;
+
+import java.util.Arrays;
+
+public final class GroupLinkPassword {
+
+    private static final int SIZE = 16;
+
+    private final byte[] bytes;
+
+    public static GroupLinkPassword createNew() {
+        return new GroupLinkPassword(KeyUtils.getSecretBytes(SIZE));
+    }
+
+    public static GroupLinkPassword fromBytes(byte[] bytes) {
+        return new GroupLinkPassword(bytes);
+    }
+
+    private GroupLinkPassword(byte[] bytes) {
+        this.bytes = bytes;
+    }
+
+    public byte[] serialize() {
+        return bytes.clone();
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (!(other instanceof GroupLinkPassword)) {
+            return false;
+        }
+
+        return Arrays.equals(bytes, ((GroupLinkPassword) other).bytes);
+    }
+
+    @Override
+    public int hashCode() {
+        return Arrays.hashCode(bytes);
+    }
+}

src/main/java/org/asamk/signal/manager/KeyUtils.java

@@ -39,7 +39,7 @@ class KeyUtils {
         return Base64.encodeBytes(secret);
     }
 
-    private static byte[] getSecretBytes(int size) {
+    static byte[] getSecretBytes(int size) {
         byte[] secret = new byte[size];
         RandomUtils.getSecureRandom().nextBytes(secret);
         return secret;