nmode's Git Repositories - signal-cli/blob - lib/src/main/java/org/asamk/signal/manager/api/UsernameLinkUrl.java

   1 package org.asamk.signal.manager.api;
   2
   3 import org.signal.core.util.Base64;
   4 import org.whispersystems.signalservice.api.push.UsernameLinkComponents;
   5 import org.whispersystems.signalservice.api.util.UuidUtil;
   6
   7 import java.io.IOException;
   8 import java.util.Arrays;
   9 import java.util.regex.Pattern;
  10
  11 public final class UsernameLinkUrl {
  12
  13     private static final Pattern URL_REGEX = Pattern.compile("(https://)?signal.me/?#eu/([a-zA-Z0-9+\\-_/]+)");
  14
  15     private static final String BASE_URL = "https://signal.me/#eu/";
  16
  17     private final String url;
  18     private final UsernameLinkComponents usernameLinkComponents;
  19
  20     public static UsernameLinkUrl fromUri(String url) throws InvalidUsernameLinkException {
  21         final var matcher = URL_REGEX.matcher(url);
  22         if (!matcher.matches()) {
  23             throw new InvalidUsernameLinkException("Invalid username link");
  24         }
  25         final var path = matcher.group(2);
  26         final byte[] allBytes;
  27         try {
  28             allBytes = Base64.decode(path);
  29         } catch (IOException e) {
  30             throw new InvalidUsernameLinkException("Invalid base64 encoding");
  31         }
  32
  33         if (allBytes.length != 48) {
  34             throw new InvalidUsernameLinkException("Invalid username link");
  35         }
  36
  37         final var entropy = Arrays.copyOfRange(allBytes, 0, 32);
  38         final var serverId = Arrays.copyOfRange(allBytes, 32, allBytes.length);
  39         final var serverIdUuid = UuidUtil.parseOrNull(serverId);
  40         if (serverIdUuid == null) {
  41             throw new InvalidUsernameLinkException("Invalid serverId");
  42         }
  43
  44         return new UsernameLinkUrl(new UsernameLinkComponents(entropy, serverIdUuid));
  45     }
  46
  47     public UsernameLinkUrl(UsernameLinkComponents usernameLinkComponents) {
  48         this.usernameLinkComponents = usernameLinkComponents;
  49         this.url = createUrl(usernameLinkComponents);
  50     }
  51
  52     private static String createUrl(UsernameLinkComponents usernameLinkComponents) {
  53         final var entropy = usernameLinkComponents.getEntropy();
  54         final var serverId = UuidUtil.toByteArray(usernameLinkComponents.getServerId());
  55
  56         final var combined = new byte[entropy.length + serverId.length];
  57         System.arraycopy(entropy, 0, combined, 0, entropy.length);
  58         System.arraycopy(serverId, 0, combined, entropy.length, serverId.length);
  59
  60         final var base64 = Base64.encodeUrlSafeWithoutPadding(combined);
  61         return BASE_URL + base64;
  62     }
  63
  64     public String getUrl() {
  65         return url;
  66     }
  67
  68     public UsernameLinkComponents getComponents() {
  69         return usernameLinkComponents;
  70     }
  71
  72     public static final class InvalidUsernameLinkException extends Exception {
  73
  74         public InvalidUsernameLinkException(String message) {
  75             super(message);
  76         }
  77
  78         public InvalidUsernameLinkException(Throwable cause) {
  79             super(cause);
  80         }
  81     }
  82 }