From 3f7dd2118654516aea26cd87e095a4ad87d2a606 Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Mon, 17 Aug 2020 10:27:26 -0400
Subject: [PATCH] Do not attempt to create link previews for .onion links.

---
 .../linkpreview/LinkPreviewUtil.java          | 28 ++++++++++++++++---
 .../LinkPreviewUtilTest_isLegal.java          |  1 +
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtil.java b/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtil.java
index b1fb95ccb..be20b0c7c 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtil.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtil.java
@@ -11,6 +11,7 @@ import android.text.style.URLSpan;
 import android.text.util.Linkify;
 
 import com.annimon.stream.Stream;
+import com.google.android.collect.Sets;
 
 import org.thoughtcrime.securesms.stickers.StickerUrl;
 import org.thoughtcrime.securesms.util.Util;
@@ -21,6 +22,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -37,6 +39,8 @@ public final class LinkPreviewUtil {
   private static final Pattern FAVICON_PATTERN            = Pattern.compile("<\\s*link[^>]*rel\\s*=\\s*\".*icon.*\"[^>]*>");
   private static final Pattern FAVICON_HREF_PATTERN       = Pattern.compile("href\\s*=\\s*\"([^\"]*)\"");
 
+  private static final Set<String> INVALID_TOP_LEVEL_DOMAINS = Sets.newHashSet("onion");
+
   /**
    * @return All whitelisted URLs in the source text.
    */
@@ -72,11 +76,16 @@ public final class LinkPreviewUtil {
     Matcher matcher = DOMAIN_PATTERN.matcher(url);
 
     if (matcher.matches()) {
-      String domain        = matcher.group(2);
-      String cleanedDomain = domain.replaceAll("\\.", "");
+      String domain         = matcher.group(2);
+      String cleanedDomain  = domain.replaceAll("\\.", "");
+      String topLevelDomain = parseTopLevelDomain(domain);
 
-      return ALL_ASCII_PATTERN.matcher(cleanedDomain).matches() ||
-             ALL_NON_ASCII_PATTERN.matcher(cleanedDomain).matches();
+      boolean validCharacters = ALL_ASCII_PATTERN.matcher(cleanedDomain).matches() ||
+                                ALL_NON_ASCII_PATTERN.matcher(cleanedDomain).matches();
+
+      boolean validTopLevelDomain = !INVALID_TOP_LEVEL_DOMAINS.contains(topLevelDomain);
+
+      return validCharacters &&  validTopLevelDomain;
     } else {
       return false;
     }
@@ -127,6 +136,17 @@ public final class LinkPreviewUtil {
     return new OpenGraph(openGraphTags, htmlTitle, faviconUrl);
   }
 
+  private static @Nullable String parseTopLevelDomain(@NonNull String domain) {
+    int periodIndex = domain.lastIndexOf(".");
+
+    if (periodIndex >= 0 && periodIndex < domain.length() - 1) {
+      return domain.substring(periodIndex + 1);
+    } else {
+      return null;
+    }
+  }
+
+
   public static final class OpenGraph {
 
     private final Map<String, String> values;
diff --git a/app/src/test/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtilTest_isLegal.java b/app/src/test/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtilTest_isLegal.java
index 905337f5f..0cf3f49c7 100644
--- a/app/src/test/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtilTest_isLegal.java
+++ b/app/src/test/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewUtilTest_isLegal.java
@@ -28,6 +28,7 @@ public class LinkPreviewUtilTest_isLegal {
         { "кц.com",                                false },
         { "http://asĸ.com",                        false },
         { "http://foo.кц.рф",                      false },
+        { "https://abcdefg.onion",                 false },
         { "",                                      false }
     });
   }