From c09dbfa47c50b2d316705b49d759eb492af4813b Mon Sep 17 00:00:00 2001
From: Greyson Parrelli <greyson@signal.org>
Date: Thu, 27 Aug 2020 10:52:47 -0400
Subject: [PATCH] Prevent corner-case where link previews were generated for
 SMS.

Also added some hardening to make sure that it's impossible for any link
previews to be fetched if the setting is disabled (this was already the
case in practice, we just have some assertions in there now).

Fixes #9956
---
 .../conversation/ConversationActivity.java    |  3 +-
 .../linkpreview/LinkPreviewViewModel.java     | 35 +++++++++++++++----
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java
index fcedbdba5..02771d15d 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java
@@ -1840,6 +1840,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
     sendButton.addOnTransportChangedListener((newTransport, manuallySelected) -> {
       calculateCharactersRemaining();
       updateLinkPreviewState();
+      linkPreviewViewModel.onTransportChanged(newTransport.isSms());
       composeText.setTransport(newTransport);
 
       buttonToggle.getBackground().setColorFilter(newTransport.getBackgroundColor(), PorterDuff.Mode.MULTIPLY);
@@ -2692,7 +2693,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
   }
 
   private void updateLinkPreviewState() {
-    if (SignalStore.settings().isLinkPreviewsEnabled() && !sendButton.getSelectedTransport().isSms() && !attachmentManager.isAttachmentPresent()) {
+    if (SignalStore.settings().isLinkPreviewsEnabled() && isSecureText && !sendButton.getSelectedTransport().isSms() && !attachmentManager.isAttachmentPresent()) {
       linkPreviewViewModel.onEnabled();
       linkPreviewViewModel.onTextChanged(this, composeText.getTextTrimmed().toString(), composeText.getSelectionStart(), composeText.getSelectionEnd());
     } else {
diff --git a/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java b/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java
index fe34eebd1..5ec5f0b77 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java
+++ b/app/src/main/java/org/thoughtcrime/securesms/linkpreview/LinkPreviewViewModel.java
@@ -7,9 +7,11 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.Transformations;
 import androidx.lifecycle.ViewModel;
 import androidx.lifecycle.ViewModelProvider;
 
+import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.net.RequestController;
 import org.thoughtcrime.securesms.util.Debouncer;
 import org.thoughtcrime.securesms.util.Util;
@@ -23,32 +25,36 @@ public class LinkPreviewViewModel extends ViewModel {
 
   private final LinkPreviewRepository             repository;
   private final MutableLiveData<LinkPreviewState> linkPreviewState;
+  private final LiveData<LinkPreviewState>        linkPreviewSafeState;
 
   private String            activeUrl;
   private RequestController activeRequest;
   private boolean           userCanceled;
   private Debouncer         debouncer;
+  private boolean           enabled;
 
   private LinkPreviewViewModel(@NonNull LinkPreviewRepository repository) {
-    this.repository       = repository;
-    this.linkPreviewState = new MutableLiveData<>();
-    this.debouncer        = new Debouncer(250);
+    this.repository           = repository;
+    this.linkPreviewState     = new MutableLiveData<>();
+    this.debouncer            = new Debouncer(250);
+    this.enabled              = SignalStore.settings().isLinkPreviewsEnabled();
+    this.linkPreviewSafeState = Transformations.map(linkPreviewState, state -> enabled ? state : LinkPreviewState.forNoLinks());
   }
 
   public LiveData<LinkPreviewState> getLinkPreviewState() {
-    return linkPreviewState;
+    return linkPreviewSafeState;
   }
 
   public boolean hasLinkPreview() {
-    return linkPreviewState.getValue() != null && linkPreviewState.getValue().getLinkPreview().isPresent();
+    return linkPreviewSafeState.getValue() != null && linkPreviewSafeState.getValue().getLinkPreview().isPresent();
   }
 
   public boolean hasLinkPreviewUi() {
-    return linkPreviewState.getValue() != null && linkPreviewState.getValue().hasContent();
+    return linkPreviewSafeState.getValue() != null && linkPreviewSafeState.getValue().hasContent();
   }
 
   public @NonNull List<LinkPreview> getActiveLinkPreviews() {
-    final LinkPreviewState state = linkPreviewState.getValue();
+    final LinkPreviewState state = linkPreviewSafeState.getValue();
 
     if (state == null || !state.getLinkPreview().isPresent()) {
       return Collections.emptyList();
@@ -58,6 +64,8 @@ public class LinkPreviewViewModel extends ViewModel {
   }
 
   public void onTextChanged(@NonNull Context context, @NonNull String text, int cursorStart, int cursorEnd) {
+    if (!enabled) return;
+
     debouncer.publish(() -> {
       if (TextUtils.isEmpty(text)) {
         userCanceled = false;
@@ -129,6 +137,14 @@ public class LinkPreviewViewModel extends ViewModel {
     linkPreviewState.setValue(LinkPreviewState.forNoLinks());
   }
 
+  public void onTransportChanged(boolean isSms) {
+    enabled = !isSms;
+
+    if (isSms) {
+      onUserCancel();
+    }
+  }
+
   public void onSend() {
     if (activeRequest != null) {
       activeRequest.cancel();
@@ -143,7 +159,12 @@ public class LinkPreviewViewModel extends ViewModel {
   }
 
   public void onEnabled() {
+    if (!SignalStore.settings().isLinkPreviewsEnabled()) {
+      throw new AssertionError();
+    }
+
     userCanceled = false;
+    enabled      = true;
   }
 
   @Override