Filter strings that cannot be parsed as Regex no longer cause an SDK crash (#4213)

* Fix exception when creating FilterString from string that cannot be parsed as regex

* changelog

Author: adinauer

CHANGELOG.md

@@ -20,6 +20,9 @@
 
 ### Fixes
 
+- Filter strings that cannot be parsed as Regex no longer cause an SDK crash ([#4213](https://github.com/getsentry/sentry-java/pull/4213))
+  - This was the case e.g. for `ignoredErrors`, `ignoredTransactions` and `ignoredCheckIns`
+  - We now simply don't use such strings for Regex matching and only use them for String comparison
 - `SentryOptions.setTracePropagationTargets` is no longer marked internal ([#4170](https://github.com/getsentry/sentry-java/pull/4170))
 - Session Replay: Fix crash when a navigation breadcrumb does not have "to" destination ([#4185](https://github.com/getsentry/sentry-java/pull/4185))
 - Session Replay: Cap video segment duration to maximum 5 minutes to prevent endless video encoding in background ([#4185](https://github.com/getsentry/sentry-java/pull/4185))

sentry/src/main/java/io/sentry/FilterString.java

@@ -3,21 +3,37 @@
 import java.util.Objects;
 import java.util.regex.Pattern;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 public final class FilterString {
   private final @NotNull String filterString;
-  private final @NotNull Pattern pattern;
+  private final @Nullable Pattern pattern;
 
   public FilterString(@NotNull String filterString) {
     this.filterString = filterString;
-    this.pattern = Pattern.compile(filterString);
+    @Nullable Pattern pattern = null;
+    try {
+      pattern = Pattern.compile(filterString);
+    } catch (Throwable t) {
+      Sentry.getCurrentScopes()
+          .getOptions()
+          .getLogger()
+          .log(
+              SentryLevel.DEBUG,
+              "Only using filter string for String comparison as it could not be parsed as regex: %s",
+              filterString);
+    }
+    this.pattern = pattern;
   }
 
   public @NotNull String getFilterString() {
     return filterString;
   }
 
   public boolean matches(String input) {
+    if (pattern == null) {
+      return false;
+    }
     return pattern.matcher(input).matches();
   }
 

sentry/src/test/java/io/sentry/FilterStringTest.kt

@@ -0,0 +1,24 @@
+package io.sentry
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class FilterStringTest {
+
+    @Test
+    fun `turns string into pattern`() {
+        val filterString = FilterString(".*")
+        assertTrue(filterString.matches("anything"))
+        assertEquals(".*", filterString.filterString)
+    }
+
+    @Test
+    fun `skips pattern if not a valid regex`() {
+        // does not throw if the string is not a valid pattern
+        val filterString = FilterString("I love my mustache {")
+        assertFalse(filterString.matches("I love my mustache {"))
+        assertEquals("I love my mustache {", filterString.filterString)
+    }
+}