[Android] Replace uses of StringJoiner with StringBuilder (#2098)

Description: [StringJoiner](https://developer.android.com/reference/java/util/StringJoiner) was added in Android API level 24 but we still support back to API level 21, so this results in `NoClassDefFoundError` errors on devices running older Android versions. Risk Level: Medium, this code is simple and unit tested. Testing: Existing unit tests Docs Changes: None Release Notes: Added Signed-off-by: JP Simard <jp@jpsim.com>
envoyproxy · Nov 29, 2022 · 62347c7 · 62347c7
1 parent c724ef6
commit 62347c7
Show file tree

Hide file tree

Showing 3 changed files with 50 additions and 7 deletions.
diff --git a/mobile/docs/root/intro/version_history.rst b/mobile/docs/root/intro/version_history.rst
@@ -6,6 +6,9 @@ Pending Release
 
 Bugfixes:
 
+- Android: Fix `NoClassDefFoundError` errors when using `addDNSFallbackNameservers`
+  or `addH2RawDomains` with Android versions older than API level 24.
+
 Features:
 
 - API: added Envoy's response flags to final stream intel (:issue:`#2009 <2009>`)

diff --git a/mobile/library/java/io/envoyproxy/envoymobile/engine/EnvoyConfiguration.java b/mobile/library/java/io/envoyproxy/envoymobile/engine/EnvoyConfiguration.java
@@ -4,7 +4,7 @@
 import java.util.Map;
 import java.util.regex.Pattern;
 import java.util.regex.Matcher;
-import java.util.StringJoiner;
+import java.lang.StringBuilder;
 import javax.annotation.Nullable;
 
 import io.envoyproxy.envoymobile.engine.types.EnvoyHTTPFilterFactory;
@@ -160,20 +160,28 @@ String resolveTemplate(final String templateYAML, final String platformFilterTem
 
     String dnsFallbackNameserversAsString = "[]";
     if (!dnsFallbackNameservers.isEmpty()) {
-      StringJoiner sj = new StringJoiner(",", "[", "]");
+      StringBuilder sb = new StringBuilder("[");
+      String separator = "";
       for (String nameserver : dnsFallbackNameservers) {
-        sj.add(String.format("{\"socket_address\":{\"address\":\"%s\"}}", nameserver));
+        sb.append(separator);
+        separator = ",";
+        sb.append(String.format("{\"socket_address\":{\"address\":\"%s\"}}", nameserver));
       }
-      dnsFallbackNameserversAsString = sj.toString();
+      sb.append("]");
+      dnsFallbackNameserversAsString = sb.toString();
     }
 
     String h2RawDomainsAsString = "[]";
     if (!h2RawDomains.isEmpty()) {
-      StringJoiner sj = new StringJoiner(",", "[", "]");
+      StringBuilder sb = new StringBuilder("[");
+      String separator = "";
       for (String hostname : h2RawDomains) {
-        sj.add(String.format("\"%s\"", hostname));
+        sb.append(separator);
+        separator = ",";
+        sb.append(String.format("\"%s\"", hostname));
       }
-      h2RawDomainsAsString = sj.toString();
+      sb.append("]");
+      h2RawDomainsAsString = sb.toString();
     }
 
     String dnsResolverConfig = String.format(

diff --git a/mobile/test/java/io/envoyproxy/envoymobile/engine/EnvoyConfigurationTest.kt b/mobile/test/java/io/envoyproxy/envoymobile/engine/EnvoyConfigurationTest.kt
@@ -139,4 +139,36 @@ class EnvoyConfigurationTest {
       assertThat(e.message).contains("cannot enable both statsD and gRPC metrics sink")
     }
   }
+
+  @Test
+  fun `resolving multiple h2 raw domains`() {
+    val envoyConfiguration = EnvoyConfiguration(
+      false, "stats.foo.com", null, 123, 234, 345, 456, 321, "[hostname]", listOf("8.8.8.8"), true,
+      true, true, 222, 333, listOf("h2-raw.domain", "h2-raw.domain2"), 567, 678, 910, "v1.2.3", "com.mydomain.myapp",
+      TrustChainVerification.ACCEPT_UNTRUSTED, "[test]",
+      listOf(EnvoyNativeFilterConfig("filter_name", "test_config")), emptyList(), emptyMap()
+    )
+
+    val resolvedTemplate = envoyConfiguration.resolveTemplate(
+      TEST_CONFIG, PLATFORM_FILTER_CONFIG, NATIVE_FILTER_CONFIG
+    )
+
+    assertThat(resolvedTemplate).contains("&h2_raw_domains [\"h2-raw.domain\",\"h2-raw.domain2\"]")
+  }
+
+  @Test
+  fun `resolving multiple dns fallback nameservers`() {
+    val envoyConfiguration = EnvoyConfiguration(
+      false, "stats.foo.com", null, 123, 234, 345, 456, 321, "[hostname]", listOf("8.8.8.8", "1.1.1.1"), true,
+      true, true, 222, 333, listOf("h2-raw.domain", "h2-raw.domain2"), 567, 678, 910, "v1.2.3", "com.mydomain.myapp",
+      TrustChainVerification.ACCEPT_UNTRUSTED, "[test]",
+      listOf(EnvoyNativeFilterConfig("filter_name", "test_config")), emptyList(), emptyMap()
+    )
+
+    val resolvedTemplate = envoyConfiguration.resolveTemplate(
+      TEST_CONFIG, PLATFORM_FILTER_CONFIG, NATIVE_FILTER_CONFIG
+    )
+
+    assertThat(resolvedTemplate).contains("&dns_resolver_config {\"@type\":\"type.googleapis.com/envoy.extensions.network.dns_resolver.cares.v3.CaresDnsResolverConfig\",\"resolvers\":[{\"socket_address\":{\"address\":\"8.8.8.8\"}},{\"socket_address\":{\"address\":\"1.1.1.1\"}}],\"use_resolvers_as_fallback\": true, \"filter_unroutable_families\": true}")
+  }
 }