Fix RDAP quirks uncovered during documentation

There's no reason not to allow a one-character search string when there are no wildcards. And the ROID validity pattern did not allow underscores, which was causing problems with our ROIDs.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=136256605

java/google/registry/rdap/RdapEntityAction.java

@@ -49,7 +49,7 @@ public class RdapEntityAction extends RdapActionBase {
 
   public static final String PATH = "/rdap/entity/";
 
-  private static final Pattern ROID_PATTERN = Pattern.compile("[-.a-zA-Z0-9]+");
+  private static final Pattern ROID_PATTERN = Pattern.compile("[-_.a-zA-Z0-9]+");
 
   @Inject Clock clock;
   @Inject RdapEntityAction() {}

java/google/registry/rdap/RdapJsonFormatter.java

@@ -16,6 +16,7 @@ package google.registry.rdap;
 
 import static com.google.common.base.Strings.nullToEmpty;
 import static google.registry.model.ofy.ObjectifyService.ofy;
+import static google.registry.util.DomainNameUtils.ACE_PREFIX;
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Function;
@@ -1054,6 +1055,7 @@ public class RdapJsonFormatter {
   }
 
   private static boolean hasUnicodeComponents(String fullyQualifiedName) {
-    return fullyQualifiedName.startsWith("xn--") || fullyQualifiedName.contains(".xn--");
+    return fullyQualifiedName.startsWith(ACE_PREFIX)
+        || fullyQualifiedName.contains("." + ACE_PREFIX);
   }
 }

java/google/registry/rdap/RdapSearchPattern.java

@@ -14,6 +14,8 @@
 
 package google.registry.rdap;
 
+import static google.registry.util.DomainNameUtils.ACE_PREFIX;
+
 import google.registry.request.HttpException.UnprocessableEntityException;
 import javax.annotation.Nullable;
 
@@ -82,8 +84,7 @@ public final class RdapSearchPattern {
    * @throws UnprocessableEntityException if {@code pattern} does not meet the requirements of RFC
    *    7482
    */
-  public static RdapSearchPattern create(
+  public static RdapSearchPattern create(String pattern, boolean allowSuffix) {
-      String pattern, boolean allowSuffix) throws UnprocessableEntityException {
     String initialString;
     boolean hasWildcard;
     String suffix;
@@ -112,14 +113,13 @@ public final class RdapSearchPattern {
         suffix = null;
       }
       initialString = pattern.substring(0, wildcardPos);
-    }
+      if (initialString.length() < 2) {
-    if (initialString.length() < 2) {
+        throw new UnprocessableEntityException("At least two characters must be specified");
-      throw new UnprocessableEntityException("At least two characters must be specified");
+      }
-    }
+      if (initialString.startsWith(ACE_PREFIX) && (initialString.length() < 7)) {
-    if (initialString.startsWith("xn--")
+        throw new UnprocessableEntityException(
-        && (initialString.length() < 7)) {
+            "At least seven characters must be specified for punycode domain searches");
-      throw new UnprocessableEntityException(
+      }
-          "At least seven characters must be specified for punycode domain searches");
     }
     return new RdapSearchPattern(initialString, hasWildcard, suffix);
   }

javatests/google/registry/rdap/RdapEntityActionTest.java

@@ -202,8 +202,8 @@ public class RdapEntityActionTest {
 
   @Test
   public void testUnknownEntity_returns404() throws Exception {
-    assertThat(generateActualJson("MISSING-ENTITY")).isEqualTo(
+    assertThat(generateActualJson("_MISSING-ENTITY_")).isEqualTo(
-        generateExpectedJson("MISSING-ENTITY not found", "rdap_error_404.json"));
+        generateExpectedJson("_MISSING-ENTITY_ not found", "rdap_error_404.json"));
     assertThat(response.getStatus()).isEqualTo(404);
   }
 

javatests/google/registry/rdap/RdapSearchPatternTest.java

@@ -72,6 +72,14 @@ public class RdapSearchPatternTest {
     RdapSearchPattern.create("ex*am.lol", true);
   }
 
+  @Test
+  public void testShortString_ok() throws Exception {
+    RdapSearchPattern rdapSearchPattern = RdapSearchPattern.create("e", true);
+    assertThat(rdapSearchPattern.getInitialString()).isEqualTo("e");
+    assertThat(rdapSearchPattern.getHasWildcard()).isFalse();
+    assertThat(rdapSearchPattern.getSuffix()).isNull();
+  }
+
   @Test
   public void testPrefixTooShort_unprocessable() throws Exception {
     thrown.expect(UnprocessableEntityException.class);