Fix MinecraftChannelIdentifier parsing to align with vanilla (#1552)

api/src/main/java/com/velocitypowered/api/proxy/messages/MinecraftChannelIdentifier.java

@@ -11,7 +11,6 @@ import static com.google.common.base.Preconditions.checkArgument;
 
 import com.google.common.base.Strings;
 import java.util.Objects;
-import java.util.regex.Pattern;
 import net.kyori.adventure.key.Key;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -21,8 +20,6 @@ import org.checkerframework.checker.nullness.qual.Nullable;
  */
 public final class MinecraftChannelIdentifier implements ChannelIdentifier {
 
-  private static final Pattern VALID_IDENTIFIER_REGEX = Pattern.compile("[a-z0-9/\\-_]*");
-
   private final String namespace;
   private final String name;
 
@@ -39,7 +36,7 @@ public final class MinecraftChannelIdentifier implements ChannelIdentifier {
    * @return a new channel identifier
    */
   public static MinecraftChannelIdentifier forDefaultNamespace(String name) {
-    return new MinecraftChannelIdentifier("minecraft", name);
+    return new MinecraftChannelIdentifier(Key.MINECRAFT_NAMESPACE, name);
   }
 
   /**
@@ -52,14 +49,10 @@ public final class MinecraftChannelIdentifier implements ChannelIdentifier {
   public static MinecraftChannelIdentifier create(String namespace, String name) {
     checkArgument(!Strings.isNullOrEmpty(namespace), "namespace is null or empty");
     checkArgument(name != null, "namespace is null or empty");
-    checkArgument(VALID_IDENTIFIER_REGEX.matcher(namespace).matches(),
-        "namespace is not valid, must match: %s got %s",
-        VALID_IDENTIFIER_REGEX.toString(),
-        namespace);
-    checkArgument(VALID_IDENTIFIER_REGEX.matcher(name).matches(),
-        "name is not valid, must match: %s got %s",
-        VALID_IDENTIFIER_REGEX.toString(),
-        name);
+    checkArgument(Key.parseableNamespace(namespace),
+        "namespace is not valid, must match: [a-z0-9_.-] got %s", namespace);
+    checkArgument(Key.parseableValue(name),
+        "name is not valid, must match: [a-z0-9/._-] got %s", name);
     return new MinecraftChannelIdentifier(namespace, name);
   }
 
@@ -72,10 +65,9 @@ public final class MinecraftChannelIdentifier implements ChannelIdentifier {
   public static MinecraftChannelIdentifier from(String identifier) {
     int colonPos = identifier.indexOf(':');
     if (colonPos == -1) {
-      throw new IllegalArgumentException("Identifier does not contain a colon.");
-    }
-    if (colonPos + 1 == identifier.length()) {
-      throw new IllegalArgumentException("Identifier is empty.");
+      return create(Key.MINECRAFT_NAMESPACE, identifier);
+    } else if (colonPos == 0) {
+      return create(Key.MINECRAFT_NAMESPACE, identifier.substring(1));
     }
     String namespace = identifier.substring(0, colonPos);
     String name = identifier.substring(colonPos + 1);

api/src/test/java/com/velocitypowered/api/proxy/messages/MinecraftChannelIdentifierTest.java

@@ -47,17 +47,25 @@ class MinecraftChannelIdentifierTest {
     create("velocity", "test/test2");
   }
 
+  @Test
+  void fromIdentifierDefaultNamespace() {
+    assertEquals("minecraft", from("test").getNamespace());
+    assertEquals("minecraft", from(":test").getNamespace());
+  }
+
+  @Test
+  void fromIdentifierAllowsEmptyName() {
+    from("minecraft:");
+    from(":");
+    from("");
+  }
+
   @Test
   void fromIdentifierThrowsOnBadValues() {
     assertAll(
-        () -> assertThrows(IllegalArgumentException.class, () -> from("")),
-        () -> assertThrows(IllegalArgumentException.class, () -> from(":")),
-        () -> assertThrows(IllegalArgumentException.class, () -> from(":a")),
-        () -> assertThrows(IllegalArgumentException.class, () -> from("a:")),
         () -> assertThrows(IllegalArgumentException.class, () -> from("hello:$$$$$$")),
+        () -> assertThrows(IllegalArgumentException.class, () -> from("he/llo:wor/ld")),
         () -> assertThrows(IllegalArgumentException.class, () -> from("hello::"))
     );
   }
-
-
-}
+}