Add an abusive message filter interface and submodule

service/src/main/java/org/whispersystems/textsecuregcm/abuse/AbusiveMessageFilter.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2013-2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.abuse;
+
+import io.dropwizard.lifecycle.Managed;
+import javax.ws.rs.container.ContainerRequestFilter;
+import java.io.IOException;
+
+/**
+ * An abusive message filter is a {@link ContainerRequestFilter} that filters requests to message-sending endpoints to
+ * detect and respond to patterns of abusive behavior.
+ * <p/>
+ * Abusive message filters are managed components that are generally loaded dynamically via a
+ * {@link java.util.ServiceLoader}. Their {@link #configure(String)} method will be called prior to be adding to the
+ * server's pool of {@link Managed} objects.
+ * <p/>
+ * Abusive message filters must be annotated with {@link FilterAbusiveMessages}, a name binding annotation that
+ * restricts the endpoints to which the filter may apply.
+ */
+public interface AbusiveMessageFilter extends ContainerRequestFilter, Managed {
+
+  /**
+   * Configures this abusive message filter. This method will be called before the filter is added to the server's pool
+   * of managed objects and before the server processes any requests.
+   *
+   * @param environmentName the name of the environment in which this filter is running (e.g. "staging" or "production")
+   * @throws IOException if the filter could not read its configuration source for any reason
+   */
+  void configure(String environmentName) throws IOException;
+}

service/src/main/java/org/whispersystems/textsecuregcm/abuse/FilterAbusiveMessages.java

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+/*
+ * Copyright 2013-2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.abuse;
+
+import javax.ws.rs.NameBinding;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * A name-binding annotation that associates {@link AbusiveMessageFilter}s with resource methods.
+ */
+@NameBinding
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.TYPE, ElementType.METHOD})
+public @interface FilterAbusiveMessages {
+}