[Feature/extensions] Pass REST params and content to extensions

CHANGELOG.md

@@ -104,6 +104,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
  - Adding create component extension point support for AD ([#4517](https://github.com/opensearch-project/OpenSearch/pull/4517))
  - Add getSettings support for AD([#4519](https://github.com/opensearch-project/OpenSearch/pull/4519))
  - Fixed javadoc warning for build failure([#4581](https://github.com/opensearch-project/OpenSearch/pull/4581))
+ - Pass REST params and content to extensions ([#4633](https://github.com/opensearch-project/OpenSearch/pull/4633))
 
 ## [2.x]
 ### Added

server/src/main/java/org/opensearch/extensions/rest/ExtensionRestRequest.java

@@ -0,0 +1,273 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.extensions.rest;
+
+import org.opensearch.common.bytes.BytesReference;
+import org.opensearch.common.io.stream.StreamInput;
+import org.opensearch.common.io.stream.StreamOutput;
+import org.opensearch.common.xcontent.XContentType;
+import org.opensearch.identity.PrincipalIdentifierToken;
+import org.opensearch.rest.RestRequest;
+import org.opensearch.rest.RestRequest.Method;
+import org.opensearch.transport.TransportRequest;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * Request to execute REST actions on extension node.
+ * This contains necessary portions of a {@link RestRequest} object, but does not pass the full request for security concerns.
+ *
+ * @opensearch.api
+ */
+public class ExtensionRestRequest extends TransportRequest {
+
+    private Method method;
+    private String path;
+    private Map<String, String> params;
+    private XContentType xContentType = null;
+    private BytesReference content;
+    // The owner of this request object
+    private PrincipalIdentifierToken principalIdentifierToken;
+
+    // Tracks consumed parameters and content
+    private final Set<String> consumedParams = new HashSet<>();
+    private boolean contentConsumed = false;
+
+    /**
+     * This object can be instantiated given method, uri, params, content and identifier
+     *
+     * @param method of type {@link Method}
+     * @param path the REST path string (excluding the query)
+     * @param params the REST params
+     * @param xContentType the content type, or null for plain text or no content
+     * @param content the REST request content
+     * @param principalIdentifier the owner of this request
+     */
+    public ExtensionRestRequest(
+        Method method,
+        String path,
+        Map<String, String> params,
+        XContentType xContentType,
+        BytesReference content,
+        PrincipalIdentifierToken principalIdentifier
+    ) {
+        this.method = method;
+        this.path = path;
+        this.params = params;
+        this.xContentType = xContentType;
+        this.content = content;
+        this.principalIdentifierToken = principalIdentifier;
+    }
+
+    /**
+     * Instantiate this request from input stream
+     *
+     * @param in Input stream
+     * @throws IOException on failure to read the stream
+     */
+    public ExtensionRestRequest(StreamInput in) throws IOException {
+        super(in);
+        method = in.readEnum(RestRequest.Method.class);
+        path = in.readString();
+        params = in.readMap(StreamInput::readString, StreamInput::readString);
+        if (in.readBoolean()) {
+            xContentType = in.readEnum(XContentType.class);
+        }
+        content = in.readBytesReference();
+        principalIdentifierToken = in.readNamedWriteable(PrincipalIdentifierToken.class);
+    }
+
+    @Override
+    public void writeTo(StreamOutput out) throws IOException {
+        super.writeTo(out);
+        out.writeEnum(method);
+        out.writeString(path);
+        out.writeMap(params, StreamOutput::writeString, StreamOutput::writeString);
+        out.writeBoolean(xContentType != null);
+        if (xContentType != null) {
+            out.writeEnum(xContentType);
+        }
+        out.writeBytesReference(content);
+        out.writeNamedWriteable(principalIdentifierToken);
+    }
+
+    /**
+     * Gets the REST method
+     *
+     * @return This REST request {@link Method} type
+     */
+    public Method method() {
+        return method;
+    }
+
+    /**
+     * Gets the REST path
+     *
+     * @return This REST request's path
+     */
+    public String path() {
+        return path;
+    }
+
+    /**
+     * Gets the full map of params without consuming them. Rest Handlers should use {@link #param(String)} or {@link #param(String, String)}
+     * to get parameter values.
+     *
+     * @return This REST request's params
+     */
+    public Map<String, String> params() {
+        return params;
+    }
+
+    /**
+     * Tests whether a parameter named {@code key} exists.
+     *
+     * @param key The parameter to test.
+     * @return True if there is a value for this parameter.
+     */
+    public boolean hasParam(String key) {
+        return params.containsKey(key);
+    }
+
+    /**
+     * Gets the value of a parameter, consuming it in the process.
+     *
+     * @param key The parameter key
+     * @return The parameter value if it exists, or null.
+     */
+    public String param(String key) {
+        consumedParams.add(key);
+        return params.get(key);
+    }
+
+    /**
+     * Gets the value of a parameter, consuming it in the process.
+     *
+     * @param key The parameter key
+     * @param defaultValue  A value to return if the parameter value doesn't exist.
+     * @return The parameter value if it exists, or the default value.
+     */
+    public String param(String key, String defaultValue) {
+        consumedParams.add(key);
+        return params.getOrDefault(key, defaultValue);
+    }
+
+    /**
+     * Gets the value of a parameter as a long, consuming it in the process.
+     *
+     * @param key The parameter key
+     * @param defaultValue A value to return if the parameter value doesn't exist.
+     * @return The parameter value if it exists, or the default value.
+     */
+    public long paramAsLong(String key, long defaultValue) {
+        String value = param(key);
+        if (value == null) {
+            return defaultValue;
+        }
+        try {
+            return Long.parseLong(value);
+        } catch (NumberFormatException e) {
+            throw new IllegalArgumentException("Unable to parse param '" + key + "' value '" + value + "' to a long.", e);
+        }
+    }
+
+    /**
+     * Returns parameters consumed by {@link #param(String)} or {@link #param(String, String)}.
+     *
+     * @return a list of consumed parameters.
+     */
+    public List<String> consumedParams() {
+        return new ArrayList<>(consumedParams);
+    }
+
+    /**
+     * Gets the content type, if any.
+     *
+     * @return the content type of the {@link #content()}, or null if the context is plain text or if there is no content.
+     */
+    public XContentType getXContentType() {
+        return xContentType;
+    }
+
+    /**
+     * Gets the content.
+     *
+     * @return This REST request's content
+     */
+    public BytesReference content() {
+        contentConsumed = true;
+        return content;
+    }
+
+    /**
+     * Tests whether content exists.
+     *
+     * @return True if there is non-empty content.
+     */
+    public boolean hasContent() {
+        return content.length() > 0;
+    }
+
+    /**
+     * Tests whether content has been consumed.
+     *
+     * @return True if the content was consumed.
+     */
+    public boolean isContentConsumed() {
+        return contentConsumed;
+    }
+
+    /**
+     * @return This REST request issuer's identity token
+     */
+    public PrincipalIdentifierToken getRequestIssuerIdentity() {
+        return principalIdentifierToken;
+    }
+
+    @Override
+    public String toString() {
+        return "ExtensionRestRequest{method="
+            + method
+            + ", path="
+            + path
+            + ", params="
+            + params
+            + ", xContentType="
+            + xContentType
+            + ", contentLength="
+            + content.length()
+            + ", requester="
+            + principalIdentifierToken.getToken()
+            + "}";
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        ExtensionRestRequest that = (ExtensionRestRequest) obj;
+        return Objects.equals(method, that.method)
+            && Objects.equals(path, that.path)
+            && Objects.equals(params, that.params)
+            && Objects.equals(xContentType, that.xContentType)
+            && Objects.equals(content, that.content)
+            && Objects.equals(principalIdentifierToken, that.principalIdentifierToken);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(method, path, params, xContentType, content, principalIdentifierToken);
+    }
+}