content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License. You may obtain a copy of the License at
   *
   *    http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.kafka.connect.runtime.rest;
  
  import org.apache.kafka.connect.errors.ConnectException;
  import org.apache.kafka.connect.runtime.distributed.Crypto;
  import org.apache.kafka.connect.runtime.rest.errors.BadRequestException;
  
  import org.eclipse.jetty.client.Request;
  
  import java.security.InvalidKeyException;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Arrays;
  import java.util.Base64;
  import java.util.Objects;
  
  import javax.crypto.Mac;
  import javax.crypto.SecretKey;
  
  import jakarta.ws.rs.core.HttpHeaders;
  
  public class InternalRequestSignature {
  
      public static final String SIGNATURE_HEADER = "X-Connect-Authorization";
      public static final String SIGNATURE_ALGORITHM_HEADER = "X-Connect-Request-Signature-Algorithm";
  
      private final byte[] requestBody;
      private final Mac mac;
      private final byte[] requestSignature;
  
      /**
       * Add a signature to a request.
       *
       * @param crypto             the cryptography library used to generate {@link Mac} instances, may not be null
       * @param key                the key to sign the request with; may not be null
       * @param requestBody        the body of the request; may not be null
       * @param signatureAlgorithm the algorithm to use to sign the request; may not be null
       * @param request            the request to add the signature to; may not be null
       */
      public static void addToRequest(Crypto crypto, SecretKey key, byte[] requestBody, String signatureAlgorithm, Request request) {
          Mac mac;
          try {
              mac = crypto.mac(signatureAlgorithm);
          }  catch (NoSuchAlgorithmException e) {
              throw new ConnectException(e);
          }
          byte[] requestSignature = sign(mac, key, requestBody);
          request.headers(field -> {
              field.add(InternalRequestSignature.SIGNATURE_HEADER, Base64.getEncoder().encodeToString(requestSignature));
              field.add(InternalRequestSignature.SIGNATURE_ALGORITHM_HEADER, signatureAlgorithm);
          });
      }
  
      /**
       * Extract a signature from a request.
       *
       * @param crypto        the cryptography library used to generate {@link Mac} instances, may not be null
       * @param requestBody   the body of the request; may not be null
       * @param headers       the headers for the request; may be null
       * @return the signature extracted from the request, or null if one or more request signature
       * headers was not present
       */
      public static InternalRequestSignature fromHeaders(Crypto crypto, byte[] requestBody, HttpHeaders headers) {
          if (headers == null) {
              return null;
          }
  
          String signatureAlgorithm = headers.getHeaderString(SIGNATURE_ALGORITHM_HEADER);
          String encodedSignature = headers.getHeaderString(SIGNATURE_HEADER);
          if (signatureAlgorithm == null || encodedSignature == null) {
              return null;
          }
  
          Mac mac;
          try {
              mac = crypto.mac(signatureAlgorithm);
          } catch (NoSuchAlgorithmException e) {
              throw new BadRequestException(e.getMessage());
          }
  
          byte[] decodedSignature;
          try {
              decodedSignature = Base64.getDecoder().decode(encodedSignature);
          } catch (IllegalArgumentException e) {
              throw new BadRequestException(e.getMessage());
          }
  
          return new InternalRequestSignature(
              requestBody,
              mac,
              decodedSignature
          );
      }
  
      // Public for testing
      public InternalRequestSignature(byte[] requestBody, Mac mac, byte[] requestSignature) {
          this.requestBody = requestBody;
          this.mac = mac;
          this.requestSignature = requestSignature;
      }
  
      public String keyAlgorithm() {
          return mac.getAlgorithm();
      }
  
      public boolean isValid(SecretKey key) {
          return MessageDigest.isEqual(sign(mac, key, requestBody), requestSignature);
      }
  
      private static byte[] sign(Mac mac, SecretKey key, byte[] requestBody) {
          try {
              mac.init(key);
          } catch (InvalidKeyException e) {
              throw new ConnectException(e);
          }
          return mac.doFinal(requestBody);
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o)
              return true;
          if (o == null || getClass() != o.getClass())
              return false;
          InternalRequestSignature that = (InternalRequestSignature) o;
          return MessageDigest.isEqual(requestBody, that.requestBody)
              && mac.getAlgorithm().equals(that.mac.getAlgorithm())
              && mac.getMacLength() == that.mac.getMacLength()
              && mac.getProvider().equals(that.mac.getProvider())
              && MessageDigest.isEqual(requestSignature, that.requestSignature);
      }
  
      @Override
      public int hashCode() {
          int result = Objects.hash(mac);
          result = 31 * result + Arrays.hashCode(requestBody);
          result = 31 * result + Arrays.hashCode(requestSignature);
          return result;
      }
  }
  