Fix privacy enclave keystore password file reading eol issue (#554)

-- Read password from first line instead of reading whole file as bytes
 -- Raise appropriate exceptions if file is empty or only contains eol as first line.

fixes #525

Signed-off-by: Usman Saleem <usman@usmans.info>

enclave/build.gradle

@@ -14,6 +14,7 @@ dependencies {
   testImplementation project(':testutil')
 
   testImplementation 'junit:junit'
+  testImplementation 'org.assertj:assertj-core'
 
   // integration test dependencies.
   integrationTestImplementation project(':testutil')

enclave/src/main/java/org/hyperledger/besu/enclave/EnclaveFactory.java

@@ -18,12 +18,12 @@ import org.hyperledger.besu.util.InvalidConfigurationException;
 
 import java.io.IOException;
 import java.net.URI;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.AccessDeniedException;
-import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 
-import com.google.common.base.Charsets;
+import com.google.common.io.Files;
 import io.vertx.core.Vertx;
 import io.vertx.core.http.HttpClientOptions;
 import io.vertx.core.net.PfxOptions;
@@ -112,8 +112,12 @@ public class EnclaveFactory {
     return new PfxOptions().setPassword(password).setPath(keystoreFile.toString());
   }
 
-  private static String readSecretFromFile(final Path path) throws IOException {
-    final byte[] fileContent = Files.readAllBytes(path);
-    return new String(fileContent, Charsets.UTF_8);
+  static String readSecretFromFile(final Path path) throws IOException {
+    final String password =
+        Files.asCharSource(path.toFile(), StandardCharsets.UTF_8).readFirstLine();
+    if (password == null || password.isEmpty()) {
+      throw new InvalidConfigurationException("Keystore password file is empty: " + path);
+    }
+    return password;
   }
 }

enclave/src/test/java/org/hyperledger/besu/enclave/EnclaveFactoryTest.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright ConsenSys AG.
+ *
+ * Licensed 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.enclave;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+import org.hyperledger.besu.util.InvalidConfigurationException;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+public class EnclaveFactoryTest {
+  @ClassRule public static final TemporaryFolder temporaryFolder = new TemporaryFolder();
+  private static final String EMPTY_FILE_ERROR_MSG = "Keystore password file is empty: %s";
+
+  @Test
+  public void passwordCanBeReadFromFile() throws IOException {
+    final File passwordFile = temporaryFolder.newFile();
+    Files.writeString(passwordFile.toPath(), "test" + System.lineSeparator() + "test2");
+    assertThat(EnclaveFactory.readSecretFromFile(passwordFile.toPath())).isEqualTo("test");
+  }
+
+  @Test
+  public void emptyFileThrowsException() throws IOException {
+    final File passwordFile = temporaryFolder.newFile();
+    assertThatExceptionOfType(InvalidConfigurationException.class)
+        .isThrownBy(() -> EnclaveFactory.readSecretFromFile(passwordFile.toPath()))
+        .withMessage(EMPTY_FILE_ERROR_MSG, passwordFile);
+  }
+
+  @Test
+  public void fileWithOnlyEoLThrowsException() throws IOException {
+    final File passwordFile = temporaryFolder.newFile();
+    Files.writeString(passwordFile.toPath(), System.lineSeparator());
+    assertThatExceptionOfType(InvalidConfigurationException.class)
+        .isThrownBy(() -> EnclaveFactory.readSecretFromFile(passwordFile.toPath()))
+        .withMessage(EMPTY_FILE_ERROR_MSG, passwordFile);
+  }
+}