lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/PrivateKeyDetector.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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.
 */

package com.android.tools.lint.checks;

import com.android.annotations.NonNull;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Context;
import com.android.tools.lint.detector.api.Detector;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.Lint;
import com.android.tools.lint.detector.api.Location;
import com.android.tools.lint.detector.api.OtherFileScanner;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.google.common.base.Charsets;
import com.google.common.io.Files;
import java.io.File;
import java.io.IOException;
import java.util.EnumSet;

/** Looks for packaged private key files. */
public class PrivateKeyDetector extends Detector implements OtherFileScanner {
    /** Packaged private key files */
    public static final Issue ISSUE =
            Issue.create(
                            "PackagedPrivateKey",
                            "Packaged private key",
                            "In general, you should not package private key files inside your app.",
                            Category.SECURITY,
                            8,
                            Severity.FATAL,
                            new Implementation(PrivateKeyDetector.class, Scope.OTHER_SCOPE))
                    .setAndroidSpecific(true);

    /** Constructs a new {@link PrivateKeyDetector} check */
    public PrivateKeyDetector() {}

    private static boolean isPrivateKeyFile(File file) {
        if (!file.isFile()
                || (!Lint.endsWith(file.getPath(), "pem")
                        && !Lint.endsWith(file.getPath(), "key"))) {
            return false;
        }

        try {
            String firstLine = Files.readFirstLine(file, Charsets.US_ASCII);
            return firstLine != null
                    && firstLine.startsWith("---")
                    && firstLine.contains("PRIVATE KEY");
        } catch (IOException ex) {
            // Don't care
        }

        return false;
    }

    // ---- Implements OtherFileScanner ----

    @NonNull
    @Override
    public EnumSet<Scope> getApplicableFiles() {
        return Scope.OTHER_SCOPE;
    }

    @Override
    public void run(@NonNull Context context) {
        if (!context.getProject().getReportIssues()) {
            // If this is a library project not being analyzed, ignore it
            return;
        }

        File file = context.file;
        if (isPrivateKeyFile(file)) {
            String fileName = Lint.getFileNameWithParent(context.getClient(), file);
            String message =
                    String.format(
                            "The `%1$s` file seems to be a private key file. "
                                    + "Please make sure not to embed this in your APK file.",
                            fileName);
            context.report(ISSUE, Location.create(file), message);
        }
    }
}