src/main/java/com/google/devtools/build/lib/runtime/SafeRequestLogging.java

// Copyright 2020 The Bazel Authors. All rights reserved.
//
// 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.google.devtools.build.lib.runtime;

import static java.util.stream.Collectors.joining;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/** Utils for logging safely user commandlines. */
public class SafeRequestLogging {
  private static final Pattern suppressFromLog =
      Pattern.compile(
          "--client_env=([^=]*(?:auth|pass|cookie|token|api_key)[^=]*)=", Pattern.CASE_INSENSITIVE);

  private static final ImmutableSet<String> CREDENTIAL_OPTION_NAMES =
      ImmutableSet.of(
          "--bes_header",
          "--remote_header",
          "--remote_cache_header",
          "--remote_exec_header",
          "--remote_downloader_header",
          "--tls_client_key",
          "--google_credentials");

  private static final Pattern CREDENTIAL_OPTIONS =
      Pattern.compile(
          "--("
              + CREDENTIAL_OPTION_NAMES.stream().map(s -> s.substring(2)).collect(joining("|"))
              + ")=",
          Pattern.CASE_INSENSITIVE);

  public static ImmutableList<String> redactArguments(List<String> args) {
    ImmutableList.Builder<String> redactedArgs = ImmutableList.builder();
    Matcher credMatcher = CREDENTIAL_OPTIONS.matcher("");
    boolean redactNext = false;
    for (String arg : args) {
      if (redactNext) {
        redactedArgs.add("<REDACTED>");
        redactNext = false;
        continue;
      }
      credMatcher.reset(arg);
      if (credMatcher.lookingAt()) {
        redactedArgs.add(credMatcher.group() + "<REDACTED>");
      } else if (CREDENTIAL_OPTION_NAMES.contains(arg)) {
        redactedArgs.add(arg);
        redactNext = true;
      } else {
        redactedArgs.add(arg);
      }
    }
    return redactedArgs.build();
  }

  private SafeRequestLogging() {}

  /**
   * Generates a string form of a request to be written to the logs, filtering the user environment
   * to remove anything that looks private. The current filter criteria removes any variable whose
   * name includes "auth", "pass", "cookie" or "token".
   *
   * @return the filtered request to write to the log.
   */
  public static String getRequestLogString(List<String> requestStrings) {
    StringBuilder buf = new StringBuilder();
    buf.append('[');
    String sep = "";
    Matcher m = suppressFromLog.matcher("");
    for (String s : requestStrings) {
      buf.append(sep);
      m.reset(s);
      if (m.lookingAt()) {
        buf.append(m.group());
        buf.append("__private_value_removed__");
      } else {
        buf.append(s);
      }
      sep = ", ";
    }
    buf.append(']');
    return buf.toString();
  }
}