Add anonymizer tool

components/feedback/anonymizer_tool.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/feedback/anonymizer_tool.h"
+
+#include <base/strings/string_number_conversions.h>
+#include <base/strings/string_util.h>
+#include <base/strings/stringprintf.h>
+
+#include "third_party/re2/re2/re2.h"
+
+using re2::RE2;
+
+namespace feedback {
+
+namespace {
+
+// The |kCustomPatterns| array defines patterns to match and anonymize. Each
+// pattern needs to define three capturing parentheses groups:
+//
+// - a group for the pattern before the identifier to be anonymized;
+// - a group for the identifier to be anonymized;
+// - a group for the pattern after the identifier to be anonymized.
+//
+// Every matched identifier (in the context of the whole pattern) is anonymized
+// by replacing it with an incremental instance identifier. Every different
+// pattern defines a separate instance identifier space. See the unit test for
+// AnonymizerTool::AnonymizeCustomPattern for pattern anonymization examples.
+//
+// Useful regular expression syntax:
+//
+// +? is a non-greedy (lazy) +.
+// \b matches a word boundary.
+// (?i) turns on case insensitivy for the remainder of the regex.
+// (?-s) turns off "dot matches newline" for the remainder of the regex.
+// (?:regex) denotes non-capturing parentheses group.
+const char* kCustomPatterns[] = {
+    "(\\bCell ID: ')([0-9a-fA-F]+)(')",                  // ModemManager
+    "(\\bLocation area code: ')([0-9a-fA-F]+)(')",       // ModemManager
+    "(?i-s)(\\bssid[= ]')(.+)(')",                       // wpa_supplicant
+    "(?-s)(\\bSSID - hexdump\\(len=[0-9]+\\): )(.+)()",  // wpa_supplicant
+    "(?-s)(\\[SSID=)(.+?)(\\])",                         // shill
+};
+
+}  // namespace
+
+AnonymizerTool::AnonymizerTool()
+    : custom_patterns_(arraysize(kCustomPatterns)) {}
+
+AnonymizerTool::~AnonymizerTool() {}
+
+std::string AnonymizerTool::Anonymize(const std::string& input) {
+  std::string anonymized = AnonymizeMACAddresses(input);
+  anonymized = AnonymizeCustomPatterns(anonymized);

[vasilii, 2015/12/17 12:40:36]

Looking at the implementation you should take the string by value and move it
when calling AnonymizeCustomPatterns.

[battre, 2015/12/17 13:24:24]

I don't see that this would save much.

[vasilii, 2015/12/17 13:39:05]

You 100% save one copy of |anonymized|. It can be large.

[battre, 2015/12/17 14:34:55]

Done.

+  return anonymized;
+}
+
+std::string AnonymizerTool::AnonymizeMACAddresses(const std::string& input) {
+  // This regular expression finds the next MAC address. It splits the data into
+  // a section preceding the MAC address, an OUI (Organizationally Unique
+  // Identifier) part and a NIC (Network Interface Controller) specific part.
+
+  RE2::Options options;
+  // set_multiline of pcre is not supported by RE2, yet.
+  options.set_dot_nl(true);  // Dot matches a new line.
+  RE2 mac_re(
+      "(.*?)("
+      "[0-9a-fA-F][0-9a-fA-F]:"
+      "[0-9a-fA-F][0-9a-fA-F]:"
+      "[0-9a-fA-F][0-9a-fA-F]):("
+      "[0-9a-fA-F][0-9a-fA-F]:"
+      "[0-9a-fA-F][0-9a-fA-F]:"
+      "[0-9a-fA-F][0-9a-fA-F])",
+      options);
+
+  std::string result;
+  result.reserve(input.size());
+
+  // Keep consuming, building up a result string as we go.
+  re2::StringPiece text(input);
+  std::string pre_mac, oui, nic;
+  while (re2::RE2::Consume(&text, mac_re, RE2::Arg(&pre_mac), RE2::Arg(&oui),
+                           RE2::Arg(&nic))) {
+    // Look up the MAC address in the hash.
+    oui = base::ToLowerASCII(oui);
+    nic = base::ToLowerASCII(nic);
+    std::string mac = oui + ":" + nic;
+    std::string replacement_mac = mac_addresses_[mac];

[vasilii, 2015/12/17 12:40:37]

I'd use a reference here.

[battre, 2015/12/17 13:24:24]

Are you suggesting to the following?

std::string& replacement_mac = mac_addresses_[mac];
...
replacement_mac = base::StringPrintf(...);
// delete mac_addresses_[mac] = replacement_mac;
?

In this case, I would prefer to keep the current version for readability.

+    if (replacement_mac.empty()) {
+      // If not found, build up a replacement MAC address by generating a new
+      // NIC part.
+      int mac_id = mac_addresses_.size();
+      replacement_mac = base::StringPrintf(
+          "%s:%02x:%02x:%02x", oui.c_str(), (mac_id & 0x00ff0000) >> 16,
+          (mac_id & 0x0000ff00) >> 8, (mac_id & 0x000000ff));
+      mac_addresses_[mac] = replacement_mac;
+    }
+
+    result += pre_mac;
+    result += replacement_mac;
+  }
+
+  return result + text.as_string();

[vasilii, 2015/12/17 12:40:37]

You should make it more effective by using operator+=. Otherwise, you create a
copy of result which can be long.

[battre, 2015/12/17 13:24:24]

I have followed the StringPiece::AppendToString idea you gave below.

Done.

+}
+
+std::string AnonymizerTool::AnonymizeCustomPatterns(const std::string& input) {
+  std::string anonymized = input;
+  for (size_t i = 0; i < arraysize(kCustomPatterns); i++) {
+    anonymized = AnonymizeCustomPattern(anonymized, kCustomPatterns[i],
+                                        &custom_patterns_[i]);
+  }
+  return anonymized;
+}
+
+// static
+std::string AnonymizerTool::AnonymizeCustomPattern(
+    const std::string& input,
+    const std::string& pattern,
+    std::map<std::string, std::string>* identifier_space) {
+  RE2::Options options;
+  // set_multiline of pcre is not supported by RE2, yet.
+  options.set_dot_nl(true);  // Dot matches a new line.
+  RE2 re("(.*?)" + pattern, options);
+  DCHECK_EQ(4, re.NumberOfCapturingGroups());
+
+  std::string result;
+  result.reserve(input.size());
+
+  // Keep consuming, building up a result string as we go.
+  re2::StringPiece text(input);
+  std::string pre_match, pre_matched_id, matched_id, post_matched_id;
+  while (RE2::Consume(&text, re, RE2::Arg(&pre_match),
+                      RE2::Arg(&pre_matched_id), RE2::Arg(&matched_id),
+                      RE2::Arg(&post_matched_id))) {
+    std::string replacement_id = (*identifier_space)[matched_id];

[vasilii, 2015/12/17 12:40:37]

I'd use reference here too.

[battre, 2015/12/17 13:24:23]

see above.

+    if (replacement_id.empty()) {
+      replacement_id = base::IntToString(identifier_space->size());
+      (*identifier_space)[matched_id] = replacement_id;
+    }
+
+    result += pre_match;
+    result += pre_matched_id;
+    result += replacement_id;
+    result += post_matched_id;
+  }
+  result += text.as_string();

[vasilii, 2015/12/17 12:40:37]

Use StringPiece::AppendToString.

[battre, 2015/12/17 13:24:24]

Done.

+  return result;
+}
+
+}  // namespace feedback