[Nearby] Obfuscate text preview for URL and Phone

Obfuscation is needed as the text is shown as a preview on the remote
device before accepting the transfer.

Bug: 1085067
Change-Id: I100d369685c5aec2b7bcb97058df68f6c94c4c6e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2368594
Commit-Queue: Richard Knoll <knollr@chromium.org>
Reviewed-by: Alex Chau <alexchau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800736}

chrome/browser/nearby_sharing/text_attachment.cc

@@ -2,18 +2,89 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <algorithm>
 #include <utility>
 
 #include "base/strings/strcat.h"
 #include "chrome/browser/nearby_sharing/text_attachment.h"
+#include "url/gurl.h"
 
 namespace {
 
-constexpr size_t kMaxPreviewTextLength = 32;
+// Tries to get a valid host name from the |text|. Returns nullopt otherwise.
+base::Optional<std::string> GetHostFromText(const std::string& text) {
+  GURL url(text);
+  if (!url.is_valid() || !url.has_host())
+    return base::nullopt;
+
+  return url.host();
+}
+
+// Masks the given |number| depending on the string length:
+//  - length <= 4: Masks all characters
+//  - 4 < length <= 6 Masks the last 4 characters
+//  - 6 < length <= 10: Skips the first 2 and masks the following 4 characters
+//  - length > 10: Skips the first 2 and last 4 characters. Masks the rest of
+//    the string
+// Note: We're assuming a formatted phone number and won't try to reformat to
+// E164 like on Android as there's no easy way of determining the intended
+// region for the phone number.
+std::string MaskPhoneNumber(const std::string& number) {
+  constexpr int kMinMaskedDigits = 4;
+  constexpr int kMaxLeadingDigits = 2;
+  constexpr int kMaxTailingDigits = 4;
+  constexpr int kLengthWithNoLeadingDigits = kMinMaskedDigits;
+  constexpr int kLengthWithNoTailingDigits =
+      kMinMaskedDigits + kMaxLeadingDigits;
+
+  if (number.empty())
+    return number;
+
+  std::string result = number;
+  bool has_plus = false;
+  if (number[0] == '+') {
+    result = number.substr(1);
+    has_plus = true;
+  }
+
+  // First calculate how many digits we would mask having exactly
+  // kMinMaskedDigits digits masked.
+  int leading_digits = 0;
+  if (result.length() > kLengthWithNoLeadingDigits)
+    leading_digits = result.length() - kLengthWithNoLeadingDigits;
+
+  int tailing_digits = 0;
+  if (result.length() > kLengthWithNoTailingDigits)
+    tailing_digits = result.length() - kLengthWithNoTailingDigits;
+
+  // Now limit resulting numbers of digits to maximally allowed values.
+  leading_digits = std::min(kMaxLeadingDigits, leading_digits);
+  tailing_digits = std::min(kMaxTailingDigits, tailing_digits);
+  int masked_digits = result.length() - leading_digits - tailing_digits;
+
+  return base::StrCat({(has_plus ? "+" : ""), result.substr(0, leading_digits),
+                       std::string(masked_digits, 'x'),
+                       result.substr(result.length() - tailing_digits)});
+}
 
 std::string GetTextTitle(const std::string& text_body,
                          TextAttachment::Type type) {
-  // TODO(crbug.com/1085067): Improve title based on |type|.
+  constexpr size_t kMaxPreviewTextLength = 32;
+
+  switch (type) {
+    case TextAttachment::Type::kUrl: {
+      base::Optional<std::string> host = GetHostFromText(text_body);
+      if (host)
+        return *host;
+
+      break;
+    }
+    case TextAttachment::Type::kPhoneNumber:
+      return MaskPhoneNumber(text_body);
+    default:
+      break;
+  }
+
   if (text_body.size() > kMaxPreviewTextLength)
     return base::StrCat({text_body.substr(0, kMaxPreviewTextLength), "…"});
 

chrome/browser/nearby_sharing/text_attachment_unittest.cc

+// Copyright 2020 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 "chrome/browser/nearby_sharing/text_attachment.h"
+
+#include <string>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+struct TextAttachmentTextTitleTestData {
+  TextAttachment::Type type;
+  std::string text_body;
+  std::string expected_text_title;
+} kTextAttachmentTextTitleTestData[] = {
+    {TextAttachment::Type::kText, "Short text", "Short text"},
+    {TextAttachment::Type::kText, "Long text that should be truncated",
+     "Long text that should be truncat…"},
+    {TextAttachment::Type::kUrl,
+     "https://www.google.com/maps/search/restaurants/@/"
+     "data=!3m1!4b1?disco_ad=1234",
+     "www.google.com"},
+    {TextAttachment::Type::kUrl, "Invalid URL", "Invalid URL"},
+    {TextAttachment::Type::kPhoneNumber, "1234", "xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "+1234", "+xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "123456", "12xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "12345678", "12xxxx78"},
+    {TextAttachment::Type::kPhoneNumber, "+447123456789", "+44xxxxxx6789"},
+    {TextAttachment::Type::kPhoneNumber,
+     "+1255555555555555555555555555555555555555555555555556789",
+     "+12xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx6789"},
+    {TextAttachment::Type::kPhoneNumber, "+16196784004", "+16xxxxx4004"},
+    {TextAttachment::Type::kPhoneNumber, "+3841235782564", "+38xxxxxxx2564"},
+    {TextAttachment::Type::kPhoneNumber, "+12345678901", "+12xxxxx8901"},
+    {TextAttachment::Type::kPhoneNumber, "+1234567891", "+12xxxx7891"},
+    {TextAttachment::Type::kPhoneNumber, "+123456789", "+12xxxx789"},
+    {TextAttachment::Type::kPhoneNumber, "+12345678", "+12xxxx78"},
+    {TextAttachment::Type::kPhoneNumber, "+1234567", "+12xxxx7"},
+    {TextAttachment::Type::kPhoneNumber, "+123456", "+12xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "+12345", "+1xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "+1234", "+xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "+123", "+xxx"},
+    {TextAttachment::Type::kPhoneNumber, "+12", "+xx"},
+    {TextAttachment::Type::kPhoneNumber, "+1", "+x"},
+    {TextAttachment::Type::kPhoneNumber,
+     "1255555555555555555555555555555555555555555555555556789",
+     "12xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx6789"},
+    {TextAttachment::Type::kPhoneNumber, "12345678901", "12xxxxx8901"},
+    {TextAttachment::Type::kPhoneNumber, "1234567891", "12xxxx7891"},
+    {TextAttachment::Type::kPhoneNumber, "123456789", "12xxxx789"},
+    {TextAttachment::Type::kPhoneNumber, "12345678", "12xxxx78"},
+    {TextAttachment::Type::kPhoneNumber, "1234567", "12xxxx7"},
+    {TextAttachment::Type::kPhoneNumber, "123456", "12xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "12345", "1xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "1234", "xxxx"},
+    {TextAttachment::Type::kPhoneNumber, "123", "xxx"},
+    {TextAttachment::Type::kPhoneNumber, "12", "xx"},
+    {TextAttachment::Type::kPhoneNumber, "1", "x"},
+    {TextAttachment::Type::kPhoneNumber, "+", "+"},
+};
+
+using TextAttachmentTextTitleTest =
+    testing::TestWithParam<TextAttachmentTextTitleTestData>;
+
+}  // namespace
+
+TEST_P(TextAttachmentTextTitleTest, TextTitleMatches) {
+  TextAttachment attachment(GetParam().type, GetParam().text_body);
+  EXPECT_EQ(GetParam().expected_text_title, attachment.text_title());
+}
+
+INSTANTIATE_TEST_CASE_P(TextAttachmentTextTitleTest,
+                        TextAttachmentTextTitleTest,
+                        testing::ValuesIn(kTextAttachmentTextTitleTestData));

chrome/test/BUILD.gn

@@ -3776,6 +3776,7 @@ test("unit_tests") {
       "../browser/nearby_sharing/nearby_sharing_service_impl_unittest.cc",
       "../browser/nearby_sharing/paired_key_verification_runner_unittest.cc",
       "../browser/nearby_sharing/payload_tracker_unittest.cc",
+      "../browser/nearby_sharing/text_attachment_unittest.cc",
       "../browser/nearby_sharing/webrtc_signaling_messenger_unittest.cc",
       "../browser/password_manager/generated_password_leak_detection_pref_unittest.cc",
       "../browser/performance_manager/test_support/page_discarding_utils.cc",