network_diagnostics: Add util functions to share across routines

Add utility functions that can be shared by routines. This avoids
duplicating code per routine.

TEST=unit_tests --gtest_filter=NetworkDiagnosticsUtilTest*
BUG=chromium:956783

Change-Id: I41cb02956db7b1ee0045c7d7e775ec0a16ee97a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2420913Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Kartik Hegde <khegde@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809113}

chrome/browser/chromeos/BUILD.gn

@@ -1887,6 +1887,8 @@ source_set("chromeos") {
     "net/network_diagnostics/network_diagnostics.h",
     "net/network_diagnostics/network_diagnostics_routine.cc",
     "net/network_diagnostics/network_diagnostics_routine.h",
+    "net/network_diagnostics/network_diagnostics_util.cc",
+    "net/network_diagnostics/network_diagnostics_util.h",
     "net/network_diagnostics/signal_strength_routine.cc",
     "net/network_diagnostics/signal_strength_routine.h",
     "net/network_health/network_health.cc",
@@ -3387,6 +3389,7 @@ source_set("unit_tests") {
     "net/network_diagnostics/lan_connectivity_routine_unittest.cc",
     "net/network_diagnostics/network_diagnostics_routine_unittest.cc",
     "net/network_diagnostics/network_diagnostics_unittest.cc",
+    "net/network_diagnostics/network_diagnostics_util_unittest.cc",
     "net/network_diagnostics/signal_strength_routine_unittest.cc",
     "net/network_health/network_health_unittest.cc",
     "net/network_portal_detector_impl_unittest.cc",

chrome/browser/chromeos/net/network_diagnostics/network_diagnostics_util.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/chromeos/net/network_diagnostics/network_diagnostics_util.h"
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+#include "base/no_destructor.h"
+#include "base/rand_util.h"
+#include "chrome/browser/chromeos/profiles/profile_helper.h"
+#include "chrome/browser/profiles/profile_manager.h"
+#include "components/session_manager/core/session_manager.h"
+#include "content/public/browser/storage_partition.h"
+
+namespace chromeos {
+namespace network_diagnostics {
+
+namespace {
+
+// Returns |num_prefixes| prefixes of size |length|, where no two entries are
+// equal.
+std::vector<std::string> GetRandomPrefixes(size_t num_prefixes, int length) {
+  std::vector<std::string> random_prefixes;
+  while (random_prefixes.size() != num_prefixes) {
+    std::string prefix = GetRandomString(length);
+    // Check that the prefix doesn't already exist.
+    if (std::find(std::begin(random_prefixes), std::end(random_prefixes),
+                  prefix) == std::end(random_prefixes)) {
+      random_prefixes.push_back(prefix);
+    }
+  }
+  return random_prefixes;
+}
+
+}  // namespace
+
+const char* GetGstaticHostSuffix() {
+  static const char* gstatic_host_suffix = "-ccd-testing-v4.metric.gstatic.com";
+  return gstatic_host_suffix;
+}
+
+const std::vector<std::string>& GetFixedHosts() {
+  static base::NoDestructor<std::vector<std::string>> fixed_hostnames(
+      {"www.google.com", "mail.google.com", "drive.google.com",
+       "accounts.google.com", "plus.google.com", "groups.google.com"});
+  return *fixed_hostnames;
+}
+
+std::string GetRandomString(int length) {
+  std::string prefix;
+  for (int i = 0; i < length; i++) {
+    prefix += ('a' + base::RandInt(0, 25));
+  }
+  return prefix;
+}
+
+std::vector<std::string> GetRandomHosts(int num_hosts, int prefix_length) {
+  std::vector<std::string> random_hosts;
+  std::vector<std::string> random_prefixes =
+      GetRandomPrefixes(num_hosts, prefix_length);
+  DCHECK(random_prefixes.size() == num_hosts);
+  for (int i = 0; i < num_hosts; i++) {
+    random_hosts.push_back(random_prefixes[i] + GetGstaticHostSuffix());
+  }
+  return random_hosts;
+}
+
+std::vector<std::string> GetRandomHostsWithFixedHosts(int num_random_hosts,
+                                                      int prefix_length) {
+  std::vector<std::string> hosts = GetFixedHosts();
+  std::vector<std::string> random_hosts =
+      GetRandomHosts(num_random_hosts, prefix_length);
+  hosts.insert(hosts.end(), random_hosts.begin(), random_hosts.end());
+
+  return hosts;
+}
+
+Profile* GetUserProfile() {
+  // Use sign-in profile if user has not logged in
+  if (session_manager::SessionManager::Get()->IsUserSessionBlocked()) {
+    return ProfileHelper::GetSigninProfile();
+  }
+  // Use primary profile if user is logged in
+  return ProfileManager::GetPrimaryUserProfile();
+}
+
+}  // namespace network_diagnostics
+}  // namespace chromeos

chrome/browser/chromeos/net/network_diagnostics/network_diagnostics_util.h

+// 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_NET_NETWORK_DIAGNOSTICS_NETWORK_DIAGNOSTICS_UTIL_H_
+#define CHROME_BROWSER_CHROMEOS_NET_NETWORK_DIAGNOSTICS_NETWORK_DIAGNOSTICS_UTIL_H_
+
+#include <string>
+#include <vector>
+
+class Profile;
+
+namespace chromeos {
+namespace network_diagnostics {
+
+// Returns the Gstatic host suffix. Network diagnostic routines attach a random
+// prefix to |kGstaticHostSuffix| to get a complete hostname.
+const char* GetGstaticHostSuffix();
+
+// Returns the list representing a fixed set of hostnames used by routines.
+const std::vector<std::string>& GetFixedHosts();
+
+// Returns a string of length |length|. Contains characters 'a'-'z', inclusive.
+std::string GetRandomString(int length);
+
+// Returns |num_hosts| random hosts, each suffixed with |kGstaticHostSuffix| and
+// prefixed with a random string of length |prefix_length|.
+std::vector<std::string> GetRandomHosts(int num_hosts, int prefix_length);
+
+// Similar to GetRandomHosts(), but the fixed hosts are prepended to the list.
+// The total number of hosts in this list is GetFixedHosts().size() +
+// num_random_hosts.
+std::vector<std::string> GetRandomHostsWithFixedHosts(int num_random_hosts,
+                                                      int prefix_length);
+
+// Returns the profile associated with this account.
+Profile* GetUserProfile();
+
+}  // namespace network_diagnostics
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_NET_NETWORK_DIAGNOSTICS_NETWORK_DIAGNOSTICS_UTIL_H_

chrome/browser/chromeos/net/network_diagnostics/network_diagnostics_util_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/chromeos/net/network_diagnostics/network_diagnostics_util.h"
+
+#include <string>
+#include <vector>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace chromeos {
+namespace network_diagnostics {
+
+TEST(NetworkDiagnosticsUtilTest, TestGetRandomString) {
+  int length = 8;
+  auto random_string = GetRandomString(length);
+  // Ensure that the length equals |length| and all characters are in between
+  // 'a'-'z', inclusive.
+  ASSERT_EQ(length, random_string.size());
+  for (char const& c : random_string) {
+    ASSERT_TRUE(c >= 'a' && c <= 'z');
+  }
+}
+
+TEST(NetworkDiagnosticsUtilTest, TestGetRandomHosts) {
+  int num_hosts = 10;
+  int prefix_length = 8;
+  std::vector<std::string> random_hosts =
+      GetRandomHosts(num_hosts, prefix_length);
+  // Ensure |random_hosts| has unique entries.
+  std::sort(random_hosts.begin(), random_hosts.end());
+  ASSERT_TRUE(std::adjacent_find(random_hosts.begin(), random_hosts.end()) ==
+              random_hosts.end());
+}
+
+}  // namespace network_diagnostics
+}  // namespace chromeos