Enable acs for hotspot channel selection

Bug: 69065316
Test: tests/wifitests/runtests.sh (on walleye)
Test: manual
Test: wifi sanity (http://b/71636949)

Manual test
-----------
- enable wifi hotspot from settings
$ adb logcat -b main hostapd '*:S' -e 'ACS'
01-04 18:03:53.482  3040  3040 I hostapd : ACS: Automatic channel selection started, this may take a bit
01-04 18:03:53.482  3040  3040 I hostapd : ACS: Offloading to driver
01-04 18:03:53.827  3040  3040 I hostapd : nl80211: ACS Results: PCH: 6 SCH: 0 BW: 20 VHT0: 0 VHT1: 0 HW_MODE: 1
01-04 18:03:53.827  3040  3040 I hostapd : wlan0: ACS-COMPLETED freq=2437 channel=6

Change-Id: I66782e5921db9063acc1dc8433b42edda120278e

4 files changed, 47 insertions, 20 deletions

diff --git a/libwifi_system/hostapd_manager.cpp b/libwifi_system/hostapd_manager.cpp
index 8c7de320b..d6f31fed0 100644
--- a/libwifi_system/hostapd_manager.cpp
+++ b/libwifi_system/hostapd_manager.cpp
@@ -45,7 +45,6 @@ namespace android {
 namespace wifi_system {
 namespace {
 
-const int kDefaultApChannel = 6;
 const char kHostapdServiceName[] = "hostapd";
 const char kHostapdConfigFilePath[] = "/data/misc/wifi/hostapd.conf";
 
@@ -126,15 +125,11 @@ string HostapdManager::CreateHostapdConfig(
     const string& interface_name,
     const vector<uint8_t> ssid,
     bool is_hidden,
-    int channel,
+    BandType band,
     EncryptionType encryption_type,
     const vector<uint8_t> passphrase) {
   string result;
 
-  if (channel < 0) {
-    channel = kDefaultApChannel;
-  }
-
   if (ssid.size() > 32) {
     LOG(ERROR) << "SSIDs must be <= 32 bytes long";
     return result;
@@ -171,6 +166,21 @@ string HostapdManager::CreateHostapdConfig(
     }
   }
 
+  // hw_mode will be used to specify band for acs.
+  string hw_mode;
+  if (band == BandType::kBand2G) {
+    hw_mode = "g";
+  } else if (band == BandType::kBand5G) {
+    hw_mode = "a";
+  } else if (band == BandType::kBandAny) {
+    hw_mode = "any";
+  } else {
+      LOG(ERROR) << "Unknown band type ("
+                 << static_cast<int>(band)
+                 << ")";
+      return result;
+  }
+
   result = StringPrintf(
       "interface=%s\n"
       "driver=nl80211\n"
@@ -179,16 +189,17 @@ string HostapdManager::CreateHostapdConfig(
       // for use as a SSID.  In this case, we're giving it a hex string
       // and hostapd needs to expect that.
       "ssid2=%s\n"
-      "channel=%d\n"
+      // channel can be selected automatically at run time.
+      "channel=0\n"
+      "acs_exclude_dfs=1\n"
       "ieee80211n=1\n"
-      "hw_mode=%c\n"
+      "hw_mode=%s\n"
       "ignore_broadcast_ssid=%d\n"
       "wowlan_triggers=any\n"
       "%s",
       interface_name.c_str(),
       ssid_as_string.c_str(),
-      channel,
-      (channel <= 14) ? 'g' : 'a',
+      hw_mode.c_str(),
       (is_hidden) ? 1 : 0,
       encryption_config.c_str());
   return result;
diff --git a/libwifi_system/include/wifi_system/hostapd_manager.h b/libwifi_system/include/wifi_system/hostapd_manager.h
index 485267078..a5e1f12f7 100644
--- a/libwifi_system/include/wifi_system/hostapd_manager.h
+++ b/libwifi_system/include/wifi_system/hostapd_manager.h
@@ -33,6 +33,12 @@ class HostapdManager {
     kWpa2,  // Strongly prefer this if at all possible.
   };
 
+  enum class BandType {
+    kBand2G,
+    kBand5G,
+    kBandAny,
+  };
+
   HostapdManager() = default;
   virtual ~HostapdManager() = default;
 
@@ -48,7 +54,7 @@ class HostapdManager {
   // |interface_name| is a network interface name (e.g. "wlan0").
   // |ssid| is the SSID used by the configurated network.
   // |is_hidden| is true iff hostapd should not broadcast the SSID.
-  // |channel| is the WiFi channel (e.g. 6) or <0 for a default value.
+  // |band| defines the band which we will choose channel from.
   // |encryption_type| defines the encryption of the configured network.
   // |passphrase| is ignored for kOpen networks.
   //
@@ -57,7 +63,7 @@ class HostapdManager {
       const std::string& interface_name,
       const std::vector<uint8_t> ssid,
       bool is_hidden,
-      int channel,
+      BandType band,
       EncryptionType encryption,
       const std::vector<uint8_t> passphrase);
 
diff --git a/libwifi_system/testlib/include/wifi_system_test/mock_hostapd_manager.h b/libwifi_system/testlib/include/wifi_system_test/mock_hostapd_manager.h
index 94ed41b42..3521f9d83 100644
--- a/libwifi_system/testlib/include/wifi_system_test/mock_hostapd_manager.h
+++ b/libwifi_system/testlib/include/wifi_system_test/mock_hostapd_manager.h
@@ -34,7 +34,7 @@ class MockHostapdManager : public HostapdManager {
       const std::string& interface_name,
       const std::vector<uint8_t> ssid,
       bool is_hidden,
-      int channel,
+      BandType band,
       EncryptionType encryption,
       const std::vector<uint8_t> passphrase));
   MOCK_METHOD1(WriteHostapdConfig, bool(const std::string& config_file));
diff --git a/libwifi_system/tests/hostapd_manager_unittest.cpp b/libwifi_system/tests/hostapd_manager_unittest.cpp
index b25dd8ec7..8ef74ff05 100644
--- a/libwifi_system/tests/hostapd_manager_unittest.cpp
+++ b/libwifi_system/tests/hostapd_manager_unittest.cpp
@@ -34,7 +34,7 @@ namespace {
 const char kTestInterfaceName[] = "foobar0";
 const char kTestSsidStr[] = "helloisitme";
 const char kTestPassphraseStr[] = "yourelookingfor";
-const int kTestChannel = 2;
+const HostapdManager::BandType kTestBand = HostapdManager::BandType::kBand2G;
 
 // If you generate your config file with both the test ssid
 // and the test passphrase, you'll get this line in the config.
@@ -49,7 +49,7 @@ class HostapdManagerTest : public ::testing::Test {
         kTestInterfaceName,
         cstr2vector(kTestSsidStr),
         false,  // not hidden
-        kTestChannel,
+        kTestBand,
         encryption_type,
         cstr2vector(kTestPassphraseStr));
   }
@@ -66,7 +66,7 @@ void VerifyCommonConfigs(const string& config) {
   EXPECT_THAT(config, HasSubstr("driver=nl80211\n"));
   EXPECT_THAT(config, HasSubstr("ctrl_interface=/data/misc/wifi/hostapd/ctrl\n"));
   EXPECT_THAT(config, HasSubstr("ssid2=68656c6c6f" "6973" "6974" "6d65\n"));
-  EXPECT_THAT(config, HasSubstr("channel=2\n"));
+  EXPECT_THAT(config, HasSubstr("channel=0\n"));
   EXPECT_THAT(config, HasSubstr("hw_mode=g\n"));
   EXPECT_THAT(config, HasSubstr("wowlan_triggers=any\n"));
   EXPECT_THAT(config, HasSubstr("ignore_broadcast_ssid=0\n"));
@@ -104,23 +104,33 @@ TEST_F(HostapdManagerTest, RespectsHiddenSetting) {
         kTestInterfaceName,
         cstr2vector(kTestSsidStr),
         true,
-        kTestChannel,
+        kTestBand,
         HostapdManager::EncryptionType::kOpen,
         vector<uint8_t>());
   EXPECT_THAT(config, HasSubstr("ignore_broadcast_ssid=1\n"));
   EXPECT_THAT(config, Not(HasSubstr("ignore_broadcast_ssid=0\n")));
 }
 
-TEST_F(HostapdManagerTest, CorrectlyInfersHwMode) {
+TEST_F(HostapdManagerTest, CorrectlyInfersHwModeForBand5G) {
   string config = HostapdManager().CreateHostapdConfig(
         kTestInterfaceName,
         cstr2vector(kTestSsidStr),
         true,
-        44,
+        HostapdManager::BandType::kBand5G,
         HostapdManager::EncryptionType::kOpen,
         vector<uint8_t>());
   EXPECT_THAT(config, HasSubstr("hw_mode=a\n"));
-  EXPECT_THAT(config, Not(HasSubstr("hw_mode=g\n")));
+}
+
+TEST_F(HostapdManagerTest, CorrectlyInfersHwModeForBandAny) {
+  string config = HostapdManager().CreateHostapdConfig(
+        kTestInterfaceName,
+        cstr2vector(kTestSsidStr),
+        true,
+        HostapdManager::BandType::kBandAny,
+        HostapdManager::EncryptionType::kOpen,
+        vector<uint8_t>());
+  EXPECT_THAT(config, HasSubstr("hw_mode=any\n"));
 }