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/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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.
*/
#include "wifi_system/hostapd_manager.h"
#include <iomanip>
#include <sstream>
#include <string>
#include <vector>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/parseint.h>
#include <android-base/stringprintf.h>
#include <cutils/properties.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <private/android_filesystem_config.h>
#include "wifi_system/supplicant_manager.h"
using android::base::ParseInt;
using android::base::ReadFileToString;
using android::base::StringPrintf;
using android::base::WriteStringToFile;
using std::string;
using std::vector;
using std::stringstream;
namespace android {
namespace wifi_system {
namespace {
const int kDefaultApChannel = 6;
const char kHostapdServiceName[] = "hostapd";
const char kHostapdConfigFilePath[] = "/data/misc/wifi/hostapd.conf";
string GeneratePsk(const vector<uint8_t>& ssid,
const vector<uint8_t>& passphrase) {
string result;
unsigned char psk[SHA256_DIGEST_LENGTH];
// Use the PKCS#5 PBKDF2 with 4096 iterations
if (PKCS5_PBKDF2_HMAC_SHA1(reinterpret_cast<const char*>(passphrase.data()),
passphrase.size(),
ssid.data(), ssid.size(),
4096, sizeof(psk), psk) != 1) {
LOG(ERROR) << "Cannot generate PSK using PKCS#5 PBKDF2";
return result;
}
stringstream ss;
ss << std::hex;
ss << std::setfill('0');
for (int j = 0; j < SHA256_DIGEST_LENGTH; j++) {
ss << std::setw(2) << static_cast<unsigned int>(psk[j]);
}
result = ss.str();
return result;
}
} // namespace
bool HostapdManager::StartHostapd() {
if (!SupplicantManager::EnsureEntropyFileExists()) {
LOG(WARNING) << "Wi-Fi entropy file was not created";
}
if (property_set("ctl.start", kHostapdServiceName) != 0) {
LOG(ERROR) << "Failed to start SoftAP";
return false;
}
LOG(DEBUG) << "SoftAP started successfully";
return true;
}
bool HostapdManager::StopHostapd() {
LOG(DEBUG) << "Stopping the SoftAP service...";
if (property_set("ctl.stop", kHostapdServiceName) < 0) {
LOG(ERROR) << "Failed to stop hostapd service!";
return false;
}
LOG(DEBUG) << "SoftAP stopped successfully";
return true;
}
bool HostapdManager::WriteHostapdConfig(const string& config) {
if (!WriteStringToFile(config, kHostapdConfigFilePath,
S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP,
AID_WIFI, AID_WIFI)) {
int error = errno;
LOG(ERROR) << "Cannot write hostapd config to \""
<< kHostapdConfigFilePath << "\": " << strerror(error);
struct stat st;
int result = stat(kHostapdConfigFilePath, &st);
if (result == 0) {
LOG(ERROR) << "hostapd config file uid: "<< st.st_uid << ", gid: " << st.st_gid
<< ", mode: " << st.st_mode;
} else {
LOG(ERROR) << "Error calling stat() on hostapd config file: " << strerror(errno);
}
return false;
}
return true;
}
string HostapdManager::CreateHostapdConfig(
const string& interface_name,
const vector<uint8_t> ssid,
bool is_hidden,
int channel,
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;
}
stringstream ss;
ss << std::hex;
ss << std::setfill('0');
for (uint8_t b : ssid) {
ss << std::setw(2) << static_cast<unsigned int>(b);
}
const string ssid_as_string = ss.str();
string encryption_config;
if (encryption_type != EncryptionType::kOpen) {
string psk = GeneratePsk(ssid, passphrase);
if (psk.empty()) {
return result;
}
if (encryption_type == EncryptionType::kWpa) {
encryption_config = StringPrintf("wpa=3\n"
"wpa_pairwise=TKIP CCMP\n"
"wpa_psk=%s\n", psk.c_str());
} else if (encryption_type == EncryptionType::kWpa2) {
encryption_config = StringPrintf("wpa=2\n"
"rsn_pairwise=CCMP\n"
"wpa_psk=%s\n", psk.c_str());
} else {
using encryption_t = std::underlying_type<EncryptionType>::type;
LOG(ERROR) << "Unknown encryption type ("
<< static_cast<encryption_t>(encryption_type)
<< ")";
return result;
}
}
result = StringPrintf(
"interface=%s\n"
"driver=nl80211\n"
"ctrl_interface=/data/misc/wifi/hostapd/ctrl\n"
// ssid2 signals to hostapd that the value is not a literal value
// 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"
"ieee80211n=1\n"
"hw_mode=%c\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',
(is_hidden) ? 1 : 0,
encryption_config.c_str());
return result;
}
} // namespace wifi_system
} // namespace android
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