Android O热点hostapd.conf配置文件生成

Android M之前/data/misc/wifi/hostapd.conf文件是在

system/netd/server/SoftapController.cpp里面生成的

/*
 * Arguments:
 *  argv[2] - wlan interface
 *  argv[3] - SSID
 *  argv[4] - Broadcast/Hidden
 *  argv[5] - Channel
 *  argv[6] - Security
 *  argv[7] - Key
 */
int SoftapController::setSoftap(int argc, char *argv[]) {
    int hidden = 0;
    int channel = AP_CHANNEL_DEFAULT;

    if (argc < 5) {
        ALOGE("Softap set is missing arguments. Please use:");
        ALOGE("softap      ");
        return ResponseCode::CommandSyntaxError;
    }

    if (!strcasecmp(argv[4], "hidden"))
        hidden = 1;

    if (argc >= 5) {
        channel = atoi(argv[5]);
        if (channel <= 0)
            channel = AP_CHANNEL_DEFAULT;
    }

    std::string wbuf(StringPrintf("interface=%s\n"
            "driver=nl80211\n"
            "ctrl_interface=/data/misc/wifi/hostapd\n"
            "ssid=%s\n"
            "channel=%d\n"
            "ieee80211n=1\n"
            "hw_mode=%c\n"
            "ignore_broadcast_ssid=%d\n"
            "wowlan_triggers=any\n",
            argv[2], argv[3], channel, (channel <= 14) ? 'g' : 'a', hidden));

    std::string fbuf;
    if (argc > 7) {
        char psk_str[2*SHA256_DIGEST_LENGTH+1];
        if (!strcmp(argv[6], "wpa-psk")) {
            generatePsk(argv[3], argv[7], psk_str);
            fbuf = StringPrintf("%swpa=3\nwpa_pairwise=TKIP CCMP\nwpa_psk=%s\n", wbuf.c_str(), psk_str);
        } else if (!strcmp(argv[6], "wpa2-psk")) {
            generatePsk(argv[3], argv[7], psk_str);
            fbuf = StringPrintf("%swpa=2\nrsn_pairwise=CCMP\nwpa_psk=%s\n", wbuf.c_str(), psk_str);
        } else if (!strcmp(argv[6], "open")) {
            fbuf = wbuf;
        }
    } else if (argc > 6) {
        if (!strcmp(argv[6], "open")) {
            fbuf = wbuf;
        }
    } else {
        fbuf = wbuf;
    }

    if (!WriteStringToFile(fbuf, HOSTAPD_CONF_FILE, 0660, AID_SYSTEM, AID_WIFI)) {
        ALOGE("Cannot write to \"%s\": %s", HOSTAPD_CONF_FILE, strerror(errno));
        return ResponseCode::OperationFailed;
    }
    return ResponseCode::SoftapStatusResult;
}

Android O（可能是Android N开始）的已经挪到frameworks/opt/net/wifi/libwifi_system/hostapd_manager.cpp

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;
}

具体流程可以参考以下文章

（九十二） Android O WiFi热点 开启流程梳理续