wireguard.cpp

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#include "wireguard.h"
#ifdef USE_WIREGUARD
#include <cinttypes>
#include <ctime>
 
#include "esphome/core/application.h"
#include "esphome/core/log.h"
#include "esphome/core/time.h"
#include "esphome/components/network/util.h"
#include "esphome/core/helpers.h"
 
#include <esp_wireguard.h>
#include <esp_wireguard_err.h>
 
namespace esphome::wireguard {
 
ESPHOME_LOG_TAG(TAG, "wireguard");
 
/*
 * Cannot use `static const char*` for LOGMSG_PEER_STATUS on esp8266 platform
 * because log messages in `Wireguard::update()` method fail.
 */
#define LOGMSG_PEER_STATUS "Remote peer is %s (latest handshake %s)"
 
static const char *const LOGMSG_ONLINE = "online";
static const char *const LOGMSG_OFFLINE = "offline";
 
void Wireguard::setup() {
  this->wg_config_.address = this->address_;
  this->wg_config_.private_key = this->private_key_;
  this->wg_config_.endpoint = this->peer_endpoint_;
  this->wg_config_.public_key = this->peer_public_key_;
  this->wg_config_.port = this->peer_port_;
  this->wg_config_.netmask = this->netmask_;
  this->wg_config_.persistent_keepalive = this->keepalive_;
 
  if (this->preshared_key_ != nullptr)
    this->wg_config_.preshared_key = this->preshared_key_;
 
  this->publish_enabled_state();
 
  {
    LwIPLock lock;
    this->wg_initialized_ = esp_wireguard_init(&(this->wg_config_), &(this->wg_ctx_));
  }
 
  if (this->wg_initialized_ == ESP_OK) {
    ESP_LOGI(TAG, "Initialized");
    this->wg_peer_offline_time_ = millis();
    this->srctime_->add_on_time_sync_callback([this]() { this->start_connection_(); });
    this->defer([this]() { this->start_connection_(); });  // defer to avoid blocking setup
 
#ifdef USE_TEXT_SENSOR
    if (this->address_sensor_ != nullptr) {
      this->address_sensor_->publish_state(this->address_);
    }
#endif
  } else {
    ESP_LOGE(TAG, "Cannot initialize: error code %d", this->wg_initialized_);
    this->mark_failed();
  }
}
 
void Wireguard::loop() {
  if (!this->enabled_) {
    return;
  }
 
  if ((this->wg_initialized_ == ESP_OK) && (this->wg_connected_ == ESP_OK) && (!network::is_connected())) {
    ESP_LOGV(TAG, "Local network connection has been lost, stopping");
    this->stop_connection_();
  }
}
 
void Wireguard::update() {
  bool peer_up = this->is_peer_up();
  time_t lhs = this->get_latest_handshake();
  bool lhs_updated = (lhs > this->latest_saved_handshake_);
 
  ESP_LOGV(TAG, "enabled=%d, connected=%d, peer_up=%d, handshake: current=%.0f latest=%.0f updated=%d",
           (int) this->enabled_, (int) (this->wg_connected_ == ESP_OK), (int) peer_up, (double) lhs,
           (double) this->latest_saved_handshake_, (int) lhs_updated);
 
  if (lhs_updated) {
    this->latest_saved_handshake_ = lhs;
  }
 
  std::string latest_handshake =
      (this->latest_saved_handshake_ > 0)
          ? ESPTime::from_epoch_local(this->latest_saved_handshake_).strftime("%Y-%m-%d %H:%M:%S %Z")
          : "timestamp not available";
 
  if (peer_up) {
    if (this->wg_peer_offline_time_ != 0) {
      ESP_LOGI(TAG, LOGMSG_PEER_STATUS, LOGMSG_ONLINE, latest_handshake.c_str());
      this->wg_peer_offline_time_ = 0;
    } else {
      ESP_LOGD(TAG, LOGMSG_PEER_STATUS, LOGMSG_ONLINE, latest_handshake.c_str());
    }
  } else {
    if (this->wg_peer_offline_time_ == 0) {
      ESP_LOGW(TAG, LOGMSG_PEER_STATUS, LOGMSG_OFFLINE, latest_handshake.c_str());
      this->wg_peer_offline_time_ = millis();
      this->wg_reconnect_time_ = this->wg_peer_offline_time_;
    } else if (this->enabled_) {
      ESP_LOGD(TAG, LOGMSG_PEER_STATUS, LOGMSG_OFFLINE, latest_handshake.c_str());
      if (millis() - this->wg_reconnect_time_ >= RECONNECT_INTERVAL_MS) {
        this->wg_reconnect_time_ = millis();
        this->stop_connection_();
      }
      this->start_connection_();
    }
 
    // check reboot timeout every time the peer is down
    if (this->enabled_ && this->reboot_timeout_ > 0) {
      if (millis() - this->wg_peer_offline_time_ > this->reboot_timeout_) {
        ESP_LOGE(TAG, "Remote peer is unreachable; rebooting");
        App.reboot();
      }
    }
  }
 
#ifdef USE_BINARY_SENSOR
  if (this->status_sensor_ != nullptr) {
    this->status_sensor_->publish_state(peer_up);
  }
#endif
 
#ifdef USE_SENSOR
  if (this->handshake_sensor_ != nullptr && lhs_updated) {
    this->handshake_sensor_->publish_state((double) this->latest_saved_handshake_);
  }
#endif
}
 
void Wireguard::dump_config() {
  char private_key_masked[MASK_KEY_BUFFER_SIZE];
  char preshared_key_masked[MASK_KEY_BUFFER_SIZE];
  mask_key_to(private_key_masked, sizeof(private_key_masked), this->private_key_);
  mask_key_to(preshared_key_masked, sizeof(preshared_key_masked), this->preshared_key_);
  // clang-format off
  ESP_LOGCONFIG(
      TAG,
      "WireGuard:\n"
      "  Address: %s\n"
      "  Netmask: %s\n"
      "  Private Key: " LOG_SECRET("%s") "\n"
      "  Peer Endpoint: " LOG_SECRET("%s") "\n"
      "  Peer Port: " LOG_SECRET("%d") "\n"
      "  Peer Public Key: " LOG_SECRET("%s") "\n"
      "  Peer Pre-shared Key: " LOG_SECRET("%s"),
      this->address_, this->netmask_, private_key_masked,
      this->peer_endpoint_, this->peer_port_, this->peer_public_key_,
      (this->preshared_key_ != nullptr ? preshared_key_masked : LOG_STR_LITERAL("NOT IN USE")));
  // clang-format on
  ESP_LOGCONFIG(TAG, "  Peer Allowed IPs:");
  for (const AllowedIP *it = this->allowed_ips_; it != nullptr && it->ip != nullptr; it++) {
    ESP_LOGCONFIG(TAG, "    - %s/%s", it->ip, it->netmask);
  }
  ESP_LOGCONFIG(TAG, "  Peer Persistent Keepalive: %d%s", this->keepalive_,
                (this->keepalive_ > 0 ? LOG_STR_LITERAL("s") : LOG_STR_LITERAL(" (DISABLED)")));
  ESP_LOGCONFIG(TAG, "  Reboot Timeout: %" PRIu32 "%s", (this->reboot_timeout_ / 1000),
                (this->reboot_timeout_ != 0 ? LOG_STR_LITERAL("s") : LOG_STR_LITERAL(" (DISABLED)")));
  // be careful: if proceed_allowed_ is true, require connection is false
  ESP_LOGCONFIG(TAG, "  Require Connection to Proceed: %s",
                (this->proceed_allowed_ ? LOG_STR_LITERAL("NO") : LOG_STR_LITERAL("YES")));
  LOG_UPDATE_INTERVAL(this);
}
 
void Wireguard::on_shutdown() { this->stop_connection_(); }
 
bool Wireguard::can_proceed() { return (this->proceed_allowed_ || this->is_peer_up() || !this->enabled_); }
 
bool Wireguard::is_peer_up() const {
  return (this->wg_initialized_ == ESP_OK) && (this->wg_connected_ == ESP_OK) &&
         (esp_wireguardif_peer_is_up(&(this->wg_ctx_)) == ESP_OK);
}
 
time_t Wireguard::get_latest_handshake() const {
  time_t result;
  if (esp_wireguard_latest_handshake(&(this->wg_ctx_), &result) != ESP_OK) {
    result = 0;
  }
  return result;
}
 
void Wireguard::enable() {
  this->enabled_ = true;
  ESP_LOGI(TAG, "Enabled");
  this->publish_enabled_state();
}
 
void Wireguard::disable() {
  this->enabled_ = false;
  this->defer([this]() { this->stop_connection_(); });  // defer to avoid blocking running loop
  ESP_LOGI(TAG, "Disabled");
  this->publish_enabled_state();
}
 
void Wireguard::publish_enabled_state() {
#ifdef USE_BINARY_SENSOR
  if (this->enabled_sensor_ != nullptr) {
    this->enabled_sensor_->publish_state(this->enabled_);
  }
#endif
}
 
void Wireguard::start_connection_() {
  if (!this->enabled_) {
    ESP_LOGV(TAG, "Disabled, cannot start connection");
    return;
  }
 
  if (this->wg_initialized_ != ESP_OK) {
    ESP_LOGE(TAG, "Cannot start: error code %d", this->wg_initialized_);
    return;
  }
 
  if (!network::is_connected()) {
    ESP_LOGD(TAG, "Waiting for local network connection to be available");
    return;
  }
 
  if (!this->srctime_->now().is_valid()) {
    ESP_LOGD(TAG, "Waiting for system time to be synchronized");
    return;
  }
 
  if (this->wg_connected_ == ESP_OK) {
    ESP_LOGV(TAG, "Connection already started");
    return;
  }
 
  ESP_LOGD(TAG, "Starting connection");
  {
    LwIPLock lock;
    this->wg_connected_ = esp_wireguard_connect(&(this->wg_ctx_));
  }
 
  if (this->wg_connected_ == ESP_OK) {
    ESP_LOGI(TAG, "Connection started");
  } else if (this->wg_connected_ == ESP_ERR_RETRY) {
    ESP_LOGD(TAG, "Waiting for endpoint IP address to be available");
    return;
  } else {
    ESP_LOGW(TAG, "Cannot start connection, error code %d", this->wg_connected_);
    return;
  }
 
  ESP_LOGD(TAG, "Configuring allowed IPs list");
  bool allowed_ips_ok = true;
  for (const AllowedIP *it = this->allowed_ips_; it != nullptr && it->ip != nullptr; it++) {
    allowed_ips_ok &= (esp_wireguard_add_allowed_ip(&(this->wg_ctx_), it->ip, it->netmask) == ESP_OK);
  }
 
  if (allowed_ips_ok) {
    ESP_LOGD(TAG, "Allowed IPs list configured correctly");
  } else {
    ESP_LOGE(TAG, "Cannot configure allowed IPs list, aborting");
    this->stop_connection_();
    this->mark_failed();
  }
}
 
void Wireguard::stop_connection_() {
  if (this->wg_initialized_ == ESP_OK && this->wg_connected_ == ESP_OK) {
    ESP_LOGD(TAG, "Stopping connection");
    {
      LwIPLock lock;
      esp_wireguard_disconnect(&(this->wg_ctx_));
    }
    this->wg_connected_ = ESP_FAIL;
  }
}
 
void mask_key_to(char *buffer, size_t len, const char *key) {
  // Format: "XXXXX[...]=\0" = MASK_KEY_BUFFER_SIZE chars minimum
  if (len < MASK_KEY_BUFFER_SIZE || key == nullptr) {
    if (len > 0)
      buffer[0] = '\0';
    return;
  }
  // Copy first 5 characters of the key
  size_t i = 0;
  for (; i < 5 && key[i] != '\0'; ++i) {
    buffer[i] = key[i];
  }
  // Append "[...]="
  const char *suffix = "[...]=";
  for (size_t j = 0; suffix[j] != '\0' && (i + j) < len - 1; ++j) {
    buffer[i + j] = suffix[j];
  }
  buffer[i + 6] = '\0';
}
 
}  // namespace esphome::wireguard
#endif