ota_esphome.h

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#pragma once
 
#include "esphome/core/defines.h"
#ifdef USE_OTA
#include "esphome/components/ota/ota_backend_factory.h"
#include "esphome/components/socket/socket.h"
#ifdef USE_OTA_ENCRYPTION
#include "esphome/components/noise/noise_handshake.h"
#endif
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"
#include "esphome/core/preferences.h"
#include "esphome/core/hash_base.h"
 
namespace esphome {
 
class ESPHomeOTAComponent final : public ota::OTAComponent {
 public:
  enum class OTAState : uint8_t {
    IDLE,
    MAGIC_READ,    // Reading magic bytes
    MAGIC_ACK,     // Sending OK and version after magic bytes
    FEATURE_READ,  // Reading feature flags from client
    FEATURE_ACK,   // Sending feature acknowledgment
#ifdef USE_OTA_PASSWORD
    AUTH_SEND,  // Sending authentication request
    AUTH_READ,  // Reading authentication data
#endif          // USE_OTA_PASSWORD
#ifdef USE_OTA_ENCRYPTION
    NOISE_HANDSHAKE,  // Exchanging Noise handshake frames
#endif
    DATA,  // BLOCKING! Processing OTA data (update, etc.)
  };
#ifdef USE_OTA_PASSWORD
  void set_auth_password(const std::string &password) { password_ = password; }
#else
  // Stub so lambdas referencing set_auth_password() produce a clear error instead of
  // a cryptic "no member" diagnostic. Only fires if the stub is actually instantiated.
  template<bool B = false> void set_auth_password(const std::string &) {
    static_assert(B, "set_auth_password() requires the OTA auth path to be compiled. "
                     "Add 'password: \"\"' (empty string) to your 'ota: - platform: esphome' "
                     "config to enable runtime password rotation.");
  }
#endif  // USE_OTA_PASSWORD
 
#ifdef USE_OTA_ENCRYPTION
  void set_noise_psk(const uint8_t *psk) { this->noise_ctx_.set_psk(psk); }
#endif
 
  void set_port(uint16_t port) { this->port_ = port; }
 
  void setup() override;
  void dump_config() override;
  float get_setup_priority() const override;
  void loop() override;
 
  uint16_t get_port() const { return this->port_; }
 
 protected:
  void handle_handshake_();
  void handle_data_();
#ifdef USE_OTA_PASSWORD
  static constexpr size_t SHA256_HEX_SIZE = 64;  // SHA256 hash as hex string (32 bytes * 2)
  bool handle_auth_send_();
  bool handle_auth_read_();
  bool select_auth_type_();
  void cleanup_auth_();
  void log_auth_warning_(const LogString *msg);
#endif  // USE_OTA_PASSWORD
  bool readall_(uint8_t *buf, size_t len);
  bool writeall_(const uint8_t *buf, size_t len);
  inline bool write_byte_(uint8_t byte) { return this->writeall_(&byte, 1); }
 
#ifdef USE_OTA_ENCRYPTION
  // Heap-allocated only while an encrypted OTA session is active.
  struct NoiseSession {
    ~NoiseSession();
    noise::NoiseResponderHandshake handshake;
    NoiseCipherState *send_cipher{nullptr};
    NoiseCipherState *recv_cipher{nullptr};
    uint16_t frame_len{0};  // total frame size once the header is parsed, 0 until then
    uint16_t frame_pos{0};  // bytes read or written so far
    bool writing{false};    // a produced handshake frame is still being flushed
    uint8_t frame_buf[noise::FRAME_HEADER_SIZE + 1 + noise::MAX_HANDSHAKE_SIZE];
  };
  // The api server's live context when it exists, otherwise our own (a build
  // time key, or the saved key loaded in safe mode)
  const noise::NoiseContext &noise_context_() const;
  bool noise_start_session_(uint8_t server_feature_flags);
  bool handle_noise_handshake_();
  bool noise_try_read_frame_();
  size_t noise_frame_payload_len_(const uint8_t *header, size_t min_len, size_t max_len);
  bool noise_try_write_frame_();
  void noise_send_reject_(const LogString *reason);
  ssize_t noise_decrypt_(uint8_t *buf, size_t len);
  ssize_t noise_read_frame_blocking_(uint8_t *buf, size_t min_ciphertext, size_t max_ciphertext);
  bool noise_readall_(uint8_t *buf, size_t len);
  ssize_t noise_read_data_(uint8_t *buf, size_t capacity);
  bool noise_write_byte_(uint8_t byte);
#endif  // USE_OTA_ENCRYPTION
 
  // Data-phase I/O dispatch: through the noise transport when a session is
  // active, straight to the socket otherwise.
  inline bool data_write_byte_(uint8_t byte) {
#ifdef USE_OTA_ENCRYPTION
    if (this->noise_ != nullptr)
      return this->noise_write_byte_(byte);
#endif
    return this->write_byte_(byte);
  }
  // When encrypted, buf must have room for len + noise::MAC_SIZE bytes.
  inline bool data_readall_(uint8_t *buf, size_t len) {
#ifdef USE_OTA_ENCRYPTION
    if (this->noise_ != nullptr)
      return this->noise_readall_(buf, len);
#endif
    return this->readall_(buf, len);
  }
 
  bool try_read_(size_t to_read, const LogString *desc);
  bool try_write_(size_t to_write, const LogString *desc);
 
  inline bool would_block_(int error_code) const { return error_code == EAGAIN || error_code == EWOULDBLOCK; }
  bool handle_read_error_(ssize_t read, const LogString *desc);
  bool handle_write_error_(ssize_t written, const LogString *desc);
  inline void transition_ota_state_(OTAState next_state) {
    this->ota_state_ = next_state;
    this->handshake_buf_pos_ = 0;  // Reset buffer position for next state
  }
 
  void server_failed_(const LogString *msg);
  void log_socket_error_(const LogString *msg);
  void log_read_error_(const LogString *what);
  void log_start_(const LogString *phase);
  void log_remote_closed_(const LogString *during);
  void cleanup_connection_();
  inline void send_error_and_cleanup_(ota::OTAResponseTypes error) {
    uint8_t error_byte = static_cast<uint8_t>(error);
    this->client_->write(&error_byte, 1);  // Best effort, non-blocking
    this->cleanup_connection_();
  }
  void yield_and_feed_watchdog_();
 
#ifdef USE_OTA_PASSWORD
  std::string password_;
  RAMUniquePtr<uint8_t[]> auth_buf_;
#endif  // USE_OTA_PASSWORD
#ifdef USE_OTA_ENCRYPTION
  noise::NoiseContext noise_ctx_;
#ifdef USE_OTA_ENCRYPTION_PROVISIONED
  // Backs noise_ctx_ in safe mode, where no api server holds the saved key
  RAMUniquePtr<noise::psk_t> saved_psk_;
#endif
  RAMUniquePtr<NoiseSession> noise_;
#endif  // USE_OTA_ENCRYPTION
 
  socket::ListenSocket *server_{nullptr};
  std::unique_ptr<socket::Socket> client_;
  ota::OTABackendPtr backend_;
 
  uint32_t client_connect_time_{0};
  static constexpr size_t HANDSHAKE_BUF_SIZE = 5;
  // Buffer size for OTA data transfer. The upload client derives its maximum
  // encrypted frame plaintext from this (espota2.NOISE_MAX_PLAINTEXT is this
  // minus the 16-byte MAC); both must change together.
  static constexpr size_t OTA_BUFFER_SIZE = 1040;
#ifdef USE_OTA_ENCRYPTION
  // espota2.NOISE_MAX_PLAINTEXT; shrinking the buffer would reject every
  // frame a current CLI sends
  static constexpr size_t NOISE_CLIENT_MAX_PLAINTEXT = 1024;
  static_assert(OTA_BUFFER_SIZE >= NOISE_CLIENT_MAX_PLAINTEXT + noise::MAC_SIZE,
                "OTA_BUFFER_SIZE must fit a full encrypted data frame");
#endif
  static constexpr uint8_t MAGIC_BYTES[5] = {0x6C, 0x26, 0xF7, 0x5C, 0x45};
  // Derived from the feature byte; storing it would pad the trailing bytes
  bool extended_proto_() const;
#ifdef USE_OTA_PARTITIONS
  uint32_t running_app_offset_{0};
  size_t running_app_size_{0};
#endif
  uint16_t port_;
  uint8_t handshake_buf_[HANDSHAKE_BUF_SIZE];
  OTAState ota_state_{OTAState::IDLE};
  uint8_t handshake_buf_pos_{0};
  uint8_t ota_features_{0};
#ifdef USE_OTA_PASSWORD
  uint8_t auth_buf_pos_{0};
  uint8_t auth_type_{0};  // Store auth type to know which hasher to use
#endif                    // USE_OTA_PASSWORD
};
 
}  // namespace esphome
#endif