api_frame_helper_noise.h

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#pragma once
#include "api_frame_helper.h"
#ifdef USE_API
#ifdef USE_API_NOISE
#include "noise/protocol.h"
#include "api_noise_context.h"
 
namespace esphome::api {
 
class APINoiseFrameHelper final : public APIFrameHelper {
 public:
  // Noise header structure:
  // Pos 0: indicator (0x01)
  // Pos 1-2: encrypted payload size (16-bit big-endian)
  // Pos 3-6: encrypted type (16-bit) + data_len (16-bit)
  // Pos 7+: actual payload data
  static constexpr uint8_t HEADER_PADDING = 1 + 2 + 2 + 2;  // indicator + size + type + data_len
 
  APINoiseFrameHelper(std::unique_ptr<socket::Socket> socket, APINoiseContext &ctx)
      : APIFrameHelper(std::move(socket)), ctx_(ctx) {
    frame_header_padding_ = HEADER_PADDING;
  }
  ~APINoiseFrameHelper() override;
  APIError init() override;
#ifdef USE_API_PLAINTEXT
  // Take over a connection whose first bytes were consumed by a plaintext
  // helper on an unprovisioned device (see APIError::PROTOCOL_SWITCH_TO_NOISE).
  // Seeds the already-read header bytes and pumps the handshake state machine
  // until it would block.
  APIError init_from_handoff(const uint8_t *header, uint8_t header_len);
#endif
  APIError loop() override;
  APIError read_packet(ReadPacketBuffer *buffer) override;
  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
  APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 
 protected:
  APIError pump_handshake_();
  APIError state_action_();
  APIError state_action_client_hello_();
  APIError state_action_server_hello_();
  APIError state_action_handshake_();
  APIError state_action_handshake_read_();
  APIError state_action_handshake_write_();
  APIError try_read_frame_();
  APIError write_frame_(const uint8_t *data, uint16_t len);
  APIError encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint8_t message_type,
                                  uint16_t &encrypted_len_out);
  APIError init_handshake_();
  APIError check_handshake_finished_();
  void send_explicit_handshake_reject_(const LogString *reason);
  APIError handle_handshake_frame_error_(APIError aerr);
  APIError handle_noise_error_(int err, const LogString *func_name, APIError api_err);
 
  // Pointers first (4 bytes each)
  NoiseHandshakeState *handshake_{nullptr};
  NoiseCipherState *send_cipher_{nullptr};
  NoiseCipherState *recv_cipher_{nullptr};
 
  // Reference to noise context (4 bytes on 32-bit)
  APINoiseContext &ctx_;
 
  // Buffer for noise handshake prologue (released after handshake)
  APIBuffer prologue_;
 
  // NoiseProtocolId (size depends on implementation)
  NoiseProtocolId nid_;
 
  // Group small types together
  // Fixed-size header buffer for noise protocol:
  // 1 byte for indicator + 2 bytes for message size (16-bit value, not varint)
  // Note: Maximum message size is UINT16_MAX (65535), with a limit of 128 bytes during handshake phase
  uint8_t rx_header_buf_[3];
  uint8_t rx_header_buf_len_ = 0;
  // 4 bytes total, no padding
};
 
}  // namespace esphome::api
#endif  // USE_API_NOISE
#endif  // USE_API