esphome/esphome/components/api/proto.cpp

#include "proto.h"
#include <cinttypes>
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"

namespace esphome::api {

static const char *const TAG = "api.proto";

#ifdef USE_API_VARINT64
optional<ProtoVarInt> ProtoVarInt::parse_wide_(const uint8_t *buffer, uint32_t len, uint32_t *consumed,
                                               uint32_t result32) {
  uint64_t result64 = result32;
  uint32_t limit = std::min(len, uint32_t(10));
  for (uint32_t i = 4; i < limit; i++) {
    uint8_t val = buffer[i];
    result64 |= uint64_t(val & 0x7F) << (i * 7);
    if ((val & 0x80) == 0) {
      *consumed = i + 1;
      return ProtoVarInt(result64);
    }
  }
  return {};
}
#endif

uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size_t length, uint32_t target_field_id) {
  uint32_t count = 0;
  const uint8_t *ptr = buffer;
  const uint8_t *end = buffer + length;

  while (ptr < end) {
    uint32_t consumed;

    // Parse field header (tag)
    auto res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
    if (!res.has_value()) {
      break;  // Invalid data, stop counting
    }

    uint32_t tag = res->as_uint32();
    uint32_t field_type = tag & WIRE_TYPE_MASK;
    uint32_t field_id = tag >> 3;
    ptr += consumed;

    // Count if this is the target field
    if (field_id == target_field_id) {
      count++;
    }

    // Skip field data based on wire type
    switch (field_type) {
      case WIRE_TYPE_VARINT: {  // VarInt - parse and skip
        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
        if (!res.has_value()) {
          return count;  // Invalid data, return what we have
        }
        ptr += consumed;
        break;
      }
      case WIRE_TYPE_LENGTH_DELIMITED: {  // Length-delimited - parse length and skip data
        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
        if (!res.has_value()) {
          return count;
        }
        uint32_t field_length = res->as_uint32();
        ptr += consumed;
        if (field_length > static_cast<size_t>(end - ptr)) {
          return count;  // Out of bounds
        }
        ptr += field_length;
        break;
      }
      case WIRE_TYPE_FIXED32: {  // 32-bit - skip 4 bytes
        if (end - ptr < 4) {
          return count;
        }
        ptr += 4;
        break;
      }
      default:
        // Unknown wire type, can't continue
        return count;
    }
  }

  return count;
}

void ProtoDecodableMessage::decode(const uint8_t *buffer, size_t length) {
  const uint8_t *ptr = buffer;
  const uint8_t *end = buffer + length;

  while (ptr < end) {
    uint32_t consumed;

    // Parse field header
    auto res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
    if (!res.has_value()) {
      ESP_LOGV(TAG, "Invalid field start at offset %ld", (long) (ptr - buffer));
      return;
    }

    uint32_t tag = res->as_uint32();
    uint32_t field_type = tag & WIRE_TYPE_MASK;
    uint32_t field_id = tag >> 3;
    ptr += consumed;

    switch (field_type) {
      case WIRE_TYPE_VARINT: {  // VarInt
        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
        if (!res.has_value()) {
          ESP_LOGV(TAG, "Invalid VarInt at offset %ld", (long) (ptr - buffer));
          return;
        }
        if (!this->decode_varint(field_id, *res)) {
          ESP_LOGV(TAG, "Cannot decode VarInt field %" PRIu32 " with value %" PRIu32 "!", field_id, res->as_uint32());
        }
        ptr += consumed;
        break;
      }
      case WIRE_TYPE_LENGTH_DELIMITED: {  // Length-delimited
        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
        if (!res.has_value()) {
          ESP_LOGV(TAG, "Invalid Length Delimited at offset %ld", (long) (ptr - buffer));
          return;
        }
        uint32_t field_length = res->as_uint32();
        ptr += consumed;
        if (field_length > static_cast<size_t>(end - ptr)) {
          ESP_LOGV(TAG, "Out-of-bounds Length Delimited at offset %ld", (long) (ptr - buffer));
          return;
        }
        if (!this->decode_length(field_id, ProtoLengthDelimited(ptr, field_length))) {
          ESP_LOGV(TAG, "Cannot decode Length Delimited field %" PRIu32 "!", field_id);
        }
        ptr += field_length;
        break;
      }
      case WIRE_TYPE_FIXED32: {  // 32-bit
        if (end - ptr < 4) {
          ESP_LOGV(TAG, "Out-of-bounds Fixed32-bit at offset %ld", (long) (ptr - buffer));
          return;
        }
        uint32_t val = encode_uint32(ptr[3], ptr[2], ptr[1], ptr[0]);
        if (!this->decode_32bit(field_id, Proto32Bit(val))) {
          ESP_LOGV(TAG, "Cannot decode 32-bit field %" PRIu32 " with value %" PRIu32 "!", field_id, val);
        }
        ptr += 4;
        break;
      }
      default:
        ESP_LOGV(TAG, "Invalid field type %u at offset %ld", field_type, (long) (ptr - buffer));
        return;
    }
  }
}

}  // namespace esphome::api