this.currentHash = newHash.clone();
                }
            }
        }

        public boolean isValid() {
            return isValid;
        }

        public void invalidate() {
            this.isValid = false;
            // Clear sensitive data
            synchronized (hashLock) {
                Arrays.fill(currentHash, (byte) 0);
            }
        }
    }

        }

        int start = bufferIndex;

        // Read compression count
        int compressionCount = SMBUtil.readInt2(buffer, bufferIndex);
        bufferIndex += 2;

        // Validate compression count
        if (compressionCount < 0 || compressionCount > 16) {
            throw new SMBProtocolDecodingException("Invalid compression count: " + compressionCount);
        }

        // Skip padding

            throw new CIFSException("Failed to encrypt message", e);
        }
    }

    /**
     * Validate encryption parameters to prevent security issues
     *
     * @return true if parameters are valid
     */
    private boolean validateEncryptionParameters() {
        // Validate cipher ID
        if (cipherId != CIPHER_AES_128_CCM && cipherId != CIPHER_AES_128_GCM && cipherId != CIPHER_AES_256_CCM

        // Validate negotiate context count - prevent excessive memory allocation
        if (negotiateContextCount < 0 || negotiateContextCount > 100) {
            throw new SMBProtocolDecodingException("Invalid negotiate context count: " + negotiateContextCount + " (must be 0-100)");
        }

        bufferIndex += 4;

        // Validate sufficient buffer space for server GUID and capabilities

        // Try to get from cache first - O(1) operation
        byte[] buf = bufferQueue.poll();
        if (buf != null) {
            queueSize.decrementAndGet();
            return buf;
        }

        // Validate buffer size to prevent overflow
        int bufferSize = SmbComTransaction.TRANSACTION_BUF_SIZE;
        if (bufferSize < 0 || bufferSize > MAX_BUFFER_SIZE) {

So, you could add additional data to the automatically generated schema.

For example, you could decide to read and validate the request with your own code, without using the automatic features of FastAPI with Pydantic, but you could still want to define the request in the OpenAPI schema.

You could do that with `openapi_extra`:

        "price": 42.0,
        "tax": 3.2
    },
    "user": {
        "username": "dave",
        "full_name": "Dave Grohl"
    },
    "importance": 5
}
```

Again, it will convert the data types, validate, document, etc.

## Multiple body params and query { #multiple-body-params-and-query }

Of course, you can also declare additional query parameters whenever you need, additional to any body parameters.

            if (Smb2LeaseState.hasWriteCaching(oldState) && !Smb2LeaseState.hasWriteCaching(newState)) {
                flushCachedWrites(entry.getPath());
            }

            // Invalidate cached data if losing read cache
            if (Smb2LeaseState.hasReadCaching(oldState) && !Smb2LeaseState.hasReadCaching(newState)) {
                invalidateReadCache(entry.getPath());
            }

# Body - Nested Models { #body-nested-models }

With **FastAPI**, you can define, validate, document, and use arbitrarily deeply nested models (thanks to Pydantic).

## List fields { #list-fields }

You can define an attribute to be a subtype. For example, a Python `list`:

{* ../../docs_src/body_nested_models/tutorial001_py310.py hl[12] *}

This will make `tags` be a list, although it doesn't declare the type of the elements of the list.

///

FastAPI will now:

* **Validate** the data making sure that the max length is 50 characters
* Show a **clear error** for the client when the data is not valid