GraphQL Armor Max-Depth Plugin Bypass via Introspection Query Obfuscation

Summary

### Summary A query depth restriction using the `max-depth` property can be bypassed if `ignoreIntrospection` is enabled (which is the default configuration) by naming your query/fragment `__schema`.

### Details At the start of the `countDepth` function, we have the following check for the `ignoreIntrospection` option:

```typescript if (this.config.ignoreIntrospection && 'name' in node && node.name?.value === '__schema') { return 0; } ```

However, the `node` can be one of: `FieldNode`, `FragmentDefinitionNode`, `InlineFragmentNode`, `OperationDefinitionNode`, `FragmentSpreadNode`.

For example, consider sending the following query:

```graphql query hello { books { title } } ```

This would create an `OperationDefinitionNode` where `node.name.value == 'hello'`

The proper way to handle this is to check explicitly for the `__schema` field, which corresponds to a `FieldNode`.

The fix is

```typescript if ( this.config.ignoreIntrospection && 'name' in node && node.name?.value === '__schema' && node.kind === Kind.FIELD ) { return 0; } ```

This ensures that the node is explicitly a `FieldNode`.

### PoC

Max depth: `6`

```graphql query { books { author { books { author { ...__schema } } } } } fragment __schema on Author { books { title } } ```

### Impact

This issue affects applications using the GraphQL Armor Depth Limit plugin with `ignoreIntrospection` enabled.

### Fix

This is fixed in [PR#823](https://github.com/Escape-Technologies/graphql-armor/pull/823)