Initialisation

Added the packages and files for the backend server

node_modules/graphql/validation/rules/MaxIntrospectionDepthRule.js

@@ -0,0 +1,90 @@
+'use strict';
+
+Object.defineProperty(exports, '__esModule', {
+  value: true,
+});
+exports.MaxIntrospectionDepthRule = MaxIntrospectionDepthRule;
+
+var _GraphQLError = require('../../error/GraphQLError.js');
+
+var _kinds = require('../../language/kinds.js');
+
+const MAX_LISTS_DEPTH = 3;
+
+function MaxIntrospectionDepthRule(context) {
+  /**
+   * Counts the depth of list fields in "__Type" recursively and
+   * returns `true` if the limit has been reached.
+   */
+  function checkDepth(node, visitedFragments = Object.create(null), depth = 0) {
+    if (node.kind === _kinds.Kind.FRAGMENT_SPREAD) {
+      const fragmentName = node.name.value;
+
+      if (visitedFragments[fragmentName] === true) {
+        // Fragment cycles are handled by `NoFragmentCyclesRule`.
+        return false;
+      }
+
+      const fragment = context.getFragment(fragmentName);
+
+      if (!fragment) {
+        // Missing fragments checks are handled by `KnownFragmentNamesRule`.
+        return false;
+      } // Rather than following an immutable programming pattern which has
+      // significant memory and garbage collection overhead, we've opted to
+      // take a mutable approach for efficiency's sake. Importantly visiting a
+      // fragment twice is fine, so long as you don't do one visit inside the
+      // other.
+
+      try {
+        visitedFragments[fragmentName] = true;
+        return checkDepth(fragment, visitedFragments, depth);
+      } finally {
+        visitedFragments[fragmentName] = undefined;
+      }
+    }
+
+    if (
+      node.kind === _kinds.Kind.FIELD && // check all introspection lists
+      (node.name.value === 'fields' ||
+        node.name.value === 'interfaces' ||
+        node.name.value === 'possibleTypes' ||
+        node.name.value === 'inputFields')
+    ) {
+      // eslint-disable-next-line no-param-reassign
+      depth++;
+
+      if (depth >= MAX_LISTS_DEPTH) {
+        return true;
+      }
+    } // handles fields and inline fragments
+
+    if ('selectionSet' in node && node.selectionSet) {
+      for (const child of node.selectionSet.selections) {
+        if (checkDepth(child, visitedFragments, depth)) {
+          return true;
+        }
+      }
+    }
+
+    return false;
+  }
+
+  return {
+    Field(node) {
+      if (node.name.value === '__schema' || node.name.value === '__type') {
+        if (checkDepth(node)) {
+          context.reportError(
+            new _GraphQLError.GraphQLError(
+              'Maximum introspection depth exceeded',
+              {
+                nodes: [node],
+              },
+            ),
+          );
+          return false;
+        }
+      }
+    },
+  };
+}