JS: Add query for measuring call graph quality

javascript/ql/src/meta/analysis-quality/CallGraphQuality.ql

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+/**
+ * @name Call graph quality
+ * @description Measures the number of resolved and unresolved calls, for diagnostic purposes.
+ * @id js/meta/call-graph-quality
+ */
+
+import javascript::DataFlow
+import semmle.javascript.dataflow.internal.FlowSteps as FlowSteps
+import semmle.javascript.dependencies.Dependencies
+import semmle.javascript.dependencies.FrameworkLibraries
+import semmle.javascript.frameworks.Testing
+
+/** A file we ignore because it is a test file or compiled/generated/bundled code. */
+class IgnoredFile extends File {
+  IgnoredFile() {
+    any(Test t).getFile() = this
+    or
+    getRelativePath().regexpMatch("(?i).*/test(case)?s?/.*")
+    or
+    getBaseName().regexpMatch("(?i)(.*[._\\-]|^)(min|bundle|concat|spec|tests?)\\.[a-zA-Z]+")
+    or
+    exists(TopLevel tl | tl.getFile() = this |
+      tl.isExterns()
+      or
+      tl instanceof FrameworkLibraryInstance
+    )
+  }
+}
+
+/** An call site that is relevant for analysis quality. */
+class RelevantInvoke extends InvokeNode {
+  RelevantInvoke() { not getFile() instanceof IgnoredFile }
+}
+
+/**
+ * Holds if `name` is a the name of an external module.
+ */
+predicate isExternalLibrary(string name) {
+  // Mentioned in package.json
+  any(Dependency dep).info(name, _) or
+  // Node.js built-in
+  name = "assert" or
+  name = "async_hooks" or
+  name = "child_process" or
+  name = "cluster" or
+  name = "crypto" or
+  name = "dns" or
+  name = "domain" or
+  name = "events" or
+  name = "fs" or
+  name = "http" or
+  name = "http2" or
+  name = "https" or
+  name = "inspector" or
+  name = "net" or
+  name = "os" or
+  name = "path" or
+  name = "perf_hooks" or
+  name = "process" or
+  name = "punycode" or
+  name = "querystring" or
+  name = "readline" or
+  name = "repl" or
+  name = "stream" or
+  name = "string_decoder" or
+  name = "timer" or
+  name = "tls" or
+  name = "trace_events" or
+  name = "tty" or
+  name = "dgram" or
+  name = "url" or
+  name = "util" or
+  name = "v8" or
+  name = "vm" or
+  name = "worker_threads" or
+  name = "zlib"
+}
+
+predicate isExternalGlobal(string name) {
+  exists(ExternalGlobalDecl decl |
+    decl.getName() = name
+  )
+  or
+  exists(Dependency dep |
+    // If name is never assigned anywhere, and it coincides with a dependency,
+    // it's most likely coming from there.
+    dep.info(name, _) and
+    not exists(Assignment assign |
+      assign.getLhs().(GlobalVarAccess).getName() = name
+    )
+  )
+  or
+  name = "_"
+}
+
+/**
+ * Gets a node that was derived from an import of `moduleName`.
+ *
+ * This is a rough approximation as it follows all property reads, invocations,
+ * and callbacks, so some of these might refer to internal objects.
+ *
+ * Additionally, we don't recognize when a project imports another file in the
+ * same project using it module name (e.g. import "vscode" from inside the vscode project).
+ */
+SourceNode externalNode() {
+  exists(string moduleName |
+    result = moduleImport(moduleName) and
+    isExternalLibrary(moduleName)
+  )
+  or
+  exists(string name |
+    result = globalVarRef(name) and
+    isExternalGlobal(name)
+  )
+  or
+  result = DOM::domValueRef()
+  or
+  result = jquery()
+  or
+  result = externalNode().getAPropertyRead()
+  or
+  result = externalNode().getAnInvocation()
+  or
+  result = externalNode().(InvokeNode).getCallback(_).getParameter(_)
+}
+
+/**
+ * Gets a data flow node that can be resolved to a callback.
+ *
+ * These are not part of the static call graph, but the data flow analysis can
+ * track them, so we consider them resolved.
+ */
+SourceNode resolvableCallback() {
+  result instanceof FunctionNode
+  or
+  exists(Node arg |
+    FlowSteps::argumentPassing(_, arg, _, result) and
+    resolvableCallback().flowsTo(arg)
+  )
+}
+
+/**
+ * Gets a call site that can be resolved to an function in the same project.
+ */
+RelevantInvoke resolvedCall() {
+  FlowSteps::calls(result, _)
+  or
+  result = resolvableCallback().getAnInvocation()
+}
+
+/**
+ * Gets a call site that is believed to call an external function.
+ */
+RelevantInvoke externalCall() {
+  not result = resolvedCall() and // avoid double counting
+  (
+    // Call to modelled external library
+    result = externalNode()
+    or
+    // 'require' call or similar
+    result = moduleImport(_)
+    or
+    // Resolved to externs file
+    exists(result.(InvokeNode).getACallee(1))
+    or
+    // Modelled as taint step but isn't from an NPM module. E.g. `substring` or `push`.
+    exists(TaintTracking::AdditionalTaintStep step |
+      step.step(_, result)
+      or
+      step.step(result.getAnArgument(), _)
+      or
+      step.step(_, result.getCallback(_).getParameter(_))
+    )
+    or
+    // Commonly used methods that are usually external and not found by the above
+    exists(string name | name = result.(MethodCallNode).getMethodName() |
+      name = "indexOf" or
+      name = "lastIndexOf" or
+      name = "then"
+    )
+  )
+}
+
+/**
+ * Gets a call site that could not be resolved.
+ */
+RelevantInvoke unresolvedCall() {
+  not result = resolvedCall() and
+  not result = externalCall()
+}
+
+// Name all columns in the 'from' clause to get named columns in metadata
+from int resolved, int calls, float ratio
+where
+  calls = count(resolvedCall()) + count(unresolvedCall()) and
+  resolved = count(resolvedCall()) and
+  ratio = resolved / (float)calls
+select resolved, calls, ratio