C++: rename and add description to hasFlowSource

cpp/ql/src/semmle/code/cpp/models/implementations/Fread.qll

@@ -13,7 +13,8 @@ class Fread extends AliasFunction, RemoteFlowFunction {
 
   override predicate parameterIsAlwaysReturned(int n) { none() }
 
-  override predicate hasFlowSource(FunctionOutput output) {
-    output.isParameterDeref(0)
+  override predicate hasRemoteFlowSource(FunctionOutput output, string description) {
+    output.isParameterDeref(0) and
+    description = "String read by " + this.getName()
   }
 }

cpp/ql/src/semmle/code/cpp/models/implementations/Gets.qll

@@ -44,7 +44,8 @@ class GetsFunction extends DataFlowFunction, TaintFunction, ArrayFunction, Alias
     mustWrite = true
   }
 
-  override predicate hasFlowSource(FunctionOutput output) {
-    output.isParameterDeref(0)
+  override predicate hasRemoteFlowSource(FunctionOutput output, string description) {
+    output.isParameterDeref(0) and
+    description = "String read by " + this.getName()
   }
 }

cpp/ql/src/semmle/code/cpp/models/interfaces/FlowSource.qll

@@ -14,5 +14,8 @@ import semmle.code.cpp.models.Models
  * A library function which returns data read from a network connection.
  */
 abstract class RemoteFlowFunction extends Function {
-  abstract predicate hasFlowSource(FunctionOutput output);
+  /**
+   * Holds if remote data described by `description` flows from `output` of a call to this function.
+   */
+  abstract predicate hasRemoteFlowSource(FunctionOutput output, string description);
 }

cpp/ql/src/semmle/code/cpp/security/FlowSources.qll

@@ -9,26 +9,38 @@ import semmle.code.cpp.models.interfaces.FlowSource
 
 /** A data flow source of remote user input. */
 abstract class RemoteFlowSource extends DataFlow::Node {
+  /** Gets a string that describes the type of this remote flow source. */
+  abstract string getSourceType();
 }
 
 private class TaintedReturnSource extends RemoteFlowSource {
+  string sourceType;
   TaintedReturnSource() {
     exists(RemoteFlowFunction func, CallInstruction instr, FunctionOutput output |
       asInstruction() = instr and
       instr.getStaticCallTarget() = func and
-      func.hasFlowSource(output) and
+      func.hasRemoteFlowSource(output, sourceType) and
       output.isReturnValue()
     )
   }
+
+  override string getSourceType() {
+    result = sourceType
+  }
 }
 
 private class TaintedParameterSource extends RemoteFlowSource {
+  string sourceType;
   TaintedParameterSource() {
     exists(RemoteFlowFunction func, WriteSideEffectInstruction instr, FunctionOutput output |
       asInstruction() = instr and
       instr.getPrimaryInstruction().(CallInstruction).getStaticCallTarget() = func and
-      func.hasFlowSource(output) and
+      func.hasRemoteFlowSource(output, sourceType) and
       output.isParameterDeref(instr.getIndex())
     )
   }
+
+  override string getSourceType() {
+    result = sourceType
+  }
 }