Extend MarshalingFunction and UnmarshalingFunction with encoding/asn1

ql/src/semmle/go/frameworks/stdlib/EncodingAsn1.qll

@@ -6,6 +6,34 @@ import go
 
 /** Provides models of commonly used functions in the `encoding/asn1` package. */
 module EncodingAsn1 {
+  /** The `Marshal` or `MarshalWithParams` function in the `encoding/asn1` package. */
+  private class MarshalFunction extends MarshalingFunction::Range {
+    MarshalFunction() {
+      hasQualifiedName("encoding/asn1", "Marshal") or
+      hasQualifiedName("encoding/asn1", "MarshalWithParams")
+    }
+
+    override FunctionInput getAnInput() { result.isParameter(0) }
+
+    override FunctionOutput getOutput() { result.isResult(0) }
+
+    override string getFormat() { result = "ASN1" }
+  }
+
+  /** The `Unmarshal` or `UnmarshalWithParams` function in the `encoding/asn1` package. */
+  private class UnmarshalFunction extends UnmarshalingFunction::Range {
+    UnmarshalFunction() {
+      hasQualifiedName("encoding/asn1", "Unmarshal") or
+      hasQualifiedName("encoding/asn1", "UnmarshalWithParams")
+    }
+
+    override FunctionInput getAnInput() { result.isParameter(0) }
+
+    override FunctionOutput getOutput() { result.isParameter(1) }
+
+    override string getFormat() { result = "ASN1" }
+  }
+
   private class FunctionModels extends TaintTracking::FunctionModel {
     FunctionInput inp;
     FunctionOutput outp;