/**
 * @name XPath injection
 * @description Building an XPath expression from user-controlled sources is vulnerable to insertion of
 *              malicious code by the user.
 * @kind path-problem
 * @problem.severity error
 * @security-severity 9.8
 * @precision high
 * @id go/xml/xpath-injection
 * @tags security
 *       external/cwe/cwe-643
 */

import go
import semmle.go.security.XPathInjection
import XPathInjection::Flow::PathGraph

/** Holds if `node` is either a string or a byte slice */
predicate isStringOrByte(XPathInjection::Flow::PathNode node) {
  exists(Type t | t = node.getNode().getType().getUnderlyingType() |
    t instanceof StringType or t instanceof ByteSliceType
  )
}

from XPathInjection::Flow::PathNode source, XPathInjection::Flow::PathNode sink
where XPathInjection::Flow::flowPath(source, sink) and isStringOrByte(sink)
select sink.getNode(), source, sink, "XPath expression depends on a $@.", source.getNode(),
  "user-provided value"