From b24db0eaa5f5ed7f55cb521f52d03d976673e158 Mon Sep 17 00:00:00 2001
From: xirvik <community@xirvik.net>
Date: Wed, 12 Aug 2026 15:50:56 +0000
Subject: [PATCH] Do not dereference missing text nodes in the tinyxml2
 backend.

Empty elements and element children crashed the parser on a null.
---
 src/rpc/xmlrpc_tinyxml2.cc | 31 ++++++++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/rpc/xmlrpc_tinyxml2.cc b/src/rpc/xmlrpc_tinyxml2.cc
index 7ef6098b..099f6fbd 100644
--- a/src/rpc/xmlrpc_tinyxml2.cc
+++ b/src/rpc/xmlrpc_tinyxml2.cc
@@ -49,13 +49,23 @@ element_access(const tinyxml2::XMLElement* elem, std::initializer_list<std::stri
   return result;
 }
 
+const char*
+element_text_value(const tinyxml2::XMLNode* node) {
+  auto text = node->ToText();
+
+  if (text == nullptr)
+    throw rpc_error(XMLRPC_TYPE_ERROR, "expected a text value");
+
+  return text->Value();
+}
+
 long long
 element_to_int(const tinyxml2::XMLNode* elem) {
   char* pos;
   if (elem->FirstChild() == nullptr) {
     throw rpc_error(XMLRPC_TYPE_ERROR, "unable to parse empty integer");
   }
-  auto str    = elem->FirstChild()->ToText()->Value();
+  auto str    = element_text_value(elem->FirstChild());
   auto result = std::strtoll(str, &pos, 10);
   if (pos == str || *pos != '\0')
     throw rpc_error(XMLRPC_TYPE_ERROR, "unable to parse integer value");
@@ -85,7 +95,7 @@ xml_value_to_object(const tinyxml2::XMLNode* elem) {
     if (child_element == nullptr)
       return torrent::Object("");
 
-    return torrent::Object(child_element->ToText()->Value());
+    return torrent::Object(element_text_value(child_element));
 
   } else if (std::strncmp(root_type, "int", sizeof("int")) == 0 ||
              std::strncmp(root_type, "i4", sizeof("i4")) == 0 ||
@@ -98,7 +108,7 @@ xml_value_to_object(const tinyxml2::XMLNode* elem) {
     if (child_element == nullptr)
       throw rpc_error(XMLRPC_TYPE_ERROR, "empty boolean element");
 
-    auto boolean_text = std::string(child_element->ToText()->Value());
+    auto boolean_text = std::string(element_text_value(child_element));
 
     if (boolean_text == "1")
       return torrent::Object((int64_t)1);
@@ -129,7 +139,12 @@ xml_value_to_object(const tinyxml2::XMLNode* elem) {
       if (name_element == nullptr)
         throw rpc_error(XMLRPC_PARSE_ERROR, "struct member missing name element");
 
-      map[name_element->GetText()] = std::move(xml_value_to_object(child->FirstChildElement("value")));
+      auto name_text = name_element->GetText();
+
+      if (name_text == nullptr)
+        throw rpc_error(XMLRPC_PARSE_ERROR, "struct member has an empty name element");
+
+      map[name_text] = std::move(xml_value_to_object(child->FirstChildElement("value")));
     }
 
     return map_raw;
@@ -140,7 +155,7 @@ xml_value_to_object(const tinyxml2::XMLNode* elem) {
     if (child_element == nullptr)
       return torrent::Object("");
 
-    return torrent::Object(utils::decode_base64(utils::remove_newlines(child_element->ToText()->Value())));
+    return torrent::Object(utils::decode_base64(utils::remove_newlines(element_text_value(child_element))));
 
   } else {
     throw rpc_error(XMLRPC_INTERNAL_ERROR, "received unsupported value type: " + std::string(root_type));
@@ -300,6 +315,9 @@ process_document(const tinyxml2::XMLDocument* doc, tinyxml2::XMLPrinter* printer
   if (doc->FirstChildElement("methodCall")->FirstChildElement("methodName") == nullptr)
     throw rpc_error(XMLRPC_PARSE_ERROR, "methodName element not found");
   auto            method_name = doc->FirstChildElement("methodCall")->FirstChildElement("methodName")->GetText();
+
+  if (method_name == nullptr)
+    throw rpc_error(XMLRPC_PARSE_ERROR, "methodName element is empty");
   torrent::Object result;
 
   // Add a shim here for system.multicall to allow better code reuse, and
@@ -310,6 +328,9 @@ process_document(const tinyxml2::XMLDocument* doc, tinyxml2::XMLPrinter* printer
     auto  parent_elements = element_access(doc->RootElement(), {"params", "param", "value", "array", "data"});
     for (auto child = parent_elements->FirstChildElement("value"); child; child = child->NextSiblingElement("value")) {
       auto sub_method_name = element_access(child, {"struct", "member", "value", "string"})->GetText();
+
+      if (sub_method_name == nullptr)
+        throw rpc_error(XMLRPC_PARSE_ERROR, "multicall methodName element is empty");
       // If sub_params ends up a nullptr at the end of this if-chian,
       // execute_command will turn it into an empty list
       auto sub_params = element_access(child, {"struct", "member"});