Changeset 79677 in vbox for trunk/src/VBox/Runtime/r3/xml.cpp

Timestamp:

Jul 10, 2019 3:45:05 PM (6 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

131994

Message:

Runtime/r3/xml.cpp: Introduce methods which limit the size of element and attribute values when querying them. Just for sanitizing, not that the buffer size is actually limited.
Main/Appliance+ExtPack: Use size checks to play safe with XML sata.

File:

• trunk/src/VBox/Runtime/r3/xml.cpp (modified) (2 diffs)

trunk/src/VBox/Runtime/r3/xml.cpp

@@ -565 +565 @@
 
 /**
+ * Returns the value of a node. If this node is an attribute, returns
+ * the attribute value; if this node is an element, then this returns
+ * the element text content.
+ * @return
+ * @param   cchValueLimit   If the length of the returned value exceeds this
+ *                          limit a EIPRTFailure exception will be thrown.
+ */
+const char *Node::getValueN(size_t cchValueLimit) const
+{
+    if (   m_pLibAttr
+        && m_pLibAttr->children
+        )
+    {
+        // libxml hides attribute values in another node created as a
+        // single child of the attribute node, and it's in the content field
+        AssertStmt(strlen((const char *)m_pLibAttr->children->content) <= cchValueLimit, throw EIPRTFailure(VERR_BUFFER_OVERFLOW, "Attribute '%s' exceeds limit of %zu bytes", m_pcszName, cchValueLimit));
+        return (const char *)m_pLibAttr->children->content;
+    }
+
+    if (   m_pLibNode
+        && m_pLibNode->children)
+    {
+        AssertStmt(strlen((const char *)m_pLibNode->children->content) <= cchValueLimit, throw EIPRTFailure(VERR_BUFFER_OVERFLOW, "Element '%s' exceeds limit of %zu bytes", m_pcszName, cchValueLimit));
+        return (const char *)m_pLibNode->children->content;
+    }
+
+    return NULL;
+}
+
+/**
  * Copies the value of a node into the given integer variable.
  * Returns TRUE only if a value was found and was actually an
@@ -1152 +1182 @@
             return true;
         }
+    }
+
+    return false;
+}
+
+/**
+ * Convenience method which attempts to find the attribute with the given
+ * name and returns its value as a string.
+ *
+ * @param   pcszMatch       Name of attribute to find.
+ * @param   ppcsz           Where to return the attribute.
+ * @param   cchValueLimit   If the length of the returned value exceeds this
+ *                          limit a EIPRTFailure exception will be thrown.
+ * @param   pcszNamespace   The attribute name space prefix or NULL.
+ * @returns Boolean success indicator.
+ */
+bool ElementNode::getAttributeValueN(const char *pcszMatch, const char **ppcsz, size_t cchValueLimit, const char *pcszNamespace /*= NULL*/) const
+{
+    const AttributeNode *pAttr = findAttribute(pcszMatch, pcszNamespace);
+    if (pAttr)
+    {
+        *ppcsz = pAttr->getValueN(cchValueLimit);
+        return true;
+    }
+    return false;
+}
+
+/**
+ * Convenience method which attempts to find the attribute with the given
+ * name and returns its value as a string.
+ *
+ * @param   pcszMatch       Name of attribute to find.
+ * @param   pStr            Pointer to the string object that should receive the
+ *                          attribute value.
+ * @param   cchValueLimit   If the length of the returned value exceeds this
+ *                          limit a EIPRTFailure exception will be thrown.
+ * @param   pcszNamespace   The attribute name space prefix or NULL.
+ * @returns Boolean success indicator.
+ *
+ * @throws  Whatever the string class may throw on assignment.
+ */
+bool ElementNode::getAttributeValueN(const char *pcszMatch, RTCString *pStr, size_t cchValueLimit, const char *pcszNamespace /*= NULL*/) const
+{
+    const AttributeNode *pAttr = findAttribute(pcszMatch, pcszNamespace);
+    if (pAttr)
+    {
+        *pStr = pAttr->getValueN(cchValueLimit);
+        return true;
+    }
+
+    return false;
+}
+
+/**
+ * Like getAttributeValue (ministring variant), but makes sure that all backslashes
+ * are converted to forward slashes.
+ *
+ * @param   pcszMatch       Name of attribute to find.
+ * @param   pStr            Pointer to the string object that should
+ *                          receive the attribute path value.
+ * @param   cchValueLimit   If the length of the returned value exceeds this
+ *                          limit a EIPRTFailure exception will be thrown.
+ * @param   pcszNamespace   The attribute name space prefix or NULL.
+ * @returns Boolean success indicator.
+ */
+bool ElementNode::getAttributeValuePathN(const char *pcszMatch, RTCString *pStr, size_t cchValueLimit, const char *pcszNamespace /*= NULL*/) const
+{
+    if (getAttributeValueN(pcszMatch, pStr, cchValueLimit, pcszNamespace))
+    {
+        pStr->findReplace('\\', '/');
+        return true;
     }