DEV-31979: Introduce LLReqID, a class to help individual event API listeners

implement the ["reqid"] convention. This convention dictates that a response
LLSD from each such API should contain a ["reqid"] key whose value echoes the
["reqid"] value, if any, in the request LLSD.
Add LLReqID support to LLAresListener's "rewriteURI" service, LLSDMessage,
LLCapabilityListener and LLXMLRPCListener.

1 files changed, 25 insertions, 0 deletions

diff --git a/indra/llcommon/llevents.cpp b/indra/llcommon/llevents.cpp
index 7e3c6964dc..c2fa79a524 100644
--- a/indra/llcommon/llevents.cpp
+++ b/indra/llcommon/llevents.cpp
@@ -39,6 +39,8 @@
 #endif
 // other Linden headers
 #include "stringize.h"
+#include "llerror.h"
+#include "llsdutil.h"
 
 /*****************************************************************************
 *   queue_names: specify LLEventPump names that should be instantiated as
@@ -506,3 +508,26 @@ bool LLListenerOrPumpName::operator()(const LLSD& event) const
     }
     return (*mListener)(event);
 }
+
+void LLReqID::stamp(LLSD& response) const
+{
+    if (! (response.isUndefined() || response.isMap()))
+    {
+        // If 'response' was previously completely empty, it's okay to
+        // turn it into a map. If it was already a map, then it should be
+        // okay to add a key. But if it was anything else (e.g. a scalar),
+        // assigning a ["reqid"] key will DISCARD the previous value,
+        // replacing it with a map. That would be Bad.
+        LL_INFOS("LLReqID") << "stamp(" << mReqid << ") leaving non-map response unmodified: "
+                            << response << LL_ENDL;
+        return;
+    }
+    LLSD oldReqid(response["reqid"]);
+    if (! (oldReqid.isUndefined() || llsd_equals(oldReqid, mReqid)))
+    {
+        LL_INFOS("LLReqID") << "stamp(" << mReqid << ") preserving existing [\"reqid\"] value "
+                            << oldReqid << " in response: " << response << LL_ENDL;
+        return;
+    }
+    response["reqid"] = mReqid;
+}