Correctly cast the extension lengths (#2144)

Correctly use a 32 bit integer for accumulating the length of ping
extensions.

The current code may accidentally truncate the length of an
extension that is greater than 64kb and fail the validation check. We
don't currently emit any extensions that are this length, but if we were
to do so in the future we might have issues with older nodes (without
this fix) will silently drop packets from newer nodes. We should
backport this to all versions.

Signed-off-by: Madelyn Olson <[email protected]>

Author: madolson

src/cluster_legacy.c

@@ -3197,7 +3197,7 @@ int clusterIsValidPacket(clusterLink *link) {
         if (hdr->mflags[0] & CLUSTERMSG_FLAG0_EXT_DATA) {
             clusterMsgPingExt *ext = getInitialPingExt(hdr, count);
             while (extensions--) {
-                uint16_t extlen = getPingExtLength(ext);
+                uint32_t extlen = getPingExtLength(ext);
                 if (extlen % 8 != 0) {
                     serverLog(LL_WARNING, "Received a %s packet without proper padding (%d bytes)",
                               clusterGetMessageTypeString(type), (int)extlen);