+/*
+ Given a buffer, extract the size. We assume the buffer contains one of:
+ <int1><int2><mark>
+ <int1>
+
+ where <int1> is the size in native storage order (v1) and <int2>
+ is the size in network order. If <mark> is present then we assume
+ that <int2> is present and we use that after translating from net
+ byte order. If <mark> is not present, we use <int1>. This allows
+ old versions of RMR to continue to work with new versions that now
+ do the right thing with byte ordering.
+
+ If the receiver of a message is a backlevel RMR, and it uses RTS to
+ return a message, it will only update the old size, but when the
+ message is received back at a new RMR application it will appear that
+ the message came from a new instance. Therefore, we must compare
+ the old and new sizes and if they are different we must use the old
+ size assuming that this is the case.
+*/
+static inline uint32_t extract_mlen( unsigned char* buf ) {
+ uint32_t size; // adjusted (if needed) size for return
+ uint32_t osize; // old size
+ uint32_t* blen; // length in the buffer to extract
+
+ blen = (uint32_t *) buf;
+ if( *(buf + sizeof( int ) * 2 ) == TP_SZ_MARKER ) {
+ osize = *blen; // old size
+ size = ntohl( *(blen+1) ); // pick up the second integer
+ if( osize != size ) { // assume back level return to sender
+ size = osize; // MUST use old size
+ }
+ if( DEBUG > 1 ) rmr_vlog( RMR_VL_DEBUG, "extract msg len converted from net order to: %d\n", size );
+ } else {
+ size = *blen; // old sender didn't encode size
+ if( DEBUG > 1 ) rmr_vlog( RMR_VL_DEBUG, "extract msg len no conversion: %d\n", size );
+ }
+
+ return size;
+}
+
Code Review / ric-plt / lib / rmr.git / blobdiff