Make endianness-conversion macros less fragile.

util.h

@@ -21,10 +21,10 @@ THE SOFTWARE.
 */
 
 #if defined(i386) || defined(__mc68020__) || defined(__x86_64__)
-#define DO_NTOHS(_d, _s) do { _d = ntohs(*(unsigned short*)(_s)); } while(0)
-#define DO_NTOHL(_d, _s) do { _d = ntohl(*(unsigned*)(_s)); } while(0)
-#define DO_HTONS(_d, _s) do { *(unsigned short*)(_d) = htons(_s); } while(0)
-#define DO_HTONL(_d, _s) do { *(unsigned*)(_d) = htonl(_s); } while(0)
+#define DO_NTOHS(_d, _s) do{ _d = ntohs(*(const unsigned short*)(_s)); }while(0)
+#define DO_NTOHL(_d, _s) do{ _d = ntohl(*(const unsigned*)(_s)); } while(0)
+#define DO_HTONS(_d, _s) do{ *(unsigned short*)(_d) = htons(_s); } while(0)
+#define DO_HTONL(_d, _s) do{ *(unsigned*)(_d) = htonl(_s); } while(0)
 /* Some versions of gcc seem to be buggy, and ignore the packed attribute.
    Disable this code until the issue is clarified. */
 /* #elif defined __GNUC__*/