Fix infinite loop if blockette chain is corrupt

Author: Chad Trabant

ChangeLog

@@ -1,3 +1,7 @@
+2015.070: 2.15
+	- Fix infinite loop if blockette chain is corrupt.  Patch submitted
+	by Elliott Sales de Andrade.
+
 2015.062: 2.14
 	- Fix memory leak when msr_pack() returns after an error. Patch
 	contributed by Larry Baker and Eric Thomas.

libmseed.h

@@ -30,8 +30,8 @@ extern "C" {
 
 #include "lmplatform.h"
 
-#define LIBMSEED_VERSION "2.14"
-#define LIBMSEED_RELEASE "2015.062"
+#define LIBMSEED_VERSION "2.15"
+#define LIBMSEED_RELEASE "2015.070"
 
 #define MINRECLEN   128      /* Minimum Mini-SEED record length, 2^7 bytes */
                              /* Note: the SEED specification minimum is 256 */

parseutils.c

@@ -5,7 +5,7 @@
  * Written by Chad Trabant
  *   IRIS Data Management Center
  *
- * modified: 2014.248
+ * modified: 2015.070
  ***************************************************************************/
 
 #include <stdio.h>
@@ -284,14 +284,14 @@ ms_detect ( const char *record, int recbuflen )
 
           /* Calculate record size in bytes as 2^(blkt_1000->reclen) */
 	  reclen = (unsigned int) 1 << blkt_1000->reclen;
-	  
+          
 	  break;
         }
 
-      /* Saftey check for invalid offset */
-      if ( next_blkt != 0 && next_blkt < blkt_offset )
+      /* Safety check for invalid offset */
+      if ( next_blkt != 0 && ( next_blkt < 4 || (next_blkt - 4) <= blkt_offset ) )
 	{
-	  ms_log (2, "Invalid blockette offset (%d) less than current offset (%d)\n",
+	  ms_log (2, "Invalid blockette offset (%d) less than or equal to current offset (%d)\n",
 		  next_blkt, blkt_offset);
 	  return -1;
 	}