Add CRC verification to Modbus RTU dissector. CRC algorithm is the same as the "crc16-plain" with a different initial CRC (0xFFFF instead of 0). Created crc16_plain_tvb_offset_seed to "replace" crc16_plain_tvb_offset, but didn't remove crc16_plain_tvb_offset for backwards compatibility worries. Updated only dissector that used crc16_plain_tvb_offset (profinet/packet-pn-rt.c) to use crc16_plain_tvb_offset_seed(..., 0)

svn path=/trunk/; revision=45854

1 files changed, 16 insertions, 0 deletions

diff --git a/epan/crc16-tvb.h b/epan/crc16-tvb.h
index 0a49bda326..bad28217e3 100644
--- a/epan/crc16-tvb.h
+++ b/epan/crc16-tvb.h
@@ -86,6 +86,22 @@ extern guint16 crc16_ccitt_tvb_offset_seed(tvbuff_t *tvb, guint offset,
  @return The CRC16 checksum. */
 extern guint16 crc16_plain_tvb_offset(tvbuff_t *tvb, guint offset, guint len);
 
+/** Compute the "plain" CRC16 checksum of a tv buffer using the following
+ * parameters:
+ *    Width        = 16
+ *    Poly         = 0x8005
+ *    XorIn        = 0x0000
+ *    ReflectIn    = True
+ *    XorOut       = 0x0000
+ *    ReflectOut   = True
+ *    Algorithm    = table-driven
+ *    Direct       = True
+ @param tvb The tv buffer containing the data.
+ @param offset The offset into the tv buffer.
+ @param len The number of bytes to include in the computation.
+ @param crc Starting CRC value
+ @return The CRC16 checksum. */
+extern guint16 crc16_plain_tvb_offset_seed(tvbuff_t *tvb, guint offset, guint len, guint16 crc);
 
 #ifdef __cplusplus
 }