The DRM DCP CRC-16 is the same as the X.25 CRC-16.

So just use crc16_x25_ccitt_tvb(), which goes a byte at a time rather
than a bit at a time, and which takes a tvbuff rather than requiring you
to call tvb_get_ptr().

It also doesn't 1's-complement the result, so we can compare it against the
0x1D0F in ETSI TS 102 821 V1.4.1 (2012-10) rather than against a
1's-complement version, 0xE2F0.

Change-Id: Ia513f851f0a8ff1e7853278ddf3618c532fb2aba
Reviewed-on: https://code.wireshark.org/review/3507
Reviewed-by: Guy Harris <guy@alum.mit.edu>

5 files changed, 7 insertions, 95 deletions

diff --git a/epan/dissectors/packet-dcp-etsi.c b/epan/dissectors/packet-dcp-etsi.c
index 2b30b1c8f4..9a41e96db3 100644
--- a/epan/dissectors/packet-dcp-etsi.c
+++ b/epan/dissectors/packet-dcp-etsi.c
@@ -28,7 +28,7 @@
 
 #include <epan/packet.h>
 #include <epan/reassemble.h>
-#include <wsutil/crcdrm.h>
+#include <epan/crc16-tvb.h>
 #include <epan/reedsolomon.h>
 #include <epan/wmem/wmem.h>
 #include <string.h>
@@ -494,11 +494,10 @@ dissect_pft(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)
   if (tree) {
     proto_item *ci = NULL;
     guint header_len = offset+2;
-    const char *crc_buf = (const char *) tvb_get_ptr(tvb, 0, header_len);
-    unsigned long c = crc_drm(crc_buf, header_len, 16, 0x11021, 1);
+    guint16 c = crc16_x25_ccitt_tvb(tvb, header_len);
     ci = proto_tree_add_item (pft_tree, hf_edcp_hcrc, tvb, offset, 2, ENC_BIG_ENDIAN);
-    proto_item_append_text(ci, " (%s)", (c==0xe2f0)?"Ok":"bad");
-    proto_tree_add_boolean(pft_tree, hf_edcp_hcrc_ok, tvb, offset, 2, c==0xe2f0);
+    proto_item_append_text(ci, " (%s)", (c==0x1D0F)?"Ok":"bad");
+    proto_tree_add_boolean(pft_tree, hf_edcp_hcrc_ok, tvb, offset, 2, c==0x1D0F);
   }
   offset += 2;
   if (fcount > 1) {             /* fragmented*/
@@ -580,10 +579,9 @@ dissect_af (tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)
   ci = proto_tree_add_item (af_tree, hf_edcp_crc, tvb, offset, 2, ENC_BIG_ENDIAN);
   if (ver & 0x80) { /* crc valid */
     guint len = offset+2;
-    const char *crc_buf = (const char *) tvb_get_ptr(tvb, 0, len);
-    unsigned long c = crc_drm(crc_buf, len, 16, 0x11021, 1);
-    proto_item_append_text(ci, " (%s)", (c==0xe2f0)?"Ok":"bad");
-    proto_tree_add_boolean(af_tree, hf_edcp_crc_ok, tvb, offset, 2, c==0xe2f0);
+    guint16 c = crc16_x25_ccitt_tvb(tvb, len);
+    proto_item_append_text(ci, " (%s)", (c==0x1D0F)?"Ok":"bad");
+    proto_tree_add_boolean(af_tree, hf_edcp_crc_ok, tvb, offset, 2, c==0x1D0F);
   }
   /*offset += 2;*/
 
diff --git a/wsutil/CMakeLists.txt b/wsutil/CMakeLists.txt
index 9efb7b26a4..0a3c1a969a 100644
--- a/wsutil/CMakeLists.txt
+++ b/wsutil/CMakeLists.txt
@@ -60,7 +60,6 @@ set(WSUTIL_FILES
 	crc7.c
 	crc8.c
 	crc11.c
-	crcdrm.c
 	des.c
 	eax.c
 	filesystem.c
diff --git a/wsutil/Makefile.common b/wsutil/Makefile.common
index 95736cd1f8..cb595977c1 100644
--- a/wsutil/Makefile.common
+++ b/wsutil/Makefile.common
@@ -48,7 +48,6 @@ LIBWSUTIL_SRC = 	\
 	crc16.c		\
 	crc16-plain.c	\
 	crc32.c		\
-	crcdrm.c	\
 	des.c		\
 	eax.c		\
 	filesystem.c	\
@@ -101,7 +100,6 @@ libwsutil_nonrepl_INCLUDES = \
 	crc16.h		\
 	crc16-plain.h	\
 	crc32.h		\
-	crcdrm.h	\
 	des.h		\
 	eax.h		\
 	filesystem.h	\
diff --git a/wsutil/crcdrm.c b/wsutil/crcdrm.c
deleted file mode 100644
index cd0e560384..0000000000
--- a/wsutil/crcdrm.c
+++ /dev/null
@@ -1,49 +0,0 @@
-/* crcdrm.c
- * another CRC 16
- * Copyright 2006, British Broadcasting Corporation
- *
- * Wireshark - Network traffic analyzer
- * By Gerald Combs <gerald@wireshark.org>
- * Copyright 1998 Gerald Combs
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#include <stdlib.h>
-
-#include <wsutil/crcdrm.h>
-
-unsigned long crc_drm(const char *data, size_t bytesize,
-	unsigned short num_crc_bits, unsigned long crc_gen, int invert)
-{
-	unsigned long crc_holder, ones, i, msb, databit;
-	signed short j;
-
-	ones = (1 << num_crc_bits) - 1;
-	crc_holder = ones;
-	for (i=0; i<bytesize; i++)
-		for (j=7; j>=0; j--)
-		{
-			crc_holder <<= 1;
-			msb = crc_holder >> num_crc_bits;
-			databit = (data[i] >> j) & 1;
-			if ((msb ^ databit) != 0)
-				crc_holder = crc_holder ^ crc_gen;
-			crc_holder = crc_holder & ones;
-		}
-	if (invert)
-		crc_holder = crc_holder ^ ones; /* invert checksum */
-	return crc_holder;
-}
diff --git a/wsutil/crcdrm.h b/wsutil/crcdrm.h
deleted file mode 100644
index e08f2f949e..0000000000
--- a/wsutil/crcdrm.h
+++ /dev/null
@@ -1,34 +0,0 @@
-/* crcdrm.h
- * another CRC 16
- * Copyright 2006, British Broadcasting Corporation
- *
- * Wireshark - Network traffic analyzer
- * By Gerald Combs <gerald@wireshark.org>
- * Copyright 1998 Gerald Combs
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
- */
-
-#ifndef __CRCDRM_H__
-#define __CRCDRM_H__
-
-
-#include "ws_symbol_export.h"
-
-WS_DLL_PUBLIC
-unsigned long crc_drm(const char *data, size_t bytesize,
-	unsigned short num_crc_bits, unsigned long crc_gen, int invert);
-
-#endif /* __CRCDRM_H__ */