From Jesper Peterson:

	Extract the FCS decoding section of the PPP_HDLC dissector to
	allow the CHDLC dissector to use the same routine.

	The ppp_options used for preferences has been renamed to
	fcs_options and exported via packet-ppp.h so CHDLC gets a
	separate (but identical) FCS preference.

	This means prefs.h has to be included before packet-ppp.h so a
	couple of ppp related files (packet-{gtp,null,raw,vj}.c) had
	their includes slightly re-arranged.

From me: make the PPP/CHDLC FCS code use "crc32()" to check the 32-bit
FCS.

svn path=/trunk/; revision=8266

1 files changed, 143 insertions, 207 deletions

diff --git a/packet-ppp.c b/packet-ppp.c
index 5913e49510..8e643316b3 100644
--- a/packet-ppp.c
+++ b/packet-ppp.c
@@ -2,7 +2,7 @@
  * Routines for ppp packet disassembly
  * RFC 1661, RFC 1662
  *
- * $Id: packet-ppp.c,v 1.114 2003/07/11 09:30:48 guy Exp $
+ * $Id: packet-ppp.c,v 1.115 2003/08/26 05:52:50 guy Exp $
  *
  * Ethereal - Network traffic analyzer
  * By Gerald Combs <gerald@ethereal.com>
@@ -43,6 +43,7 @@
 #include "packet-ipx.h"
 #include "packet-vines.h"
 #include "nlpid.h"
+#include "crc32.h"
 
 #define ppp_min(a, b)  ((a<b) ? a : b)
 
@@ -168,6 +169,14 @@ static gint ppp_fcs_decode = 0; /* 0 = No FCS, 1 = 16 bit FCS, 2 = 32 bit FCS */
 #define NO_FCS 0
 #define FCS_16 1
 #define FCS_32 2
+
+const enum_val_t fcs_options[] = {
+  {"None", NO_FCS},
+  {"16-Bit", FCS_16},
+  {"32-Bit", FCS_32},
+  {NULL, -1}
+};
+
 gboolean ppp_vj_decomp = TRUE; /* Default to VJ header decompression */
 
 /*
@@ -1323,75 +1332,6 @@ static const ip_tcp_opt ipv6cp_opts[] = {
 
 #define N_IPV6CP_OPTS	(sizeof ipv6cp_opts / sizeof ipv6cp_opts[0])
 
-
-static const unsigned int fcstab_32[256] =
-      {
-      0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
-      0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
-      0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
-      0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
-      0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
-      0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
-      0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
-      0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
-      0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
-      0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
-      0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
-      0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
-      0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
-      0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
-      0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
-      0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
-      0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
-      0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
-      0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
-      0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
-      0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
-      0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
-      0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
-      0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
-      0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
-      0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
-      0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
-      0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
-      0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
-      0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
-      0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
-      0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
-      0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
-      0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
-      0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
-      0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
-      0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
-      0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
-      0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
-      0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
-      0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
-      0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
-      0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
-      0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
-      0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
-      0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
-      0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
-      0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
-      0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
-      0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
-      0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
-      0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
-      0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
-      0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
-      0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
-      0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
-      0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
-      0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
-      0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
-      0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
-      0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
-      0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
-      0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
-      0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
-      };
-
 static const unsigned short fcstab_16[256] = {
         0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
         0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
@@ -1457,21 +1397,145 @@ fcs16(register guint16 fcs, tvbuff_t * tvbuff)
 *******************************************************************************
 */
 static guint32
-fcs32(guint32 fcs, tvbuff_t * tvbuff)
+fcs32(tvbuff_t * tvbuff)
 {
-    int offset = 0;
     guint len = tvb_length(tvbuff)-4;
-    guint8 val;
 
     /* Check for invalid Length */
     if (len == 0)
         return (0x00000000);
+    return crc32(tvb_get_ptr(tvbuff, 0, len), len);
+}
 
-    while (len--) {
-	val = tvb_get_guint8(tvbuff, offset++);
-	fcs = (((fcs) >> 8) ^ fcstab_32[((fcs) ^ (val)) & 0xff]);
+tvbuff_t *
+decode_fcs(tvbuff_t *tvb, proto_tree *fh_tree, int fcs_decode, int proto_offset)
+{
+  tvbuff_t   *next_tvb;
+  gint       len, reported_len;
+  int        rx_fcs_offset;
+  guint32    rx_fcs_exp;
+  guint32    rx_fcs_got;
+
+  /*
+   * Remove the FCS, if any, from the packet data.
+   */
+  switch (fcs_decode) {
+
+  case NO_FCS:
+    next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1);
+    break;
+
+  case FCS_16:
+    /*
+     * Do we have the entire packet, and does it include a 2-byte FCS?
+     */
+    len = tvb_length_remaining(tvb, proto_offset);
+    reported_len = tvb_reported_length_remaining(tvb, proto_offset);
+    if (reported_len < 2 || len < 0) {
+      /*
+       * The packet is claimed not to even have enough data for a 2-byte FCS,
+       * or we're already past the end of the captured data.
+       * Don't slice anything off.
+       */
+      next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1);
+    } else if (len < reported_len) {
+      /*
+       * The packet is claimed to have enough data for a 2-byte FCS, but
+       * we didn't capture all of the packet.
+       * Slice off the 2-byte FCS from the reported length, and trim the
+       * captured length so it's no more than the reported length; that
+       * will slice off what of the FCS, if any, is in the captured
+       * length.
+       */
+      reported_len -= 2;
+      if (len > reported_len)
+        len = reported_len;
+      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
+    } else {
+      /*
+       * We have the entire packet, and it includes a 2-byte FCS.
+       * Slice it off.
+       */
+      len -= 2;
+      reported_len -= 2;
+      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
+
+      /*
+       * Compute the FCS and put it into the tree.
+       */
+      rx_fcs_offset = proto_offset + len;
+      rx_fcs_exp = fcs16(0xFFFF, tvb);
+      rx_fcs_got = tvb_get_letohs(tvb, rx_fcs_offset);
+      if (rx_fcs_got != rx_fcs_exp) {
+        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2,
+                            "FCS 16: 0x%04x (incorrect, should be 0x%04x)",
+                            rx_fcs_got, rx_fcs_exp);
+      } else {
+        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2,
+                            "FCS 16: 0x%04x (correct)",
+                            rx_fcs_got);
+      }
+    }
+    break;
+
+  case FCS_32:
+    /*
+     * Do we have the entire packet, and does it include a 4-byte FCS?
+     */
+    len = tvb_length_remaining(tvb, proto_offset);
+    reported_len = tvb_reported_length_remaining(tvb, proto_offset);
+    if (reported_len < 4) {
+      /*
+       * The packet is claimed not to even have enough data for a 4-byte FCS.
+       * Just pass on the tvbuff as is.
+       */
+      next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1);
+    } else if (len < reported_len) {
+      /*
+       * The packet is claimed to have enough data for a 4-byte FCS, but
+       * we didn't capture all of the packet.
+       * Slice off the 4-byte FCS from the reported length, and trim the
+       * captured length so it's no more than the reported length; that
+       * will slice off what of the FCS, if any, is in the captured
+       * length.
+       */
+      reported_len -= 4;
+      if (len > reported_len)
+        len = reported_len;
+      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
+    } else {
+      /*
+       * We have the entire packet, and it includes a 4-byte FCS.
+       * Slice it off.
+       */
+      len -= 4;
+      reported_len -= 4;
+      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
+
+      /*
+       * Compute the FCS and put it into the tree.
+       */
+      rx_fcs_offset = proto_offset + len;
+      rx_fcs_exp = fcs32(tvb);
+      rx_fcs_got = tvb_get_letohl(tvb, rx_fcs_offset);
+      if (rx_fcs_got != rx_fcs_exp) {
+        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4,
+                            "FCS 32: 0x%08x (incorrect, should be 0x%08x)",
+                            rx_fcs_got, rx_fcs_exp);
+      } else {
+        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4,
+                            "FCS 32: 0x%08x (correct)",
+                            rx_fcs_got);
+      }
     }
-    return (fcs ^ 0xffffffff);
+    break;
+
+  default:
+   g_assert_not_reached();
+   next_tvb = NULL;
+  }
+
+  return next_tvb;
 }
 
 void
@@ -2827,11 +2891,7 @@ dissect_ppp_hdlc( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
   proto_tree *fh_tree = NULL;
   guint8     byte0;
   int        proto_offset;
-  gint       len, reported_len;
   tvbuff_t  *next_tvb;
-  int        rx_fcs_offset;
-  guint32    rx_fcs_exp;
-  guint32    rx_fcs_got;
 
   byte0 = tvb_get_guint8(tvb, 0);
   if (byte0 == CHDLC_ADDR_UNICAST || byte0 == CHDLC_ADDR_MULTICAST) {
@@ -2892,124 +2952,7 @@ dissect_ppp_hdlc( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
     }
   }
 
-  /*
-   * Remove the FCS, if any, from the packet data.
-   */
-  switch (ppp_fcs_decode) {
-
-  case NO_FCS:
-    next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1);
-    break;
-
-  case FCS_16:
-    /*
-     * Do we have the entire packet, and does it include a 2-byte FCS?
-     */
-    len = tvb_length_remaining(tvb, proto_offset);
-    reported_len = tvb_reported_length_remaining(tvb, proto_offset);
-    if (reported_len < 2 || len < 0) {
-      /*
-       * The packet is claimed not to even have enough data for a 2-byte FCS,
-       * or we're already past the end of the captured data.
-       * Don't slice anything off.
-       */
-      next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1);
-    } else if (len < reported_len) {
-      /*
-       * The packet is claimed to have enough data for a 2-byte FCS, but
-       * we didn't capture all of the packet.
-       * Slice off the 2-byte FCS from the reported length, and trim the
-       * captured length so it's no more than the reported length; that
-       * will slice off what of the FCS, if any, is in the captured
-       * length.
-       */
-      reported_len -= 2;
-      if (len > reported_len)
-        len = reported_len;
-      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
-    } else {
-      /*
-       * We have the entire packet, and it includes a 2-byte FCS.
-       * Slice it off.
-       */
-      len -= 2;
-      reported_len -= 2;
-      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
-
-      /*
-       * Compute the FCS and put it into the tree.
-       */
-      rx_fcs_offset = proto_offset + len;
-      rx_fcs_exp = fcs16(0xFFFF, tvb);
-      rx_fcs_got = tvb_get_letohs(tvb, rx_fcs_offset);
-      if (rx_fcs_got != rx_fcs_exp) {
-        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2,
-                            "FCS 16: 0x%04x (incorrect, should be 0x%04x)",
-                            rx_fcs_got, rx_fcs_exp);
-      } else {
-        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2,
-                            "FCS 16: 0x%04x (correct)",
-                            rx_fcs_got);
-      }
-    }
-    break;
-
-  case FCS_32:
-    /*
-     * Do we have the entire packet, and does it include a 4-byte FCS?
-     */
-    len = tvb_length_remaining(tvb, proto_offset);
-    reported_len = tvb_reported_length_remaining(tvb, proto_offset);
-    if (reported_len < 4) {
-      /*
-       * The packet is claimed not to even have enough data for a 4-byte FCS.
-       * Just pass on the tvbuff as is.
-       */
-      next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1);
-    } else if (len < reported_len) {
-      /*
-       * The packet is claimed to have enough data for a 4-byte FCS, but
-       * we didn't capture all of the packet.
-       * Slice off the 4-byte FCS from the reported length, and trim the
-       * captured length so it's no more than the reported length; that
-       * will slice off what of the FCS, if any, is in the captured
-       * length.
-       */
-      reported_len -= 4;
-      if (len > reported_len)
-        len = reported_len;
-      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
-    } else {
-      /*
-       * We have the entire packet, and it includes a 4-byte FCS.
-       * Slice it off.
-       */
-      len -= 4;
-      reported_len -= 4;
-      next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len);
-
-      /*
-       * Compute the FCS and put it into the tree.
-       */
-      rx_fcs_offset = proto_offset + len;
-      rx_fcs_exp = fcs32(0xFFFFFFFF, tvb);
-      rx_fcs_got = tvb_get_letohl(tvb, rx_fcs_offset);
-      if (rx_fcs_got != rx_fcs_exp) {
-        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4,
-                            "FCS 32: 0x%08x (incorrect, should be 0x%08x)",
-                            rx_fcs_got, rx_fcs_exp);
-      } else {
-        proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4,
-                            "FCS 32: 0x%08x (correct)",
-                            rx_fcs_got);
-      }
-    }
-    break;
-
-  default:
-   g_assert_not_reached();
-   next_tvb = NULL;
-  }
+  next_tvb = decode_fcs(tvb, fh_tree, ppp_fcs_decode, proto_offset);
 
   dissect_ppp_common(next_tvb, pinfo, tree, fh_tree, ti);
 }
@@ -3262,13 +3205,6 @@ proto_register_ppp(void)
     &ett_ppp,
   };
 
-  static enum_val_t ppp_options[] = {
-    {"None", 0},
-    {"16-Bit", 1},
-    {"32-Bit", 2},
-    {NULL, -1}
-  };
-
   module_t *ppp_module;
 
   proto_ppp = proto_register_protocol("Point-to-Point Protocol", "PPP", "ppp");
@@ -3291,7 +3227,7 @@ proto_register_ppp(void)
 	"PPP Frame Checksum Type",
 	"The type of PPP frame checksum (none, 16-bit, 32-bit)",
 	&ppp_fcs_decode,
-	ppp_options, FALSE);
+	fcs_options, FALSE);
   prefs_register_bool_preference(ppp_module,
 	"decompress_vj",
 	"Decompress Van Jacobson-compressed frames",