X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/96977962e98d44c5144164e2286434418ded0e30..refs/pull/482/head:/checksum.c

diff --git a/checksum.c b/checksum.c
index f441be3d..0829fbe6 100644
--- a/checksum.c
+++ b/checksum.c
@@ -17,32 +17,83 @@
  * Original code by Hannes Gredler (hannes@juniper.net)
  */
 
-#ifndef lint
-static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/tcpdump/checksum.c,v 1.4 2006-09-25 09:23:32 hannes Exp $";
-#endif
-
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
 
-#include <tcpdump-stdinc.h>
+#include <netdissect-stdinc.h>
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <assert.h>
 
-#include "interface.h"
+#include "netdissect.h"
 
-#define CRC10_POLYNOMIAL 0x633
-static u_int16_t crc10_table[256];
+/*
+ * CRC-10 table generated using the following Python snippet:
+
+import sys
+
+crc_table = []
+for i in range(256):
+	accum = i << 2
+	for j in range(8):
+		accum <<= 1
+		if accum & 0x400:
+			accum ^= 0x633
+	crc_table.append(accum)
+
+for i in range(len(crc_table)/8):
+	for j in range(8):
+		sys.stdout.write("0x%04x, " % crc_table[i*8+j])
+	sys.stdout.write("\n")
+
+ */
+static const uint16_t crc10_table[256] =
+{
+	0x0000, 0x0233, 0x0255, 0x0066, 0x0299, 0x00aa, 0x00cc, 0x02ff,
+	0x0301, 0x0132, 0x0154, 0x0367, 0x0198, 0x03ab, 0x03cd, 0x01fe,
+	0x0031, 0x0202, 0x0264, 0x0057, 0x02a8, 0x009b, 0x00fd, 0x02ce,
+	0x0330, 0x0103, 0x0165, 0x0356, 0x01a9, 0x039a, 0x03fc, 0x01cf,
+	0x0062, 0x0251, 0x0237, 0x0004, 0x02fb, 0x00c8, 0x00ae, 0x029d,
+	0x0363, 0x0150, 0x0136, 0x0305, 0x01fa, 0x03c9, 0x03af, 0x019c,
+	0x0053, 0x0260, 0x0206, 0x0035, 0x02ca, 0x00f9, 0x009f, 0x02ac,
+	0x0352, 0x0161, 0x0107, 0x0334, 0x01cb, 0x03f8, 0x039e, 0x01ad,
+	0x00c4, 0x02f7, 0x0291, 0x00a2, 0x025d, 0x006e, 0x0008, 0x023b,
+	0x03c5, 0x01f6, 0x0190, 0x03a3, 0x015c, 0x036f, 0x0309, 0x013a,
+	0x00f5, 0x02c6, 0x02a0, 0x0093, 0x026c, 0x005f, 0x0039, 0x020a,
+	0x03f4, 0x01c7, 0x01a1, 0x0392, 0x016d, 0x035e, 0x0338, 0x010b,
+	0x00a6, 0x0295, 0x02f3, 0x00c0, 0x023f, 0x000c, 0x006a, 0x0259,
+	0x03a7, 0x0194, 0x01f2, 0x03c1, 0x013e, 0x030d, 0x036b, 0x0158,
+	0x0097, 0x02a4, 0x02c2, 0x00f1, 0x020e, 0x003d, 0x005b, 0x0268,
+	0x0396, 0x01a5, 0x01c3, 0x03f0, 0x010f, 0x033c, 0x035a, 0x0169,
+	0x0188, 0x03bb, 0x03dd, 0x01ee, 0x0311, 0x0122, 0x0144, 0x0377,
+	0x0289, 0x00ba, 0x00dc, 0x02ef, 0x0010, 0x0223, 0x0245, 0x0076,
+	0x01b9, 0x038a, 0x03ec, 0x01df, 0x0320, 0x0113, 0x0175, 0x0346,
+	0x02b8, 0x008b, 0x00ed, 0x02de, 0x0021, 0x0212, 0x0274, 0x0047,
+	0x01ea, 0x03d9, 0x03bf, 0x018c, 0x0373, 0x0140, 0x0126, 0x0315,
+	0x02eb, 0x00d8, 0x00be, 0x028d, 0x0072, 0x0241, 0x0227, 0x0014,
+	0x01db, 0x03e8, 0x038e, 0x01bd, 0x0342, 0x0171, 0x0117, 0x0324,
+	0x02da, 0x00e9, 0x008f, 0x02bc, 0x0043, 0x0270, 0x0216, 0x0025,
+	0x014c, 0x037f, 0x0319, 0x012a, 0x03d5, 0x01e6, 0x0180, 0x03b3,
+	0x024d, 0x007e, 0x0018, 0x022b, 0x00d4, 0x02e7, 0x0281, 0x00b2,
+	0x017d, 0x034e, 0x0328, 0x011b, 0x03e4, 0x01d7, 0x01b1, 0x0382,
+	0x027c, 0x004f, 0x0029, 0x021a, 0x00e5, 0x02d6, 0x02b0, 0x0083,
+	0x012e, 0x031d, 0x037b, 0x0148, 0x03b7, 0x0184, 0x01e2, 0x03d1,
+	0x022f, 0x001c, 0x007a, 0x0249, 0x00b6, 0x0285, 0x02e3, 0x00d0,
+	0x011f, 0x032c, 0x034a, 0x0179, 0x0386, 0x01b5, 0x01d3, 0x03e0,
+	0x021e, 0x002d, 0x004b, 0x0278, 0x0087, 0x02b4, 0x02d2, 0x00e1
+};
 
 static void
 init_crc10_table(void)
-{   
+{
+#define CRC10_POLYNOMIAL 0x633
     register int i, j;
-    register u_int16_t accum;
-    
+    register uint16_t accum;
+    uint16_t verify_crc10_table[256];
+
     for ( i = 0;  i < 256;  i++ )
     {
         accum = ((unsigned short) i << 2);
@@ -50,13 +101,16 @@ init_crc10_table(void)
         {
             if ((accum <<= 1) & 0x400) accum ^= CRC10_POLYNOMIAL;
         }
-        crc10_table[i] = accum;
+        verify_crc10_table[i] = accum;
     }
-    return;
+    assert(memcmp(verify_crc10_table,
+				  crc10_table,
+				  sizeof(verify_crc10_table)) == 0);
+#undef CRC10_POLYNOMIAL
 }
 
-u_int16_t
-verify_crc10_cksum(u_int16_t accum, const u_char *p, int length)
+uint16_t
+verify_crc10_cksum(uint16_t accum, const u_char *p, int length)
 {
     register int i;
 
@@ -81,42 +135,40 @@ init_checksum(void) {
  * Creates the OSI Fletcher checksum. See 8473-1, Appendix C, section C.3.
  * The checksum field of the passed PDU does not need to be reset to zero.
  */
-u_int16_t
-create_osi_cksum (const u_int8_t *pptr, int checksum_offset, int length)
+uint16_t
+create_osi_cksum (const uint8_t *pptr, int checksum_offset, int length)
 {
 
     int x;
     int y;
-    u_int32_t mul;
-    u_int32_t c0;
-    u_int32_t c1;
-    u_int16_t checksum;
-    int index;
-
-    checksum = 0;
+    uint32_t mul;
+    uint32_t c0;
+    uint32_t c1;
+    uint16_t checksum;
+    int idx;
 
     c0 = 0;
     c1 = 0;
 
-    for (index = 0; index < length; index++) {
+    for (idx = 0; idx < length; idx++) {
         /*
          * Ignore the contents of the checksum field.
          */
-        if (index == checksum_offset ||
-            index == checksum_offset+1) {
+        if (idx == checksum_offset ||
+            idx == checksum_offset+1) {
             c1 += c0;
             pptr++;
         } else {
             c0 = c0 + *(pptr++);
             c1 += c0;
-        } 
+        }
     }
 
     c0 = c0 % 255;
     c1 = c1 % 255;
 
     mul = (length - checksum_offset)*(c0);
-  
+
     x = mul - c0 - c1;
     y = c1 - mul - 1;
 
@@ -132,6 +184,6 @@ create_osi_cksum (const u_int8_t *pptr, int checksum_offset, int length)
 
     y &= 0x00FF;
     checksum = ((x << 8) | y);
-  
+
     return checksum;
 }