Return to cksum.c CVS log

Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / hping2

Annotation of embedaddon/hping2/cksum.c, revision 1.1.1.1

1.1       misho       1: /* 
                      2:  * $smu-mark$ 
                      3:  * $name: cksum.c$ 
                      4:  * $author: Salvatore Sanfilippo <antirez@invece.org>$ 
                      5:  * $copyright: Copyright (C) 1999 by Salvatore Sanfilippo$ 
                      6:  * $license: This software is under GPL version 2 of license$ 
                      7:  * $date: Fri Nov  5 11:55:47 MET 1999$ 
                      8:  * $rev: 8$ 
                      9:  */ 
                     10: 
                     11: #include "hping2.h"    /* only for arch semi-indipendent data types */
                     12: #include "globals.h"
                     13: 
                     14: /*
                     15:  * from R. Stevens's Network Programming
                     16:  */
                     17: __u16 cksum(__u16 *buf, int nbytes)
                     18: {
                     19:        __u32 sum;
                     20:        __u16 oddbyte;
                     21: 
                     22:        sum = 0;
                     23:        while (nbytes > 1) {
                     24:                sum += *buf++;
                     25:                nbytes -= 2;
                     26:        }
                     27: 
                     28:        if (nbytes == 1) {
                     29:                oddbyte = 0;
                     30:                *((__u16 *) &oddbyte) = *(__u16 *) buf;
                     31:                sum += oddbyte;
                     32:        }
                     33: 
                     34:        sum = (sum >> 16) + (sum & 0xffff);
                     35:        sum += (sum >> 16);
                     36: 
                     37:        /* return a bad checksum with --badcksum option */
                     38:        if (opt_badcksum) sum ^= 0x5555;
                     39: 
                     40:        return (__u16) ~sum;
                     41: }