sys/src/cmd/ip/ppp/ipaux.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <ip.h>
   4 #include <auth.h>
   5 #include "ppp.h"
   6
   7 static  ushort  endian  = 1;
   8 static  uchar*  aendian = (uchar*)&endian;
   9 #define LITTLE  *aendian
  10
  11 ushort
  12 ptclbsum(uchar *addr, int len)
  13 {
  14         ulong losum, hisum, mdsum, x;
  15         ulong t1, t2;
  16
  17         losum = 0;
  18         hisum = 0;
  19         mdsum = 0;
  20
  21         x = 0;
  22         if((uintptr)addr & 1) {
  23                 if(len) {
  24                         hisum += addr[0];
  25                         len--;
  26                         addr++;
  27                 }
  28                 x = 1;
  29         }
  30         while(len >= 16) {
  31                 t1 = *(ushort*)(addr+0);
  32                 t2 = *(ushort*)(addr+2);        mdsum += t1;
  33                 t1 = *(ushort*)(addr+4);        mdsum += t2;
  34                 t2 = *(ushort*)(addr+6);        mdsum += t1;
  35                 t1 = *(ushort*)(addr+8);        mdsum += t2;
  36                 t2 = *(ushort*)(addr+10);       mdsum += t1;
  37                 t1 = *(ushort*)(addr+12);       mdsum += t2;
  38                 t2 = *(ushort*)(addr+14);       mdsum += t1;
  39                 mdsum += t2;
  40                 len -= 16;
  41                 addr += 16;
  42         }
  43         while(len >= 2) {
  44                 mdsum += *(ushort*)addr;
  45                 len -= 2;
  46                 addr += 2;
  47         }
  48         if(x) {
  49                 if(len)
  50                         losum += addr[0];
  51                 if(LITTLE)
  52                         losum += mdsum;
  53                 else
  54                         hisum += mdsum;
  55         } else {
  56                 if(len)
  57                         hisum += addr[0];
  58                 if(LITTLE)
  59                         hisum += mdsum;
  60                 else
  61                         losum += mdsum;
  62         }
  63
  64         losum += hisum >> 8;
  65         losum += (hisum & 0xff) << 8;
  66         while(hisum = losum>>16)
  67                 losum = hisum + (losum & 0xffff);
  68
  69         return losum & 0xffff;
  70 }
  71
  72 ushort
  73 ptclcsum(Block *bp, int offset, int len)
  74 {
  75         uchar *addr;
  76         ulong losum, hisum;
  77         ushort csum;
  78         int odd, blen, x;
  79
  80         /* Correct to front of data area */
  81         while(bp != nil && offset && offset >= BLEN(bp)) {
  82                 offset -= BLEN(bp);
  83                 bp = bp->next;
  84         }
  85         if(bp == nil)
  86                 return 0;
  87
  88         addr = bp->rptr + offset;
  89         blen = BLEN(bp) - offset;
  90
  91         if(bp->next == nil) {
  92                 if(blen < len)
  93                         len = blen;
  94                 return ~ptclbsum(addr, len) & 0xffff;
  95         }
  96
  97         losum = 0;
  98         hisum = 0;
  99
 100         odd = 0;
 101         while(len) {
 102                 x = blen;
 103                 if(len < x)
 104                         x = len;
 105
 106                 csum = ptclbsum(addr, x);
 107                 if(odd)
 108                         hisum += csum;
 109                 else
 110                         losum += csum;
 111                 odd = (odd+x) & 1;
 112                 len -= x;
 113
 114                 bp = bp->next;
 115                 if(bp == nil)
 116                         break;
 117                 blen = BLEN(bp);
 118                 addr = bp->rptr;
 119         }
 120
 121         losum += hisum>>8;
 122         losum += (hisum&0xff)<<8;
 123         while((csum = losum>>16) != 0)
 124                 losum = csum + (losum & 0xffff);
 125
 126         return ~losum & 0xffff;
 127 }
 128
 129 ushort
 130 ipcsum(uchar *addr)
 131 {
 132         int len;
 133         ulong sum;
 134
 135         sum = 0;
 136         len = (addr[0]&0xf)<<2;
 137
 138         while(len > 0) {
 139                 sum += (addr[0]<<8) | addr[1] ;
 140                 len -= 2;
 141                 addr += 2;
 142         }
 143
 144         sum = (sum & 0xffff) + (sum >> 16);
 145         sum = (sum & 0xffff) + (sum >> 16);
 146
 147         return (sum^0xffff);
 148 }