Dogcows Code - chaz/thecheat/blob - cheat_net.m

   1
   2 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   3 // Project:   The Cheat
   4 //
   5 // File:      cheat_net.m
   6 // Created:   Mon Sep 08 2003
   7 //
   8 // Copyright: 2003 Chaz McGarvey.  All rights reserved.
   9 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  10
  11 #include "cheat_net.h"
  12
  13
  14 u_int32_t RandomChecksum()
  15 {
  16         u_int8_t                byte1, byte2, byte3, byte4;
  17         char                    *ptr;
  18
  19         u_int32_t               checksum;
  20         long                    randomValue = random();
  21
  22         byte1 = randomValue & 0xFF;
  23         byte2 = (randomValue >> 8) & 0xFF;
  24         byte3 = (randomValue >> 16) & 0xFF;
  25         byte4 = CountBits( byte1 ) + CountBits( byte2 ) + CountBits( byte3 );
  26
  27         ptr = (char *)(&checksum);
  28
  29         COPY_TO_BUFFER( ptr, &byte1, sizeof(byte1) );
  30         COPY_TO_BUFFER( ptr, &byte2, sizeof(byte2) );
  31         COPY_TO_BUFFER( ptr, &byte3, sizeof(byte3) );
  32         COPY_TO_BUFFER( ptr, &byte4, sizeof(byte4) );
  33
  34         return checksum;
  35 }
  36
  37 char VerifyChecksum( u_int32_t checksum )
  38 {
  39         u_int8_t                byte1, byte2, byte3, byte4;
  40         char                    *ptr = (char *)(&checksum);
  41
  42         COPY_FROM_BUFFER( &byte1, ptr, sizeof(byte1) );
  43         COPY_FROM_BUFFER( &byte2, ptr, sizeof(byte2) );
  44         COPY_FROM_BUFFER( &byte3, ptr, sizeof(byte3) );
  45         COPY_FROM_BUFFER( &byte4, ptr, sizeof(byte4) );
  46
  47         if ( (CountBits( byte1 ) + CountBits( byte2 ) + CountBits( byte3 )) == byte4 )
  48         {
  49                 return 1;
  50         }
  51
  52         NSLog( @"checksum failed" );
  53
  54         return 0;
  55 }
  56
  57 int CountBits( u_int8_t byte )
  58 {
  59         int                             count = 0;
  60         int                             i;
  61
  62         for ( i = 0; i < 8; i++ )
  63         {
  64                 count += byte & 1;
  65
  66                 byte >>= 1;
  67         }
  68
  69         return count;
  70 }
  71
  72
  73 int SendBuffer( int sockfd, char const *buffer, int *length )
  74 {
  75         int                             bytesSent = 0;
  76         int                             bytesLeft = *length;
  77         int                             n = 0;
  78
  79         while( bytesSent < *length )
  80         {
  81                 if ( (n = send( sockfd, buffer+bytesSent, bytesLeft, 0 )) == -1 )
  82                 {
  83                         break;
  84                 }
  85
  86                 bytesSent += n;
  87                 bytesLeft -= n;
  88         }
  89
  90         *length = bytesSent;
  91
  92         return (n == -1)? -1:0;
  93 }
  94
  95 int ReadBuffer( int sockfd, char *buffer, int length )
  96 {
  97         int                             bytesRead = 0;
  98         int                             bytesLeft = length;
  99         int                             n;
 100
 101         while( bytesRead < length )
 102         {
 103                 if ( (n = recv( sockfd, buffer+bytesRead, bytesLeft, 0 )) == -1 || n == 0 )
 104                 {
 105                         return (bytesRead > 0)? bytesRead:n;
 106                 }
 107
 108                 bytesRead += n;
 109                 bytesLeft -= n;
 110         }
 111
 112         return bytesRead;
 113 }