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Member "portfwd-0.29/src/net_portion.cc" (5 May 2002, 1522 Bytes) of package /linux/privat/old/portfwd-0.29.tar.gz:

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    1 /*
    2   net_portion.cc
    3 
    4   $Id: net_portion.cc,v 1.2 2002/05/05 03:30:56 evertonm Exp $
    5  */
    6 
    7 #include <syslog.h>
    8 #include "util.h"
    9 #include "addr.h"
   10 #include "net_portion.h"
   11 
   12 net_portion::net_portion(struct ip_addr addr, short m_len)
   13 {
   14   address  = addr;
   15   mask_len = m_len;
   16 
   17   /*
   18    * Fix last significant byte of mask here so it is ready on compare time.
   19    */
   20   char last = mask_len >> 3; /* last = mask_len / 8 */
   21   if (last < address.len)
   22     address.addr[last] &= (char) (0xFF << (8 - (mask_len & 7)));
   23 }
   24 
   25 void net_portion::show() const
   26 {
   27   show_addr(&address);
   28   syslog(LOG_INFO, "/%d", mask_len);
   29 }
   30 
   31 /*
   32  * Verifica se um endereco IP pertence `a rede.
   33  */
   34 int net_portion::owns(const struct ip_addr *ip) const
   35 {
   36   char *net_a, *net_pastend;
   37   char *ip_a;
   38   char len, left;
   39 
   40   /* 
   41    * Compara comprimento de endereco.
   42    */
   43   if (address.len != ip->len)
   44     return 0;
   45 
   46   /*
   47    * Compara todos os bytes, exceto o ultimo.
   48    */
   49   len = mask_len >> 3; /* mask_len / 8 */
   50   net_a = address.addr;
   51   net_pastend = net_a + len;
   52   ip_a = ip->addr;
   53   for (; net_a < net_pastend; ++net_a, ++ip_a)
   54     if (*net_a != *ip_a)
   55       return 0;
   56 
   57   /*
   58    * left = mask_len % 8 = numero de uns `a esquerda
   59    */
   60   left = mask_len & 7;
   61   if (!left)
   62     return -1;
   63 
   64   /*
   65    * Compara ultimo byte.
   66    *
   67    * 8 - ()       => numero de zeros `a direta
   68    * 0xFF << ()   => insere zeros `a direta
   69    * *ip_a & ()   => desconsidera bits que sejam zero
   70    */
   71   return *net_a == (*ip_a & (char) (0xFF << (8 - left)));
   72 }
   73 
   74 /* Eof: net_portion.cc */