1 #include <u.h> 2 #include <libc.h> 3 #include <ip.h> 4 5 uchar classmask[4][16] = { 6 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0x00,0x00,0x00, 7 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0x00,0x00,0x00, 8 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0x00,0x00, 9 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0x00, 10 }; 11 12 uchar* 13 defmask(uchar *ip) 14 { 15 return classmask[ip[IPv4off]>>6]; 16 } 17 18 void 19 maskip(uchar *from, uchar *mask, uchar *to) 20 { 21 int i; 22 23 for(i = 0; i < IPaddrlen; i++) 24 to[i] = from[i] & mask[i]; 25 } 26