ref: 4a92a8f6b2502750a69e87d398ffb2f069103bf4
dir: /sys/src/libip/classmask.c/
#include <u.h> #include <libc.h> #include <ip.h> static uchar classmask[4][16] = { 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0x00,0x00,0x00, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0x00,0x00,0x00, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0x00,0x00, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0xff, 0xff,0xff,0xff,0x00, }; static uchar v6loopback[IPaddrlen] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01 }; static uchar v6linklocal[IPaddrlen] = { 0xfe, 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; static uchar v6linklocalmask[IPaddrlen] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0, 0, 0, 0, 0, 0, 0, 0 }; static int v6llpreflen = 8; /* link-local prefix length in bytes */ static uchar v6multicast[IPaddrlen] = { 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; static uchar v6multicastmask[IPaddrlen] = { 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; static int v6mcpreflen = 1; /* multicast prefix length */ static uchar v6solicitednode[IPaddrlen] = { 0xff, 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01, 0xff, 0, 0, 0 }; static uchar v6solicitednodemask[IPaddrlen] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x0, 0x0, 0x0 }; static int v6snpreflen = 13; uchar* defmask(uchar *ip) { if(isv4(ip)) return classmask[ip[IPv4off]>>6]; else { if(ipcmp(ip, v6loopback) == 0) return IPallbits; else if(memcmp(ip, v6linklocal, v6llpreflen) == 0) return v6linklocalmask; else if(memcmp(ip, v6solicitednode, v6snpreflen) == 0) return v6solicitednodemask; else if(memcmp(ip, v6multicast, v6mcpreflen) == 0) return v6multicastmask; return IPallbits; } } void maskip(uchar *from, uchar *mask, uchar *to) { int i; for(i = 0; i < IPaddrlen; i++) to[i] = from[i] & mask[i]; }