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#include <u.h>
#include <libc.h>
#include <ctype.h>
typedef struct IPNet IPNet;
struct IPNet
{
u32int addr;
u32int mask;
u32int minaddr;
u32int maxaddr;
u32int bcast;
uint nhosts;
int cidr;
};
#pragma varargck type "I" u32int
#pragma varargck type "N" IPNet
int
Ifmt(Fmt *f)
{
uchar ip4[4];
u32int addr;
addr = va_arg(f->args, u32int);
ip4[0] = addr>>24 & 0xff;
ip4[1] = addr>>16 & 0xff;
ip4[2] = addr>>8 & 0xff;
ip4[3] = addr & 0xff;
return fmtprint(f, "%d.%d.%d.%d", ip4[0], ip4[1], ip4[2], ip4[3]);
}
int
Nfmt(Fmt *f)
{
IPNet net;
int n;
net = va_arg(f->args, IPNet);
n = fmtprint(f, "network %I\n", net.addr);
n += fmtprint(f, "netmask %I\n", net.mask);
n += fmtprint(f, "minaddr %I\n", net.minaddr);
n += fmtprint(f, "maxaddr %I\n", net.maxaddr);
n += fmtprint(f, "bcast %I\n", net.bcast);
n += fmtprint(f, "hosts %d\n", net.nhosts);
n += fmtprint(f, "cidr %d\n", net.cidr);
return n;
}
int
countones(u32int addr)
{
int cnt, shift;
for(cnt = 0, shift = 31; shift >= 0; shift--)
if((addr & 1<<shift) != 0)
cnt++;
return cnt;
}
/* returns the most-significant ones */
int
countmsones(u32int addr)
{
int cnt, shift;
for(cnt = 0, shift = 31; cnt < 32 && (addr & 1<<shift) != 0; cnt++, shift--)
;
return cnt;
}
u32int
getip4(char *s)
{
u32int addr;
int octets;
addr = 0;
octets = 4;
do{
if(!isdigit(*s))
sysfatal("wrong ip address: expected a number");
addr |= strtoul(s, &s, 10) << --octets*8;
if(octets > 0 && *s != '.')
sysfatal("wrong ip address: expected a dot");
}while(*s++ && octets > 0);
return addr;
}
int
checkmask(u32int mask)
{
if(countones(mask) != countmsones(mask))
return -1;
return 0;
}
void
usage(void)
{
fprint(2, "usage: %s addr mask\n", argv0);
exits("usage");
}
void
main(int argc, char *argv[])
{
IPNet net;
u32int addr, mask;
int cidr;
fmtinstall('I', Ifmt);
fmtinstall('N', Nfmt);
ARGBEGIN{
default: usage();
}ARGEND;
if(argc != 2)
usage();
addr = getip4(argv[0]);
if(strlen(argv[1]) <= 2){
cidr = strtol(argv[1], nil, 10);
assert(cidr > 0 && cidr <= 32);
mask = ~0 << (32-cidr);
}else{
mask = getip4(argv[1]);
if(checkmask(mask) < 0)
sysfatal("invalid mask");
}
net.addr = addr&mask;
net.mask = mask;
net.bcast = addr|~mask;
net.minaddr = net.addr+1;
net.maxaddr = net.bcast-1;
net.nhosts = net.maxaddr-net.minaddr;
net.cidr = countmsones(net.mask);
print("%N", net);
exits(nil);
}
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