ref: afadbd7aff255523ef99962dd872caad976b7b08
dir: /libip/eipfmt.c/
#include <u.h>
#include <libc.h>
#include <ip.h>
enum
{
Isprefix= 16,
};
uchar prefixvals[256] =
{
[0x00] 0 | Isprefix,
[0x80] 1 | Isprefix,
[0xC0] 2 | Isprefix,
[0xE0] 3 | Isprefix,
[0xF0] 4 | Isprefix,
[0xF8] 5 | Isprefix,
[0xFC] 6 | Isprefix,
[0xFE] 7 | Isprefix,
[0xFF] 8 | Isprefix,
};
int
eipfmt(Fmt *f)
{
char buf[5*8];
static char *efmt = "%.2ux%.2ux%.2ux%.2ux%.2ux%.2ux";
static char *ifmt = "%d.%d.%d.%d";
uchar *p, ip[16];
ulong *lp;
ushort s;
int i, j, n, eln, eli;
switch(f->r) {
case 'E': /* Ethernet address */
p = va_arg(f->args, uchar*);
snprint(buf, sizeof buf, efmt, p[0], p[1], p[2], p[3], p[4], p[5]);
return fmtstrcpy(f, buf);
case 'I': /* Ip address */
p = va_arg(f->args, uchar*);
common:
if(memcmp(p, v4prefix, 12) == 0){
snprint(buf, sizeof buf, ifmt, p[12], p[13], p[14], p[15]);
return fmtstrcpy(f, buf);
}
/* find longest elision */
eln = eli = -1;
for(i = 0; i < 16; i += 2){
for(j = i; j < 16; j += 2)
if(p[j] != 0 || p[j+1] != 0)
break;
if(j > i && j - i > eln){
eli = i;
eln = j - i;
}
}
/* print with possible elision */
n = 0;
for(i = 0; i < 16; i += 2){
if(i == eli){
n += sprint(buf+n, "::");
i += eln;
if(i >= 16)
break;
} else if(i != 0)
n += sprint(buf+n, ":");
s = (p[i]<<8) + p[i+1];
n += sprint(buf+n, "%ux", s);
}
return fmtstrcpy(f, buf);
case 'i': /* v6 address as 4 longs */
lp = va_arg(f->args, ulong*);
for(i = 0; i < 4; i++)
hnputl(ip+4*i, *lp++);
p = ip;
goto common;
case 'V': /* v4 ip address */
p = va_arg(f->args, uchar*);
snprint(buf, sizeof buf, ifmt, p[0], p[1], p[2], p[3]);
return fmtstrcpy(f, buf);
case 'M': /* ip mask */
p = va_arg(f->args, uchar*);
/* look for a prefix mask */
for(i = 0; i < 16; i++)
if(p[i] != 0xff)
break;
if(i < 16){
if((prefixvals[p[i]] & Isprefix) == 0)
goto common;
for(j = i+1; j < 16; j++)
if(p[j] != 0)
goto common;
n = 8*i + (prefixvals[p[i]] & ~Isprefix);
} else
n = 8*16;
/* got one, use /xx format */
snprint(buf, sizeof buf, "/%d", n);
return fmtstrcpy(f, buf);
}
return fmtstrcpy(f, "(eipfmt)");
}