sys/src/libip/eipfmt.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <ip.h>
   4
   5 enum
   6 {
   7         Isprefix= 16,
   8 };
   9
  10 uchar prefixvals[256] =
  11 {
  12 [0x00] 0 | Isprefix,
  13 [0x80] 1 | Isprefix,
  14 [0xC0] 2 | Isprefix,
  15 [0xE0] 3 | Isprefix,
  16 [0xF0] 4 | Isprefix,
  17 [0xF8] 5 | Isprefix,
  18 [0xFC] 6 | Isprefix,
  19 [0xFE] 7 | Isprefix,
  20 [0xFF] 8 | Isprefix,
  21 };
  22
  23 int
  24 eipfmt(Fmt *f)
  25 {
  26         char buf[5*8];
  27         static char *efmt = "%.2ux%.2ux%.2ux%.2ux%.2ux%.2ux";
  28         static char *ifmt = "%d.%d.%d.%d";
  29         uchar *p, ip[16];
  30         ulong *lp;
  31         ushort s;
  32         int i, j, n, eln, eli;
  33
  34         switch(f->r) {
  35         case 'E':               /* Ethernet address */
  36                 p = va_arg(f->args, uchar*);
  37                 snprint(buf, sizeof buf, efmt, p[0], p[1], p[2], p[3], p[4], p[5]);
  38                 return fmtstrcpy(f, buf);
  39
  40         case 'I':               /* Ip address */
  41                 p = va_arg(f->args, uchar*);
  42 common:
  43                 if(memcmp(p, v4prefix, 12) == 0){
  44                         snprint(buf, sizeof buf, ifmt, p[12], p[13], p[14], p[15]);
  45                         return fmtstrcpy(f, buf);
  46                 }
  47
  48                 /* find longest elision */
  49                 eln = eli = -1;
  50                 for(i = 0; i < 16; i += 2){
  51                         for(j = i; j < 16; j += 2)
  52                                 if(p[j] != 0 || p[j+1] != 0)
  53                                         break;
  54                         if(j > i && j - i > eln){
  55                                 eli = i;
  56                                 eln = j - i;
  57                         }
  58                 }
  59
  60                 /* print with possible elision */
  61                 n = 0;
  62                 for(i = 0; i < 16; i += 2){
  63                         if(i == eli){
  64                                 n += sprint(buf+n, "::");
  65                                 i += eln;
  66                                 if(i >= 16)
  67                                         break;
  68                         } else if(i != 0)
  69                                 n += sprint(buf+n, ":");
  70                         s = (p[i]<<8) + p[i+1];
  71                         n += sprint(buf+n, "%ux", s);
  72                 }
  73                 return fmtstrcpy(f, buf);
  74
  75         case 'i':               /* v6 address as 4 longs */
  76                 lp = va_arg(f->args, ulong*);
  77                 for(i = 0; i < 4; i++)
  78                         hnputl(ip+4*i, *lp++);
  79                 p = ip;
  80                 goto common;
  81
  82         case 'V':               /* v4 ip address */
  83                 p = va_arg(f->args, uchar*);
  84                 snprint(buf, sizeof buf, ifmt, p[0], p[1], p[2], p[3]);
  85                 return fmtstrcpy(f, buf);
  86
  87         case 'M':               /* ip mask */
  88                 p = va_arg(f->args, uchar*);
  89
  90                 /* look for a prefix mask */
  91                 for(i = 0; i < 16; i++)
  92                         if(p[i] != 0xff)
  93                                 break;
  94                 if(i < 16){
  95                         if((prefixvals[p[i]] & Isprefix) == 0)
  96                                 goto common;
  97                         for(j = i+1; j < 16; j++)
  98                                 if(p[j] != 0)
  99                                         goto common;
 100                         n = 8*i + (prefixvals[p[i]] & ~Isprefix);
 101                 } else
 102                         n = 8*16;
 103
 104                 /* got one, use /xx format */
 105                 snprint(buf, sizeof buf, "/%d", n);
 106                 return fmtstrcpy(f, buf);
 107         }
 108         return fmtstrcpy(f, "(eipfmt)");
 109 }