src/network/inet_ntop.c

   1 #include <sys/socket.h>
   2 #include <arpa/inet.h>
   3 #include <errno.h>
   4 #include <stdio.h>
   5 #include <string.h>
   6
   7 const char *inet_ntop(int af, const void *restrict a0, char *restrict s, socklen_t l)
   8 {
   9         const unsigned char *a = a0;
  10         int i, j, max, best;
  11         char buf[100];
  12
  13         switch (af) {
  14         case AF_INET:
  15                 if (snprintf(s, l, "%d.%d.%d.%d", a[0],a[1],a[2],a[3]) < l)
  16                         return s;
  17                 break;
  18         case AF_INET6:
  19                 if (memcmp(a, "\0\0\0\0\0\0\0\0\0\0\377\377", 12))
  20                         snprintf(buf, sizeof buf,
  21                                 "%x:%x:%x:%x:%x:%x:%x:%x",
  22                                 256*a[0]+a[1],256*a[2]+a[3],
  23                                 256*a[4]+a[5],256*a[6]+a[7],
  24                                 256*a[8]+a[9],256*a[10]+a[11],
  25                                 256*a[12]+a[13],256*a[14]+a[15]);
  26                 else
  27                         snprintf(buf, sizeof buf,
  28                                 "%x:%x:%x:%x:%x:%x:%d.%d.%d.%d",
  29                                 256*a[0]+a[1],256*a[2]+a[3],
  30                                 256*a[4]+a[5],256*a[6]+a[7],
  31                                 256*a[8]+a[9],256*a[10]+a[11],
  32                                 a[12],a[13],a[14],a[15]);
  33                 /* Replace longest /(^0|:)[:0]{2,}/ with "::" */
  34                 for (i=best=0, max=2; buf[i]; i++) {
  35                         if (i && buf[i] != ':') continue;
  36                         j = strspn(buf+i, ":0");
  37                         if (j>max) best=i, max=j;
  38                 }
  39                 if (max>3) {
  40                         buf[best] = buf[best+1] = ':';
  41                         memmove(buf+best+2, buf+best+max, i-best-max+1);
  42                 }
  43                 if (strlen(buf) < l) {
  44                         strcpy(s, buf);
  45                         return s;
  46                 }
  47                 break;
  48         default:
  49                 errno = EAFNOSUPPORT;
  50                 return 0;
  51         }
  52         errno = ENOSPC;
  53         return 0;
  54 }