lib/mpls_ntop.c

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 #include <errno.h>
   4 #include <string.h>
   5 #include <sys/types.h>
   6 #include <netinet/in.h>
   7 #include <linux/mpls.h>
   8
   9 #include "utils.h"
  10
  11 static const char *mpls_ntop1(const struct mpls_label *addr, char *buf, size_t buflen)
  12 {
  13         size_t destlen = buflen;
  14         char *dest = buf;
  15         int count = 0;
  16
  17         while (1) {
  18                 uint32_t entry = ntohl(addr[count++].entry);
  19                 uint32_t label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
  20                 int len = snprintf(dest, destlen, "%u", label);
  21
  22                 if (len >= destlen)
  23                         break;
  24
  25                 /* Is this the end? */
  26                 if (entry & MPLS_LS_S_MASK)
  27                         return buf;
  28
  29                 dest += len;
  30                 destlen -= len;
  31                 if (destlen) {
  32                         *dest = '/';
  33                         dest++;
  34                         destlen--;
  35                 }
  36         }
  37         errno = -E2BIG;
  38         return NULL;
  39 }
  40
  41 const char *mpls_ntop(int af, const void *addr, char *buf, size_t buflen)
  42 {
  43         switch(af) {
  44         case AF_MPLS:
  45                 errno = 0;
  46                 return mpls_ntop1((struct mpls_label *)addr, buf, buflen);
  47         default:
  48                 errno = EAFNOSUPPORT;
  49         }
  50
  51         return NULL;
  52 }