src/shared/netif-naming-scheme.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include "alloc-util.h"
   4 #include "netif-naming-scheme.h"
   5 #include "proc-cmdline.h"
   6 #include "string-util.h"
   7
   8 static const NamingScheme naming_schemes[] = {
   9         { "v238", NAMING_V238 },
  10         { "v239", NAMING_V239 },
  11         { "v240", NAMING_V240 },
  12         { "v241", NAMING_V241 },
  13         { "v243", NAMING_V243 },
  14         { "v245", NAMING_V245 },
  15         { "v247", NAMING_V247 },
  16         { "v249", NAMING_V249 },
  17         /* … add more schemes here, as the logic to name devices is updated … */
  18 };
  19
  20 static const NamingScheme* naming_scheme_from_name(const char *name) {
  21         size_t i;
  22
  23         if (streq(name, "latest"))
  24                 return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
  25
  26         for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
  27                 if (streq(naming_schemes[i].name, name))
  28                         return naming_schemes + i;
  29
  30         return NULL;
  31 }
  32
  33 const NamingScheme* naming_scheme(void) {
  34         static const NamingScheme *cache = NULL;
  35         _cleanup_free_ char *buffer = NULL;
  36         const char *e, *k;
  37
  38         if (cache)
  39                 return cache;
  40
  41         /* Acquire setting from the kernel command line */
  42         (void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
  43
  44         /* Also acquire it from an env var */
  45         e = getenv("NET_NAMING_SCHEME");
  46         if (e) {
  47                 if (*e == ':') {
  48                         /* If prefixed with ':' the kernel cmdline takes precedence */
  49                         k = buffer ?: e + 1;
  50                 } else
  51                         k = e; /* Otherwise the env var takes precedence */
  52         } else
  53                 k = buffer;
  54
  55         if (k) {
  56                 cache = naming_scheme_from_name(k);
  57                 if (cache) {
  58                         log_info("Using interface naming scheme '%s'.", cache->name);
  59                         return cache;
  60                 }
  61
  62                 log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
  63         }
  64
  65         cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
  66         assert(cache);
  67         log_info("Using default interface naming scheme '%s'.", cache->name);
  68
  69         return cache;
  70 }