src/shared/netif-naming-scheme.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   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         /* … add more schemes here, as the logic to name devices is updated … */
  15 };
  16
  17 static const NamingScheme* naming_scheme_from_name(const char *name) {
  18         size_t i;
  19
  20         if (streq(name, "latest"))
  21                 return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
  22
  23         for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
  24                 if (streq(naming_schemes[i].name, name))
  25                         return naming_schemes + i;
  26
  27         return NULL;
  28 }
  29
  30 const NamingScheme* naming_scheme(void) {
  31         static const NamingScheme *cache = NULL;
  32         _cleanup_free_ char *buffer = NULL;
  33         const char *e, *k;
  34
  35         if (cache)
  36                 return cache;
  37
  38         /* Acquire setting from the kernel command line */
  39         (void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
  40
  41         /* Also acquire it from an env var */
  42         e = getenv("NET_NAMING_SCHEME");
  43         if (e) {
  44                 if (*e == ':') {
  45                         /* If prefixed with ':' the kernel cmdline takes precedence */
  46                         k = buffer ?: e + 1;
  47                 } else
  48                         k = e; /* Otherwise the env var takes precedence */
  49         } else
  50                 k = buffer;
  51
  52         if (k) {
  53                 cache = naming_scheme_from_name(k);
  54                 if (cache) {
  55                         log_info("Using interface naming scheme '%s'.", cache->name);
  56                         return cache;
  57                 }
  58
  59                 log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
  60         }
  61
  62         cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
  63         assert(cache);
  64         log_info("Using default interface naming scheme '%s'.", cache->name);
  65
  66         return cache;
  67 }