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         { "v245", NAMING_V245 },
  15         /* … add more schemes here, as the logic to name devices is updated … */
  16 };
  17
  18 static const NamingScheme* naming_scheme_from_name(const char *name) {
  19         size_t i;
  20
  21         if (streq(name, "latest"))
  22                 return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
  23
  24         for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
  25                 if (streq(naming_schemes[i].name, name))
  26                         return naming_schemes + i;
  27
  28         return NULL;
  29 }
  30
  31 const NamingScheme* naming_scheme(void) {
  32         static const NamingScheme *cache = NULL;
  33         _cleanup_free_ char *buffer = NULL;
  34         const char *e, *k;
  35
  36         if (cache)
  37                 return cache;
  38
  39         /* Acquire setting from the kernel command line */
  40         (void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
  41
  42         /* Also acquire it from an env var */
  43         e = getenv("NET_NAMING_SCHEME");
  44         if (e) {
  45                 if (*e == ':') {
  46                         /* If prefixed with ':' the kernel cmdline takes precedence */
  47                         k = buffer ?: e + 1;
  48                 } else
  49                         k = e; /* Otherwise the env var takes precedence */
  50         } else
  51                 k = buffer;
  52
  53         if (k) {
  54                 cache = naming_scheme_from_name(k);
  55                 if (cache) {
  56                         log_info("Using interface naming scheme '%s'.", cache->name);
  57                         return cache;
  58                 }
  59
  60                 log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
  61         }
  62
  63         cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
  64         assert(cache);
  65         log_info("Using default interface naming scheme '%s'.", cache->name);
  66
  67         return cache;
  68 }