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         { "v246", NAMING_V246 },
  16         /* … add more schemes here, as the logic to name devices is updated … */
  17 };
  18
  19 static const NamingScheme* naming_scheme_from_name(const char *name) {
  20         size_t i;
  21
  22         if (streq(name, "latest"))
  23                 return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
  24
  25         for (i = 0; i < ELEMENTSOF(naming_schemes); i++)
  26                 if (streq(naming_schemes[i].name, name))
  27                         return naming_schemes + i;
  28
  29         return NULL;
  30 }
  31
  32 const NamingScheme* naming_scheme(void) {
  33         static const NamingScheme *cache = NULL;
  34         _cleanup_free_ char *buffer = NULL;
  35         const char *e, *k;
  36
  37         if (cache)
  38                 return cache;
  39
  40         /* Acquire setting from the kernel command line */
  41         (void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
  42
  43         /* Also acquire it from an env var */
  44         e = getenv("NET_NAMING_SCHEME");
  45         if (e) {
  46                 if (*e == ':') {
  47                         /* If prefixed with ':' the kernel cmdline takes precedence */
  48                         k = buffer ?: e + 1;
  49                 } else
  50                         k = e; /* Otherwise the env var takes precedence */
  51         } else
  52                 k = buffer;
  53
  54         if (k) {
  55                 cache = naming_scheme_from_name(k);
  56                 if (cache) {
  57                         log_info("Using interface naming scheme '%s'.", cache->name);
  58                         return cache;
  59                 }
  60
  61                 log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
  62         }
  63
  64         cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
  65         assert(cache);
  66         log_info("Using default interface naming scheme '%s'.", cache->name);
  67
  68         return cache;
  69 }