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 #ifdef _DEFAULT_NET_NAMING_SCHEME_TEST
   9 /* The primary purpose of this check is to verify that _DEFAULT_NET_NAMING_SCHEME_TEST
  10  * is a valid identifier. If an invalid name is given during configuration, this will
  11  * fail with a name error. */
  12 assert_cc(_DEFAULT_NET_NAMING_SCHEME_TEST >= 0);
  13 #endif
  14
  15 static const NamingScheme naming_schemes[] = {
  16         { "v238", NAMING_V238 },
  17         { "v239", NAMING_V239 },
  18         { "v240", NAMING_V240 },
  19         { "v241", NAMING_V241 },
  20         { "v243", NAMING_V243 },
  21         { "v245", NAMING_V245 },
  22         { "v247", NAMING_V247 },
  23         { "v249", NAMING_V249 },
  24         { "v250", NAMING_V250 },
  25         /* … add more schemes here, as the logic to name devices is updated … */
  26
  27         EXTRA_NET_NAMING_MAP
  28 };
  29
  30 const NamingScheme* naming_scheme_from_name(const char *name) {
  31         /* "latest" may either be defined explicitly by the extra map, in which case we we will find it in
  32          * the table like any other name. After iterating through the table, we check for "latest" again,
  33          * which means that if not mapped explicitly, it maps to the last defined entry, whatever that is. */
  34
  35         for (size_t i = 0; i < ELEMENTSOF(naming_schemes); i++)
  36                 if (streq(naming_schemes[i].name, name))
  37                         return naming_schemes + i;
  38
  39         if (streq(name, "latest"))
  40                 return naming_schemes + ELEMENTSOF(naming_schemes) - 1;
  41
  42         return NULL;
  43 }
  44
  45 const NamingScheme* naming_scheme(void) {
  46         static const NamingScheme *cache = NULL;
  47         _cleanup_free_ char *buffer = NULL;
  48         const char *e, *k;
  49
  50         if (cache)
  51                 return cache;
  52
  53         /* Acquire setting from the kernel command line */
  54         (void) proc_cmdline_get_key("net.naming-scheme", 0, &buffer);
  55
  56         /* Also acquire it from an env var */
  57         e = getenv("NET_NAMING_SCHEME");
  58         if (e) {
  59                 if (*e == ':') {
  60                         /* If prefixed with ':' the kernel cmdline takes precedence */
  61                         k = buffer ?: e + 1;
  62                 } else
  63                         k = e; /* Otherwise the env var takes precedence */
  64         } else
  65                 k = buffer;
  66
  67         if (k) {
  68                 cache = naming_scheme_from_name(k);
  69                 if (cache) {
  70                         log_info("Using interface naming scheme '%s'.", cache->name);
  71                         return cache;
  72                 }
  73
  74                 log_warning("Unknown interface naming scheme '%s' requested, ignoring.", k);
  75         }
  76
  77         cache = naming_scheme_from_name(DEFAULT_NET_NAMING_SCHEME);
  78         assert(cache);
  79         log_info("Using default interface naming scheme '%s'.", cache->name);
  80
  81         return cache;
  82 }