1 files changed, 57 insertions, 0 deletions
diff --git a/src/shared/netif-naming-scheme.h b/src/shared/netif-naming-scheme.h
new file mode 100644
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+++ b/src/shared/netif-naming-scheme.h
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+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdbool.h>
+
+#include "macro.h"
+
+/* So here's the deal: net_id is supposed to be an exercise in providing stable names for network devices. However, we
+ * also want to keep updating the naming scheme used in future versions of net_id. These two goals of course are
+ * contradictory: on one hand we want things to not change and on the other hand we want them to improve. Our way out
+ * of this dilemma is to introduce the "naming scheme" concept: each time we improve the naming logic we define a new
+ * flag for it. Then, we keep a list of schemes, each identified by a name associated with the flags it implements. Via
+ * a kernel command line and environment variable we then allow the user to pick the scheme they want us to follow:
+ * installers could "freeze" the used scheme at the moment of installation this way.
+ *
+ * Developers: each time you tweak the naming logic here, define a new flag below, and condition the tweak with
+ * it. Each time we do a release we'll then add a new scheme entry and include all newly defined flags.
+ *
+ * Note that this is only half a solution to the problem though: not only udev/net_id gets updated all the time, the
+ * kernel gets too. And thus a kernel that previously didn't expose some sysfs attribute we look for might eventually
+ * do, and thus affect our naming scheme too. Thus, enforcing a naming scheme will make interfacing more stable across
+ * OS versions, but not fully stabilize them. */
+typedef enum NamingSchemeFlags {
+        /* First, the individual features */
+        NAMING_SR_IOV_V            = 1 << 0, /* Use "v" suffix for SR-IOV, see 609948c7043a */
+        NAMING_NPAR_ARI            = 1 << 1, /* Use NPAR "ARI", see 6bc04997b6ea */
+        NAMING_INFINIBAND          = 1 << 2, /* Use "ib" prefix for infiniband, see 938d30aa98df */
+        NAMING_ZERO_ACPI_INDEX     = 1 << 3, /* Use zero acpi_index field, see d81186ef4f6a */
+        NAMING_ALLOW_RERENAMES     = 1 << 4, /* Allow re-renaming of devices, see #9006 */
+        NAMING_STABLE_VIRTUAL_MACS = 1 << 5, /* Use device name to generate MAC, see 6d3646406560 */
+        NAMING_NETDEVSIM           = 1 << 6, /* Generate names for netdevsim devices, see eaa9d507d855 */
+        NAMING_LABEL_NOPREFIX      = 1 << 7, /* Don't prepend ID_NET_LABEL_ONBOARD with interface type prefix */
+        NAMING_NSPAWN_LONG_HASH    = 1 << 8, /* Shorten nspawn interfaces by including 24bit hash, instead of simple truncation  */
+        NAMING_BRIDGE_NO_SLOT      = 1 << 9, /* Don't use PCI hotplug slot information if the corresponding device is a PCI bridge */
+
+        /* And now the masks that combine the features above */
+        NAMING_V238 = 0,
+        NAMING_V239 = NAMING_V238 | NAMING_SR_IOV_V | NAMING_NPAR_ARI,
+        NAMING_V240 = NAMING_V239 | NAMING_INFINIBAND | NAMING_ZERO_ACPI_INDEX | NAMING_ALLOW_RERENAMES,
+        NAMING_V241 = NAMING_V240 | NAMING_STABLE_VIRTUAL_MACS,
+        NAMING_V243 = NAMING_V241 | NAMING_NETDEVSIM | NAMING_LABEL_NOPREFIX,
+        NAMING_V245 = NAMING_V243 | NAMING_NSPAWN_LONG_HASH,
+        NAMING_V247 = NAMING_V245 | NAMING_BRIDGE_NO_SLOT,
+
+        _NAMING_SCHEME_FLAGS_INVALID = -1,
+} NamingSchemeFlags;
+
+typedef struct NamingScheme {
+        const char *name;
+        NamingSchemeFlags flags;
+} NamingScheme;
+
+const NamingScheme* naming_scheme(void);
+
+static inline bool naming_scheme_has(NamingSchemeFlags flags) {
+        return FLAGS_SET(naming_scheme()->flags, flags);
+}