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gnrc/ipv6_auto_subnets: add gnrc_ipv6_auto_subnets_eui

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This commit is contained in:
Benjamin Valentin 2024-12-09 16:27:52 +01:00
parent d394f62aaf
commit 24a1417b31
3 changed files with 67 additions and 1 deletions
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1
makefiles/pseudomodules.inc.mk
View File

@ -107,6 +107,7 @@ PSEUDOMODULES += gnrc_dhcpv6_client_simple_pd
## @}
## @}
PSEUDOMODULES += gnrc_ipv6_auto_subnets_auto_init
PSEUDOMODULES += gnrc_ipv6_auto_subnets_eui
PSEUDOMODULES += gnrc_ipv6_auto_subnets_simple
PSEUDOMODULES += gnrc_ipv6_classic
PSEUDOMODULES += gnrc_ipv6_default

4
sys/net/gnrc/Makefile.dep
View File

@ -126,6 +126,10 @@ ifneq (,$(filter gnrc_rpl,$(USEMODULE)))
USEMODULE += evtimer
endif
ifneq (,$(filter gnrc_ipv6_auto_subnets_eui,$(USEMODULE)))
USEMODULE += gnrc_ipv6_auto_subnets_simple
endif
ifneq (,$(filter gnrc_ipv6_auto_subnets_simple,$(USEMODULE)))
USEMODULE += gnrc_ipv6_auto_subnets
endif

63
sys/net/gnrc/routing/ipv6_auto_subnets/gnrc_ipv6_auto_subnets.c
View File

@ -83,6 +83,16 @@
* The upstream network will be automatically chosen as the one that first
* receives a router advertisement.
*
* If only a single level of downstream routers exists and a sufficiently small
* upstream prefix is provided, we can skip the synchronisation and instead derive
* the *prefix* from the EUI of the downstream interface.
*
* e.g. given a prefix `fd12::/16` a router with a downstream interface with the
* layer 2 address `12:84:0C:87:1F:B7` would create the prefix `fd12:1284:c87:1fb7::/64`
* for the downstream network.
*
* To enable this behavior, chose the `gnrc_ipv6_auto_subnets_eui` module.
*
* @{
*
* @file
@ -100,6 +110,12 @@
#include "random.h"
#include "xtimer.h"
/* If we derive the subnet from the interface's EUI, we have to use all
available prefix bits to ensure uniqueness */
#if IS_USED(MODULE_GNRC_IPV6_AUTO_SUBNETS_EUI)
#define CONFIG_GNRC_IPV6_AUTO_SUBNETS_PREFIX_MIN_LEN (64)
#endif
/**
* @brief Port for the custom UDP sync protocol
*/
@ -305,6 +321,40 @@ static void _init_sub_prefix(ipv6_addr_t *out,
out->u8[bytes] |= idx << shift;
}
static void _init_sub_prefix_uid(ipv6_addr_t *out,
const ipv6_addr_t *prefix, uint8_t bits,
const uint8_t *uid, uint8_t uid_len)
{
uint8_t out_bytes = 64 / 8;
uint8_t bytes = (bits + 7) / 8;
uint8_t rem = bits % 8;
/* first copy old prefix */
memset(out, 0, sizeof(*out));
ipv6_addr_init_prefix(out, prefix, bits);
/* If the UID does not fit, truncate it */
if (uid_len > out_bytes - bytes) {
/* we can use some bits of the first byte */
if (rem) {
--bytes;
}
/* calculate by how many bytes the UID is too large */
uint8_t uid_overhang = uid_len - (out_bytes - bytes);
uid += uid_overhang;
uid_len -= uid_overhang;
if (rem) {
uint8_t mask = 0xff >> rem;
out->u8[bytes++] |= *uid++ & mask;
--uid_len;
}
}
memcpy(&out->u8[bytes], uid, uid_len);
}
/* returns true if a new prefix was added, false if nothing changed */
static bool _remove_old_prefix(gnrc_netif_t *netif,
const ipv6_addr_t *pfx, uint8_t pfx_len,
@ -393,7 +443,18 @@ static void _configure_subnets(uint8_t subnets, uint8_t start_idx, gnrc_netif_t
}
/* create subnet from upstream prefix */
_init_sub_prefix(&new_prefix, prefix, prefix_len, ++start_idx, subnet_len);
if (IS_USED(MODULE_GNRC_IPV6_AUTO_SUBNETS_EUI)) {
uint8_t hwaddr[GNRC_NETIF_L2ADDR_MAXLEN];
int res = netif_get_opt(&downstream->netif, NETOPT_ADDRESS, 0,
hwaddr, sizeof(hwaddr));
if (res <= 0) {
DEBUG("auto_subnets: can't get l2 address from netif %u\n", downstream->pid);
continue;
}
_init_sub_prefix_uid(&new_prefix, prefix, prefix_len, hwaddr, res);
} else {
_init_sub_prefix(&new_prefix, prefix, prefix_len, ++start_idx, subnet_len);
}
DEBUG("auto_subnets: configure prefix %s/%u on %u\n",
ipv6_addr_to_str(addr_str, &new_prefix, sizeof(addr_str)),