gnrc_ipv6_nib/SLAAC: rfc8981 temporary address (privacy extensions)

sys/include/net/gnrc/ipv6/nib.h

@@ -243,6 +243,18 @@ extern "C" {
  * @brief   Interface down event
  */
 #define GNRC_IPV6_NIB_IFACE_DOWN            (0x4fd5U)
+
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES) || defined(DOXYGEN)
+/**
+ * @brief   Temporary address: regenerate
+ *
+ * This message type is for the event of a regeneration of a temporary address.
+ * The expected message context is a valid off-link entry representing the temporary address prefix.
+ *
+ * @see "REGEN_ADVANCE time units before" - https://www.rfc-editor.org/rfc/rfc8981.html#section-3.6
+ */
+#define GNRC_IPV6_NIB_REGEN_TEMP_ADDR       (0x4fd6U)
+#endif
 /** @} */
 
 /**

sys/include/net/gnrc/ipv6/nib/conf.h

@@ -65,7 +65,7 @@
 # endif
 # ifndef CONFIG_GNRC_IPV6_NIB_NUMOF
 /* only needs to store default router */
-# define CONFIG_GNRC_IPV6_NIB_NUMOF                  (1)
+# define CONFIG_GNRC_IPV6_NIB_NUMOF                  (1 + IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES))
 # endif
 #endif
 #endif
@@ -186,6 +186,14 @@
 #define CONFIG_GNRC_IPV6_NIB_SLAAC                    1
 #endif
 
+/**
+ * @brief Use temporary addresses (rfc8981)
+ * @see [RFC 8981](https://www.rfc-editor.org/rfc/rfc8981.html)
+ */
+#ifndef CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES
+#define CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES 0
+#endif
+
 /**
  * @brief    handle Redirect Messages
  */

sys/include/net/gnrc/ipv6/nib/pl.h

@@ -90,6 +90,19 @@ int gnrc_ipv6_nib_pl_set(unsigned iface,
 void gnrc_ipv6_nib_pl_del(unsigned iface,
                           const ipv6_addr_t *pfx, unsigned pfx_len);
 
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES) || defined(DOXYGEN)
+/**
+ * @brief Check whether the prefix list has a prefix as specified
+ * @param[in] iface The interface @p pfx is expected to be on (0 for any).
+ * @param[in] pfx The prefix to check for.
+ * @param[in] pfx_len Length of @p pfx in bits.
+ * @return true if such prefix is present, false otherwise
+ */
+bool gnrc_ipv6_nib_pl_has_prefix(const unsigned int iface, const ipv6_addr_t *pfx,
+                                 const uint8_t pfx_len);
+
+#endif
+
 /**
  * @brief   Iterates over all prefix list entries in the NIB.
  *

sys/include/net/gnrc/netif/conf.h

@@ -102,6 +102,33 @@ extern "C" {
 #define GNRC_NETIF_IPV6_RTR_ADDR   (0)
 #endif
 
+/**
+ * @brief Maximum assumed number of valid (preferred or deprecated) temporary addresses.
+ * (see _nib-slaac.h)
+ *
+ * This value is not enforced but only used to increase
+ * the amount of configurable addresses, to make space for temporary addresses.
+ *
+ * Assuming continued use of the same prefix,
+ * the number of simultaneous temporary addresses
+ * can be expressed by the following (not considering REGEN_ADVANCE):
+ * @ref TEMP_VALID_LIFETIME / min_pref_lft=(@ref TEMP_PREFERRED_LIFETIME - @ref MAX_DESYNC_FACTOR)
+ * (Calculates the addresses that are generated within an address's lifetime.)
+ * -> floor(...) to only consider already generated addresses
+ * -> +1 to also account for the first address itself
+ *
+ * @see CONFIG_GNRC_IPV6_NIB_OFFL_NUMOF
+ *      May need to be increased; each temporary address has a /128 prefix
+ *      to manage its maximum total lifetimes.
+ */
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES) || defined(DOXYGEN)
+#ifndef MAX_TEMP_ADDRESSES
+#define MAX_TEMP_ADDRESSES (4)
+#endif
+#else
+#define MAX_TEMP_ADDRESSES (0)
+#endif
+
 /**
  * @brief   Maximum number of unicast and anycast addresses per interface
  *
@@ -110,11 +137,12 @@ extern "C" {
  *          addresses' solicited nodes multicast addresses.
  *
  * Default: 2 (1 link-local + 1 global address) + any additional address via
- * configuration protocol (e.g. DHCPv6 leases).
+ * configuration protocol (e.g. DHCPv6 leases) + temporary addresses.
  */
 #ifndef CONFIG_GNRC_NETIF_IPV6_ADDRS_NUMOF
 #define CONFIG_GNRC_NETIF_IPV6_ADDRS_NUMOF    (2 + \
-                                               DHCPV6_CLIENT_ADDRS_NUMOF)
+                                               DHCPV6_CLIENT_ADDRS_NUMOF + \
+                                               MAX_TEMP_ADDRESSES)
 #endif
 
 /**

sys/include/net/gnrc/netif/internal.h

@@ -130,6 +130,28 @@ void gnrc_netif_ipv6_addr_remove_internal(gnrc_netif_t *netif,
 int gnrc_netif_ipv6_addr_idx(gnrc_netif_t *netif,
                              const ipv6_addr_t *addr);
 
+/**
+ * @brief   Returns the index of the first addr
+ *          in gnrc_netif_t::ipv6_addrs of @p netif
+ *          where the first @p pfx_len bits match with @p pfx
+ *
+ * @pre `(netif != NULL) && (pfx != NULL)`
+ *
+ * Can be used to check if an address is assigned to an interface.
+ *
+ * @param[in] netif the network interface
+ * @param[in] pfx  the prefix to match
+ * @param[in] pfx_len the amount of bits to compare
+ *
+ * @note    Only available with @ref net_gnrc_ipv6 "gnrc_ipv6".
+ *
+ * @return  index of the first matching address
+ *          in gnrc_netif_t::ipv6_addrs of @p netif
+ * @return  -1, if no matching address found for @p netif
+ */
+int gnrc_netif_ipv6_addr_pfx_idx(gnrc_netif_t *netif,
+                                 const ipv6_addr_t *pfx, uint8_t pfx_len);
+
 /**
  * @brief   Gets state from address flags
  *
@@ -160,6 +182,24 @@ static inline uint8_t gnrc_netif_ipv6_addr_dad_trans(const gnrc_netif_t *netif,
     return netif->ipv6.addrs_flags[idx] & GNRC_NETIF_IPV6_ADDRS_FLAGS_STATE_TENTATIVE;
 }
 
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES) || defined(DOXYGEN)
+/**
+ * @brief   Gets number of address generation retries already performed for an address
+ *
+ * @param[in] netif the network interface
+ * @param[in] idx   index of the address (and its flags)
+ *
+ * @return  the number of address generation retries already
+ *          performed
+ */
+static inline uint8_t gnrc_netif_ipv6_addr_gen_retries(const gnrc_netif_t *netif,
+                                                     int idx)
+{
+    return (netif->ipv6.addrs_flags[idx] & GNRC_NETIF_IPV6_ADDRS_FLAGS_IDGEN_RETRIES)
+            >> GNRC_NETIF_IPV6_ADDRS_FLAGS_IDGEN_RETRIES_POS;
+}
+#endif
+
 /**
  * @brief   Returns the index of an address in gnrc_netif_t::ipv6_addrs of @p
  *          netif that matches @p addr best
@@ -201,9 +241,6 @@ int gnrc_netif_ipv6_addr_match(gnrc_netif_t *netif,
  * @todo Rule 6 from RFC 6724 is currently not implemented. Has to updated as
  *       soon as gnrc supports flow labels.
  *
- * @todo Rule 7 from RFC 6724 is currently not implemented. Has to updated as
- *       soon as gnrc supports temporary addresses.
- *
  * @return  The best source address for a packet addressed to @p dst
  * @return  NULL, if no matching address can be found on the interface.
  */
@@ -563,6 +600,17 @@ void gnrc_netif_init_6ln(gnrc_netif_t *netif);
  */
 void gnrc_netif_ipv6_init_mtu(gnrc_netif_t *netif);
 
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES) || defined(DOXYGEN)
+/**
+ * @brief Get DupAddrDetectTransmits
+ * @see https://datatracker.ietf.org/doc/html/rfc4862#section-5.1
+ * @return  DupAddrDetectTransmits
+ * @return  `-ENOTSUP`, when unimplemented for
+ *          gnrc_netif_t::device_type of @p netif
+*/
+int gnrc_netif_ipv6_dad_transmits(const gnrc_netif_t *netif);
+#endif
+
 /**
  * @brief   Converts a given hardware address to an IPv6 IID.
  *

sys/include/net/gnrc/netif/ipv6.h

@@ -68,6 +68,18 @@ extern "C" {
  * @brief   Address is an anycast address
  */
 #define GNRC_NETIF_IPV6_ADDRS_FLAGS_ANYCAST                (0x20U)
+
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES) || defined(DOXYGEN)
+/**
+ * @brief Number of address generation retries
+ * Used for temporary addresses, where the upper limit is defined by @ref TEMP_IDGEN_RETRIES
+ */
+#define GNRC_NETIF_IPV6_ADDRS_FLAGS_IDGEN_RETRIES          (0xC0U)
+/**
+ * @brief Shift position of address generation retries
+ */
+#define GNRC_NETIF_IPV6_ADDRS_FLAGS_IDGEN_RETRIES_POS      (6)
+#endif
 /** @} */
 
 /**

sys/net/gnrc/netif/gnrc_netif.c

@@ -46,6 +46,9 @@
 #include "net/gnrc/netif.h"
 #include "net/gnrc/netif/internal.h"
 #include "net/gnrc/tx_sync.h"
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES)
+#include "../network_layer/ipv6/nib/_nib-slaac.h"
+#endif
 
 #define ENABLE_DEBUG 0
 #include "debug.h"
@@ -502,6 +505,9 @@
 
 #if IS_USED(MODULE_GNRC_NETIF_IPV6)
 static int _addr_idx(const gnrc_netif_t *netif, const ipv6_addr_t *addr);
+static int _addr_pfx_idx(const gnrc_netif_t *netif,
+                                const ipv6_addr_t *pfx,
+                                uint8_t pfx_len);
 static int _group_idx(const gnrc_netif_t *netif, const ipv6_addr_t *addr);
 
 static char addr_str[IPV6_ADDR_MAX_STR_LEN];
@@ -689,6 +695,9 @@
 {
     bool remove_sol_nodes = true;
     ipv6_addr_t sol_nodes;
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES)
+    ipv6_addr_t addr_backup = *addr;
+#endif
 
     assert((netif != NULL) && (addr != NULL));
     ipv6_addr_set_solicited_nodes(&sol_nodes, addr);
@@ -713,6 +722,15 @@
         gnrc_netif_ipv6_group_leave_internal(netif, &sol_nodes);
     }
     gnrc_netif_release(netif);
+
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES)
+    // for temporary addresses (deleted on DAD failure or manually),
+    // also their prefix needs to be removed
+    gnrc_ipv6_nib_pl_del(netif->pid, &addr_backup, IPV6_ADDR_BIT_LEN);
+    // only expected to find a prefix if it's a temporary address.
+    // on prefix deletion, it won't find an address to delete
+    // this is fine, to avoid infinite loop
+#endif
 }
 
 int gnrc_netif_ipv6_addr_idx(gnrc_netif_t *netif,
@@ -730,6 +748,23 @@
     return idx;
 }
 
+int gnrc_netif_ipv6_addr_pfx_idx(gnrc_netif_t *netif,
+                                 const ipv6_addr_t *pfx, uint8_t pfx_len)
+{
+    int idx;
+
+    assert((netif != NULL) && (pfx != NULL));
+    DEBUG("gnrc_netif: get index of first address matching %s/%u"
+          " from interface %" PRIkernel_pid "\n",
+          ipv6_addr_to_str(addr_str, pfx, sizeof(addr_str)),
+          pfx_len,
+          netif->pid);
+    gnrc_netif_acquire(netif);
+    idx = _addr_pfx_idx(netif, pfx, pfx_len);
+    gnrc_netif_release(netif);
+    return idx;
+}
+
 int gnrc_netif_ipv6_addr_match(gnrc_netif_t *netif,
                                const ipv6_addr_t *addr)
 {
@@ -947,11 +982,35 @@
     return -1;
 }
 
+static int _pfx_idx(const gnrc_netif_t *netif, const ipv6_addr_t *pfx, uint8_t pfx_len, bool mcast)
+{
+    //same as function @ref _idx above, but with generalized condition
+    if (!ipv6_addr_is_unspecified(pfx)) {
+        const ipv6_addr_t *iplist = (mcast) ? netif->ipv6.groups :
+                                    netif->ipv6.addrs;
+        unsigned ipmax = (mcast) ? GNRC_NETIF_IPV6_GROUPS_NUMOF :
+                         CONFIG_GNRC_NETIF_IPV6_ADDRS_NUMOF;
+        for (unsigned i = 0; i < ipmax; i++) {
+            if (ipv6_addr_match_prefix(&iplist[i], pfx) >= pfx_len) {
+                return i;
+            }
+        }
+    }
+    return -1;
+}
+
 static inline int _addr_idx(const gnrc_netif_t *netif, const ipv6_addr_t *addr)
 {
     return _idx(netif, addr, false);
 }
 
+static inline int _addr_pfx_idx(const gnrc_netif_t *netif,
+                                const ipv6_addr_t *pfx,
+                                uint8_t pfx_len)
+{
+    return _pfx_idx(netif, pfx, pfx_len, false);
+}
+
 static inline int _group_idx(const gnrc_netif_t *netif, const ipv6_addr_t *addr)
 {
     return _idx(netif, addr, true);
@@ -1110,6 +1169,8 @@
 /* number of "points" assigned to an source address candidate in preferred
  * state */
 #define RULE_3_PTS          (1)
+/* number of "points" assigned to a temporary source address candidate */
+#define RULE_7_PTS          (1)
 
 /**
  * @brief   Caps the match at a source addresses prefix length
@@ -1234,10 +1295,13 @@
          * TODO: update as soon as gnrc supports flow labels
          */
 
-        /* Rule 7: Prefer temporary addresses.
-         * Temporary addresses are currently not supported by gnrc.
-         * TODO: update as soon as gnrc supports temporary addresses
-         */
+        /* Rule 7: Prefer temporary addresses. */
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES)
+        if (is_temporary_addr(netif, ptr)) {
+            DEBUG("winner for rule 7 found\n");
+            winner_set[i] += RULE_7_PTS;
+        }
+#endif
 
         if (winner_set[i] > max_pts) {
             idx = i;
@@ -2149,4 +2213,4 @@
         }
     }
 }
 /** @} */

sys/net/gnrc/netif/gnrc_netif_device_type.c

@@ -24,6 +24,7 @@
 #include "net/eui48.h"
 #include "net/gnrc/netif.h"
 #include "net/ieee802154.h"
+#include "net/sixlowpan/nd.h"
 #include "net/l2util.h"
 
 #if IS_USED(MODULE_GNRC_NETIF_IPV6)
@@ -219,6 +220,24 @@ void gnrc_netif_ipv6_init_mtu(gnrc_netif_t *netif)
     }
 }
 
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES)
+int gnrc_netif_ipv6_dad_transmits(const gnrc_netif_t *netif)
+{
+    switch (netif->device_type) {
+        #if defined(MODULE_NETDEV_IEEE802154)
+        case NETDEV_TYPE_IEEE802154:
+            return SIXLOWPAN_ND_REG_TRANSMIT_NUMOF;
+        #endif
+        #if defined(MODULE_NETDEV_ETH)
+        case NETDEV_TYPE_ETHERNET:
+            return NDP_DAD_TRANSMIT_NUMOF;
+        #endif
+        default:
+            return -ENOTSUP;
+    }
+}
+#endif
+
 int gnrc_netif_ipv6_iid_from_addr(const gnrc_netif_t *netif,
                                   const uint8_t *addr, size_t addr_len,
                                   eui64_t *iid)

sys/net/gnrc/network_layer/ipv6/gnrc_ipv6.c

@@ -237,6 +237,9 @@ static void *_event_loop(void *args)
             case GNRC_IPV6_NIB_ADDR_REG_TIMEOUT:
             case GNRC_IPV6_NIB_ABR_TIMEOUT:
             case GNRC_IPV6_NIB_PFX_TIMEOUT:
+#if IS_ACTIVE(CONFIG_GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES)
+            case GNRC_IPV6_NIB_REGEN_TEMP_ADDR:
+#endif
             case GNRC_IPV6_NIB_RTR_TIMEOUT:
             case GNRC_IPV6_NIB_RECALC_REACH_TIME:
             case GNRC_IPV6_NIB_REREG_ADDRESS:

sys/net/gnrc/network_layer/ipv6/nib/Kconfig

@@ -38,6 +38,10 @@ config GNRC_IPV6_NIB_SLAAC
     default n if USEMODULE_GNRC_IPV6_NIB_6LR || USEMODULE_GNRC_IPV6_NIB_6LN
     default y
 
+config GNRC_IPV6_NIB_SLAAC_TEMPORARY_ADDRESSES
+    bool "Use temporary addresses (rfc8981)"
+    depends on GNRC_IPV6_NIB_SLAAC
+
 config GNRC_IPV6_NIB_QUEUE_PKT
     bool "Use packet queue with address resolution"
     default n if USEMODULE_GNRC_IPV6_NIB_6LN || GNRC_IPV6_NIB_6LN