net: IPv6 address utility funcs for network interface

Added more functions to get proper IPv6 address from
a given network interface.

Change-Id: I5aecdb35eb549a0781949134ab4821dcb8ce9e7b
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

include/net/yaip/net_if.h

@@ -268,6 +268,48 @@ struct net_if_addr *net_if_ipv4_addr_add(struct net_if *iface,
 					 enum net_addr_type addr_type,
 					 uint32_t vlifetime);
 
+/**
+ * @brief Get IPv6 hop limit specified for a given interface
+ * @param iface Network interface
+ * @return Hop limit
+ */
+static inline uint8_t net_if_ipv6_get_hop_limit(struct net_if *iface)
+{
+#if defined(CONFIG_NET_IPV6)
+	return iface->hop_limit;
+#else
+	return 0;
+#endif
+}
+
+/**
+ * @brief Get a IPv6 source address that should be used when sending
+ * network data to destination.
+ * @param iface Interface that was used when packet was received.
+ * If the interface is not known, then NULL can be given.
+ * @param dst IPv6 destination address
+ * @return Pointer to IPv6 address to use, NULL if no IPv6 address
+ * could be found.
+ */
+struct in6_addr *net_if_ipv6_select_src_addr(struct net_if *iface,
+					     struct in6_addr *dst);
+
+/**
+ * @brief Return IPv6 any address (all zeros, ::)
+ * @return IPv6 any address with all bits set to zero.
+ */
+struct in6_addr *net_if_ipv6_unspecified_addr(void);
+
+/**
+ * @brief Get a IPv6 link local address in a given state.
+ * @param iface Interface to use. Must be a valid pointer to an interface.
+ * @param addr_state IPv6 address state (preferred, tentative, deprecated)
+ * @return Pointer to link local IPv6 address, NULL if no proper IPv6 address
+ * could be found.
+ */
+struct in6_addr *net_if_ipv6_get_ll(struct net_if *iface,
+				    enum net_addr_state addr_state);
+
 struct net_if_api {
 	void (*init)(struct net_if *iface);
 	int (*send)(struct net_if *iface, struct net_buf *buf);

include/net/yaip/net_ip.h

@@ -151,6 +151,7 @@ static inline char *net_addr_type2str(enum net_addr_type type)
 
 /** What is the current state of the network address */
 enum net_addr_state {
+	NET_ADDR_ANY_STATE = -1,
 	NET_ADDR_TENTATIVE = 0,
 	NET_ADDR_PREFERRED,
 	NET_ADDR_DEPRECATED,
@@ -235,6 +236,37 @@ static inline bool net_is_my_ipv4_addr(struct in_addr *addr)
 	return net_if_ipv4_addr_lookup(addr) != NULL;
 }
 
+/** @def net_ipaddr_copy
+ *  @brief Copy an IPv4 or IPv6 address
+ *
+ *  @param dest Destination IP address.
+ *  @param src Source IP address.
+ *
+ *  @return Destination address.
+ */
+#define net_ipaddr_copy(dest, src) ((*dest) = (*src))
+
+/** @brief Check if the given IPv6 address is a link local address.
+ *
+ * @return True if it is, false otherwise.
+ */
+static inline bool net_is_ipv6_ll_addr(struct in6_addr *addr)
+{
+	return ((addr->s6_addr[0]) == 0xFE) &&
+		((addr->s6_addr[1]) == 0x80);
+}
+
+struct in6_addr *net_if_ipv6_unspecified_addr(void);
+
+/** @brief Return pointer to any (all bits zeros) IPv6 address.
+ *
+ * @return Any IPv6 address.
+ */
+static inline struct in6_addr *net_ipv6_unspecified_address(void)
+{
+	return net_if_ipv6_unspecified_addr();
+}
+
 #ifdef __cplusplus
 }
 #endif

net/yaip/net_if.c

@@ -189,6 +189,156 @@ struct net_if_mcast_addr *net_if_ipv6_maddr_lookup(struct in6_addr *maddr)
 	return NULL;
 }
 
+struct in6_addr *net_if_ipv6_unspecified_addr(void)
+{
+#if defined(CONFIG_NET_IPV6)
+	static struct in6_addr addr = IN6ADDR_ANY_INIT;
+
+	return &addr;
+#else
+	return NULL;
+#endif
+}
+
+struct in6_addr *net_if_ipv6_get_ll(struct net_if *iface,
+				    enum net_addr_state addr_state)
+{
+	int i;
+
+	for (i = 0; i < NET_IF_MAX_IPV6_ADDR; i++) {
+		if (!iface->ipv6.unicast[i].is_used ||
+		    (addr_state != NET_ADDR_ANY_STATE &&
+		     iface->ipv6.unicast[i].addr_state != addr_state) ||
+		    iface->ipv6.unicast[i].address.family != AF_INET6) {
+			continue;
+		}
+		if (net_is_ipv6_ll_addr(&iface->ipv6.unicast[i].address.in6_addr)) {
+			return &iface->ipv6.unicast[i].address.in6_addr;
+		}
+	}
+
+	return NULL;
+}
+
+static inline uint8_t get_length(struct in6_addr *src, struct in6_addr *dst)
+{
+	uint8_t j, k, xor;
+	uint8_t len = 0;
+
+	for (j = 0; j < 16; j++) {
+		if (src->s6_addr[j] == dst->s6_addr[j]) {
+			len += 8;
+		} else {
+			xor = src->s6_addr[j] ^ dst->s6_addr[j];
+			for (k = 0; k < 8; k++) {
+				if (!(xor & 0x80)) {
+					len++;
+					xor <<= 1;
+				} else {
+					break;
+				}
+			}
+			break;
+		}
+	}
+
+	return len;
+}
+
+static inline bool is_proper_ipv6_address(struct net_if_addr *addr)
+{
+	if (addr->is_used && addr->addr_state == NET_ADDR_PREFERRED &&
+	    addr->address.family == AF_INET6 &&
+	    !net_is_ipv6_ll_addr(&addr->address.in6_addr)) {
+		return true;
+	}
+
+	return false;
+}
+
+static inline struct in6_addr *net_if_ipv6_get_best_match(struct net_if *iface,
+							  struct in6_addr *dst,
+							  uint8_t *best_so_far)
+{
+#if defined(CONFIG_NET_IPV6)
+	struct in6_addr *src = NULL;
+	uint8_t i, len;
+
+	for (i = 0; i < NET_IF_MAX_IPV6_ADDR; i++) {
+		if (!is_proper_ipv6_address(&iface->ipv6.unicast[i])) {
+			continue;
+		}
+
+		len = get_length(dst,
+				 &iface->ipv6.unicast[i].address.in6_addr);
+		if (len >= *best_so_far) {
+			*best_so_far = len;
+			src = &iface->ipv6.unicast[i].address.in6_addr;
+		}
+	}
+
+	return src;
+#else
+	return NULL;
+#endif
+}
+
+struct in6_addr *net_if_ipv6_select_src_addr(struct net_if *dst_iface,
+					     struct in6_addr *dst)
+{
+#if defined(CONFIG_NET_IPV6)
+	struct in6_addr *src = NULL;
+	uint8_t best_match = 0;
+	struct net_if *iface;
+
+	if (!net_is_ipv6_ll_addr(dst) && !net_is_ipv6_addr_mcast(dst)) {
+
+		for (iface = __net_if_start;
+		     !dst_iface && iface != __net_if_end;
+		     iface++) {
+			struct in6_addr *addr;
+
+			addr = net_if_ipv6_get_best_match(iface, dst,
+							  &best_match);
+			if (addr) {
+				src = addr;
+			}
+		}
+
+		/* If caller has supplied interface, then use that */
+		if (dst_iface) {
+			src = net_if_ipv6_get_best_match(dst_iface, dst,
+							 &best_match);
+		}
+
+	} else {
+		for (iface = __net_if_start;
+		     !dst_iface && iface != __net_if_end;
+		     iface++) {
+			struct in6_addr *addr;
+
+			addr = net_if_ipv6_get_ll(iface, NET_ADDR_PREFERRED);
+			if (addr) {
+				src = addr;
+				break;
+			}
+		}
+
+		if (dst_iface) {
+			src = net_if_ipv6_get_ll(dst_iface, NET_ADDR_PREFERRED);
+		}
+	}
+
+	if (!src) {
+		return net_if_ipv6_unspecified_addr();
+	}
+
+	return src;
+#else
+	return NULL;
+#endif
+}
+
 struct net_if_addr *net_if_ipv4_addr_lookup(struct in_addr *addr)
 {
 	struct net_if *iface;