net: if: Add ASSERT in net_if_ipv4/6_select_src_addr

Add an assert for the destination address provided to find the best
source address.

(cherry picked from commit cb4fb76)

Original-Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>
GitOrigin-RevId: cb4fb76
Change-Id: Ib7b22f0c6ed734c838fa27474f4931514a63c80a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/4894342
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Tested-by: Al Semjonovs <asemjonovs@google.com>
Reviewed-by: Al Semjonovs <asemjonovs@google.com>
Commit-Queue: Al Semjonovs <asemjonovs@google.com>

subsys/net/ip/net_if.c

@@ -2864,6 +2864,8 @@ const struct in6_addr *net_if_ipv6_select_src_addr(struct net_if *dst_iface,
 	const struct in6_addr *src = NULL;
 	uint8_t best_match = 0U;
 
+	NET_ASSERT(dst);
+
 	if (!net_ipv6_is_ll_addr(dst) && !net_ipv6_is_addr_mcast_link(dst)) {
 		/* If caller has supplied interface, then use that */
 		if (dst_iface) {
@@ -3405,6 +3407,8 @@ const struct in_addr *net_if_ipv4_select_src_addr(struct net_if *dst_iface,
 	const struct in_addr *src = NULL;
 	uint8_t best_match = 0U;
 
+	NET_ASSERT(dst);
+
 	if (!net_ipv4_is_ll_addr(dst)) {
 
 		/* If caller has supplied interface, then use that */