rpcd-mod-luci: Return array of addresses in getHostHints

Update luci-rpc's getHostHints method to return two string arrays for
each host, `ipaddrs` and `ip6addrs`, each containing the host's IPv4
and IPv6 addresses, respectively.  Each array is sorted by a priority
derived from the source from which the address was discovered.  The
current address sources and their priority is as follows (a
higher (larger) priority is listed first):

    - neighbor table entries: 10
    - /etc/ethers entries:    50
    - DHCP leasefile:        100
    - RRDNS queries:         100
    - getifaddrs():          200
    - UCI static leases:     200

The existing `ipv4` and `ipv6` string fields for each host in
`getHostHints` has been removed.  Downstream users of getHostHints
still need to be updated.

Fixes: #4838
Signed-off-by: Niels Widger <niels@qacafe.com>
[squash commits, reformat fixes tag]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
(cherry picked from commit a5195e7825)

libs/rpcd-mod-luci/src/luci.c

@@ -1135,10 +1135,48 @@ rpc_luci_get_wireless_devices(struct ubus_context *ctx,
 struct host_hint {
 	struct avl_node avl;
 	char *hostname;
-	struct in_addr ip;
+	struct avl_tree ipaddrs;
-	struct in6_addr ip6;
+	struct avl_tree ip6addrs;
 };
 
+/* used to ignore priority with avl_find_element */
+#define HOST_HINT_PRIO_IGNORE        -1
+
+/* higher (larger) priority addresses are listed first */
+#define HOST_HINT_PRIO_NL            10 /* neighbor table */
+#define HOST_HINT_PRIO_ETHER         50 /* /etc/ethers */
+#define HOST_HINT_PRIO_LEASEFILE    100 /* dhcp leasefile */
+#define HOST_HINT_PRIO_RRDNS        100 /* rrdns */
+#define HOST_HINT_PRIO_IFADDRS      200 /* getifaddrs() */
+#define HOST_HINT_PRIO_STATIC_LEASE 200 /* uci static leases */
+
+struct host_hint_addr {
+	struct avl_node avl;
+	int af;
+	int prio;
+	union {
+		struct in_addr in;
+		struct in6_addr in6;
+	} addr;
+};
+
+static int
+host_hint_addr_avl_cmp(const void *k1, const void *k2, void *ptr)
+{
+	struct host_hint_addr *a1 = (struct host_hint_addr *)k1;
+	struct host_hint_addr *a2 = (struct host_hint_addr *)k2;
+
+	if (a1->prio != a2->prio &&
+	    a1->prio != HOST_HINT_PRIO_IGNORE &&
+	    a2->prio != HOST_HINT_PRIO_IGNORE)
+		return a1->prio < a2->prio ? 1 : -1;
+
+	if (a1->af != a2->af)
+		return a1->af < a2->af ? -1 : 1;
+
+	return memcmp(&a1->addr, &a2->addr, sizeof(a1->addr));
+}
+
 static int
 nl_cb_done(struct nl_msg *msg, void *arg)
 {
@@ -1174,12 +1212,69 @@ rpc_luci_get_host_hint(struct reply_context *rctx, struct ether_addr *ea)
 			return NULL;
 
 		hint->avl.key = strcpy(p, mac);
+		avl_init(&hint->ipaddrs, host_hint_addr_avl_cmp, false, NULL);
+		avl_init(&hint->ip6addrs, host_hint_addr_avl_cmp, false, NULL);
 		avl_insert(&rctx->avl, &hint->avl);
 	}
 
 	return hint;
 }
 
+static void
+rpc_luci_add_host_hint_addr(struct host_hint *hint, int af, int prio, void *addr)
+{
+	struct host_hint_addr e, *a;
+	struct avl_tree *addrs = af == AF_INET ? &hint->ipaddrs : &hint->ip6addrs;
+
+	if (!addr)
+		return;
+
+	memset(&e, 0, sizeof(e));
+	e.af = af;
+	/* ignore prio when comparing against existing addresses */
+	e.prio = HOST_HINT_PRIO_IGNORE;
+
+	if (af == AF_INET)
+		memcpy(&e.addr.in, (struct in_addr *)addr, sizeof(e.addr.in));
+	else
+		memcpy(&e.addr.in6, (struct in6_addr *)addr, sizeof(e.addr.in6));
+
+	a = avl_find_element(addrs, &e, a, avl);
+
+	if (a) {
+		/* update prio of existing address if higher */
+		if (prio <= a->prio)
+			return;
+
+		avl_delete(addrs, &a->avl);
+		a->prio = prio;
+		avl_insert(addrs, &a->avl);
+		return;
+	}
+
+	a = calloc(1, sizeof(*a));
+
+	if (!a)
+		return;
+
+	memcpy(a, &e, sizeof(*a));
+	a->prio = prio;
+	a->avl.key = a;
+	avl_insert(addrs, &a->avl);
+}
+
+static void
+rpc_luci_add_host_hint_ipaddr(struct host_hint *hint, int prio, struct in_addr *addr)
+{
+	return rpc_luci_add_host_hint_addr(hint, AF_INET, prio, (void *)addr);
+}
+
+static void
+rpc_luci_add_host_hint_ip6addr(struct host_hint *hint, int prio, struct in6_addr *addr)
+{
+	return rpc_luci_add_host_hint_addr(hint, AF_INET6, prio, (void *)addr);
+}
+
 static int nl_cb_dump_neigh(struct nl_msg *msg, void *arg)
 {
 	struct reply_context *rctx = arg;
@@ -1213,9 +1308,9 @@ static int nl_cb_dump_neigh(struct nl_msg *msg, void *arg)
 		return NL_SKIP;
 
 	if (nd->ndm_family == AF_INET)
-		hint->ip = *(struct in_addr *)dst;
+		rpc_luci_add_host_hint_ipaddr(hint, HOST_HINT_PRIO_NL, (struct in_addr *)dst);
 	else
-		hint->ip6 = *(struct in6_addr *)dst;
+		rpc_luci_add_host_hint_ip6addr(hint, HOST_HINT_PRIO_NL, (struct in6_addr *)dst);
 
 	return NL_SKIP;
 }
@@ -1298,8 +1393,7 @@ rpc_luci_get_host_hints_ether(struct reply_context *rctx)
 			continue;
 
 		if (inet_pton(AF_INET, p, &in) == 1) {
-			if (hint->ip.s_addr == 0)
+			rpc_luci_add_host_hint_ipaddr(hint, HOST_HINT_PRIO_ETHER, &in);
-				hint->ip = in;
 		}
 		else if (*p && !hint->hostname) {
 			hint->hostname = strdup(p);
@@ -1315,13 +1409,13 @@ rpc_luci_get_host_hints_uci(struct reply_context *rctx)
 	struct uci_ptr ptr = { .package = "dhcp" };
 	struct uci_context *uci = NULL;
 	struct uci_package *pkg = NULL;
-	struct in6_addr empty = {};
 	struct lease_entry *lease;
 	struct host_hint *hint;
 	struct uci_element *e, *l;
 	struct uci_section *s;
 	struct in_addr in;
 	char *p, *n;
+	int i;
 
 	uci = uci_alloc_context();
 
@@ -1379,8 +1473,8 @@ rpc_luci_get_host_hints_uci(struct reply_context *rctx)
 				if (!hint)
 					continue;
 
-				if (hint->ip.s_addr == 0 && in.s_addr != 0)
+				if (in.s_addr != 0)
-					hint->ip = in;
+					rpc_luci_add_host_hint_ipaddr(hint, HOST_HINT_PRIO_STATIC_LEASE, &in);
 
 				if (n && !hint->hostname)
 					hint->hostname = strdup(n);
@@ -1393,8 +1487,8 @@ rpc_luci_get_host_hints_uci(struct reply_context *rctx)
 				if (!hint)
 					continue;
 
-				if (hint->ip.s_addr == 0 && in.s_addr != 0)
+				if (in.s_addr != 0)
-					hint->ip = in;
+					rpc_luci_add_host_hint_ipaddr(hint, HOST_HINT_PRIO_STATIC_LEASE, &in);
 
 				if (n && !hint->hostname)
 					hint->hostname = strdup(n);
@@ -1410,11 +1504,12 @@ rpc_luci_get_host_hints_uci(struct reply_context *rctx)
 		if (!hint)
 			continue;
 
-		if (lease->af == AF_INET && lease->n_addr && hint->ip.s_addr == 0)
+		for (i = 0; i < lease->n_addr; i++) {
-			hint->ip = lease->addr[0].in;
+			if (lease->af == AF_INET)
-		else if (lease->af == AF_INET6 && lease->n_addr &&
+				rpc_luci_add_host_hint_ipaddr(hint, HOST_HINT_PRIO_LEASEFILE, &lease->addr[i].in);
-		         !memcmp(&hint->ip6, &empty, sizeof(empty)))
+			else if (lease->af == AF_INET6)
-			hint->ip6 = lease->addr[0].in6;
+				rpc_luci_add_host_hint_ip6addr(hint, HOST_HINT_PRIO_LEASEFILE, &lease->addr[i].in6);
+		}
 
 		if (lease->hostname && !hint->hostname)
 			hint->hostname = strdup(lease->hostname);
@@ -1493,12 +1588,11 @@ rpc_luci_get_host_hints_ifaddrs(struct reply_context *rctx)
 			hint = rpc_luci_get_host_hint(rctx, &device->ea);
 
 			if (hint) {
-				if (hint->ip.s_addr == 0 && device->in.s_addr != 0)
+				if (device->in.s_addr != 0)
-					hint->ip = device->in;
+					rpc_luci_add_host_hint_ipaddr(hint, HOST_HINT_PRIO_IFADDRS, &device->in);
 
-				if (memcmp(&hint->ip6, &empty_in6, sizeof(empty_in6)) == 0 &&
+				if (memcmp(&device->in6, &empty_in6, sizeof(empty_in6)) != 0)
-				    memcmp(&device->in6, &empty_in6, sizeof(empty_in6)) != 0)
+					rpc_luci_add_host_hint_ip6addr(hint, HOST_HINT_PRIO_IFADDRS, &device->in6);
-					hint->ip6 = device->in6;
 			}
 		}
 
@@ -1527,7 +1621,8 @@ rpc_luci_get_host_hints_rrdns_cb(struct ubus_request *req, int type,
 
 			if (inet_pton(AF_INET6, blobmsg_name(cur), &in6) == 1) {
 				avl_for_each_element(&rctx->avl, hint, avl) {
-					if (!memcmp(&hint->ip6, &in6, sizeof(in6))) {
+					rpc_luci_add_host_hint_ip6addr(hint, HOST_HINT_PRIO_RRDNS, &in6);
+					if (!avl_is_empty(&hint->ip6addrs)) {
 						if (hint->hostname)
 							free(hint->hostname);
 
@@ -1538,7 +1633,8 @@ rpc_luci_get_host_hints_rrdns_cb(struct ubus_request *req, int type,
 			}
 			else if (inet_pton(AF_INET, blobmsg_name(cur), &in) == 1) {
 				avl_for_each_element(&rctx->avl, hint, avl) {
-					if (!memcmp(&hint->ip, &in, sizeof(in))) {
+					rpc_luci_add_host_hint_ipaddr(hint, HOST_HINT_PRIO_RRDNS, &in);
+					if (!avl_is_empty(&hint->ipaddrs)) {
 						if (hint->hostname)
 							free(hint->hostname);
 
@@ -1560,6 +1656,7 @@ rpc_luci_get_host_hints_rrdns(struct reply_context *rctx)
 	char buf[INET6_ADDRSTRLEN];
 	struct blob_buf req = {};
 	struct host_hint *hint;
+	struct host_hint_addr *addr;
 	int n = 0;
 	void *a;
 
@@ -1568,17 +1665,21 @@ rpc_luci_get_host_hints_rrdns(struct reply_context *rctx)
 	a = blobmsg_open_array(&req, "addrs");
 
 	avl_for_each_element(&rctx->avl, hint, avl) {
-		if (hint->ip.s_addr != 0) {
+		avl_for_each_element(&hint->ipaddrs, addr, avl) {
-			inet_ntop(AF_INET, &hint->ip, buf, sizeof(buf));
+			if (addr->addr.in.s_addr != 0) {
+				inet_ntop(AF_INET, &addr->addr.in, buf, sizeof(buf));
 				blobmsg_add_string(&req, NULL, buf);
 				n++;
 			}
-		else if (memcmp(&hint->ip6, &empty_in6, sizeof(empty_in6))) {
+		}
-			inet_ntop(AF_INET6, &hint->ip6, buf, sizeof(buf));
+		avl_for_each_element(&hint->ip6addrs, addr, avl) {
+			if (memcmp(&addr->addr.in6, &empty_in6, sizeof(empty_in6))) {
+				inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf));
 				blobmsg_add_string(&req, NULL, buf);
 				n++;
 			}
 		}
+	}
 
 	blobmsg_close_array(&req, a);
 
@@ -1601,24 +1702,40 @@ static int
 rpc_luci_get_host_hints_finish(struct reply_context *rctx)
 {
 	struct host_hint *hint, *nexthint;
+	struct host_hint_addr *addr, *nextaddr;
 	char buf[INET6_ADDRSTRLEN];
 	struct in6_addr in6 = {};
-	struct in_addr in = {};
+	void *o, *a;
-	void *o;
 
 	avl_remove_all_elements(&rctx->avl, hint, avl, nexthint) {
 		o = blobmsg_open_table(&rctx->blob, hint->avl.key);
 
-		if (memcmp(&hint->ip, &in, sizeof(in))) {
+		a = blobmsg_open_array(&rctx->blob, "ipaddrs");
-			inet_ntop(AF_INET, &hint->ip, buf, sizeof(buf));
+
-			blobmsg_add_string(&rctx->blob, "ipv4", buf);
+		avl_remove_all_elements(&hint->ipaddrs, addr, avl, nextaddr) {
+			if (addr->addr.in.s_addr != 0) {
+				inet_ntop(AF_INET, &addr->addr.in, buf, sizeof(buf));
+				blobmsg_add_string(&rctx->blob, NULL, buf);
 			}
 
-		if (memcmp(&hint->ip6, &in6, sizeof(in6))) {
+			free(addr);
-			inet_ntop(AF_INET6, &hint->ip6, buf, sizeof(buf));
-			blobmsg_add_string(&rctx->blob, "ipv6", buf);
 		}
 
+		blobmsg_close_array(&rctx->blob, a);
+
+		a = blobmsg_open_array(&rctx->blob, "ip6addrs");
+
+		avl_remove_all_elements(&hint->ip6addrs, addr, avl, nextaddr) {
+			if (memcmp(&addr->addr.in6, &in6, sizeof(in6))) {
+				inet_ntop(AF_INET6, &addr->addr.in6, buf, sizeof(buf));
+				blobmsg_add_string(&rctx->blob, NULL, buf);
+			}
+
+			free(addr);
+		}
+
+		blobmsg_close_array(&rctx->blob, a);
+
 		if (hint->hostname)
 			blobmsg_add_string(&rctx->blob, "name", hint->hostname);