Feat rego default policy (#700)

Converts rules to Rego policies and allow users to write raw policies to set up connectivity and firewall on the clients.

management/server/rego/default_policy.rego

@@ -0,0 +1,9 @@
+package netbird
+
+all[rule] {
+	is_peer_in_any_group([{{range $i, $e := .All}}{{if $i}},{{end}}"{{$e}}"{{end}}])
+	rule := array.concat(
+		rules_from_groups([{{range $i, $e := .Destination}}{{if $i}},{{end}}"{{$e}}"{{end}}], "dst", "accept", ""),
+		rules_from_groups([{{range $i, $e := .Source}}{{if $i}},{{end}}"{{$e}}"{{end}}], "src", "accept", ""),
+	)[_]
+}

management/server/rego/default_policy_module.rego

@@ -0,0 +1,40 @@
+package netbird
+
+import future.keywords.if
+import future.keywords.in
+import future.keywords.contains
+
+# get_rule builds a netbird rule object from given parameters
+get_rule(peer_id, direction, action, port) := rule if {
+    peer := input.peers[_]
+    peer.ID == peer_id
+    rule := {
+        "ID": peer.ID,
+        "IP": peer.IP,
+        "Direction": direction,
+        "Action": action,
+        "Port": port,
+    }
+}
+
+# peers_from_group returns a list of peer ids for a given group id
+peers_from_group(group_id) := peers if {
+	group := input.groups[_]
+	group.ID == group_id
+	peers := [peer | peer := group.Peers[_]]
+}
+
+# netbird_rules_from_groups returns a list of netbird rules for a given list of group names
+rules_from_groups(groups, direction, action, port) := rules if {
+	group_id := groups[_]
+	rules := [get_rule(peer, direction, action, port) | peer := peers_from_group(group_id)[_]]
+}
+
+# is_peer_in_any_group checks that input peer present at least in one group
+is_peer_in_any_group(groups) := count([group_id]) > 0 if {
+	group_id := groups[_]
+	group := input.groups[_]
+	group.ID == group_id
+	peer := group.Peers[_]
+	peer == input.peer_id
+}