Initial work on ACLs

acls.go

@@ -0,0 +1,30 @@
+package headscale
+
+import (
+	"io"
+	"os"
+
+	"github.com/tailscale/hujson"
+)
+
+const errorInvalidPolicy = Error("invalid policy")
+
+func (h *Headscale) ParsePolicy(path string) (*ACLPolicy, error) {
+	policyFile, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer policyFile.Close()
+
+	var policy ACLPolicy
+	b, err := io.ReadAll(policyFile)
+	if err != nil {
+		return nil, err
+	}
+	err = hujson.Unmarshal(b, &policy)
+	if policy.IsZero() {
+		return nil, errorInvalidPolicy
+	}
+
+	return &policy, err
+}