1 files changed, 34 insertions, 0 deletions
diff --git a/src/libsystemd-network/ndisc-protocol.c b/src/libsystemd-network/ndisc-protocol.c
new file mode 100644
index 0000000..fae4a58
--- /dev/null
+++ b/src/libsystemd-network/ndisc-protocol.c
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "ndisc-protocol.h"
+
+static const uint8_t prefix_length_code_to_prefix_length[_PREFIX_LENGTH_CODE_MAX] = {
+        [PREFIX_LENGTH_CODE_96] = 96,
+        [PREFIX_LENGTH_CODE_64] = 64,
+        [PREFIX_LENGTH_CODE_56] = 56,
+        [PREFIX_LENGTH_CODE_48] = 48,
+        [PREFIX_LENGTH_CODE_40] = 40,
+        [PREFIX_LENGTH_CODE_32] = 32,
+};
+
+int pref64_plc_to_prefix_length(uint16_t plc, uint8_t *ret) {
+        plc &= PREF64_PLC_MASK;
+        if (plc >= _PREFIX_LENGTH_CODE_MAX)
+                return -EINVAL;
+
+        if (ret)
+                *ret = prefix_length_code_to_prefix_length[plc];
+        return 0;
+}
+
+int pref64_prefix_length_to_plc(uint8_t prefixlen, uint8_t *ret) {
+        assert(ret);
+
+        for (size_t i = 0; i < ELEMENTSOF(prefix_length_code_to_prefix_length); i++)
+                if (prefix_length_code_to_prefix_length[i] == prefixlen) {
+                        *ret = i;
+                        return 0;
+                }
+
+        return -EINVAL;
+}