libosmo-gtlv: add TLIV capability

During code review, it was indicated that some TLV protocols that we
will likely deal with in the near future also employ an I, and instance
value of a tag. Add TLIV support.

A usage example for a manually implemented TLIV structure is found in
tests/libosmo-gtlv/gtlv_test.c.

A usage example for a generated TLIV protocol is found in
tests/libosmo-gtlv/test_tliv/.

Related: SYS#5599
Change-Id: I0a076e54dfba6038cc779cb7c8f3967d212226aa

1 files changed, 68 insertions, 0 deletions

diff --git a/tests/libosmo-gtlv/test_tliv/myproto_ies_custom.c b/tests/libosmo-gtlv/test_tliv/myproto_ies_custom.c
new file mode 100644
index 0000000..54164ce
--- /dev/null
+++ b/tests/libosmo-gtlv/test_tliv/myproto_ies_custom.c
@@ -0,0 +1,68 @@
+/* Example for defining custom IES for gtlv_gen. */
+/*
+ * (C) 2021-2022 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <errno.h>
+#include <inttypes.h>
+
+#include <osmocom/core/bits.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/gtlv/gtlv.h>
+
+#include <myproto_ies_custom.h>
+
+int myproto_dec_bar(void *decoded_struct, void *decode_to, const struct osmo_gtlv_load *gtlv)
+{
+	struct myproto_ie_bar *bar = decode_to;
+	if (gtlv->len < 2)
+		return -EINVAL;
+	*bar = (struct myproto_ie_bar){
+		.a = gtlv->val[0],
+		.b = (gtlv->val[1] == 1),
+	};
+	return 0;
+}
+
+int myproto_enc_bar(struct osmo_gtlv_put *gtlv, void *decoded_struct, void *encode_from)
+{
+	struct myproto_ie_bar *bar = encode_from;
+	msgb_put_u8(gtlv->dst, bar->a);
+	msgb_put_u8(gtlv->dst, bar->b ? 1 : 0);
+	return 0;
+}
+
+int myproto_enc_to_str_bar(char *buf, size_t buflen, void *encode_from)
+{
+	struct myproto_ie_bar *bar = encode_from;
+	return snprintf(buf, buflen, "%d,%s", bar->a, bar->b ? "true" : "false");
+}
+
+const struct value_string myproto_msg_type_names[] = {
+	{ MYPROTO_MSGT_MOO, "MOO" },
+	{}
+};
+
+const struct value_string myproto_iei_names[] = {
+	{ MYPROTO_IEI_BAR, "BAR" },
+	{}
+};