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, 217 insertions, 0 deletions

diff --git a/tests/libosmo-gtlv/test_tliv/tliv_test.c b/tests/libosmo-gtlv/test_tliv/tliv_test.c
new file mode 100644
index 0000000..fd4e310
--- /dev/null
+++ b/tests/libosmo-gtlv/test_tliv/tliv_test.c
@@ -0,0 +1,217 @@
+/*
+ * (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 <stdio.h>
+#include <errno.h>
+
+#include <osmocom/core/application.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/msgb.h>
+
+#include <osmocom/gtlv/gtlv.h>
+
+#include <myproto_ies_auto.h>
+
+struct myproto_msg {
+	enum myproto_msg_type type;
+	union myproto_ies ies;
+};
+
+static void err_cb(void *data, void *decoded_struct, const char *file, int line, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	//printf("ERR: %s:%d ", file, line);
+	printf("ERR: ");
+	vprintf(fmt, args);
+	va_end(args);
+}
+
+static int myproto_msg_enc(struct msgb *dst, const struct myproto_msg *msg, const struct osmo_gtlv_cfg *cfg)
+{
+	struct osmo_gtlv_put gtlv = {
+		.cfg = cfg,
+		.dst = dst,
+	};
+
+	msgb_put_u8(gtlv.dst, msg->type);
+	return myproto_ies_encode(&gtlv, (void *)&msg->ies, msg->type, err_cb, NULL, myproto_iei_names);
+}
+
+static int myproto_msg_dec(struct myproto_msg *msg, const uint8_t *data, size_t data_len,
+			   const struct osmo_gtlv_cfg *cfg, bool ordered)
+{
+	struct osmo_gtlv_load gtlv;
+	if (data_len < 1)
+		return -EINVAL;
+	msg->type = data[0];
+	gtlv = (struct osmo_gtlv_load){
+		.cfg = cfg,
+		.src = { data + 1, data_len - 1 },
+	};
+	return myproto_ies_decode(&msg->ies, &gtlv, ordered, msg->type, err_cb, NULL, myproto_iei_names);
+}
+
+void *ctx;
+
+struct myproto_msg tests[] = {
+	{
+		MYPROTO_MSGT_MOO,
+		{
+			.moo = {
+				.bar_alpha = { 23, true },
+				.bar_gamma = { 42, false },
+			},
+		},
+	},
+	{
+		MYPROTO_MSGT_MOO,
+		{
+			.moo = {
+				.bar_alpha = { 11, true },
+				.bar_beta_present = true,
+				.bar_beta = { 22, false },
+				.bar_gamma = { 33, true },
+			},
+		},
+	},
+};
+
+int myproto_msg_to_str_buf(char *buf, size_t buflen, const struct myproto_msg *m)
+{
+	struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+	OSMO_STRBUF_PRINTF(sb, "%s={", get_value_string(myproto_msg_type_names, m->type));
+	OSMO_STRBUF_APPEND(sb, osmo_gtlvs_encode_to_str_buf, &m->ies, 0, myproto_get_msg_coding(m->type),
+			   myproto_iei_names);
+	OSMO_STRBUF_PRINTF(sb, " }");
+	return sb.chars_needed;
+
+}
+
+char *myproto_msg_to_str(const struct myproto_msg *m)
+{
+	OSMO_NAME_C_IMPL(ctx, 256, "ERROR", myproto_msg_to_str_buf, m)
+}
+
+void test_enc_dec(const char *label, const struct osmo_gtlv_cfg *cfg, bool ordered)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(tests); i++) {
+		int rc;
+		const struct myproto_msg *orig = &tests[i];
+		struct myproto_msg parsed = {};
+		struct msgb *msg;
+
+		printf("\n=== start %s %s[%d]\n", label, __func__, i);
+		printf("encoded: %s\n", myproto_msg_to_str(orig));
+
+		msg = msgb_alloc(1024, __func__);
+		rc = myproto_msg_enc(msg, orig, cfg);
+		printf("myproto_msg_enc() rc = %d\n", rc);
+		printf("%s.\n", osmo_hexdump(msg->data, msg->len));
+
+		rc = myproto_msg_dec(&parsed, msg->data, msg->len, cfg, ordered);
+		printf("myproto_msg_dec() rc = %d\n", rc);
+		printf("decoded: %s\n", myproto_msg_to_str(&parsed));
+		if (strcmp(myproto_msg_to_str(orig), myproto_msg_to_str(&parsed))) {
+			printf(" ERROR: parsed != orig\n");
+			exit(1);
+		}
+
+		msgb_free(msg);
+		printf("=== end %s %s[%d]\n", label, __func__, i);
+	}
+}
+
+/* Example of defining a TLI, with an instance indicator */
+static int tliv_load_tl(struct osmo_gtlv_load *gtlv, const uint8_t *src_data, size_t src_data_len)
+{
+	/* already validated in next_tl_valid(): src_data_len >= cfg->tl_min_size == 2. */
+	gtlv->ti.tag = src_data[0];
+	gtlv->len = src_data[1];
+
+	switch (gtlv->ti.tag) {
+	/* All tags that are TLIV go here */
+	case MYPROTO_IEI_BAR:
+		if (src_data_len < 3)
+			return -ENOSPC;
+		gtlv->ti.instance_present = true;
+		gtlv->ti.instance = src_data[2];
+		gtlv->val = src_data + 3;
+		/* In this example, the I is part of the len */
+		gtlv->len--;
+		return 0;
+	default:
+		gtlv->val = src_data + 2;
+		return 0;
+	}
+}
+
+static int tliv_store_tl(uint8_t *dst_data, size_t dst_data_avail, const struct osmo_gtlv_tag_inst *ti, size_t len,
+			 struct osmo_gtlv_put *gtlv)
+{
+	if (ti->tag > UINT8_MAX)
+		return -EINVAL;
+	if (len > UINT8_MAX)
+		return -EMSGSIZE;
+	if (dst_data_avail < 2)
+		return -ENOSPC;
+
+	dst_data[0] = ti->tag;
+
+	switch (ti->tag) {
+	/* All tags that are TLIV go here */
+	case MYPROTO_IEI_BAR:
+		if (dst_data_avail < 3)
+			return -ENOSPC;
+		if (!ti->instance_present)
+			return -EINVAL;
+		if (ti->instance > UINT8_MAX)
+			return -EINVAL;
+		/* here, I is part of the len in L; the passed len reflects only the value, so add 1 for I */
+		dst_data[1] = len + 1;
+		dst_data[2] = ti->instance;
+		return 3;
+	default:
+		dst_data[1] = len;
+		return 2;
+	}
+}
+
+const struct osmo_gtlv_cfg osmo_tliv_cfg = {
+	.tl_min_size = 2,
+	.load_tl = tliv_load_tl,
+	.store_tl = tliv_store_tl,
+};
+
+int main()
+{
+	ctx = talloc_named_const(NULL, 0, "test_gen_tlv");
+	msgb_talloc_ctx_init(ctx, 0);
+
+	test_enc_dec("tliv ordered", &osmo_tliv_cfg, true);
+	test_enc_dec("tliv unordered", &osmo_tliv_cfg, false);
+
+	talloc_free(ctx);
+	return 0;
+}