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, 24 insertions, 4 deletions

diff --git a/include/osmocom/gtlv/gtlv.h b/include/osmocom/gtlv/gtlv.h
index 7acf558..d800f71 100644
--- a/include/osmocom/gtlv/gtlv.h
+++ b/include/osmocom/gtlv/gtlv.h
@@ -25,10 +25,25 @@
 
 #include <stdint.h>
 #include <stdio.h>
+#include <stdbool.h>
 
 struct msgb;
 struct osmo_gtlv_load;
 struct osmo_gtlv_put;
+struct value_string;
+
+struct osmo_gtlv_tag_inst {
+	unsigned int tag;
+	bool instance_present;
+	unsigned int instance;
+};
+
+int osmo_gtlv_tag_inst_cmp(const struct osmo_gtlv_tag_inst *a, const struct osmo_gtlv_tag_inst *b);
+
+int osmo_gtlv_tag_inst_to_str_buf(char *buf, size_t buflen, const struct osmo_gtlv_tag_inst *ti,
+				 const struct value_string *tag_names);
+char *osmo_gtlv_tag_inst_to_str_c(void *ctx, const struct osmo_gtlv_tag_inst *ti,
+				 const struct value_string *tag_names);
 
 /*! TL configuration for osmo_gtlv_load*() and osmo_gtlv_put*(). Depending on these implementations provided by the caller,
  * osmo_gtlv can load any sizes of tag and length fields (that don't surpass the value range of unsigned int and size_t,
@@ -49,6 +64,7 @@ struct osmo_gtlv_cfg {
 	/*! Read one TL from the start of src_data.
 	 * \param gtlv  Return the T (tag) value read from src_data in gtlv->tag.
 	 *             Return the L (length) value read from src_data in gtlv->len.
+	 *             Return the I (instance) value read from src_data in gtlv->len; ignore if there is no I.
 	 *             Return the position just after the TL in gtlv->*val. If there is V data, point at the start of the
 	 *             V data in src_data. If there is no V data, point at the byte just after the TL part in src_data.
 	 * \param src_data  Part of raw message being decoded.
@@ -68,12 +84,14 @@ struct osmo_gtlv_cfg {
 	 * \param dst_data  Write TL data to the start of this buffer.
 	 * \param dst_data_avail  Remaining available space in dst_data.
 	 * \param tag  The T value to store in dst_data.
+	 * \param instance  The I value to store in dst_data (if this tag is a TLIV); ignore when not a TLIV.
 	 * \param len  The L value to store in dst_data.
 	 * \param gtlv  Backpointer to the osmo_gtlv_put struct, including gtlv->dst, the underlying msgb.
 	 * \return the size of the TL part in bytes on success, -EINVAL if tag is invalid, -EMSGSIZE if len is too large
 	 * or dst_data_avail is too small for the TL.
 	 */
-	int (*store_tl)(uint8_t *dst_data, size_t dst_data_avail, unsigned int tag, size_t len, struct osmo_gtlv_put *gtlv);
+	int (*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);
 };
 
 /*! Configuration that allows parsing an 8bit tag and 8bit length TLV. */
@@ -97,7 +115,7 @@ struct osmo_gtlv_load {
 	} src;
 
 	/*! Return value from last invocation of osmo_gtlv_load_next*(): tag value of parsed IE. */
-	unsigned int tag;
+	struct osmo_gtlv_tag_inst ti;
 	/*! Return value from last invocation of osmo_gtlv_load_next*(): Start of the IE's payload data (after tag and
 	 * length). If the end of the src buffer is reached, val == NULL. If a TLV contained no value part, len == 0,
 	 * but this still points just after the TL. */
@@ -114,8 +132,9 @@ static inline void osmo_gtlv_load_start(struct osmo_gtlv_load *gtlv)
 }
 
 int osmo_gtlv_load_next(struct osmo_gtlv_load *gtlv);
-int osmo_gtlv_load_peek_tag(const struct osmo_gtlv_load *gtlv);
+int osmo_gtlv_load_peek_tag(const struct osmo_gtlv_load *gtlv, struct osmo_gtlv_tag_inst *ti);
 int osmo_gtlv_load_next_by_tag(struct osmo_gtlv_load *gtlv, unsigned int tag);
+int osmo_gtlv_load_next_by_tag_inst(struct osmo_gtlv_load *gtlv, const struct osmo_gtlv_tag_inst *ti);
 
 /* State for storing a TLV structure into a msgb. */
 struct osmo_gtlv_put {
@@ -128,10 +147,11 @@ struct osmo_gtlv_put {
 	/* msgb to append new TL to */
 	struct msgb *dst;
 	/* What was the last TL written and where are its TL and V */
-	unsigned int last_tag;
+	struct osmo_gtlv_tag_inst last_ti;
 	uint8_t *last_tl;
 	uint8_t *last_val;
 };
 
 int osmo_gtlv_put_tl(struct osmo_gtlv_put *gtlv, unsigned int tag, size_t len);
+int osmo_gtlv_put_tli(struct osmo_gtlv_put *gtlv, const struct osmo_gtlv_tag_inst *ti, size_t len);
 int osmo_gtlv_put_update_tl(struct osmo_gtlv_put *gtlv);