Add SW Description (de)marshalling

* data structure representing 3GPP TS 52.021 §9.4.62 SW Description
* function to serialize it into msgb
* function to deserialize it from buffer
* functions to extract/estimate buffer size for SW Description
* test harness (partially taken from OpenBSC)

There are several similar functions to deal with SW Description in
OpenBSC, there's also need to use similar functionality in
OsmoBTS. Hence it's better to put the code into common library with
proper tests and documentation.

Change-Id: Ib63b6b5e83b8914864fc7edd789f8958cdc993cd
Related: OS#1614

1 files changed, 155 insertions, 0 deletions

diff --git a/src/gsm/abis_nm.c b/src/gsm/abis_nm.c
index 934d7ceb..7553f84d 100644
--- a/src/gsm/abis_nm.c
+++ b/src/gsm/abis_nm.c
@@ -751,6 +751,161 @@ struct msgb *abis_nm_fail_evt_vrep(enum abis_nm_event_type t,
 	return nmsg;
 }
 
+/*! \brief Compute length of given 3GPP TS 52.021 §9.4.62 SW Description.
+ *  \param[in] sw SW Description struct
+ *  \param[in] put_sw_descr boolean, whether to put NM_ATT_SW_DESCR IE or not
+ *  \returns length of buffer space necessary to store sw
+ */
+uint16_t abis_nm_sw_desc_len(const struct abis_nm_sw_desc *sw, bool put_sw_desc)
+{
+	/* +3: type is 1-byte, length is 2-byte */
+	return (put_sw_desc ? 1 : 0) + (sw->file_id_len + 3) + (sw->file_version_len + 3);
+}
+
+/*! \brief Put given 3GPP TS 52.021 §9.4.62 SW Description into msgb.
+ *  \param[out] msg message buffer
+ *  \param[in] sw SW Description struct
+ *  \param[in] put_sw_descr boolean, whether to put NM_ATT_SW_DESCR IE or not
+ *  \returns length of buffer space necessary to store sw
+ */
+uint16_t abis_nm_put_sw_desc(struct msgb *msg, const struct abis_nm_sw_desc *sw, bool put_sw_desc)
+{
+	if (put_sw_desc)
+		msgb_v_put(msg, NM_ATT_SW_DESCR);
+
+	msgb_tl16v_put(msg, NM_ATT_FILE_ID, sw->file_id_len, sw->file_id);
+	msgb_tl16v_put(msg, NM_ATT_FILE_VERSION, sw->file_version_len, sw->file_version);
+
+	return abis_nm_sw_desc_len(sw, put_sw_desc);
+}
+
+/*! \brief Put given file ID/Version pair as 3GPP TS 52.021 §9.4.62 SW Description into msgb.
+ *  \param[out] msg message buffer
+ *  \param[in] id File ID part of SW Description
+ *  \param[in] id File Version part of SW Description
+ *  \param[in] put_sw_descr boolean, whether to put NM_ATT_SW_DESCR IE or not
+ *  \returns length of buffer space necessary to store sw
+ */
+uint16_t abis_nm_put_sw_file(struct msgb *msg, const char *id, const char *ver, bool put_sw_desc)
+{
+	struct abis_nm_sw_desc sw = {
+		.file_id_len = strlen(id),
+		.file_version_len = strlen(ver),
+	};
+
+	memcpy(sw.file_id, id, sw.file_id_len);
+	memcpy(sw.file_version, ver, sw.file_version_len);
+
+	return abis_nm_put_sw_desc(msg, &sw, put_sw_desc);
+}
+
+/*! \brief Get length of first 3GPP TS 52.021 §9.4.62 SW Description from buffer.
+ *  \param[in] buf buffer, may contain several SW Descriptions
+ *  \param[in] len buffer length
+ *  \returns length if parsing succeeded, 0 otherwise
+ */
+uint32_t abis_nm_get_sw_desc_len(const uint8_t *buf, size_t len)
+{
+	uint16_t sw = 2; /* 1-byte SW tag + 1-byte FILE_* tag */
+
+	if (buf[0] != NM_ATT_SW_DESCR)
+		sw = 1; /* 1-byte FILE_* tag */
+
+	if (buf[sw - 1] != NM_ATT_FILE_ID && buf[sw - 1] != NM_ATT_FILE_VERSION)
+		return 0;
+
+	/* + length of 1st FILE_* element + 1-byte tag + 2-byte length field of
+	   1st FILE_* element */
+	sw += (osmo_load16be(buf + sw) + 3);
+
+	/* + length of 2nd FILE_* element */
+	sw += osmo_load16be(buf + sw);
+
+	return sw + 2; /* +  2-byte length field of 2nd FILE_* element */
+}
+
+/*! \brief Parse single 3GPP TS 52.021 §9.4.62 SW Description from buffer.
+ *  \param[out] sw SW Description struct
+ *  \param[in] buf buffer
+ *  \param[in] len buffer length
+ *  \returns 0 if parsing succeeded, negative error code otherwise
+ */
+static inline int abis_nm_get_sw_desc(struct abis_nm_sw_desc *sw, const uint8_t *buf, size_t length)
+{
+	int rc;
+	uint32_t len = abis_nm_get_sw_desc_len(buf, length);
+	static struct tlv_parsed tp;
+	const struct tlv_definition sw_tlvdef = {
+		.def = {
+			[NM_ATT_SW_DESCR] =		{ TLV_TYPE_TV },
+			[NM_ATT_FILE_ID] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_FILE_VERSION] =		{ TLV_TYPE_TL16V },
+		},
+	};
+
+	/* Basic sanity check */
+	if (len > length)
+		return -EFBIG;
+
+	/* Note: current implementation of TLV parser fails on multilpe SW Descr:
+	   we will only parse the first one */
+	if (!len)
+		return -EINVAL;
+
+	/* Note: the return value is ignored here because SW Description tag
+	   itself is considered optional. */
+	tlv_parse(&tp, &sw_tlvdef, buf, len, 0, 0);
+
+	/* Parsing SW Description is tricky for current implementation of TLV
+	   parser which fails to properly handle TV when V has following
+	   structure: | TL16V | TL16V |. Hence, the need for 2nd call: */
+	rc = tlv_parse(&tp, &sw_tlvdef, buf + TLVP_LEN(&tp, NM_ATT_SW_DESCR), len - TLVP_LEN(&tp, NM_ATT_SW_DESCR),
+		       0, 0);
+
+	if (rc < 0)
+		return rc;
+
+	if (!TLVP_PRESENT(&tp, NM_ATT_FILE_ID))
+		return -EBADF;
+
+	if (!TLVP_PRESENT(&tp, NM_ATT_FILE_VERSION))
+		return -EBADMSG;
+
+	sw->file_id_len = TLVP_LEN(&tp, NM_ATT_FILE_ID);
+	sw->file_version_len = TLVP_LEN(&tp, NM_ATT_FILE_VERSION);
+
+	memcpy(sw->file_id, TLVP_VAL(&tp, NM_ATT_FILE_ID), sw->file_id_len);
+	memcpy(sw->file_version, TLVP_VAL(&tp, NM_ATT_FILE_VERSION), sw->file_version_len);
+
+	return 0;
+}
+
+/*! \brief Parse 3GPP TS 52.021 §9.4.61 SW Configuration from buffer.
+ *  \param[in] buf buffer
+ *  \param[in] buf_len buffer length
+ *  \param[out] sw SW Description struct array
+ *  \param[in] sw_len Expected number of SW Description entries
+ *  \returns 0 if parsing succeeded, negative error code otherwise
+ */
+int abis_nm_get_sw_conf(const uint8_t * buf, size_t buf_len, struct abis_nm_sw_desc *sw, uint16_t sw_len)
+{
+	int rc;
+	uint16_t len = 0, i;
+	for (i = 0; i < sw_len; i++) {
+		memset(&sw[i], 0, sizeof(sw[i]));
+		rc = abis_nm_get_sw_desc(&sw[i], buf + len, buf_len - len);
+		if (rc < 0)
+			return rc;
+
+		len += abis_nm_get_sw_desc_len(buf + len, buf_len - len);
+
+		if (len >= buf_len)
+			return i + 1;
+	}
+
+	return i;
+}
+
 /*! \brief Obtain OML Channel Combination for phnsical channel config */
 int abis_nm_chcomb4pchan(enum gsm_phys_chan_config pchan)
 {