TLV: Add one-shot TLV encoder
So far, the TLV code contained two types of functions
* tlp_parse() to parse all TLVs according to definition into tlvp_parsed
* various helper functions to encode individual TLVs during message
generation
This patch implements the inverse of tlv_parse(): tlv_encode(), which
takes a full 'struct tlv_pared' and encodes all IEs found in it. The
order of IEs is in numerically ascending order of the tag.
As many protocols have different IE/TLV ordering requirements, let's add
a tlv_encode_ordered() function where the caller can specify the TLV
ordering during the one-shot encode.
Change-Id: I761a30bf20355a9f80a4a8e0c60b0b0f78515efe
diff --git a/src/gsm/tlv_parser.c b/src/gsm/tlv_parser.c
index 6e089f7..159b42b 100644
--- a/src/gsm/tlv_parser.c
+++ b/src/gsm/tlv_parser.c
@@ -120,6 +120,103 @@
return 0;
}
+
+/*! Encode a single TLV into given message buffer
+ * \param[inout] msg Caller-allocated message buffer with sufficient tailroom
+ * \param[in] type TLV type/format to use during encode
+ * \param[in] tag Tag of TLV to be encoded
+ * \parma[in] len Length of TLV to be encoded
+ * \param[in] val Value part of TLV to be encoded
+ * \returns 0 on success; negative in case of error */
+int tlv_encode_one(struct msgb *msg, enum tlv_type type, uint8_t tag,
+ unsigned int len, const uint8_t *val)
+{
+ switch (type) {
+ case TLV_TYPE_NONE:
+ break;
+ case TLV_TYPE_FIXED:
+ msgb_tv_fixed_put(msg, tag, len, val);
+ break;
+ case TLV_TYPE_T:
+ msgb_v_put(msg, tag);
+ break;
+ case TLV_TYPE_TV:
+ msgb_tv_put(msg, tag, val[0]);
+ break;
+ case TLV_TYPE_TLV:
+ msgb_tlv_put(msg, tag, len, val);
+ break;
+ case TLV_TYPE_TL16V:
+ msgb_tl16v_put(msg, tag, len, val);
+ break;
+ case TLV_TYPE_TvLV:
+ msgb_tvlv_put(msg, tag, len, val);
+ break;
+ case TLV_TYPE_SINGLE_TV:
+ msgb_v_put(msg, (tag << 4) | (val[0] & 0xf));
+ break;
+ case TLV_TYPE_vTvLV_GAN:
+ msgb_vtvlv_gan_put(msg, tag, len, val);
+ break;
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/*! Encode a set of decoded TLVs according to a given definition into a message buffer
+ * \param[inout] msg Caller-allocated message buffer with sufficient tailroom
+ * \param[in] def structure defining the valid TLV tags / configurations
+ * \param[in] tp decoded values to be encoded
+ * \returns number of bytes consumed in msg; negative in case of error */
+int tlv_encode(struct msgb *msg, const struct tlv_definition *def, const struct tlv_parsed *tp)
+{
+ unsigned int tailroom_before = msgb_tailroom(msg);
+ unsigned int i;
+ int rc;
+
+ for (i = 0; i < ARRAY_SIZE(tp->lv); i++) {
+ /* skip entries in the array that aren't used/filled */
+ if (!TLVP_PRESENT(tp, i))
+ continue;
+
+ rc = tlv_encode_one(msg, def->def[i].type, i, TLVP_LEN(tp, i), TLVP_VAL(tp, i));
+ if (rc < 0)
+ return rc;
+ }
+
+ return tailroom_before - msgb_tailroom(msg);
+}
+
+/*! Encode a set of decoded TLVs according to a given definition and IE order into a message buffer
+ * \param[inout] msg Caller-allocated message buffer with sufficient tailroom
+ * \param[in] def structure defining the valid TLV tags / configurations
+ * \param[in] tp decoded values to be encoded
+ * \param[in] tag_order array of tags determining the IE encoding order
+ * \param[in] tag_order_len length of tag_order
+ * \returns number of bytes consumed in msg; negative in case of error */
+int tlv_encode_ordered(struct msgb *msg, const struct tlv_definition *def, const struct tlv_parsed *tp,
+ const uint8_t *tag_order, unsigned int tag_order_len)
+{
+
+ unsigned int tailroom_before = msgb_tailroom(msg);
+ unsigned int i;
+ int rc;
+
+ for (i = 0; i < tag_order_len; i++) {
+ uint8_t tag = tag_order[i];
+
+ /* skip entries in the array that aren't used/filled */
+ if (!TLVP_PRESENT(tp, tag))
+ continue;
+
+ rc = tlv_encode_one(msg, def->def[tag].type, tag, TLVP_LEN(tp, tag), TLVP_VAL(tp, tag));
+ if (rc < 0)
+ return rc;
+ }
+ return tailroom_before - msgb_tailroom(msg);
+}
+
/*! Parse a single TLV encoded IE
* \param[out] o_tag the tag of the IE that was found
* \param[out] o_len length of the IE that was found