att: Add prepare write support

Add functions for encoding/decoding Prepare Write Request and
Response PDUs.

1 files changed, 54 insertions, 0 deletions

diff --git a/attrib/att.c b/attrib/att.c
index 0550ac13a..790ec3a9e 100644
--- a/attrib/att.c
+++ b/attrib/att.c
@@ -974,3 +974,57 @@ uint16_t dec_mtu_resp(const uint8_t *pdu, int len, uint16_t *mtu)
 
 	return min_len;
 }
+
+uint16_t enc_prep_write_req(uint16_t handle, uint16_t offset,
+			const uint8_t *value, int vlen, uint8_t *pdu, int len)
+{
+	const uint16_t min_len = sizeof(pdu[0]) + sizeof(handle) +
+								sizeof(offset);
+
+	if (pdu == NULL)
+		return 0;
+
+	if (len < min_len)
+		return 0;
+
+	if (vlen > len - min_len)
+		vlen = len - min_len;
+
+	pdu[0] = ATT_OP_PREP_WRITE_REQ;
+	att_put_u16(handle, &pdu[1]);
+	att_put_u16(offset, &pdu[3]);
+
+	if (vlen > 0) {
+		memcpy(&pdu[5], value, vlen);
+		return min_len + vlen;
+	}
+
+	return min_len;
+}
+
+uint16_t dec_prep_write_resp(const uint8_t *pdu, int len, uint16_t *handle,
+				uint16_t *offset, uint8_t *value, int *vlen)
+{
+	const uint16_t min_len = sizeof(pdu[0]) + sizeof(*handle) +
+								sizeof(*offset);
+
+	if (pdu == NULL)
+		return 0;
+
+	if (handle == NULL || offset == NULL || value == NULL || vlen == NULL)
+		return 0;
+
+	if (len < min_len)
+		return 0;
+
+	if (pdu[0] != ATT_OP_PREP_WRITE_REQ)
+		return 0;
+
+	*handle = att_get_u16(&pdu[1]);
+	*offset = att_get_u16(&pdu[3]);
+	*vlen = len - min_len;
+	if (*vlen > 0)
+		memcpy(value, pdu + min_len, *vlen);
+
+	return len;
+}