dsp: base: Added decode_pldm_base_negotiate_transfer_params_req()

This command is based on DSP0240 v1.2.0 section 9.6.2
NegotiateTransferParameters (0x07).

gitlint-ignore: T1
Change-Id: I4fa193444df9ba5b109ca063163d7f7d109fcbda
Signed-off-by: Kasun Athukorala <kasunath@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6f5ae18..eb7e9a8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@
 - platform: Added file descriptor PDR encoding support
   - Added `encode_pldm_platform_file_descriptor_pdr()`
 - utils: Added `pldm_edac_crc32_extend()`
+- base: Added `decode_pldm_base_negotiate_transfer_params_req()`
 
 ### Changed
 
diff --git a/include/libpldm/base.h b/include/libpldm/base.h
index 65a826e..b76b9f3 100644
--- a/include/libpldm/base.h
+++ b/include/libpldm/base.h
@@ -815,6 +815,24 @@
 	const struct pldm_base_negotiate_transfer_params_req *req,
 	struct pldm_msg *msg, size_t *payload_length);
 
+/** @brief Decode a PLDM Negotiate Transfer Parameters request message
+ *
+ *  @param[in] msg - Request message
+ *  @param[in] payload_length - length of request message payload
+ *  @param[out] req - pointer to the decoded request message
+ *  @return 0 on success
+ *          -EINVAL if the input parameters' memory are not allocated
+ *          -EOVERFLOW if the input message buffer is too short for the output
+ *          request struct
+ *          -EBADMSG if the input message buffer is too large for the output
+ *          request struct
+ *  @note  Caller is responsible for memory alloc and dealloc of param
+ *         'msg.payload'
+ */
+int decode_pldm_base_negotiate_transfer_params_req(
+	const struct pldm_msg *msg, size_t payload_length,
+	struct pldm_base_negotiate_transfer_params_req *req);
+
 /** @brief Decode a PLDM Negotiate Transfer Parameters response message
  *
  *  @param[in] msg - Response message
diff --git a/src/dsp/base.c b/src/dsp/base.c
index 816a871..88dc883 100644
--- a/src/dsp/base.c
+++ b/src/dsp/base.c
@@ -832,7 +832,39 @@
 	return pldm_msgbuf_complete_used(buf, *payload_length, payload_length);
 }
 
-LIBPLDM_ABI_STABLE
+LIBPLDM_ABI_TESTING
+int decode_pldm_base_negotiate_transfer_params_req(
+	const struct pldm_msg *msg, size_t payload_length,
+	struct pldm_base_negotiate_transfer_params_req *req)
+{
+	PLDM_MSGBUF_RO_DEFINE_P(buf);
+	int rc;
+
+	if (msg == NULL || req == NULL) {
+		return -EINVAL;
+	}
+
+	rc = pldm_msgbuf_init_errno(
+		buf, PLDM_BASE_NEGOTIATE_TRANSFER_PARAMETERS_REQ_BYTES,
+		msg->payload, payload_length);
+	if (rc) {
+		return rc;
+	}
+
+	pldm_msgbuf_extract(buf, req->requester_part_size);
+
+	rc = pldm_msgbuf_extract_array(
+		buf, sizeof(req->requester_protocol_support),
+		(uint8_t *)req->requester_protocol_support,
+		sizeof(req->requester_protocol_support));
+	if (rc) {
+		return pldm_msgbuf_discard(buf, rc);
+	}
+
+	return pldm_msgbuf_complete_consumed(buf);
+}
+
+LIBPLDM_ABI_TESTING
 int decode_pldm_base_negotiate_transfer_params_resp(
 	const struct pldm_msg *msg, size_t payload_length,
 	struct pldm_base_negotiate_transfer_params_resp *resp)
diff --git a/tests/dsp/base.cpp b/tests/dsp/base.cpp
index 0e274a8..80edb62 100644
--- a/tests/dsp/base.cpp
+++ b/tests/dsp/base.cpp
@@ -1741,3 +1741,95 @@
     EXPECT_EQ(rc, -EOVERFLOW);
 }
 #endif
+
+#ifdef LIBPLDM_API_TESTING
+TEST(NegotiateTransferParams, TestDecodeNegotiateTransferParamsReqPass)
+{
+    // Prepare a sample request message
+    uint8_t instance_id = 0x0A;
+    uint16_t requester_part_size = 1024; // 0x0400
+    bitfield8_t requester_protocol_support[8];
+    for (int i = 0; i < 8; ++i)
+    {
+        requester_protocol_support[i].byte = static_cast<uint8_t>(i + 1);
+    }
+
+    PLDM_MSG_DEFINE_P(request,
+                      PLDM_BASE_NEGOTIATE_TRANSFER_PARAMETERS_REQ_BYTES);
+
+    // Build the request using the an appropriate API
+    struct pldm_base_negotiate_transfer_params_req req;
+    req.requester_part_size = requester_part_size;
+    memcpy(req.requester_protocol_support, requester_protocol_support,
+           sizeof(requester_protocol_support));
+
+    size_t req_payload_len = PLDM_BASE_NEGOTIATE_TRANSFER_PARAMETERS_REQ_BYTES;
+    ASSERT_EQ(encode_pldm_base_negotiate_transfer_params_req(
+                  instance_id, &req, request, &req_payload_len),
+              0);
+
+    struct pldm_base_negotiate_transfer_params_req decoded_req;
+    size_t payload_len = PLDM_BASE_NEGOTIATE_TRANSFER_PARAMETERS_REQ_BYTES;
+
+    // Successful decode
+    int rc = decode_pldm_base_negotiate_transfer_params_req(
+        request, payload_len, &decoded_req);
+    ASSERT_EQ(rc, 0);
+    EXPECT_EQ(decoded_req.requester_part_size, requester_part_size);
+    for (int i = 0; i < 8; ++i)
+    {
+        EXPECT_EQ(decoded_req.requester_protocol_support[i].byte,
+                  requester_protocol_support[i].byte);
+    }
+}
+#endif
+
+#ifdef LIBPLDM_API_TESTING
+TEST(NegotiateTransferParams, TestDecodeNegotiateTransferParamsReqFail)
+{
+    // Prepare a sample request message
+    uint8_t instance_id = 0x0A;
+    uint16_t requester_part_size = 1024; // 0x0400
+    bitfield8_t requester_protocol_support[8];
+    for (int i = 0; i < 8; ++i)
+    {
+        requester_protocol_support[i].byte = static_cast<uint8_t>(i + 1);
+    }
+
+    PLDM_MSG_DEFINE_P(request,
+                      PLDM_BASE_NEGOTIATE_TRANSFER_PARAMETERS_REQ_BYTES);
+
+    // Build the request using the an appropriate API
+    struct pldm_base_negotiate_transfer_params_req req;
+    req.requester_part_size = requester_part_size;
+    memcpy(req.requester_protocol_support, requester_protocol_support,
+           sizeof(requester_protocol_support));
+
+    size_t req_payload_len = PLDM_BASE_NEGOTIATE_TRANSFER_PARAMETERS_REQ_BYTES;
+    ASSERT_EQ(encode_pldm_base_negotiate_transfer_params_req(
+                  instance_id, &req, request, &req_payload_len),
+              0);
+
+    struct pldm_base_negotiate_transfer_params_req decoded_req;
+    size_t payload_len = PLDM_BASE_NEGOTIATE_TRANSFER_PARAMETERS_REQ_BYTES;
+    int rc = 0;
+
+    // Null arguments
+    rc = decode_pldm_base_negotiate_transfer_params_req(nullptr, payload_len,
+                                                        &decoded_req);
+    EXPECT_EQ(rc, -EINVAL);
+    rc = decode_pldm_base_negotiate_transfer_params_req(request, payload_len,
+                                                        nullptr);
+    EXPECT_EQ(rc, -EINVAL);
+
+    // Incorrect payload length - too short
+    rc = decode_pldm_base_negotiate_transfer_params_req(
+        request, payload_len - 1, &decoded_req);
+    EXPECT_EQ(rc, -EOVERFLOW);
+
+    // Incorrect payload length - too long
+    rc = decode_pldm_base_negotiate_transfer_params_req(
+        request, payload_len + 1, &decoded_req);
+    EXPECT_EQ(rc, -EBADMSG);
+}
+#endif