ipmbbridge initial implementation

ipmbbridge gives the ability for openbmc to host ipmb transactions over
smbus

Change-Id: I3744dbef5a6db0b2ff4f2b691e68ca8dc3b1d24b
Signed-off-by: Dawid Frycki <dawid.frycki@intel.com>
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/ipmbutils.cpp b/ipmbutils.cpp
new file mode 100644
index 0000000..d9a440e
--- /dev/null
+++ b/ipmbutils.cpp
@@ -0,0 +1,90 @@
+/* Copyright 2018 Intel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#include "ipmbbridged.hpp"
+#include "ipmbdefines.hpp"
+
+#include <inttypes.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/**
+ * @brief Ipmb utils for checksum
+ */
+bool ipmbChecksumValidate(uint8_t *data, uint8_t length)
+{
+    uint8_t checksum = 0;
+
+    // compute checksum.
+    for (uint8_t idx = 0; idx < length; idx++)
+    {
+        checksum += data[idx];
+    }
+
+    // check if checksum is valid.
+    if (0 == checksum)
+    {
+        // checksum valid.
+        return true;
+    }
+    else
+    {
+        // checksum invalid.
+        return false;
+    }
+}
+
+uint8_t ipmbChecksumCompute(uint8_t *data, uint8_t length)
+{
+    uint8_t checksum = 0;
+
+    // compute checksum.
+    for (uint8_t idx = 0; idx < length; idx++)
+    {
+        checksum += data[idx];
+    }
+
+    checksum = (~checksum) + 1;
+
+    // return computed checksum value.
+    return checksum;
+}
+
+inline bool ipmbConnectionHeaderChecksumValidate(IPMB_HEADER *ipmbHeader)
+{
+    return ipmbChecksumValidate(reinterpret_cast<uint8_t *>(ipmbHeader),
+                                ipmbConnectionHeaderLength);
+}
+
+inline bool ipmbDataChecksumValidate(IPMB_HEADER *ipmbHeader, uint8_t length)
+{
+    return ipmbChecksumValidate(
+        (reinterpret_cast<uint8_t *>(ipmbHeader) + ipmbConnectionHeaderLength),
+        (length - ipmbConnectionHeaderLength));
+}
+
+bool isFrameValid(IPMB_HEADER *frame, uint8_t length)
+{
+    bool frameValid = ipmbConnectionHeaderChecksumValidate(frame);
+    if (false == frameValid)
+    {
+        // invalid connection header checksum.
+        return false;
+    }
+
+    // data checksum validation.
+    return ipmbDataChecksumValidate(frame, length);
+}