initial drop of phosphor-ipmi-blobs
This implements a majority of the OEM IPMI BLOBS protocol. The only
piece missing from this is the timed expiration of sessions.
Change-Id: I82c9d17b625c94fc3340edcfabbbf1ffeb5ad7ac
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/crc.cpp b/crc.cpp
new file mode 100644
index 0000000..5fc4558
--- /dev/null
+++ b/crc.cpp
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * 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 "crc.hpp"
+
+namespace blobs
+{
+
+void Crc16::clear()
+{
+ value = crc16Initial;
+}
+
+// Origin: security/crypta/ipmi/portable/ipmi_utils.c
+void Crc16::compute(const uint8_t* bytes, uint32_t length)
+{
+ if (!bytes)
+ {
+ return;
+ }
+
+ const int kExtraRounds = 2;
+ const uint16_t kLeftBit = 0x8000;
+ uint16_t crc = value;
+ size_t i, j;
+
+ for (i = 0; i < length + kExtraRounds; ++i)
+ {
+ for (j = 0; j < 8; ++j)
+ {
+ bool xor_flag = crc & kLeftBit;
+ crc <<= 1;
+ // If this isn't an extra round and the current byte's j'th bit
+ // from the left is set, increment the CRC.
+ if (i < length && bytes[i] & (1 << (7 - j)))
+ {
+ crc++;
+ }
+ if (xor_flag)
+ {
+ crc ^= crc16Ccitt;
+ }
+ }
+ }
+
+ value = crc;
+}
+
+uint16_t Crc16::get() const
+{
+ return value;
+}
+} // namespace blobs