1 files changed, 83 insertions, 0 deletions
diff --git a/lib/src/protocol/ah.h b/lib/src/protocol/ah.h
new file mode 100644
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+++ b/lib/src/protocol/ah.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2021-2022 Cisco and/or its affiliates.
+ * 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.
+ */
+
+/**
+ * @file protocol/ah.h
+ * @brief AH packet header
+ */
+#ifndef HICN_PROTOCOL_AH_H
+#define HICN_PROTOCOL_AH_H
+
+#include <hicn/common.h>
+
+/*
+ * The TCP PSH flag is set to indicate TCP payload in fact contains a AH header
+ * with signature information for the packet
+ */
+#define AH_FLAG 0x10
+
+/*
+ * The length of the AH struct must be 44 bytes.
+ */
+#define EXPECTED_AH_HDRLEN 44
+
+typedef struct
+{
+  u8 nh; // To match with reserved in IPSEC AH
+  // Length of the signature field. Note that the signature might be smaller
+  // than the field: the actual size is computed from the field size and
+  // signaturePadding.
+  u8 payloadlen;
+  union
+  {
+    u16 reserved;
+
+    struct
+    {
+      u8 validationAlgorithm;
+      u8 signaturePadding;
+    };
+  };
+  union
+  {
+    struct
+    {
+      u32 spi;
+      u32 seq;
+    };
+    // Unix timestamp indicating when the signature has been calculated
+    u8 timestamp_as_u8[8];
+    u16 timestamp_as_u16[4];
+    u32 timestamp_as_u32[2];
+  };
+  // ICV would follow
+  u8 keyId[32]; // Hash of pub key
+  /* 44 B + validationPayload */
+  u8 validationPayload[0]; // Holds the signature
+} _ah_header_t;
+
+#define AH_HDRLEN sizeof (_ah_header_t)
+static_assert (EXPECTED_AH_HDRLEN == AH_HDRLEN,
+	       "Size of AH Struct does not match its expected size.");
+
+#endif /* HICN_PROTOCOL_AH_H */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */