feat: Due to the deep modifications related to names and packet format,

this task cover a large part of the codebase and involves several changes:

- the library provides a name data structure (hicn_name_t ), which is composed
  of a name prefix (hicn_name_prefix_t) and a name suffix (hicn_name_suffix_t),
  and it has been extended to provide all support functions required for name
  manipulation, including common prefix computation, as required for the Longest
  Prefix Match (LPM)in the forwarder, in addition to Exact Prefix Match (EPM).
- all code has been rewritten to use this data structure instead of having for
  instance the forwarder define its own name class (used to be Name and NameBitVector)
  the code has been refactored to minimize name allocations and copies, one remaining
  aspect is the difference of name storage between PIT and CS entries (respectively
  in the PIT entry, and in the message buffer), which causes the packet cache
  index to be updated when a PIT entry is converted into a CS entry. By storing
  the name in the PIT/CS entry everytime, we might save on this operation).
- hicn-light FIB has been rewritten : code has been refactored and should now be
  shorter and documented; unit tests have been drafted but more would be required
  to cover all cases and match the algorithms to add/remove nodes, as specified in the doc.
  all protocol details and hICN header formats are now abstracted by the library
  for the forwarder (and thus header.h and  protocols/*.h have been removed from
  public includes, and replaced by packet.h providing protocol agnostic packet
  level functions, completely replacing the compat.h header that used to provide
  similar functions.
- this works by exposing a opaque buffer to the application (a kind of socket buffer)
  which is used by the lib to cache the packet format and offsets of the different
  layers in the buffer and provider efficient operations (the packet format is
  either defined for packet construction, or guessed at ingress, and this structure
  is updated accordingly only once).

Co-authored-by: Jordan Augé <jordan.auge+fdio@cisco.com>
Signed-off-by: Luca Muscariello <muscariello@ieee.org>
Change-Id: I31e321897f85f0267fe8ba4720363c180564492f

1 files changed, 112 insertions, 0 deletions

diff --git a/lib/src/protocol/ipv4.h b/lib/src/protocol/ipv4.h
new file mode 100644
index 000000000..5d729b955
--- /dev/null
+++ b/lib/src/protocol/ipv4.h
@@ -0,0 +1,112 @@
+/*
+ * 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.
+ */
+
+#ifndef HICN_PROTOCOL_IPV4
+#define HICN_PROTOCOL_IPV4
+
+#include <hicn/util/ip_address.h>
+
+#include <hicn/base.h>
+#include <hicn/common.h>
+
+/* Headers were adapted from linux' definitions in netinet/ip.h */
+
+/*
+ * The length of the IPV4 header struct must be 20 bytes.
+ */
+#define EXPECTED_IPV4_HDRLEN 20
+
+typedef struct
+{
+  union
+  {
+    struct
+    {
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+      u8 ihl : 4;
+      u8 version : 4;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+      u8 version : 4;
+      u8 ihl : 4;
+#else
+#error "Unsupported endianness"
+#endif
+    };
+
+    u8 version_ihl;
+  };
+  u8 tos;
+
+  /*
+   * This is the total length of the IP packet, including the IP header.
+   * NOTE: vriable len header size is currently not supported by the lib.
+   */
+  u16 len;
+
+  u16 id;
+  u16 frag_off;
+  u8 ttl;
+  u8 protocol;
+  u16 csum;
+  ipv4_address_t saddr;
+  ipv4_address_t daddr;
+} _ipv4_header_t;
+
+#define ipv4_header_bytes(ipv4_header)                                        \
+  (sizeof (u32) * (ipv4_header->version_ihl & 0xf))
+
+#define IPV4_HDRLEN sizeof (_ipv4_header_t)
+static_assert (EXPECTED_IPV4_HDRLEN == IPV4_HDRLEN,
+	       "Size of IPV4 struct does not match its expected size.");
+
+/*
+ * The length of the IPV4 pseudo header struct must be 12 bytes.
+ */
+#define EXPECTED_IPV4_PSHDRLEN 12
+
+typedef struct
+{
+  ipv4_address_t ip_src;
+  ipv4_address_t ip_dst;
+  u8 zero;
+  u8 protocol;
+  u16 size;
+} ipv4_pseudo_header_t;
+
+#define IPV4_PSHDRLEN sizeof (ipv4_pseudo_header_t)
+static_assert (EXPECTED_IPV4_PSHDRLEN == IPV4_PSHDRLEN,
+	       "Size of IPV4_PSHDR struct does not match its expected size.");
+
+/* Default field values */
+#define IPV4_DEFAULT_VERSION	    4
+#define IPV4_DEFAULT_IHL	    5
+#define IPV4_DEFAULT_TOS	    0
+#define IPV4_DEFAULT_PAYLOAD_LENGTH 0
+#define IPV4_DEFAULT_ID		    300
+#define IPV4_DEFAULT_FRAG_OFF	    0x000
+#define IPV4_DEFAULT_TTL	    64
+#define IPV4_DEFAULT_PROTOCOL	    IPPROTO_TCP
+#define IPV4_DEFAULT_SRC_IP	    0, 0, 0, 0
+#define IPV4_DEFAULT_DST_IP	    0, 0, 0, 0
+
+#endif /* HICN_PROTOCOL_IPV4 */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */