[HICN-690] Transport Library Major Refactory

The current patch provides a major refactory of the transportlibrary.
A summary of the different components that underwent major modifications is
reported below.

- Transport protocol updates
The hierarchy of classes has been optimized to have common transport services
across different transport protocols. This can allow to customize a transport
protocol with new features.

- A new real-time communication protocol
The RTC protocol has been optimized in terms of algorithms to reduce
consumer-producer synchronization latency.

- A novel socket API
The API has been reworked to be easier to consumer but also to have a more
efficient integration in L4 proxies.

- Several performance improvements
A large number of performance improvements have been included in
particular to make the entire stack zero-copy and optimize cache miss.

- New memory buffer framework
Memory management has been reworked entirely to provide a more efficient infra
with a richer API. Buffers are now allocated in blocks and a single buffer
holds the memory for (1) the shared_ptr control block, (2) the metadata of the
packet (e.g. name, pointer to other buffers if buffer is chained and relevant
offsets), and (3) the packet itself, as it is sent/received over the network.

- A new slab allocator
Dynamic memory allocation is now managed by a novel slab allocator that is
optimised for packet processing and connection management. Memory is organized
in pools of blocks all of the same size which are used during the processing of
outgoing/incoming packets. When a memory block Is allocated is always taken
from a global pool and when it is deallocated is returned to the pool, thus
avoiding the cost of any heap allocation in the data path.

- New transport connectors
Consumer and producer end-points can communication either using an hicn packet
forwarder or with direct connector based on shared memories or sockets.
The usage of transport connectors typically for unit and funcitonal
testing but may have additional usage.

- Support for FEC/ECC for transport services
FEC/ECC via reed solomon is supported by default and made available to
transport services as a modular component. Reed solomon block codes is a
default FEC model that can be replaced in a modular way by many other
codes including RLNC not avaiable in this distribution.
The current FEC framework support variable size padding and efficiently
makes use of the infra memory buffers to avoid additiona copies.

- Secure transport framework for signature computation and verification
Crypto support is nativelty used in hICN for integrity and authenticity.
Novel support that includes RTC has been implemented and made modular
and reusable acrosso different transport protocols.

- TLS - Transport layer security over hicn
Point to point confidentiality is provided by integrating TLS on top of
hICN reliable and non-reliable transport. The integration is common and
makes a different use of the TLS record.

- MLS - Messaging layer security over hicn
MLS integration on top of hICN is made by using the MLSPP implemetation
open sourced by Cisco. We have included instrumentation tools to deploy
performance and functional tests of groups of end-points.

- Android support
The overall code has been heavily tested in Android environments and
has received heavy lifting to better run natively in recent Android OS.

Co-authored-by: Mauro Sardara <msardara@cisco.com>
Co-authored-by: Michele Papalini <micpapal@cisco.com>
Co-authored-by: Olivier Roques <oroques+fdio@cisco.com>
Co-authored-by: Giulio Grassi <gigrassi@cisco.com>
Change-Id: If477ba2fa686e6f47bdf96307ac60938766aef69
Signed-off-by: Luca Muscariello <muscariello@ieee.org>

1 files changed, 338 insertions, 0 deletions

diff --git a/libtransport/src/core/rs.h b/libtransport/src/core/rs.h
new file mode 100644
index 000000000..d630bd233
--- /dev/null
+++ b/libtransport/src/core/rs.h
@@ -0,0 +1,338 @@
+
+/*
+ * Copyright (c) 2021 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.
+ */
+
+#include <arpa/inet.h>
+#include <hicn/transport/utils/membuf.h>
+#include <protocols/fec_base.h>
+
+#include <array>
+#include <cstdint>
+#include <map>
+#include <unordered_set>
+#include <vector>
+
+namespace transport {
+namespace core {
+
+namespace fec {
+
+static const constexpr uint16_t MAX_SOURCE_BLOCK_SIZE = 128;
+
+using buffer = typename utils::MemBuf::Ptr;
+/**
+ * We use a std::array in place of std::vector to avoid to allocate a new vector
+ * in the heap every time we build a new source block, which would be bad if
+ * the decoder has to allocate several source blocks for many concurrent bases.
+ * std::array allows to be constructed in place, saving the allocation at the
+ * price os knowing in advance its size.
+ */
+using Packets = std::array<std::pair<uint32_t, buffer>, MAX_SOURCE_BLOCK_SIZE>;
+
+/**
+ * FEC Header, prepended to symbol packets.
+ */
+struct fec_header {
+  /**
+   * The base source packet seq_number this FES symbol refers to
+   */
+  uint32_t seq_number;
+
+  /**
+   * The index of the symbol inside the source block, between k and n - 1
+   */
+  uint8_t encoded_symbol_id;
+
+  /**
+   * Total length of source block (n)
+   */
+  uint8_t source_block_len;
+
+  /**
+   * Total number of symbols (n - k)
+   */
+  uint8_t n_fec_symbols;
+
+  /**
+   * Align header to 64 bits
+   */
+  uint8_t padding;
+
+  void setSeqNumberBase(uint32_t suffix) { seq_number = htonl(suffix); }
+  uint32_t getSeqNumberBase() { return ntohl(seq_number); }
+  void setEncodedSymbolId(uint8_t esi) { encoded_symbol_id = esi; }
+  uint8_t getEncodedSymbolId() { return encoded_symbol_id; }
+  void setSourceBlockLen(uint8_t k) { source_block_len = k; }
+  uint8_t getSourceBlockLen() { return source_block_len; }
+  void setNFecSymbols(uint8_t n_r) { n_fec_symbols = n_r; }
+  uint8_t getNFecSymbols() { return n_fec_symbols; }
+};
+
+/**
+ * This class models the source block itself.
+ */
+class BlockCode : public Packets {
+  /**
+   * For variable length packet we need to prepend to the padded payload the
+   * real length of the packet. This is *not* sent over the network.
+   */
+  static constexpr std::size_t LEN_SIZE_BYTES = 2;
+
+ public:
+  BlockCode(uint32_t k, uint32_t n, struct fec_parms *code);
+
+  /**
+   * Add a repair symbol to the dource block.
+   */
+  bool addRepairSymbol(const fec::buffer &packet, uint32_t i);
+
+  /**
+   * Add a source symbol to the source block.
+   */
+  bool addSourceSymbol(const fec::buffer &packet, uint32_t i);
+
+  /**
+   * Get current length of source block.
+   */
+  std::size_t length() { return current_block_size_; }
+
+  /**
+   * Get N
+   */
+  uint32_t getN() { return n_; }
+
+  /**
+   * Get K
+   */
+  uint32_t getK() { return k_; }
+
+  /**
+   * Clear source block
+   */
+  void clear();
+
+ private:
+  /**
+   * Add symbol to source block
+   **/
+  bool addSymbol(const fec::buffer &packet, uint32_t i, std::size_t size);
+
+  /**
+   * Starting from k source symbols, get the n - k repair symbols
+   */
+  void encode();
+
+  /**
+   * Starting from k symbols (mixed repair and source), get k source symbols.
+   * NOTE: It does not make sense to retrieve the k source symbols using the
+   * very same k source symbols. With the current implementation that case can
+   * never happen.
+   */
+  void decode();
+
+ private:
+  uint32_t k_;
+  uint32_t n_;
+  struct fec_parms *code_;
+  std::size_t max_buffer_size_;
+  std::size_t current_block_size_;
+  std::vector<uint32_t> sorted_index_;
+  bool to_decode_;
+};
+
+/**
+ * This class contains common parameters between the fec encoder and decoder.
+ * In particular it contains:
+ *  - The callback to be called when symbols are encoded / decoded
+ *  - The reference to the static reed-solomon parameters, allocated at program
+ * startup
+ *  - N and K. Ideally they are useful only for the encoder (the decoder can
+ * retrieve them from the FEC header). However right now we assume sender and
+ * receiver agreed on the parameters k and n to use. We will introduce a control
+ * message later to negotiate them, so that decoder cah dynamically change them
+ * during the download.
+ */
+class rs {
+  /**
+   * Deleter for static preallocated reed-solomon parameters.
+   */
+  struct MatrixDeleter {
+    void operator()(struct fec_parms *params);
+  };
+
+  /**
+   * unique_ptr to reed-solomon parameters, with custom deleter to call fec_free
+   * at the end of the program
+   */
+  using Matrix = std::unique_ptr<struct fec_parms, MatrixDeleter>;
+
+  /**
+   * Key to retrieve static preallocated reed-solomon parameters. It is pair of
+   * k and n
+   */
+  using Code = std::pair<std::uint32_t /* k */, std::uint32_t /* n */>;
+
+  /**
+   * Custom hash function for (k, n) pair.
+   */
+  struct CodeHasher {
+    std::size_t operator()(const transport::core::fec::rs::Code &code) const {
+      uint64_t ret = uint64_t(code.first) << 32 | uint64_t(code.second);
+      return std::hash<uint64_t>{}(ret);
+    }
+  };
+
+ protected:
+  /**
+   * Callback to be called after the encode or the decode operations. In the
+   * former case it will contain the symbols, while in the latter the sources.
+   */
+  using PacketsReady = std::function<void(std::vector<buffer> &)>;
+
+  /**
+   * The sequence number base.
+   */
+  using SNBase = std::uint32_t;
+
+  /**
+   * The map of source blocks, used at the decoder side. For the encoding
+   * operation we can use one source block only, since packet are produced in
+   * order.
+   */
+  using SourceBlocks = std::unordered_map<SNBase, BlockCode>;
+
+  /**
+   * Map (k, n) -> reed-solomon parameter
+   */
+  using Codes = std::unordered_map<Code, Matrix, CodeHasher>;
+
+ public:
+  rs(uint32_t k, uint32_t n);
+  ~rs() = default;
+
+  /**
+   * Set callback to call after packet encoding / decoding
+   */
+  void setFECCallback(const PacketsReady &callback);
+
+  virtual void clear() { processed_source_blocks_.clear(); }
+
+ private:
+  /**
+   * Create reed-solomon codes at program startup.
+   */
+  static Codes createCodes();
+
+ protected:
+  bool processed(SNBase seq_base) {
+    return processed_source_blocks_.find(seq_base) !=
+           processed_source_blocks_.end();
+  }
+
+  std::uint32_t k_;
+  std::uint32_t n_;
+  PacketsReady fec_callback_;
+
+  /**
+   * Keep track of processed source blocks
+   */
+  std::unordered_set<SNBase> processed_source_blocks_;
+
+  static Codes codes_;
+};
+
+/**
+ * The reed-solomon encoder. It is feeded with source symbols and it provide
+ * repair-symbols through the fec_callback_
+ */
+class encoder : public rs {
+ public:
+  encoder(uint32_t k, uint32_t n);
+  /**
+   * Always consume source symbols.
+   */
+  void consume(const fec::buffer &packet, uint32_t index);
+
+  void clear() override {
+    rs::clear();
+    source_block_.clear();
+  }
+
+ private:
+  struct fec_parms *current_code_;
+  /**
+   * The source block. As soon as it is filled with k source symbols, the
+   * encoder calls the callback fec_callback_ and the resets the block 0, ready
+   * to accept another batch of k source symbols.
+   */
+  BlockCode source_block_;
+};
+
+/**
+ * The reed-solomon encoder. It is feeded with source/repair symbols and it
+ * provides the original source symbols through the fec_callback_
+ */
+class decoder : public rs {
+ public:
+  decoder(uint32_t k, uint32_t n);
+
+  /**
+   * Consume source symbol
+   */
+  void consume(const fec::buffer &packet, uint32_t i);
+
+  /**
+   * Consume repair symbol
+   */
+  void consume(const fec::buffer &packet);
+
+  /**
+   * Clear decoder to reuse
+   */
+  void clear() override {
+    rs::clear();
+    src_blocks_.clear();
+    parked_packets_.clear();
+  }
+
+ private:
+  void recoverPackets(SourceBlocks::iterator &src_block_it);
+
+ private:
+  /**
+   * Map of source blocks. We use a map because we may receive symbols belonging
+   * to diffreent source blocks at the same time, so we need to be able to
+   * decode many source symbols at the same time.
+   */
+  SourceBlocks src_blocks_;
+
+  /**
+   * Unordered Map of source symbols for which we did not receive any repair
+   * symbol in the same source block. Notably this happens when:
+   *
+   * - We receive the source symbols first and the repair symbols after
+   * - We received only source symbols for a given block. In that case it does
+   * not make any sense to build the source block, since we received all the
+   * source packet of the block.
+   */
+  std::unordered_map<uint32_t, std::vector<std::pair<buffer, uint32_t>>>
+      parked_packets_;
+};
+
+}  // namespace fec
+
+}  // namespace core
+
+}  // namespace transport