[HICN-713] Transport Library Major Refactoring 2

Co-authored-by: Luca Muscariello <muscariello@ieee.org>
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>
Signed-off-by: Mauro Sardara <msardara@cisco.com>
Change-Id: I5b2c667bad66feb45abdb5effe22ed0f6c85d1c2

8 files changed, 2224 insertions, 0 deletions

diff --git a/libtransport/src/protocols/fec/CMakeLists.txt b/libtransport/src/protocols/fec/CMakeLists.txt
new file mode 100644
index 000000000..6d61ae043
--- /dev/null
+++ b/libtransport/src/protocols/fec/CMakeLists.txt
@@ -0,0 +1,36 @@
+# Copyright (c) 2017-2019 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.
+
+list(APPEND HEADER_FILES
+  ${CMAKE_CURRENT_SOURCE_DIR}/fec.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/rs.h
+  ${CMAKE_CURRENT_SOURCE_DIR}/fec_info.h
+)
+
+list(APPEND SOURCE_FILES
+  ${CMAKE_CURRENT_SOURCE_DIR}/fec.cc
+  ${CMAKE_CURRENT_SOURCE_DIR}/rs.cc
+)
+
+if (ENABLE_RELY)
+  list(APPEND HEADER_FILES
+    ${CMAKE_CURRENT_SOURCE_DIR}/rely.h
+  )
+
+  list(APPEND SOURCE_FILES
+    ${CMAKE_CURRENT_SOURCE_DIR}/rely.cc
+  )
+endif()
+
+set(SOURCE_FILES ${SOURCE_FILES} PARENT_SCOPE)
+set(HEADER_FILES ${HEADER_FILES} PARENT_SCOPE)
diff --git a/libtransport/src/protocols/fec/fec.cc b/libtransport/src/protocols/fec/fec.cc
new file mode 100644
index 000000000..16a04cb98
--- /dev/null
+++ b/libtransport/src/protocols/fec/fec.cc
@@ -0,0 +1,838 @@
+/*
+ * fec.c -- forward error correction based on Vandermonde matrices
+ * 980624
+ * (C) 1997-98 Luigi Rizzo (luigi@iet.unipi.it)
+ *
+ * Portions derived from code by Phil Karn (karn@ka9q.ampr.org),
+ * Robert Morelos-Zaragoza (robert@spectra.eng.hawaii.edu) and Hari
+ * Thirumoorthy (harit@spectra.eng.hawaii.edu), Aug 1995
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above
+ *    copyright notice, this list of conditions and the following
+ *    disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+ * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+ * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ */
+
+/*
+ * The following parameter defines how many bits are used for
+ * field elements. The code supports any value from 2 to 16
+ * but fastest operation is achieved with 8 bit elements
+ * This is the only parameter you may want to change.
+ */
+#ifndef GF_BITS
+#define GF_BITS 8 /* code over GF(2**GF_BITS) - change to suit */
+#endif
+
+#include "fec.h"
+
+#include <hicn/transport/portability/platform.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/**
+ * XXX This disable a warning raising only in some platforms.
+ * TODO Check if this warning is a mistake or it is a real bug:
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83404
+ * https://gcc.gnu.org/bugzilla//show_bug.cgi?id=88059
+ */
+#ifndef __clang__
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+#endif
+
+/*
+ * compatibility stuff
+ */
+#ifdef MSDOS /* but also for others, e.g. sun... */
+#define NEED_BCOPY
+#define bcmp(a, b, n) memcmp(a, b, n)
+#endif
+
+#ifdef ANDROID
+#define bcmp(a, b, n) memcmp(a, b, n)
+#endif
+
+#ifdef NEED_BCOPY
+#define bcopy(s, d, siz) memcpy((d), (s), (siz))
+#define bzero(d, siz) memset((d), '\0', (siz))
+#endif
+
+/*
+ * stuff used for testing purposes only
+ */
+
+#ifdef TEST
+#define DEB(x)
+#define DDB(x) x
+#define DEBUG 0 /* minimal debugging */
+#ifdef MSDOS
+#include <time.h>
+struct timeval {
+  unsigned long ticks;
+};
+#define gettimeofday(x, dummy) \
+  { (x)->ticks = clock(); }
+#define DIFF_T(a, b) (1 + 1000000 * (a.ticks - b.ticks) / CLOCKS_PER_SEC)
+typedef unsigned long u_long;
+typedef unsigned short u_short;
+#else /* typically, unix systems */
+#include <sys/time.h>
+#define DIFF_T(a, b) \
+  (1 + 1000000 * (a.tv_sec - b.tv_sec) + (a.tv_usec - b.tv_usec))
+#endif
+
+#define TICK(t)                                  \
+  {                                              \
+    struct timeval x;                            \
+    gettimeofday(&x, NULL);                      \
+    t = x.tv_usec + 1000000 * (x.tv_sec & 0xff); \
+  }
+#define TOCK(t)               \
+  {                           \
+    u_long t1;                \
+    TICK(t1);                 \
+    if (t1 < t)               \
+      t = 256000000 + t1 - t; \
+    else                      \
+      t = t1 - t;             \
+    if (t == 0) t = 1;        \
+  }
+
+u_long ticks[10]; /* vars for timekeeping */
+#else
+#define DEB(x)
+#define DDB(x)
+#define TICK(x)
+#define TOCK(x)
+#endif /* TEST */
+
+/*
+ * You should not need to change anything beyond this point.
+ * The first part of the file implements linear algebra in GF.
+ *
+ * gf is the type used to store an element of the Galois Field.
+ * Must constain at least GF_BITS bits.
+ *
+ * Note: unsigned char will work up to GF(256) but int seems to run
+ * faster on the Pentium. We use int whenever have to deal with an
+ * index, since they are generally faster.
+ */
+#if (GF_BITS < 2 && GF_BITS > 16)
+#error "GF_BITS must be 2 .. 16"
+#endif
+
+#define GF_SIZE ((1 << GF_BITS) - 1) /* powers of \alpha */
+
+/*
+ * Primitive polynomials - see Lin & Costello, Appendix A,
+ * and  Lee & Messerschmitt, p. 453.
+ */
+static const char *allPp[] = {
+    /* GF_BITS	polynomial		*/
+    NULL,               /*  0	no code			*/
+    NULL,               /*  1	no code			*/
+    "111",              /*  2	1+x+x^2			*/
+    "1101",             /*  3	1+x+x^3			*/
+    "11001",            /*  4	1+x+x^4			*/
+    "101001",           /*  5	1+x^2+x^5		*/
+    "1100001",          /*  6	1+x+x^6			*/
+    "10010001",         /*  7	1 + x^3 + x^7		*/
+    "101110001",        /*  8	1+x^2+x^3+x^4+x^8	*/
+    "1000100001",       /*  9	1+x^4+x^9		*/
+    "10010000001",      /* 10	1+x^3+x^10		*/
+    "101000000001",     /* 11	1+x^2+x^11		*/
+    "1100101000001",    /* 12	1+x+x^4+x^6+x^12	*/
+    "11011000000001",   /* 13	1+x+x^3+x^4+x^13	*/
+    "110000100010001",  /* 14	1+x+x^6+x^10+x^14	*/
+    "1100000000000001", /* 15	1+x+x^15		*/
+    "11010000000010001" /* 16	1+x+x^3+x^12+x^16	*/
+};
+
+/*
+ * To speed up computations, we have tables for logarithm, exponent
+ * and inverse of a number. If GF_BITS <= 8, we use a table for
+ * multiplication as well (it takes 64K, no big deal even on a PDA,
+ * especially because it can be pre-initialized an put into a ROM!),
+ * otherwhise we use a table of logarithms.
+ * In any case the macro gf_mul(x,y) takes care of multiplications.
+ */
+
+static gf gf_exp[2 * GF_SIZE];  /* index->poly form conversion table	*/
+static int gf_log[GF_SIZE + 1]; /* Poly->index form conversion table	*/
+static gf inverse[GF_SIZE + 1]; /* inverse of field elem.		*/
+                                /* inv[\alpha**i]=\alpha**(GF_SIZE-i-1)	*/
+
+/*
+ * modnn(x) computes x % GF_SIZE, where GF_SIZE is 2**GF_BITS - 1,
+ * without a slow divide.
+ */
+static inline gf modnn(int x) {
+  while (x >= GF_SIZE) {
+    x -= GF_SIZE;
+    x = (x >> GF_BITS) + (x & GF_SIZE);
+  }
+  return x;
+}
+
+#define SWAP(a, b, t) \
+  {                   \
+    t tmp;            \
+    tmp = a;          \
+    a = b;            \
+    b = tmp;          \
+  }
+
+/*
+ * gf_mul(x,y) multiplies two numbers. If GF_BITS<=8, it is much
+ * faster to use a multiplication table.
+ *
+ * USE_GF_MULC, GF_MULC0(c) and GF_ADDMULC(x) can be used when multiplying
+ * many numbers by the same constant. In this case the first
+ * call sets the constant, and others perform the multiplications.
+ * A value related to the multiplication is held in a local variable
+ * declared with USE_GF_MULC . See usage in addmul1().
+ */
+#if (GF_BITS <= 8)
+static gf gf_mul_table[GF_SIZE + 1][GF_SIZE + 1];
+
+#define gf_mul(x, y) gf_mul_table[x][y]
+
+#define USE_GF_MULC gf *__gf_mulc_
+#define GF_MULC0(c) __gf_mulc_ = gf_mul_table[c]
+#define GF_ADDMULC(dst, x) dst ^= __gf_mulc_[x]
+
+static void init_mul_table() {
+  int i, j;
+  for (i = 0; i < GF_SIZE + 1; i++)
+    for (j = 0; j < GF_SIZE + 1; j++)
+      gf_mul_table[i][j] = gf_exp[modnn(gf_log[i] + gf_log[j])];
+
+  for (j = 0; j < GF_SIZE + 1; j++) gf_mul_table[0][j] = gf_mul_table[j][0] = 0;
+}
+#else /* GF_BITS > 8 */
+static inline gf gf_mul(x, y) {
+  if ((x) == 0 || (y) == 0) return 0;
+
+  return gf_exp[gf_log[x] + gf_log[y]];
+}
+#define init_mul_table()
+
+#define USE_GF_MULC register gf *__gf_mulc_
+#define GF_MULC0(c) __gf_mulc_ = &gf_exp[gf_log[c]]
+#define GF_ADDMULC(dst, x)               \
+  {                                      \
+    if (x) dst ^= __gf_mulc_[gf_log[x]]; \
+  }
+#endif
+
+/*
+ * Generate GF(2**m) from the irreducible polynomial p(X) in p[0]..p[m]
+ * Lookup tables:
+ *     index->polynomial form		gf_exp[] contains j= \alpha^i;
+ *     polynomial form -> index form	gf_log[ j = \alpha^i ] = i
+ * \alpha=x is the primitive element of GF(2^m)
+ *
+ * For efficiency, gf_exp[] has size 2*GF_SIZE, so that a simple
+ * multiplication of two numbers can be resolved without calling modnn
+ */
+
+/*
+ * i use malloc so many times, it is easier to put checks all in
+ * one place.
+ */
+static void *my_malloc(int sz, const char *err_string) {
+  void *p = malloc(sz);
+  if (p == NULL) {
+    fprintf(stderr, "-- malloc failure allocating %s\n", err_string);
+    exit(1);
+  }
+  return p;
+}
+
+#define NEW_GF_MATRIX(rows, cols) \
+  (gf *)my_malloc(rows *cols * sizeof(gf), " ## __LINE__ ## ")
+
+/*
+ * initialize the data structures used for computations in GF.
+ */
+static void generate_gf(void) {
+  int i;
+  gf mask;
+  const char *Pp = allPp[GF_BITS];
+
+  mask = 1;            /* x ** 0 = 1 */
+  gf_exp[GF_BITS] = 0; /* will be updated at the end of the 1st loop */
+  /*
+   * first, generate the (polynomial representation of) powers of \alpha,
+   * which are stored in gf_exp[i] = \alpha ** i .
+   * At the same time build gf_log[gf_exp[i]] = i .
+   * The first GF_BITS powers are simply bits shifted to the left.
+   */
+  for (i = 0; i < GF_BITS; i++, mask <<= 1) {
+    gf_exp[i] = mask;
+    gf_log[gf_exp[i]] = i;
+    /*
+     * If Pp[i] == 1 then \alpha ** i occurs in poly-repr
+     * gf_exp[GF_BITS] = \alpha ** GF_BITS
+     */
+    if (Pp[i] == '1') gf_exp[GF_BITS] ^= mask;
+  }
+  /*
+   * now gf_exp[GF_BITS] = \alpha ** GF_BITS is complete, so can als
+   * compute its inverse.
+   */
+  gf_log[gf_exp[GF_BITS]] = GF_BITS;
+  /*
+   * Poly-repr of \alpha ** (i+1) is given by poly-repr of
+   * \alpha ** i shifted left one-bit and accounting for any
+   * \alpha ** GF_BITS term that may occur when poly-repr of
+   * \alpha ** i is shifted.
+   */
+  mask = 1 << (GF_BITS - 1);
+  for (i = GF_BITS + 1; i < GF_SIZE; i++) {
+    if (gf_exp[i - 1] >= mask)
+      gf_exp[i] = gf_exp[GF_BITS] ^ ((gf_exp[i - 1] ^ mask) << 1);
+    else
+      gf_exp[i] = gf_exp[i - 1] << 1;
+    gf_log[gf_exp[i]] = i;
+  }
+  /*
+   * log(0) is not defined, so use a special value
+   */
+  gf_log[0] = GF_SIZE;
+  /* set the extended gf_exp values for fast multiply */
+  for (i = 0; i < GF_SIZE; i++) gf_exp[i + GF_SIZE] = gf_exp[i];
+
+  /*
+   * again special cases. 0 has no inverse. This used to
+   * be initialized to GF_SIZE, but it should make no difference
+   * since noone is supposed to read from here.
+   */
+  inverse[0] = 0;
+  inverse[1] = 1;
+  for (i = 2; i <= GF_SIZE; i++) inverse[i] = gf_exp[GF_SIZE - gf_log[i]];
+}
+
+/*
+ * Various linear algebra operations that i use often.
+ */
+
+/*
+ * addmul() computes dst[] = dst[] + c * src[]
+ * This is used often, so better optimize it! Currently the loop is
+ * unrolled 16 times, a good value for 486 and pentium-class machines.
+ * The case c=0 is also optimized, whereas c=1 is not. These
+ * calls are unfrequent in my typical apps so I did not bother.
+ *
+ * Note that gcc on
+ */
+#define addmul(dst, src, c, sz) \
+  if (c != 0) addmul1(dst, src, c, sz)
+
+#define UNROLL 16 /* 1, 4, 8, 16 */
+static void addmul1(gf *dst1, gf *src1, gf c, int sz) {
+  USE_GF_MULC;
+  gf *dst = dst1, *src = src1;
+  gf *lim = &dst[sz - UNROLL + 1];
+
+  GF_MULC0(c);
+
+#if (UNROLL > 1) /* unrolling by 8/16 is quite effective on the pentium */
+  for (; dst < lim; dst += UNROLL, src += UNROLL) {
+    GF_ADDMULC(dst[0], src[0]);
+    GF_ADDMULC(dst[1], src[1]);
+    GF_ADDMULC(dst[2], src[2]);
+    GF_ADDMULC(dst[3], src[3]);
+#if (UNROLL > 4)
+    GF_ADDMULC(dst[4], src[4]);
+    GF_ADDMULC(dst[5], src[5]);
+    GF_ADDMULC(dst[6], src[6]);
+    GF_ADDMULC(dst[7], src[7]);
+#endif
+#if (UNROLL > 8)
+    GF_ADDMULC(dst[8], src[8]);
+    GF_ADDMULC(dst[9], src[9]);
+    GF_ADDMULC(dst[10], src[10]);
+    GF_ADDMULC(dst[11], src[11]);
+    GF_ADDMULC(dst[12], src[12]);
+    GF_ADDMULC(dst[13], src[13]);
+    GF_ADDMULC(dst[14], src[14]);
+    GF_ADDMULC(dst[15], src[15]);
+#endif
+  }
+#endif
+  lim += UNROLL - 1;
+  for (; dst < lim; dst++, src++) /* final components */
+    GF_ADDMULC(*dst, *src);
+}
+
+/*
+ * computes C = AB where A is n*k, B is k*m, C is n*m
+ */
+static void matmul(gf *a, gf *b, gf *c, int n, int k, int m) {
+  int row, col, i;
+
+  for (row = 0; row < n; row++) {
+    for (col = 0; col < m; col++) {
+      gf *pa = &a[row * k];
+      gf *pb = &b[col];
+      gf acc = 0;
+      for (i = 0; i < k; i++, pa++, pb += m) acc ^= gf_mul(*pa, *pb);
+      c[row * m + col] = acc;
+    }
+  }
+}
+
+#ifdef DEBUGG
+/*
+ * returns 1 if the square matrix is identiy
+ * (only for test)
+ */
+static int is_identity(gf *m, int k) {
+  int row, col;
+  for (row = 0; row < k; row++)
+    for (col = 0; col < k; col++)
+      if ((row == col && *m != 1) || (row != col && *m != 0))
+        return 0;
+      else
+        m++;
+  return 1;
+}
+#endif /* debug */
+
+/*
+ * invert_mat() takes a matrix and produces its inverse
+ * k is the size of the matrix.
+ * (Gauss-Jordan, adapted from Numerical Recipes in C)
+ * Return non-zero if singular.
+ */
+DEB(int pivloops = 0; int pivswaps = 0; /* diagnostic */)
+static int invert_mat(gf *src, int k) {
+  gf c, *p;
+  int irow, icol, row, col, i, ix;
+
+  int error = 1;
+  int *indxc = (int *)my_malloc(k * sizeof(int), "indxc");
+  int *indxr = (int *)my_malloc(k * sizeof(int), "indxr");
+  int *ipiv = (int *)my_malloc(k * sizeof(int), "ipiv");
+  gf *id_row = NEW_GF_MATRIX(1, k);
+  gf *temp_row = NEW_GF_MATRIX(1, k);
+
+  bzero(id_row, k * sizeof(gf));
+  DEB(pivloops = 0; pivswaps = 0; /* diagnostic */)
+  /*
+   * ipiv marks elements already used as pivots.
+   */
+  for (i = 0; i < k; i++) ipiv[i] = 0;
+
+  for (col = 0; col < k; col++) {
+    gf *pivot_row;
+    /*
+     * Zeroing column 'col', look for a non-zero element.
+     * First try on the diagonal, if it fails, look elsewhere.
+     */
+    irow = icol = -1;
+    if (ipiv[col] != 1 && src[col * k + col] != 0) {
+      irow = col;
+      icol = col;
+      goto found_piv;
+    }
+    for (row = 0; row < k; row++) {
+      if (ipiv[row] != 1) {
+        for (ix = 0; ix < k; ix++) {
+          DEB(pivloops++;)
+          if (ipiv[ix] == 0) {
+            if (src[row * k + ix] != 0) {
+              irow = row;
+              icol = ix;
+              goto found_piv;
+            }
+          } else if (ipiv[ix] > 1) {
+            fprintf(stderr, "singular matrix\n");
+            goto fail;
+          }
+        }
+      }
+    }
+    if (icol == -1) {
+      fprintf(stderr, "XXX pivot not found!\n");
+      goto fail;
+    }
+  found_piv:
+    ++(ipiv[icol]);
+    /*
+     * swap rows irow and icol, so afterwards the diagonal
+     * element will be correct. Rarely done, not worth
+     * optimizing.
+     */
+    if (irow != icol) {
+      for (ix = 0; ix < k; ix++) {
+        SWAP(src[irow * k + ix], src[icol * k + ix], gf);
+      }
+    }
+    indxr[col] = irow;
+    indxc[col] = icol;
+    pivot_row = &src[icol * k];
+    c = pivot_row[icol];
+    if (c == 0) {
+      fprintf(stderr, "singular matrix 2\n");
+      goto fail;
+    }
+    if (c != 1) { /* otherwhise this is a NOP */
+      /*
+       * this is done often , but optimizing is not so
+       * fruitful, at least in the obvious ways (unrolling)
+       */
+      DEB(pivswaps++;)
+      c = inverse[c];
+      pivot_row[icol] = 1;
+      for (ix = 0; ix < k; ix++) pivot_row[ix] = gf_mul(c, pivot_row[ix]);
+    }
+    /*
+     * from all rows, remove multiples of the selected row
+     * to zero the relevant entry (in fact, the entry is not zero
+     * because we know it must be zero).
+     * (Here, if we know that the pivot_row is the identity,
+     * we can optimize the addmul).
+     */
+    id_row[icol] = 1;
+    if (bcmp(pivot_row, id_row, k * sizeof(gf)) != 0) {
+      for (p = src, ix = 0; ix < k; ix++, p += k) {
+        if (ix != icol) {
+          c = p[icol];
+          p[icol] = 0;
+          addmul(p, pivot_row, c, k);
+        }
+      }
+    }
+    id_row[icol] = 0;
+  } /* done all columns */
+  for (col = k - 1; col >= 0; col--) {
+    if (indxr[col] < 0 || indxr[col] >= k)
+      fprintf(stderr, "AARGH, indxr[col] %d\n", indxr[col]);
+    else if (indxc[col] < 0 || indxc[col] >= k)
+      fprintf(stderr, "AARGH, indxc[col] %d\n", indxc[col]);
+    else if (indxr[col] != indxc[col]) {
+      for (row = 0; row < k; row++) {
+        SWAP(src[row * k + indxr[col]], src[row * k + indxc[col]], gf);
+      }
+    }
+  }
+  error = 0;
+fail:
+  free(indxc);
+  free(indxr);
+  free(ipiv);
+  free(id_row);
+  free(temp_row);
+  return error;
+}
+
+/*
+ * fast code for inverting a vandermonde matrix.
+ * XXX NOTE: It assumes that the matrix
+ * is not singular and _IS_ a vandermonde matrix. Only uses
+ * the second column of the matrix, containing the p_i's.
+ *
+ * Algorithm borrowed from "Numerical recipes in C" -- sec.2.8, but
+ * largely revised for my purposes.
+ * p = coefficients of the matrix (p_i)
+ * q = values of the polynomial (known)
+ */
+
+int invert_vdm(gf *src, int k) {
+  int i, j, row, col;
+  gf *b, *c, *p;
+  gf t, xx;
+
+  if (k == 1) /* degenerate case, matrix must be p^0 = 1 */
+    return 0;
+  /*
+   * c holds the coefficient of P(x) = Prod (x - p_i), i=0..k-1
+   * b holds the coefficient for the matrix inversion
+   */
+  c = NEW_GF_MATRIX(1, k);
+  b = NEW_GF_MATRIX(1, k);
+
+  p = NEW_GF_MATRIX(1, k);
+
+  for (j = 1, i = 0; i < k; i++, j += k) {
+    c[i] = 0;
+    p[i] = src[j]; /* p[i] */
+  }
+  /*
+   * construct coeffs. recursively. We know c[k] = 1 (implicit)
+   * and start P_0 = x - p_0, then at each stage multiply by
+   * x - p_i generating P_i = x P_{i-1} - p_i P_{i-1}
+   * After k steps we are done.
+   */
+  c[k - 1] = p[0]; /* really -p(0), but x = -x in GF(2^m) */
+  for (i = 1; i < k; i++) {
+    gf p_i = p[i]; /* see above comment */
+    for (j = k - 1 - (i - 1); j < k - 1; j++) c[j] ^= gf_mul(p_i, c[j + 1]);
+    c[k - 1] ^= p_i;
+  }
+
+  for (row = 0; row < k; row++) {
+    /*
+     * synthetic division etc.
+     */
+    xx = p[row];
+    t = 1;
+    b[k - 1] = 1; /* this is in fact c[k] */
+    for (i = k - 2; i >= 0; i--) {
+      b[i] = c[i + 1] ^ gf_mul(xx, b[i + 1]);
+      t = gf_mul(xx, t) ^ b[i];
+    }
+    for (col = 0; col < k; col++)
+      src[col * k + row] = gf_mul(inverse[t], b[col]);
+  }
+  free(c);
+  free(b);
+  free(p);
+  return 0;
+}
+
+static int fec_initialized = 0;
+static void init_fec() {
+  TICK(ticks[0]);
+  generate_gf();
+  TOCK(ticks[0]);
+  DDB(fprintf(stderr, "generate_gf took %ldus\n", ticks[0]);)
+  TICK(ticks[0]);
+  init_mul_table();
+  TOCK(ticks[0]);
+  DDB(fprintf(stderr, "init_mul_table took %ldus\n", ticks[0]);)
+  fec_initialized = 1;
+}
+
+/*
+ * This section contains the proper FEC encoding/decoding routines.
+ * The encoding matrix is computed starting with a Vandermonde matrix,
+ * and then transforming it into a systematic matrix.
+ */
+
+#define FEC_MAGIC 0xFECC0DEC
+
+void fec_free(struct fec_parms *p) {
+  if (p == NULL || p->magic != (((FEC_MAGIC ^ p->k) ^ p->n) ^
+                                (unsigned long)(p->enc_matrix))) {
+    fprintf(stderr, "bad parameters to fec_free\n");
+    return;
+  }
+  free(p->enc_matrix);
+  free(p);
+}
+
+/*
+ * create a new encoder, returning a descriptor. This contains k,n and
+ * the encoding matrix.
+ */
+struct fec_parms *fec_new(int k, int n) {
+  int row, col;
+  gf *p, *tmp_m;
+
+  struct fec_parms *retval;
+
+  if (fec_initialized == 0) init_fec();
+
+  if (k > GF_SIZE + 1 || n > GF_SIZE + 1 || k > n) {
+    fprintf(stderr, "Invalid parameters k %d n %d GF_SIZE %d\n", k, n, GF_SIZE);
+    return NULL;
+  }
+  retval = (struct fec_parms *)my_malloc(sizeof(struct fec_parms), "new_code");
+  retval->k = k;
+  retval->n = n;
+  retval->enc_matrix = NEW_GF_MATRIX(n, k);
+  retval->magic = ((FEC_MAGIC ^ k) ^ n) ^ (unsigned long)(retval->enc_matrix);
+  tmp_m = NEW_GF_MATRIX(n, k);
+  /*
+   * fill the matrix with powers of field elements, starting from 0.
+   * The first row is special, cannot be computed with exp. table.
+   */
+  tmp_m[0] = 1;
+  for (col = 1; col < k; col++) tmp_m[col] = 0;
+  for (p = tmp_m + k, row = 0; row < n - 1; row++, p += k) {
+    for (col = 0; col < k; col++) p[col] = gf_exp[modnn(row * col)];
+  }
+
+  /*
+   * quick code to build systematic matrix: invert the top
+   * k*k vandermonde matrix, multiply right the bottom n-k rows
+   * by the inverse, and construct the identity matrix at the top.
+   */
+  TICK(ticks[3]);
+  invert_vdm(tmp_m, k); /* much faster than invert_mat */
+  matmul(tmp_m + k * k, tmp_m, retval->enc_matrix + k * k, n - k, k, k);
+  /*
+   * the upper matrix is I so do not bother with a slow multiply
+   */
+  bzero(retval->enc_matrix, k * k * sizeof(gf));
+  for (p = retval->enc_matrix, col = 0; col < k; col++, p += k + 1) *p = 1;
+  free(tmp_m);
+  TOCK(ticks[3]);
+
+  DDB(fprintf(stderr, "--- %ld us to build encoding matrix\n", ticks[3]);)
+  DEB(pr_matrix(retval->enc_matrix, n, k, "encoding_matrix");)
+  return retval;
+}
+
+/*
+ * fec_encode accepts as input pointers to n data packets of size sz,
+ * and produces as output a packet pointed to by fec, computed
+ * with index "index".
+ */
+void fec_encode(struct fec_parms *code, gf *src[], gf *fec, int index, int sz) {
+  int i, k = code->k;
+  gf *p;
+
+  if (GF_BITS > 8) sz /= 2;
+
+  if (index < k)
+    bcopy(src[index], fec, sz * sizeof(gf));
+  else if (index < code->n) {
+    p = &(code->enc_matrix[index * k]);
+    bzero(fec, sz * sizeof(gf));
+    for (i = 0; i < k; i++) addmul(fec, src[i], p[i], sz);
+  } else
+    fprintf(stderr, "Invalid index %d (max %d)\n", index, code->n - 1);
+}
+
+/*
+ * shuffle move src packets in their position
+ */
+static int shuffle(gf *pkt[], int index[], int k) {
+  int i;
+
+  for (i = 0; i < k;) {
+    if (index[i] >= k || index[i] == i)
+      i++;
+    else {
+      /*
+       * put pkt in the right position (first check for conflicts).
+       */
+      int c = index[i];
+
+      if (index[c] == c) {
+        DEB(fprintf(stderr, "\nshuffle, error at %d\n", i);)
+        return 1;
+      }
+      SWAP(index[i], index[c], int);
+      SWAP(pkt[i], pkt[c], gf *);
+    }
+  }
+  DEB(/* just test that it works... */
+      for (i = 0; i < k; i++) {
+        if (index[i] < k && index[i] != i) {
+          fprintf(stderr, "shuffle: after\n");
+          for (i = 0; i < k; i++) fprintf(stderr, "%3d ", index[i]);
+          fprintf(stderr, "\n");
+          return 1;
+        }
+      })
+  return 0;
+}
+
+/*
+ * build_decode_matrix constructs the encoding matrix given the
+ * indexes. The matrix must be already allocated as
+ * a vector of k*k elements, in row-major order
+ */
+static gf *build_decode_matrix(struct fec_parms *code, gf *pkt[], int index[]) {
+  int i, k = code->k;
+  gf *p, *matrix = NEW_GF_MATRIX(k, k);
+
+  TICK(ticks[9]);
+  for (i = 0, p = matrix; i < k; i++, p += k) {
+#if 1 /* this is simply an optimization, not very useful indeed */
+    if (index[i] < k) {
+      bzero(p, k * sizeof(gf));
+      p[i] = 1;
+    } else
+#endif
+        if (index[i] < code->n)
+      bcopy(&(code->enc_matrix[index[i] * k]), p, k * sizeof(gf));
+    else {
+      fprintf(stderr, "decode: invalid index %d (max %d)\n", index[i],
+              code->n - 1);
+      free(matrix);
+      return NULL;
+    }
+  }
+  TICK(ticks[9]);
+  if (invert_mat(matrix, k)) {
+    free(matrix);
+    matrix = NULL;
+  }
+  TOCK(ticks[9]);
+  return matrix;
+}
+
+/*
+ * fec_decode receives as input a vector of packets, the indexes of
+ * packets, and produces the correct vector as output.
+ *
+ * Input:
+ *	code: pointer to code descriptor
+ *	pkt:  pointers to received packets. They are modified
+ *	      to store the output packets (in place)
+ *	index: pointer to packet indexes (modified)
+ *	sz:    size of each packet
+ */
+int fec_decode(struct fec_parms *code, gf *pkt[], int index[], int sz) {
+  gf *m_dec;
+  gf **new_pkt;
+  int row, col, k = code->k;
+
+  if (GF_BITS > 8) sz /= 2;
+
+  if (shuffle(pkt, index, k)) /* error if true */
+    return 1;
+  m_dec = build_decode_matrix(code, pkt, index);
+
+  if (m_dec == NULL) return 1; /* error */
+  /*
+   * do the actual decoding
+   */
+  new_pkt = (gf **)my_malloc(k * sizeof(gf *), "new pkt pointers");
+  for (row = 0; row < k; row++) {
+    if (index[row] >= k) {
+      new_pkt[row] = (gf *)my_malloc(sz * sizeof(gf), "new pkt buffer");
+      bzero(new_pkt[row], sz * sizeof(gf));
+      for (col = 0; col < k; col++)
+        addmul(new_pkt[row], pkt[col], m_dec[row * k + col], sz);
+    }
+  }
+  /*
+   * move pkts to their final destination
+   */
+  for (row = 0; row < k; row++) {
+    if (index[row] >= k) {
+      bcopy(new_pkt[row], pkt[row], sz * sizeof(gf));
+      free(new_pkt[row]);
+    }
+  }
+  free(new_pkt);
+  free(m_dec);
+
+  return 0;
+}
diff --git a/libtransport/src/protocols/fec/fec.h b/libtransport/src/protocols/fec/fec.h
new file mode 100644
index 000000000..7710bb7af
--- /dev/null
+++ b/libtransport/src/protocols/fec/fec.h
@@ -0,0 +1,65 @@
+/*
+ * fec.c -- forward error correction based on Vandermonde matrices
+ * 980614
+ * (C) 1997-98 Luigi Rizzo (luigi@iet.unipi.it)
+ *
+ * Portions derived from code by Phil Karn (karn@ka9q.ampr.org),
+ * Robert Morelos-Zaragoza (robert@spectra.eng.hawaii.edu) and Hari
+ * Thirumoorthy (harit@spectra.eng.hawaii.edu), Aug 1995
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above
+ *    copyright notice, this list of conditions and the following
+ *    disclaimer in the documentation and/or other materials
+ *    provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+ * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+ * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ */
+
+/*
+ * The following parameter defines how many bits are used for
+ * field elements. The code supports any value from 2 to 16
+ * but fastest operation is achieved with 8 bit elements
+ * This is the only parameter you may want to change.
+ */
+#ifndef GF_BITS
+#define GF_BITS 8 /* code over GF(2**GF_BITS) - change to suit */
+#endif
+
+#if (GF_BITS <= 8)
+typedef unsigned char gf;
+#else
+typedef unsigned short gf;
+#endif
+
+#define GF_SIZE ((1 << GF_BITS) - 1) /* powers of \alpha */
+
+struct fec_parms {
+  unsigned long magic;
+  int k, n; /* parameters of the code */
+  gf *enc_matrix;
+};
+
+void fec_free(struct fec_parms *p);
+struct fec_parms *fec_new(int k, int n);
+
+void fec_encode(struct fec_parms *code, gf *src[], gf *fec, int index, int sz);
+int fec_decode(struct fec_parms *code, gf *pkt[], int index[], int sz);
+
+/* end of file */
diff --git a/libtransport/src/protocols/fec/fec_info.h b/libtransport/src/protocols/fec/fec_info.h
new file mode 100644
index 000000000..bdfc4d3af
--- /dev/null
+++ b/libtransport/src/protocols/fec/fec_info.h
@@ -0,0 +1,62 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <hicn/transport/errors/not_implemented_exception.h>
+
+namespace transport {
+namespace protocol {
+
+namespace fec {
+
+template <typename T>
+struct FecInfo {
+  static bool isFec() { throw errors::NotImplementedException(); }
+  static uint32_t nextSymbol(uint32_t index) {
+    throw errors::NotImplementedException();
+  }
+  static uint32_t nextSource(uint32_t index) {
+    throw errors::NotImplementedException();
+  }
+};
+
+template <uint32_t K, uint32_t N>
+struct Code {};
+
+template <uint32_t K, uint32_t N>
+struct FecInfo<Code<K, N>> {
+  static bool isFec(uint32_t index) { return (index % N) >= K; }
+
+  static uint32_t nextSymbol(uint32_t index) {
+    if (isFec(index)) {
+      return index;
+    }
+
+    return index + (K - (index % N));
+  }
+
+  static uint32_t nextSource(uint32_t index) {
+    if (!isFec(index)) {
+      return index;
+    }
+
+    return index + (N - (index % N));
+  }
+};
+
+}  // namespace fec
+}  // namespace protocol
+}  // namespace transport
\ No newline at end of file
diff --git a/libtransport/src/protocols/fec/rely.cc b/libtransport/src/protocols/fec/rely.cc
new file mode 100644
index 000000000..7a30a62e2
--- /dev/null
+++ b/libtransport/src/protocols/fec/rely.cc
@@ -0,0 +1,205 @@
+/*
+ * 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 <glog/logging.h>
+#include <hicn/transport/core/global_object_pool.h>
+#include <protocols/fec/rely.h>
+
+#include <rely/packet.hpp>
+
+namespace transport {
+namespace protocol {
+namespace fec {
+
+RelyEncoder::RelyEncoder(uint32_t k, uint32_t n, uint32_t seq_offset)
+    : RelyBase(k, n) {
+  configure(kmtu, ktimeout, kmax_stream_size);
+  set_repair_trigger(k_, n_ - k_, n_ - k_);
+}
+
+void RelyEncoder::onPacketProduced(core::ContentObject &content_object,
+                                   uint32_t offset) {
+  // Get pointer to payload, leaving space to insert FEC header.
+  // TODO Check if this additional header is really needed.
+  auto data = content_object.writableData() + offset - sizeof(fec_header);
+  auto length = content_object.length() - offset + sizeof(fec_header);
+
+  // Check packet length does not exceed maximum length supported by the
+  // encoder (otherwise segmentation would take place).
+  assert(length < max_packet_bytes());
+  DLOG_IF(INFO, VLOG_IS_ON(4))
+      << "Encoding packet of length " << length - sizeof(fec_header);
+
+  // Get the suffix. With rely we need to write it in the fec_header in order to
+  // be able to recognize the seq number upon recovery.
+  auto suffix = content_object.getName().getSuffix();
+  DLOG_IF(INFO, VLOG_IS_ON(4)) << "Producing packet " << suffix
+                               << " (index == " << current_index_ << ")";
+
+  // Consume payload. Add fec_header in front before feeding payload to encoder,
+  // and copy original content of packet
+  fec_header *h = reinterpret_cast<fec_header *>(data);
+  fec_header copy = *h;
+  h->setSeqNumberBase(suffix);
+  auto packets = consume(data, length, getCurrentTime());
+  assert(packets == 1);
+
+  // Update packet counter
+  current_index_ += packets;
+
+  // Restore original packet content and increment data pointer to the correct
+  // position
+  *h = copy;
+  data += sizeof(fec_header);
+
+  // Check position of this packet inside N size block
+  auto i = current_index_ % n_;
+
+  // encoder will produce a source packet
+  if (i <= k_) {
+    // Rely modifies the payload of the packet. We replace the packet with the
+    // one returned by rely.
+    // TODO Optimize it by copying only the RELY header
+
+    // Be sure encoder can produce
+    assert(can_produce());
+
+    // Check new payload size and make sure it fits in packet buffer
+    auto new_payload_size = produce_bytes();
+    int difference = new_payload_size - length;
+
+    assert(difference > 0);
+    assert(content_object.ensureCapacity(difference));
+
+    // Update length
+    DLOG_IF(INFO, VLOG_IS_ON(4)) << "The packet length will be incremented by "
+                                 << difference + sizeof(fec_header);
+    content_object.append(difference + sizeof(fec_header));
+    content_object.updateLength();
+
+    // Make sure we got a source packet, otherwise we would put a repair symbol
+    // in a source packet
+    assert(rely::packet_is_systematic(produce_data()));
+
+    // Copy rely packet replacing old source packet.
+    std::memcpy(data, produce_data(), new_payload_size);
+
+    // Advance the encoder to next symbol.
+    produce_next();
+  }
+
+#if 0
+  if (i == k_) {
+    // Ensure repair are generated after k source packets
+    flush_repair();
+  }
+#endif
+
+  // Here we should produce all the repair packets
+  while (can_produce()) {
+    // The current index MUST be k_, because we enforce n - k repair to be
+    // produced after k sources
+    assert(current_index_ == k_);
+
+    buffer packet;
+    if (!buffer_callback_) {
+      // If no callback is installed, let's allocate a buffer from global pool
+      packet = core::PacketManager<>::getInstance().getMemBuf();
+      packet->append(produce_bytes());
+    } else {
+      // Otherwise let's ask a buffer to the caller.
+      packet = buffer_callback_(produce_bytes());
+    }
+
+    DLOG_IF(INFO, VLOG_IS_ON(4))
+        << "Producing symbol of size " << produce_bytes();
+
+    // Copy symbol to packet buffer
+    std::memcpy(packet->writableData(), produce_data(), produce_bytes());
+
+    // Push symbol in repair_packets
+    packets_.emplace_back(0, std::move(packet));
+
+    // Advance the encoder
+    produce_next();
+  }
+
+  // Print number of unprotected symbols
+  DLOG_IF(INFO, VLOG_IS_ON(4))
+      << "Number of unprotected symbols: " << unprotected_symbols();
+
+  // If we have generated repair symbols, let's notify caller via the installed
+  // callback
+  if (packets_.size()) {
+    assert(packets_.size() == n_ - k_);
+    fec_callback_(packets_);
+    packets_.clear();
+    current_index_ = 0;
+  }
+}
+
+RelyDecoder::RelyDecoder(uint32_t k, uint32_t n, uint32_t seq_offset)
+    : RelyBase(k, n, seq_offset) {
+  configure(kmtu, ktimeout, kmax_stream_size);
+}
+
+void RelyDecoder::onDataPacket(core::ContentObject &content_object,
+                               uint32_t offset) {
+  // Adjust pointers to point to packet payload
+  auto data = content_object.writableData() + offset;
+  auto size = content_object.length() - offset;
+
+  // Pass payload to decoder
+  consume(data, size, getCurrentTime());
+
+  // Drain decoder if possible
+  while (can_produce()) {
+    // Get size of decoded packet
+    auto size = produce_bytes();
+
+    // Get buffer to copy packet in
+    auto packet = core::PacketManager<>::getInstance().getMemBuf();
+
+    // Copy buffer
+    packet->append(size);
+    std::memcpy(packet->writableData(), produce_data(), size);
+
+    // Read seq number
+    fec_header *h = reinterpret_cast<fec_header *>(packet->writableData());
+    uint32_t index = h->getSeqNumberBase();
+
+    DLOG_IF(INFO, VLOG_IS_ON(4))
+        << "The index written in the packet is " << index;
+
+    // Remove FEC header
+    packet->trimStart(sizeof(fec_header));
+
+    // Save packet in buffer
+    packets_.emplace_back(index, std::move(packet));
+
+    // Advance to next packet
+    produce_next();
+  }
+
+  // If we produced packets, lets notify the caller via the callback
+  if (packets_.size() > 0) {
+    fec_callback_(packets_);
+    packets_.clear();
+  }
+}
+
+}  // namespace fec
+}  // namespace protocol
+}  // namespace transport
\ No newline at end of file
diff --git a/libtransport/src/protocols/fec/rely.h b/libtransport/src/protocols/fec/rely.h
new file mode 100644
index 000000000..bfbdb30bc
--- /dev/null
+++ b/libtransport/src/protocols/fec/rely.h
@@ -0,0 +1,191 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <hicn/transport/utils/chrono_typedefs.h>
+#include <hicn/transport/utils/membuf.h>
+#include <protocols/fec/fec_info.h>
+#include <protocols/fec_base.h>
+
+#include <rely/decoder.hpp>
+#include <rely/encoder.hpp>
+
+#define RELY_DEBUG 0
+
+namespace transport {
+namespace protocol {
+namespace fec {
+
+/**
+ * @brief Table of used codes.
+ */
+#define foreach_rely_fec_type \
+  _(Rely, 1, 3)               \
+  _(Rely, 2, 3)               \
+  _(Rely, 4, 5)               \
+  _(Rely, 4, 6)               \
+  _(Rely, 4, 7)               \
+  _(Rely, 6, 10)              \
+  _(Rely, 8, 10)              \
+  _(Rely, 8, 11)              \
+  _(Rely, 8, 12)              \
+  _(Rely, 8, 14)              \
+  _(Rely, 8, 16)              \
+  _(Rely, 8, 32)              \
+  _(Rely, 10, 30)             \
+  _(Rely, 10, 40)             \
+  _(Rely, 10, 90)             \
+  _(Rely, 16, 21)             \
+  _(Rely, 16, 23)             \
+  _(Rely, 16, 24)             \
+  _(Rely, 16, 27)             \
+  _(Rely, 17, 21)             \
+  _(Rely, 17, 34)             \
+  _(Rely, 32, 41)             \
+  _(Rely, 32, 46)             \
+  _(Rely, 32, 54)             \
+  _(Rely, 34, 42)             \
+  _(Rely, 35, 70)             \
+  _(Rely, 52, 62)
+
+/**
+ * @brief Base class to store common fields.
+ */
+class RelyBase : public virtual FECBase {
+ protected:
+  static const constexpr size_t kmax_stream_size = 125U;
+  static const constexpr size_t kmtu = 1500U;
+  static const constexpr size_t ktimeout = 100U;
+  /**
+   * @brief FEC Header, added to each packet to get sequence number upon
+   * decoding operations. It may be removed once we know the meaning of the
+   * fields in the rely header.
+   */
+  struct fec_header {
+    uint32_t seq_number;
+
+    void setSeqNumberBase(uint32_t suffix) { seq_number = htonl(suffix); }
+    uint32_t getSeqNumberBase() { return ntohl(seq_number); }
+  };
+
+  /**
+   * @brief Construct a new Rely Base object.
+   *
+   * @param k The number of source symbol needed to generate n - k repair
+   * symbols
+   * @param n The sum of source packets and repair packets in a `block`
+   * @param seq_offset offset to use if production suffixes starts from an index
+   * != 0
+   */
+  RelyBase(uint32_t k, uint32_t n, uint32_t seq_offset = 0)
+      : k_(k),
+        n_(n),
+        seq_offset_(seq_offset % n_),
+        current_index_(seq_offset)
+#if RELY_DEBUG
+        ,
+        time_(0)
+#endif
+  {
+  }
+
+  /**
+   * @brief Get the current time in milliseconds
+   *
+   * @return int64_t Current time in milliseconds
+   */
+  int64_t getCurrentTime() {
+    // Get the current time
+#if RELY_DEBUG
+    return time_++;
+#else
+    auto _time = utils::SteadyClock::now().time_since_epoch();
+    auto time = std::chrono::duration_cast<utils::Milliseconds>(_time).count();
+    return time;
+#endif
+  }
+
+ protected:
+  uint32_t k_;
+  uint32_t n_;
+  std::uint32_t seq_offset_;
+  /**
+   * @brief Vector of packets to be passed to caller callbacks. For encoder it
+   * will contain the repair packets, for decoder the recovered sources.
+   */
+  std::vector<std::pair<uint32_t, buffer>> packets_;
+
+  /**
+   * @brief Current index to be used for local packet count.
+   *
+   */
+  uint32_t current_index_;
+#if RELY_DEBUG
+  uint32_t time_;
+#endif
+};
+
+/**
+ * @brief The Rely Encoder implementation.
+ *
+ */
+class RelyEncoder : private RelyBase,
+                    private rely::encoder,
+                    public ProducerFEC {
+ public:
+  RelyEncoder(uint32_t k, uint32_t n, uint32_t seq_offset = 0);
+  /**
+   * Producers will call this function when they produce a data packet.
+   */
+  void onPacketProduced(core::ContentObject &content_object,
+                        uint32_t offset) override;
+
+  /**
+   * @brief Get the fec header size, if added to source packets
+   */
+  std::size_t getFecHeaderSize() override {
+    return header_bytes() + sizeof(fec_header) + 4;
+  }
+
+  void reset() override {}
+};
+
+class RelyDecoder : private RelyBase,
+                    private rely::decoder,
+                    public ConsumerFEC {
+ public:
+  RelyDecoder(uint32_t k, uint32_t n, uint32_t seq_offset = 0);
+
+  /**
+   * Consumers will call this function when they receive a data packet
+   */
+  void onDataPacket(core::ContentObject &content_object,
+                    uint32_t offset) override;
+
+  /**
+   * @brief Get the fec header size, if added to source packets
+   */
+  std::size_t getFecHeaderSize() override {
+    return header_bytes() + sizeof(fec_header);
+  }
+
+  void reset() override {}
+};
+
+}  // namespace fec
+
+}  // namespace protocol
+}  // namespace transport
\ No newline at end of file
diff --git a/libtransport/src/protocols/fec/rs.cc b/libtransport/src/protocols/fec/rs.cc
new file mode 100644
index 000000000..2c23d515d
--- /dev/null
+++ b/libtransport/src/protocols/fec/rs.cc
@@ -0,0 +1,418 @@
+
+/*
+ * 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 <glog/logging.h>
+#include <hicn/transport/core/global_object_pool.h>
+#include <protocols/fec/fec.h>
+#include <protocols/fec/rs.h>
+
+#include <cassert>
+
+namespace transport {
+namespace protocol {
+namespace fec {
+
+BlockCode::BlockCode(uint32_t k, uint32_t n, uint32_t seq_offset,
+                     struct fec_parms *code, rs &params)
+    : Packets(),
+      k_(k),
+      n_(n),
+      seq_offset_(seq_offset),
+      code_(code),
+      max_buffer_size_(0),
+      current_block_size_(0),
+      to_decode_(false),
+      params_(params) {
+  sorted_index_.reserve(n);
+  UNUSED(seq_offset_);
+}
+
+bool BlockCode::addRepairSymbol(const fec::buffer &packet, uint32_t i,
+                                uint32_t offset) {
+  // Get index
+  to_decode_ = true;
+  DLOG_IF(INFO, VLOG_IS_ON(4)) << "Adding symbol of size " << packet->length();
+  return addSymbol(packet, i, offset,
+                   packet->length() - sizeof(fec_header) - offset);
+}
+
+bool BlockCode::addSourceSymbol(const fec::buffer &packet, uint32_t i,
+                                uint32_t offset) {
+  DLOG_IF(INFO, VLOG_IS_ON(4)) << "Adding source symbol of size "
+                               << packet->length() << ", offset " << offset;
+  return addSymbol(packet, i, offset, packet->length() - offset);
+}
+
+bool BlockCode::addSymbol(const fec::buffer &packet, uint32_t i,
+                          uint32_t offset, std::size_t size) {
+  if (size > max_buffer_size_) {
+    max_buffer_size_ = size;
+  }
+
+  operator[](current_block_size_++) = std::make_tuple(i, packet, offset);
+
+  if (current_block_size_ >= k_) {
+    if (to_decode_) {
+      decode();
+    } else {
+      encode();
+    }
+
+    clear();
+    return false;
+  }
+
+  return true;
+}
+
+void BlockCode::encode() {
+  gf *data[n_];
+  uint32_t base = std::get<0>(operator[](0));
+
+  // Set packet length in first 2 bytes
+  for (uint32_t i = 0; i < k_; i++) {
+    auto &packet = std::get<1>(operator[](i));
+    auto offset = std::get<2>(operator[](i));
+
+    auto ret =
+        packet->ensureCapacityAndFillUnused(max_buffer_size_ + offset, 0);
+    if (TRANSPORT_EXPECT_FALSE(ret == false)) {
+      throw errors::RuntimeException(
+          "Provided packet is not suitable to be used as FEC source packet. "
+          "Aborting.");
+    }
+
+    // Buffers should hold 2 *after* the padding, in order to be
+    // able to set the length for the encoding operation.
+    // packet->trimStart(offset);
+    uint16_t *length = reinterpret_cast<uint16_t *>(packet->writableData() +
+                                                    max_buffer_size_ + offset);
+    auto buffer_length = packet->length() - offset;
+    *length = htons(buffer_length);
+
+    DLOG_IF(INFO, VLOG_IS_ON(4)) << "Current buffer size: " << packet->length();
+
+    data[i] = packet->writableData() + offset;
+  }
+
+  // Finish to fill source block with the buffers to hold the repair symbols
+  auto length = max_buffer_size_ + sizeof(fec_header) + LEN_SIZE_BYTES;
+  for (uint32_t i = k_; i < n_; i++) {
+    buffer packet;
+    if (!params_.buffer_callback_) {
+      // If no callback is installed, let's allocate a buffer from global pool
+      packet = core::PacketManager<>::getInstance().getMemBuf();
+      packet->append(length);
+    } else {
+      // Otherwise let's ask a buffer to the caller.
+      packet = params_.buffer_callback_(length);
+    }
+
+    fec_header *fh = reinterpret_cast<fec_header *>(packet->writableData());
+
+    fh->setSeqNumberBase(base);
+    fh->setNFecSymbols(n_ - k_);
+    fh->setEncodedSymbolId(i);
+    fh->setSourceBlockLen(n_);
+
+    packet->trimStart(sizeof(fec_header));
+
+    DLOG_IF(INFO, VLOG_IS_ON(4)) << "Current symbol size: " << packet->length();
+
+    data[i] = packet->writableData();
+    operator[](i) = std::make_tuple(i, std::move(packet), uint32_t(0));
+  }
+
+  // Generate repair symbols and put them in corresponding buffers
+  DLOG_IF(INFO, VLOG_IS_ON(4))
+      << "Calling encode with max_buffer_size_ = " << max_buffer_size_;
+  for (uint32_t i = k_; i < n_; i++) {
+    fec_encode(code_, data, data[i], i, max_buffer_size_ + LEN_SIZE_BYTES);
+  }
+
+  // Re-include header in repair packets
+  for (uint32_t i = k_; i < n_; i++) {
+    auto &packet = std::get<1>(operator[](i));
+    packet->prepend(sizeof(fec_header));
+    DLOG_IF(INFO, VLOG_IS_ON(4))
+        << "Produced repair symbol of size = " << packet->length();
+  }
+}
+
+void BlockCode::decode() {
+  gf *data[k_];
+  uint32_t index[k_];
+
+  for (uint32_t i = 0; i < k_; i++) {
+    auto &packet = std::get<1>(operator[](i));
+    index[i] = std::get<0>(operator[](i));
+    auto offset = std::get<2>(operator[](i));
+    sorted_index_[i] = index[i];
+
+    if (index[i] < k_) {
+      DLOG_IF(INFO, VLOG_IS_ON(4))
+          << "DECODE SOURCE - index " << index[i]
+          << " - Current buffer size: " << packet->length();
+      // This is a source packet. We need to fill
+      // additional space to 0 and append the length
+
+      // Buffers should hold 2 bytes at the end, in order to be
+      // able to set the length for the encoding operation
+      packet->trimStart(offset);
+      packet->ensureCapacityAndFillUnused(max_buffer_size_, 0);
+      uint16_t *length = reinterpret_cast<uint16_t *>(
+          packet->writableData() + max_buffer_size_ - LEN_SIZE_BYTES);
+
+      *length = htons(packet->length());
+    } else {
+      DLOG_IF(INFO, VLOG_IS_ON(4))
+          << "DECODE SYMBOL - index " << index[i]
+          << " - Current buffer size: " << packet->length();
+      packet->trimStart(sizeof(fec_header) + offset);
+    }
+
+    data[i] = packet->writableData();
+  }
+
+  // We decode the source block
+  DLOG_IF(INFO, VLOG_IS_ON(4))
+      << "Calling decode with max_buffer_size_ = " << max_buffer_size_;
+  fec_decode(code_, data, reinterpret_cast<int *>(index), max_buffer_size_);
+
+  // Find the index in the block for recovered packets
+  for (uint32_t i = 0; i < k_; i++) {
+    if (index[i] != i) {
+      for (uint32_t j = 0; j < k_; j++)
+        if (sorted_index_[j] == uint32_t(index[i])) {
+          sorted_index_[j] = i;
+        }
+    }
+  }
+
+  // Reorder block by index with in-place sorting
+  for (uint32_t i = 0; i < k_; i++) {
+    for (uint32_t j = sorted_index_[i]; j != i; j = sorted_index_[i]) {
+      std::swap(sorted_index_[j], sorted_index_[i]);
+      std::swap(operator[](j), operator[](i));
+    }
+  }
+
+  // Adjust length according to the one written in the source packet
+  for (uint32_t i = 0; i < k_; i++) {
+    auto &packet = std::get<1>(operator[](i));
+    uint16_t *length = reinterpret_cast<uint16_t *>(
+        packet->writableData() + max_buffer_size_ - LEN_SIZE_BYTES);
+    packet->setLength(ntohs(*length));
+  }
+}
+
+void BlockCode::clear() {
+  current_block_size_ = 0;
+  max_buffer_size_ = 0;
+  sorted_index_.clear();
+  to_decode_ = false;
+}
+
+void rs::MatrixDeleter::operator()(struct fec_parms *params) {
+  fec_free(params);
+}
+
+rs::Codes rs::createCodes() {
+  Codes ret;
+
+#define _(name, k, n) \
+  ret.emplace(std::make_pair(k, n), Matrix(fec_new(k, n), MatrixDeleter()));
+  foreach_rs_fec_type
+#undef _
+
+      return ret;
+}
+
+rs::Codes rs::codes_ = createCodes();
+
+rs::rs(uint32_t k, uint32_t n, uint32_t seq_offset)
+    : k_(k), n_(n), seq_offset_(seq_offset % n) {}
+
+RSEncoder::RSEncoder(uint32_t k, uint32_t n, uint32_t seq_offset)
+    : rs(k, n, seq_offset),
+      current_code_(codes_[std::make_pair(k, n)].get()),
+      source_block_(k_, n_, seq_offset_, current_code_, *this) {}
+
+void RSEncoder::consume(const fec::buffer &packet, uint32_t index,
+                        uint32_t offset) {
+  if (!source_block_.addSourceSymbol(packet, index, offset)) {
+    std::vector<std::pair<uint32_t, buffer>> repair_packets;
+    for (uint32_t i = k_; i < n_; i++) {
+      repair_packets.emplace_back(std::move(std::get<0>(source_block_[i])),
+                                  std::move(std::get<1>(source_block_[i])));
+    }
+
+    fec_callback_(repair_packets);
+  }
+}
+
+void RSEncoder::onPacketProduced(core::ContentObject &content_object,
+                                 uint32_t offset) {
+  consume(content_object.shared_from_this(),
+          content_object.getName().getSuffix(), offset);
+}
+
+RSDecoder::RSDecoder(uint32_t k, uint32_t n, uint32_t seq_offset)
+    : rs(k, n, seq_offset) {}
+
+void RSDecoder::recoverPackets(SourceBlocks::iterator &src_block_it) {
+  DLOG_IF(INFO, VLOG_IS_ON(4)) << "recoverPackets for " << k_;
+  auto &src_block = src_block_it->second;
+  std::vector<std::pair<uint32_t, buffer>> source_packets(k_);
+  for (uint32_t i = 0; i < src_block.getK(); i++) {
+    source_packets[i] = std::make_pair(src_block_it->first + i,
+                                       std::move(std::get<1>(src_block[i])));
+  }
+
+  setProcessed(src_block_it->first);
+
+  fec_callback_(source_packets);
+  processed_source_blocks_.emplace(src_block_it->first);
+
+  auto it = parked_packets_.find(src_block_it->first);
+  if (it != parked_packets_.end()) {
+    parked_packets_.erase(it);
+  }
+
+  src_blocks_.erase(src_block_it);
+}
+
+void RSDecoder::consumeSource(const fec::buffer &packet, uint32_t index,
+                              uint32_t offset) {
+  // Normalize index
+  assert(index >= seq_offset_);
+  auto i = (index - seq_offset_) % n_;
+
+  // Get base
+  uint32_t base = index - i;
+
+  if (processed(base)) {
+    return;
+  }
+
+  DLOG_IF(INFO, VLOG_IS_ON(4))
+      << "Decoder consume called for source symbol. BASE = " << base
+      << ", index = " << index << " and i = " << i;
+
+  // check if a source block already exist for this symbol. If it does not
+  // exist, we lazily park this packet until we receive a repair symbol for the
+  // same block. This is done for 2 reason:
+  // 1) If we receive all the source packets of a block, we do not need to
+  //    recover anything.
+  // 2) Sender may change n and k at any moment, so we construct the source
+  //    block based on the (n, k) values written in the fec header. This is
+  //    actually not used right now, since we use fixed value of n and k passed
+  //    at construction time, but it paves the ground for a more dynamic
+  //    protocol that may come in the future.
+  auto it = src_blocks_.find(base);
+  if (it != src_blocks_.end()) {
+    auto ret = it->second.addSourceSymbol(packet, i, offset);
+    if (!ret) {
+      recoverPackets(it);
+    }
+  } else {
+    DLOG_IF(INFO, VLOG_IS_ON(4)) << "Adding to parked source packets";
+    auto ret = parked_packets_.emplace(
+        base, std::vector<std::pair<buffer, uint32_t>>());
+    ret.first->second.emplace_back(packet, i);
+
+    if (ret.first->second.size() >= k_) {
+      setProcessed(ret.first->first);
+      parked_packets_.erase(ret.first);
+    }
+  }
+}
+
+void RSDecoder::consumeRepair(const fec::buffer &packet, uint32_t offset) {
+  // Repair symbol! Get index and base source block.
+  fec_header *h =
+      reinterpret_cast<fec_header *>(packet->writableData() + offset);
+  auto i = h->getEncodedSymbolId();
+  auto base = h->getSeqNumberBase();
+  auto n = h->getSourceBlockLen();
+  auto k = n - h->getNFecSymbols();
+
+  if (processed(base)) {
+    return;
+  }
+
+  DLOG_IF(INFO, VLOG_IS_ON(4))
+      << "Decoder consume called for repair symbol. BASE = " << base
+      << ", index = " << base + i << " and i = " << i << ". K=" << k
+      << ", N=" << n;
+
+  // check if a source block already exist for this symbol
+  auto it = src_blocks_.find(base);
+  if (it == src_blocks_.end()) {
+    // Create new source block
+    auto code_it = codes_.find(std::make_pair(k, n));
+    if (code_it == codes_.end()) {
+      LOG(ERROR) << "Code for k = " << k << " and n = " << n
+                 << " does not exist.";
+      return;
+    }
+
+    auto emplace_result = src_blocks_.emplace(
+        base, BlockCode(k, n, seq_offset_, code_it->second.get(), *this));
+    it = emplace_result.first;
+
+    // Check in the parked packets and insert any packet that is part of this
+    // source block
+
+    auto it2 = parked_packets_.find(base);
+    if (it2 != parked_packets_.end()) {
+      for (auto &packet_index : it2->second) {
+        auto ret = it->second.addSourceSymbol(packet_index.first,
+                                              packet_index.second, offset);
+        if (!ret) {
+          recoverPackets(it);
+          // Finish to delete packets in same source block that were
+          // eventually not used
+          return;
+        }
+      }
+    }
+  }
+
+  auto ret = it->second.addRepairSymbol(packet, i, offset);
+  if (!ret) {
+    recoverPackets(it);
+  }
+}
+
+void RSDecoder::onDataPacket(core::ContentObject &content_object,
+                             uint32_t offset) {
+  DLOG_IF(INFO, VLOG_IS_ON(4))
+      << "Calling fec for data packet " << content_object.getName()
+      << ". Offset: " << offset;
+
+  auto suffix = content_object.getName().getSuffix();
+
+  if (isSymbol(suffix)) {
+    consumeRepair(content_object.shared_from_this(), offset);
+  } else {
+    consumeSource(content_object.shared_from_this(), suffix, offset);
+  }
+}
+
+}  // namespace fec
+}  // namespace protocol
+}  // namespace transport
diff --git a/libtransport/src/protocols/fec/rs.h b/libtransport/src/protocols/fec/rs.h
new file mode 100644
index 000000000..e159ad9f7
--- /dev/null
+++ b/libtransport/src/protocols/fec/rs.h
@@ -0,0 +1,409 @@
+
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <arpa/inet.h>
+#include <hicn/transport/portability/c_portability.h>
+#include <hicn/transport/utils/membuf.h>
+#include <protocols/fec/fec_info.h>
+#include <protocols/fec_base.h>
+
+#include <array>
+#include <cstdint>
+#include <map>
+#include <unordered_set>
+#include <vector>
+
+namespace transport {
+namespace protocol {
+
+namespace fec {
+
+#define foreach_rs_fec_type \
+  _(RS, 1, 3)               \
+  _(RS, 4, 5)               \
+  _(RS, 4, 6)               \
+  _(RS, 4, 7)               \
+  _(RS, 6, 10)              \
+  _(RS, 8, 10)              \
+  _(RS, 8, 11)              \
+  _(RS, 8, 12)              \
+  _(RS, 8, 14)              \
+  _(RS, 8, 16)              \
+  _(RS, 8, 32)              \
+  _(RS, 10, 30)             \
+  _(RS, 10, 40)             \
+  _(RS, 10, 60)             \
+  _(RS, 10, 90)             \
+  _(RS, 16, 18)             \
+  _(RS, 16, 21)             \
+  _(RS, 16, 23)             \
+  _(RS, 16, 24)             \
+  _(RS, 16, 27)             \
+  _(RS, 17, 21)             \
+  _(RS, 17, 34)             \
+  _(RS, 32, 36)             \
+  _(RS, 32, 41)             \
+  _(RS, 32, 46)             \
+  _(RS, 32, 54)             \
+  _(RS, 34, 42)             \
+  _(RS, 35, 70)             \
+  _(RS, 52, 62)
+
+static const constexpr uint16_t MAX_SOURCE_BLOCK_SIZE = 128;
+
+/**
+ * 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::tuple</* index */ uint32_t, /* buffer */ buffer,
+                                      uint32_t /* offset */>,
+                           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; }
+};
+
+class rs;
+
+/**
+ * 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, uint32_t seq_offset, struct fec_parms *code,
+            rs &params);
+
+  /**
+   * Add a repair symbol to the dource block.
+   */
+  bool addRepairSymbol(const fec::buffer &packet, uint32_t i,
+                       uint32_t offset = 0);
+
+  /**
+   * Add a source symbol to the source block.
+   */
+  bool addSourceSymbol(const fec::buffer &packet, uint32_t i,
+                       uint32_t offset = 0);
+
+  /**
+   * 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, uint32_t offset,
+                 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_;
+  uint32_t seq_offset_;
+  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_;
+  rs &params_;
+};
+
+/**
+ * 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 : public virtual FECBase {
+  friend class BlockCode;
+
+  /**
+   * 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 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, uint32_t seq_offset = 0);
+  ~rs() = default;
+
+  virtual void clear() { processed_source_blocks_.clear(); }
+
+  bool isSymbol(uint32_t index) { return ((index - seq_offset_) % n_) >= k_; }
+
+ 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();
+  }
+
+  void setProcessed(SNBase seq_base) {
+    processed_source_blocks_.emplace(seq_base);
+  }
+
+  std::uint32_t k_;
+  std::uint32_t n_;
+  std::uint32_t seq_offset_;
+
+  /**
+   * 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 RSEncoder : public rs, public ProducerFEC {
+ public:
+  RSEncoder(uint32_t k, uint32_t n, uint32_t seq_offset = 0);
+  /**
+   * Always consume source symbols.
+   */
+  void consume(const fec::buffer &packet, uint32_t index, uint32_t offset = 0);
+
+  void onPacketProduced(core::ContentObject &content_object,
+                        uint32_t offset) override;
+
+  /**
+   * @brief Get the fec header size, if added to source packets
+   */
+  std::size_t getFecHeaderSize() override { return 0; }
+
+  void clear() override {
+    rs::clear();
+    source_block_.clear();
+  }
+
+  void reset() override { 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 RSDecoder : public rs, public ConsumerFEC {
+ public:
+  RSDecoder(uint32_t k, uint32_t n, uint32_t seq_offset = 0);
+
+  /**
+   * Consume source symbol
+   */
+  void consumeSource(const fec::buffer &packet, uint32_t i,
+                     uint32_t offset = 0);
+
+  /**
+   * Consume repair symbol
+   */
+  void consumeRepair(const fec::buffer &packet, uint32_t offset = 0);
+
+  /**
+   * Consumers will call this function when they receive a data packet
+   */
+  void onDataPacket(core::ContentObject &content_object,
+                    uint32_t offset) override;
+
+  /**
+   * @brief Get the fec header size, if added to source packets
+   */
+  std::size_t getFecHeaderSize() override { return 0; }
+
+  /**
+   * Clear decoder to reuse
+   */
+  void clear() override {
+    rs::clear();
+    src_blocks_.clear();
+    parked_packets_.clear();
+  }
+
+  void reset() override { 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 protocol
+
+}  // namespace transport