Implement the Pearson hash method.

1 files changed, 179 insertions, 0 deletions

diff --git a/plugins/pychrysalide/common/pearson.c b/plugins/pychrysalide/common/pearson.c
new file mode 100644
index 0000000..99c2d27
--- /dev/null
+++ b/plugins/pychrysalide/common/pearson.c
@@ -0,0 +1,179 @@
+
+/* Chrysalide - Outil d'analyse de fichiers binaires
+ * pearson.c - équivalent Python du fichier "common/pearson.c"
+ *
+ * Copyright (C) 2018-2019 Cyrille Bagard
+ *
+ *  This file is part of Chrysalide.
+ *
+ *  Chrysalide is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Chrysalide is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+
+#include "pearson.h"
+
+
+#include <pygobject.h>
+
+
+#include <i18n.h>
+#include <common/pearson.h>
+
+
+#include "../access.h"
+#include "../helpers.h"
+
+
+
+/* Fournit les permutations par défaut par Pearson. */
+static PyObject *py_pearson_permutations(PyObject *, PyObject *);
+
+/* Détermine l'empreinte Pearson d'une chaîne de caractères. */
+static PyObject *py_pearson(PyObject *, PyObject *);
+
+
+
+/******************************************************************************
+*                                                                             *
+*  Paramètres  : self = NULL car méthode statique.                            *
+*                args = adresse non utilisée ici, en l'absence d'argument.    *
+*                                                                             *
+*  Description : Fournit les permutations par défaut par Pearson.             *
+*                                                                             *
+*  Retour      : Table de valeurs utilisées par défaut.                       *
+*                                                                             *
+*  Remarques   : -                                                            *
+*                                                                             *
+******************************************************************************/
+
+static PyObject *py_pearson_permutations(PyObject *self, PyObject *args)
+{
+    PyObject *result;                       /* Instance à retourner        */
+    const char *table;                      /* Eventuelle table à utiliser */
+
+#define PEARSON_PERMUTATIONS_METHOD PYTHON_METHOD_DEF   \
+(                                                       \
+    pearson_permutations, "",                           \
+    METH_NOARGS, py,                                    \
+    "Provide the default pseudorandom permutations"     \
+    " for the Pearson hash computation.\n"              \
+    "\n"                                                \
+    "The result is 256-byte value."                     \
+)
+
+    table = get_pearson_permutations();
+
+    result = PyBytes_FromStringAndSize(table, 256);
+
+    return result;
+
+}
+
+
+/******************************************************************************
+*                                                                             *
+*  Paramètres  : self = NULL car méthode statique.                            *
+*                args = arguments fournis lors de l'appel à la fonction.      *
+*                                                                             *
+*  Description : Détermine l'empreinte Pearson d'une chaîne de caractères.    *
+*                                                                             *
+*  Retour      : Numéro de révision.                                          *
+*                                                                             *
+*  Remarques   : -                                                            *
+*                                                                             *
+******************************************************************************/
+
+static PyObject *py_pearson(PyObject *self, PyObject *args)
+{
+    PyObject *result;                       /* Instance à retourner        */
+    const char *str;                        /* Chaîne à traiter.           */
+    PyObject *bytes;                        /* Tableau d'octets            */
+    int ret;                                /* Bilan de lecture des args.  */
+    const char *table;                      /* Eventuelle table à utiliser */
+    uint8_t value;                          /* Empreinte calculée          */
+
+#define PEARSON_METHOD PYTHON_METHOD_DEF                        \
+(                                                               \
+    pearson, "str, /, table",                                   \
+    METH_VARARGS, py,                                           \
+    "Compute the Pearson hash of a given string.\n"             \
+    "\n"                                                        \
+    "The default pseudorandom permutations are used if"         \
+    " no *table* of 256 bytes is provided.\n"                   \
+    "\n"                                                        \
+    "A table of permutations can be created with this call:\n"  \
+    "  bytes(sample(list(range(0, 256)), k=256))\n"             \
+    "\n"                                                        \
+    "The result is 8-bit integer value."                        \
+)
+
+    bytes = NULL;
+
+    ret = PyArg_ParseTuple(args, "s|O!", &str, &PyBytes_Type, &bytes);
+    if (!ret) return NULL;
+
+    if (bytes != NULL)
+    {
+        if (PyBytes_Size(bytes) != 256)
+        {
+            PyErr_SetString(PyExc_ValueError, _("256 bytes are required for the custom table."));
+            return NULL;
+        }
+
+        table = PyBytes_AsString(bytes);
+
+        value = pearson_hash(str, table);
+
+    }
+    else
+        value = pearson_hash(str, NULL);
+
+    result = Py_BuildValue("B", (unsigned char)value);
+
+    return result;
+
+}
+
+
+/******************************************************************************
+*                                                                             *
+*  Paramètres  : -                                                            *
+*                                                                             *
+*  Description : Définit une extension du module 'common' à compléter.        *
+*                                                                             *
+*  Retour      : Bilan de l'opération.                                        *
+*                                                                             *
+*  Remarques   : -                                                            *
+*                                                                             *
+******************************************************************************/
+
+bool populate_common_module_with_pearson(void)
+{
+    bool result;                            /* Bilan à retourner           */
+    PyObject *module;                       /* Module à recompléter        */
+
+    static PyMethodDef py_pearson_methods[] = {
+        PEARSON_PERMUTATIONS_METHOD,
+        PEARSON_METHOD,
+        { NULL }
+    };
+
+    module = get_access_to_python_module("pychrysalide.common");
+
+    result = register_python_module_methods(module, py_pearson_methods);
+
+    return result;
+
+}