CCSDS_study project

netzob-030/lib/libRelation/algorithms/rel_equality.c

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+// -*- coding: utf-8 -*-
+
+//+---------------------------------------------------------------------------+
+//|          01001110 01100101 01110100 01111010 01101111 01100010            |
+//|                                                                           |
+//|               Netzob : Inferring communication protocols                  |
+//+---------------------------------------------------------------------------+
+//| Copyright (C) 2011-2017 Georges Bossert and Frédéric Guihéry              |
+//| This program 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.                                       |
+//|                                                                           |
+//| This program 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, see <http://www.gnu.org/licenses/>.      |
+//+---------------------------------------------------------------------------+
+//| @url      : http://www.netzob.org                                         |
+//| @contact  : contact@netzob.org                                            |
+//| @sponsors : Amossys, http://www.amossys.fr                                |
+//|             Supélec, http://www.rennes.supelec.fr/ren/rd/cidre/           |
+//+---------------------------------------------------------------------------+
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include "relation.h"
+
+static unsigned int MIN_SIZE = 2;
+
+/*
+ * wrapper of string comparison used to detect a relation with the
+ * specified parameters.
+ */
+static int
+get_match(const char* cell_ref, const char* cell_rel,
+	  size_t start, size_t len)
+{
+    int ret;
+#if defined(__DEBUG__) && false
+    char* new_rel;
+    if ((new_rel = malloc((len + 1) * sizeof(*new_rel)))) {
+        new_rel[len] = '\0';
+        DLOG("%s == %s ?", cell_ref, strncpy(new_rel, &cell_rel[start], len));
+        free(new_rel);
+    }
+#endif
+    ret = strncmp(cell_ref, &cell_rel[start], len);
+#if defined(__DEBUG__) && false
+    DLOG(" %d\n", ret);
+#endif
+    return ret;
+}
+
+/*
+ * Append a node to the set of matches.
+ */
+static struct relation_matches*
+append_match(struct relation_matches** matches,
+	     const struct relation_match* match)
+{
+    struct relation_matches* new = NULL;
+
+    if (!(new = malloc(sizeof(*new))))
+        return NULL;
+    new->next = *matches;
+    memcpy(&new->match, match, sizeof(new->match));
+    *matches = new;
+    return new;
+}
+
+/*
+ * Returns the first non-matching message index.
+ */
+static int
+verify_match(const char*** messages, size_t msgs_len, size_t cells_len,
+	     const struct relation_match* match)
+{
+    int i;
+    int ret = 0;
+    const char** cells;
+    const char* ref;
+    const char* rel;
+
+    DLOG("Verifying M%04d", 0);
+    for (i = 0; i < msgs_len; i++) {
+        if (i == match->message_idx)
+            continue;
+        cells = messages[i];
+        ref = cells[match->cell_ref_idx];
+        rel = cells[match->cell_rel_idx];
+        DLOG2("\b\b\b\b%04d", i);
+        if (get_match(ref, rel, match->cell_rel_off, match->cell_rel_size)) {
+            ret = i;
+            break;
+        }
+    }
+    DLOG2("\n");
+    return ret;
+}
+
+/*
+ * Main function used to build a set of matches.
+ */
+static struct relation_matches*
+relation_equality_find(const char*** messages, int row, int idx,
+		       size_t vlen, size_t hlen)
+{
+    int i, ret;
+    size_t off;
+    int found = 0;
+    int match_res;
+    const char** cells;
+    const char* ref;
+    size_t ref_len;
+    const char* rel;
+    size_t rel_len;
+    struct relation_matches* matches = NULL;
+    struct relation_match match;
+
+    cells = messages[row];
+    ref = cells[idx];
+    ref_len = strlen(ref);
+    for (i = 0; i < hlen; i++) {
+        rel = cells[i];
+        rel_len = strlen(rel);
+        if (i != idx && rel && ref_len <= rel_len && ref_len >= MIN_SIZE) {
+            for (off = 0; off <= rel_len - ref_len; off++) {
+                if (!(match_res = get_match(ref, rel, off, ref_len))) {
+                    match.message_idx = row;
+                    match.cell_ref_idx = idx;
+                    match.cell_rel_idx = i;
+                    match.cell_rel_off = off;
+                    match.cell_rel_size = ref_len;
+                    DLOG("possible match found: M%d F%d[:], F%d[%ld:%ld] (%s)\n",
+			 row, idx, i, off, off+ref_len, ref);
+                    if ((ret = verify_match(messages, vlen, hlen,
+					    (const struct relation_match*)&match)) != 0) {
+                        DLOG("verification failed at M%d\n", ret);
+                        continue;
+                    }
+                    DLOG("MATCH FOUND\n");
+                    DLOG(">> %p\n", matches);
+                    append_match(&matches, (const struct relation_match*)&match);
+                    DLOG(">> %p\n", matches);
+                }
+            }
+        }
+    }
+    return matches;
+}
+
+struct relation_algorithm_operations operations = {
+    .name = "equality",
+    .find = relation_equality_find
+};