1 files changed, 218 insertions, 0 deletions
diff --git a/src/detect-distance.c b/src/detect-distance.c
new file mode 100644
index 0000000..1ed66b1
--- /dev/null
+++ b/src/detect-distance.c
@@ -0,0 +1,218 @@
+/* Copyright (C) 2007-2023 Open Information Security Foundation
+ *
+ * You can copy, redistribute or modify this Program under the terms of
+ * the GNU General Public License version 2 as published by the Free
+ * Software Foundation.
+ *
+ * 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
+ * version 2 along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+/**
+ * \file
+ *
+ * \author Victor Julien <victor@inliniac.net>
+ * \author Anoop Saldanha <anoopsaldanha@gmail.com>
+ *
+ * Implements the distance keyword
+ */
+
+#include "suricata-common.h"
+
+#include "decode.h"
+
+#include "detect.h"
+#include "detect-parse.h"
+#include "detect-engine.h"
+#include "app-layer.h"
+
+#include "detect-content.h"
+#include "detect-uricontent.h"
+#include "detect-pcre.h"
+#include "detect-byte.h"
+#include "detect-byte-extract.h"
+#include "detect-distance.h"
+
+#include "flow-var.h"
+
+#include "util-byte.h"
+#include "util-debug.h"
+#include "util-unittest.h"
+#include "detect-bytejump.h"
+#include "util-unittest-helper.h"
+
+static int DetectDistanceSetup(DetectEngineCtx *, Signature *, const char *);
+#ifdef UNITTESTS
+static void DetectDistanceRegisterTests(void);
+#endif
+
+void DetectDistanceRegister(void)
+{
+    sigmatch_table[DETECT_DISTANCE].name = "distance";
+    sigmatch_table[DETECT_DISTANCE].desc = "indicates a relation between this content keyword and the content preceding it";
+    sigmatch_table[DETECT_DISTANCE].url = "/rules/payload-keywords.html#distance";
+    sigmatch_table[DETECT_DISTANCE].Match = NULL;
+    sigmatch_table[DETECT_DISTANCE].Setup = DetectDistanceSetup;
+    sigmatch_table[DETECT_DISTANCE].Free  = NULL;
+#ifdef UNITTESTS
+    sigmatch_table[DETECT_DISTANCE].RegisterTests = DetectDistanceRegisterTests;
+#endif
+}
+
+static int DetectDistanceSetup (DetectEngineCtx *de_ctx, Signature *s,
+        const char *distancestr)
+{
+    const char *str = distancestr;
+
+    /* retrieve the sm to apply the distance against */
+    SigMatch *pm = DetectGetLastSMFromLists(s, DETECT_CONTENT, -1);
+    if (pm == NULL) {
+        SCLogError("distance needs "
+                   "preceding content, uricontent option, http_client_body, "
+                   "http_server_body, http_header option, http_raw_header option, "
+                   "http_method option, http_cookie, http_raw_uri, "
+                   "http_stat_msg, http_stat_code, http_user_agent or "
+                   "file_data/dce_stub_data sticky buffer option");
+        return -1;
+    }
+
+    /* verify other conditions */
+    DetectContentData *cd = (DetectContentData *)pm->ctx;
+    if (cd->flags & DETECT_CONTENT_DISTANCE) {
+        SCLogError("can't use multiple distances for the same content.");
+        return -1;
+    }
+    if ((cd->flags & DETECT_CONTENT_DEPTH) || (cd->flags & DETECT_CONTENT_OFFSET)) {
+        SCLogError("can't use a relative "
+                   "keyword like within/distance with a absolute "
+                   "relative keyword like depth/offset for the same "
+                   "content.");
+        return -1;
+    }
+    if (cd->flags & DETECT_CONTENT_NEGATED && cd->flags & DETECT_CONTENT_FAST_PATTERN) {
+        SCLogError("can't have a relative "
+                   "negated keyword set along with a fast_pattern");
+        return -1;
+    }
+    if (cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) {
+        SCLogError("can't have a relative "
+                   "keyword set along with a fast_pattern:only;");
+        return -1;
+    }
+    if (str[0] != '-' && isalpha((unsigned char)str[0])) {
+        DetectByteIndexType index;
+        if (!DetectByteRetrieveSMVar(str, s, &index)) {
+            SCLogError("unknown byte_ keyword var "
+                       "seen in distance - %s",
+                    str);
+            return -1;
+        }
+        cd->distance = index;
+        cd->flags |= DETECT_CONTENT_DISTANCE_VAR;
+    } else {
+        if ((StringParseI32RangeCheck(&cd->distance, 0, 0, str, -DETECT_CONTENT_VALUE_MAX,
+                     DETECT_CONTENT_VALUE_MAX) < 0)) {
+            SCLogError("invalid value for distance: %s", str);
+            return -1;
+        }
+    }
+    cd->flags |= DETECT_CONTENT_DISTANCE;
+
+    SigMatch *prev_pm = DetectGetLastSMByListPtr(s, pm->prev,
+            DETECT_CONTENT, DETECT_PCRE, -1);
+    if (prev_pm == NULL) {
+        return 0;
+    }
+
+    if (prev_pm->type == DETECT_CONTENT) {
+        DetectContentData *prev_cd = (DetectContentData *)prev_pm->ctx;
+        if (prev_cd->flags & DETECT_CONTENT_FAST_PATTERN_ONLY) {
+            SCLogError("previous keyword "
+                       "has a fast_pattern:only; set. Can't "
+                       "have relative keywords around a fast_pattern "
+                       "only content");
+            return -1;
+        }
+        if ((cd->flags & DETECT_CONTENT_NEGATED) == 0) {
+            prev_cd->flags |= DETECT_CONTENT_DISTANCE_NEXT;
+        } else {
+            prev_cd->flags |= DETECT_CONTENT_RELATIVE_NEXT;
+        }
+    } else if (prev_pm->type == DETECT_PCRE) {
+        DetectPcreData *pd = (DetectPcreData *)prev_pm->ctx;
+        pd->flags |= DETECT_PCRE_RELATIVE_NEXT;
+    }
+
+    return 0;
+}
+
+#ifdef UNITTESTS
+
+static int DetectDistanceTest01(void)
+{
+    DetectEngineCtx *de_ctx = DetectEngineCtxInit();
+    FAIL_IF_NULL(de_ctx);
+    de_ctx->flags |= DE_QUIET;
+
+    Signature *s = DetectEngineAppendSig(de_ctx,
+            "alert tcp any any -> any any (content:\"|AA BB|\"; content:\"|CC DD EE FF 00 11 22 33 "
+            "44 55 66 77 88 99 AA BB CC DD EE|\"; distance: 4; within: 19; sid:1; rev:1;)");
+    FAIL_IF_NULL(s);
+
+    SigMatch *sm = de_ctx->sig_list->init_data->smlists[DETECT_SM_LIST_PMATCH];
+    FAIL_IF_NULL(sm);
+
+    sm = sm->next;
+    FAIL_IF_NULL(sm);
+
+    DetectContentData *co = (DetectContentData *)sm->ctx;
+    FAIL_IF_NULL(co);
+
+    FAIL_IF_NOT(co->distance = 4);
+
+    /* within needs to be 23: distance + content_len as Snort auto fixes this */
+    FAIL_IF_NOT(co->within = 19);
+
+    DetectEngineCtxFree(de_ctx);
+
+    PASS;
+}
+
+/**
+ * \test DetectDistanceTestPacket01 is a test to check matches of
+ * distance works, if the previous keyword is byte_jump and content
+ * (bug 163)
+ */
+static int DetectDistanceTestPacket01 (void)
+{
+    uint8_t buf[] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00 };
+    uint16_t buflen = sizeof(buf);
+    Packet *p = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
+
+    FAIL_IF_NULL(p);
+    char sig[] = "alert tcp any any -> any any (msg:\"suricata test\"; "
+                    "byte_jump:1,2; content:\"|00|\"; "
+                    "within:1; distance:2; sid:98711212; rev:1;)";
+
+    p->flowflags = FLOW_PKT_ESTABLISHED | FLOW_PKT_TOCLIENT;
+    FAIL_IF_NOT(UTHPacketMatchSig(p, sig));
+
+    UTHFreePacket(p);
+
+    PASS;
+}
+
+static void DetectDistanceRegisterTests(void)
+{
+    UtRegisterTest("DetectDistanceTest01 -- distance / within mix",
+                   DetectDistanceTest01);
+    UtRegisterTest("DetectDistanceTestPacket01", DetectDistanceTestPacket01);
+}
+#endif /* UNITTESTS */