1 files changed, 213 insertions, 0 deletions
diff --git a/src/detect-http-ua.c b/src/detect-http-ua.c
new file mode 100644
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--- /dev/null
+++ b/src/detect-http-ua.c
@@ -0,0 +1,213 @@
+/* Copyright (C) 2007-2018 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.
+ */
+
+/**
+ * \ingroup httplayer
+ *
+ * @{
+ */
+
+
+/**
+ * \file
+ *
+ * \author Anoop Saldanha <anoopsaldanha@gmail.com>
+ *
+ * Implements support for the http_user_agent keyword.
+ */
+
+#include "suricata-common.h"
+#include "threads.h"
+#include "decode.h"
+
+#include "detect.h"
+#include "detect-parse.h"
+#include "detect-engine.h"
+#include "detect-engine-mpm.h"
+#include "detect-engine-state.h"
+#include "detect-engine-prefilter.h"
+#include "detect-content.h"
+#include "detect-pcre.h"
+
+#include "flow.h"
+#include "flow-var.h"
+#include "flow-util.h"
+
+#include "util-debug.h"
+#include "util-unittest.h"
+#include "util-unittest-helper.h"
+#include "util-spm.h"
+
+#include "app-layer.h"
+#include "app-layer-parser.h"
+
+#include "app-layer-htp.h"
+#include "stream-tcp.h"
+#include "detect-http-ua.h"
+
+static int DetectHttpUASetup(DetectEngineCtx *, Signature *, const char *);
+#ifdef UNITTESTS
+static void DetectHttpUARegisterTests(void);
+#endif
+static int g_http_ua_buffer_id = 0;
+static int DetectHttpUserAgentSetup(DetectEngineCtx *, Signature *, const char *);
+static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms,
+        Flow *_f, const uint8_t _flow_flags,
+        void *txv, const int list_id);
+static InspectionBuffer *GetData2(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms, Flow *_f, const uint8_t _flow_flags, void *txv,
+        const int list_id);
+
+/**
+ * \brief Registers the keyword handlers for the "http_user_agent" keyword.
+ */
+void DetectHttpUARegister(void)
+{
+    /* http_user_agent content modifier */
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].name = "http_user_agent";
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].desc = "content modifier to match only on the HTTP User-Agent header";
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].url = "/rules/http-keywords.html#http-user-agent";
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].Setup = DetectHttpUASetup;
+#ifdef UNITTESTS
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].RegisterTests = DetectHttpUARegisterTests;
+#endif
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].flags |= SIGMATCH_NOOPT;
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].flags |= SIGMATCH_INFO_CONTENT_MODIFIER;
+    sigmatch_table[DETECT_AL_HTTP_USER_AGENT].alternative = DETECT_HTTP_UA;
+
+    /* http.user_agent sticky buffer */
+    sigmatch_table[DETECT_HTTP_UA].name = "http.user_agent";
+    sigmatch_table[DETECT_HTTP_UA].desc = "sticky buffer to match specifically and only on the HTTP User Agent buffer";
+    sigmatch_table[DETECT_HTTP_UA].url = "/rules/http-keywords.html#http-user-agent";
+    sigmatch_table[DETECT_HTTP_UA].Setup = DetectHttpUserAgentSetup;
+    sigmatch_table[DETECT_HTTP_UA].flags |= SIGMATCH_NOOPT;
+    sigmatch_table[DETECT_HTTP_UA].flags |= SIGMATCH_INFO_STICKY_BUFFER;
+
+    DetectAppLayerInspectEngineRegister2("http_user_agent", ALPROTO_HTTP1, SIG_FLAG_TOSERVER,
+            HTP_REQUEST_HEADERS, DetectEngineInspectBufferGeneric, GetData);
+
+    DetectAppLayerMpmRegister2("http_user_agent", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,
+            GetData, ALPROTO_HTTP1, HTP_REQUEST_HEADERS);
+
+    DetectAppLayerInspectEngineRegister2("http_user_agent", ALPROTO_HTTP2, SIG_FLAG_TOSERVER,
+            HTTP2StateDataClient, DetectEngineInspectBufferGeneric, GetData2);
+
+    DetectAppLayerMpmRegister2("http_user_agent", SIG_FLAG_TOSERVER, 2, PrefilterGenericMpmRegister,
+            GetData2, ALPROTO_HTTP2, HTTP2StateDataClient);
+
+    DetectBufferTypeSetDescriptionByName("http_user_agent",
+            "http user agent");
+
+    g_http_ua_buffer_id = DetectBufferTypeGetByName("http_user_agent");
+}
+
+/**
+ * \brief The setup function for the http_user_agent keyword for a signature.
+ *
+ * \param de_ctx Pointer to the detection engine context.
+ * \param s      Pointer to the signature for the current Signature being
+ *               parsed from the rules.
+ * \param m      Pointer to the head of the SigMatch for the current rule
+ *               being parsed.
+ * \param arg    Pointer to the string holding the keyword value.
+ *
+ * \retval  0 On success
+ * \retval -1 On failure
+ */
+int DetectHttpUASetup(DetectEngineCtx *de_ctx, Signature *s, const char *arg)
+{
+    return DetectEngineContentModifierBufferSetup(
+            de_ctx, s, arg, DETECT_AL_HTTP_USER_AGENT, g_http_ua_buffer_id, ALPROTO_HTTP1);
+}
+
+/**
+ * \brief this function setup the http.user_agent keyword used in the rule
+ *
+ * \param de_ctx   Pointer to the Detection Engine Context
+ * \param s        Pointer to the Signature to which the current keyword belongs
+ * \param str      Should hold an empty string always
+ *
+ * \retval 0       On success
+ */
+static int DetectHttpUserAgentSetup(DetectEngineCtx *de_ctx, Signature *s, const char *str)
+{
+    if (DetectBufferSetActiveList(de_ctx, s, g_http_ua_buffer_id) < 0)
+        return -1;
+    if (DetectSignatureSetAppProto(s, ALPROTO_HTTP) < 0)
+        return -1;
+    return 0;
+}
+
+static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms, Flow *_f,
+        const uint8_t _flow_flags, void *txv, const int list_id)
+{
+    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
+    if (buffer->inspect == NULL) {
+        htp_tx_t *tx = (htp_tx_t *)txv;
+
+        if (tx->request_headers == NULL)
+            return NULL;
+
+        htp_header_t *h = (htp_header_t *)htp_table_get_c(tx->request_headers,
+                "User-Agent");
+        if (h == NULL || h->value == NULL) {
+            SCLogDebug("HTTP UA header not present in this request");
+            return NULL;
+        }
+
+        const uint32_t data_len = bstr_len(h->value);
+        const uint8_t *data = bstr_ptr(h->value);
+
+        InspectionBufferSetup(det_ctx, list_id, buffer, data, data_len);
+        InspectionBufferApplyTransforms(buffer, transforms);
+    }
+
+    return buffer;
+}
+
+static InspectionBuffer *GetData2(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms, Flow *_f, const uint8_t _flow_flags, void *txv,
+        const int list_id)
+{
+    SCEnter();
+
+    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
+    if (buffer->inspect == NULL) {
+        uint32_t b_len = 0;
+        const uint8_t *b = NULL;
+
+        if (rs_http2_tx_get_useragent(txv, &b, &b_len) != 1)
+            return NULL;
+        if (b == NULL || b_len == 0)
+            return NULL;
+
+        InspectionBufferSetup(det_ctx, list_id, buffer, b, b_len);
+        InspectionBufferApplyTransforms(buffer, transforms);
+    }
+
+    return buffer;
+}
+
+#ifdef UNITTESTS
+#include "tests/detect-http-user-agent.c"
+#endif /* UNITTESTS */
+
+/**
+ * @}
+ */