detect: add igmp.hdr keyword

src/Makefile.am

@@ -228,6 +228,7 @@ noinst_HEADERS = \
 	detect-icmpv6hdr.h \
 	detect-icode.h \
 	detect-id.h \
+	detect-igmphdr.h \
 	detect-ipaddr.h \
 	detect-ipopts.h \
 	detect-ipproto.h \
@@ -806,6 +807,7 @@ libsuricata_c_a_SOURCES = \
 	detect-icmpv6hdr.c \
 	detect-icode.c \
 	detect-id.c \
+	detect-igmphdr.c \
 	detect-ipaddr.c \
 	detect-ipopts.c \
 	detect-ipproto.c \
@@ -1174,6 +1176,7 @@ EXTRA_DIST = \
 	tests/detect-http2.c \
 	tests/detect-icmpv6-mtu.c \
 	tests/detect-icmpv6hdr.c \
+	tests/detect-igmphdr.c \
 	tests/detect-template.c \
 	tests/detect-transform-pcrexform.c \
 	tests/detect-ttl.c \

src/detect-engine-register.c

@@ -154,6 +154,7 @@
 #include "detect-icmp-id.h"
 #include "detect-icmp-seq.h"
 #include "detect-icmpv4hdr.h"
+#include "detect-igmphdr.h"
 #include "detect-dce-iface.h"
 #include "detect-dce-opnum.h"
 #include "detect-dce-stub-data.h"
@@ -664,6 +665,7 @@ void SigTableSetup(void)
     DetectIcmpIdRegister();
     DetectIcmpSeqRegister();
     DetectIcmpv4HdrRegister();
+    DetectIGMPHdrRegister();
     DetectDceIfaceRegister();
     DetectDceOpnumRegister();
     DetectDceStubDataRegister();

src/detect-engine-register.h

@@ -49,6 +49,7 @@ enum DetectKeywordId {
     DETECT_ICMP_ID,
     DETECT_ICMP_SEQ,
     DETECT_ICMPV4HDR,
+    DETECT_IGMPHDR,
     DETECT_DSIZE,
 
     DETECT_FLOW,

src/detect-igmphdr.c

@@ -0,0 +1,123 @@
+/* Copyright (C) 2026 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
+ *
+ */
+
+#include "suricata-common.h"
+
+#include "detect.h"
+#include "detect-engine.h"
+#include "detect-engine-buffer.h"
+#include "detect-engine-mpm.h"
+#include "detect-igmphdr.h"
+#include "detect-engine-prefilter.h"
+
+/* prototypes */
+static int DetectIGMPHdrSetup(DetectEngineCtx *, Signature *, const char *);
+#ifdef UNITTESTS
+void DetectIGMPHdrRegisterTests(void);
+#endif
+
+static int g_igmphdr_buffer_id = 0;
+
+static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms, Packet *p, const int list_id);
+
+/**
+ * \brief Registration function for igmp.hdr: keyword
+ */
+void DetectIGMPHdrRegister(void)
+{
+    sigmatch_table[DETECT_IGMPHDR].name = "igmp.hdr";
+    sigmatch_table[DETECT_IGMPHDR].desc = "sticky buffer to match on the IGMP header";
+    sigmatch_table[DETECT_IGMPHDR].url = "/rules/header-keywords.html#igmp-hdr";
+    sigmatch_table[DETECT_IGMPHDR].Setup = DetectIGMPHdrSetup;
+    sigmatch_table[DETECT_IGMPHDR].flags |= SIGMATCH_NOOPT | SIGMATCH_INFO_STICKY_BUFFER;
+#ifdef UNITTESTS
+    sigmatch_table[DETECT_IGMPHDR].RegisterTests = DetectIGMPHdrRegisterTests;
+#endif
+
+    g_igmphdr_buffer_id = DetectBufferTypeRegister("igmp.hdr");
+    BUG_ON(g_igmphdr_buffer_id < 0);
+
+    DetectBufferTypeSupportsPacket("igmp.hdr");
+
+    DetectPktMpmRegister("igmp.hdr", 2, PrefilterGenericMpmPktRegister, GetData);
+
+    DetectPktInspectEngineRegister("igmp.hdr", GetData, DetectEngineInspectPktBufferGeneric);
+}
+
+/**
+ * \brief setup igmp.hdr sticky buffer
+ *
+ * \param de_ctx pointer to the Detection Engine Context
+ * \param s pointer to the Current Signature
+ * \param _unused unused
+ *
+ * \retval 0 on Success
+ * \retval -1 on Failure
+ */
+static int DetectIGMPHdrSetup(DetectEngineCtx *de_ctx, Signature *s, const char *_unused)
+{
+    if (!(DetectProtoContainsProto(&s->proto, IPPROTO_IGMP)))
+        return -1;
+
+    s->proto.flags |= DETECT_PROTO_IPV4;
+    s->flags |= SIG_FLAG_REQUIRE_PACKET;
+
+    if (SCDetectBufferSetActiveList(de_ctx, s, g_igmphdr_buffer_id) < 0)
+        return -1;
+
+    return 0;
+}
+
+static InspectionBuffer *GetData(DetectEngineThreadCtx *det_ctx,
+        const DetectEngineTransforms *transforms, Packet *p, const int list_id)
+{
+    SCEnter();
+
+    if (!PacketIsIGMP(p)) {
+        SCReturnPtr(NULL, "InspectionBuffer");
+    }
+
+    InspectionBuffer *buffer = InspectionBufferGet(det_ctx, list_id);
+    if (buffer->inspect == NULL) {
+        const IGMPHdr *igmph = PacketGetIGMP(p);
+        const uint16_t hlen = p->l4.vars.igmp.hlen;
+        if (((uint8_t *)igmph + (ptrdiff_t)hlen) >
+                ((uint8_t *)GET_PKT_DATA(p) + (ptrdiff_t)GET_PKT_LEN(p))) {
+            SCLogDebug("data out of range: %p > %p", ((uint8_t *)igmph + (ptrdiff_t)hlen),
+                    ((uint8_t *)GET_PKT_DATA(p) + (ptrdiff_t)GET_PKT_LEN(p)));
+            SCReturnPtr(NULL, "InspectionBuffer");
+        }
+
+        const uint32_t data_len = hlen;
+        const uint8_t *data = (const uint8_t *)igmph;
+
+        InspectionBufferSetupAndApplyTransforms(
+                det_ctx, list_id, buffer, data, data_len, transforms);
+    }
+
+    SCReturnPtr(buffer, "InspectionBuffer");
+}
+
+#ifdef UNITTESTS
+#include "tests/detect-igmphdr.c"
+#endif

src/detect-igmphdr.h

@@ -0,0 +1,27 @@
+/* Copyright (C) 2026 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
+ */
+
+#ifndef _DETECT_IGMPHDR_H
+#define _DETECT_IGMPHDR_H
+
+void DetectIGMPHdrRegister(void);
+
+#endif /* _DETECT_IGMPHDR_H */

src/tests/detect-igmphdr.c

@@ -0,0 +1,45 @@
+/* Copyright (C) 2026 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.
+ */
+
+#include "../suricata-common.h"
+
+#include "../detect.h"
+#include "../detect-parse.h"
+
+#include "../detect-igmphdr.h"
+
+#include "../util-unittest.h"
+
+static int DetectIGMPHdrParseTest01(void)
+{
+    DetectEngineCtx *de_ctx = DetectEngineCtxInit();
+    FAIL_IF_NULL(de_ctx);
+
+    FAIL_IF_NULL(DetectEngineAppendSig(
+            de_ctx, "alert igmp any any -> any any (igmp.hdr; content:\"A\"; sid:1; rev:1;)"));
+
+    DetectEngineCtxFree(de_ctx);
+    PASS;
+}
+
+/**
+ * \brief register tests
+ */
+void DetectIGMPHdrRegisterTests(void)
+{
+    UtRegisterTest("DetectIGMPHdrParseTest01", DetectIGMPHdrParseTest01);
+}