flow: add callbacks for flow init and flow updates

Adds user registerable callbacks for flow initialization and flow
update.

Some plugins, such as other DPI libraries like nDPI need a way to hook
into these flow lifecycle events.

Ticket: #7319
Ticket: #7320

src/Makefile.am

@@ -329,6 +329,7 @@ noinst_HEADERS = \
 	feature.h \
 	flow-bit.h \
 	flow-bypass.h \
+	flow-callbacks.h \
 	flow.h \
 	flow-hash.h \
 	flow-manager.h \
@@ -902,6 +903,7 @@ libsuricata_c_a_SOURCES = \
 	feature.c \
 	flow-bit.c \
 	flow-bypass.c \
+	flow-callbacks.c \
 	flow.c \
 	flow-hash.c \
 	flow-manager.c \

src/flow-callbacks.c

@@ -0,0 +1,88 @@
+/* Copyright (C) 2024 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 "flow-callbacks.h"
+
+typedef struct FlowInitCallback_ {
+    SCFlowInitCallbackFn fn;
+    struct FlowInitCallback_ *next;
+} FlowInitCallback;
+
+static FlowInitCallback *init_callbacks = NULL;
+
+typedef struct FlowUpdateCallback_ {
+    SCFlowUpdateCallbackFn fn;
+    struct FlowUpdateCallback_ *next;
+} FlowUpdateCallback;
+
+static FlowUpdateCallback *update_callbacks = NULL;
+
+bool SCFlowRegisterInitCallback(SCFlowInitCallbackFn fn)
+{
+    FlowInitCallback *cb = SCCalloc(1, sizeof(*cb));
+    if (cb == NULL) {
+        return false;
+    }
+    cb->fn = fn;
+    if (init_callbacks == NULL) {
+        init_callbacks = cb;
+    } else {
+        FlowInitCallback *current = init_callbacks;
+        while (current->next != NULL) {
+            current = current->next;
+        }
+        current->next = cb;
+    }
+    return true;
+}
+
+void SCFlowRunInitCallbacks(Flow *f, const Packet *p)
+{
+    FlowInitCallback *cb = init_callbacks;
+    while (cb != NULL) {
+        cb->fn(f, p);
+        cb = cb->next;
+    }
+}
+
+bool SCFlowRegisterUpdateCallback(SCFlowUpdateCallbackFn fn)
+{
+    FlowUpdateCallback *cb = SCCalloc(1, sizeof(*cb));
+    if (cb == NULL) {
+        return false;
+    }
+    cb->fn = fn;
+    if (update_callbacks == NULL) {
+        update_callbacks = cb;
+    } else {
+        FlowUpdateCallback *current = update_callbacks;
+        while (current->next != NULL) {
+            current = current->next;
+        }
+        current->next = cb;
+    }
+    return true;
+}
+
+void SCFlowRunUpdateCallbacks(Flow *f, Packet *p, ThreadVars *tv)
+{
+    FlowUpdateCallback *cb = update_callbacks;
+    while (cb != NULL) {
+        cb->fn(f, p, tv);
+        cb = cb->next;
+    }
+}

src/flow-callbacks.h

@@ -0,0 +1,60 @@
+/* Copyright (C) 2024 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.
+ */
+
+#ifndef SURICATA_FLOW_CALLBACKS_H
+#define SURICATA_FLOW_CALLBACKS_H
+
+#include "suricata-common.h"
+#include "flow.h"
+
+typedef void (*SCFlowInitCallbackFn)(Flow *f, const Packet *p);
+
+/** \brief Register a flow init callback.
+ *
+ * Register a user provided function to be called every time a flow is
+ * initialized for use.
+ *
+ * \returns true if callback was registered, otherwise false if the
+ *     callback could not be registered due to memory allocation error.
+ */
+bool SCFlowRegisterInitCallback(SCFlowInitCallbackFn fn);
+
+/** \internal
+ *
+ * Run all registered flow init callbacks.
+ */
+void SCFlowRunInitCallbacks(Flow *f, const Packet *p);
+
+typedef void (*SCFlowUpdateCallbackFn)(Flow *f, Packet *p, ThreadVars *tv);
+
+/** \brief Register a flow update callback.
+ *
+ * Register a user provided function to be called everytime a flow is
+ * updated.
+ *
+ * \returns true if callback was registered, otherwise false if the
+ *     callback could not be registered due to memory allocation error.
+ */
+bool SCFlowRegisterUpdateCallback(SCFlowUpdateCallbackFn fn);
+
+/** \internal
+ *
+ * Run all registered flow update callbacks.
+ */
+void SCFlowRunUpdateCallbacks(Flow *f, Packet *p, ThreadVars *tv);
+
+#endif /* SURICATA_FLOW_CALLBACKS_H */

src/flow-util.c

@@ -29,6 +29,7 @@
 #include "flow.h"
 #include "flow-private.h"
 #include "flow-util.h"
+#include "flow-callbacks.h"
 #include "flow-var.h"
 #include "app-layer.h"
 
@@ -203,6 +204,8 @@ void FlowInit(Flow *f, const Packet *p)
         FlowSetStorageById(f, MacSetGetFlowStorageID(), ms);
     }
 
+    SCFlowRunInitCallbacks(f, p);
+
     SCReturn;
 }
 

src/flow.c

@@ -44,6 +44,7 @@
 #include "flow-storage.h"
 #include "flow-bypass.h"
 #include "flow-spare-pool.h"
+#include "flow-callbacks.h"
 
 #include "stream-tcp-private.h"
 
@@ -503,6 +504,8 @@ void FlowHandlePacketUpdate(Flow *f, Packet *p, ThreadVars *tv, DecodeThreadVars
         SCLogDebug("setting FLOW_NOPAYLOAD_INSPECTION flag on flow %p", f);
         DecodeSetNoPayloadInspectionFlag(p);
     }
+
+    SCFlowRunUpdateCallbacks(f, p, tv);
 }
 
 /** \brief Entry point for packet flow handling