trafgen: proto: Update field value at runtime

Add basic infrastructure for update proto field value at runtime by
dynamic field function.

Extended 'struct packet_dyn' with proto fields which has dynamically
changing values at runtime.

Added 'field_changed' callback for proto header which may be used for
check if csum updating is needed. This callback is called after field
was changed at runtime.

Added 'packet_update' callback to let proto header know when to apply
final proto header changes at runtime (e.g. - csum update).

Signed-off-by: Vadim Kochan <vadim4j@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

4 files changed, 63 insertions, 0 deletions

diff --git a/trafgen.c b/trafgen.c
index b76b5d7..553dfa5 100644
--- a/trafgen.c
+++ b/trafgen.c
@@ -619,6 +619,15 @@ static inline void packet_apply_dyn_elements(int idx)
 		apply_randomizer(idx);
 		apply_csum16(idx);
 	}
+
+	if (packet_dyn_has_fields(&packet_dyn[idx])) {
+		uint32_t i;
+
+		for (i = 0; i < packet_dyn[idx].flen; i++)
+			proto_field_dyn_apply(packet_dyn[idx].fields[i]);
+
+		proto_packet_update(idx);
+	}
 }
 
 static void xmit_slowpath_or_die(struct ctx *ctx, unsigned int cpu, unsigned long orig_num)
diff --git a/trafgen_conf.h b/trafgen_conf.h
index 934f8fe..61da012 100644
--- a/trafgen_conf.h
+++ b/trafgen_conf.h
@@ -49,6 +49,8 @@ struct packet_dyn {
 	size_t rlen;
 	struct csum16 *csum;
 	size_t slen;
+	struct proto_field **fields;
+	size_t flen;
 };
 
 static inline bool packet_dyn_has_elems(struct packet_dyn *p)
@@ -61,6 +63,11 @@ static inline bool packet_dyn_has_only_csums(struct packet_dyn *p)
 	return (p->clen == 0 && p->rlen == 0 && p->slen);
 }
 
+static inline bool packet_dyn_has_fields(struct packet_dyn *p)
+{
+	return p->flen;
+}
+
 extern void compile_packets_str(char *str, bool verbose, unsigned int cpu);
 extern void compile_packets(char *file, bool verbose, unsigned int cpu,
 			    bool invoke_cpp, char *const cpp_argv[]);
diff --git a/trafgen_proto.c b/trafgen_proto.c
index d976c14..96fd6da 100644
--- a/trafgen_proto.c
+++ b/trafgen_proto.c
@@ -409,6 +409,19 @@ void protos_init(const char *dev)
 	protos_l4_init();
 }
 
+void proto_packet_update(uint32_t idx)
+{
+	struct packet *pkt = packet_get(idx);
+	ssize_t i;
+
+	for (i = pkt->headers_count - 1; i >= 0; i--) {
+		struct proto_hdr *hdr = pkt->headers[i];
+
+		if (hdr->ops->packet_update)
+			hdr->ops->packet_update(hdr);
+	}
+}
+
 void proto_packet_finish(void)
 {
 	struct proto_hdr **headers = current_packet()->headers;
@@ -424,3 +437,22 @@ void proto_packet_finish(void)
 			ops->packet_finish(hdr);
 	}
 }
+
+void proto_field_func_add(struct proto_hdr *hdr, uint32_t fid,
+			  struct proto_field_func *func)
+{
+	struct proto_field *field = proto_field_by_id(hdr, fid);
+
+	bug_on(!func);
+
+	field->func.update_field = func->update_field;
+}
+
+void proto_field_dyn_apply(struct proto_field *field)
+{
+	if (field->func.update_field)
+		field->func.update_field(field);
+
+	if (field->hdr->ops->field_changed)
+		field->hdr->ops->field_changed(field);
+}
diff --git a/trafgen_proto.h b/trafgen_proto.h
index 9716aa2..6cdc51f 100644
--- a/trafgen_proto.h
+++ b/trafgen_proto.h
@@ -27,6 +27,7 @@ enum proto_layer {
 	PROTO_L4,
 };
 
+struct proto_field;
 struct proto_hdr;
 
 struct proto_ops {
@@ -35,7 +36,9 @@ struct proto_ops {
 
 	void (*header_init)(struct proto_hdr *hdr);
 	void (*header_finish)(struct proto_hdr *hdr);
+	void (*field_changed)(struct proto_field *field);
 	void (*packet_finish)(struct proto_hdr *hdr);
+	void (*packet_update)(struct proto_hdr *hdr);
 	void (*set_next_proto)(struct proto_hdr *hdr, enum proto_id pid);
 };
 
@@ -48,6 +51,10 @@ struct proto_hdr {
 	size_t len;
 };
 
+struct proto_field_func {
+	void (*update_field)(struct proto_field *field);
+};
+
 struct proto_field {
 	uint32_t id;
 	size_t len;
@@ -56,6 +63,7 @@ struct proto_field {
 	/* might be negative (e.g. VLAN TPID field) */
 	int16_t offset;
 
+	struct proto_field_func func;
 	bool is_set;
 	uint16_t pkt_offset;
 	struct proto_hdr *hdr;
@@ -67,6 +75,8 @@ extern void proto_ops_register(const struct proto_ops *ops);
 extern struct proto_hdr *proto_header_push(enum proto_id pid);
 extern void proto_header_finish(struct proto_hdr *hdr);
 extern void proto_packet_finish(void);
+extern void proto_packet_update(uint32_t idx);
+
 extern struct proto_hdr *proto_lower_default_add(struct proto_hdr *hdr,
 						 enum proto_id pid);
 
@@ -113,4 +123,9 @@ extern void proto_field_set_default_dev_ipv4(struct proto_hdr *hdr, uint32_t fid
 extern void proto_field_set_dev_ipv6(struct proto_hdr *hdr, uint32_t fid);
 extern void proto_field_set_default_dev_ipv6(struct proto_hdr *hdr, uint32_t fid);
 
+extern void proto_field_dyn_apply(struct proto_field *field);
+
+extern void proto_field_func_add(struct proto_hdr *hdr, uint32_t fid,
+				 struct proto_field_func *func);
+
 #endif /* TRAFGEN_PROTO_H */