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 <vadi...@gmail.com>
---
 trafgen.c       |  9 +++++++++
 trafgen_conf.h  |  7 +++++++
 trafgen_proto.c | 32 ++++++++++++++++++++++++++++++++
 trafgen_proto.h | 15 +++++++++++++++
 4 files changed, 63 insertions(+)

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..0a53ead 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 */
-- 
2.9.2

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