trafgen: l7: Add DNS header generation API

Add trafgen_l7.c module with DNS proto header generation with
support of filling DNS query/answer/authority/additional sections
as sub headers.

Introcuded new concept as 'sub header' which is needed to easy handle
DNS sections which might be added on-demand, and to simplify using
sub-header as regular header with a fields, offset, etc. There is a
parent header which contains array of pointers of sub-headers, and the
array is ordered as they are located in the parent header. The
sub-headers mostly encapsulated by the parent header which 'knows'
the semantic of them. The new proto_hdr->push_sub_header(...) callback
was added to tell the parent header to push the sub-header's fields,
sub-header also may have proto_ops which must be filled by the parent.
This sub-header concept might be used in the future if it will be needed
to support DHCP, WLAN headers.

There are 4 kinds of DNS sub-headers - query, answer, authority,
additional. 'id' of each sub-header is used to only differentiate these
types of sections. These sections have strict order inside DNS header,
and there was added the proto_hdr_move_sub_header(...) to sort them in
required order.

Actually there are only 2 proto_hdr's which describes 4 DNS sections -
query & rrecord, because rrecord covers another 3 - answer, auhority,
additional which have the same layout.

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

1 files changed, 17 insertions, 2 deletions

diff --git a/trafgen_proto.h b/trafgen_proto.h
index 94eb4e7..f3d07ba 100644
--- a/trafgen_proto.h
+++ b/trafgen_proto.h
@@ -19,6 +19,7 @@ enum proto_id {
 	PROTO_ICMP6,
 	PROTO_UDP,
 	PROTO_TCP,
+	PROTO_DNS,
 	__PROTO_MAX,
 };
 
@@ -27,6 +28,7 @@ enum proto_layer {
 	PROTO_L2,
 	PROTO_L3,
 	PROTO_L4,
+	PROTO_L7,
 };
 
 struct proto_field;
@@ -38,6 +40,7 @@ struct proto_ops {
 
 	void (*header_init)(struct proto_hdr *hdr);
 	void (*header_finish)(struct proto_hdr *hdr);
+	void (*push_sub_header)(struct proto_hdr *hdr, struct proto_hdr *sub_hdr);
 	void (*field_changed)(struct proto_field *field);
 	void (*packet_finish)(struct proto_hdr *hdr);
 	void (*packet_update)(struct proto_hdr *hdr);
@@ -46,12 +49,16 @@ struct proto_ops {
 
 struct proto_hdr {
 	const struct proto_ops *ops;
+	struct proto_hdr *parent;
+	struct proto_hdr **sub_headers;
+	uint32_t sub_headers_count;
 	uint16_t pkt_offset;
 	uint32_t pkt_id;
 	uint32_t index;
 	struct proto_field *fields;
 	size_t fields_count;
 	bool is_csum_valid;
+	uint32_t id;
 	size_t len;
 };
 
@@ -95,6 +102,10 @@ 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_hdr_push_sub_header(struct proto_hdr *hdr, int id);
+extern void proto_hdr_move_sub_header(struct proto_hdr *hdr, struct proto_hdr *from,
+				      struct proto_hdr *to);
+
 extern struct proto_hdr *proto_lower_default_add(struct proto_hdr *hdr,
 						 enum proto_id pid);
 
@@ -142,6 +153,9 @@ extern void proto_hdr_field_set_default_dev_ipv4(struct proto_hdr *hdr, uint32_t
 extern void proto_hdr_field_set_dev_ipv6(struct proto_hdr *hdr, uint32_t fid);
 extern void proto_hdr_field_set_default_dev_ipv6(struct proto_hdr *hdr, uint32_t fid);
 
+extern void proto_hdr_field_set_string(struct proto_hdr *hdr, uint32_t fid, const char *str);
+extern void proto_hdr_field_set_default_string(struct proto_hdr *hdr, uint32_t fid, const char *str);
+
 extern void proto_field_dyn_apply(struct proto_field *field);
 
 extern struct proto_field *proto_hdr_field_by_id(struct proto_hdr *hdr, uint32_t fid);
@@ -155,8 +169,9 @@ extern void proto_field_set_u32(struct proto_field *field, uint32_t val);
 extern uint32_t proto_field_get_u32(struct proto_field *field);
 extern void proto_field_set_be16(struct proto_field *field, uint16_t val);
 extern void proto_field_set_be32(struct proto_field *field, uint32_t val);
-extern void proto_field_set_bytes(struct proto_field *field, const uint8_t *bytes,
-				  size_t len);
+extern void proto_field_set_bytes(struct proto_field *field, const uint8_t *bytes, size_t len);
+extern void proto_field_set_string(struct proto_field *field, const char *str);
+extern void proto_field_set_default_string(struct proto_field *field, const char *str);
 
 extern void proto_field_func_add(struct proto_field *field,
 				 struct proto_field_func *func);