trafgen: parser: Add TCP header generation function

Add a function 'tcp()' to generate TCP headers from the trafgen
configuration language.

Fields supported:

    sp|sport     TCP source port (default 0)
    dp|dport     TCP destination port (default 0)
    seq          Sequence number (default: 0)
    aseq|ackseq  Acknowledgement number (default 0)
    doff|hlen    Header length/data offset (default: 5)
    cwr          Congestion Window Reduced flag (default: 0)
    ece|ecn      ECN-Echo flag (default: 0)
    urg          Urgent flag (default: 0)
    ack          Acknowledgement flag (default: 0)
    psh          Push flag (default: 0)
    rst          Reset flag (default: 0)
    syn          Synchronize flag (default: 0)
    fin          Finish flag (default: 0)
    win|window   Receive window size (default: 0)
    csum         Checksum field (calculated automatically)
    urgptr       Urgent pointer (default: 0)

Example (SYN on port 80/http):

    { tcp(dport=80, syn, window=5840) }

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

5 files changed, 202 insertions, 1 deletions

diff --git a/trafgen.8 b/trafgen.8
index 48a252c..207cfc5 100644
--- a/trafgen.8
+++ b/trafgen.8
@@ -428,6 +428,65 @@ By default, if the lower level header is Ethernet, its EtherType field is set to
 By default, if the lower level header is IPv4, its protocol field is set to
 0x11 (UDP).
 
+.I TCP
+:
+.B tcp(sp=<number>, dp=<number>, seq=<number>, aseq|ackseq=<number>, doff|hlen=<number>,
+.B cwr, ece|ecn, urg, ack, psh, rst, syn, fin, win|window=<number>, csum=<number>,
+.B urgptr=<number>)
+.sp
+.in +4
+.B sp|sport
+- Source port (default: 0)
+.sp
+.B dp|dport
+- Destination port (default: 0)
+.sp
+.B seq
+- Sequence number (default: 0)
+.sp
+.B aseq|ackseq
+- Acknowledgement number (default: 0)
+.sp
+.B doff|hlen
+- Header size (data offset) in number of 32-bit words (default: 5)
+.sp
+.B cwr
+- Congestion Window Reduced (CWR) flag (default: 0)
+.sp
+.B ece|ecn
+- ECN-Echo (ECE) flag (default: 0)
+.sp
+.B urg
+- Urgent flag (default: 0)
+.sp
+.B ack
+- Acknowledgement flag (default: 0)
+.sp
+.B psh
+- Push flag (default: 0)
+.sp
+.B rst
+- Reset flag (default: 0)
+.sp
+.B syn
+- Synchronize flag (default: 0)
+.sp
+.B fin
+- Finish flag (default: 0)
+.sp
+.B win|window
+- Receive window size (default: 0)
+.sp
+.B csum
+- Checksum field over IPv4 pseudo header (calculated by default)
+.sp
+.B urgptr
+- Urgent pointer (default: 0)
+.sp
+.in -4
+By default, if the lower level header is IPv4, its protocol field is set to
+0x6 (TCP).
+
 Simple example of a UDP Echo packet:
 .PP
 .in +5
diff --git a/trafgen_l4.c b/trafgen_l4.c
index 286e54a..7f80e74 100644
--- a/trafgen_l4.c
+++ b/trafgen_l4.c
@@ -21,6 +21,26 @@ static struct proto_field udp_fields[] = {
 	{ .id = UDP_CSUM,	.len = 2,	.offset = 6 },
 };
 
+static struct proto_field tcp_fields[] = {
+	{ .id = TCP_SPORT,   .len = 2, .offset = 0 },
+	{ .id = TCP_DPORT,   .len = 2, .offset = 2 },
+	{ .id = TCP_SEQ,     .len = 4, .offset = 4 },
+	{ .id = TCP_ACK_SEQ, .len = 4, .offset = 8 },
+	{ .id = TCP_DOFF,    .len = 2, .offset = 12, .shift = 12, .mask = 0xf000 },
+	/* reserved (4 bits) */
+	{ .id = TCP_CWR,     .len = 2, .offset = 12, .shift = 7, .mask = 0x0080 },
+	{ .id = TCP_ECE,     .len = 2, .offset = 12, .shift = 6, .mask = 0x0040 },
+	{ .id = TCP_URG,     .len = 2, .offset = 12, .shift = 5, .mask = 0x0020 },
+	{ .id = TCP_ACK,     .len = 2, .offset = 12, .shift = 4, .mask = 0x0010 },
+	{ .id = TCP_PSH,     .len = 2, .offset = 12, .shift = 3, .mask = 0x0008 },
+	{ .id = TCP_RST,     .len = 2, .offset = 12, .shift = 2, .mask = 0x0004 },
+	{ .id = TCP_SYN,     .len = 2, .offset = 12, .shift = 1, .mask = 0x0002 },
+	{ .id = TCP_FIN,     .len = 2, .offset = 12, .shift = 0, .mask = 0x0001 },
+	{ .id = TCP_WINDOW,  .len = 2, .offset = 14 },
+	{ .id = TCP_CSUM,    .len = 2, .offset = 16 },
+	{ .id = TCP_URG_PTR, .len = 2, .offset = 18 },
+};
+
 static void udp_header_init(struct proto_hdr *hdr)
 {
 	struct proto_hdr *lower;
@@ -65,7 +85,51 @@ static struct proto_hdr udp_hdr = {
 	.packet_finish  = udp_packet_finish,
 };
 
+static void tcp_header_init(struct proto_hdr *hdr)
+{
+	struct proto_hdr *lower;
+
+	proto_lower_default_add(PROTO_IP4);
+
+	lower = proto_current_header();
+
+	if (lower->id == PROTO_IP4)
+		proto_field_set_default_u8(lower, IP4_PROTO, IPPROTO_TCP);
+
+	proto_header_fields_add(hdr, tcp_fields, array_size(tcp_fields));
+
+	proto_field_set_default_be16(hdr, TCP_DOFF, 5);
+}
+
+static void tcp_packet_finish(struct proto_hdr *hdr)
+{
+	struct proto_hdr *lower = proto_lower_header(hdr);
+	struct packet *pkt = current_packet();
+	uint16_t total_len;
+	uint16_t csum;
+
+	if (proto_field_is_set(hdr, TCP_CSUM))
+		return;
+
+	if (!lower || lower->id != PROTO_IP4)
+		return;
+
+	total_len = pkt->len - hdr->pkt_offset;
+	csum = p4_csum((void *) proto_header_ptr(lower), proto_header_ptr(hdr),
+			total_len, IPPROTO_TCP);
+
+	proto_field_set_be16(hdr, TCP_CSUM, bswap_16(csum));
+}
+
+static struct proto_hdr tcp_hdr = {
+	.id		= PROTO_TCP,
+	.layer		= PROTO_L4,
+	.header_init	= tcp_header_init,
+	.packet_finish  = tcp_packet_finish,
+};
+
 void protos_l4_init(void)
 {
 	proto_header_register(&udp_hdr);
+	proto_header_register(&tcp_hdr);
 }
diff --git a/trafgen_l4.h b/trafgen_l4.h
index 4651009..da73ebc 100644
--- a/trafgen_l4.h
+++ b/trafgen_l4.h
@@ -8,6 +8,25 @@ enum udp_field {
 	UDP_CSUM,
 };
 
+enum tcp_field {
+	TCP_SPORT,
+	TCP_DPORT,
+	TCP_SEQ,
+	TCP_ACK_SEQ,
+	TCP_DOFF,
+	TCP_CWR,
+	TCP_ECE,
+	TCP_URG,
+	TCP_ACK,
+	TCP_PSH,
+	TCP_RST,
+	TCP_SYN,
+	TCP_FIN,
+	TCP_WINDOW,
+	TCP_CSUM,
+	TCP_URG_PTR,
+};
+
 extern void protos_l4_init(void);
 
 #endif /* TRAFGEN_L4_H */
diff --git a/trafgen_lexer.l b/trafgen_lexer.l
index 5ab0815..83e7602 100644
--- a/trafgen_lexer.l
+++ b/trafgen_lexer.l
@@ -143,10 +143,26 @@ ip4_addr	([0-9]+\.[0-9]+\.[0-9]+\.[0-9]+)
 "sp"|"sport"	{ return K_SPORT; }
 "dp"|"dport"	{ return K_DPORT; }
 
+	/* TCP */
+"seq"		{ return K_SEQ; }
+"ackseq"|"aseq"	{ return K_ACK_SEQ; }
+"doff"|hlen	{ return K_DOFF; }
+"cwr"		{ return K_CWR; }
+"ece"|"ecn"	{ return K_ECE; }
+"urg"		{ return K_URG; }
+"ack"		{ return K_ACK; }
+"psh"		{ return K_PSH; }
+"rst"		{ return K_RST; }
+"syn"		{ return K_SYN; }
+"fin"		{ return K_FIN; }
+"win"|"window"	{ return K_WINDOW; }
+"urgptr"	{ return K_URG_PTR; }
+
 "eth"		{ return K_ETH; }
 "arp"		{ return K_ARP; }
 "ip4"|"ipv4"	{ return K_IP4; }
 "udp"		{ return K_UDP; }
+"tcp"		{ return K_TCP; }
 
 [ ]*"-"[ ]*	{ return '-'; }
 [ ]*"+"[ ]*	{ return '+'; }
diff --git a/trafgen_parser.y b/trafgen_parser.y
index e512aed..7387c14 100644
--- a/trafgen_parser.y
+++ b/trafgen_parser.y
@@ -354,11 +354,12 @@ static void proto_add(enum proto_id pid)
 %token K_OPER K_SHA K_SPA K_THA K_TPA K_REQUEST K_REPLY K_PTYPE K_HTYPE
 %token K_PROT K_TTL K_DSCP K_ECN K_TOS K_LEN K_ID K_FLAGS K_FRAG K_IHL K_VER K_CSUM K_DF K_MF
 %token K_SPORT K_DPORT
+%token K_SEQ K_ACK_SEQ K_DOFF K_CWR K_ECE K_URG K_ACK K_PSH K_RST K_SYN K_FIN K_WINDOW K_URG_PTR
 
 %token K_ETH
 %token K_ARP
 %token K_IP4
-%token K_UDP
+%token K_UDP K_TCP
 
 %token ',' '{' '}' '(' ')' '[' ']' ':' '-' '+' '*' '/' '%' '&' '|' '<' '>' '^'
 
@@ -582,6 +583,7 @@ proto
 	| arp_proto { }
 	| ip4_proto { }
 	| udp_proto { }
+	| tcp_proto { }
 	;
 
 eth_proto
@@ -717,6 +719,47 @@ udp
 	: K_UDP	{ proto_add(PROTO_UDP); }
 	;
 
+tcp_proto
+	: tcp '(' tcp_param_list ')' { }
+	;
+
+tcp_param_list
+	: { }
+	| tcp_field { }
+	| tcp_field delimiter tcp_param_list { }
+	;
+
+tcp_field
+	: K_SPORT  skip_white '=' skip_white number
+		{ proto_field_set_be16(hdr, TCP_SPORT, $5); }
+	| K_DPORT  skip_white '=' skip_white number
+		{ proto_field_set_be16(hdr, TCP_DPORT, $5); }
+	| K_SEQ skip_white '=' skip_white number
+		{ proto_field_set_be32(hdr, TCP_SEQ, $5); }
+	| K_ACK_SEQ skip_white '=' skip_white number
+		{ proto_field_set_be32(hdr, TCP_ACK_SEQ, $5); }
+	| K_DOFF skip_white '=' skip_white number
+		{ proto_field_set_be16(hdr, TCP_DOFF, $5); }
+	| K_CWR { proto_field_set_be16(hdr, TCP_CWR, 1); }
+	| K_ECE { proto_field_set_be16(hdr, TCP_ECE, 1); }
+	| K_URG { proto_field_set_be16(hdr, TCP_URG, 1); }
+	| K_ACK { proto_field_set_be16(hdr, TCP_ACK, 1); }
+	| K_PSH { proto_field_set_be16(hdr, TCP_PSH, 1); }
+	| K_RST { proto_field_set_be16(hdr, TCP_RST, 1); }
+	| K_SYN { proto_field_set_be16(hdr, TCP_SYN, 1); }
+	| K_FIN { proto_field_set_be16(hdr, TCP_FIN, 1); }
+	| K_WINDOW skip_white '=' skip_white number
+		{ proto_field_set_be16(hdr, TCP_WINDOW, $5); }
+	| K_CSUM skip_white '=' skip_white number
+		{ proto_field_set_be16(hdr, TCP_CSUM, $5); }
+	| K_URG_PTR skip_white '=' skip_white number
+		{ proto_field_set_be16(hdr, TCP_URG_PTR, $5); }
+	;
+
+tcp
+	: K_TCP	{ proto_add(PROTO_TCP); }
+	;
+
 %%
 
 static void finalize_packet(void)