trafgen: Add checksum helpers for TCP/UDP over IPv6

Add the csumudp6 and csumtcp6 helper functions in order to simplify
checksum generation for TCP/UDP packets sent over IPv6.

trafgen example for TCP over IPv6:

{
  /* MAC Destination */
  fill(0xff, 6),
  /* MAC Source */
  0x00, 0x02, 0xb3, drnd(3),
  /* IPv6 Protocol */
  c16(0x86DD),
  /* Version, Traffic Class, Flow Label */
  0b01100000, c8(0), c16(0),
  /* Payload Length */
  c16(54),
  /* Next Header (TCP) */
  c8(6),
  /* Hop Limit */
  c8(64),
  /* Source IPv6 */
  0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0xba, 0xac, 0x6f, 0xff, 0xfe, 0xa4, 0x12, 0xe3,
  /* Destination IPv6 */
  0xfe, 0x80, 0x82, 0x2e, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0xde, 0xff, 0xfe, 0x00, 0x06, 0xde,
  /* TCP Source Port */
  c16(55042),
  /* TCP Destination Port */
  c16(55043),
  /* TCP Sequence Number */
  drnd(4),
  /* TCP Ackn. Number */
  c32(0),
  /* TCP Header length + TCP SYN/ECN Flag */
  c16((8 << 12) | (1 << 1) | (1 << 6))
  /* Window Size */
  c16(16),
  /* TCP Checksum (offset IPv6, offset TCP) */
  csumtcp6(14, 54),
  /* TCP Options */
  0x00, 0x00, 0x01, 0x01, 0x08, 0x0a, 0x06,
  0x91, 0x68, 0x7d, 0x06, 0x91, 0x68, 0x6f,
  /* Data blob */
  "foobar!",
}

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

7 files changed, 71 insertions, 6 deletions

diff --git a/csum.h b/csum.h
index ab549f8..19a8bc5 100644
--- a/csum.h
+++ b/csum.h
@@ -3,6 +3,7 @@
 
 #include <netinet/in.h>
 #include <netinet/ip.h>
+#include <netinet/ip6.h>
 
 #include "built_in.h"
 
@@ -171,4 +172,31 @@ static inline uint16_t p4_csum(const struct ip *ip, const uint8_t *data,
 	return __in_cksum(vec, 2);
 }
 
+static inline uint16_t p6_csum(const struct ip6_hdr *ip6, const uint8_t *data,
+			       uint32_t len, uint8_t next_proto)
+{
+	struct cksum_vec vec[2];
+	struct pseudo_hdr {
+		uint8_t src[16];
+		uint8_t dst[16];
+		uint32_t len;
+		uint8_t mbz[3];
+		uint8_t proto;
+	} __packed ph;
+
+	memcpy(&ph.src, ip6->ip6_src.s6_addr, sizeof(ph.src));
+	memcpy(&ph.dst, ip6->ip6_dst.s6_addr, sizeof(ph.dst));
+	ph.len = htons(len);
+	memset(&ph.mbz, 0, sizeof(ph.mbz));
+	ph.proto = next_proto;
+
+	vec[0].ptr = (const uint8_t *) (void *) &ph;
+	vec[0].len = sizeof(ph);
+
+	vec[1].ptr = data;
+	vec[1].len = len;
+
+	return __in_cksum(vec, 2);
+}
+
 #endif /* CSUM_H */
diff --git a/trafgen.8 b/trafgen.8
index 31c2f52..84ef518 100644
--- a/trafgen.8
+++ b/trafgen.8
@@ -247,6 +247,8 @@ ii) Checksum helper functions (packet offsets start with 0):
    IP/ICMP checksum:        csumip/csumicmp(<off-from>, <off-to>)
    UDP checksum:            csumudp(<off-iphdr>, <off-udpdr>)
    TCP checksum:            csumtcp(<off-iphdr>, <off-tcphdr>)
+   UDP checksum (IPv6):     csumudp6(<off-ip6hdr>, <off-udpdr>)
+   TCP checksum (IPv6):     csumtcp6(<off-ip6hdr>, <off-tcphdr>)
 .PP
 iii) Multibyte functions, compile-time expression evaluation:
 .PP
diff --git a/trafgen.c b/trafgen.c
index 93bb1b4..71e4f3a 100644
--- a/trafgen.c
+++ b/trafgen.c
@@ -345,6 +345,18 @@ static void apply_csum16(int id)
 				      (packets[id].len - csum->to),
 				      IPPROTO_TCP);
 			break;
+		case CSUM_UDP6:
+			sum = p6_csum((void *) packets[id].payload + csum->from,
+				      packets[id].payload + csum->to,
+				      (packets[id].len - csum->to),
+				      IPPROTO_UDP);
+			break;
+		case CSUM_TCP6:
+			sum = p6_csum((void *) packets[id].payload + csum->from,
+				      packets[id].payload + csum->to,
+				      (packets[id].len - csum->to),
+				      IPPROTO_TCP);
+			break;
 		default:
 			bug();
 			break;
diff --git a/trafgen_conf.h b/trafgen_conf.h
index f92e14c..3922d15 100644
--- a/trafgen_conf.h
+++ b/trafgen_conf.h
@@ -12,6 +12,8 @@ enum csum {
 	CSUM_IP,
 	CSUM_UDP,
 	CSUM_TCP,
+	CSUM_UDP6,
+	CSUM_TCP6,
 };
 
 struct counter {
diff --git a/trafgen_lexer.l b/trafgen_lexer.l
index a361bfc..6c27b0c 100644
--- a/trafgen_lexer.l
+++ b/trafgen_lexer.l
@@ -87,6 +87,8 @@ number_ascii	([a-zA-Z])
 "csumicmp4"	{ return K_CSUMIP; }
 "csumudp"	{ return K_CSUMUDP; }
 "csumtcp"	{ return K_CSUMTCP; }
+"csumudp6"	{ return K_CSUMUDP6; }
+"csumtcp6"	{ return K_CSUMTCP6; }
 "drnd"		{ return K_DRND; }
 "dinc"		{ return K_DINC; }
 "ddec"		{ return K_DDEC; }
diff --git a/trafgen_parser.y b/trafgen_parser.y
index df234f4..f934baa 100644
--- a/trafgen_parser.y
+++ b/trafgen_parser.y
@@ -200,9 +200,21 @@ static void __set_csum16_static(size_t from, size_t to, enum csum which __maybe_
 	set_byte(psum[1]);
 }
 
+static inline bool is_dynamic_csum(enum csum which)
+{
+	switch (which) {
+	case CSUM_UDP:
+	case CSUM_TCP:
+	case CSUM_UDP6:
+	case CSUM_TCP6:
+		return true;
+	default:
+		return false;
+	}
+}
+
 static void set_csum16(size_t from, size_t to, enum csum which)
 {
-	int make_it_dynamic = 0;
 	struct packet *pkt = &packets[packet_last];
 	struct packet_dyn *pktd = &packet_dyn[packetd_last];
 
@@ -218,10 +230,7 @@ static void set_csum16(size_t from, size_t to, enum csum which)
 
 	bug_on(!(from < to));
 
-	if (to >= pkt->len || which == CSUM_TCP || which == CSUM_UDP)
-		make_it_dynamic = 1;
-
-	if (has_dynamic_elems(pktd) || make_it_dynamic)
+	if (has_dynamic_elems(pktd) || to >= pkt->len || is_dynamic_csum(which))
 		__set_csum16_dynamic(from, to, which);
 	else
 		__set_csum16_static(from, to, which);
@@ -320,7 +329,7 @@ static void set_dynamic_incdec(uint8_t start, uint8_t stop, uint8_t stepping,
 }
 
 %token K_COMMENT K_FILL K_RND K_SEQINC K_SEQDEC K_DRND K_DINC K_DDEC K_WHITE
-%token K_CPU K_CSUMIP K_CSUMUDP K_CSUMTCP K_CONST8 K_CONST16 K_CONST32 K_CONST64
+%token K_CPU K_CSUMIP K_CSUMUDP K_CSUMTCP K_CSUMUDP6 K_CSUMTCP6 K_CONST8 K_CONST16 K_CONST32 K_CONST64
 
 %token ',' '{' '}' '(' ')' '[' ']' ':' '-' '+' '*' '/' '%' '&' '|' '<' '>' '^'
 
@@ -479,6 +488,10 @@ csum
 		{ set_csum16($3, $5, CSUM_TCP); }
 	| K_CSUMUDP '(' number delimiter number ')'
 		{ set_csum16($3, $5, CSUM_UDP); }
+	| K_CSUMTCP6 '(' number delimiter number ')'
+		{ set_csum16($3, $5, CSUM_TCP6); }
+	| K_CSUMUDP6 '(' number delimiter number ')'
+		{ set_csum16($3, $5, CSUM_UDP6); }
 	;
 
 seqinc
diff --git a/trafgen_stddef.h b/trafgen_stddef.h
index 13688a6..a02c817 100644
--- a/trafgen_stddef.h
+++ b/trafgen_stddef.h
@@ -120,6 +120,12 @@
 #define IP_ID_RAND		drnd(2)
 #define IP_CSUM_DEFAULT		csumip(IP_HDR_OFF_DEFAULT, 33)	/* IP-hdr offset from, to */
 
+#define IPV6_ALEN		16
+#define IPV6_VERSION		6
+#define IPV6_HDR_OFF_DEFAULT	14
+#define IPV6_SRC_RAND		drnd(IPV6_ALEN)
+#define IPV6_DST_RAND		drnd(IPV6_ALEN)
+
 #define ICMP_ECHOREPLY		0	/* Echo Reply */
 #define ICMP_DEST_UNREACH	3	/* Destination Unreachable */
 #define ICMP_SOURCE_QUENCH	4	/* Source Quench */