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>

1 files changed, 28 insertions, 0 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 */