tap: Split tap_ip6_send() into UDP and ICMP variants

tap_ip6_send() has special case logic to compute the checksums for UDP
and ICMP packets, which is a mild layering violation.  By using a suitable
helper we can split it into tap_udp6_send() and tap_icmp6_send() functions
without greatly increasing the code size, this removing that layering
violation.

We make some small changes to the interface while there.  In both cases
we make the destination IPv6 address a parameter, which will be useful
later.  For the UDP variant we make it take just the UDP payload, and it
will generate the UDP header.  For the ICMP variant we pass in the ICMP
header as before.  The inconsistency is because that's what seems to be
the more natural way to invoke the function in the callers in each case.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/tap.h b/tap.h
index 011ba8e..d43c7a0 100644
--- a/tap.h
+++ b/tap.h
@@ -11,8 +11,13 @@ const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
 				     const struct in6_addr *src);
 void tap_ip4_send(const struct ctx *c, in_addr_t src, uint8_t proto,
 		  const char *in, size_t len);
-void tap_ip6_send(const struct ctx *c, const struct in6_addr *src,
-		  uint8_t proto, const char *in, size_t len, uint32_t flow);
+void tap_udp6_send(const struct ctx *c,
+		   const struct in6_addr *src, in_port_t sport,
+		   const struct in6_addr *dst, in_port_t dport,
+		   uint32_t flow, const void *in, size_t len);
+void tap_icmp6_send(const struct ctx *c,
+		    const struct in6_addr *src, const struct in6_addr *dst,
+		    void *in, size_t len);
 int tap_send(const struct ctx *c, const void *data, size_t len);
 void tap_handler(struct ctx *c, int fd, uint32_t events,
 		 const struct timespec *now);