Use typing to reduce chances of IPv4 endianness errors

We recently corrected some errors handling the endianness of IPv4
addresses.  These are very easy errors to make since although we mostly
store them in network endianness, we sometimes need to manipulate them in
host endianness.

To reduce the chances of making such mistakes again, change to always using
a (struct in_addr) instead of a bare in_addr_t or uint32_t to store network
endian addresses.  This makes it harder to accidentally do arithmetic or
comparisons on such addresses as if they were host endian.

We introduce a number of IN4_IS_ADDR_*() helpers to make it easier to
directly work with struct in_addr values.  This has the additional benefit
of making the IPv4 and IPv6 paths more visually similar.

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

1 files changed, 4 insertions, 4 deletions

diff --git a/tap.h b/tap.h
index 743bc58..674ab5c 100644
--- a/tap.h
+++ b/tap.h
@@ -6,11 +6,11 @@
 #ifndef TAP_H
 #define TAP_H
 
-in_addr_t tap_ip4_daddr(const struct ctx *c);
-void tap_udp4_send(const struct ctx *c, in_addr_t src, in_port_t sport,
-		   in_addr_t dst, in_port_t dport,
+struct in_addr tap_ip4_daddr(const struct ctx *c);
+void tap_udp4_send(const struct ctx *c, struct in_addr src, in_port_t sport,
+		   struct in_addr dst, in_port_t dport,
 		   const void *in, size_t len);
-void tap_icmp4_send(const struct ctx *c, in_addr_t src, in_addr_t dst,
+void tap_icmp4_send(const struct ctx *c, struct in_addr src, struct in_addr dst,
 		    void *in, size_t len);
 const struct in6_addr *tap_ip6_daddr(const struct ctx *c,
 				     const struct in6_addr *src);