For inbound packets address to host's ::1 we rewrite the source
address to be the @nattohost address. Unless the @nattohost address
is not link local, in which case we use the host's link-local address
instead.
Confusingly we don't mirror this logic for outbound packets. We
rewrite the destination for packets bound to @nattohost into ::1, but
we don't alter packets bound for the host's link-local address. This
will probably still work in most cases, since the host's link-local
address will still go to the host, but it's a weird assymetry.
Remove the assymetry and simplify the code, by always using the
@nattohost address alone, but instead setting the @nattohost address
to the host link-local address rather than the gateway if the gateway
isn't a link-local address.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
conf.c | 8 ++++++--
tcp.c | 5 +----
udp.c | 5 +----
3 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/conf.c b/conf.c
index dd8a835..45f49eb 100644
--- a/conf.c
+++ b/conf.c
@@ -737,8 +737,12 @@ static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6,
if (MAC_IS_ZERO(mac))
nl_link(0, ifi, mac, 0, 0);
- if (gwnat && IN6_IS_ADDR_UNSPECIFIED(&ip6->nattohost))
- ip6->nattohost = ip6->router;
+ if (gwnat && IN6_IS_ADDR_UNSPECIFIED(&ip6->nattohost)) {
+ if (IN6_IS_ADDR_LINKLOCAL(&ip6->router))
+ ip6->nattohost = ip6->router;
+ else
+ ip6->nattohost = ip6->addr_ll;
+ }
if (IN6_IS_ADDR_UNSPECIFIED(&ip6->router) ||
IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ||
diff --git a/tcp.c b/tcp.c
index aa65d6e..d91e786 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2718,10 +2718,7 @@ static void tcp_snat_inbound(const struct ctx *c, union inany_addr
*addr)
if (IN6_IS_ADDR_LOOPBACK(addr6) ||
IN6_ARE_ADDR_EQUAL(addr6, &c->ip6.addr_seen) ||
IN6_ARE_ADDR_EQUAL(addr6, &c->ip6.addr)) {
- if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.nattohost))
- *addr6 = c->ip6.nattohost;
- else
- *addr6 = c->ip6.addr_ll;
+ *addr6 = c->ip6.nattohost;
}
}
}
diff --git a/udp.c b/udp.c
index 6234a8d..6cd2813 100644
--- a/udp.c
+++ b/udp.c
@@ -662,10 +662,7 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t
dstport,
bitmap_set(udp_act[V6][UDP_ACT_TAP], src_port);
- if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.nattohost))
- src = &c->ip6.nattohost;
- else
- src = &c->ip6.addr_ll;
+ src = &c->ip6.nattohost;
}
b->ip6h.saddr = *src;
--
2.40.1