When communicating with remote hosts on the local network, some guest
applications want to see the real MAC address of that host instead
of PASST/PASTA's own tap address. The flow_common structure is a
convenient location for storing that address, so we do that in this
commit.
Note that we don´t add actual usage of this address here, that will
be done in later commits.
Signed-off-by: Jon Maloy
---
v3: - Moved the remote host macaddress from struct flowside to
struct flow_common. I chose to call it 'omac' as suggested
by David, although in my understanding the correct name would be
'emac'. (In general I find the address naming scheme confusing.)
- Adapted to new signature of function nl_mac_get(), now passing
it the index of the template interface.
v4: - Renamed flow_commeon->omac to flow_common->tap_omac to make is
role in the code clearer
v5: - Modified the criteria for ARP/NDP table lookup like in the
previous commits.
- Removed the PIF_TAP lookup case, as David suggested, and did
instead give the flow->tap_omac field a value marking it as
non-initialized.
- Calling the cache table instead of netlink for ARP/NDP lookup.
- Unconditionally using the potentially translated IP address
in the lookup, instead of only if NAT really was applied.
v6: - Using MAC_ZERO instead of own definitions
v12:- Using MAC_UNDEF (==ff:ff:ff:ff:ff:ff) instead of MAC_ZERO,
which is a legal MAC address.
v13: - Removed call to nat_outbound() before MAC resolution, as
we are now handling guest-side visible addresses only.
- Using tgt->oaddr instead of ini->eaddr as lookup key
for fwd_neigh_mac_get(), for the same reason as above.
---
flow.c | 2 ++
flow.h | 2 ++
util.h | 2 ++
3 files changed, 6 insertions(+)
diff --git a/flow.c b/flow.c
index feefda3..a57d7b9 100644
--- a/flow.c
+++ b/flow.c
@@ -449,6 +449,7 @@ struct flowside *flow_target(const struct ctx *c, union flow *flow,
switch (f->pif[INISIDE]) {
case PIF_TAP:
+ memcpy(f->tap_omac, MAC_UNDEF, ETH_ALEN);
tgtpif = fwd_nat_from_tap(c, proto, ini, tgt);
break;
@@ -458,6 +459,7 @@ struct flowside *flow_target(const struct ctx *c, union flow *flow,
case PIF_HOST:
tgtpif = fwd_nat_from_host(c, proto, ini, tgt);
+ fwd_neigh_mac_get(c, &tgt->oaddr, f->tap_omac);
break;
default:
diff --git a/flow.h b/flow.h
index cac618a..f342895 100644
--- a/flow.h
+++ b/flow.h
@@ -177,6 +177,7 @@ int flowside_connect(const struct ctx *c, int s,
* @type: Type of packet flow
* @pif[]: Interface for each side of the flow
* @side[]: Information for each side of the flow
+ * @tap_omac: MAC address of remote endpoint as seen from the guest
*/
struct flow_common {
#ifdef __GNUC__
@@ -192,6 +193,7 @@ struct flow_common {
#endif
uint8_t pif[SIDES];
struct flowside side[SIDES];
+ uint8_t tap_omac[6];
};
#define FLOW_INDEX_BITS 17 /* 128k - 1 */
diff --git a/util.h b/util.h
index 22eaac5..6fc8f5d 100644
--- a/util.h
+++ b/util.h
@@ -101,6 +101,8 @@ void abort_with_msg(const char *fmt, ...)
((uint8_t [ETH_ALEN]){ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff })
#define MAC_ZERO ((uint8_t [ETH_ALEN]){ 0 })
#define MAC_IS_ZERO(addr) (!memcmp((addr), MAC_ZERO, ETH_ALEN))
+#define MAC_UNDEF MAC_BROADCAST
+#define MAC_IS_UNDEF(addr) (!memcmp((addr), MAC_UNDEF, ETH_ALEN))
#ifndef __bswap_constant_16
#define __bswap_constant_16(x) \
--
2.50.1