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.
---
flow.c | 21 ++++++++++++++++++++-
flow.h | 2 ++
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/flow.c b/flow.c
index da5c813..dcda1a7 100644
--- a/flow.c
+++ b/flow.c
@@ -20,6 +20,7 @@
#include "flow.h"
#include "flow_table.h"
#include "repair.h"
+#include "netlink.h"
const char *flow_state_str[] = {
[FLOW_STATE_FREE] = "FREE",
@@ -438,18 +439,28 @@ struct flowside *flow_target(const struct ctx *c, union flow *flow,
{
char estr[INANY_ADDRSTRLEN], fstr[INANY_ADDRSTRLEN];
struct flow_common *f = &flow->f;
- const struct flowside *ini = &f->side[INISIDE];
+ struct flowside *ini = &f->side[INISIDE];
struct flowside *tgt = &f->side[TGTSIDE];
uint8_t tgtpif = PIF_NONE;
+ int ifi;
ASSERT(flow_new_entry == flow && f->state == FLOW_STATE_INI);
ASSERT(f->type == FLOW_TYPE_NONE);
ASSERT(f->pif[INISIDE] != PIF_NONE && f->pif[TGTSIDE] == PIF_NONE);
ASSERT(flow->f.state == FLOW_STATE_INI);
+ memcpy(f->omac, c->our_tap_mac, ETH_ALEN);
switch (f->pif[INISIDE]) {
case PIF_TAP:
tgtpif = fwd_nat_from_tap(c, proto, ini, tgt);
+
+ /* If there was no NAT, chances are this is a remote host
+ * on the template interface's local network segment.
+ * If so, insert its MAC address
+ */
+ ifi = inany_v4(&ini->oaddr) ? c->ifi4 : c->ifi6;
+ if (inany_equals(&ini->oaddr, &tgt->eaddr))
+ nl_mac_get(nl_sock, &ini->oaddr, ifi, f->omac);
break;
case PIF_SPLICE:
@@ -458,6 +469,14 @@ struct flowside *flow_target(const struct ctx *c, union flow *flow,
case PIF_HOST:
tgtpif = fwd_nat_from_host(c, proto, ini, tgt);
+
+ /* If there was no NAT, chances are this is a remote host
+ * on the template interface's local network segment.
+ * If so, insert its MAC address
+ */
+ ifi = inany_v4(&ini->eaddr) ? c->ifi4 : c->ifi6;
+ if (inany_equals(&ini->eaddr, &tgt->oaddr))
+ nl_mac_get(nl_sock, &ini->eaddr, ifi, f->omac);
break;
default:
diff --git a/flow.h b/flow.h
index cac618a..3240fb7 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
+ * @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];
+ unsigned char omac[6];
};
#define FLOW_INDEX_BITS 17 /* 128k - 1 */
--
2.48.1