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rose: keep the route needed for routing loop detection #4

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Merged
kuba-moo merged 1 commit into from
Sep 11, 2026
Merged

rose: keep the route needed for routing loop detection #4

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71 changes: 56 additions & 15 deletions net/rose/rose_route.c
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Original file line number Diff line number Diff line change
Expand Up @@ -851,6 +851,21 @@ void rose_link_device_down(struct net_device *dev)
}
}

/*
* Is this Call Request the very same call as the one an existing route
* was built for? Both the loop detection and the reuse of a stale LCI
* below rely on this test.
*/
static bool rose_same_call(const struct rose_route *rose_route,
const rose_address *src_addr,
const struct rose_facilities_struct *facilities)
{
return rose_route->rand == facilities->rand &&
rosecmp(src_addr, &rose_route->src_addr) == 0 &&
ax25cmp(&facilities->dest_call, &rose_route->src_call) == 0 &&
ax25cmp(&facilities->source_call, &rose_route->dest_call) == 0;
}

/*
* Route a frame to an appropriate AX.25 connection.
* A NULL ax25_cb indicates an internally generated frame.
Expand Down Expand Up @@ -961,6 +976,16 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
goto out;
}

memset(&facilities, 0x00, sizeof(struct rose_facilities_struct));

if (frametype == ROSE_CALL_REQUEST &&
!rose_parse_facilities(skb->data + ROSE_CALL_REQ_FACILITIES_OFF,
skb->len - ROSE_CALL_REQ_FACILITIES_OFF,
&facilities)) {
rose_transmit_clear_request(rose_neigh, lci, ROSE_INVALID_FACILITY, 76);
goto out;
}

/*
* Route it to the next in line if we have an entry for it.
*/
Expand All @@ -969,7 +994,21 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
if (rose_route->lci1 == lci &&
rose_route->neigh1 == rose_neigh) {
if (frametype == ROSE_CALL_REQUEST) {
/* F6FBB - Remove an existing unused route */
if (rose_same_call(rose_route, src_addr,
&facilities)) {
/*
* The very same call coming back
* to us: a routing loop. Keep
* the route, the loop detection
* below is what matches on it.
*/
rose_transmit_clear_request(rose_neigh,
lci,
ROSE_NOT_OBTAINABLE,
120);
goto out;
}
/* Remove an existing unused route */
rose_remove_route(rose_route);
break;
} else if (rose_route->neigh2 != NULL) {
Expand All @@ -990,7 +1029,21 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
if (rose_route->lci2 == lci &&
rose_route->neigh2 == rose_neigh) {
if (frametype == ROSE_CALL_REQUEST) {
/* F6FBB - Remove an existing unused route */
if (rose_same_call(rose_route, src_addr,
&facilities)) {
/*
* The very same call coming back
* to us: a routing loop. Keep
* the route, the loop detection
* below is what matches on it.
*/
rose_transmit_clear_request(rose_neigh,
lci,
ROSE_NOT_OBTAINABLE,
120);
goto out;
}
/* Remove an existing unused route */
rose_remove_route(rose_route);
break;
} else if (rose_route->neigh1 != NULL) {
Expand Down Expand Up @@ -1021,24 +1074,12 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
goto out;
}

memset(&facilities, 0x00, sizeof(struct rose_facilities_struct));

if (!rose_parse_facilities(skb->data + ROSE_CALL_REQ_FACILITIES_OFF,
skb->len - ROSE_CALL_REQ_FACILITIES_OFF,
&facilities)) {
rose_transmit_clear_request(rose_neigh, lci, ROSE_INVALID_FACILITY, 76);
goto out;
}

/*
* Check for routing loops.
*/
rose_route = rose_route_list;
while (rose_route != NULL) {
if (rose_route->rand == facilities.rand &&
rosecmp(src_addr, &rose_route->src_addr) == 0 &&
ax25cmp(&facilities.dest_call, &rose_route->src_call) == 0 &&
ax25cmp(&facilities.source_call, &rose_route->dest_call) == 0) {
if (rose_same_call(rose_route, src_addr, &facilities)) {
rose_transmit_clear_request(rose_neigh, lci, ROSE_NOT_OBTAINABLE, 120);
goto out;
}
Expand Down