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netif_add: ensure netif->num is unique even if more than 255 netifs have been added/removed since system startup (e.g. by ppp)

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This commit is contained in:
goldsimon 2017-02-23 20:41:54 +01:00
parent 76763c9bcd
commit 01cc06bcb8
1 changed files with 23 additions and 5 deletions
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28
src/core/netif.c
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@ -250,6 +250,8 @@ netif_add(struct netif *netif,
#endif /* LWIP_IPV4 */
void *state, netif_init_fn init, netif_input_fn input)
{
struct netif *netif2;
int num_netifs;
#if LWIP_IPV6
s8_t i;
#endif
@ -304,7 +306,7 @@ netif_add(struct netif *netif,
/* remember netif specific state information data */
netif->state = state;
netif->num = netif_num++;
netif->num = netif_num;
netif->input = input;
NETIF_SET_HWADDRHINT(netif, NULL);
@ -321,10 +323,26 @@ netif_add(struct netif *netif,
return NULL;
}
/* check that netif_num has not overflowed or that init callback
provided a valid number (we don't support 255 since that can't be
converted to an index) */
LWIP_ASSERT("Netif num overflow/invalid num", netif->num < 255);
/* Assign a unique netif number in the range [0..254], so that (num+1) can
serve as an interface index that fits in a u8_t.
We assume that the new netif has not yet been added to the list here.
This algorithm is O(n^2), but that should be OK for lwIP.
*/
do {
if (netif->num == 255) {
netif->num = 0;
}
num_netifs = 0;
for (netif2 = netif_list; netif2 != NULL; netif2 = netif2->next) {
num_netifs++;
LWIP_ASSERT("too many netifs, max. supported number is 255", num_netifs <= 255);
if (netif2->num == netif->num) {
netif->num++;
break;
}
}
} while (netif2 != NULL);
netif_num = netif->num + 1;
/* add this netif to the list */
netif->next = netif_list;