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sd-dhcp-server: fix address availability checks

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The checks for finding a new available address in the pool were broken in two
ways: not using UINT32_TO_PTR() on hashmap lookups resulted in false negatives,
and the check wasn't skipping the server address if that was part of the pool.

Move the check for available addresses to a small helper function and fix both
issues, and also add a check to the REQUEST code for the server address.
This commit is contained in:
Toke Høiland-Jørgensen
2021-10-29 15:29:05 +02:00
parent d635a7f9e4
commit cb3c06a02e
1 changed files with 16 additions and 2 deletions
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src/libsystemd-network/sd-dhcp-server.c
+16 -2
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@@ -875,6 +875,17 @@ static int dhcp_server_cleanup_expired_leases(sd_dhcp_server *server) {
return 0;
}
static bool address_available(sd_dhcp_server *server, be32_t address) {
assert(server);
if (hashmap_contains(server->bound_leases_by_address, UINT32_TO_PTR(address)) ||
hashmap_contains(server->static_leases_by_address, UINT32_TO_PTR(address)) ||
address == server->address)
return false;
return true;
}
#define HASH_KEY SD_ID128_MAKE(0d,1d,fe,bd,f1,24,bd,b3,47,f1,dd,6e,73,21,93,30)
int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, size_t length) {
@@ -943,8 +954,7 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, siz
be32_t tmp_address;
tmp_address = server->subnet | htobe32(server->pool_offset + (hash + i) % server->pool_size);
if (!hashmap_contains(server->bound_leases_by_address, &tmp_address) &&
!hashmap_contains(server->static_leases_by_address, &tmp_address)) {
if (address_available(server, tmp_address)) {
address = tmp_address;
break;
}
@@ -1021,6 +1031,10 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, siz
address = req->message->ciaddr;
}
/* disallow our own address */
if (address == server->address)
return 0;
pool_offset = get_pool_offset(server, address);
existing_lease_by_address = hashmap_get(server->bound_leases_by_address, UINT32_TO_PTR(address));