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More of the fix for bug #7118 - nmbd problems with socket address.

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Add a simple "processed packet queue" cache to stop nmbd responding to
packets received on the broadcast and non-broadcast socket (which
it has opened when "nmbd bind explicit broadcast = yes").

This is a very simple packet queue - it only keeps the packets
processed during a single call to listen_for_packets() (i.e. one
select call). This means that if the delivery notification for a
packet received on both broadcast and non-broadcast addresses
is done in two different select calls, the packet will still be
processed twice. This is a very rare occurrance and we can just
live with it when it does as the protocol is stateless. If this
is ever flagged as a repeatable problem then we can add a longer
lived cache, using timeout processing to clear etc. etc. But without
storing all packets processed we can never be *sure* we've eliminated
the race condition so I'm going to go with this simple solution until
someone proves a more complex one is needed :-).

Jeremy.
This commit is contained in:
Jeremy Allison 2010-02-10 12:32:05 -08:00
parent 84fba3c1bc
commit c2f3ed48c5
1 changed files with 89 additions and 0 deletions
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89
source3/nmbd/nmbd_packets.c
View File

@ -1764,6 +1764,83 @@ only use %d.\n", count, FD_SETSIZE));
return False;
}
/****************************************************************************
List of packets we're processing this select.
***************************************************************************/
struct processed_packet {
struct processed_packet *next;
struct processed_packet *prev;
enum packet_type packet_type;
struct in_addr ip;
int packet_id;
};
/****************************************************************************
Have we seen this before ?
***************************************************************************/
static bool is_processed_packet(struct processed_packet *processed_packet_list,
struct packet_struct *packet)
{
struct processed_packet *p = NULL;
for (p = processed_packet_list; p; p = p->next) {
if (ip_equal_v4(p->ip, packet->ip) && p->packet_type == packet->packet_type) {
if ((p->packet_type == NMB_PACKET) &&
(p->packet_id ==
packet->packet.nmb.header.name_trn_id)) {
return true;
} else if ((p->packet_type == DGRAM_PACKET) &&
(p->packet_id ==
packet->packet.dgram.header.dgm_id)) {
return true;
}
}
}
return false;
}
/****************************************************************************
Keep a list of what we've seen before.
***************************************************************************/
static bool store_processed_packet(struct processed_packet **pp_processed_packet_list,
struct packet_struct *packet)
{
struct processed_packet *p = SMB_MALLOC_P(struct processed_packet);
if (!p) {
return false;
}
p->packet_type = packet->packet_type;
p->ip = packet->ip;
if (packet->packet_type == NMB_PACKET) {
p->packet_id = packet->packet.nmb.header.name_trn_id;
} else if (packet->packet_type == DGRAM_PACKET) {
p->packet_id = packet->packet.dgram.header.dgm_id;
} else {
return false;
}
DLIST_ADD(*pp_processed_packet_list, p);
return true;
}
/****************************************************************************
Throw away what we've seen before.
***************************************************************************/
static void free_processed_packet_list(struct processed_packet **pp_processed_packet_list)
{
struct processed_packet *p = NULL, *next = NULL;
for (p = *pp_processed_packet_list; p; p = next) {
next = p->next;
DLIST_REMOVE(*pp_processed_packet_list, p);
SAFE_FREE(p);
}
}
/****************************************************************************
Listens for NMB or DGRAM packets, and queues them.
return True if the socket is dead
@ -1784,6 +1861,7 @@ bool listen_for_packets(bool run_election)
#ifndef SYNC_DNS
int dns_fd;
#endif
struct processed_packet *processed_packet_list = NULL;
if(listen_set == NULL || rescan_listen_set) {
if(create_listen_fdset(&listen_set, &sock_array, &listen_number, &maxfd)) {
@ -1906,6 +1984,16 @@ bool listen_for_packets(bool run_election)
}
}
if (is_processed_packet(processed_packet_list, packet)) {
DEBUG(7,("discarding duplicate packet from %s:%d\n",
inet_ntoa(packet->ip),packet->port));
free_packet(packet);
continue;
}
store_processed_packet(&processed_packet_list, packet);
/*
* 0,2,4,... are unicast sockets
* 1,3,5,... are broadcast sockets
@ -1926,6 +2014,7 @@ bool listen_for_packets(bool run_election)
queue_packet(packet);
}
free_processed_packet_list(&processed_packet_list);
return False;
}