patch-2.4.20 linux-2.4.20/net/ipv4/netfilter/ip_conntrack_core.c

• Lines: 728
• Date: Thu Nov 28 15:53:15 2002
• Orig file: linux-2.4.19/net/ipv4/netfilter/ip_conntrack_core.c
• Orig date: Fri Aug 2 17:39:46 2002

diff -urN linux-2.4.19/net/ipv4/netfilter/ip_conntrack_core.c linux-2.4.20/net/ipv4/netfilter/ip_conntrack_core.c
@@ -3,7 +3,15 @@
    extension. */
 
 /* (c) 1999 Paul `Rusty' Russell.  Licenced under the GNU General
-   Public Licence. */
+ * Public Licence. 
+ *
+ * 23 Apr 2001: Harald Welte <laforge@gnumonks.org>
+ * 	- new API and handling of conntrack/nat helpers
+ * 	- now capable of multiple expectations for one master
+ * 16 Jul 2002: Harald Welte <laforge@gnumonks.org>
+ * 	- add usage/reference counts to ip_conntrack_expect
+ *	- export ip_conntrack[_expect]_{find_get,put} functions
+ * */
 
 #ifdef MODULE
 #define __NO_VERSION__
@@ -37,6 +45,8 @@
 #include <linux/netfilter_ipv4/ip_conntrack_core.h>
 #include <linux/netfilter_ipv4/listhelp.h>
 
+#define IP_CONNTRACK_VERSION	"2.1"
+
 #if 0
 #define DEBUGP printk
 #else
@@ -44,9 +54,10 @@
 #endif
 
 DECLARE_RWLOCK(ip_conntrack_lock);
+DECLARE_RWLOCK(ip_conntrack_expect_tuple_lock);
 
 void (*ip_conntrack_destroyed)(struct ip_conntrack *conntrack) = NULL;
-LIST_HEAD(expect_list);
+LIST_HEAD(ip_conntrack_expect_list);
 LIST_HEAD(protocol_list);
 static LIST_HEAD(helpers);
 unsigned int ip_conntrack_htable_size = 0;
@@ -63,7 +74,7 @@
 	return protocol == curr->proto;
 }
 
-struct ip_conntrack_protocol *__find_proto(u_int8_t protocol)
+struct ip_conntrack_protocol *__ip_ct_find_proto(u_int8_t protocol)
 {
 	struct ip_conntrack_protocol *p;
 
@@ -76,17 +87,18 @@
 	return p;
 }
 
-struct ip_conntrack_protocol *find_proto(u_int8_t protocol)
+struct ip_conntrack_protocol *ip_ct_find_proto(u_int8_t protocol)
 {
 	struct ip_conntrack_protocol *p;
 
 	READ_LOCK(&ip_conntrack_lock);
-	p = __find_proto(protocol);
+	p = __ip_ct_find_proto(protocol);
 	READ_UNLOCK(&ip_conntrack_lock);
 	return p;
 }
 
-static inline void ip_conntrack_put(struct ip_conntrack *ct)
+inline void 
+ip_conntrack_put(struct ip_conntrack *ct)
 {
 	IP_NF_ASSERT(ct);
 	IP_NF_ASSERT(ct->infos[0].master);
@@ -150,9 +162,135 @@
 	return protocol->invert_tuple(inverse, orig);
 }
 
+
+/* ip_conntrack_expect helper functions */
+
+/* Compare tuple parts depending on mask. */
+static inline int expect_cmp(const struct ip_conntrack_expect *i,
+			     const struct ip_conntrack_tuple *tuple)
+{
+	MUST_BE_READ_LOCKED(&ip_conntrack_expect_tuple_lock);
+	return ip_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask);
+}
+
+static void
+destroy_expect(struct ip_conntrack_expect *exp)
+{
+	DEBUGP("destroy_expect(%p) use=%d\n", exp, atomic_read(exp->use));
+	IP_NF_ASSERT(atomic_read(exp->use));
+	IP_NF_ASSERT(!timer_pending(&exp->timeout));
+
+	kfree(exp);
+}
+
+
+inline void ip_conntrack_expect_put(struct ip_conntrack_expect *exp)
+{
+	IP_NF_ASSERT(exp);
+
+	if (atomic_dec_and_test(&exp->use)) {
+		/* usage count dropped to zero */
+		destroy_expect(exp);
+	}
+}
+
+static inline struct ip_conntrack_expect *
+__ip_ct_expect_find(const struct ip_conntrack_tuple *tuple)
+{
+	MUST_BE_READ_LOCKED(&ip_conntrack_lock);
+	MUST_BE_READ_LOCKED(&ip_conntrack_expect_tuple_lock);
+	return LIST_FIND(&ip_conntrack_expect_list, expect_cmp, 
+			 struct ip_conntrack_expect *, tuple);
+}
+
+/* Find a expectation corresponding to a tuple. */
+struct ip_conntrack_expect *
+ip_conntrack_expect_find_get(const struct ip_conntrack_tuple *tuple)
+{
+	struct ip_conntrack_expect *exp;
+
+	READ_LOCK(&ip_conntrack_lock);
+	READ_LOCK(&ip_conntrack_expect_tuple_lock);
+	exp = __ip_ct_expect_find(tuple);
+	if (exp)
+		atomic_inc(&exp->use);
+	READ_UNLOCK(&ip_conntrack_expect_tuple_lock);
+	READ_UNLOCK(&ip_conntrack_lock);
+
+	return exp;
+}
+
+/* remove one specific expectation from all lists and drop refcount,
+ * does _NOT_ delete the timer. */
+static void __unexpect_related(struct ip_conntrack_expect *expect)
+{
+	DEBUGP("unexpect_related(%p)\n", expect);
+	MUST_BE_WRITE_LOCKED(&ip_conntrack_lock);
+
+	/* we're not allowed to unexpect a confirmed expectation! */
+	IP_NF_ASSERT(!expect->sibling);
+
+	/* delete from global and local lists */
+	list_del(&expect->list);
+	list_del(&expect->expected_list);
+
+	/* decrement expect-count of master conntrack */
+	if (expect->expectant)
+		expect->expectant->expecting--;
+
+	ip_conntrack_expect_put(expect);
+}
+
+/* remove one specific expecatation from all lists, drop refcount
+ * and expire timer. 
+ * This function can _NOT_ be called for confirmed expects! */
+static void unexpect_related(struct ip_conntrack_expect *expect)
+{
+	IP_NF_ASSERT(expect->expectant);
+	IP_NF_ASSERT(expect->expectant->helper);
+	/* if we are supposed to have a timer, but we can't delete
+	 * it: race condition.  __unexpect_related will
+	 * be calledd by timeout function */
+	if (expect->expectant->helper->timeout
+	    && !del_timer(&expect->timeout))
+		return;
+
+	__unexpect_related(expect);
+}
+
+/* delete all unconfirmed expectations for this conntrack */
+static void remove_expectations(struct ip_conntrack *ct)
+{
+	struct list_head *exp_entry, *next;
+	struct ip_conntrack_expect *exp;
+
+	DEBUGP("remove_expectations(%p)\n", ct);
+
+	for (exp_entry = ct->sibling_list.next;
+	     exp_entry != &ct->sibling_list; exp_entry = next) {
+		next = exp_entry->next;
+		exp = list_entry(exp_entry, struct ip_conntrack_expect,
+				 expected_list);
+
+		/* we skip established expectations, as we want to delete
+		 * the un-established ones only */
+		if (exp->sibling) {
+			DEBUGP("remove_expectations: skipping established %p of %p\n", exp->sibling, ct);
+			continue;
+		}
+
+		IP_NF_ASSERT(list_inlist(&ip_conntrack_expect_list, exp));
+		IP_NF_ASSERT(exp->expectant == ct);
+
+		/* delete expectation from global and private lists */
+		unexpect_related(exp);
+	}
+}
+
 static void
 clean_from_lists(struct ip_conntrack *ct)
 {
+	DEBUGP("clean_from_lists(%p)\n", ct);
 	MUST_BE_WRITE_LOCKED(&ip_conntrack_lock);
 	/* Remove from both hash lists: must not NULL out next ptrs,
            otherwise we'll look unconfirmed.  Fortunately, LIST_DELETE
@@ -163,12 +301,9 @@
 	LIST_DELETE(&ip_conntrack_hash
 		    [hash_conntrack(&ct->tuplehash[IP_CT_DIR_REPLY].tuple)],
 		    &ct->tuplehash[IP_CT_DIR_REPLY]);
-	/* If our expected is in the list, take it out. */
-	if (ct->expected.expectant) {
-		IP_NF_ASSERT(list_inlist(&expect_list, &ct->expected));
-		IP_NF_ASSERT(ct->expected.expectant == ct);
-		LIST_DELETE(&expect_list, &ct->expected);
-	}
+
+	/* Destroy all un-established, pending expectations */
+	remove_expectations(ct);
 }
 
 static void
@@ -177,21 +312,34 @@
 	struct ip_conntrack *ct = (struct ip_conntrack *)nfct;
 	struct ip_conntrack_protocol *proto;
 
+	DEBUGP("destroy_conntrack(%p)\n", ct);
 	IP_NF_ASSERT(atomic_read(&nfct->use) == 0);
 	IP_NF_ASSERT(!timer_pending(&ct->timeout));
 
-	if (ct->master.master)
-		nf_conntrack_put(&ct->master);
+	if (ct->master && master_ct(ct))
+		ip_conntrack_put(master_ct(ct));
 
 	/* To make sure we don't get any weird locking issues here:
 	 * destroy_conntrack() MUST NOT be called with a write lock
 	 * to ip_conntrack_lock!!! -HW */
-	proto = find_proto(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
+	proto = ip_ct_find_proto(ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.protonum);
 	if (proto && proto->destroy)
 		proto->destroy(ct);
 
 	if (ip_conntrack_destroyed)
 		ip_conntrack_destroyed(ct);
+
+	WRITE_LOCK(&ip_conntrack_lock);
+	/* Delete our master expectation */
+	if (ct->master) {
+		/* can't call __unexpect_related here,
+		 * since it would screw up expect_list */
+		list_del(&ct->master->expected_list);
+		kfree(ct->master);
+	}
+	WRITE_UNLOCK(&ip_conntrack_lock);
+
+	DEBUGP("destroy_conntrack: returning ct=%p to slab\n", ct);
 	kmem_cache_free(ip_conntrack_cachep, ct);
 	atomic_dec(&ip_conntrack_count);
 }
@@ -315,7 +463,7 @@
 			     &ct->tuplehash[IP_CT_DIR_REPLY]);
 		/* Timer relative to confirmation time, not original
 		   setting time, otherwise we'd get timer wrap in
-		   wierd delay cases. */
+		   weird delay cases. */
 		ct->timeout.expires += jiffies;
 		add_timer(&ct->timeout);
 		atomic_inc(&ct->ct_general.use);
@@ -389,7 +537,7 @@
 		return NULL;
 	}
 
-	innerproto = find_proto(inner->protocol);
+	innerproto = ip_ct_find_proto(inner->protocol);
 	/* Are they talking about one of our connections? */
 	if (inner->ihl * 4 + 8 > datalen
 	    || !get_tuple(inner, datalen, &origtuple, innerproto)) {
@@ -469,11 +617,11 @@
 	return ip_ct_tuple_mask_cmp(rtuple, &i->tuple, &i->mask);
 }
 
-/* Compare parts depending on mask. */
-static inline int expect_cmp(const struct ip_conntrack_expect *i,
-			     const struct ip_conntrack_tuple *tuple)
+struct ip_conntrack_helper *ip_ct_find_helper(const struct ip_conntrack_tuple *tuple)
 {
-	return ip_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask);
+	return LIST_FIND(&helpers, helper_cmp,
+			 struct ip_conntrack_helper *,
+			 tuple);
 }
 
 /* Allocate a new conntrack: we return -ENOMEM if classification
@@ -521,7 +669,7 @@
 		return ERR_PTR(-ENOMEM);
 	}
 
-	memset(conntrack, 0, sizeof(struct ip_conntrack));
+	memset(conntrack, 0, sizeof(*conntrack));
 	atomic_set(&conntrack->ct_general.use, 1);
 	conntrack->ct_general.destroy = destroy_conntrack;
 	conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *tuple;
@@ -540,31 +688,44 @@
 	conntrack->timeout.data = (unsigned long)conntrack;
 	conntrack->timeout.function = death_by_timeout;
 
+	INIT_LIST_HEAD(&conntrack->sibling_list);
+
 	/* Mark clearly that it's not in the hash table. */
 	conntrack->tuplehash[IP_CT_DIR_ORIGINAL].list.next = NULL;
 
-	/* Write lock required for deletion of expected.  Without
-           this, a read-lock would do. */
 	WRITE_LOCK(&ip_conntrack_lock);
-	conntrack->helper = LIST_FIND(&helpers, helper_cmp,
-				      struct ip_conntrack_helper *,
-				      &repl_tuple);
 	/* Need finding and deleting of expected ONLY if we win race */
-	expected = LIST_FIND(&expect_list, expect_cmp,
+	READ_LOCK(&ip_conntrack_expect_tuple_lock);
+	expected = LIST_FIND(&ip_conntrack_expect_list, expect_cmp,
 			     struct ip_conntrack_expect *, tuple);
+	READ_UNLOCK(&ip_conntrack_expect_tuple_lock);
+
+	/* Look up the conntrack helper for master connections only */
+	if (!expected)
+		conntrack->helper = ip_ct_find_helper(&repl_tuple);
+
+	/* If the expectation is dying, then this is a looser. */
+	if (expected
+	    && expected->expectant->helper->timeout
+	    && ! del_timer(&expected->timeout))
+		expected = NULL;
+
 	/* If master is not in hash table yet (ie. packet hasn't left
 	   this machine yet), how can other end know about expected?
 	   Hence these are not the droids you are looking for (if
 	   master ct never got confirmed, we'd hold a reference to it
 	   and weird things would happen to future packets). */
 	if (expected && is_confirmed(expected->expectant)) {
+		DEBUGP("conntrack: expectation arrives ct=%p exp=%p\n",
+			conntrack, expected);
 		/* Welcome, Mr. Bond.  We've been expecting you... */
+		IP_NF_ASSERT(master_ct(conntrack));
 		conntrack->status = IPS_EXPECTED;
-		conntrack->master.master = &expected->expectant->ct_general;
-		IP_NF_ASSERT(conntrack->master.master);
-		LIST_DELETE(&expect_list, expected);
-		expected->expectant = NULL;
-		nf_conntrack_get(&conntrack->master);
+		conntrack->master = expected;
+		expected->sibling = conntrack;
+		LIST_DELETE(&ip_conntrack_expect_list, expected);
+		expected->expectant->expecting--;
+		nf_conntrack_get(&master_ct(conntrack)->infos[0]);
 	}
 	atomic_inc(&ip_conntrack_count);
 	WRITE_UNLOCK(&ip_conntrack_lock);
@@ -669,7 +830,7 @@
 			return NF_STOLEN;
 	}
 
-	proto = find_proto((*pskb)->nh.iph->protocol);
+	proto = ip_ct_find_proto((*pskb)->nh.iph->protocol);
 
 	/* It may be an icmp error... */
 	if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP 
@@ -713,66 +874,229 @@
 int invert_tuplepr(struct ip_conntrack_tuple *inverse,
 		   const struct ip_conntrack_tuple *orig)
 {
-	return invert_tuple(inverse, orig, find_proto(orig->dst.protonum));
+	return invert_tuple(inverse, orig, ip_ct_find_proto(orig->dst.protonum));
 }
 
-static void unexpect_related(struct ip_conntrack *related_to)
-{
-	MUST_BE_WRITE_LOCKED(&ip_conntrack_lock);
-	list_del(&related_to->expected.list);
-	related_to->expected.expectant = NULL;
+static inline int resent_expect(const struct ip_conntrack_expect *i,
+			        const struct ip_conntrack_tuple *tuple,
+			        const struct ip_conntrack_tuple *mask)
+{
+	DEBUGP("resent_expect\n");
+	DEBUGP("   tuple:   "); DUMP_TUPLE(&i->tuple);
+	DEBUGP("ct_tuple:   "); DUMP_TUPLE(&i->ct_tuple);
+	DEBUGP("test tuple: "); DUMP_TUPLE(tuple);
+	return (((i->ct_tuple.dst.protonum == 0 && ip_ct_tuple_equal(&i->tuple, tuple))
+	         || (i->ct_tuple.dst.protonum && ip_ct_tuple_equal(&i->ct_tuple, tuple)))
+		&& ip_ct_tuple_equal(&i->mask, mask));
 }
 
 /* Would two expected things clash? */
 static inline int expect_clash(const struct ip_conntrack_expect *i,
-			       const struct ip_conntrack_expect *new)
+			       const struct ip_conntrack_tuple *tuple,
+			       const struct ip_conntrack_tuple *mask)
 {
 	/* Part covered by intersection of masks must be unequal,
            otherwise they clash */
 	struct ip_conntrack_tuple intersect_mask
-		= { { i->mask.src.ip & new->mask.src.ip,
-		      { i->mask.src.u.all & new->mask.src.u.all } },
-		    { i->mask.dst.ip & new->mask.dst.ip,
-		      { i->mask.dst.u.all & new->mask.dst.u.all },
-		      i->mask.dst.protonum & new->mask.dst.protonum } };
+		= { { i->mask.src.ip & mask->src.ip,
+		      { i->mask.src.u.all & mask->src.u.all } },
+		    { i->mask.dst.ip & mask->dst.ip,
+		      { i->mask.dst.u.all & mask->dst.u.all },
+		      i->mask.dst.protonum & mask->dst.protonum } };
+
+	return ip_ct_tuple_mask_cmp(&i->tuple, tuple, &intersect_mask);
+}
+
+inline void ip_conntrack_unexpect_related(struct ip_conntrack_expect *expect)
+{
+	WRITE_LOCK(&ip_conntrack_lock);
+	unexpect_related(expect);
+	WRITE_UNLOCK(&ip_conntrack_lock);
+}
+	
+static void expectation_timed_out(unsigned long ul_expect)
+{
+	struct ip_conntrack_expect *expect = (void *) ul_expect;
 
-	return ip_ct_tuple_mask_cmp(&i->tuple, &new->tuple, &intersect_mask);
+	DEBUGP("expectation %p timed out\n", expect);	
+	WRITE_LOCK(&ip_conntrack_lock);
+	__unexpect_related(expect);
+	WRITE_UNLOCK(&ip_conntrack_lock);
 }
 
 /* Add a related connection. */
 int ip_conntrack_expect_related(struct ip_conntrack *related_to,
-				const struct ip_conntrack_tuple *tuple,
-				const struct ip_conntrack_tuple *mask,
-				int (*expectfn)(struct ip_conntrack *))
+				struct ip_conntrack_expect *expect)
 {
+	struct ip_conntrack_expect *old, *new;
+	int ret = 0;
+
 	WRITE_LOCK(&ip_conntrack_lock);
-	if (related_to->expected.expectant)
-		unexpect_related(related_to);
+	/* Because of the write lock, no reader can walk the lists,
+	 * so there is no need to use the tuple lock too */
+
+	DEBUGP("ip_conntrack_expect_related %p\n", related_to);
+	DEBUGP("tuple: "); DUMP_TUPLE(&expect->tuple);
+	DEBUGP("mask:  "); DUMP_TUPLE(&expect->mask);
+
+	old = LIST_FIND(&ip_conntrack_expect_list, resent_expect,
+		        struct ip_conntrack_expect *, &expect->tuple, 
+			&expect->mask);
+	if (old) {
+		/* Helper private data may contain offsets but no pointers
+		   pointing into the payload - otherwise we should have to copy 
+		   the data filled out by the helper over the old one */
+		DEBUGP("expect_related: resent packet\n");
+		if (related_to->helper->timeout) {
+			if (!del_timer(&old->timeout)) {
+				/* expectation is dying. Fall through */
+				old = NULL;
+			} else {
+				old->timeout.expires = jiffies + 
+					related_to->helper->timeout * HZ;
+				add_timer(&old->timeout);
+			}
+		}
+
+		if (old) {
+			WRITE_UNLOCK(&ip_conntrack_lock);
+			return -EEXIST;
+		}
+	} else if (related_to->helper->max_expected && 
+		   related_to->expecting >= related_to->helper->max_expected) {
+		struct list_head *cur_item;
+		/* old == NULL */
+	    	if (net_ratelimit())
+		    	printk(KERN_WARNING 
+		    	       "ip_conntrack: max number of expected "
+			       "connections %i of %s reached for "
+			       "%u.%u.%u.%u->%u.%u.%u.%u%s\n",
+		    	       related_to->helper->max_expected, 
+		    	       related_to->helper->name,
+		    	       NIPQUAD(related_to->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip),
+		    	       NIPQUAD(related_to->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip),
+		    	       related_to->helper->flags & IP_CT_HELPER_F_REUSE_EXPECT ?
+		    	       ", reusing" : "");
+		if (!(related_to->helper->flags & 
+		      IP_CT_HELPER_F_REUSE_EXPECT)) {
+			WRITE_UNLOCK(&ip_conntrack_lock);
+			return -EPERM;
+		}
 
-	related_to->expected.tuple = *tuple;
-	related_to->expected.mask = *mask;
-	related_to->expected.expectfn = expectfn;
+		/* choose the the oldest expectation to evict */
+		list_for_each(cur_item, &related_to->sibling_list) { 
+			struct ip_conntrack_expect *cur;
+
+			cur = list_entry(cur_item, 
+					 struct ip_conntrack_expect,
+					 expected_list);
+			if (cur->sibling == NULL) {
+				old = cur;
+				break;
+			}
+		}
 
-	if (LIST_FIND(&expect_list, expect_clash,
-		      struct ip_conntrack_expect *, &related_to->expected)) {
+		/* (!old) cannot happen, since related_to->expecting is the
+		 * number of unconfirmed expects */
+		IP_NF_ASSERT(old);
+
+		/* newnat14 does not reuse the real allocated memory
+		 * structures but rather unexpects the old and
+		 * allocates a new.  unexpect_related will decrement
+		 * related_to->expecting. 
+		 */
+		unexpect_related(old);
+		ret = -EPERM;
+	} else if (LIST_FIND(&ip_conntrack_expect_list, expect_clash,
+			     struct ip_conntrack_expect *, &expect->tuple, 
+			     &expect->mask)) {
 		WRITE_UNLOCK(&ip_conntrack_lock);
+		DEBUGP("expect_related: busy!\n");
 		return -EBUSY;
 	}
+	
+	new = (struct ip_conntrack_expect *) 
+	      kmalloc(sizeof(struct ip_conntrack_expect), GFP_ATOMIC);
+	if (!new) {
+		WRITE_UNLOCK(&ip_conntrack_lock);
+		DEBUGP("expect_relaed: OOM allocating expect\n");
+		return -ENOMEM;
+	}
+	
+	/* Zero out the new structure, then fill out it with the data */
+	DEBUGP("new expectation %p of conntrack %p\n", new, related_to);
+	memset(new, 0, sizeof(*expect));
+	INIT_LIST_HEAD(&new->list);
+	INIT_LIST_HEAD(&new->expected_list);
+	memcpy(new, expect, sizeof(*expect));
+	new->expectant = related_to;
+	new->sibling = NULL;
+	/* increase usage count. This sucks. The memset above overwrites
+	 * old usage count [if still present] and we increase to one.  Only
+	 * works because everything is done under ip_conntrack_lock() */
+	atomic_inc(&new->use);
+	
+	/* add to expected list for this connection */	
+	list_add(&new->expected_list, &related_to->sibling_list);
+	/* add to global list of expectations */
+	list_prepend(&ip_conntrack_expect_list, &new->list);
+	/* add and start timer if required */
+	if (related_to->helper->timeout) {
+		init_timer(&new->timeout);
+		new->timeout.data = (unsigned long)new;
+		new->timeout.function = expectation_timed_out;
+		new->timeout.expires = jiffies + 
+					related_to->helper->timeout * HZ;
+		add_timer(&new->timeout);
+	}
+	related_to->expecting++;
 
-	list_prepend(&expect_list, &related_to->expected);
-	related_to->expected.expectant = related_to;
 	WRITE_UNLOCK(&ip_conntrack_lock);
 
-	return 0;
+	return ret;
 }
 
-void ip_conntrack_unexpect_related(struct ip_conntrack *related_to)
+/* Change tuple in an existing expectation */
+int ip_conntrack_change_expect(struct ip_conntrack_expect *expect,
+			       struct ip_conntrack_tuple *newtuple)
 {
-	WRITE_LOCK(&ip_conntrack_lock);
-	unexpect_related(related_to);
-	WRITE_UNLOCK(&ip_conntrack_lock);
-}
+	int ret;
+
+	MUST_BE_READ_LOCKED(&ip_conntrack_lock);
+	WRITE_LOCK(&ip_conntrack_expect_tuple_lock);
+
+	DEBUGP("change_expect:\n");
+	DEBUGP("exp tuple: "); DUMP_TUPLE(&expect->tuple);
+	DEBUGP("exp mask:  "); DUMP_TUPLE(&expect->mask);
+	DEBUGP("newtuple:  "); DUMP_TUPLE(newtuple);
+	if (expect->ct_tuple.dst.protonum == 0) {
+		/* Never seen before */
+		DEBUGP("change expect: never seen before\n");
+		if (!ip_ct_tuple_equal(&expect->tuple, newtuple) 
+		    && LIST_FIND(&ip_conntrack_expect_list, expect_clash,
+			         struct ip_conntrack_expect *, newtuple, &expect->mask)) {
+			/* Force NAT to find an unused tuple */
+			ret = -1;
+		} else {
+			memcpy(&expect->ct_tuple, &expect->tuple, sizeof(expect->tuple));
+			memcpy(&expect->tuple, newtuple, sizeof(expect->tuple));
+			ret = 0;
+		}
+	} else {
+		/* Resent packet */
+		DEBUGP("change expect: resent packet\n");
+		if (ip_ct_tuple_equal(&expect->tuple, newtuple)) {
+			ret = 0;
+		} else {
+			/* Force NAT to choose again the same port */
+			ret = -1;
+		}
+	}
+	WRITE_UNLOCK(&ip_conntrack_expect_tuple_lock);
 	
+	return ret;
+}
+
 /* Alter reply tuple (maybe alter helper).  If it's already taken,
    return 0 and don't do alteration. */
 int ip_conntrack_alter_reply(struct ip_conntrack *conntrack,
@@ -790,10 +1114,12 @@
 	DUMP_TUPLE(newreply);
 
 	conntrack->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
-	conntrack->helper = LIST_FIND(&helpers, helper_cmp,
-				      struct ip_conntrack_helper *,
-				      newreply);
+	if (!conntrack->master)
+		conntrack->helper = LIST_FIND(&helpers, helper_cmp,
+					      struct ip_conntrack_helper *,
+					      newreply);
 	WRITE_UNLOCK(&ip_conntrack_lock);
+
 	return 1;
 }
 
@@ -812,14 +1138,10 @@
 			 const struct ip_conntrack_helper *me)
 {
 	if (i->ctrack->helper == me) {
-		i->ctrack->helper = NULL;
 		/* Get rid of any expected. */
-		if (i->ctrack->expected.expectant) {
-			IP_NF_ASSERT(i->ctrack->expected.expectant
-				     == i->ctrack);
-			LIST_DELETE(&expect_list, &i->ctrack->expected);
-			i->ctrack->expected.expectant = NULL;
-		}
+		remove_expectations(i->ctrack);
+		/* And *then* set helper to NULL */
+		i->ctrack->helper = NULL;
 	}
 	return 0;
 }
@@ -1100,18 +1422,22 @@
 	}
 	ip_conntrack_max = 8 * ip_conntrack_htable_size;
 
-	printk("ip_conntrack (%u buckets, %d max)\n",
-	       ip_conntrack_htable_size, ip_conntrack_max);
+	printk("ip_conntrack version %s (%u buckets, %d max)"
+	       " - %d bytes per conntrack\n", IP_CONNTRACK_VERSION,
+	       ip_conntrack_htable_size, ip_conntrack_max,
+	       sizeof(struct ip_conntrack));
 
 	ret = nf_register_sockopt(&so_getorigdst);
-	if (ret != 0)
+	if (ret != 0) {
+		printk(KERN_ERR "Unable to register netfilter socket option\n");
 		return ret;
+	}
 
 	ip_conntrack_hash = vmalloc(sizeof(struct list_head)
 				    * ip_conntrack_htable_size);
 	if (!ip_conntrack_hash) {
-		nf_unregister_sockopt(&so_getorigdst);
-		return -ENOMEM;
+		printk(KERN_ERR "Unable to create ip_conntrack_hash\n");
+		goto err_unreg_sockopt;
 	}
 
 	ip_conntrack_cachep = kmem_cache_create("ip_conntrack",
@@ -1119,11 +1445,8 @@
 	                                        SLAB_HWCACHE_ALIGN, NULL, NULL);
 	if (!ip_conntrack_cachep) {
 		printk(KERN_ERR "Unable to create ip_conntrack slab cache\n");
-		vfree(ip_conntrack_hash);
-		nf_unregister_sockopt(&so_getorigdst);
-		return -ENOMEM;
+		goto err_free_hash;
 	}
-	
 	/* Don't NEED lock here, but good form anyway. */
 	WRITE_LOCK(&ip_conntrack_lock);
 	/* Sew in builtin protocols. */
@@ -1142,14 +1465,20 @@
 	ip_conntrack_sysctl_header
 		= register_sysctl_table(ip_conntrack_root_table, 0);
 	if (ip_conntrack_sysctl_header == NULL) {
-		kmem_cache_destroy(ip_conntrack_cachep);
-		vfree(ip_conntrack_hash);
-		nf_unregister_sockopt(&so_getorigdst);
-		return -ENOMEM;
+		goto err_free_ct_cachep;
 	}
 #endif /*CONFIG_SYSCTL*/
 
 	/* For use by ipt_REJECT */
 	ip_ct_attach = ip_conntrack_attach;
 	return ret;
+
+err_free_ct_cachep:
+	kmem_cache_destroy(ip_conntrack_cachep);
+err_free_hash:
+	vfree(ip_conntrack_hash);
+err_unreg_sockopt:
+	nf_unregister_sockopt(&so_getorigdst);
+
+	return -ENOMEM;
 }