source address lookup in kernel interface

use it for NAT detection if no source address known from config
  support for %any...%any connections

src/charon/kernel/kernel_interface.c

@@ -1342,6 +1342,84 @@ static status_t manage_srcroute(private_kernel_interface_t *this, int nlmsg_type
 	return netlink_send_ack(this, this->socket_rt, hdr);
 }
 
+/**
+ * Implementation of kernel_interface_t.get_source_addr.
+ */
+static host_t* get_source_addr(private_kernel_interface_t *this, host_t *dest)
+{
+	unsigned char request[BUFFER_SIZE];
+	struct nlmsghdr *hdr, *out, *current;
+	struct rtmsg *msg;
+	chunk_t chunk;
+	size_t len;
+	host_t *source = NULL;
+	
+	memset(&request, 0, sizeof(request));
+
+	hdr = (struct nlmsghdr*)request;
+	hdr->nlmsg_flags = NLM_F_REQUEST;
+	hdr->nlmsg_type = RTM_GETROUTE;
+	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
+
+	msg = (struct rtmsg*)NLMSG_DATA(hdr);
+	msg->rtm_family = dest->get_family(dest);
+	msg->rtm_dst_len = msg->rtm_family == AF_INET ? 32 : 128;
+	msg->rtm_table = RT_TABLE_MAIN;
+	msg->rtm_protocol = RTPROT_STATIC;
+	msg->rtm_type = RTN_UNICAST;
+	msg->rtm_scope = RT_SCOPE_UNIVERSE;
+	
+	chunk = dest->get_address(dest);
+	add_attribute(hdr, RTA_DST, chunk, sizeof(request));
+			
+	if (netlink_send(this, this->socket_rt, hdr, &out, &len) != SUCCESS)
+	{
+		DBG1(DBG_KNL, "getting source address to %H failed", dest);
+		return NULL;
+	}
+	current = out;
+	while (NLMSG_OK(current, len))
+	{
+		switch (current->nlmsg_type)
+		{
+			case NLMSG_DONE:
+				break;
+			case RTM_NEWROUTE:
+			{
+				struct rtattr *rta;
+				size_t rtasize;
+				
+				msg = (struct rtmsg*)(NLMSG_DATA(current));
+				rta = RTM_RTA(msg);
+				rtasize = RTM_PAYLOAD(current);
+				while(RTA_OK(rta, rtasize))
+				{
+					switch (rta->rta_type)
+					{
+						case RTA_PREFSRC:
+							chunk.ptr = RTA_DATA(rta);
+							chunk.len = RTA_PAYLOAD(rta);
+							source = host_create_from_chunk(msg->rtm_family, 
+															chunk, 0);
+							break;
+					}
+					rta = RTA_NEXT(rta, rtasize);
+				}
+				break;
+			}
+			default:
+				current = NLMSG_NEXT(current, len);
+				continue;
+		}
+		break;
+	}
+	if (source == NULL)
+	{
+		DBG1(DBG_KNL, "no route found to %H", dest);
+	}
+	free(out);
+	return source;
+}
 
 /**
  * Implementation of kernel_interface_t.add_ip.
@@ -2209,9 +2287,9 @@ kernel_interface_t *kernel_interface_create()
 	this->public.add_policy = (status_t(*)(kernel_interface_t*,host_t*,host_t*,traffic_selector_t*,traffic_selector_t*,policy_dir_t,protocol_id_t,u_int32_t,bool,mode_t,bool))add_policy;
 	this->public.query_policy = (status_t(*)(kernel_interface_t*,traffic_selector_t*,traffic_selector_t*,policy_dir_t,u_int32_t*))query_policy;
 	this->public.del_policy = (status_t(*)(kernel_interface_t*,traffic_selector_t*,traffic_selector_t*,policy_dir_t))del_policy;
-
 	this->public.get_interface = (char*(*)(kernel_interface_t*,host_t*))get_interface_name;
 	this->public.create_address_iterator = (iterator_t*(*)(kernel_interface_t*))create_address_iterator;
+	this->public.get_source_addr = (host_t*(*)(kernel_interface_t*, host_t *dest))get_source_addr;
 	this->public.add_ip = (status_t(*)(kernel_interface_t*,host_t*,host_t*)) add_ip;
 	this->public.del_ip = (status_t(*)(kernel_interface_t*,host_t*,host_t*)) del_ip;
 	this->public.destroy = (void(*)(kernel_interface_t*)) destroy;

src/charon/kernel/kernel_interface.h

@@ -267,6 +267,18 @@ struct kernel_interface_t {
 							traffic_selector_t *dst_ts,
 							policy_dir_t direction);
 	
+	/**
+	 * @brief Get our outgoing source address for a destination.
+	 *
+	 * Does a route lookup to get the source address used to reach dest.
+	 * The returned host is allocated and must be destroyed.
+	 *
+	 * @param this			calling object
+	 * @param dest			target destination address
+	 * @return				outgoing source address, NULL if unreachable
+	 */
+	host_t* (*get_source_addr)(kernel_interface_t *this, host_t *dest);
+	
 	/**
 	 * @brief Get the interface name of a local address.
 	 *

src/charon/sa/ike_sa.c

@@ -763,7 +763,7 @@ static status_t process_message(private_ike_sa_t *this, message_t *message)
 		}
 		
 		/* check if message is trustworthy, and update host information */
-		if (this->state == IKE_CREATED ||
+		if (this->state == IKE_CREATED || this->state == IKE_CONNECTING ||
 			message->get_exchange_type(message) != IKE_SA_INIT)
 		{
 			update_hosts(this, me, other);

src/charon/sa/tasks/ike_natd.c

@@ -243,29 +243,45 @@ static status_t build_i(private_ike_natd_t *this, message_t *message)
 	iterator_t *iterator;
 	host_t *host;
 	
-	/* include one notify if our address is defined, all addresses otherwise */
-	host = this->ike_sa->get_my_host(this->ike_sa);
-	if (host->is_anyaddr(host))
-	{
-		iterator = charon->kernel_interface->create_address_iterator(
-													charon->kernel_interface);
-		while (iterator->iterate(iterator, (void**)&host))
-		{
-			notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
-			message->add_payload(message, (payload_t*)notify);
-		}
-		iterator->destroy(iterator);
-	}
-	else
-	{
-		notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
-		message->add_payload(message, (payload_t*)notify);
-	}
-	
+	/* destination is always set */
 	host = this->ike_sa->get_other_host(this->ike_sa);
 	notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, host);
 	message->add_payload(message, (payload_t*)notify);
 	
+	/* source may be any, we have 3 possibilities to get our source address:
+	 * 1. It is defined in the config => use the one of the IKE_SA
+	 * 2. We do a routing lookup in the kernel interface
+	 * 3. Include all possbile addresses
+	 */
+	host = this->ike_sa->get_my_host(this->ike_sa);
+	if (!host->is_anyaddr(host))
+	{	/* 1. */
+		notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
+		message->add_payload(message, (payload_t*)notify);
+	}
+	else
+	{
+		host = charon->kernel_interface->get_source_addr(
+									charon->kernel_interface,
+									this->ike_sa->get_other_host(this->ike_sa));
+		if (host)
+		{	/* 2. */
+			notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
+			message->add_payload(message, (payload_t*)notify);
+			host->destroy(host);
+		}
+		else
+		{	/* 3. */
+			iterator = charon->kernel_interface->create_address_iterator(
+													charon->kernel_interface);
+			while (iterator->iterate(iterator, (void**)&host))
+			{
+				notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
+				message->add_payload(message, (payload_t*)notify);
+			}
+			iterator->destroy(iterator);
+		}
+	}
 	return NEED_MORE;
 }