Store proposal number in proposal_t to reuse it in the selected proposal

According to RFC 5996 3.3.1, we MUST reuse the proposal number of
the selected proposal in the SA payload reply.

src/libcharon/config/proposal.c

@@ -87,6 +87,11 @@ struct private_proposal_t {
 	 * senders SPI
 	 */
 	u_int64_t spi;
+
+	/**
+	 * Proposal number
+	 */
+	u_int number;
 };
 
 /**
@@ -311,7 +316,7 @@ METHOD(proposal_t, select_proposal, proposal_t*,
 		return NULL;
 	}
 
-	selected = proposal_create(this->protocol);
+	selected = proposal_create(this->protocol, other->number);
 
 	/* select encryption algorithm */
 	if (select_algo(this->encryption_algos, other->encryption_algos, private,
@@ -473,6 +478,12 @@ static bool algo_list_equals(linked_list_t *l1, linked_list_t *l2)
 	return equals;
 }
 
+METHOD(proposal_t, get_number, u_int,
+	private_proposal_t *this)
+{
+	return this->number;
+}
+
 METHOD(proposal_t, equals, bool,
 	private_proposal_t *this, proposal_t *other_pub)
 {
@@ -493,8 +504,9 @@ METHOD(proposal_t, equals, bool,
 METHOD(proposal_t, clone_, proposal_t*,
 	private_proposal_t *this)
 {
-	private_proposal_t *clone = (private_proposal_t*)proposal_create(this->protocol);
+	private_proposal_t *clone;
 
+	clone = (private_proposal_t*)proposal_create(this->protocol, 0);
 	clone_algo_list(this->encryption_algos, clone->encryption_algos);
 	clone_algo_list(this->integrity_algos, clone->integrity_algos);
 	clone_algo_list(this->prf_algos, clone->prf_algos);
@@ -502,6 +514,7 @@ METHOD(proposal_t, clone_, proposal_t*,
 	clone_algo_list(this->esns, clone->esns);
 
 	clone->spi = this->spi;
+	clone->number = this->number;
 
 	return &clone->public;
 }
@@ -685,7 +698,7 @@ METHOD(proposal_t, destroy, void,
 /*
  * Describtion in header-file
  */
-proposal_t *proposal_create(protocol_id_t protocol)
+proposal_t *proposal_create(protocol_id_t protocol, u_int number)
 {
 	private_proposal_t *this;
 
@@ -700,11 +713,13 @@ proposal_t *proposal_create(protocol_id_t protocol)
 			.get_protocol = _get_protocol,
 			.set_spi = _set_spi,
 			.get_spi = _get_spi,
+			.get_number = _get_number,
 			.equals = _equals,
 			.clone = _clone_,
 			.destroy = _destroy,
 		},
 		.protocol = protocol,
+		.number = number,
 		.encryption_algos = linked_list_create(),
 		.integrity_algos = linked_list_create(),
 		.prf_algos = linked_list_create(),
@@ -837,7 +852,7 @@ static void proposal_add_supported_ike(private_proposal_t *this)
  */
 proposal_t *proposal_create_default(protocol_id_t protocol)
 {
-	private_proposal_t *this = (private_proposal_t*)proposal_create(protocol);
+	private_proposal_t *this = (private_proposal_t*)proposal_create(protocol, 0);
 
 	switch (protocol)
 	{
@@ -872,7 +887,7 @@ proposal_t *proposal_create_default(protocol_id_t protocol)
  */
 proposal_t *proposal_create_from_string(protocol_id_t protocol, const char *algs)
 {
-	private_proposal_t *this = (private_proposal_t*)proposal_create(protocol);
+	private_proposal_t *this = (private_proposal_t*)proposal_create(protocol, 0);
 	chunk_t string = {(void*)algs, strlen(algs)};
 	chunk_t alg;
 	status_t status = SUCCESS;

src/libcharon/config/proposal.h

@@ -160,6 +160,13 @@ struct proposal_t {
 	 */
 	void (*set_spi) (proposal_t *this, u_int64_t spi);
 
+	/**
+	 * Get the proposal number, as encoded in SA payload
+	 *
+	 * @return				proposal number
+	 */
+	u_int (*get_number)(proposal_t *this);
+
 	/**
 	 * Check for the eqality of two proposals.
 	 *
@@ -185,9 +192,10 @@ struct proposal_t {
  * Create a child proposal for AH, ESP or IKE.
  *
  * @param protocol			protocol, such as PROTO_ESP
+ * @param number			proposal number, as encoded in SA payload
  * @return 					proposal_t object
  */
-proposal_t *proposal_create(protocol_id_t protocol);
+proposal_t *proposal_create(protocol_id_t protocol, u_int number);
 
 /**
  * Create a default proposal if nothing further specified.

src/libcharon/encoding/payloads/proposal_substructure.c

@@ -309,7 +309,7 @@ METHOD(proposal_substructure_t, get_proposal, proposal_t*,
 	proposal_t *proposal;
 	u_int64_t spi;
 
-	proposal = proposal_create(this->protocol_id);
+	proposal = proposal_create(this->protocol_id, this->proposal_number);
 
 	enumerator = this->transforms->create_enumerator(this->transforms);
 	while (enumerator->enumerate(enumerator, &transform))
@@ -498,7 +498,7 @@ proposal_substructure_t *proposal_substructure_create_from_proposal(
 		default:
 			break;
 	}
-	this->proposal_number = 0;
+	this->proposal_number = proposal->get_number(proposal);
 	this->protocol_id = proposal->get_protocol(proposal);
 
 	return &this->public;

src/libcharon/encoding/payloads/sa_payload.c

@@ -204,8 +204,15 @@ METHOD(sa_payload_t, add_proposal, void,
 		last->set_is_last_proposal(last, FALSE);
 	}
 	substruct->set_is_last_proposal(substruct, TRUE);
-	substruct->set_proposal_number(substruct, count + 1);
-	this->proposals->insert_last(this->proposals, proposal);
+	if (proposal->get_number(proposal))
+	{	/* use the selected proposals number, if any */
+		substruct->set_proposal_number(substruct, proposal->get_number(proposal));
+	}
+	else
+	{
+		substruct->set_proposal_number(substruct, count + 1);
+	}
+	this->proposals->insert_last(this->proposals, substruct);
 	compute_length(this);
 }
 

src/libcharon/plugins/ha/ha_dispatcher.c

@@ -136,7 +136,7 @@ static void process_ike_add(private_ha_dispatcher_t *this, ha_message_t *message
 		diffie_hellman_t dh = { .get_shared_secret = get_shared_secret,
 								.destroy = (void*)&secret };
 
-		proposal = proposal_create(PROTO_IKE);
+		proposal = proposal_create(PROTO_IKE, 0);
 		keymat = ike_sa->get_keymat(ike_sa);
 		if (integ)
 		{
@@ -549,7 +549,7 @@ static void process_child_add(private_ha_dispatcher_t *this,
 	child_sa->set_protocol(child_sa, PROTO_ESP);
 	child_sa->set_ipcomp(child_sa, ipcomp);
 
-	proposal = proposal_create(PROTO_ESP);
+	proposal = proposal_create(PROTO_ESP, 0);
 	if (integ)
 	{
 		proposal->add_algorithm(proposal, INTEGRITY_ALGORITHM, integ, 0);