proposal: Copy SPI and proposal number from correct proposal in select()

If charon.prefer_configured_proposals is disabled select() is called on
the received proposal. This incorrectly set the SPI to 0 as the
configured proposal has no SPI set.

Fixes #2190.

src/libcharon/config/child_cfg.c

@@ -249,7 +249,7 @@ METHOD(child_cfg_t, select_proposal, proposal_t*,
 			{
 				proposal->strip_dh(proposal, MODP_NONE);
 			}
-			selected = proposal->select(proposal, match, private);
+			selected = proposal->select(proposal, match, prefer_self, private);
 			if (selected)
 			{
 				DBG2(DBG_CFG, "received proposals: %#P", proposals);

src/libcharon/config/ike_cfg.c

@@ -339,7 +339,7 @@ METHOD(ike_cfg_t, select_proposal, proposal_t*,
 		}
 		while (match_enum->enumerate(match_enum, (void**)&match))
 		{
-			selected = proposal->select(proposal, match, private);
+			selected = proposal->select(proposal, match, prefer_self, private);
 			if (selected)
 			{
 				DBG2(DBG_CFG, "received proposals: %#P", proposals);

src/libcharon/config/proposal.c

@@ -273,7 +273,8 @@ static bool select_algo(private_proposal_t *this, proposal_t *other,
 }
 
 METHOD(proposal_t, select_proposal, proposal_t*,
-	private_proposal_t *this, proposal_t *other, bool private)
+	private_proposal_t *this, proposal_t *other, bool other_remote,
+	bool private)
 {
 	proposal_t *selected;
 
@@ -285,7 +286,17 @@ METHOD(proposal_t, select_proposal, proposal_t*,
 		return NULL;
 	}
 
-	selected = proposal_create(this->protocol, other->get_number(other));
+	if (other_remote)
+	{
+		selected = proposal_create(this->protocol, other->get_number(other));
+		selected->set_spi(selected, other->get_spi(other));
+	}
+	else
+	{
+		selected = proposal_create(this->protocol, this->number);
+		selected->set_spi(selected, this->spi);
+
+	}
 
 	if (!select_algo(this, other, selected, ENCRYPTION_ALGORITHM, private) ||
 		!select_algo(this, other, selected, PSEUDO_RANDOM_FUNCTION, private) ||
@@ -298,7 +309,6 @@ METHOD(proposal_t, select_proposal, proposal_t*,
 	}
 
 	DBG2(DBG_CFG, "  proposal matches");
-	selected->set_spi(selected, other->get_spi(other));
 	return selected;
 }
 

src/libcharon/config/proposal.h

@@ -1,6 +1,7 @@
 /*
+ * Copyright (C) 2009-2016 Tobias Brunner
  * Copyright (C) 2006 Martin Willi
- * Hochschule fuer Technik Rapperswil
+ * HSR Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -124,10 +125,14 @@ struct proposal_t {
 	 * in common, a resulting proposal of this kind is created.
 	 *
 	 * @param other			proposal to compare against
+	 * @param other_remote	whether other is the remote proposal from which to
+	 *						copy SPI and proposal number to the result,
+	 *						otherwise copy from this proposal
 	 * @param private		accepts algorithms allocated in a private range
 	 * @return				selected proposal, NULL if proposals don't match
 	 */
-	proposal_t *(*select) (proposal_t *this, proposal_t *other, bool private);
+	proposal_t *(*select)(proposal_t *this, proposal_t *other,
+						  bool other_remote, bool private);
 
 	/**
 	 * Get the protocol ID of the proposal.