key-exchange: Add dynamic parser for additional key exchange methods

src/libstrongswan/crypto/key_exchange.c

@@ -18,6 +18,9 @@
 
 #include "key_exchange.h"
 
+#include <collections/hashtable.h>
+#include <threading/mutex.h>
+
 ENUM_BEGIN(key_exchange_method_names, KE_NONE, MODP_1024_BIT,
 	"KE_NONE",
 	"MODP_768",
@@ -475,10 +478,68 @@ static struct {
 	},
 };
 
+/**
+ * Proposal tokens for additional key exchanges.
+ */
+static hashtable_t *tokens;
+
+/**
+ * Mutex to safely access cached tokens.
+ */
+static mutex_t *mutex;
+
+/**
+ * Destroy an allocated proposal token.
+ */
+static void token_destroy(proposal_token_t *this)
+{
+	free(this->name);
+	free(this);
+}
+
+/**
+ * Parse ke<1-7>_<method> for additional key exchange methods.
+ */
+static proposal_token_t *additional_key_exchange_parser(const char *algname)
+{
+	proposal_token_t *token;
+	const proposal_token_t *base;
+	u_int num;
+	char prefix[3], alg[256];
+
+	if (!algname || sscanf(algname, "%2s%1u_%255s", &prefix, &num, alg) != 3 ||
+		!strcaseeq(prefix, "ke"))
+	{
+		return NULL;
+	}
+	mutex->lock(mutex);
+	token = tokens->get(tokens, algname);
+	if (token || num < 1 || num > 7)
+	{
+		goto done;
+	}
+	base = lib->proposal->get_token(lib->proposal, alg);
+	if (!base || base->type != KEY_EXCHANGE_METHOD)
+	{
+		goto done;
+	}
+	INIT(token,
+		.name = strdup(algname),
+		.type = ADDITIONAL_KEY_EXCHANGE_1 + num - 1,
+		.algorithm = base->algorithm,
+		.keysize = base->keysize,
+	);
+	tokens->put(tokens, token->name, token);
+
+done:
+	mutex->unlock(mutex);
+	return token;
+}
+
 /*
  * Described in header
  */
-void diffie_hellman_init()
+void key_exchange_init()
 {
 	int i;
 
@@ -498,6 +559,20 @@ void diffie_hellman_init()
 			dh_params[i].public.exp_len = dh_params[i].public.prime.len;
 		}
 	}
+
+	mutex = mutex_create(MUTEX_TYPE_RECURSIVE);
+	tokens = hashtable_create(hashtable_hash_str, hashtable_equals_str, 4);
+	lib->proposal->register_algname_parser(lib->proposal,
+										   additional_key_exchange_parser);
+}
+
+/*
+ * Described in header
+ */
+void key_exchange_deinit()
+{
+	tokens->destroy_function(tokens, (void*)token_destroy);
+	mutex->destroy(mutex);
 }
 
 /*

src/libstrongswan/crypto/key_exchange.h

@@ -178,9 +178,14 @@ struct diffie_hellman_params_t {
 };
 
 /**
- * Initialize diffie hellman parameters during startup.
+ * Initialize DH parameters and KE token parser during startup.
  */
-void diffie_hellman_init();
+void key_exchange_init();
+
+/**
+ * Deinitialize KE token parser during shutdown.
+ */
+void key_exchange_deinit();
 
 /**
  * Get the parameters associated with the specified Diffie-Hellman group.

src/libstrongswan/library.c

@@ -161,6 +161,8 @@ void library_deinit()
 	/* make sure the cache is clear before unloading plugins */
 	lib->credmgr->flush_cache(lib->credmgr, CERT_ANY);
 
+	key_exchange_deinit();
+
 	this->public.streams->destroy(this->public.streams);
 	this->public.watcher->destroy(this->public.watcher);
 	this->public.scheduler->destroy(this->public.scheduler);
@@ -436,7 +438,7 @@ bool library_init(char *settings, const char *namespace)
 #endif /* INTEGRITY_TEST */
 	}
 
-	diffie_hellman_init();
+	key_exchange_init();
 
 	return !this->init_failed;
 }