Define an interface for SASL mechanisms and provide a static factory

src/libpttls/Makefile.am

@@ -7,4 +7,5 @@ libpttls_la_LIBADD = $(top_builddir)/src/libtls/libtls.la
 libpttls_la_SOURCES = pt_tls.c pt_tls.h \
 	pt_tls_client.c pt_tls_client.h \
 	pt_tls_server.c pt_tls_server.h \
-	pt_tls_dispatcher.c pt_tls_dispatcher.h
+	pt_tls_dispatcher.c pt_tls_dispatcher.h \
+	sasl/sasl_mechanism.c sasl/sasl_mechanism.h

src/libpttls/sasl/sasl_mechanism.c

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2013 Martin Willi
+ * Copyright (C) 2013 revosec AG
+ *
+ * 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
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+#include "sasl_mechanism.h"
+
+/**
+ * Available SASL mechanisms.
+ */
+static struct {
+	char *name;
+	bool server;
+	sasl_mechanism_constructor_t create;
+} mechs[] = {
+};
+
+/**
+ * See header.
+ */
+sasl_mechanism_t *sasl_mechanism_create(char *name, identification_t *client)
+{
+	int i;
+
+	for (i = 0; i < countof(mechs); i++)
+	{
+		if (streq(mechs[i].name, name) && mechs[i].server == (client == NULL))
+		{
+			return mechs[i].create(name, client);
+		}
+	}
+	return NULL;
+}
+
+/**
+ * SASL mechanism enumerator
+ */
+typedef struct {
+	/** implements enumerator_t */
+	enumerator_t public;
+	/** looking for client or server? */
+	bool server;
+	/** position in mechs[] */
+	int i;
+} mech_enumerator_t;
+
+METHOD(enumerator_t, mech_enumerate, bool,
+	mech_enumerator_t *this, char **name)
+{
+	while (this->i < countof(mechs))
+	{
+		if (mechs[this->i].server == this->server)
+		{
+			*name = mechs[this->i].name;
+			this->i++;
+			return TRUE;
+		}
+		this->i++;
+	}
+	return FALSE;
+}
+
+/**
+ * See header.
+ */
+enumerator_t* sasl_mechanism_create_enumerator(bool server)
+{
+	mech_enumerator_t *enumerator;
+
+	INIT(enumerator,
+		.public = {
+			.enumerate = (void*)_mech_enumerate,
+			.destroy = (void*)free,
+		},
+		.server = server,
+	);
+	return &enumerator->public;
+}

src/libpttls/sasl/sasl_mechanism.h

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2013 Martin Willi
+ * Copyright (C) 2013 revosec AG
+ *
+ * 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
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup sasl_mechanism sasl_mechanism
+ * @{ @ingroup sasl
+ */
+
+#ifndef SASL_MECHANISM_H_
+#define SASL_MECHANISM_H_
+
+typedef struct sasl_mechanism_t sasl_mechanism_t;
+
+#include <library.h>
+
+/**
+ * Constructor function for SASL mechansims.
+ *
+ * @param name			name of the requested SASL mechanism
+ * @param client		client identity, NULL to act as server
+ * @return				SASL mechanism, NULL on failure
+ */
+typedef sasl_mechanism_t*(*sasl_mechanism_constructor_t)(char *name,
+													identification_t *client);
+
+/**
+ * Generic interface for SASL mechanisms.
+ */
+struct sasl_mechanism_t {
+
+	/**
+	 * Get the name of this SASL mechanism.
+	 *
+	 * @return			name of SASL mechanism
+	 */
+	char* (*get_name)(sasl_mechanism_t *this);
+
+	/**
+	 * Build a SASL message to send to remote host.
+	 *
+	 * A message is returned if the return value is NEED_MORE or SUCCESS. A
+	 * client MUST NOT return SUCCESS in build(), as the final message
+	 * is always from server to client (even if it is an empty result message).
+	 *
+	 * @param message	receives allocated SASL message, to free
+	 * @return
+	 *					- FAILED if mechanism failed
+	 *					- NEED_MORE if additional exchanges required
+	 *					- INVALID_STATE if currently nothing to build
+	 *					- SUCCESS if mechanism authenticated successfully
+	 */
+	status_t (*build)(sasl_mechanism_t *this, chunk_t *message);
+
+	/**
+	 * Process a SASL message received from remote host.
+	 *
+	 * If a server returns SUCCESS during process(), an empty result message
+	 * is sent to complete the SASL exchange.
+	 *
+	 * @param message	received SASL message to process
+	 * @return
+	 *					- FAILED if mechanism failed
+	 *					- NEED_MORE if additional exchanges required
+	 *					- SUCCESS if mechanism authenticated successfully
+	 */
+	status_t (*process)(sasl_mechanism_t *this, chunk_t message);
+
+	/**
+	 * Destroy a sasl_mechanism_t.
+	 */
+	void (*destroy)(sasl_mechanism_t *this);
+};
+
+/**
+ * Create a sasl_mechanism instance.
+ *
+ * @param name			name of SASL mechanism to create
+ * @param client		client identity, NULL to act as server
+ * @return				SASL mechanism instance, NULL if not found
+ */
+sasl_mechanism_t *sasl_mechanism_create(char *name, identification_t *client);
+
+/**
+ * Create an enumerator over supported SASL mechanism names.
+ *
+ * @param server		TRUE for server instance, FALSE for client
+ * @return				enumerator over char*
+ */
+enumerator_t* sasl_mechanism_create_enumerator(bool server);
+
+#endif /** SASL_MECHANISM_H_ @}*/