Perform string-based lookup of method-related information only once

24 files changed, 445 insertions, 417 deletions

diff --git a/src/config.c b/src/config.c
index ed4a8d7..726d04c 100644
--- a/src/config.c
+++ b/src/config.c
@@ -27,6 +27,7 @@
 #include "fastd.h"
 #include "config.h"
 #include "lex.h"
+#include "method.h"
 #include "peer.h"
 #include <config.yy.h>
 
@@ -87,22 +88,17 @@ bool fastd_config_protocol(fastd_context_t *ctx UNUSED, fastd_config_t *conf, co
 	return true;
 }
 
-bool fastd_config_method(fastd_context_t *ctx, fastd_config_t *conf, const char *name) {
-	if (!fastd_method_get_by_name(name))
-		return false;
-
+void fastd_config_method(fastd_context_t *ctx, fastd_config_t *conf, const char *name) {
 	fastd_string_stack_t **method;
 
-	for (method = &conf->methods; *method; method = &(*method)->next) {
+	for (method = &conf->method_list; *method; method = &(*method)->next) {
 		if (!strcmp((*method)->str, name)) {
 			pr_debug(ctx, "duplicate method name `%s', ignoring", name);
-			return true;
+			return;
 		}
 	}
 
 	*method = fastd_string_stack_dup(name);
-
-	return true;
 }
 
 bool fastd_config_bind_address(fastd_context_t *ctx UNUSED, fastd_config_t *conf, const fastd_peer_address_t *address, const char *bindtodev, bool default_v4, bool default_v6) {
@@ -482,9 +478,9 @@ static void configure_method_parameters(fastd_config_t *conf) {
 	conf->min_encrypt_tail_space = 0;
 	conf->min_decrypt_tail_space = 0;
 
-	fastd_string_stack_t *method_name;
-	for (method_name = conf->methods; method_name; method_name = method_name->next) {
-		const fastd_method_t *method = fastd_method_get_by_name(method_name->str);
+	size_t i;
+	for (i = 0; conf->methods[i].name; i++) {
+		const fastd_method_t *method = conf->methods[i].method;
 
 		conf->max_overhead = max_size_t(conf->max_overhead, method->max_overhead);
 		conf->min_encrypt_head_space = max_size_t(conf->min_encrypt_head_space, method->min_encrypt_head_space);
@@ -499,6 +495,32 @@ static void configure_method_parameters(fastd_config_t *conf) {
 	conf->min_decrypt_head_space = alignto(conf->min_decrypt_head_space, 16) + 8;
 }
 
+static void configure_methods(fastd_context_t *ctx, fastd_config_t *conf) {
+	size_t n_methods = 0, i;
+	fastd_string_stack_t *method_name;
+	for (method_name = conf->method_list; method_name; method_name = method_name->next)
+		n_methods++;
+
+	conf->methods = calloc(n_methods+1, sizeof(fastd_method_info_t));
+
+	for (i = 0, method_name = conf->method_list; method_name; i++, method_name = method_name->next) {
+		conf->methods[i].name = method_name->str;
+		if (!fastd_method_create_by_name(method_name->str, &conf->methods[i].method, &conf->methods[i].ctx))
+			exit_error(ctx, "method `%s' not supported", method_name->str);
+	}
+
+	configure_method_parameters(conf);
+}
+
+static void destroy_methods(fastd_config_t *conf) {
+	size_t i;
+	for (i = 0; conf->methods[i].name; i++) {
+		conf->methods[i].method->destroy(conf->methods[i].ctx);
+	}
+
+	free(conf->methods);
+}
+
 void fastd_configure(fastd_context_t *ctx, fastd_config_t *conf, int argc, char *const argv[]) {
 	default_config(conf);
 
@@ -534,17 +556,16 @@ void fastd_configure(fastd_context_t *ctx, fastd_config_t *conf, int argc, char
 		exit_error(ctx, "config error: setting pmtu is not supported on this system");
 #endif
 
-	if (!conf->methods) {
+	if (!conf->method_list) {
 		pr_warn(ctx, "no encryption method configured, falling back to method `null' (unencrypted)");
-		if (!fastd_config_method(ctx, conf, "null"))
-			exit_error(ctx, "method `null' not supported");
+		fastd_config_method(ctx, conf, "null");
 	}
 
 	if (!conf->secure_handshakes_set)
 		pr_warn(ctx, "`secure handshakes' not set, please read the documentation about this option; defaulting to no");
 
 	configure_user(ctx, conf);
-	configure_method_parameters(conf);
+	configure_methods(ctx, conf);
 }
 
 static void peer_dirs_read_peer_group(fastd_context_t *ctx, fastd_config_t *new_conf) {
@@ -645,7 +666,8 @@ void fastd_config_release(fastd_context_t *ctx, fastd_config_t *conf) {
 
 	free_peer_group(conf->peer_group);
 
-	fastd_string_stack_free(conf->methods);
+	destroy_methods(conf);
+	fastd_string_stack_free(conf->method_list);
 
 	fastd_mac_config_free(conf->macs);
 	fastd_cipher_config_free(conf->ciphers);
diff --git a/src/config.h b/src/config.h
index a4777c7..ad3d6b1 100644
--- a/src/config.h
+++ b/src/config.h
@@ -31,7 +31,7 @@
 
 
 bool fastd_config_protocol(fastd_context_t *ctx, fastd_config_t *conf, const char *name);
-bool fastd_config_method(fastd_context_t *ctx, fastd_config_t *conf, const char *name);
+void fastd_config_method(fastd_context_t *ctx, fastd_config_t *conf, const char *name);
 bool fastd_config_add_log_file(fastd_context_t *ctx, fastd_config_t *conf, const char *name, fastd_loglevel_t level);
 bool fastd_config_bind_address(fastd_context_t *ctx, fastd_config_t *conf, const fastd_peer_address_t *address, const char *bindtodev, bool default_v4, bool default_v6);
 void fastd_config_peer_group_push(fastd_context_t *ctx, fastd_config_t *conf, const char *name);
diff --git a/src/config.y b/src/config.y
index a79e8e9..68d41a4 100644
--- a/src/config.y
+++ b/src/config.y
@@ -350,10 +350,7 @@ protocol:	TOK_STRING {
 	;
 
 method:		TOK_STRING {
-			if (!fastd_config_method(ctx, conf, $1->str)) {
-				fastd_config_error(&@$, ctx, conf, filename, depth, "unsupported method");
-				YYERROR;
-			}
+			fastd_config_method(ctx, conf, $1->str);
 		}
 	;
 
diff --git a/src/crypto.h b/src/crypto.h
index 7ee73cd..1f26058 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -58,9 +58,9 @@ struct fastd_mac {
 
 
 const fastd_cipher_info_t* fastd_cipher_info_get_by_name(const char *name);
-const fastd_cipher_t* fastd_cipher_get_by_name(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **info);
+const fastd_cipher_t* fastd_cipher_get(fastd_context_t *ctx, const fastd_cipher_info_t *info);
 
 const fastd_mac_info_t* fastd_mac_info_get_by_name(const char *name);
-const fastd_mac_t* fastd_mac_get_by_name(fastd_context_t *ctx, const char *name, const fastd_mac_info_t **info);
+const fastd_mac_t* fastd_mac_get(fastd_context_t *ctx, const fastd_mac_info_t *info);
 
 #endif /* _FASTD_CRYPTO_H_ */
diff --git a/src/crypto/cipher/ciphers.c.in b/src/crypto/cipher/ciphers.c.in
index 72ea3d2..cdc9911 100644
--- a/src/crypto/cipher/ciphers.c.in
+++ b/src/crypto/cipher/ciphers.c.in
@@ -106,15 +106,11 @@ const fastd_cipher_info_t* fastd_cipher_info_get_by_name(const char *name) {
 	return NULL;
 }
 
-const fastd_cipher_t* fastd_cipher_get_by_name(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **info) {
+const fastd_cipher_t* fastd_cipher_get(fastd_context_t *ctx, const fastd_cipher_info_t *info) {
 	size_t i;
 	for (i = 0; i < array_size(ciphers); i++) {
-		if (!strcmp(ciphers[i].name, name)) {
-			if (info)
-				*info = ciphers[i].info;
-
+		if (ciphers[i].info == info)
 			return ctx->conf->ciphers[i];
-		}
 	}
 
 	return NULL;
diff --git a/src/crypto/mac/macs.c.in b/src/crypto/mac/macs.c.in
index c70473b..ee64362 100644
--- a/src/crypto/mac/macs.c.in
+++ b/src/crypto/mac/macs.c.in
@@ -106,15 +106,11 @@ const fastd_mac_info_t* fastd_mac_info_get_by_name(const char *name) {
 	return NULL;
 }
 
-const fastd_mac_t* fastd_mac_get_by_name(fastd_context_t *ctx, const char *name, const fastd_mac_info_t **info) {
+const fastd_mac_t* fastd_mac_get(fastd_context_t *ctx, const fastd_mac_info_t *info) {
 	size_t i;
 	for (i = 0; i < array_size(macs); i++) {
-		if (!strcmp(macs[i].name, name)) {
-			if (info)
-				*info = macs[i].info;
-
+		if (macs[i].info == info)
 			return ctx->conf->macs[i];
-		}
 	}
 
 	return NULL;
diff --git a/src/fastd.h b/src/fastd.h
index 4290421..ebbcf86 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -63,7 +63,7 @@ struct fastd_protocol {
 	bool (*peer_check_temporary)(fastd_context_t *ctx, fastd_peer_t *peer);
 
 	void (*handshake_init)(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer);
-	void (*handshake_handle)(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const fastd_handshake_t *handshake, const char *method);
+	void (*handshake_handle)(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const fastd_handshake_t *handshake, const fastd_method_info_t *method);
 
 	void (*handle_recv)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer);
 	void (*send)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer);
@@ -78,28 +78,6 @@ struct fastd_protocol {
 	bool (*describe_peer)(const fastd_context_t *ctx, const fastd_peer_t *peer, char *buf, size_t len);
 };
 
-struct fastd_method {
-	bool (*provides)(const char *name);
-
-	size_t max_overhead;
-	size_t min_encrypt_head_space;
-	size_t min_decrypt_head_space;
-	size_t min_encrypt_tail_space;
-	size_t min_decrypt_tail_space;
-
-	size_t (*key_length)(fastd_context_t *ctx, const char *name);
-	fastd_method_session_state_t* (*session_init)(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator);
-	fastd_method_session_state_t* (*session_init_compat)(fastd_context_t *ctx, const char *name, const uint8_t *secret, size_t length, bool initiator);
-	bool (*session_is_valid)(fastd_context_t *ctx, fastd_method_session_state_t *session);
-	bool (*session_is_initiator)(fastd_context_t *ctx, fastd_method_session_state_t *session);
-	bool (*session_want_refresh)(fastd_context_t *ctx, fastd_method_session_state_t *session);
-	void (*session_superseded)(fastd_context_t *ctx, fastd_method_session_state_t *session);
-	void (*session_free)(fastd_context_t *ctx, fastd_method_session_state_t *session);
-
-	bool (*encrypt)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
-	bool (*decrypt)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
-};
-
 union fastd_peer_address {
 	struct sockaddr sa;
 	struct sockaddr_in in;
@@ -210,7 +188,8 @@ struct fastd_config {
 	gid_t *groups;
 
 	const fastd_protocol_t *protocol;
-	fastd_string_stack_t *methods;
+	fastd_string_stack_t *method_list;
+	fastd_method_info_t *methods;
 
 	size_t max_overhead;
 	size_t min_encrypt_head_space;
@@ -335,8 +314,6 @@ void fastd_resolve_peer(fastd_context_t *ctx, fastd_peer_t *peer, fastd_remote_t
 int fastd_vsnprintf(const fastd_context_t *ctx, char *buffer, size_t size, const char *format, va_list ap);
 void fastd_logf(const fastd_context_t *ctx, fastd_loglevel_t level, const char *format, ...);
 
-const fastd_method_t* fastd_method_get_by_name(const char *name);
-
 void fastd_tuntap_open(fastd_context_t *ctx);
 fastd_buffer_t fastd_tuntap_read(fastd_context_t *ctx);
 void fastd_tuntap_write(fastd_context_t *ctx, fastd_buffer_t buffer);
diff --git a/src/handshake.c b/src/handshake.c
index 09a197a..4e53802 100644
--- a/src/handshake.c
+++ b/src/handshake.c
@@ -25,6 +25,7 @@
 
 
 #include "handshake.h"
+#include "method.h"
 #include "peer.h"
 #include <fastd_version.h>
 
@@ -59,17 +60,19 @@ static const char *const REPLY_TYPES[REPLY_MAX] = {
 
 
 static uint8_t* create_method_list(fastd_context_t *ctx, size_t *len) {
-	*len = strlen(ctx->conf->methods->str);
+	*len = 0;
 
-	fastd_string_stack_t *method;
-	for (method = ctx->conf->methods->next; method; method = method->next)
-		*len += strlen(method->str) + 1;
+	size_t i;
+	for (i = 0; ctx->conf->methods[i].name; i++)
+		*len += strlen(ctx->conf->methods[i].name) + 1;
+
+	uint8_t *ret = malloc(*len);
+	(*len)--;
 
-	uint8_t *ret = malloc(*len+1);
 	char *ptr = (char*)ret;
 
-	for (method = ctx->conf->methods; method; method = method->next)
-		ptr = stpcpy(ptr, method->str) + 1;
+	for (i = 0; ctx->conf->methods[i].name; i++)
+		ptr = stpcpy(ptr, ctx->conf->methods[i].name) + 1;
 
 	return ret;
 }
@@ -85,16 +88,6 @@ static inline bool record_equal(const char *str, const fastd_handshake_record_t
 	return string_equal(str, (const char*)record->data, record->length);
 }
 
-static const char* method_from_name(fastd_context_t *ctx, const char *name, size_t n) {
-	fastd_string_stack_t *method;
-	for (method = ctx->conf->methods; method; method = method->next) {
-		if (string_equal(method->str, name, n))
-			return method->str;
-	}
-
-	return NULL;
-}
-
 static fastd_string_stack_t* parse_string_list(const uint8_t *data, size_t len) {
 	const uint8_t *end = data+len;
 	fastd_string_stack_t *ret = NULL;
@@ -109,10 +102,10 @@ static fastd_string_stack_t* parse_string_list(const uint8_t *data, size_t len)
 	return ret;
 }
 
-static fastd_buffer_t new_handshake(fastd_context_t *ctx, uint8_t type, const char *method, bool with_method_list, size_t tail_space) {
+static fastd_buffer_t new_handshake(fastd_context_t *ctx, uint8_t type, const fastd_method_info_t *method, bool with_method_list, size_t tail_space) {
 	size_t version_len = strlen(FASTD_VERSION);
 	size_t protocol_len = strlen(ctx->conf->protocol->name);
-	size_t method_len = method ? strlen(method) : 0;
+	size_t method_len = method ? strlen(method->name) : 0;
 
 	size_t method_list_len = 0;
 	uint8_t *method_list = NULL;
@@ -141,7 +134,7 @@ static fastd_buffer_t new_handshake(fastd_context_t *ctx, uint8_t type, const ch
 	fastd_handshake_add(ctx, &buffer, RECORD_PROTOCOL_NAME, protocol_len, ctx->conf->protocol->name);
 
 	if (method && (!with_method_list || !ctx->conf->secure_handshakes))
-		fastd_handshake_add(ctx, &buffer, RECORD_METHOD_NAME, method_len, method);
+		fastd_handshake_add(ctx, &buffer, RECORD_METHOD_NAME, method_len, method->name);
 
 	if (with_method_list) {
 		fastd_handshake_add(ctx, &buffer, RECORD_METHOD_LIST, method_list_len, method_list);
@@ -155,7 +148,7 @@ fastd_buffer_t fastd_handshake_new_init(fastd_context_t *ctx, size_t tail_space)
 	return new_handshake(ctx, 1, NULL, !ctx->conf->secure_handshakes, tail_space);
 }
 
-fastd_buffer_t fastd_handshake_new_reply(fastd_context_t *ctx, const fastd_handshake_t *handshake, const char *method, bool with_method_list, size_t tail_space) {
+fastd_buffer_t fastd_handshake_new_reply(fastd_context_t *ctx, const fastd_handshake_t *handshake, const fastd_method_info_t *method, bool with_method_list, size_t tail_space) {
 	fastd_buffer_t buffer = new_handshake(ctx, handshake->type+1, method, with_method_list, tail_space);
 	fastd_handshake_add_uint8(ctx, &buffer, RECORD_REPLY_CODE, 0);
 	return buffer;
@@ -293,15 +286,23 @@ static inline bool check_records(fastd_context_t *ctx, fastd_socket_t *sock, con
 	return true;
 }
 
-static inline const char* get_method(fastd_context_t *ctx, const fastd_handshake_t *handshake) {
+static inline const fastd_method_info_t* get_method_by_name(fastd_context_t *ctx, const char *name, size_t n) {
+	char name0[n+1];
+	memcpy(name0, name, n);
+	name0[n] = 0;
+
+	return fastd_method_get_by_name(ctx, name0);
+}
+
+static inline const fastd_method_info_t* get_method(fastd_context_t *ctx, const fastd_handshake_t *handshake) {
 	if (handshake->records[RECORD_METHOD_LIST].data && handshake->records[RECORD_METHOD_LIST].length) {
 		fastd_string_stack_t *method_list = parse_string_list(handshake->records[RECORD_METHOD_LIST].data, handshake->records[RECORD_METHOD_LIST].length);
 
-		const char *method = NULL;
+		const fastd_method_info_t *method = NULL;
 
 		fastd_string_stack_t *method_name;
 		for (method_name = method_list; method_name; method_name = method_name->next) {
-			const char *cur_method = method_from_name(ctx, method_name->str, SIZE_MAX);
+			const fastd_method_info_t *cur_method = fastd_method_get_by_name(ctx, method_name->str);
 
 			if (cur_method)
 				method = cur_method;
@@ -315,12 +316,12 @@ static inline const char* get_method(fastd_context_t *ctx, const fastd_handshake
 	if (!handshake->records[RECORD_METHOD_NAME].data)
 		return NULL;
 
-	return method_from_name(ctx, (const char*)handshake->records[RECORD_METHOD_NAME].data, handshake->records[RECORD_METHOD_NAME].length);
+	return get_method_by_name(ctx, (const char*)handshake->records[RECORD_METHOD_NAME].data, handshake->records[RECORD_METHOD_NAME].length);
 }
 
 void fastd_handshake_handle(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, fastd_buffer_t buffer) {
 	char *peer_version = NULL;
-	const char *method = NULL;
+	const fastd_method_info_t *method = NULL;
 
 	fastd_handshake_t handshake = parse_tlvs(&buffer);
 
diff --git a/src/handshake.h b/src/handshake.h
index 4aff83c..196cc67 100644
--- a/src/handshake.h
+++ b/src/handshake.h
@@ -79,7 +79,7 @@ struct fastd_handshake {
 
 
 fastd_buffer_t fastd_handshake_new_init(fastd_context_t *ctx, size_t tail_space);
-fastd_buffer_t fastd_handshake_new_reply(fastd_context_t *ctx, const fastd_handshake_t *handshake, const char *method, bool with_method_list, size_t tail_space);
+fastd_buffer_t fastd_handshake_new_reply(fastd_context_t *ctx, const fastd_handshake_t *handshake, const fastd_method_info_t *method, bool with_method_list, size_t tail_space);
 
 void fastd_handshake_handle(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, fastd_buffer_t buffer);
 
diff --git a/src/method.h b/src/method.h
new file mode 100644
index 0000000..b56db14
--- /dev/null
+++ b/src/method.h
@@ -0,0 +1,77 @@
+/*
+  Copyright (c) 2012-2013, Matthias Schiffer <mschiffer@universe-factory.net>
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the documentation
+       and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+
+#ifndef _FASTD_METHOD_H_
+#define _FASTD_METHOD_H_
+
+#include "fastd.h"
+
+
+struct fastd_method_info {
+	const char *name;
+	const fastd_method_t *method;
+	fastd_method_context_t *ctx;
+};
+
+struct fastd_method {
+	size_t max_overhead;
+	size_t min_encrypt_head_space;
+	size_t min_decrypt_head_space;
+	size_t min_encrypt_tail_space;
+	size_t min_decrypt_tail_space;
+
+	bool (*create_by_name)(const char *name, fastd_method_context_t **method_ctx);
+	void (*destroy)(fastd_method_context_t *method_ctx);
+
+	size_t (*key_length)(fastd_context_t *ctx, const fastd_method_context_t *method_ctx);
+
+	fastd_method_session_state_t* (*session_init)(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, bool initiator);
+	fastd_method_session_state_t* (*session_init_compat)(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, size_t length, bool initiator);
+	bool (*session_is_valid)(fastd_context_t *ctx, fastd_method_session_state_t *session);
+	bool (*session_is_initiator)(fastd_context_t *ctx, fastd_method_session_state_t *session);
+	bool (*session_want_refresh)(fastd_context_t *ctx, fastd_method_session_state_t *session);
+	void (*session_superseded)(fastd_context_t *ctx, fastd_method_session_state_t *session);
+	void (*session_free)(fastd_context_t *ctx, fastd_method_session_state_t *session);
+
+	bool (*encrypt)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
+	bool (*decrypt)(fastd_context_t *ctx, fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in);
+};
+
+
+bool fastd_method_create_by_name(const char *name, const fastd_method_t **method, fastd_method_context_t **method_ctx);
+
+
+static inline const fastd_method_info_t* fastd_method_get_by_name(fastd_context_t *ctx, const char *name) {
+	size_t i;
+	for (i = 0; ctx->conf->methods[i].name; i++) {
+		if (!strcmp(ctx->conf->methods[i].name, name))
+			return &ctx->conf->methods[i];
+	}
+
+	return NULL;
+}
+
+#endif /* _FASTD_METHOD_H_ */
diff --git a/src/methods/cipher_test/cipher_test.c b/src/methods/cipher_test/cipher_test.c
index 067835e..fcf58e6 100644
--- a/src/methods/cipher_test/cipher_test.c
+++ b/src/methods/cipher_test/cipher_test.c
@@ -25,21 +25,27 @@
 
 
 #include "../../crypto.h"
+#include "../../method.h"
 #include "../common.h"
 
 
+struct fastd_method_context {
+	const fastd_cipher_info_t *cipher_info;
+};
+
 struct fastd_method_session_state {
 	fastd_method_common_t common;
 
-	const fastd_cipher_info_t *cipher_info;
+	const fastd_method_context_t *ctx;
 	const fastd_cipher_t *cipher;
 	fastd_cipher_state_t *cipher_state;
 };
 
 
-static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **info, const fastd_cipher_t **cipher) {
-	size_t len = strlen(name);
+static bool method_create_by_name(const char *name, fastd_method_context_t **method_ctx) {
+	fastd_method_context_t ctx;
 
+	size_t len = strlen(name);
 	if (len < 12)
 		return false;
 
@@ -50,46 +56,30 @@ static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_ciphe
 	memcpy(cipher_name, name, len-12);
 	cipher_name[len-12] = 0;
 
-	const fastd_cipher_info_t *cipher_info = NULL;
-
-	if (ctx) {
-		*cipher = fastd_cipher_get_by_name(ctx, cipher_name, &cipher_info);
-		if (!*cipher)
-			return false;
-	}
-	else {
-		cipher_info = fastd_cipher_info_get_by_name(cipher_name);
-		if (!cipher_info)
-			return false;
-	}
+	ctx.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+	if (!ctx.cipher_info)
+		return false;
 
-	if (info)
-		*info = cipher_info;
+	*method_ctx = malloc(sizeof(fastd_method_context_t));
+	**method_ctx = ctx;
 
 	return true;
 }
 
-
-static bool method_provides(const char *name) {
-	return cipher_get(NULL, name, NULL, NULL);
+static void method_destroy(fastd_method_context_t *method_ctx) {
+	free(method_ctx);
 }
 
-static size_t method_key_length(fastd_context_t *ctx, const char *name) {
-	const fastd_cipher_info_t *info;
-	if (!cipher_get(NULL, name, &info, NULL))
-		exit_bug(ctx, "cipher-test: can't get cipher key length");
-
-	return info->key_length;
+static size_t method_key_length(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx) {
+	return method_ctx->cipher_info->key_length;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, bool initiator) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	fastd_method_common_init(ctx, &session->common, initiator);
-
-	if (!cipher_get(ctx, name, &session->cipher_info, &session->cipher))
-		exit_bug(ctx, "cipher-test: can't instanciate cipher");
-
+	session->ctx = method_ctx;
+	session->cipher = fastd_cipher_get(ctx, session->ctx->cipher_info);
 	session->cipher_state = session->cipher->init(ctx, secret);
 
 	pr_warn(ctx, "using cipher-test method; this method must be used for testing and benchmarks only");
@@ -127,11 +117,12 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast
 	if (tail_len)
 		memset(in.data+in.len, 0, tail_len);
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	if (session->cipher_info->iv_length) {
-		memset(nonce, 0, session->cipher_info->iv_length);
-		memcpy(nonce, session->common.send_nonce, min_size_t(COMMON_NONCEBYTES, session->cipher_info->iv_length));
-		nonce[session->cipher_info->iv_length-1] = 1;
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	if (iv_length) {
+		memset(nonce, 0, iv_length);
+		memcpy(nonce, session->common.send_nonce, min_size_t(COMMON_NONCEBYTES, iv_length));
+		nonce[iv_length-1] = 1;
 	}
 
 	int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
@@ -170,11 +161,12 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 	if (common_nonce[COMMON_NONCEBYTES]) /* flags */
 		return false;
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	if (session->cipher_info->iv_length) {
-		memset(nonce, 0, session->cipher_info->iv_length);
-		memcpy(nonce, common_nonce, min_size_t(COMMON_NONCEBYTES, session->cipher_info->iv_length));
-		nonce[session->cipher_info->iv_length-1] = 1;
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	if (iv_length) {
+		memset(nonce, 0, iv_length);
+		memcpy(nonce, common_nonce, min_size_t(COMMON_NONCEBYTES, iv_length));
+		nonce[iv_length-1] = 1;
 	}
 
 	int64_t age;
@@ -209,15 +201,17 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_cipher_test = {
-	.provides = method_provides,
-
 	.max_overhead = COMMON_HEADBYTES,
 	.min_encrypt_head_space = 0,
 	.min_decrypt_head_space = 0,
 	.min_encrypt_tail_space = sizeof(fastd_block128_t)-1,
 	.min_decrypt_tail_space = sizeof(fastd_block128_t)-1,
 
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
 	.key_length = method_key_length,
+
 	.session_init = method_session_init,
 	.session_is_valid = method_session_is_valid,
 	.session_is_initiator = method_session_is_initiator,
diff --git a/src/methods/composed_gmac/composed_gmac.c b/src/methods/composed_gmac/composed_gmac.c
index 0705b7d..d1627ee 100644
--- a/src/methods/composed_gmac/composed_gmac.c
+++ b/src/methods/composed_gmac/composed_gmac.c
@@ -25,36 +25,43 @@
 
 
 #include "../../crypto.h"
+#include "../../method.h"
 #include "../common.h"
 
 
 static const fastd_block128_t ZERO_BLOCK = {};
 
+
+struct fastd_method_context {
+	const fastd_cipher_info_t *cipher_info;
+	const fastd_cipher_info_t *gmac_cipher_info;
+	const fastd_mac_info_t *ghash_info;
+};
+
 struct fastd_method_session_state {
 	fastd_method_common_t common;
 
-	const fastd_cipher_info_t *cipher_info;
+	const fastd_method_context_t *ctx;
+
 	const fastd_cipher_t *cipher;
 	fastd_cipher_state_t *cipher_state;
 
-	const fastd_cipher_info_t *gmac_cipher_info;
 	const fastd_cipher_t *gmac_cipher;
 	fastd_cipher_state_t *gmac_cipher_state;
 
-	const fastd_mac_info_t *ghash_info;
 	const fastd_mac_t *ghash;
 	fastd_mac_state_t *ghash_state;
 };
 
 
-static bool cipher_get(fastd_context_t *ctx, const char *name,
-		       const fastd_cipher_info_t **cipher_info, const fastd_cipher_t **cipher,
-		       const fastd_cipher_info_t **gmac_cipher_info, const fastd_cipher_t **gmac_cipher) {
-	if (!fastd_mac_info_get_by_name("ghash"))
+static bool method_create_by_name(const char *name, fastd_method_context_t **method_ctx) {
+	fastd_method_context_t ctx;
+
+	ctx.ghash_info = fastd_mac_info_get_by_name("ghash");
+	if (!ctx.ghash_info)
 		return false;
 
 	size_t len = strlen(name);
-
 	if (len < 5)
 		return false;
 
@@ -73,76 +80,52 @@ static bool cipher_get(fastd_context_t *ctx, const char *name,
 	*gmac_cipher_name = 0;
 	gmac_cipher_name++;
 
-	const fastd_cipher_info_t *info = NULL;
-	const fastd_cipher_info_t *gmac_info = NULL;
-
-	if (ctx) {
-		*cipher = fastd_cipher_get_by_name(ctx, cipher_name, &info);
-		*gmac_cipher = fastd_cipher_get_by_name(ctx, gmac_cipher_name, &gmac_info);
-		if (!(*cipher && *gmac_cipher))
-			return false;
-	}
-	else {
-		info = fastd_cipher_info_get_by_name(cipher_name);
-		gmac_info = fastd_cipher_info_get_by_name(gmac_cipher_name);
-		if (!(info && gmac_info))
-			return false;
-	}
-
-	if (cipher_info)
-		*cipher_info = info;
-
-	if (gmac_cipher_info)
-		*gmac_cipher_info = gmac_info;
-
-	return true;
-}
-
+	ctx.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+	if (!ctx.cipher_info)
+		return false;
 
-static bool method_provides(const char *name) {
-	const fastd_cipher_info_t *gmac_cipher_info;
+	if (ctx.cipher_info->iv_length && ctx.cipher_info->iv_length <= COMMON_NONCEBYTES)
+		return false;
 
-	if (!cipher_get(NULL, name, NULL, NULL, &gmac_cipher_info, NULL))
+	ctx.gmac_cipher_info = fastd_cipher_info_get_by_name(gmac_cipher_name);
+	if (!ctx.gmac_cipher_info)
 		return false;
 
-	if (gmac_cipher_info->iv_length <= COMMON_NONCEBYTES)
+	if (ctx.gmac_cipher_info->iv_length <= COMMON_NONCEBYTES)
 		return false;
 
+	*method_ctx = malloc(sizeof(fastd_method_context_t));
+	**method_ctx = ctx;
+
 	return true;
 }
 
-static size_t method_key_length(fastd_context_t *ctx, const char *name) {
-	const fastd_cipher_info_t *cipher_info;
-	const fastd_cipher_info_t *gmac_cipher_info;
+static void method_destroy(fastd_method_context_t *method_ctx) {
+	free(method_ctx);
+}
 
-	if (!cipher_get(NULL, name, &cipher_info, NULL, &gmac_cipher_info, NULL))
-		exit_bug(ctx, "composed-gmac: can't get cipher key length");
 
-	return cipher_info->key_length + gmac_cipher_info->key_length;
+static size_t method_key_length(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx) {
+	return method_ctx->cipher_info->key_length + method_ctx->gmac_cipher_info->key_length;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, bool initiator) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	fastd_method_common_init(ctx, &session->common, initiator);
+	session->ctx = method_ctx;
 
-	if (!cipher_get(ctx, name,
-			&session->cipher_info, &session->cipher,
-			&session->gmac_cipher_info, &session->gmac_cipher))
-		exit_bug(ctx, "composed-gmac: can't instanciate cipher");
-
+	session->cipher = fastd_cipher_get(ctx, session->ctx->cipher_info);
 	session->cipher_state = session->cipher->init(ctx, secret);
-	if (session->cipher_info->iv_length && session->cipher_info->iv_length <= COMMON_NONCEBYTES)
-		exit_bug(ctx, "composed-gmac: iv_length to small");
 
-	session->gmac_cipher_state = session->gmac_cipher->init(ctx, secret + session->cipher_info->key_length);
-	if (session->gmac_cipher_info->iv_length <= COMMON_NONCEBYTES)
-		exit_bug(ctx, "composed-gmac: GMAC cipher iv_length to small");
+	session->gmac_cipher = fastd_cipher_get(ctx, session->ctx->gmac_cipher_info);
+	session->gmac_cipher_state = session->gmac_cipher->init(ctx, secret + session->ctx->cipher_info->key_length);
 
 	fastd_block128_t H;
 
-	uint8_t zeroiv[session->gmac_cipher_info->iv_length];
-	memset(zeroiv, 0, session->gmac_cipher_info->iv_length);
+	size_t gmac_iv_length = session->ctx->gmac_cipher_info->iv_length;
+	uint8_t zeroiv[gmac_iv_length];
+	memset(zeroiv, 0, gmac_iv_length);
 
 	if (!session->gmac_cipher->crypt(ctx, session->gmac_cipher_state, &H, &ZERO_BLOCK, sizeof(fastd_block128_t), zeroiv)) {
 		session->cipher->free(ctx, session->cipher_state);
@@ -152,10 +135,7 @@ static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, c
 		return NULL;
 	}
 
-	session->ghash = fastd_mac_get_by_name(ctx, "ghash", &session->ghash_info);
-	if (!session->ghash)
-		exit_bug(ctx, "composed-gmac: can't instanciate ghash mac");
-
+	session->ghash = fastd_mac_get(ctx, session->ctx->ghash_info);
 	session->ghash_state = session->ghash->init(ctx, H.b);
 
 	return session;
@@ -209,19 +189,21 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast
 	fastd_block128_t *outblocks = out->data;
 	fastd_block128_t sig;
 
-	uint8_t gmac_nonce[session->gmac_cipher_info->iv_length];
-	memset(gmac_nonce, 0, session->gmac_cipher_info->iv_length);
+	size_t gmac_iv_length = session->ctx->gmac_cipher_info->iv_length;
+	uint8_t gmac_nonce[gmac_iv_length];
+	memset(gmac_nonce, 0, gmac_iv_length);
 	memcpy(gmac_nonce, session->common.send_nonce, COMMON_NONCEBYTES);
-	gmac_nonce[session->gmac_cipher_info->iv_length-1] = 1;
+	gmac_nonce[gmac_iv_length-1] = 1;
 
 	bool ok = session->gmac_cipher->crypt(ctx, session->gmac_cipher_state, outblocks, &ZERO_BLOCK, sizeof(fastd_block128_t), gmac_nonce);
 
 	if (ok) {
-		uint8_t nonce[session->cipher_info->iv_length];
-		if (session->cipher_info->iv_length) {
-			memset(nonce, 0, session->cipher_info->iv_length);
+		size_t iv_length = session->ctx->cipher_info->iv_length;
+		uint8_t nonce[iv_length];
+		if (iv_length) {
+			memset(nonce, 0, iv_length);
 			memcpy(nonce, session->common.send_nonce, COMMON_NONCEBYTES);
-			nonce[session->cipher_info->iv_length-1] = 1;
+			nonce[iv_length-1] = 1;
 		}
 
 		ok = session->cipher->crypt(ctx, session->cipher_state, outblocks+1, inblocks, n_blocks*sizeof(fastd_block128_t), nonce);
@@ -271,16 +253,18 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 	if (!fastd_method_is_nonce_valid(ctx, &session->common, common_nonce, &age))
 		return false;
 
-	uint8_t gmac_nonce[session->gmac_cipher_info->iv_length];
-	memset(gmac_nonce, 0, session->gmac_cipher_info->iv_length);
+	size_t gmac_iv_length = session->ctx->gmac_cipher_info->iv_length;
+	uint8_t gmac_nonce[gmac_iv_length];
+	memset(gmac_nonce, 0, gmac_iv_length);
 	memcpy(gmac_nonce, common_nonce, COMMON_NONCEBYTES);
-	gmac_nonce[session->gmac_cipher_info->iv_length-1] = 1;
+	gmac_nonce[gmac_iv_length-1] = 1;
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	if (session->cipher_info->iv_length) {
-		memset(nonce, 0, session->cipher_info->iv_length);
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	if (iv_length) {
+		memset(nonce, 0, iv_length);
 		memcpy(nonce, common_nonce, COMMON_NONCEBYTES);
-		nonce[session->cipher_info->iv_length-1] = 1;
+		nonce[iv_length-1] = 1;
 	}
 
 	fastd_buffer_push_head(ctx, &in, COMMON_HEADBYTES);
@@ -326,15 +310,17 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_composed_gmac = {
-	.provides = method_provides,
-
 	.max_overhead = COMMON_HEADBYTES + sizeof(fastd_block128_t),
 	.min_encrypt_head_space = 0,
 	.min_decrypt_head_space = 0,
 	.min_encrypt_tail_space = sizeof(fastd_block128_t)-1,
 	.min_decrypt_tail_space = 2*sizeof(fastd_block128_t)-1,
 
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
 	.key_length = method_key_length,
+
 	.session_init = method_session_init,
 	.session_is_valid = method_session_is_valid,
 	.session_is_initiator = method_session_is_initiator,
diff --git a/src/methods/generic_gcm/generic_gcm.c b/src/methods/generic_gcm/generic_gcm.c
index 52065eb..3490f8b 100644
--- a/src/methods/generic_gcm/generic_gcm.c
+++ b/src/methods/generic_gcm/generic_gcm.c
@@ -25,91 +25,82 @@
 
 
 #include "../../crypto.h"
+#include "../../method.h"
 #include "../common.h"
 
+struct fastd_method_context {
+	const fastd_cipher_info_t *cipher_info;
+	const fastd_mac_info_t *ghash_info;
+};
+
 
 struct fastd_method_session_state {
 	fastd_method_common_t common;
 
-	const fastd_cipher_info_t *cipher_info;
+	const fastd_method_context_t *ctx;
+
 	const fastd_cipher_t *cipher;
 	fastd_cipher_state_t *cipher_state;
 
-	const fastd_mac_info_t *ghash_info;
 	const fastd_mac_t *ghash;
 	fastd_mac_state_t *ghash_state;
 };
 
 
-static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **cipher_info, const fastd_cipher_t **cipher) {
-	if (!fastd_mac_info_get_by_name("ghash"))
+static bool method_create_by_name(const char *name, fastd_method_context_t **method_ctx) {
+	fastd_method_context_t ctx;
+
+	ctx.ghash_info = fastd_mac_info_get_by_name("ghash");
+	if (!ctx.ghash_info)
 		return false;
 
 	size_t len = strlen(name);
-
 	if (len < 4)
 		return false;
 
 	if (strcmp(name+len-4, "-gcm"))
 		return false;
 
-	char name_ctr[len+1];
-	memcpy(name_ctr, name, len-3);
-	strncpy(name_ctr+len-3, "ctr", 4);
+	char cipher_name[len+1];
+	memcpy(cipher_name, name, len-3);
+	strncpy(cipher_name+len-3, "ctr", 4);
 
-	const fastd_cipher_info_t *info = NULL;
-
-	if (ctx) {
-		*cipher = fastd_cipher_get_by_name(ctx, name_ctr, &info);
-		if (!*cipher)
-			return false;
-	}
-	else {
-		info = fastd_cipher_info_get_by_name(name_ctr);
-		if (!info)
-			return false;
-	}
+	ctx.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+	if (!ctx.cipher_info)
+		return false;
 
-	if (info->iv_length <= COMMON_NONCEBYTES)
+	if (ctx.cipher_info->iv_length <= COMMON_NONCEBYTES)
 		return false;
 
-	if (cipher_info)
-		*cipher_info = info;
+	*method_ctx = malloc(sizeof(fastd_method_context_t));
+	**method_ctx = ctx;
 
 	return true;
 }
 
-
-static bool method_provides(const char *name) {
-	return cipher_get(NULL, name, NULL, NULL);
+static void method_destroy(fastd_method_context_t *method_ctx) {
+	free(method_ctx);
 }
 
-static size_t method_key_length(fastd_context_t *ctx, const char *name) {
-	const fastd_cipher_info_t *cipher_info;
-	if (!cipher_get(NULL, name, &cipher_info, NULL))
-		exit_bug(ctx, "generic-gcm: can't get cipher key length");
-
-	return cipher_info->key_length;
+static size_t method_key_length(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx) {
+	return method_ctx->cipher_info->key_length;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, bool initiator) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	fastd_method_common_init(ctx, &session->common, initiator);
+	session->ctx = method_ctx;
 
-	if (!cipher_get(ctx, name, &session->cipher_info, &session->cipher))
-		exit_bug(ctx, "generic-gcm: can't instanciate cipher");
-
+	session->cipher = fastd_cipher_get(ctx, session->ctx->cipher_info);
 	session->cipher_state = session->cipher->init(ctx, secret);
 
 	static const fastd_block128_t zeroblock = {};
 	fastd_block128_t H;
 
-	if (session->cipher_info->iv_length <= COMMON_NONCEBYTES)
-		exit_bug(ctx, "generic-gcm: iv_length to small");
-
-	uint8_t zeroiv[session->cipher_info->iv_length];
-	memset(zeroiv, 0, session->cipher_info->iv_length);
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t zeroiv[iv_length];
+	memset(zeroiv, 0, iv_length);
 
 	if (!session->cipher->crypt(ctx, session->cipher_state, &H, &zeroblock, sizeof(fastd_block128_t), zeroiv)) {
 		session->cipher->free(ctx, session->cipher_state);
@@ -117,20 +108,17 @@ static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, c
 		return NULL;
 	}
 
-	session->ghash = fastd_mac_get_by_name(ctx, "ghash", &session->ghash_info);
-	if (!session->ghash)
-		exit_bug(ctx, "generic-gcm: can't instanciate ghash mac");
-
+	session->ghash = fastd_mac_get(ctx, session->ctx->ghash_info);
 	session->ghash_state = session->ghash->init(ctx, H.b);
 
 	return session;
 }
 
-static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const char *name, const uint8_t *secret, size_t length, bool initiator) {
+static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, size_t length, bool initiator) {
 	if (length < sizeof(fastd_block128_t))
 		exit_bug(ctx, "generic-gcm: tried to init with short secret");
 
-	return method_session_init(ctx, name, secret, initiator);
+	return method_session_init(ctx, method_ctx, secret, initiator);
 }
 
 static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) {
@@ -177,10 +165,11 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast
 	if (tail_len)
 		memset(in.data+in.len, 0, tail_len);
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	memset(nonce, 0, session->cipher_info->iv_length);
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	memset(nonce, 0, iv_length);
 	memcpy(nonce, session->common.send_nonce, COMMON_NONCEBYTES);
-	nonce[session->cipher_info->iv_length-1] = 1;
+	nonce[iv_length-1] = 1;
 
 	int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
 
@@ -230,10 +219,11 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 	if (((const uint8_t*)in.data)[COMMON_NONCEBYTES]) /* flags */
 		return false;
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	memset(nonce, 0, session->cipher_info->iv_length);
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	memset(nonce, 0, iv_length);
 	memcpy(nonce, in.data, COMMON_NONCEBYTES);
-	nonce[session->cipher_info->iv_length-1] = 1;
+	nonce[iv_length-1] = 1;
 
 	int64_t age;
 	if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce, &age))
@@ -279,15 +269,17 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_generic_gcm = {
-	.provides = method_provides,
-
 	.max_overhead = COMMON_HEADBYTES + sizeof(fastd_block128_t),
 	.min_encrypt_head_space = sizeof(fastd_block128_t),
 	.min_decrypt_head_space = 0,
 	.min_encrypt_tail_space = sizeof(fastd_block128_t)-1,
 	.min_decrypt_tail_space = 2*sizeof(fastd_block128_t)-1,
 
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
 	.key_length = method_key_length,
+
 	.session_init = method_session_init,
 	.session_init_compat = method_session_init_compat,
 	.session_is_valid = method_session_is_valid,
diff --git a/src/methods/generic_gmac/generic_gmac.c b/src/methods/generic_gmac/generic_gmac.c
index 4de7ad8..91b96cb 100644
--- a/src/methods/generic_gmac/generic_gmac.c
+++ b/src/methods/generic_gmac/generic_gmac.c
@@ -25,28 +25,37 @@
 
 
 #include "../../crypto.h"
+#include "../../method.h"
 #include "../common.h"
 
 
+struct fastd_method_context {
+	const fastd_cipher_info_t *cipher_info;
+	const fastd_mac_info_t *ghash_info;
+};
+
+
 struct fastd_method_session_state {
 	fastd_method_common_t common;
 
-	const fastd_cipher_info_t *cipher_info;
+	const fastd_method_context_t *ctx;
+
 	const fastd_cipher_t *cipher;
 	fastd_cipher_state_t *cipher_state;
 
-	const fastd_mac_info_t *ghash_info;
 	const fastd_mac_t *ghash;
 	fastd_mac_state_t *ghash_state;
 };
 
 
-static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **cipher_info, const fastd_cipher_t **cipher) {
-	if (!fastd_mac_info_get_by_name("ghash"))
+static bool method_create_by_name(const char *name, fastd_method_context_t **method_ctx) {
+	fastd_method_context_t ctx;
+
+	ctx.ghash_info = fastd_mac_info_get_by_name("ghash");
+	if (!ctx.ghash_info)
 		return false;
 
 	size_t len = strlen(name);
-
 	if (len < 5)
 		return false;
 
@@ -60,70 +69,42 @@ static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_ciphe
 	memcpy(cipher_name, name, len-5);
 	cipher_name[len-5] = 0;
 
-	const fastd_cipher_info_t *info = NULL;
-
-	if (ctx) {
-		*cipher = fastd_cipher_get_by_name(ctx, cipher_name, &info);
-		if (!*cipher)
-			return false;
-	}
-	else {
-		info = fastd_cipher_info_get_by_name(cipher_name);
-		if (!info)
-			return false;
-	}
+	ctx.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+	if (!ctx.cipher_info)
+		return false;
 
-	if (info->iv_length <= COMMON_NONCEBYTES)
+	if (ctx.cipher_info->iv_length <= COMMON_NONCEBYTES)
 		return false;
 
-	if (cipher_info)
-		*cipher_info = info;
+	*method_ctx = malloc(sizeof(fastd_method_context_t));
+	**method_ctx = ctx;
 
 	return true;
 }
 
-
-static bool method_provides(const char *name) {
-	return cipher_get(NULL, name, NULL, NULL);
+static void method_destroy(fastd_method_context_t *method_ctx) {
+	free(method_ctx);
 }
 
-static size_t method_key_length(fastd_context_t *ctx, const char *name) {
-	const fastd_cipher_info_t *cipher_info;
-	if (!cipher_get(NULL, name, &cipher_info, NULL))
-		exit_bug(ctx, "generic-gmac: can't get cipher key length");
-
-	return cipher_info->key_length + sizeof(fastd_block128_t);
+static size_t method_key_length(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx) {
+	return method_ctx->cipher_info->key_length + method_ctx->ghash_info->key_length;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, bool initiator) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	fastd_method_common_init(ctx, &session->common, initiator);
+	session->ctx = method_ctx;
 
-	if (!cipher_get(ctx, name, &session->cipher_info, &session->cipher))
-		exit_bug(ctx, "generic-gmac: can't instanciate cipher");
-
+	session->cipher = fastd_cipher_get(ctx, session->ctx->cipher_info);
 	session->cipher_state = session->cipher->init(ctx, secret);
 
-	if (session->cipher_info->iv_length <= COMMON_NONCEBYTES)
-		exit_bug(ctx, "generic-gmac: iv_length to small");
-
-	session->ghash = fastd_mac_get_by_name(ctx, "ghash", &session->ghash_info);
-	if (!session->ghash)
-		exit_bug(ctx, "generic-gmac: can't instanciate ghash mac");
-
-	session->ghash_state = session->ghash->init(ctx, secret + session->cipher_info->key_length);
+	session->ghash = fastd_mac_get(ctx, session->ctx->ghash_info);
+	session->ghash_state = session->ghash->init(ctx, secret + session->ctx->cipher_info->key_length);
 
 	return session;
 }
 
-static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const char *name, const uint8_t *secret, size_t length, bool initiator) {
-	if (length < sizeof(fastd_block128_t))
-		exit_bug(ctx, "generic-gmac: tried to init with short secret");
-
-	return method_session_init(ctx, name, secret, initiator);
-}
-
 static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) {
 	return (session && fastd_method_session_common_is_valid(ctx, &session->common));
 }
@@ -168,10 +149,11 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast
 	if (tail_len)
 		memset(in.data+in.len, 0, tail_len);
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	memset(nonce, 0, session->cipher_info->iv_length);
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	memset(nonce, 0, iv_length);
 	memcpy(nonce, session->common.send_nonce, COMMON_NONCEBYTES);
-	nonce[session->cipher_info->iv_length-1] = 1;
+	nonce[iv_length-1] = 1;
 
 	int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
 
@@ -221,10 +203,12 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 	if (((const uint8_t*)in.data)[COMMON_NONCEBYTES]) /* flags */
 		return false;
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	memset(nonce, 0, session->cipher_info->iv_length);
+
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	memset(nonce, 0, iv_length);
 	memcpy(nonce, in.data, COMMON_NONCEBYTES);
-	nonce[session->cipher_info->iv_length-1] = 1;
+	nonce[iv_length-1] = 1;
 
 	int64_t age;
 	if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce, &age))
@@ -270,17 +254,18 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_generic_gmac = {
-	.provides = method_provides,
-
 	.max_overhead = COMMON_HEADBYTES + sizeof(fastd_block128_t),
 	.min_encrypt_head_space = sizeof(fastd_block128_t),
 	.min_decrypt_head_space = 0,
 	.min_encrypt_tail_space = sizeof(fastd_block128_t)-1,
 	.min_decrypt_tail_space = 2*sizeof(fastd_block128_t)-1,
 
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
 	.key_length = method_key_length,
+
 	.session_init = method_session_init,
-	.session_init_compat = method_session_init_compat,
 	.session_is_valid = method_session_is_valid,
 	.session_is_initiator = method_session_is_initiator,
 	.session_want_refresh = method_session_want_refresh,
diff --git a/src/methods/generic_poly1305/generic_poly1305.c b/src/methods/generic_poly1305/generic_poly1305.c
index c40e70f..f84046e 100644
--- a/src/methods/generic_poly1305/generic_poly1305.c
+++ b/src/methods/generic_poly1305/generic_poly1305.c
@@ -25,6 +25,7 @@
 
 
 #include "../../crypto.h"
+#include "../../method.h"
 #include "../common.h"
 
 #include <crypto_onetimeauth_poly1305.h>
@@ -33,18 +34,23 @@
 #define AUTHBLOCKS 2
 
 
+struct fastd_method_context {
+	const fastd_cipher_info_t *cipher_info;
+};
+
 struct fastd_method_session_state {
 	fastd_method_common_t common;
 
-	const fastd_cipher_info_t *cipher_info;
+	const fastd_method_context_t *ctx;
 	const fastd_cipher_t *cipher;
 	fastd_cipher_state_t *cipher_state;
 };
 
 
-static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_info_t **cipher_info, const fastd_cipher_t **cipher) {
-	size_t len = strlen(name);
+static bool method_create_by_name(const char *name, fastd_method_context_t **method_ctx) {
+	fastd_method_context_t ctx;
 
+	size_t len = strlen(name);
 	if (len < 9)
 		return false;
 
@@ -55,54 +61,35 @@ static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_ciphe
 	memcpy(cipher_name, name, len-9);
 	cipher_name[len-9] = 0;
 
-	const fastd_cipher_info_t *info = NULL;
-
-	if (ctx) {
-		*cipher = fastd_cipher_get_by_name(ctx, cipher_name, &info);
-		if (!*cipher)
-			return false;
-	}
-	else {
-		info = fastd_cipher_info_get_by_name(cipher_name);
-		if (!info)
-			return false;
-	}
+	ctx.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+	if (!ctx.cipher_info)
+		return false;
 
-	if (info->iv_length <= COMMON_NONCEBYTES)
+	if (ctx.cipher_info->iv_length <= COMMON_NONCEBYTES)
 		return false;
 
-	if (cipher_info)
-		*cipher_info = info;
+	*method_ctx = malloc(sizeof(fastd_method_context_t));
+	**method_ctx = ctx;
 
 	return true;
 }
 
-
-static bool method_provides(const char *name) {
-	return cipher_get(NULL, name, NULL, NULL);
+static void method_destroy(fastd_method_context_t *method_ctx) {
+	free(method_ctx);
 }
 
-static size_t method_key_length(fastd_context_t *ctx, const char *name) {
-	const fastd_cipher_info_t *cipher_info;
-	if (!cipher_get(NULL, name, &cipher_info, NULL))
-		exit_bug(ctx, "generic-poly1305: can't get cipher key length");
-
-	return cipher_info->key_length;
+static size_t method_key_length(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx) {
+	return method_ctx->cipher_info->key_length;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, bool initiator) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	fastd_method_common_init(ctx, &session->common, initiator);
-
-	if (!cipher_get(ctx, name, &session->cipher_info, &session->cipher))
-		exit_bug(ctx, "generic-poly1305: can't instanciate cipher");
-
+	session->ctx = method_ctx;
+	session->cipher = fastd_cipher_get(ctx, session->ctx->cipher_info);
 	session->cipher_state = session->cipher->init(ctx, secret);
 
-	if (session->cipher_info->iv_length <= COMMON_NONCEBYTES)
-		exit_bug(ctx, "generic-poly1305: iv_length to small");
-
 	return session;
 }
 
@@ -139,10 +126,11 @@ static bool method_encrypt(fastd_context_t *ctx, fastd_peer_t *peer UNUSED, fast
 	if (tail_len)
 		memset(in.data+in.len, 0, tail_len);
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	memset(nonce, 0, session->cipher_info->iv_length);
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	memset(nonce, 0, iv_length);
 	memcpy(nonce, session->common.send_nonce, COMMON_NONCEBYTES);
-	nonce[session->cipher_info->iv_length-1] = 1;
+	nonce[iv_length-1] = 1;
 
 	int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
 
@@ -186,10 +174,11 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 	if (((const uint8_t*)in.data)[COMMON_NONCEBYTES]) /* flags */
 		return false;
 
-	uint8_t nonce[session->cipher_info->iv_length];
-	memset(nonce, 0, session->cipher_info->iv_length);
+	size_t iv_length = session->ctx->cipher_info->iv_length;
+	uint8_t nonce[iv_length];
+	memset(nonce, 0, iv_length);
 	memcpy(nonce, in.data, COMMON_NONCEBYTES);
-	nonce[session->cipher_info->iv_length-1] = 1;
+	nonce[iv_length-1] = 1;
 
 	int64_t age;
 	if (!fastd_method_is_nonce_valid(ctx, &session->common, nonce, &age))
@@ -245,15 +234,17 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_generic_poly1305 = {
-	.provides = method_provides,
-
 	.max_overhead = COMMON_HEADBYTES + crypto_onetimeauth_poly1305_BYTES,
 	.min_encrypt_head_space = AUTHBLOCKS*sizeof(fastd_block128_t),
 	.min_decrypt_head_space = AUTHBLOCKS*sizeof(fastd_block128_t) - crypto_onetimeauth_poly1305_BYTES,
 	.min_encrypt_tail_space = sizeof(fastd_block128_t)-1,
 	.min_decrypt_tail_space = sizeof(fastd_block128_t)-1,
 
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
 	.key_length = method_key_length,
+
 	.session_init = method_session_init,
 	.session_is_valid = method_session_is_valid,
 	.session_is_initiator = method_session_is_initiator,
diff --git a/src/methods/methods.c.in b/src/methods/methods.c.in
index 2a8d9fb..a2c7963 100644
--- a/src/methods/methods.c.in
+++ b/src/methods/methods.c.in
@@ -24,7 +24,7 @@
 */
 
 
-#include <src/fastd.h>
+#include <src/method.h>
 
 
 @METHOD_DEFINITIONS@
@@ -33,12 +33,14 @@ static const fastd_method_t *const methods[] = { @METHOD_LIST@
 };
 
 
-const fastd_method_t* fastd_method_get_by_name(const char *name) {
+bool fastd_method_create_by_name(const char *name, const fastd_method_t **method, fastd_method_context_t **method_ctx) {
 	size_t i;
 	for (i = 0; i < array_size(methods); i++) {
-		if (methods[i]->provides(name))
-			return methods[i];
+		if (methods[i]->create_by_name(name, method_ctx)) {
+			*method = methods[i];
+			return true;
+		}
 	}
 
-	return NULL;
+	return false;
 }
diff --git a/src/methods/null/null.c b/src/methods/null/null.c
index 3f23866..f4784c8 100644
--- a/src/methods/null/null.c
+++ b/src/methods/null/null.c
@@ -24,7 +24,7 @@
 */
 
 
-#include "../../fastd.h"
+#include "../../method.h"
 
 
 struct fastd_method_session_state {
@@ -33,15 +33,18 @@ struct fastd_method_session_state {
 };
 
 
-static bool method_provides(const char *name) {
+static bool method_create_by_name(const char *name, fastd_method_context_t **method_ctx UNUSED) {
 	return !strcmp(name, "null");
 }
 
-static size_t method_key_length(fastd_context_t *ctx UNUSED, const char *name UNUSED) {
+static void method_destroy(fastd_method_context_t *method_ctx UNUSED) {
+}
+
+static size_t method_key_length(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx UNUSED) {
 	return 0;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx UNUSED, const char *name UNUSED, const uint8_t *secret UNUSED, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx UNUSED, const uint8_t *secret UNUSED, bool initiator) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	session->valid = true;
@@ -50,8 +53,8 @@ static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx UN
 	return session;
 }
 
-static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const char *name, const uint8_t *secret, size_t length UNUSED, bool initiator) {
-	return method_session_init(ctx, name, secret, initiator);
+static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, size_t length UNUSED, bool initiator) {
+	return method_session_init(ctx, method_ctx, secret, initiator);
 }
 
 static bool method_session_is_valid(fastd_context_t *ctx UNUSED, fastd_method_session_state_t *session) {
@@ -80,15 +83,17 @@ static bool method_passthrough(fastd_context_t *ctx UNUSED, fastd_peer_t *peer U
 }
 
 const fastd_method_t fastd_method_null = {
-	.provides = method_provides,
-
 	.max_overhead = 0,
 	.min_encrypt_head_space = 0,
 	.min_decrypt_head_space = 0,
 	.min_encrypt_tail_space = 0,
 	.min_decrypt_tail_space = 0,
 
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
 	.key_length = method_key_length,
+
 	.session_init = method_session_init,
 	.session_init_compat = method_session_init_compat,
 	.session_is_valid = method_session_is_valid,
diff --git a/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c b/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c
index c6e22fb..88a0525 100644
--- a/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c
+++ b/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c
@@ -24,7 +24,7 @@
 */
 
 
-#include "../../fastd.h"
+#include "../../method.h"
 #include "../common.h"
 
 #include <crypto_secretbox_xsalsa20poly1305.h>
@@ -37,15 +37,18 @@ struct fastd_method_session_state {
 };
 
 
-static bool method_provides(const char *name) {
+static bool method_create_by_name(const char *name, fastd_method_context_t **method_ctx UNUSED) {
 	return !strcmp(name, "xsalsa20-poly1305");
 }
 
-static size_t method_key_length(fastd_context_t *ctx UNUSED, const char *name UNUSED) {
+static void method_destroy(fastd_method_context_t *method_ctx UNUSED) {
+}
+
+static size_t method_key_length(fastd_context_t *ctx UNUSED, const fastd_method_context_t *method_ctx UNUSED) {
 	return crypto_secretbox_xsalsa20poly1305_KEYBYTES;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name UNUSED, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const fastd_method_context_t *method_ctx UNUSED, const uint8_t *secret, bool initiator) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	fastd_method_common_init(ctx, &session->common, initiator);
@@ -55,11 +58,11 @@ static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, c
 	return session;
 }
 
-static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const char *name, const uint8_t *secret, size_t length, bool initiator) {
+static fastd_method_session_state_t* method_session_init_compat(fastd_context_t *ctx, const fastd_method_context_t *method_ctx, const uint8_t *secret, size_t length, bool initiator) {
 	if (length < crypto_secretbox_xsalsa20poly1305_KEYBYTES)
 		exit_bug(ctx, "xsalsa20-poly1305: tried to init with short secret");
 
-	return method_session_init(ctx, name, secret, initiator);
+	return method_session_init(ctx, method_ctx, secret, initiator);
 }
 
 static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) {
@@ -153,7 +156,6 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_xsalsa20_poly1305 = {
-	.provides = method_provides,
 
 	.max_overhead = COMMON_HEADBYTES + crypto_secretbox_xsalsa20poly1305_ZEROBYTES - crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES,
 	.min_encrypt_head_space = crypto_secretbox_xsalsa20poly1305_ZEROBYTES,
@@ -161,7 +163,11 @@ const fastd_method_t fastd_method_xsalsa20_poly1305 = {
 	.min_encrypt_tail_space = 0,
 	.min_decrypt_tail_space = 0,
 
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
 	.key_length = method_key_length,
+
 	.session_init = method_session_init,
 	.session_init_compat = method_session_init_compat,
 	.session_is_valid = method_session_is_valid,
diff --git a/src/options.c b/src/options.c
index f7dd88f..c86717b 100644
--- a/src/options.c
+++ b/src/options.c
@@ -251,8 +251,7 @@ static void option_protocol(fastd_context_t *ctx, fastd_config_t *conf, const ch
 }
 
 static void option_method(fastd_context_t *ctx, fastd_config_t *conf, const char *arg) {
-	if (!fastd_config_method(ctx, conf, arg))
-		exit_error(ctx, "unsupported method `%s'", arg);
+	fastd_config_method(ctx, conf, arg);
 }
 
 static void option_forward(fastd_context_t *ctx UNUSED, fastd_config_t *conf) {
diff --git a/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c
index 743b0d1..a8de436 100644
--- a/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c
+++ b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c
@@ -41,7 +41,7 @@ static inline bool read_key(uint8_t key[32], const char *hexkey) {
 static inline void check_session_refresh(fastd_context_t *ctx, fastd_peer_t *peer) {
 	protocol_session_t *session = &peer->protocol_state->session;
 
-	if (!session->refreshing && session->method->session_want_refresh(ctx, session->method_state)) {
+	if (!session->refreshing && session->method->method->session_want_refresh(ctx, session->method_state)) {
 		pr_verbose(ctx, "refreshing session with %P", peer);
 		session->handshakes_cleaned = true;
 		session->refreshing = true;
@@ -104,17 +104,17 @@ static void protocol_handle_recv(fastd_context_t *ctx, fastd_peer_t *peer, fastd
 	bool ok = false;
 
 	if (is_session_valid(ctx, &peer->protocol_state->old_session)) {
-		if (peer->protocol_state->old_session.method->decrypt(ctx, peer, peer->protocol_state->old_session.method_state, &recv_buffer, buffer))
+		if (peer->protocol_state->old_session.method->method->decrypt(ctx, peer, peer->protocol_state->old_session.method_state, &recv_buffer, buffer))
 			ok = true;
 	}
 
 	if (!ok) {
-		if (peer->protocol_state->session.method->decrypt(ctx, peer, peer->protocol_state->session.method_state, &recv_buffer, buffer)) {
+		if (peer->protocol_state->session.method->method->decrypt(ctx, peer, peer->protocol_state->session.method_state, &recv_buffer, buffer)) {
 			ok = true;
 
 			if (peer->protocol_state->old_session.method) {
 				pr_debug(ctx, "invalidating old session with %P", peer);
-				peer->protocol_state->old_session.method->session_free(ctx, peer->protocol_state->old_session.method_state);
+				peer->protocol_state->old_session.method->method->session_free(ctx, peer->protocol_state->old_session.method_state);
 				peer->protocol_state->old_session = (protocol_session_t){};
 			}
 
@@ -123,7 +123,7 @@ static void protocol_handle_recv(fastd_context_t *ctx, fastd_peer_t *peer, fastd
 				fastd_peer_unschedule_handshake(ctx, peer);
 				peer->protocol_state->session.handshakes_cleaned = true;
 
-				if (peer->protocol_state->session.method->session_is_initiator(ctx, peer->protocol_state->session.method_state))
+				if (peer->protocol_state->session.method->method->session_is_initiator(ctx, peer->protocol_state->session.method_state))
 					fastd_protocol_ec25519_fhmqvc_send_empty(ctx, peer, &peer->protocol_state->session);
 			}
 
@@ -153,7 +153,7 @@ static void session_send(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_
 	size_t stat_size = buffer.len;
 
 	fastd_buffer_t send_buffer;
-	if (!session->method->encrypt(ctx, peer, session->method_state, &send_buffer, buffer)) {
+	if (!session->method->method->encrypt(ctx, peer, session->method_state, &send_buffer, buffer)) {
 		fastd_buffer_free(buffer);
 		pr_error(ctx, "failed to encrypt packet for %P", peer);
 		return;
@@ -171,7 +171,7 @@ static void protocol_send(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer
 
 	check_session_refresh(ctx, peer);
 
-	if (peer->protocol_state->session.method->session_is_initiator(ctx, peer->protocol_state->session.method_state) && is_session_valid(ctx, &peer->protocol_state->old_session)) {
+	if (peer->protocol_state->session.method->method->session_is_initiator(ctx, peer->protocol_state->session.method_state) && is_session_valid(ctx, &peer->protocol_state->old_session)) {
 		pr_debug2(ctx, "sending packet for old session to %P", peer);
 		session_send(ctx, peer, buffer, &peer->protocol_state->old_session);
 	}
@@ -181,7 +181,7 @@ static void protocol_send(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer
 }
 
 void fastd_protocol_ec25519_fhmqvc_send_empty(fastd_context_t *ctx, fastd_peer_t *peer, protocol_session_t *session) {
-	session_send(ctx, peer, fastd_buffer_alloc(ctx, 0, alignto(session->method->min_encrypt_head_space, 8), session->method->min_encrypt_tail_space), session);
+	session_send(ctx, peer, fastd_buffer_alloc(ctx, 0, alignto(session->method->method->min_encrypt_head_space, 8), session->method->method->min_encrypt_tail_space), session);
 }
 
 const fastd_protocol_t fastd_protocol_ec25519_fhmqvc = {
diff --git a/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.h b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.h
index 608276f..638117d 100644
--- a/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.h
+++ b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.h
@@ -28,6 +28,7 @@
 #define _FASTD_PROTOCOL_EC25519_FHMQVC_H_
 
 #include "../../fastd.h"
+#include "../../method.h"
 #include "../../peer.h"
 #include "../../sha256.h"
 
@@ -59,7 +60,7 @@ typedef struct protocol_session {
 	bool handshakes_cleaned;
 	bool refreshing;
 
-	const fastd_method_t *method;
+	const fastd_method_info_t *method;
 	fastd_method_session_state_t *method_state;
 } protocol_session_t;
 
@@ -87,7 +88,7 @@ void fastd_protocol_ec25519_fhmqvc_reset_peer_state(fastd_context_t *ctx, fastd_
 void fastd_protocol_ec25519_fhmqvc_free_peer_state(fastd_context_t *ctx, fastd_peer_t *peer);
 
 void fastd_protocol_ec25519_fhmqvc_handshake_init(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer);
-void fastd_protocol_ec25519_fhmqvc_handshake_handle(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const fastd_handshake_t *handshake, const char *method);
+void fastd_protocol_ec25519_fhmqvc_handshake_handle(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const fastd_handshake_t *handshake, const fastd_method_info_t *method);
 
 void fastd_protocol_ec25519_fhmqvc_send_empty(fastd_context_t *ctx, fastd_peer_t *peer, protocol_session_t *session);
 
@@ -105,7 +106,7 @@ static inline void hexdump(char out[65], const unsigned char d[32]) {
 
 
 static inline bool is_session_valid(fastd_context_t *ctx, const protocol_session_t *session) {
-	return (session->method && session->method->session_is_valid(ctx, session->method_state));
+	return (session->method && session->method->method->session_is_valid(ctx, session->method_state));
 }
 
 #endif /* _FASTD_PROTOCOL_EC25519_FHMQVC_H_ */
diff --git a/src/protocols/ec25519_fhmqvc/handshake.c b/src/protocols/ec25519_fhmqvc/handshake.c
index c359fb1..0225513 100644
--- a/src/protocols/ec25519_fhmqvc/handshake.c
+++ b/src/protocols/ec25519_fhmqvc/handshake.c
@@ -68,46 +68,46 @@ static void derive_key(fastd_sha256_t *out, size_t blocks, const uint32_t *salt,
 	fastd_hkdf_sha256_expand(out, blocks, &prk, info, sizeof(info));
 }
 
-static inline void supersede_session(fastd_context_t *ctx, fastd_peer_t *peer, const fastd_method_t *method) {
+static inline void supersede_session(fastd_context_t *ctx, fastd_peer_t *peer, const fastd_method_info_t *method) {
 	if (is_session_valid(ctx, &peer->protocol_state->session) && !is_session_valid(ctx, &peer->protocol_state->old_session)) {
 		if (peer->protocol_state->old_session.method)
-			peer->protocol_state->old_session.method->session_free(ctx, peer->protocol_state->old_session.method_state);
+			peer->protocol_state->old_session.method->method->session_free(ctx, peer->protocol_state->old_session.method_state);
 		peer->protocol_state->old_session = peer->protocol_state->session;
 	}
 	else {
 		if (peer->protocol_state->session.method)
-			peer->protocol_state->session.method->session_free(ctx, peer->protocol_state->session.method_state);
+			peer->protocol_state->session.method->method->session_free(ctx, peer->protocol_state->session.method_state);
 	}
 
 	if (peer->protocol_state->old_session.method) {
 		if (peer->protocol_state->old_session.method != method) {
 			pr_debug(ctx, "method of %P has changed, terminating old session", peer);
-			peer->protocol_state->old_session.method->session_free(ctx, peer->protocol_state->old_session.method_state);
+			peer->protocol_state->old_session.method->method->session_free(ctx, peer->protocol_state->old_session.method_state);
 			peer->protocol_state->old_session = (protocol_session_t){};
 		}
 		else {
-			peer->protocol_state->old_session.method->session_superseded(ctx, peer->protocol_state->old_session.method_state);
+			peer->protocol_state->old_session.method->method->session_superseded(ctx, peer->protocol_state->old_session.method_state);
 		}
 	}
 }
 
-static inline bool new_session(fastd_context_t *ctx, fastd_peer_t *peer, const char *method_name, const fastd_method_t *method, bool initiator,
+static inline bool new_session(fastd_context_t *ctx, fastd_peer_t *peer, const fastd_method_info_t *method, bool initiator,
 			       const aligned_int256_t *A, const aligned_int256_t *B, const aligned_int256_t *X, const aligned_int256_t *Y,
 			       const aligned_int256_t *sigma, const uint32_t *salt, uint64_t serial) {
 
 	supersede_session(ctx, peer, method);
 
 	if (salt) {
-		size_t blocks = block_count(method->key_length(ctx, method_name), sizeof(fastd_sha256_t));
+		size_t blocks = block_count(method->method->key_length(ctx, method->ctx), sizeof(fastd_sha256_t));
 		fastd_sha256_t secret[blocks];
-		derive_key(secret, blocks, salt, method_name, A, B, X, Y, sigma);
+		derive_key(secret, blocks, salt, method->name, A, B, X, Y, sigma);
 
-		peer->protocol_state->session.method_state = method->session_init(ctx, method_name, (const uint8_t*)secret, initiator);
+		peer->protocol_state->session.method_state = method->method->session_init(ctx, method->ctx, (const uint8_t*)secret, initiator);
 	}
 	else {
 		fastd_sha256_t hash;
 		fastd_sha256_blocks(&hash, X->u32, Y->u32, A->u32, B->u32, sigma->u32, NULL);
-		peer->protocol_state->session.method_state = method->session_init_compat(ctx, method_name, hash.b, HASHBYTES, initiator);
+		peer->protocol_state->session.method_state = method->method->session_init_compat(ctx, method->ctx, hash.b, HASHBYTES, initiator);
 	}
 
 	if (!peer->protocol_state->session.method_state)
@@ -122,7 +122,7 @@ static inline bool new_session(fastd_context_t *ctx, fastd_peer_t *peer, const c
 	return true;
 }
 
-static bool establish(fastd_context_t *ctx, fastd_peer_t *peer, const char *method_name, fastd_socket_t *sock,
+static bool establish(fastd_context_t *ctx, fastd_peer_t *peer, const fastd_method_info_t *method, fastd_socket_t *sock,
 		      const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, bool initiator,
 		      const aligned_int256_t *A, const aligned_int256_t *B, const aligned_int256_t *X, const aligned_int256_t *Y,
 		      const aligned_int256_t *sigma, const uint32_t *salt, uint64_t serial) {
@@ -131,9 +131,8 @@ static bool establish(fastd_context_t *ctx, fastd_peer_t *peer, const char *meth
 		return false;
 	}
 
-	const fastd_method_t *method = fastd_method_get_by_name(method_name);
-	if (!salt && !method->session_init_compat) {
-		pr_warn(ctx, "can't establish session with %P[%I] (method without compat support)", peer, remote_addr);
+	if (!salt && !method->method->session_init_compat) {
+		pr_warn(ctx, "can't establish compat session with %P[%I] (method without compat support)", peer, remote_addr);
 		return false;
 	}
 
@@ -145,8 +144,8 @@ static bool establish(fastd_context_t *ctx, fastd_peer_t *peer, const char *meth
 		return false;
 	}
 
-	if (!new_session(ctx, peer, method_name, method, initiator, A, B, X, Y, sigma, salt, serial)) {
-		pr_error(ctx, "failed to initialize method session for %P (method `%s'%s)", peer, method_name, salt ? "" : " (compat mode)");
+	if (!new_session(ctx, peer, method, initiator, A, B, X, Y, sigma, salt, serial)) {
+		pr_error(ctx, "failed to initialize method session for %P (method `%s'%s)", peer, method->name, salt ? "" : " (compat mode)");
 		fastd_peer_reset(ctx, peer);
 		return false;
 	}
@@ -154,7 +153,7 @@ static bool establish(fastd_context_t *ctx, fastd_peer_t *peer, const char *meth
 	fastd_peer_seen(ctx, peer);
 	fastd_peer_set_established(ctx, peer);
 
-	pr_verbose(ctx, "new session with %P established using method `%s'%s.", peer, method_name, salt ? "" : " (compat mode)");
+	pr_verbose(ctx, "new session with %P established using method `%s'%s.", peer, method->name, salt ? "" : " (compat mode)");
 
 	if (initiator)
 		fastd_peer_schedule_handshake_default(ctx, peer);
@@ -271,7 +270,7 @@ static void clear_shared_handshake_key(fastd_context_t *ctx UNUSED, const fastd_
 }
 
 static void respond_handshake(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer,
-			      const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key, const fastd_handshake_t *handshake, const char *method) {
+			      const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key, const fastd_handshake_t *handshake, const fastd_method_info_t *method) {
 	pr_debug(ctx, "responding handshake with %P[%I]...", peer, remote_addr);
 
 	if (!update_shared_handshake_key(ctx, peer, handshake_key, peer_handshake_key))
@@ -299,7 +298,7 @@ static void respond_handshake(fastd_context_t *ctx, const fastd_socket_t *sock,
 }
 
 static void finish_handshake(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key,
-			     const fastd_handshake_t *handshake, const char *method) {
+			     const fastd_handshake_t *handshake, const fastd_method_info_t *method) {
 	pr_debug(ctx, "finishing handshake with %P[%I]...", peer, remote_addr);
 
 	bool compat = !secure_handshake(handshake);
@@ -361,7 +360,7 @@ static void finish_handshake(fastd_context_t *ctx, fastd_socket_t *sock, const f
 
 static void handle_finish_handshake(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr,
 				    fastd_peer_t *peer, const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key,
-				    const fastd_handshake_t *handshake, const char *method) {
+				    const fastd_handshake_t *handshake, const fastd_method_info_t *method) {
 	pr_debug(ctx, "handling handshake finish with %P[%I]...", peer, remote_addr);
 
 	bool compat = !secure_handshake(handshake);
@@ -538,7 +537,7 @@ void fastd_protocol_ec25519_fhmqvc_handshake_init(fastd_context_t *ctx, const fa
 	fastd_send_handshake(ctx, sock, local_addr, remote_addr, peer, buffer);
 }
 
-void fastd_protocol_ec25519_fhmqvc_handshake_handle(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const fastd_handshake_t *handshake, const char *method) {
+void fastd_protocol_ec25519_fhmqvc_handshake_handle(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const fastd_handshake_t *handshake, const fastd_method_info_t *method) {
 	bool temporary_added = false;
 
 	fastd_protocol_ec25519_fhmqvc_maintenance(ctx);
diff --git a/src/protocols/ec25519_fhmqvc/state.c b/src/protocols/ec25519_fhmqvc/state.c
index 727763a..f27fcc6 100644
--- a/src/protocols/ec25519_fhmqvc/state.c
+++ b/src/protocols/ec25519_fhmqvc/state.c
@@ -77,7 +77,7 @@ void fastd_protocol_ec25519_fhmqvc_init_peer_state(fastd_context_t *ctx, fastd_p
 
 static void reset_session(fastd_context_t *ctx, protocol_session_t *session) {
 	if (session->method)
-		session->method->session_free(ctx, session->method_state);
+		session->method->method->session_free(ctx, session->method_state);
 	secure_memzero(session, sizeof(protocol_session_t));
 }
 
diff --git a/src/types.h b/src/types.h
index fc26f3a..664518d 100644
--- a/src/types.h
+++ b/src/types.h
@@ -113,6 +113,7 @@ typedef struct fastd_config fastd_config_t;
 typedef struct fastd_context fastd_context_t;
 
 typedef struct fastd_protocol fastd_protocol_t;
+typedef struct fastd_method_info fastd_method_info_t;
 typedef struct fastd_method fastd_method_t;
 
 typedef struct fastd_cipher_info fastd_cipher_info_t;
@@ -141,6 +142,7 @@ typedef struct fastd_protocol_state fastd_protocol_state_t;
 typedef struct fastd_protocol_peer_config fastd_protocol_peer_config_t;
 typedef struct fastd_protocol_peer_state fastd_protocol_peer_state_t;
 
+typedef struct fastd_method_context fastd_method_context_t;
 typedef struct fastd_method_session_state fastd_method_session_state_t;
 
 typedef struct fastd_cipher_state fastd_cipher_state_t;