Allow flexible specification of methods provided by an implementation

7 files changed, 35 insertions, 23 deletions

diff --git a/src/config.c b/src/config.c
index 8cf0dcb..aa5ea59 100644
--- a/src/config.c
+++ b/src/config.c
@@ -95,7 +95,7 @@ bool fastd_config_protocol(fastd_context_t *ctx UNUSED, fastd_config_t *conf, co
 }
 
 bool fastd_config_method(fastd_context_t *ctx, fastd_config_t *conf, const char *name) {
-	if (!fastd_method_get_by_name(name))
+	if (!fastd_method_get_by_name(ctx, name))
 		return false;
 
 	fastd_string_stack_t **method;
@@ -508,7 +508,7 @@ static void configure_method_parameters(fastd_context_t *ctx, fastd_config_t *co
 
 	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);
+		const fastd_method_t *method = fastd_method_get_by_name(ctx, method_name->str);
 
 		conf->max_packet_size = max_size_t(conf->max_packet_size, method->max_packet_size(ctx));
 		conf->min_encrypt_head_space = max_size_t(conf->min_encrypt_head_space, method->min_encrypt_head_space(ctx));
diff --git a/src/fastd.h b/src/fastd.h
index 2607322..5ace535 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -79,7 +79,7 @@ struct fastd_protocol {
 };
 
 struct fastd_method {
-	const char *name;
+	bool (*provides)(fastd_context_t *ctx, const char *name);
 
 	size_t (*max_packet_size)(fastd_context_t *ctx);
 	size_t (*min_encrypt_head_space)(fastd_context_t *ctx);
@@ -88,8 +88,8 @@ struct fastd_method {
 	size_t (*min_decrypt_tail_space)(fastd_context_t *ctx);
 
 	size_t (*key_length)(fastd_context_t *ctx);
-	fastd_method_session_state_t* (*session_init)(fastd_context_t *ctx, const uint8_t *secret, bool initiator);
-	fastd_method_session_state_t* (*session_init_compat)(fastd_context_t *ctx, const uint8_t *secret, size_t length, bool initiator);
+	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);
@@ -359,7 +359,7 @@ void fastd_logf(const fastd_context_t *ctx, fastd_loglevel_t level, const char *
 void fastd_add_peer_dir(fastd_context_t *ctx, fastd_config_t *conf, const char *dir);
 bool fastd_read_config(fastd_context_t *ctx, fastd_config_t *conf, const char *filename, bool peer_config, int depth);
 
-const fastd_method_t* fastd_method_get_by_name(const char *name);
+const fastd_method_t* fastd_method_get_by_name(fastd_context_t *ctx, const char *name);
 
 const fastd_cipher_t** fastd_cipher_config_alloc(void);
 void fastd_cipher_config_free(const fastd_cipher_t **cipher_conf);
diff --git a/src/methods/aes128_gcm/aes128_gcm.c b/src/methods/aes128_gcm/aes128_gcm.c
index 59e6914..8a6325e 100644
--- a/src/methods/aes128_gcm/aes128_gcm.c
+++ b/src/methods/aes128_gcm/aes128_gcm.c
@@ -40,6 +40,10 @@ struct fastd_method_session_state {
 };
 
 
+static bool method_provides(fastd_context_t *ctx UNUSED, const char *name) {
+	return !strcmp(name, "aes128-gcm");
+}
+
 static size_t method_max_packet_size(fastd_context_t *ctx) {
 	return (fastd_max_packet_size(ctx) + COMMON_NONCEBYTES + sizeof(fastd_block128_t));
 }
@@ -66,7 +70,7 @@ static size_t method_key_length(fastd_context_t *ctx UNUSED) {
 	return sizeof(fastd_block128_t);
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name 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);
@@ -87,11 +91,11 @@ 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 uint8_t *secret, size_t length, bool initiator) {
+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, "aes128-gcm: tried to init with short secret");
 
-	return method_session_init(ctx, secret, initiator);
+	return method_session_init(ctx, name, secret, initiator);
 }
 
 static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) {
@@ -235,7 +239,7 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_aes128_gcm = {
-	.name = "aes128-gcm",
+	.provides = method_provides,
 
 	.max_packet_size = method_max_packet_size,
 	.min_encrypt_head_space = method_min_encrypt_head_space,
diff --git a/src/methods/methods.c.in b/src/methods/methods.c.in
index 8f5bb10..f39fbc1 100644
--- a/src/methods/methods.c.in
+++ b/src/methods/methods.c.in
@@ -33,10 +33,10 @@ static const fastd_method_t *const methods[] = { @METHOD_LIST@
 };
 
 
-const fastd_method_t* fastd_method_get_by_name(const char *name) {
+const fastd_method_t* fastd_method_get_by_name(fastd_context_t *ctx, const char *name) {
 	size_t i;
 	for (i = 0; i < array_size(methods); i++) {
-		if (!strcmp(methods[i]->name, name))
+		if (methods[i]->provides(ctx, name))
 			return methods[i];
 	}
 
diff --git a/src/methods/null/null.c b/src/methods/null/null.c
index f49d94a..cba7931 100644
--- a/src/methods/null/null.c
+++ b/src/methods/null/null.c
@@ -33,6 +33,10 @@ struct fastd_method_session_state {
 };
 
 
+static bool method_provides(fastd_context_t *ctx UNUSED, const char *name) {
+	return !strcmp(name, "null");
+}
+
 static size_t method_max_packet_size(fastd_context_t *ctx) {
 	return fastd_max_packet_size(ctx);
 }
@@ -45,7 +49,7 @@ static size_t method_key_length(fastd_context_t *ctx UNUSED) {
 	return 0;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx UNUSED, const uint8_t *secret UNUSED, bool initiator) {
+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) {
 	fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
 
 	session->valid = true;
@@ -54,8 +58,8 @@ 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 uint8_t *secret, size_t length UNUSED, bool initiator) {
-	return method_session_init(ctx, secret, initiator);
+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 bool method_session_is_valid(fastd_context_t *ctx UNUSED, fastd_method_session_state_t *session) {
@@ -84,7 +88,7 @@ static bool method_passthrough(fastd_context_t *ctx UNUSED, fastd_peer_t *peer U
 }
 
 const fastd_method_t fastd_method_null = {
-	.name = "null",
+	.provides = method_provides,
 
 	.max_packet_size = method_max_packet_size,
 	.min_encrypt_head_space = method_min_head_tail_space,
diff --git a/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c b/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c
index 768e5c8..220e913 100644
--- a/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c
+++ b/src/methods/xsalsa20_poly1305/xsalsa20_poly1305.c
@@ -37,6 +37,10 @@ struct fastd_method_session_state {
 };
 
 
+static bool method_provides(fastd_context_t *ctx UNUSED, const char *name) {
+	return !strcmp(name, "xsalsa20-poly1305");
+}
+
 static size_t method_max_packet_size(fastd_context_t *ctx) {
 	return (fastd_max_packet_size(ctx) + COMMON_NONCEBYTES + crypto_secretbox_xsalsa20poly1305_ZEROBYTES - crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES);
 }
@@ -58,7 +62,7 @@ static size_t method_key_length(fastd_context_t *ctx UNUSED) {
 	return crypto_secretbox_xsalsa20poly1305_KEYBYTES;
 }
 
-static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const uint8_t *secret, bool initiator) {
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name 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);
@@ -68,11 +72,11 @@ 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 uint8_t *secret, size_t length, bool initiator) {
+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 < crypto_secretbox_xsalsa20poly1305_KEYBYTES)
 		exit_bug(ctx, "xsalsa20-poly1305: tried to init with short secret");
 
-	return method_session_init(ctx, secret, initiator);
+	return method_session_init(ctx, name, secret, initiator);
 }
 
 static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) {
@@ -162,7 +166,7 @@ static bool method_decrypt(fastd_context_t *ctx, fastd_peer_t *peer, fastd_metho
 }
 
 const fastd_method_t fastd_method_xsalsa20_poly1305 = {
-	.name = "xsalsa20-poly1305",
+	.provides = method_provides,
 
 	.max_packet_size = method_max_packet_size,
 	.min_encrypt_head_space = method_min_encrypt_head_space,
diff --git a/src/protocols/ec25519_fhmqvc/handshake.c b/src/protocols/ec25519_fhmqvc/handshake.c
index a9fc1a2..cb89462 100644
--- a/src/protocols/ec25519_fhmqvc/handshake.c
+++ b/src/protocols/ec25519_fhmqvc/handshake.c
@@ -102,12 +102,12 @@ static inline void new_session(fastd_context_t *ctx, fastd_peer_t *peer, const c
 		fastd_sha256_t secret[blocks];
 		derive_key(secret, blocks, salt, method_name, A, B, X, Y, sigma);
 
-		peer->protocol_state->session.method_state = method->session_init(ctx, (const uint8_t*)secret, initiator);
+		peer->protocol_state->session.method_state = method->session_init(ctx, method_name, (const uint8_t*)secret, initiator);
 	}
 	else {
 		fastd_sha256_t hash;
 		fastd_sha256_blocks(&hash, X->p, Y->p, A->p, B->p, sigma->p, NULL);
-		peer->protocol_state->session.method_state = method->session_init_compat(ctx, hash.b, HASHBYTES, initiator);
+		peer->protocol_state->session.method_state = method->session_init_compat(ctx, method_name, hash.b, HASHBYTES, initiator);
 	}
 
 	peer->protocol_state->session.established = ctx->now;
@@ -126,7 +126,7 @@ 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);
+	const fastd_method_t *method = fastd_method_get_by_name(ctx, method_name);
 	if (!salt && !method->session_init_compat) {
 		pr_warn(ctx, "can't establish session with %P[%I] (method without compat support)");
 		return false;