More implementation of dialer

conn/dialer.c

@@ -10,6 +10,8 @@
 #include "libp2p/utils/linked_list.h"
 #include "multiaddr/multiaddr.h"
 #include "libp2p/net/multistream.h"
+#include "libp2p/secio/secio.h"
+#include "libp2p/yamux/yamux.h"
 
 struct TransportDialer* libp2p_conn_tcp_transport_dialer_new();
 
@@ -64,10 +66,10 @@ void libp2p_conn_dialer_free(struct Dialer* in) {
  * be used instead (which calls this method internally).
  * @param dialer the dialer to use
  * @param muiltiaddress who to connect to
- * @returns a Connection, or NULL
+ * @returns a stream that is a ConnectionStream, or NULL
  */
-struct Connection* libp2p_conn_dialer_get_connection(const struct Dialer* dialer, const struct MultiAddress* multiaddress) {
+struct Stream* libp2p_conn_dialer_get_connection(const struct Dialer* dialer, const struct MultiAddress* multiaddress) {
-	struct Connection* conn = libp2p_conn_transport_dialer_get(dialer->transport_dialers, multiaddress);
+	struct Stream* conn = libp2p_conn_transport_dialer_get(dialer->transport_dialers, multiaddress);
 	if (conn == NULL) {
 		conn = dialer->fallback_dialer->dial(dialer->fallback_dialer, multiaddress);
 	}
@@ -75,12 +77,51 @@ struct Connection* libp2p_conn_dialer_get_connection(const struct Dialer* dialer
 }
 
 /***
- * Attempt to connect to a particular peer
+ * Attempt to connect to a particular peer. This will negotiate several protocols
  * @param dialer the dialer
  * @param peer the peer to join
+ * @returns true(1) on success, false(0) otherwise
  */
 int libp2p_conn_dialer_join_swarm(const struct Dialer* dialer, struct Libp2pPeer* peer, int timeout_secs) {
-	return 0;
+	// find the right Multiaddress
+	struct Libp2pLinkedList* current_entry = peer->addr_head;
+	struct Stream* conn_stream = NULL;
+	while (current_entry != NULL) {
+		struct MultiAddress* ma = current_entry->item;
+		conn_stream = libp2p_conn_dialer_get_connection(dialer, ma);
+		if (conn_stream != NULL) {
+			break;
+		}
+		current_entry = current_entry->next;
+	}
+	if (conn_stream == NULL)
+		return 0;
+	peer->sessionContext->insecure_stream = conn_stream;
+	peer->sessionContext->default_stream = conn_stream;
+	// multistream
+	struct Stream* new_stream = libp2p_net_multistream_stream_new(conn_stream);
+	if (new_stream != NULL) {
+		// secio over multistream
+		new_stream = libp2p_secio_stream_new(new_stream);
+		if (new_stream != NULL) {
+			peer->sessionContext->default_stream = new_stream;
+			// multistream over secio
+			new_stream = libp2p_net_multistream_stream_new(new_stream);
+			if (new_stream != NULL) {
+				peer->sessionContext->default_stream = new_stream;
+				// yamux over multistream
+				new_stream = libp2p_yamux_stream_new(new_stream);
+				if (new_stream != NULL) {
+					peer->sessionContext->default_stream = new_stream;
+					// identity over yamux
+					// kademlia over yamux
+					// circuit relay over yamux
+				}
+			}
+		}
+	}
+
+	return 1;
 }
 
 /**
@@ -90,17 +131,7 @@ int libp2p_conn_dialer_join_swarm(const struct Dialer* dialer, struct Libp2pPeer
  * @param protocol the protocol to use (right now only 'multistream' is supported)
  * @returns the ready-to-use stream
  */
-struct Stream* libp2p_conn_dialer_get_stream(const struct Dialer* dialer, const struct MultiAddress* multiaddress, const char* protocol) {
+struct Stream* libp2p_conn_dialer_get_stream(const struct Dialer* dialer, const struct Libp2pPeer* peer, const char* protocol) {
-	// this is a shortcut for now. Other protocols will soon be implemented
+	// TODO: Implement this method
-	if (strcmp(protocol, "multistream") != 0)
+	return NULL;
-		return NULL;
-	char* ip;
-	int port = multiaddress_get_ip_port(multiaddress);
-	if (!multiaddress_get_ip_address(multiaddress, &ip)) {
-		free(ip);
-		return NULL;
-	}
-	struct Stream* stream = libp2p_net_multistream_connect(ip, port);
-	free(ip);
-	return stream;
 }

conn/tcp_transport_dialer.c

@@ -4,6 +4,7 @@
 
 #include "multiaddr/multiaddr.h"
 #include "libp2p/net/p2pnet.h"
+#include "libp2p/net/connectionstream.h"
 #include "libp2p/conn/connection.h"
 #include "libp2p/conn/transport_dialer.h"
 #include "multiaddr/multiaddr.h"
@@ -13,36 +14,20 @@
  */
 
 int libp2p_conn_tcp_can_handle(const struct MultiAddress* addr) {
-	return 1;
+	return multiaddress_is_ip(addr);
 }
 
-int libp2p_conn_tcp_read(const struct Connection* connection, char** out, size_t* num_bytes) {
+struct Stream* libp2p_conn_tcp_dial(const struct TransportDialer* transport_dialer, const struct MultiAddress* addr) {
-	int buffer_size = 65535;
+	int socket_descriptor = socket_open4();
-	*out = (char*)malloc(buffer_size);
-	ssize_t bytes = socket_read(connection->socket_handle, *out, buffer_size, 0, 5);
-	*num_bytes = bytes;
-	return bytes > 0;
-}
-
-int libp2p_conn_tcp_write(const struct Connection* connection, const char* in, size_t num_bytes) {
-	ssize_t bytes = socket_write(connection->socket_handle, in, num_bytes, 0);
-	return bytes == num_bytes;
-}
-
-struct Connection* libp2p_conn_tcp_dial(const struct TransportDialer* transport_dialer, const struct MultiAddress* addr) {
-	struct Connection* conn = (struct Connection*) malloc(sizeof(struct Connection));
-	conn->socket_handle = socket_open4();
 	char* ip;
 	int port = multiaddress_get_ip_port(addr);
 	if (!multiaddress_get_ip_address(addr, &ip))
 		return NULL;
-	struct hostent* host = gethostbyname(ip);
+
+	struct Stream* stream = libp2p_net_connection_new(socket_descriptor, ip, port);
 	free(ip);
-	struct in_addr** addr_list = (struct in_addr**)host->h_addr_list;
+
-	socket_connect4(conn->socket_handle, (*addr_list[0]).s_addr, port);
+	return stream;
-	conn->read = libp2p_conn_tcp_read;
-	conn->write = libp2p_conn_tcp_write;
-	return conn;
 }
 
 struct TransportDialer* libp2p_conn_tcp_transport_dialer_new(char* peer_id, struct PrivateKey* private_key) {

conn/transport_dialer.c

@@ -33,7 +33,7 @@ void libp2p_conn_transport_dialer_free(struct TransportDialer* in) {
  * @param multiaddr the address
  * @returns a connection, or NULL if no appropriate dialer was found
  */
-struct Connection* libp2p_conn_transport_dialer_get(const struct Libp2pLinkedList* transport_dialers, const struct MultiAddress* multiaddr) {
+struct Stream* libp2p_conn_transport_dialer_get(const struct Libp2pLinkedList* transport_dialers, const struct MultiAddress* multiaddr) {
 	const struct Libp2pLinkedList* current = transport_dialers;
 	struct TransportDialer* t_dialer = NULL;
 	while (current != NULL) {

include/libp2p/conn/dialer.h

@@ -65,14 +65,14 @@ int libp2p_conn_dialer_join_swarm(const struct Dialer* dialer, struct Libp2pPeer
  * @param muiltiaddress who to connect to
  * @returns a Connection, or NULL
  */
-struct Connection* libp2p_conn_dialer_get_connection(const struct Dialer* dialer, const struct MultiAddress* multiaddress);
+struct Stream* libp2p_conn_dialer_get_connection(const struct Dialer* dialer, const struct MultiAddress* multiaddress);
 
 /**
  * return a Stream that is already set up to use the passed in protocol
  * @param dialer the dialer to use
- * @param multiaddress the host to dial
+ * @param peer the host
  * @param protocol the protocol to use (right now only 'multistream' is supported)
  * @returns the ready-to-use stream
  */
-struct Stream* libp2p_conn_dialer_get_stream(const struct Dialer* dialer, const struct MultiAddress* multiaddress, const char* protocol);
+struct Stream* libp2p_conn_dialer_get_stream(const struct Dialer* dialer, const struct Libp2pPeer* peer, const char* protocol);
 

include/libp2p/conn/transport_dialer.h

@@ -1,16 +1,17 @@
 #pragma once
 
 #include "multiaddr/multiaddr.h"
+#include "libp2p/net/stream.h"
 #include "libp2p/utils/linked_list.h"
 
 struct TransportDialer {
 	char* peer_id;
 	struct PrivateKey* private_key;
 	int (*can_handle)(const struct MultiAddress* multiaddr);
-	struct Connection* (*dial)(const struct TransportDialer* transport_dialer, const struct MultiAddress* multiaddr);
+	struct Stream* (*dial)(const struct TransportDialer* transport_dialer, const struct MultiAddress* multiaddr);
 };
 
 struct TransportDialer* libp2p_conn_transport_dialer_new(char* peer_id, struct PrivateKey* private_key);
 void libp2p_conn_transport_dialer_free(struct TransportDialer* in);
 
-struct Connection* libp2p_conn_transport_dialer_get(const struct Libp2pLinkedList* transport_dialers, const struct MultiAddress* multiaddr);
+struct Stream* libp2p_conn_transport_dialer_get(const struct Libp2pLinkedList* transport_dialers, const struct MultiAddress* multiaddr);

include/libp2p/net/multistream.h

@@ -95,6 +95,6 @@ int libp2p_net_multistream_negotiate(struct SessionContext* session);
  */
 struct KademliaMessage* libp2p_net_multistream_get_message(struct Stream* stream);
 
-struct Stream* libp2p_net_multistream_stream_new(int socket_fd, const char* ip, int port);
+struct Stream* libp2p_net_multistream_stream_new(struct Stream* parent_stream);
 
 void libp2p_net_multistream_stream_free(struct Stream* stream);

include/libp2p/net/stream.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <pthread.h>
+#include <stdint.h>
 
 /**
  * Encapsulates a message that (was/will be) sent
@@ -94,6 +95,10 @@ struct Stream {
 	int (*peek)(void* stream_context);
 };
 
+struct Stream* libp2p_stream_new();
+
+void libp2p_stream_free(struct Stream* stream);
+
 /***
  * Attempt to lock a stream for personal use. Does not block.
  * @param stream the stream to lock

include/libp2p/secio/secio.h

@@ -20,12 +20,12 @@ struct SecioContext {
 struct Libp2pProtocolHandler* libp2p_secio_build_protocol_handler(struct RsaPrivateKey* private_key, struct Peerstore* peer_store);
 
 /***
- * performs initial communication over an insecure channel to share
+ * Initiates a secio handshake. Use this method when you want to initiate a secio
- * keys, IDs, and initiate connection. This is a framed messaging system
+ * session. This should not be used to respond to incoming secio requests
- * @param ctx the SecioContext
+ * @param parent_stream the parent stream
- * @returns true(1) on success, false(0) otherwise
+ * @returns a Secio Stream
  */
-int libp2p_secio_handshake(struct SecioContext* ctx);
+struct Stream* libp2p_secio_stream_new(struct Stream* parent_stream);
 
 /***
  * Initiates a secio handshake. Use this method when you want to initiate a secio
@@ -47,3 +47,15 @@ int libp2p_secio_send_protocol(struct SecioContext* session);
  * @returns true(1) if we received what we think we should have, false(0) otherwise
  */
 int libp2p_secio_receive_protocol(struct SecioContext* session);
+
+/***
+ * performs initial communication over an insecure channel to share
+ * keys, IDs, and initiate connection. This is a framed messaging system
+ * NOTE: session must contain a valid socket_descriptor that is a multistream.
+ * @param local_session the secure session to be filled
+ * @param private_key our private key to use
+ * @param peerstore the collection of peers
+ * @returns true(1) on success, false(0) otherwise
+ */
+int libp2p_secio_handshake(struct SecioContext* secio_context);
+

include/libp2p/yamux/yamux.h

@@ -1,6 +1,11 @@
 #pragma once
 
 #include "libp2p/net/protocol.h"
+#include "libp2p/net/stream.h"
+
+/***
+ * Declarations for the Yamux protocol
+ */
 
 /**
  * Build a handler that can handle the yamux protocol
@@ -21,3 +26,5 @@ int yamux_send_protocol(struct SessionContext* context);
  * @returns true(1) on success, false(0) otherwise
  */
 int yamux_receive_protocol(struct SessionContext* context);
+
+struct Stream* libp2p_yamux_stream_new(struct Stream* parent_stream);

net/Makefile

@@ -7,7 +7,7 @@ endif
 
 LFLAGS = 
 DEPS = 
-OBJS = sctp.o socket.o tcp.o udp.o multistream.o protocol.o connectionstream.o
+OBJS = sctp.o socket.o tcp.o udp.o multistream.o protocol.o connectionstream.o stream.o
 
 %.o: %.c $(DEPS)
 	$(CC) -c -o $@ $< $(CFLAGS)

net/multistream.c

@@ -310,7 +310,8 @@ struct Stream* libp2p_net_multistream_connect_with_timeout(const char* hostname,
 		goto exit;
 
 	// send the multistream handshake
-	stream = libp2p_net_multistream_stream_new(socket, hostname, port);
+	// TODO: wire this back in
+	//stream = libp2p_net_multistream_stream_new(socket, hostname, port, NULL);
 	if (stream == NULL)
 		goto exit;
 
@@ -391,17 +392,15 @@ void libp2p_net_multistream_stream_free(struct Stream* stream) {
  * @param ip the IP address
  * @param port the port
  */
-struct Stream* libp2p_net_multistream_stream_new(int socket_fd, const char* ip, int port) {
+struct Stream* libp2p_net_multistream_stream_new(struct Stream* parent_stream) {
 	struct Stream* out = (struct Stream*)malloc(sizeof(struct Stream));
 	if (out != NULL) {
-		out->parent_stream = NULL;
+		out->parent_stream = parent_stream;
 		out->close = libp2p_net_multistream_close;
 		out->read = libp2p_net_multistream_read;
 		out->write = libp2p_net_multistream_write;
 		out->peek = libp2p_net_multistream_peek;
-		char str[strlen(ip) + 50];
+		out->address = parent_stream->address;
-		sprintf(str, "/ip4/%s/tcp/%d", ip, port);
-		out->address = multiaddress_new_from_string(str);
 	}
 	return out;
 }

net/stream.c

@@ -0,0 +1,25 @@
+#include <stdlib.h>
+
+#include "libp2p/net/stream.h"
+
+struct Stream* libp2p_stream_new() {
+	struct Stream* stream = (struct Stream*) malloc(sizeof(struct Stream));
+	if (stream != NULL) {
+		stream->address = NULL;
+		stream->close = NULL;
+		stream->parent_stream = NULL;
+		stream->peek = NULL;
+		stream->read = NULL;
+		stream->read_raw = NULL;
+		stream->socket_mutex = NULL;
+		stream->stream_context = NULL;
+		stream->write = NULL;
+	}
+	return stream;
+}
+
+void libp2p_stream_free(struct Stream* stream) {
+	if (stream != NULL) {
+		free(stream);
+	}
+}

secio/secio.c

@@ -72,17 +72,28 @@ int libp2p_secio_shutdown(void* context) {
 /***
  * Initiates a secio handshake. Use this method when you want to initiate a secio
  * session. This should not be used to respond to incoming secio requests
- * @param session_context the session context
+ * @param parent_stream the parent stream
- * @param private_key the RSA private key to use
+ * @returns a Secio Stream
- * @param peer_store the peer store
- * @returns true(1) on success, false(0) otherwise
  */
-int libp2p_secio_initiate_handshake(struct SecioContext* ctx) {
+struct Stream* libp2p_secio_stream_new(struct Stream* parent_stream) {
-	if (libp2p_secio_send_protocol(ctx) && libp2p_secio_receive_protocol(ctx)) {
+	struct Stream* new_stream = libp2p_stream_new();
-		return libp2p_secio_handshake(ctx);
+	if (new_stream != NULL) {
+		struct SecioContext* ctx = (struct SecioContext*) malloc(sizeof(struct SecioContext));
+		if (ctx == NULL) {
+			libp2p_stream_free(new_stream);
+			new_stream = NULL;
+			return NULL;
+		}
+		new_stream->stream_context = ctx;
+		new_stream->parent_stream = parent_stream;
+		if (!libp2p_secio_send_protocol(ctx)
+				|| !libp2p_secio_receive_protocol(ctx)
+				|| !libp2p_secio_handshake(ctx)) {
+			libp2p_stream_free(new_stream);
+			new_stream = NULL;
+		}
 	}
-	libp2p_logger_error("secio", "Secio protocol exchange failed.\n");
+	return new_stream;
-	return 0;
 }
 
 struct Libp2pProtocolHandler* libp2p_secio_build_protocol_handler(struct RsaPrivateKey* private_key, struct Peerstore* peer_store) {

test/test_conn.h

@@ -29,7 +29,7 @@ int test_dialer_dial() {
 	struct PrivateKey* private_key = NULL;
 	struct Dialer* dialer = NULL;
 	struct MultiAddress* destination_address = NULL;
-	struct Connection* conn = NULL;
+	struct Stream* conn = NULL;
 	char* result = NULL;
 	size_t result_size = 0;
 	struct Libp2pPeer* peer = libp2p_peer_new();
@@ -60,7 +60,6 @@ int test_dialer_dial() {
 	free(peer_id);
 	multiaddress_free(destination_address);
 	libp2p_conn_dialer_free(dialer);
-	libp2p_conn_connection_free(conn);
 	return retVal;
 }
 
@@ -92,7 +91,7 @@ int test_dialer_dial_multistream() {
 		goto exit;
 
 	// now try to dial
-	stream = libp2p_conn_dialer_get_stream(dialer, destination_address, "multistream");
+	stream = libp2p_conn_dialer_get_stream(dialer, peer, "multistream");
 	if (stream == NULL)
 		goto exit;
 

test/test_secio.h

@@ -95,33 +95,6 @@ int test_secio_handshake() {
 	}
 
 	// attempt to write the protocol, and see what comes back
-	/*
-	char* protocol = "/secio/1.0.0\n";
-	int protocol_size = strlen(protocol);
-	secure_session->insecure_stream->write(secure_session, (unsigned char*)protocol, protocol_size);
-
-	unsigned char* buffer = NULL;
-	size_t bytes_read = 0;
-	int timeout = 30;
-	secure_session->insecure_stream->read(secure_session, &buffer, &bytes_read, timeout);
-
-	if (!libp2p_secio_handshake(secure_session, rsa_private_key, peerstore)) {
-		fprintf(stderr, "test_secio_handshake: Unable to do handshake\n");
-		if (secure_session->shared_key != NULL) {
-			fprintf(stdout, "Shared key: ");
-			for(int i = 0; i < secure_session->shared_key_size; i++)
-				fprintf(stdout, "%d ", secure_session->shared_key[i]);
-			fprintf(stdout, "\nLocal stretched key: ");
-			print_stretched_key(secure_session->local_stretched_key);
-			fprintf(stdout, "\nRemote stretched key: ");
-			print_stretched_key(secure_session->remote_stretched_key);
-			fprintf(stdout, "\n");
-		}
-		goto exit;
-	}
-	*/
-	/*
-	// a new way to do the above
 	if (!libp2p_secio_initiate_handshake(secure_session, rsa_private_key, peerstore)) {
 		libp2p_logger_error("test_secio", "Unable to do handshake\n");
 		if (secure_session->shared_key != NULL) {
@@ -137,17 +110,6 @@ int test_secio_handshake() {
 		goto exit;
 	}
 
-	/*
-	fprintf(stdout, "Shared key: ");
-	for(int i = 0; i < secure_session.shared_key_size; i++)
-		fprintf(stdout, "%d ", secure_session.shared_key[i]);
-	fprintf(stdout, "\nLocal stretched key: ");
-	print_stretched_key(secure_session.local_stretched_key);
-	fprintf(stdout, "\nRemote stretched key: ");
-	print_stretched_key(secure_session.remote_stretched_key);
-	fprintf(stdout, "\n");
-	*/
-	/*
 	// now attempt to do something with it... try to negotiate a multistream
 	if (libp2p_net_multistream_negotiate(secure_session) == 0) {
 		fprintf(stdout, "Unable to negotiate multistream\n");
@@ -197,27 +159,6 @@ int test_secio_handshake() {
 	exit:
 	if (peerstore != NULL)
 		libp2p_peerstore_free(peerstore);
-	/*
-	if (secure_session.insecure_stream != NULL)
-		libp2p_net_multistream_stream_free(secure_session.insecure_stream);
-	if (secure_session.local_stretched_key != NULL)
-		libp2p_crypto_ephemeral_stretched_key_free(secure_session.local_stretched_key);
-	if (secure_session.remote_stretched_key != NULL)
-		libp2p_crypto_ephemeral_stretched_key_free(secure_session.remote_stretched_key);
-	if (secure_session.ephemeral_private_key != NULL)
-		libp2p_crypto_ephemeral_key_free(secure_session.ephemeral_private_key);
-	if (secure_session.remote_ephemeral_public_key != NULL)
-		free(secure_session.remote_ephemeral_public_key);
-	if (secure_session.chosen_cipher != NULL)
-		free(secure_session.chosen_cipher);
-	if (secure_session.chosen_curve != NULL)
-		free(secure_session.chosen_curve);
-	if (secure_session.chosen_hash != NULL)
-		free(secure_session.chosen_hash);
-	if (secure_session.shared_key != NULL)
-		free(secure_session.shared_key);
-	*/
-	/*
 	if (private_key != NULL)
 		libp2p_crypto_private_key_free(private_key);
 	if (decode_base64 != NULL)
@@ -442,32 +383,6 @@ int test_secio_handshake_go() {
 	}
 
 	// attempt to write the protocol, and see what comes back
-	/*
-	char* protocol = "/secio/1.0.0\n";
-	int protocol_size = strlen(protocol);
-	secure_session->insecure_stream->write(secure_session, (unsigned char*)protocol, protocol_size);
-
-	unsigned char* buffer = NULL;
-	size_t bytes_read = 0;
-	int timeout = 30;
-	secure_session->insecure_stream->read(secure_session, &buffer, &bytes_read, timeout);
-	if (!libp2p_secio_handshake(secure_session, rsa_private_key, peerstore)) {
-		fprintf(stderr, "test_secio_handshake: Unable to do handshake\n");
-		if (secure_session->shared_key != NULL) {
-			fprintf(stdout, "Shared key: ");
-			for(int i = 0; i < secure_session->shared_key_size; i++)
-				fprintf(stdout, "%d ", secure_session->shared_key[i]);
-			fprintf(stdout, "\nLocal stretched key: ");
-			print_stretched_key(secure_session->local_stretched_key);
-			fprintf(stdout, "\nRemote stretched key: ");
-			print_stretched_key(secure_session->remote_stretched_key);
-			fprintf(stdout, "\n");
-		}
-		goto exit;
-	}
-	*/
-	/*
-	// a new way to do the above
 	if (!libp2p_secio_initiate_handshake(secure_session, rsa_private_key, peerstore)) {
 		libp2p_logger_error("test_secio", "Unable to do handshake.\n");
 		if (secure_session->shared_key != NULL) {
@@ -483,17 +398,6 @@ int test_secio_handshake_go() {
 		goto exit;
 	}
 
-	/*
-	fprintf(stdout, "Shared key: ");
-	for(int i = 0; i < secure_session.shared_key_size; i++)
-		fprintf(stdout, "%d ", secure_session.shared_key[i]);
-	fprintf(stdout, "\nLocal stretched key: ");
-	print_stretched_key(secure_session.local_stretched_key);
-	fprintf(stdout, "\nRemote stretched key: ");
-	print_stretched_key(secure_session.remote_stretched_key);
-	fprintf(stdout, "\n");
-	*/
-	/*
 	// now attempt to do something with it... try to negotiate a multistream
 	if (libp2p_net_multistream_negotiate(secure_session) == 0) {
 		fprintf(stdout, "Unable to negotiate multistream\n");

yamux/yamux.c

@@ -170,3 +170,12 @@ struct Libp2pProtocolHandler* yamux_build_protocol_handler(struct Libp2pVector*
 	}
 	return handler;
 }
+
+/***
+ * Negotiate the Yamux protocol
+ * @param parent_stream the parent stream
+ * @returns a Stream initialized and ready for yamux
+ */
+struct Stream* libp2p_yamux_stream_new(struct Stream* parent_stream) {
+	return NULL;
+}