/*
 * ZeroTier One - Network Virtualization Everywhere
 * Copyright (C) 2011-2015  ZeroTier, Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * --
 *
 * ZeroTier may be used and distributed under the terms of the GPLv3, which
 * are available at: http://www.gnu.org/licenses/gpl-3.0.html
 *
 * If you would like to embed ZeroTier into a commercial application or
 * redistribute it in a modified binary form, please contact ZeroTier Networks
 * LLC. Start here: http://www.zerotier.com/
 */

#ifndef ZT_NETCONETHERNETTAP_HPP
#define ZT_NETCONETHERNETTAP_HPP

#include <stdio.h>
#include <stdlib.h>

#include <string>
#include <vector>
#include <utility>
#include <stdexcept>
#include <stdint.h>

#include "../node/Constants.hpp"
#include "../node/MulticastGroup.hpp"
#include "../node/Mutex.hpp"
#include "../node/InetAddress.hpp"
#include "../osdep/Thread.hpp"
#include "../osdep/Phy.hpp"

#include "netif/etharp.h"

#include "RPC.h"

struct tcp_pcb;
struct socket_st;
struct listen_st;
struct bind_st;
struct connect_st;
struct getsockname_st;
struct accept_st;

#define APPLICATION_POLL_FREQ           2
#define ZT_LWIP_TCP_TIMER_INTERVAL      5
#define STATUS_TMR_INTERVAL             250 // How often we check connection statuses (in ms)
#define DEFAULT_BUF_SZ                  1024 * 1024 * 2
#define DEFAULT_BUF_SOFTMAX				DEFAULT_BUF_SZ / 2

namespace ZeroTier {

class NetconEthernetTap;
class LWIPStack;

/*
 * TCP connection administered by service
 */
struct TcpConnection
{
  bool listening, probation;
  int pid, txsz, rxsz;
  PhySocket *rpcSock, *sock;
  struct tcp_pcb *pcb;
  struct sockaddr_storage *addr;
  unsigned char txbuf[DEFAULT_BUF_SZ];
  unsigned char rxbuf[DEFAULT_BUF_SZ];
};

/*
 * A helper for passing a reference to _phy to LWIP callbacks as a "state"
 */
struct Larg
{
  NetconEthernetTap *tap;
  TcpConnection *conn;
  Larg(NetconEthernetTap *_tap, TcpConnection *conn) : tap(_tap), conn(conn) {}
};

/*
 * Network Containers instance -- emulates an Ethernet tap device as far as OneService knows
 */
class NetconEthernetTap
{
	friend class Phy<NetconEthernetTap *>;

public:
	NetconEthernetTap(
		const char *homePath,
		const MAC &mac,
		unsigned int mtu,
		unsigned int metric,
		uint64_t nwid,
		const char *friendlyName,
		void (*handler)(void *,uint64_t,const MAC &,const MAC &,unsigned int,unsigned int,const void *,unsigned int),
		void *arg);

	~NetconEthernetTap();

	void setEnabled(bool en);
	bool enabled() const;
	bool addIp(const InetAddress &ip);
	bool removeIp(const InetAddress &ip);
	std::vector<InetAddress> ips() const;
	void put(const MAC &from,const MAC &to,unsigned int etherType,const void *data,unsigned int len);
	std::string deviceName() const;
	void setFriendlyName(const char *friendlyName);
	void scanMulticastGroups(std::vector<MulticastGroup> &added,std::vector<MulticastGroup> &removed);

	void threadMain()
		throw();

	LWIPStack *lwipstack;
  uint64_t _nwid;
  void (*_handler)(void *,uint64_t,const MAC &,const MAC &,unsigned int,unsigned int,const void *,unsigned int);
  void *_arg;

private:
	// LWIP callbacks
	// NOTE: these are called from within LWIP, meaning that lwipstack->_lock is ALREADY
	// locked in this case!

	/*
	 * Callback from LWIP for when a connection has been accepted and the PCB has been
	 * put into an ACCEPT state.
	 *
	 * A socketpair is created, one end is kept and wrapped into a PhySocket object
	 * for use in the main ZT I/O loop, and one end is sent to the client. The client
	 * is then required to tell the service what new file descriptor it has allocated
	 * for this connection. After the mapping is complete, the accepted socket can be
	 * used.
	 *
	 * @param associated service state object
	 * @param newly allocated PCB
	 * @param error code
	 * @return ERR_OK if everything is ok, -1 otherwise
	 *
	 *	 i := should be implemented in intercept lib
	 *	 I := is implemented in intercept lib
	 *	 X := is implemented in service
	 *	 ? := required treatment Unknown
	 *	 - := Not needed
	 *
	 *	[ ] EAGAIN or EWOULDBLOCK - The socket is marked nonblocking and no connections are present
	 *													to be accepted. POSIX.1-2001 allows either error to be returned for
	 *													this case, and does not require these constants to have the same value,
	 *													so a portable application should check for both possibilities.
	 *	[I] EBADF - The descriptor is invalid.
	 *	[I] ECONNABORTED - A connection has been aborted.
	 *	[i] EFAULT - The addr argument is not in a writable part of the user address space.
	 *	[-] EINTR - The system call was interrupted by a signal that was caught before a valid connection arrived; see signal(7).
	 *	[I] EINVAL - Socket is not listening for connections, or addrlen is invalid (e.g., is negative).
	 *	[I] EINVAL - (accept4()) invalid value in flags.
	 *	[I] EMFILE - The per-process limit of open file descriptors has been reached.
	 *	[ ] ENFILE - The system limit on the total number of open files has been reached.
	 *	[ ] ENOBUFS, ENOMEM - Not enough free memory. This often means that the memory allocation is
	 *												limited by the socket buffer limits, not by the system memory.
	 *	[I] ENOTSOCK - The descriptor references a file, not a socket.
	 *	[I] EOPNOTSUPP - The referenced socket is not of type SOCK_STREAM.
	 *	[ ] EPROTO - Protocol error.
	 *
	 */
	static err_t nc_accept(void *arg, struct tcp_pcb *newPCB, err_t err);

	/*
	 * Callback from LWIP for when data is available to be read from the network.
	 *
	 * Data is in the form of a linked list of struct pbufs, it is then recombined and
	 * send to the client over the associated unix socket.
	 *
	 * @param associated service state object
	 * @param allocated PCB
	 * @param chain of pbufs
	 * @param error code
	 * @return ERR_OK if everything is ok, -1 otherwise
	 *
	 */
 	static err_t nc_recved(void *arg, struct tcp_pcb *PCB, struct pbuf *p, err_t err);

	/*
	 * Callback from LWIP when an internal error is associtated with the given (arg)
	 *
	 * Since the PCB related to this error might no longer exist, only its perviously
	 * associated (arg) is provided to us.
	 *
	 * @param associated service state object
	 * @param error code
	 *
	 */
	static void nc_err(void *arg, err_t err);

	/*
	 * Callback from LWIP to do whatever work we might need to do.
	 *
	 * @param associated service state object
	 * @param PCB we're polling on
	 * @return ERR_OK if everything is ok, -1 otherwise
	 *
	 */
	static err_t nc_poll(void* arg, struct tcp_pcb *PCB);

	/*
	 * Callback from LWIP to signal that 'len' bytes have successfully been sent.
	 * As a result, we should put our socket back into a notify-on-readability state
	 * since there is now room on the PCB buffer to write to.
	 *
	 * NOTE: This could be used to track the amount of data sent by a connection.
	 *
	 * @param associated service state object
	 * @param relevant PCB
	 * @param length of data sent
	 * @return ERR_OK if everything is ok, -1 otherwise
	 *
	 */
	static err_t nc_sent(void *arg, struct tcp_pcb *PCB, u16_t len);

	/*
	 * Callback from LWIP which sends a return value to the client to signal that
	 * a connection was established for this PCB
	 *
	 * @param associated service state object
	 * @param relevant PCB
	 * @param error code
	 * @return ERR_OK if everything is ok, -1 otherwise
	 *
	 */
	static err_t nc_connected(void *arg, struct tcp_pcb *PCB, err_t err);
	
	//static void nc_close(struct tcp_pcb *PCB);
	//static err_t nc_send(struct tcp_pcb *PCB);

	/*
	 * Handles an RPC to bind an LWIP PCB to a given address and port
	 *
	 * @param PhySocket associated with this RPC connection
	 * @param structure containing the data and parameters for this client's RPC
	 *

	 i := should be implemented in intercept lib
	 I := is implemented in intercept lib
	 X := is implemented in service
	 ? := required treatment Unknown
	 - := Not needed

	[ ]	EACCES - The address is protected, and the user is not the superuser.
	[X]	EADDRINUSE - The given address is already in use.
	[I]	EBADF - sockfd is not a valid descriptor.
	[X]	EINVAL - The socket is already bound to an address.
	[I]	ENOTSOCK - sockfd is a descriptor for a file, not a socket.

	[X]	ENOMEM - Insufficient kernel memory was available.

	  - The following errors are specific to UNIX domain (AF_UNIX) sockets:

	[-]	EACCES - Search permission is denied on a component of the path prefix. (See also path_resolution(7).)
	[-]	EADDRNOTAVAIL - A nonexistent interface was requested or the requested address was not local.
	[-]	EFAULT - addr points outside the user's accessible address space.
	[-]	EINVAL - The addrlen is wrong, or the socket was not in the AF_UNIX family.
	[-]	ELOOP - Too many symbolic links were encountered in resolving addr.
	[-]	ENAMETOOLONG - s addr is too long.
	[-]	ENOENT - The file does not exist.
	[-]	ENOTDIR - A component of the path prefix is not a directory.
	[-]	EROFS - The socket inode would reside on a read-only file system.
	 */
	void handleBind(PhySocket *sock, PhySocket *rpcsock, void **uptr, struct bind_st *bind_rpc);
	
	/*
	 * Handles an RPC to put an LWIP PCB into LISTEN mode
	 *
	 * @param PhySocket associated with this RPC connection
	 * @param structure containing the data and parameters for this client's RPC
	 *

	 i := should be implemented in intercept lib
	 I := is implemented in intercept lib
	 X := is implemented in service
	 ? := required treatment Unknown
	 - := Not needed

	[?] EADDRINUSE - Another socket is already listening on the same port.
	[IX] EBADF - The argument sockfd is not a valid descriptor.
	[I] ENOTSOCK - The argument sockfd is not a socket.
	[I] EOPNOTSUPP - The socket is not of a type that supports the listen() operation.
	 */
	void handleListen(PhySocket *sock, PhySocket *rpcsock, void **uptr, struct listen_st *listen_rpc);
	
	/*
	 * Handles an RPC to create a socket (LWIP PCB and associated socketpair)
	 *
	 * A socketpair is created, one end is kept and wrapped into a PhySocket object
	 * for use in the main ZT I/O loop, and one end is sent to the client. The client
	 * is then required to tell the service what new file descriptor it has allocated
	 * for this connection. After the mapping is complete, the socket can be used.
	 *
	 * @param PhySocket associated with this RPC connection
	 * @param structure containing the data and parameters for this client's RPC
	 *

	 i := should be implemented in intercept lib
	 I := is implemented in intercept lib
	 X := is implemented in service
	 ? := required treatment Unknown
	 - := Not needed

	[-] EACCES - Permission to create a socket of the specified type and/or protocol is denied.
	[I] EAFNOSUPPORT - The implementation does not support the specified address family.
	[I] EINVAL - Unknown protocol, or protocol family not available.
	[I] EINVAL - Invalid flags in type.
	[I] EMFILE - Process file table overflow.
	[?] ENFILE - The system limit on the total number of open files has been reached.
	[X] ENOBUFS or ENOMEM - Insufficient memory is available.  The socket cannot be created until sufficient resources are freed.
	[?] EPROTONOSUPPORT - The protocol type or the specified protocol is not supported within this domain.
	 */
	TcpConnection * handleSocket(PhySocket *sock, void **uptr, struct socket_st* socket_rpc);
	
	/*
	 * Handles an RPC to connect to a given address and port
	 *
	 * @param PhySocket associated with this RPC connection
	 * @param structure containing the data and parameters for this client's RPC

	--- Error handling in this method will only catch problems which are immedately
	    apprent. Some errors will need to be caught in the nc_connected(0 callback

	 i := should be implemented in intercept lib
 	 I := is implemented in intercept lib
 	 X := is implemented in service
 	 ? := required treatment Unknown
 	 - := Not needed

	[-] EACCES - For UNIX domain sockets, which are identified by pathname: Write permission is denied ...
	[?] EACCES, EPERM - The user tried to connect to a broadcast address without having the socket broadcast flag enabled ...
	[X] EADDRINUSE - Local address is already in use.
	[I] EAFNOSUPPORT - The passed address didn't have the correct address family in its sa_family field.
	[X] EAGAIN - No more free local ports or insufficient entries in the routing cache.
	[ ] EALREADY - The socket is nonblocking and a previous connection attempt has not yet been completed.
	[IX] EBADF - The file descriptor is not a valid index in the descriptor table.
	[ ] ECONNREFUSED - No-one listening on the remote address.
	[i] EFAULT - The socket structure address is outside the user's address space.
	[ ] EINPROGRESS - The socket is nonblocking and the connection cannot be completed immediately.
	[-] EINTR - The system call was interrupted by a signal that was caught.
	[X] EISCONN - The socket is already connected.
	[X] ENETUNREACH - Network is unreachable.
	[I] ENOTSOCK - The file descriptor is not associated with a socket.
	[X] ETIMEDOUT - Timeout while attempting connection.

	[X] EINVAL - Invalid argument, SVr4, generally makes sense to set this
	 */
	void handleConnect(PhySocket *sock, PhySocket *rpcsock, TcpConnection *conn, struct connect_st* connect_rpc);
	
	/* 
	 * Return the address that the socket is bound to 
	 */
	void handleGetsockname(PhySocket *sock, PhySocket *rpcsock, void **uptr, struct getsockname_st *getsockname_rpc);

	/* 
 	 * Writes data from the application's socket to the LWIP connection
 	 */
	void handleWrite(TcpConnection *conn);

	/*
	 * Sends a return value to the intercepted application
	 */
	int sendReturnValue(PhySocket *sock, int retval, int _errno);
	int sendReturnValue(int fd, int retval, int _errno);

	/* 
 	* Unpacks the buffer from an RPC command
 	*/
	void unloadRPC(void *data, pid_t &pid, pid_t &tid, 
		int &rpc_count, char (timestamp[RPC_TIMESTAMP_SZ]), char (magic[sizeof(uint64_t)]), char &cmd, void* &payload);

	// Unused -- no UDP or TCP from this thread/Phy<>
	void phyOnDatagram(PhySocket *sock,void **uptr,const struct sockaddr *from,void *data,unsigned long len);
	void phyOnTcpConnect(PhySocket *sock,void **uptr,bool success);
	void phyOnTcpAccept(PhySocket *sockL,PhySocket *sockN,void **uptrL,void **uptrN,const struct sockaddr *from);
	void phyOnTcpClose(PhySocket *sock,void **uptr);
	void phyOnTcpData(PhySocket *sock,void **uptr,void *data,unsigned long len);
	void phyOnTcpWritable(PhySocket *sock,void **uptr);

	/*
 	 * Signals us to close the TcpConnection associated with this PhySocket
 	 */
	void phyOnUnixClose(PhySocket *sock,void **uptr);
	
    /* 
 	 * Notifies us that there is data to be read from an application's socket
 	 */
	void phyOnUnixData(PhySocket *sock,void **uptr,void *data,unsigned long len);
	
	/* 
 	 * Notifies us that we can write to an application's socket
 	 */
	void phyOnUnixWritable(PhySocket *sock,void **uptr,bool lwip_invoked);

	/*
 	 * Returns a pointer to a TcpConnection associated with a given PhySocket
 	 */
	TcpConnection *getConnection(PhySocket *sock);

	/*
 	 * Closes a TcpConnection, associated LWIP PCB strcuture, 
 	 * PhySocket, and underlying file descriptor
 	 */
	void closeConnection(PhySocket *sock);

	ip_addr_t convert_ip(struct sockaddr_in * addr)
	{
	  ip_addr_t conn_addr;
	  struct sockaddr_in *ipv4 = addr;
	  short a = ip4_addr1(&(ipv4->sin_addr));
	  short b = ip4_addr2(&(ipv4->sin_addr));
	  short c = ip4_addr3(&(ipv4->sin_addr));
	  short d = ip4_addr4(&(ipv4->sin_addr));
	  IP4_ADDR(&conn_addr, a,b,c,d);
	  return conn_addr;
	}

	Phy<NetconEthernetTap *> _phy;
	PhySocket *_unixListenSocket;

	std::vector<TcpConnection*> _TcpConnections;
	std::map<uint64_t, std::pair<PhySocket*, void*> > jobmap;

	pid_t rpcCounter;
	netif interface;

	MAC _mac;
	Thread _thread;
	std::string _homePath;
	std::string _dev; // path to Unix domain socket

	std::vector<MulticastGroup> _multicastGroups;
	Mutex _multicastGroups_m;

	std::vector<InetAddress> _ips;
	Mutex _ips_m, _tcpconns_m, _rx_buf_m;

	unsigned int _mtu;
	volatile bool _enabled;
	volatile bool _run;
};

} // namespace ZeroTier

#endif