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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* 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 (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file
* Interface functions to the internal and external multiplexers.
*/
#ifndef FORWARD_H
#define FORWARD_H
#include "openvpn.h"
#include "occ.h"
#include "ping.h"
#define TUN_OUT(c) (BLEN(&(c)->c2.to_tun) > 0)
#define LINK_OUT(c) (BLEN(&(c)->c2.to_link) > 0)
#define ANY_OUT(c) (TUN_OUT(c) || LINK_OUT(c))
#ifdef ENABLE_FRAGMENT
#define TO_LINK_FRAG(c) ((c)->c2.fragment && fragment_outgoing_defined ((c)->c2.fragment))
#else
#define TO_LINK_FRAG(c) (false)
#endif
#define TO_LINK_DEF(c) (LINK_OUT(c) || TO_LINK_FRAG(c))
#define IOW_TO_TUN (1<<0)
#define IOW_TO_LINK (1<<1)
#define IOW_READ_TUN (1<<2)
#define IOW_READ_LINK (1<<3)
#define IOW_SHAPER (1<<4)
#define IOW_CHECK_RESIDUAL (1<<5)
#define IOW_FRAG (1<<6)
#define IOW_MBUF (1<<7)
#define IOW_READ_TUN_FORCE (1<<8)
#define IOW_WAIT_SIGNAL (1<<9)
#define IOW_READ (IOW_READ_TUN|IOW_READ_LINK)
void pre_select (struct context *c);
void process_io (struct context *c);
const char *wait_status_string (struct context *c, struct gc_arena *gc);
void show_wait_status (struct context *c);
/**********************************************************************/
/**
* Process a data channel packet that will be sent through a VPN tunnel.
* @ingroup data_control
*
* This function controls the processing of a data channel packet which
* will be sent through a VPN tunnel to a remote OpenVPN peer. It's
* general structure is as follows:
* - Check that the client authentication has succeeded; if not, drop the
* packet.
* - If the \a comp_frag argument is true:
* - Call \c lzo_compress() of the \link Data Channel Compression
* module\endlink to (possibly) compress the packet.
* - Call \c fragment_outgoing() of the \link Data Channel Fragmentation
* module\endlink to (possibly) fragment the packet.
* - Activate the \link Data Channel Crypto module\endlink to perform
* security operations on the packet.
* - Call \c tls_pre_encrypt() to choose the appropriate security
* parameters for this packet.
* - Call \c openvpn_encrypt() to encrypt and HMAC signed the packet.
* - Call \c tls_post_encrypt() to prepend the one-byte OpenVPN header
* and do some TLS accounting.
* - Place the resulting packet in \c c->c2.to_link so that it can be sent
* over the external network interface to its remote destination by the
* \link external_multiplexer External Multiplexer\endlink.
*
* @param c - The context structure of the VPN tunnel associated with this
* packet.
* @param comp_frag - Whether to do packet compression and fragmentation.
* This flag is set to true the first time a packet is processed. If
* the packet then gets fragmented, this function will be called again
* once for each remaining fragment with this parameter set to false.
*/
void encrypt_sign (struct context *c, bool comp_frag);
/**********************************************************************/
/**
* Read a packet from the external network interface.
* @ingroup external_multiplexer
*
* The packet read from the external network interface is stored in \c
* c->c2.buf and its source address in \c c->c2.from. If an error
* occurred, the length of \c c->c2.buf will be 0.
*
* OpenVPN running as client or as UDP server only has a single external
* network socket, so this function can be called with the single (client
* mode) or top level (UDP server) context as its argument. OpenVPN
* running as TCP server, on the other hand, has a network socket for each
* active VPN tunnel. In that case this function must be called with the
* context associated with the appropriate VPN tunnel for which data is
* available to be read.
*
* @param c - The context structure which contains the external
* network socket from which to read incoming packets.
*/
void read_incoming_link (struct context *c);
/**
* Process a packet read from the external network interface.
* @ingroup external_multiplexer
*
* This function controls the processing of a data channel packet which
* has come out of a VPN tunnel. It's high-level structure is as follows:
* - Verify that a nonzero length packet has been received from a valid
* source address for the given context \a c.
* - Call \c tls_pre_decrypt(), which splits data channel and control
* channel packets:
* - If a data channel packet, the appropriate security parameters are
* loaded.
* - If a control channel packet, this function process is it and
* afterwards sets the packet's buffer length to 0, so that the data
* channel processing steps below will ignore it.
* - Call \c openvpn_decrypt() of the \link data_crypto Data Channel
* Crypto module\endlink to authenticate and decrypt the packet using
* the security parameters loaded by \c tls_pre_decrypt() above.
* - Call \c fragment_incoming() of the \link fragmentation Data Channel
* Fragmentation module\endlink to reassemble the packet if it's
* fragmented.
* - Call \c lzo_decompress() of the \link compression Data Channel
* Compression module\endlink to decompress the packet if it's
* compressed.
* - Place the resulting packet in \c c->c2.to_tun so that it can be sent
* over the virtual tun/tap network interface to its local destination
* by the \link internal_multiplexer Internal Multiplexer\endlink.
*
* @param c - The context structure of the VPN tunnel associated with the
* packet.
*/
void process_incoming_link (struct context *c);
/**
* Write a packet to the external network interface.
* @ingroup external_multiplexer
*
* This function writes the packet stored in \c c->c2.to_link to the
* external network device contained within \c c->c1.link_socket.
*
* If an error occurs, it is logged and the packet is dropped.
*
* @param c - The context structure of the VPN tunnel associated with the
* packet.
*/
void process_outgoing_link (struct context *c);
/**************************************************************************/
/**
* Read a packet from the virtual tun/tap network interface.
* @ingroup internal_multiplexer
*
* This function reads a packet from the virtual tun/tap network device \c
* c->c1.tuntap and stores it in \c c->c2.buf.
*
* If an error occurs, it is logged and the packet is dropped.
*
* @param c - The context structure in which to store the received
* packet.
*/
void read_incoming_tun (struct context *c);
/**
* Process a packet read from the virtual tun/tap network interface.
* @ingroup internal_multiplexer
*
* This function calls \c encrypt_sign() of the \link data_control Data
* Channel Control module\endlink to process the packet.
*
* If an error occurs, it is logged and the packet is dropped.
*
* @param c - The context structure of the VPN tunnel associated with the
* packet.
*/
void process_incoming_tun (struct context *c);
/**
* Write a packet to the virtual tun/tap network interface.
* @ingroup internal_multiplexer
*
* This function writes the packet stored in \c c->c2.to_tun to the
* virtual tun/tap network device \c c->c1.tuntap.
*
* If an error occurs, it is logged and the packet is dropped.
*
* @param c - The context structure of the VPN tunnel associated with
* the packet.
*/
void process_outgoing_tun (struct context *c);
/**************************************************************************/
bool send_control_channel_string (struct context *c, const char *str, int msglevel);
#define PIPV4_PASSTOS (1<<0)
#define PIPV4_MSSFIX (1<<1)
#define PIPV4_OUTGOING (1<<2)
#define PIPV4_EXTRACT_DHCP_ROUTER (1<<3)
#define PIPV4_CLIENT_NAT (1<<4)
void process_ipv4_header (struct context *c, unsigned int flags, struct buffer *buf);
#if P2MP
void schedule_exit (struct context *c, const int n_seconds, const int signal);
#endif
#endif /* FORWARD_H */
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