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Diffstat (limited to 'src/openvpn/forward.h')
| -rw-r--r-- | src/openvpn/forward.h | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/src/openvpn/forward.h b/src/openvpn/forward.h new file mode 100644 index 0000000..0f829bd --- /dev/null +++ b/src/openvpn/forward.h @@ -0,0 +1,242 @@ +/* + * 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 */ |