/*
  *  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
  */
 

 #define OPENVPN_PLUGIN_VERSION 2
 

 /*
  * Plug-in types.  These types correspond to the set of script callbacks
  * supported by OpenVPN.

  *
  * This is the general call sequence to expect when running in server mode:
  *
  * Initial Server Startup:
  *
  * FUNC: openvpn_plugin_open_v1
  * FUNC: openvpn_plugin_client_constructor_v1 (this is the top-level "generic"
  *                                             client template)
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_UP
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ROUTE_UP
  *
  * New Client Connection:
  *
  * FUNC: openvpn_plugin_client_constructor_v1

  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ENABLE_PF

  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_VERIFY (called once for every cert

  *                                                     in the server chain)

  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY

  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_FINAL
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_IPCHANGE
  *

  * [If OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY returned OPENVPN_PLUGIN_FUNC_DEFERRED,

  * we don't proceed until authentication is verified via auth_control_file]
  *
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_CLIENT_CONNECT_V2
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_LEARN_ADDRESS
  * 
  * [Client session ensues]
  *
  * For each "TLS soft reset", according to reneg-sec option (or similar):
  *

  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ENABLE_PF
  *
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_VERIFY (called once for every cert

  *                                                     in the server chain)

  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY

  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_FINAL
  * 

  * [If OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY returned OPENVPN_PLUGIN_FUNC_DEFERRED,

  * we expect that authentication is verified via auth_control_file within
  * the number of seconds defined by the "hand-window" option.  Data channel traffic
  * will continue to flow uninterrupted during this period.]
  *
  * [Client session continues]
  *
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_CLIENT_DISCONNECT

  * FUNC: openvpn_plugin_client_destructor_v1

  *
  * [ some time may pass ]
  *
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_LEARN_ADDRESS (this coincides with a
  *                                                            lazy free of initial
  *                                                            learned addr object)
  * Server Shutdown:
  *
  * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_DOWN
  * FUNC: openvpn_plugin_client_destructor_v1 (top-level "generic" client)
  * FUNC: openvpn_plugin_close_v1

  */
 #define OPENVPN_PLUGIN_UP                    0
 #define OPENVPN_PLUGIN_DOWN                  1
 #define OPENVPN_PLUGIN_ROUTE_UP              2
 #define OPENVPN_PLUGIN_IPCHANGE              3
 #define OPENVPN_PLUGIN_TLS_VERIFY            4
 #define OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY 5
 #define OPENVPN_PLUGIN_CLIENT_CONNECT        6
 #define OPENVPN_PLUGIN_CLIENT_DISCONNECT     7
 #define OPENVPN_PLUGIN_LEARN_ADDRESS         8

 #define OPENVPN_PLUGIN_CLIENT_CONNECT_V2     9

 #define OPENVPN_PLUGIN_TLS_FINAL             10

 #define OPENVPN_PLUGIN_ENABLE_PF             11
 #define OPENVPN_PLUGIN_N                     12

 
 /*
  * Build a mask out of a set of plug-in types.
  */
 #define OPENVPN_PLUGIN_MASK(x) (1<<(x))
 
 /*
  * A pointer to a plugin-defined object which contains
  * the object state.
  */
 typedef void *openvpn_plugin_handle_t;
 
 /*
  * Return value for openvpn_plugin_func_v1 function
  */
 #define OPENVPN_PLUGIN_FUNC_SUCCESS  0
 #define OPENVPN_PLUGIN_FUNC_ERROR    1

 #define OPENVPN_PLUGIN_FUNC_DEFERRED 2

 
 /*
  * For Windows (needs to be modified for MSVC)
  */
 #if defined(__MINGW32_VERSION) && !defined(OPENVPN_PLUGIN_H)
 # define OPENVPN_EXPORT __declspec(dllexport)
 #else
 # define OPENVPN_EXPORT
 #endif
 
 /*
  * If OPENVPN_PLUGIN_H is defined, we know that we are being
  * included in an OpenVPN compile, rather than a plugin compile.
  */
 #ifdef OPENVPN_PLUGIN_H
 
 /*
  * We are compiling OpenVPN.
  */
 #define OPENVPN_PLUGIN_DEF        typedef
 #define OPENVPN_PLUGIN_FUNC(name) (*name)
 
 #else
 
 /*
  * We are compiling plugin.
  */
 #define OPENVPN_PLUGIN_DEF        OPENVPN_EXPORT
 #define OPENVPN_PLUGIN_FUNC(name) name
 
 #endif
 
 /*

  * Used by openvpn_plugin_func to return structured
  * data.  The plugin should allocate all structure
  * instances, name strings, and value strings with
  * malloc, since OpenVPN will assume that it
  * can free the list by calling free() over the same.
  */
 struct openvpn_plugin_string_list
 {
   struct openvpn_plugin_string_list *next;
   char *name;
   char *value;
 };
 
 /*

  * Multiple plugin modules can be cascaded, and modules can be
  * used in tandem with scripts.  The order of operation is that
  * the module func() functions are called in the order that
  * the modules were specified in the config file.  If a script
  * was specified as well, it will be called last.  If the
  * return code of the module/script controls an authentication
  * function (such as tls-verify or auth-user-pass-verify), then
  * every module and script must return success (0) in order for
  * the connection to be authenticated.
  *
  * Notes:
  *
  * Plugins which use a privilege-separation model (by forking in
  * their initialization function before the main OpenVPN process
  * downgrades root privileges and/or executes a chroot) must
  * daemonize after a fork if the "daemon" environmental variable is
  * set.  In addition, if the "daemon_log_redirect" variable is set,
  * the plugin should preserve stdout/stderr across the daemon()
  * syscall.  See the daemonize() function in plugin/auth-pam/auth-pam.c
  * for an example.
  */
 
 /*
  * Prototypes for functions which OpenVPN plug-ins must define.
  */
 
 /*

  * FUNCTION: openvpn_plugin_open_v2

  *
  * REQUIRED: YES
  * 
  * Called on initial plug-in load.  OpenVPN will preserve plug-in state
  * across SIGUSR1 restarts but not across SIGHUP restarts.  A SIGHUP reset
  * will cause the plugin to be closed and reopened.
  *
  * ARGUMENTS
  *
  * *type_mask : Set by OpenVPN to the logical OR of all script
  *              types which this version of OpenVPN supports.  The plug-in
  *              should set this value to the logical OR of all script types
  *              which the plug-in wants to intercept.  For example, if the
  *              script wants to intercept the client-connect and
  *              client-disconnect script types:
  *
  *              *type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_CONNECT)
  *                         | OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_DISCONNECT)
  *
  * argv : a NULL-terminated array of options provided to the OpenVPN
  *        "plug-in" directive.  argv[0] is the dynamic library pathname.
  *
  * envp : a NULL-terminated array of OpenVPN-set environmental
  *        variables in "name=value" format.  Note that for security reasons,
  *        these variables are not actually written to the "official"
  *        environmental variable store of the process.
  *

  * return_list : used to return data back to OpenVPN.
  *

  * RETURN VALUE
  *
  * An openvpn_plugin_handle_t value on success, NULL on failure
  */

 OPENVPN_PLUGIN_DEF openvpn_plugin_handle_t OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v2)
      (unsigned int *type_mask,
       const char *argv[],
       const char *envp[],
       struct openvpn_plugin_string_list **return_list);

 
 /*

  * FUNCTION: openvpn_plugin_func_v2

  *
  * Called to perform the work of a given script type.
  *
  * REQUIRED: YES
  * 
  * ARGUMENTS
  *
  * handle : the openvpn_plugin_handle_t value which was returned by

  *          openvpn_plugin_open.

  *
  * type : one of the PLUGIN_x types
  *
  * argv : a NULL-terminated array of "command line" options which
  *        would normally be passed to the script.  argv[0] is the dynamic
  *        library pathname.
  *
  * envp : a NULL-terminated array of OpenVPN-set environmental
  *        variables in "name=value" format.  Note that for security reasons,
  *        these variables are not actually written to the "official"
  *        environmental variable store of the process.
  *

  * per_client_context : the per-client context pointer which was returned by
  *        openvpn_plugin_client_constructor_v1, if defined.
  *
  * return_list : used to return data back to OpenVPN.
  *

  * RETURN VALUE
  *
  * OPENVPN_PLUGIN_FUNC_SUCCESS on success, OPENVPN_PLUGIN_FUNC_ERROR on failure

  *
  * In addition, OPENVPN_PLUGIN_FUNC_DEFERRED may be returned by
  * OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY.  This enables asynchronous
  * authentication where the plugin (or one of its agents) may indicate
  * authentication success/failure some number of seconds after the return
  * of the OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY handler by writing a single
  * char to the file named by auth_control_file in the environmental variable
  * list (envp).
  *
  * first char of auth_control_file:
  * '0' -- indicates auth failure
  * '1' -- indicates auth success
  *
  * OpenVPN will delete the auth_control_file after it goes out of scope.
  *

  * If an OPENVPN_PLUGIN_ENABLE_PF handler is defined and returns success
  * for a particular client instance, packet filtering will be enabled for that
  * instance.  OpenVPN will then attempt to read the packet filter configuration
  * from the temporary file named by the environmental variable pf_file.  This
  * file may be generated asynchronously and may be dynamically updated during the
  * client session, however the client will be blocked from sending or receiving
  * VPN tunnel packets until the packet filter file has been generated.  OpenVPN
  * will periodically test the packet filter file over the life of the client
  * instance and reload when modified.  OpenVPN will delete the packet filter file
  * when the client instance goes out of scope.
  *
  * Packet filter file grammar:
  *
  * [CLIENTS DROP|ACCEPT]
  * {+|-}common_name1
  * {+|-}common_name2
  * . . .
  * [SUBNETS DROP|ACCEPT]
  * {+|-}subnet1
  * {+|-}subnet2
  * . . .
  * [END]
  *
  * Subnet: IP-ADDRESS | IP-ADDRESS/NUM_NETWORK_BITS
  *
  * CLIENTS refers to the set of clients (by their common-name) which
  * this instance is allowed ('+') to connect to, or is excluded ('-')
  * from connecting to.  Note that in the case of client-to-client
  * connections, such communication must be allowed by the packet filter
  * configuration files of both clients.
  *
  * SUBNETS refers to IP addresses or IP address subnets which this
  * instance may connect to ('+') or is excluded ('-') from connecting
  * to.
  *
  * DROP or ACCEPT defines default policy when there is no explicit match
  * for a common-name or subnet.  The [END] tag must exist.  A special
  * purpose tag called [KILL] will immediately kill the client instance.
  * A given client or subnet rule applies to both incoming and outgoing
  * packets.
  *

  * See plugin/defer/simple.c for an example on using asynchronous

  * authentication and client-specific packet filtering.

  */

 OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v2)
      (openvpn_plugin_handle_t handle,
       const int type,
       const char *argv[],
       const char *envp[],
       void *per_client_context,
       struct openvpn_plugin_string_list **return_list);

 
 /*
  * FUNCTION: openvpn_plugin_close_v1
  *
  * REQUIRED: YES
  * 
  * ARGUMENTS
  *
  * handle : the openvpn_plugin_handle_t value which was returned by

  *          openvpn_plugin_open.

  *
  * Called immediately prior to plug-in unload.
  */
 OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_close_v1)
      (openvpn_plugin_handle_t handle);
 
 /*
  * FUNCTION: openvpn_plugin_abort_v1
  *
  * REQUIRED: NO
  * 
  * ARGUMENTS
  *
  * handle : the openvpn_plugin_handle_t value which was returned by

  *          openvpn_plugin_open.

  *
  * Called when OpenVPN is in the process of aborting due to a fatal error.
  * Will only be called on an open context returned by a prior successful

  * openvpn_plugin_open callback.

  */
 OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_abort_v1)
      (openvpn_plugin_handle_t handle);

 
 /*
  * FUNCTION: openvpn_plugin_client_constructor_v1
  *
  * Called to allocate a per-client memory region, which
  * is then passed to the openvpn_plugin_func_v2 function.
  * This function is called every time the OpenVPN server
  * constructs a client instance object, which normally
  * occurs when a session-initiating packet is received
  * by a new client, even before the client has authenticated.
  *
  * This function should allocate the private memory needed
  * by the plugin to track individual OpenVPN clients, and
  * return a void * to this memory region.
  *
  * REQUIRED: NO
  * 
  * ARGUMENTS
  *
  * handle : the openvpn_plugin_handle_t value which was returned by
  *          openvpn_plugin_open.
  *
  * RETURN VALUE
  *
  * void * pointer to plugin's private per-client memory region, or NULL
  * if no memory region is required.
  */
 OPENVPN_PLUGIN_DEF void * OPENVPN_PLUGIN_FUNC(openvpn_plugin_client_constructor_v1)
      (openvpn_plugin_handle_t handle);
 
 /*
  * FUNCTION: openvpn_plugin_client_destructor_v1
  *
  * This function is called on client instance object destruction.
  *
  * REQUIRED: NO
  * 
  * ARGUMENTS
  *
  * handle : the openvpn_plugin_handle_t value which was returned by
  *          openvpn_plugin_open.
  *
  * per_client_context : the per-client context pointer which was returned by
  *        openvpn_plugin_client_constructor_v1, if defined.
  */
 OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_client_destructor_v1)
      (openvpn_plugin_handle_t handle, void *per_client_context);
 
 /*

  * FUNCTION: openvpn_plugin_select_initialization_point_v1
  *
  * Several different points exist in OpenVPN's initialization sequence where
  * the openvpn_plugin_open function can be called.  While the default is
  * OPENVPN_PLUGIN_INIT_PRE_DAEMON, this function can be used to select a
  * different initialization point.  For example, if your plugin needs to
  * return configuration parameters to OpenVPN, use
  * OPENVPN_PLUGIN_INIT_PRE_CONFIG_PARSE.
  *
  * REQUIRED: NO
  * 
  * RETURN VALUE:
  *
  * An OPENVPN_PLUGIN_INIT_x value.
  */
 #define OPENVPN_PLUGIN_INIT_PRE_CONFIG_PARSE 1
 #define OPENVPN_PLUGIN_INIT_PRE_DAEMON       2 /* default */
 #define OPENVPN_PLUGIN_INIT_POST_DAEMON      3
 #define OPENVPN_PLUGIN_INIT_POST_UID_CHANGE  4
 
 OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_select_initialization_point_v1)
      (void);
 
 /*

  * FUNCTION: openvpn_plugin_min_version_required_v1
  *
  * This function is called by OpenVPN to query the minimum
    plugin interface version number required by the plugin.
  *
  * REQUIRED: NO
  * 
  * RETURN VALUE
  *
  * The minimum OpenVPN plugin interface version number necessary to support
  * this plugin.
  */
 OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_min_version_required_v1)
      (void);
 
 /*
  * Deprecated functions which are still supported for backward compatibility.
  */
 
 OPENVPN_PLUGIN_DEF openvpn_plugin_handle_t OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v1)
      (unsigned int *type_mask,
       const char *argv[],
       const char *envp[]);
 
 OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v1)
      (openvpn_plugin_handle_t handle, const int type, const char *argv[], const char *envp[]);