/*
  *  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) 2002-2018 OpenVPN Inc <sales@openvpn.net>
  *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>

  *
  *  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; if not, write to the Free Software Foundation, Inc.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

  */
 
 /**
  * @file Control Channel Common Data Structures
  */
 
 #ifndef SSL_COMMON_H_
 #define SSL_COMMON_H_
 
 #include "session_id.h"
 #include "socket.h"
 #include "packet_id.h"
 #include "crypto.h"
 #include "options.h"
 
 #include "ssl_backend.h"
 

 /* passwords */
 #define UP_TYPE_AUTH        "Auth"
 #define UP_TYPE_PRIVATE_KEY "Private Key"
 

 /** @addtogroup control_processor
  *  @{ */
 /**
  * @name Control channel negotiation states
  *
  * These states represent the different phases of control channel
  * negotiation between OpenVPN peers.  OpenVPN servers and clients
  * progress through the states in a different order, because of their
  * different roles during exchange of random material.  The references to
  * the \c key_source2 structure in the list below is only valid if %key
  * method 2 is being used.  See the \link key_generation data channel key
  * generation\endlink related page for more information.
  *
  * Clients follow this order:
  *   -# \c S_INITIAL, ready to begin three-way handshake and control
  *      channel negotiation.
  *   -# \c S_PRE_START, have started three-way handshake, waiting for
  *      acknowledgment from remote.
  *   -# \c S_START, initial three-way handshake complete.
  *   -# \c S_SENT_KEY, have sent local part of \c key_source2 random
  *      material.
  *   -# \c S_GOT_KEY, have received remote part of \c key_source2 random
  *      material.
  *   -# \c S_ACTIVE, normal operation during remaining handshake window.
  *   -# \c S_NORMAL_OP, normal operation.
  *
  * Servers follow the same order, except for \c S_SENT_KEY and \c
  * S_GOT_KEY being reversed, because the server first receives the
  * client's \c key_source2 random material before generating and sending
  * its own.
  *
  * @{
  */
 #define S_ERROR          -1     /**< Error state.  */
 #define S_UNDEF           0     /**< Undefined state, used after a \c
                                  *   key_state is cleaned up. */
 #define S_INITIAL         1     /**< Initial \c key_state state after
                                  *   initialization by \c key_state_init()
                                  *   before start of three-way handshake. */
 #define S_PRE_START       2     /**< Waiting for the remote OpenVPN peer
                                  *   to acknowledge during the initial
                                  *   three-way handshake. */
 #define S_START           3     /**< Three-way handshake is complete,
                                  *   start of key exchange. */
 #define S_SENT_KEY        4     /**< Local OpenVPN process has sent its
                                  *   part of the key material. */
 #define S_GOT_KEY         5     /**< Local OpenVPN process has received
                                  *   the remote's part of the key
                                  *   material. */
 #define S_ACTIVE          6     /**< Operational \c key_state state
                                  *   immediately after negotiation has
                                  *   completed while still within the
                                  *   handshake window. */
 /* ready to exchange data channel packets */
 #define S_NORMAL_OP       7     /**< Normal operational \c key_state
                                  *   state. */
 /** @} name Control channel negotiation states */
 /** @} addtogroup control_processor */
 

 /**
  * Container for one half of random material to be used in %key method 2
  * \ref key_generation "data channel key generation".
  * @ingroup control_processor
  */
 struct key_source {

     uint8_t pre_master[48];     /**< Random used for master secret

                                  *   generation, provided only by client
                                  *   OpenVPN peer. */

     uint8_t random1[32];        /**< Seed used for master secret

                                  *   generation, provided by both client
                                  *   and server. */

     uint8_t random2[32];        /**< Seed used for key expansion, provided

                                  *   by both client and server. */
 };
 
 
 /**
  * Container for both halves of random material to be used in %key method
  * 2 \ref key_generation "data channel key generation".
  * @ingroup control_processor
  */
 struct key_source2 {

     struct key_source client;   /**< Random provided by client. */
     struct key_source server;   /**< Random provided by server. */

 };
 
 /**
  * Security parameter state of one TLS and data channel %key session.
  * @ingroup control_processor
  *
  * This structure represents one security parameter session between
  * OpenVPN peers.  It includes the control channel TLS state and the data
  * channel crypto state.  It also contains the reliability layer
  * structures used for control channel messages.
  *
  * A new \c key_state structure is initialized for each hard or soft
  * reset.
  *
  * @see
  *  - This structure should be initialized using the \c key_state_init()
  *    function.
  *  - This structure should be cleaned up using the \c key_state_free()
  *    function.
  */
 struct key_state
 {

     int state;

     /**
      * Key id for this key_state,  inherited from struct tls_session.
      * @see tls_session::key_id.
      */
     int key_id;

     struct key_state_ssl ks_ssl; /* contains SSL object and BIOs for the control channel */

     time_t established;         /* when our state went S_ACTIVE */
     time_t must_negotiate;      /* key negotiation times out if not finished before this time */
     time_t must_die;            /* this object is destroyed at this time */

     int initial_opcode;         /* our initial P_ opcode */
     struct session_id session_id_remote; /* peer's random session ID */
     struct link_socket_actual remote_addr; /* peer's IP addr */

     struct crypto_options crypto_options;/* data channel crypto options */

     struct key_source2 *key_src;       /* source entropy for key expansion */

     struct buffer plaintext_read_buf;
     struct buffer plaintext_write_buf;
     struct buffer ack_write_buf;

     struct reliable *send_reliable; /* holds a copy of outgoing packets until ACK received */
     struct reliable *rec_reliable; /* order incoming ciphertext packets before we pass to TLS */
     struct reliable_ack *rec_ack; /* buffers all packet IDs we want to ACK back to sender */

     struct buffer_list *paybuf;

     counter_type n_bytes;                /* how many bytes sent/recvd since last key exchange */
     counter_type n_packets;              /* how many packets sent/recvd since last key exchange */

     /*
      * If bad username/password, TLS connection will come up but 'authenticated' will be false.
      */
     bool authenticated;
     time_t auth_deferred_expire;

 
 #ifdef ENABLE_DEF_AUTH

     /* If auth_deferred is true, authentication is being deferred */
     bool auth_deferred;

 #ifdef MANAGEMENT_DEF_AUTH

     unsigned int mda_key_id;
     unsigned int mda_status;

 #endif
 #ifdef PLUGIN_DEF_AUTH

     unsigned int auth_control_status;
     time_t acf_last_mod;
     char *auth_control_file;

 #endif
 #endif
 };
 

 /** Control channel wrapping (--tls-auth/--tls-crypt) context */
 struct tls_wrap_ctx
 {

     enum {
         TLS_WRAP_NONE = 0, /**< No control channel wrapping */
         TLS_WRAP_AUTH,  /**< Control channel authentication */
         TLS_WRAP_CRYPT, /**< Control channel encryption and authentication */
     } mode;                     /**< Control channel wrapping mode */
     struct crypto_options opt;  /**< Crypto state */
     struct buffer work;         /**< Work buffer (only for --tls-crypt) */

     struct key_ctx tls_crypt_v2_server_key;  /**< Decrypts client keys */
     const struct buffer *tls_crypt_v2_wkc;   /**< Wrapped client key,
                                                   sent to server */
     struct buffer tls_crypt_v2_metadata;     /**< Received from client */
     bool cleanup_key_ctx;                    /**< opt.key_ctx_bi is owned by
                                                   this context */

 };
 

 /*
  * Our const options, obtained directly or derived from
  * command line options.
  */
 struct tls_options
 {

     /* our master TLS context from which all SSL objects derived */
     struct tls_root_ctx ssl_ctx;

     /* data channel cipher, hmac, and key lengths */
     struct key_type key_type;

     /* true if we are a TLS server, client otherwise */
     bool server;

     /* if true, don't xmit until first packet from peer is received */
     bool xmit_hold;

 
 #ifdef ENABLE_OCC

     /* local and remote options strings
      * that must match between client and server */
     const char *local_options;
     const char *remote_options;

 #endif
 

     /* from command line */
     int key_method;
     bool replay;
     bool single_session;

 #ifdef ENABLE_OCC

     bool disable_occ;

 #endif

     int mode;
     bool pull;
     int push_peer_info_detail;
     int transition_window;
     int handshake_window;
     interval_t packet_timeout;
     int renegotiate_bytes;
     int renegotiate_packets;
     interval_t renegotiate_seconds;
 
     /* cert verification parms */
     const char *verify_command;
     const char *verify_export_cert;
     int verify_x509_type;
     const char *verify_x509_name;
     const char *crl_file;
     const char *crl_file_inline;
     int ns_cert_type;
     unsigned remote_cert_ku[MAX_PARMS];
     const char *remote_cert_eku;
     uint8_t *verify_hash;

     hash_algo_type verify_hash_algo;

     char *x509_username_field;
 
     /* allow openvpn config info to be
      * passed over control channel */
     bool pass_config_info;
 
     /* struct crypto_option flags */
     unsigned int crypto_flags;
 
     int replay_window;                 /* --replay-window parm */
     int replay_time;                   /* --replay-window parm */
     bool tcp_mode;
 
     const char *config_ciphername;
     const char *config_authname;
     bool ncp_enabled;
 

     bool tls_crypt_v2;

     const char *tls_crypt_v2_verify_script;

     /** TLS handshake wrapping state */
     struct tls_wrap_ctx tls_wrap;
 
     /* frame parameters for TLS control channel */
     struct frame frame;
 
     /* used for username/password authentication */
     const char *auth_user_pass_verify_script;
     bool auth_user_pass_verify_script_via_file;
     const char *tmp_dir;
     const char *auth_user_pass_file;
     bool auth_token_generate;   /**< Generate auth-tokens on successful user/pass auth,

                                  *   set via options->auth_token_generate. */

     unsigned int auth_token_lifetime;

     /* use the client-config-dir as a positive authenticator */
     const char *client_config_dir_exclusive;

     /* instance-wide environment variable set */
     struct env_set *es;
     const struct plugin_list *plugins;

     /* compression parms */

 #ifdef USE_COMP

     struct compress_options comp_options;

 #endif
 

     /* configuration file SSL-related boolean and low-permutation options */
 #define SSLF_CLIENT_CERT_NOT_REQUIRED (1<<0)
 #define SSLF_CLIENT_CERT_OPTIONAL     (1<<1)
 #define SSLF_USERNAME_AS_COMMON_NAME  (1<<2)
 #define SSLF_AUTH_USER_PASS_OPTIONAL  (1<<3)
 #define SSLF_OPT_VERIFY               (1<<4)
 #define SSLF_CRL_VERIFY_DIR           (1<<5)
 #define SSLF_TLS_VERSION_MIN_SHIFT    6
 #define SSLF_TLS_VERSION_MIN_MASK     0xF  /* (uses bit positions 6 to 9) */
 #define SSLF_TLS_VERSION_MAX_SHIFT    10
 #define SSLF_TLS_VERSION_MAX_MASK     0xF  /* (uses bit positions 10 to 13) */
     unsigned int ssl_flags;

 
 #ifdef MANAGEMENT_DEF_AUTH

     struct man_def_auth_context *mda_context;

 #endif
 

     const struct x509_track *x509_track;

 #ifdef ENABLE_MANAGEMENT

     const struct static_challenge_info *sci;

 #endif
 

     /* --gremlin bits */
     int gremlin;

     /* Keying Material Exporter [RFC 5705] parameters */
     const char *ekm_label;
     size_t ekm_label_size;
     size_t ekm_size;

 };
 

 /** @addtogroup control_processor
  *  @{ */
 /** @name Index of key_state objects within a tls_session structure
  *
  *  This is the index of \c tls_session.key
  *
  *  @{ */
 #define KS_PRIMARY    0         /**< Primary %key state index. */
 #define KS_LAME_DUCK  1         /**< %Key state index that will retire
                                  *   soon. */
 #define KS_SIZE       2         /**< Size of the \c tls_session.key array. */
 /** @} name Index of key_state objects within a tls_session structure */
 /** @} addtogroup control_processor */
 

 #define AUTH_TOKEN_SIZE 32      /**< Size of server side generated auth tokens.
                                  *   32 bytes == 256 bits
                                  */

 
 /**
  * Security parameter state of a single session within a VPN tunnel.
  * @ingroup control_processor
  *
  * This structure represents an OpenVPN peer-to-peer control channel
  * session.
  *
  * A \c tls_session remains over soft resets, but a new instance is
  * initialized for each hard reset.
  *
  * @see
  *  - This structure should be initialized using the \c tls_session_init()
  *    function.
  *  - This structure should be cleaned up using the \c tls_session_free()
  *    function.
  */
 struct tls_session
 {

     /* const options and config info */
     struct tls_options *opt;

     /* during hard reset used to control burst retransmit */
     bool burst;

     /* authenticate control packets */
     struct tls_wrap_ctx tls_wrap;

     int initial_opcode;         /* our initial P_ opcode */
     struct session_id session_id; /* our random session ID */

     /**
      * The current active key id, used to keep track of renegotiations.
      * key_id increments with each soft reset to KEY_ID_MASK then recycles back
      * to 1.  This way you know that if key_id is 0, it is the first key.
      */
     int key_id;

     int limit_next;             /* used for traffic shaping on the control channel */

     int verify_maxlevel;

     char *common_name;

     struct cert_hash_set *cert_hash_set;

 
 #ifdef ENABLE_PF

     uint32_t common_name_hashval;

 #endif
 

     bool verified;              /* true if peer certificate was verified against CA */

     /* not-yet-authenticated incoming client */
     struct link_socket_actual untrusted_addr;

     struct key_state key[KS_SIZE];

 };
 
 /** @addtogroup control_processor
  *  @{ */
 /** @name Index of tls_session objects within a tls_multi structure
  *
  *  This is the index of \c tls_multi.session
  *
  *  Normally three tls_session objects are maintained by an active openvpn
  *  session.  The first is the current, TLS authenticated session, the
  *  second is used to process connection requests from a new client that
  *  would usurp the current session if successfully authenticated, and the
  *  third is used as a repository for a "lame-duck" %key in the event that
  *  the primary session resets due to error while the lame-duck %key still
  *  has time left before its expiration.  Lame duck keys are used to
  *  maintain the continuity of the data channel connection while a new %key
  *  is being negotiated.
  *
  *  @{ */
 #define TM_ACTIVE    0          /**< Active \c tls_session. */
 #define TM_UNTRUSTED 1          /**< As yet un-trusted \c tls_session
                                  *   being negotiated. */
 #define TM_LAME_DUCK 2          /**< Old \c tls_session. */
 #define TM_SIZE      3          /**< Size of the \c tls_multi.session
                                  *   array. */
 /** @} name Index of tls_session objects within a tls_multi structure */
 /** @} addtogroup control_processor */
 
 
 /*
  * The number of keys we will scan on encrypt or decrypt.  The first
  * is the "active" key.  The second is the lame_duck or retiring key
  * associated with the active key's session ID.  The third is a detached
  * lame duck session that only occurs in situations where a key renegotiate
  * failed on the active key, but a lame duck key was still valid.  By
  * preserving the lame duck session, we can be assured of having a data
  * channel key available even when network conditions are so bad that
  * we can't negotiate a new key within the time allotted.
  */
 #define KEY_SCAN_SIZE 3
 
 
 /**
  * Security parameter state for a single VPN tunnel.
  * @ingroup control_processor
  *
  * An active VPN tunnel running with TLS enabled has one \c tls_multi
  * object, in which it stores all control channel and data channel
  * security parameter state.  This structure can contain multiple,
  * possibly simultaneously active, \c tls_context objects to allow for
  * interruption-less transitions during session renegotiations.  Each \c
  * tls_context represents one control channel session, which can span
  * multiple data channel security parameter sessions stored in \c
  * key_state structures.
  */
 struct tls_multi
 {

     /* used to coordinate access between main thread and TLS thread */
     /*MUTEX_PTR_DEFINE (mutex);*/
 
     /* const options and config info */
     struct tls_options opt;
 
     struct key_state *key_scan[KEY_SCAN_SIZE];
     /**< List of \c key_state objects in the
      *   order they should be scanned by data
      *   channel modules. */
 
     /*
      * used by tls_pre_encrypt to communicate the encrypt key
      * to tls_post_encrypt()
      */
     struct key_state *save_ks;  /* temporary pointer used between pre/post routines */
 
     /*
      * Used to return outgoing address from
      * tls_multi_process.
      */
     struct link_socket_actual to_link_addr;
 
     int n_sessions;             /**< Number of sessions negotiated thus

                                  *   far. */
 

     /*
      * Number of errors.
      */
     int n_hard_errors; /* errors due to TLS negotiation failure */
     int n_soft_errors; /* errors due to unrecognized or failed-to-authenticate incoming packets */

     /*
      * Our locked common name, username, and cert hashes (cannot change during the life of this tls_multi object)
      */
     char *locked_cn;
     char *locked_username;
     struct cert_hash_set *locked_cert_hash_set;

 
 #ifdef ENABLE_DEF_AUTH

     /*
      * An error message to send to client on AUTH_FAILED
      */
     char *client_reason;

     /* Time of last call to tls_authentication_status */
     time_t tas_last;

 #endif
 

 #if P2MP_SERVER

     /*
      * A multi-line string of general-purpose info received from peer
      * over control channel.
      */
     char *peer_info;

 #endif
 

     /* For P_DATA_V2 */
     uint32_t peer_id;
     bool use_peer_id;

     char *remote_ciphername;    /**< cipher specified in peer's config file */

     char *auth_token;    /**< If server sends a generated auth-token,

                           *   this is the token to use for future
                           *   user/pass authentications in this session.
                           */

     time_t auth_token_tstamp; /**< timestamp of the generated token */
     bool auth_token_sent; /**< If server uses --auth-gen-token and
                            *   token has been sent to client */
     /*
      * Our session objects.
      */
     struct tls_session session[TM_SIZE];
     /**< Array of \c tls_session objects
      *   representing control channel
      *   sessions with the remote peer. */

 };
 

 #endif /* SSL_COMMON_H_ */