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/*
* Off-the-Record Messaging library
* Copyright (C) 2004-2008 Ian Goldberg, Chris Alexander, Nikita Borisov
* <otr@cypherpunks.ca>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of version 2.1 of the GNU Lesser General
* Public License as published by the Free Software Foundation.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __CONTEXT_H__
#define __CONTEXT_H__
#include <gcrypt.h>
#include "dh.h"
#include "auth.h"
#include "sm.h"
typedef enum {
OTRL_MSGSTATE_PLAINTEXT, /* Not yet started an encrypted
conversation */
OTRL_MSGSTATE_ENCRYPTED, /* Currently in an encrypted
conversation */
OTRL_MSGSTATE_FINISHED /* The remote side has sent us a
notification that he has ended
his end of the encrypted
conversation; prevent any
further messages from being
sent to him. */
} OtrlMessageState;
typedef struct s_fingerprint {
struct s_fingerprint *next; /* The next fingerprint in the list */
struct s_fingerprint **tous; /* A pointer to the pointer to us */
unsigned char *fingerprint; /* The fingerprint, or NULL */
struct context *context; /* The context to which we belong */
char *trust; /* The trust level of the fingerprint */
} Fingerprint;
typedef struct context {
struct context * next; /* Linked list pointer */
struct context ** tous; /* A pointer to the pointer to us */
char * username; /* The user this context is for */
char * accountname; /* The username is relative to
this account... */
char * protocol; /* ... and this protocol */
char *fragment; /* The part of the fragmented message
we've seen so far */
size_t fragment_len; /* The length of fragment */
unsigned short fragment_n; /* The total number of fragments
in this message */
unsigned short fragment_k; /* The highest fragment number
we've seen so far for this
message */
OtrlMessageState msgstate; /* The state of message disposition
with this user */
OtrlAuthInfo auth; /* The state of ongoing
authentication with this user */
Fingerprint fingerprint_root; /* The root of a linked list of
Fingerprints entries */
Fingerprint *active_fingerprint; /* Which fingerprint is in use now?
A pointer into the above list */
unsigned int their_keyid; /* current keyid used by other side;
this is set to 0 if we get a
OTRL_TLV_DISCONNECTED message from
them. */
gcry_mpi_t their_y; /* Y[their_keyid] (their DH pubkey) */
gcry_mpi_t their_old_y; /* Y[their_keyid-1] (their prev DH
pubkey) */
unsigned int our_keyid; /* current keyid used by us */
DH_keypair our_dh_key; /* DH key[our_keyid] */
DH_keypair our_old_dh_key; /* DH key[our_keyid-1] */
DH_sesskeys sesskeys[2][2]; /* sesskeys[i][j] are the session keys
derived from DH key[our_keyid-i]
and mpi Y[their_keyid-j] */
unsigned char sessionid[20]; /* The sessionid and bold half */
size_t sessionid_len; /* determined when this private */
OtrlSessionIdHalf sessionid_half; /* connection was established. */
unsigned int protocol_version; /* The version of OTR in use */
unsigned char *preshared_secret; /* A secret you share with this
user, in order to do
authentication. */
size_t preshared_secret_len; /* The length of the above secret. */
/* saved mac keys to be revealed later */
unsigned int numsavedkeys;
unsigned char *saved_mac_keys;
/* generation number: increment every time we go private, and never
* reset to 0 (unless we remove the context entirely) */
unsigned int generation;
time_t lastsent; /* The last time a Data Message was sent */
char *lastmessage; /* The plaintext of the last Data Message sent */
int may_retransmit; /* Is the last message eligible for
retransmission? */
enum {
OFFER_NOT,
OFFER_SENT,
OFFER_REJECTED,
OFFER_ACCEPTED
} otr_offer; /* Has this correspondent repsponded to our
OTR offers? */
/* Application data to be associated with this context */
void *app_data;
/* A function to free the above data when we forget this context */
void (*app_data_free)(void *);
OtrlSMState *smstate; /* The state of the current
socialist millionaires exchange */
} ConnContext;
#include "userstate.h"
ConnContext * otrl_context_new(const char * user, const char * accountname,
const char * protocol);
/* Look up a connection context by name/account/protocol from the given
* OtrlUserState. If add_if_missing is true, allocate and return a new
* context if one does not currently exist. In that event, call
* add_app_data(data, context) so that app_data and app_data_free can be
* filled in by the application, and set *addedp to 1. */
ConnContext * otrl_context_find(OtrlUserState us, const char *user,
const char *accountname, const char *protocol, int add_if_missing,
int *addedp,
void (*add_app_data)(void *data, ConnContext *context), void *data);
/* Find a fingerprint in a given context, perhaps adding it if not
* present. */
Fingerprint *otrl_context_find_fingerprint(ConnContext *context,
unsigned char fingerprint[20], int add_if_missing, int *addedp);
/* Set the trust level for a given fingerprint */
void otrl_context_set_trust(Fingerprint *fprint, const char *trust);
/* Set the preshared secret for a given fingerprint. Note that this
* currently only stores the secret in the ConnContext structure, but
* doesn't yet do anything with it. */
void otrl_context_set_preshared_secret(ConnContext *context,
const unsigned char *secret, size_t secret_len);
/* Force a context into the OTRL_MSGSTATE_FINISHED state. */
void otrl_context_force_finished(ConnContext *context);
/* Force a context into the OTRL_MSGSTATE_PLAINTEXT state. */
void otrl_context_force_plaintext(ConnContext *context);
/* Forget a fingerprint (so long as it's not the active one. If it's a
* fingerprint_root, forget the whole context (as long as
* and_maybe_context is set, and it's PLAINTEXT). Also, if it's not
* the fingerprint_root, but it's the only fingerprint, and we're
* PLAINTEXT, forget the whole context if and_maybe_context is set. */
void otrl_context_forget_fingerprint(Fingerprint *fprint,
int and_maybe_context);
/* Forget a whole context, so long as it's PLAINTEXT. */
void otrl_context_forget(ConnContext *context);
/* Forget all the contexts in a given OtrlUserState. */
void otrl_context_forget_all(OtrlUserState us);
#endif
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