source: otr.c @ 8bd697c

#include "bitlbee.h"
#ifdef WITH_OTR
#include "irc.h"
#include "otr.h"
#include <sys/types.h>
#include <unistd.h>

/**
files used to store OTR data:
  $configdir/$nick.otr_keys
  $configdir/$nick.otr_fprints
 **/


/** OTR interface routines for the OtrlMessageAppOps struct: **/

OtrlPolicy op_policy(void *opdata, ConnContext *context);

void op_create_privkey(void *opdata, const char *accountname, const char *protocol);

int op_is_logged_in(void *opdata, const char *accountname, const char *protocol,
        const char *recipient);

void op_inject_message(void *opdata, const char *accountname, const char *protocol,
        const char *recipient, const char *message);

int op_display_otr_message(void *opdata, const char *accountname, const char *protocol,
        const char *username, const char *msg);

void op_new_fingerprint(void *opdata, OtrlUserState us, const char *accountname,
        const char *protocol, const char *username, unsigned char fingerprint[20]);

void op_write_fingerprints(void *opdata);

void op_gone_secure(void *opdata, ConnContext *context);

void op_gone_insecure(void *opdata, ConnContext *context);

void op_still_secure(void *opdata, ConnContext *context, int is_reply);

void op_log_message(void *opdata, const char *message);

int op_max_message_size(void *opdata, ConnContext *context);

const char *op_account_name(void *opdata, const char *account, const char *protocol);


/** otr sub-command handlers: **/

void cmd_otr_connect(irc_t *irc, char **args);
void cmd_otr_disconnect(irc_t *irc, char **args);
void cmd_otr_smp(irc_t *irc, char **args);
void cmd_otr_trust(irc_t *irc, char **args);
void cmd_otr_info(irc_t *irc, char **args);
void cmd_otr_keygen(irc_t *irc, char **args);
void cmd_otr_forget(irc_t *irc, char **args);

const command_t otr_commands[] = {
        { "connect",     1, &cmd_otr_connect,    0 },
        { "disconnect",  1, &cmd_otr_disconnect, 0 },
        { "smp",         2, &cmd_otr_smp,        0 },
        { "trust",       6, &cmd_otr_trust,      0 },
        { "info",        0, &cmd_otr_info,       0 },
        { "keygen",      1, &cmd_otr_keygen,     0 },
        { "forget",      2, &cmd_otr_forget,     0 },
        { NULL }
};


/** misc. helpers/subroutines: **/

/* start background thread to generate a (new) key for a given account */
void otr_keygen(irc_t *irc, const char *handle, const char *protocol);

/* keygen thread main func */
gpointer otr_keygen_thread_func(gpointer data);

/* mainloop handler for when keygen thread finishes */
gboolean keygen_finish_handler(gpointer data, gint fd, b_input_condition cond);

/* data to be passed to otr_keygen_thread_func */
struct kgdata {
        irc_t *irc;            /* access to OTR userstate */
        char *keyfile;         /* free me! */
        const char *handle;      /* don't free! */
        const char *protocol;    /* don't free! */
        GMutex *mutex;         /* lock for the 'done' flag, free me! */
        int done;              /* is the thread done? */
        gcry_error_t result;   /* return value of otrl_privkey_generate */
};

/* some yes/no handlers */
void yes_keygen(gpointer w, void *data);
void yes_forget_fingerprint(gpointer w, void *data);
void yes_forget_context(gpointer w, void *data);

/* helper to make sure accountname and protocol match the incoming "opdata" */
struct im_connection *check_imc(void *opdata, const char *accountname,
        const char *protocol);

/* determine the nick for a given handle/protocol pair
   returns "handle/protocol" if not found */
const char *peernick(irc_t *irc, const char *handle, const char *protocol);

/* turn a hexadecimal digit into its numerical value */
int hexval(char a);

/* determine the user_t for a given handle/protocol pair
   returns NULL if not found */
user_t *peeruser(irc_t *irc, const char *handle, const char *protocol);

/* handle SMP TLVs from a received message */
void otr_handle_smp(struct im_connection *ic, const char *handle, OtrlTLV *tlvs);

/* update op/voice flag of given user according to encryption state and settings
   returns 0 if neither op_buddies nor voice_buddies is set to "encrypted",
   i.e. msgstate should be announced seperately */
int otr_update_modeflags(irc_t *irc, user_t *u);

/* show general info about the OTR subsystem; called by 'otr info' */
void show_general_otr_info(irc_t *irc);

/* show info about a given OTR context */
void show_otr_context_info(irc_t *irc, ConnContext *ctx);

/* show the list of fingerprints associated with a given context */
void show_fingerprints(irc_t *irc, ConnContext *ctx);

/* find a fingerprint by prefix (given as any number of hex strings) */
Fingerprint *match_fingerprint(irc_t *irc, ConnContext *ctx, const char **args);

/* to log out accounts during keygen */
extern void cmd_account(irc_t *irc, char **cmd);


/*** routines declared in otr.h: ***/

void otr_init(void)
{
        if(!g_thread_supported()) g_thread_init(NULL);
        OTRL_INIT;
        
        /* fill global OtrlMessageAppOps */
        global.otr_ops.policy = &op_policy;
        global.otr_ops.create_privkey = &op_create_privkey;
        global.otr_ops.is_logged_in = &op_is_logged_in;
        global.otr_ops.inject_message = &op_inject_message;
        global.otr_ops.notify = NULL;
        global.otr_ops.display_otr_message = &op_display_otr_message;
        global.otr_ops.update_context_list = NULL;
        global.otr_ops.protocol_name = NULL;
        global.otr_ops.protocol_name_free = NULL;
        global.otr_ops.new_fingerprint = &op_new_fingerprint;
        global.otr_ops.write_fingerprints = &op_write_fingerprints;
        global.otr_ops.gone_secure = &op_gone_secure;
        global.otr_ops.gone_insecure = &op_gone_insecure;
        global.otr_ops.still_secure = &op_still_secure;
        global.otr_ops.log_message = &op_log_message;
        global.otr_ops.max_message_size = &op_max_message_size;
        global.otr_ops.account_name = &op_account_name;
        global.otr_ops.account_name_free = NULL;
}

/* Notice on the otr_mutex:

   The incoming/outgoing message handlers try to lock the otr_mutex. If they succeed,
   this will prevent a concurrent keygen (possibly spawned by that very command)
   from messing up the userstate. If the lock fails, that means there already is
   a keygen in progress. Instead of blocking for an unknown time, they
   will bail out gracefully, informing the user of this temporary "coma".
   TODO: Hold back incoming/outgoing messages and process them when keygen completes?

   The other routines do not lock the otr_mutex themselves, it is done as a
   catch-all in the root command handler. Rationale:
     a) it's easy to code
     b) it makes it obvious that no command can get its userstate corrupted
     c) the "irc" struct is readily available there for feedback to the user
 */

void otr_load(irc_t *irc)
{
        char s[512];
        account_t *a;
        gcry_error_t e;

        log_message(LOGLVL_DEBUG, "otr_load '%s'", irc->nick);

        g_snprintf(s, 511, "%s%s.otr_keys", global.conf->configdir, irc->nick);
        e = otrl_privkey_read(irc->otr_us, s);
        if(e && e!=ENOENT) {
                log_message(LOGLVL_ERROR, "otr load: %s: %s", s, strerror(e));
        }
        g_snprintf(s, 511, "%s%s.otr_fprints", global.conf->configdir, irc->nick);
        e = otrl_privkey_read_fingerprints(irc->otr_us, s, NULL, NULL);
        if(e && e!=ENOENT) {
                log_message(LOGLVL_ERROR, "otr load: %s: %s", s, strerror(e));
        }
        
        /* check for otr keys on all accounts */
        for(a=irc->accounts; a; a=a->next) {
                otr_check_for_key(a);
        }
}

void otr_save(irc_t *irc)
{
        char s[512];
        gcry_error_t e;

        log_message(LOGLVL_DEBUG, "otr_save '%s'", irc->nick);

        g_snprintf(s, 511, "%s%s.otr_fprints", global.conf->configdir, irc->nick);
        e = otrl_privkey_write_fingerprints(irc->otr_us, s);
        if(e) {
                log_message(LOGLVL_ERROR, "otr save: %s: %s", s, strerror(e));
        }
}

void otr_remove(const char *nick)
{
        char s[512];
        
        log_message(LOGLVL_DEBUG, "otr_remove '%s'", nick);

        g_snprintf(s, 511, "%s%s.otr_keys", global.conf->configdir, nick);
        unlink(s);
        g_snprintf(s, 511, "%s%s.otr_fprints", global.conf->configdir, nick);
        unlink(s);
}

void otr_rename(const char *onick, const char *nnick)
{
        char s[512], t[512];
        
        log_message(LOGLVL_DEBUG, "otr_rename '%s' -> '%s'", onick, nnick);

        g_snprintf(s, 511, "%s%s.otr_keys", global.conf->configdir, onick);
        g_snprintf(t, 511, "%s%s.otr_keys", global.conf->configdir, nnick);
        rename(s,t);
        g_snprintf(s, 511, "%s%s.otr_fprints", global.conf->configdir, onick);
        g_snprintf(t, 511, "%s%s.otr_fprints", global.conf->configdir, nnick);
        rename(s,t);
}

void otr_check_for_key(account_t *a)
{
        irc_t *irc = a->irc;
        OtrlPrivKey *k;
        
        k = otrl_privkey_find(irc->otr_us, a->user, a->prpl->name);
        if(k) {
                irc_usermsg(irc, "otr: %s/%s ready",
                        a->user, a->prpl->name);
        } else {
                otr_keygen(irc, a->user, a->prpl->name);
        }
}

char *otr_handle_message(struct im_connection *ic, const char *handle, const char *msg)
{
        int ignore_msg;
        char *newmsg = NULL;
        OtrlTLV *tlvs = NULL;
        char *colormsg;
        
    if(!g_static_rec_mutex_trylock(&ic->irc->otr_mutex)) {
                irc_usermsg(ic->irc, "otr keygen in progress - msg from %s dropped",
                        peernick(ic->irc, handle, ic->acc->prpl->name));
                return NULL;
        }

        ignore_msg = otrl_message_receiving(ic->irc->otr_us, &global.otr_ops, ic,
                ic->acc->user, ic->acc->prpl->name, handle, msg, &newmsg,
                &tlvs, NULL, NULL);

        otr_handle_smp(ic, handle, tlvs);
        
        if(ignore_msg) {
                /* this was an internal OTR protocol message */
                g_static_rec_mutex_unlock(&ic->irc->otr_mutex);
                return NULL;
        } else if(!newmsg) {
                /* this was a non-OTR message */
                g_static_rec_mutex_unlock(&ic->irc->otr_mutex);
                return g_strdup(msg);
        } else {
                /* OTR has processed this message */
                ConnContext *context = otrl_context_find(ic->irc->otr_us, handle,
                        ic->acc->user, ic->acc->prpl->name, 0, NULL, NULL, NULL);
                if(context && context->msgstate == OTRL_MSGSTATE_ENCRYPTED) {
                        /* color according to f'print trust */
                        char color;
                        const char *trust = context->active_fingerprint->trust;
                        if(trust && trust[0] != '\0')
                                color='3';   /* green */
                        else
                                color='5';   /* red */
                        colormsg = g_strdup_printf("\x03%c%s\x0F", color, newmsg);
                } else {
                        colormsg = g_strdup(newmsg);
                }
                otrl_message_free(newmsg);
                g_static_rec_mutex_unlock(&ic->irc->otr_mutex);
                return colormsg;
        }
}

int otr_send_message(struct im_connection *ic, const char *handle, const char *msg, int flags)
{       
        int st;
        char *otrmsg = NULL;
        ConnContext *ctx = NULL;
        
    if(!g_static_rec_mutex_trylock(&ic->irc->otr_mutex)) {
                irc_usermsg(ic->irc, "otr keygen in progress - msg to %s not sent",
                        peernick(ic->irc, handle, ic->acc->prpl->name));
                return 1;
    }
    
        st = otrl_message_sending(ic->irc->otr_us, &global.otr_ops, ic,
                ic->acc->user, ic->acc->prpl->name, handle,
                msg, NULL, &otrmsg, NULL, NULL);
        if(st) {
                g_static_rec_mutex_unlock(&ic->irc->otr_mutex);
                return st;
        }

        ctx = otrl_context_find(ic->irc->otr_us,
                        handle, ic->acc->user, ic->acc->prpl->name,
                        1, NULL, NULL, NULL);

        if(otrmsg) {
                if(!ctx) {
                        otrl_message_free(otrmsg);
                        g_static_rec_mutex_unlock(&ic->irc->otr_mutex);
                        return 1;
                }
                st = otrl_message_fragment_and_send(&global.otr_ops, ic, ctx,
                        otrmsg, OTRL_FRAGMENT_SEND_ALL, NULL);
                otrl_message_free(otrmsg);
        } else {
                /* yeah, well, some const casts as usual... ;-) */
                st = ic->acc->prpl->buddy_msg( ic, (char *)handle, (char *)msg, flags );
        }
        
        g_static_rec_mutex_unlock(&ic->irc->otr_mutex);
        return st;
}

void cmd_otr(irc_t *irc, char **args)
{
        const command_t *cmd;
        
        if(!args[0])
                return;
        
        if(!args[1])
                return;
        
        for(cmd=otr_commands; cmd->command; cmd++) {
                if(strcmp(cmd->command, args[1]) == 0)
                        break;
        }
        
        if(!cmd->command) {
                irc_usermsg(irc, "%s: unknown subcommand \"%s\", see \x02help otr\x02",
                        args[0], args[1]);
                return;
        }
        
        if(!args[cmd->required_parameters+1]) {
                irc_usermsg(irc, "%s %s: not enough arguments (%d req.)",
                        args[0], args[1], cmd->required_parameters);
                return;
        }
        
        cmd->execute(irc, args+1);
}


/*** OTR "MessageAppOps" callbacks for global.otr_ui: ***/

OtrlPolicy op_policy(void *opdata, ConnContext *context)
{
        /* TODO: OTR policy configurable */
        return OTRL_POLICY_OPPORTUNISTIC;
}

void op_create_privkey(void *opdata, const char *accountname,
        const char *protocol)
{
        struct im_connection *ic = check_imc(opdata, accountname, protocol);
        char *s;
        
        log_message(LOGLVL_DEBUG, "op_create_privkey '%s' '%s'", accountname, protocol);

        s = g_strdup_printf("oops, no otr privkey for %s/%s - generate one now?",
                accountname, protocol);
        query_add(ic->irc, ic, s, yes_keygen, NULL, ic->acc);
}

int op_is_logged_in(void *opdata, const char *accountname,
        const char *protocol, const char *recipient)
{
        struct im_connection *ic = check_imc(opdata, accountname, protocol);
        user_t *u;

        log_message(LOGLVL_DEBUG, "op_is_logged_in '%s' '%s' '%s'", accountname, protocol, recipient);
        
        /* lookup the user_t for the given recipient */
        u = user_findhandle(ic, recipient);
        if(u) {
                if(u->online)
                        return 1;
                else
                        return 0;
        } else {
                return -1;
        }
}

void op_inject_message(void *opdata, const char *accountname,
        const char *protocol, const char *recipient, const char *message)
{
        struct im_connection *ic = check_imc(opdata, accountname, protocol);

        log_message(LOGLVL_DEBUG, "op_inject_message '%s' '%s' '%s' '%s'", accountname, protocol, recipient, message);

        if (strcmp(accountname, recipient) == 0) {
                /* huh? injecting messages to myself? */
                irc_usermsg(ic->irc, "note to self: %s", message);
        } else {
                /* need to drop some consts here :-( */
                /* TODO: get flags into op_inject_message?! */
                ic->acc->prpl->buddy_msg(ic, (char *)recipient, (char *)message, 0);
                /* ignoring return value :-/ */
        }
}

int op_display_otr_message(void *opdata, const char *accountname,
        const char *protocol, const char *username, const char *message)
{
        struct im_connection *ic = check_imc(opdata, accountname, protocol);
        char *msg = g_strdup(message);

        log_message(LOGLVL_DEBUG, "op_display_otr_message '%s' '%s' '%s' '%s'", accountname, protocol, username, message);

        strip_html(msg);
        irc_usermsg(ic->irc, "otr: %s", msg);

        g_free(msg);
        return 0;
}

void op_new_fingerprint(void *opdata, OtrlUserState us,
        const char *accountname, const char *protocol,
        const char *username, unsigned char fingerprint[20])
{
        struct im_connection *ic = check_imc(opdata, accountname, protocol);
        char hunam[45];         /* anybody looking? ;-) */
        
        otrl_privkey_hash_to_human(hunam, fingerprint);
        log_message(LOGLVL_DEBUG, "op_new_fingerprint '%s' '%s' '%s' '%s'", accountname, protocol, username, hunam);

        irc_usermsg(ic->irc, "new fingerprint for %s: %s",
                peernick(ic->irc, username, protocol), hunam);
}

void op_write_fingerprints(void *opdata)
{
        struct im_connection *ic = (struct im_connection *)opdata;

        log_message(LOGLVL_DEBUG, "op_write_fingerprints");

        otr_save(ic->irc);
}

void op_gone_secure(void *opdata, ConnContext *context)
{
        struct im_connection *ic =
                check_imc(opdata, context->accountname, context->protocol);
        user_t *u;
        const char *trust;

        log_message(LOGLVL_DEBUG, "op_gone_secure '%s' '%s' '%s'", context->accountname, context->protocol, context->username);

        u = peeruser(ic->irc, context->username, context->protocol);
        if(!u) {
                log_message(LOGLVL_ERROR,
                        "BUG: otr.c: op_gone_secure: user_t for %s/%s/%s not found!",
                        context->username, context->protocol, context->accountname);
                return;
        }
        
        trust = context->active_fingerprint->trust;
        if(trust && trust[0])
                u->encrypted = 2;
        else
                u->encrypted = 1;
        if(!otr_update_modeflags(ic->irc, u))
                irc_usermsg(ic->irc, "conversation with %s is now off the record", u->nick);
}

void op_gone_insecure(void *opdata, ConnContext *context)
{
        struct im_connection *ic =
                check_imc(opdata, context->accountname, context->protocol);
        user_t *u;

        log_message(LOGLVL_DEBUG, "op_gone_insecure '%s' '%s' '%s'", context->accountname, context->protocol, context->username);

        u = peeruser(ic->irc, context->username, context->protocol);
        if(!u) {
                log_message(LOGLVL_ERROR,
                        "BUG: otr.c: op_gone_insecure: user_t for %s/%s/%s not found!",
                        context->username, context->protocol, context->accountname);
                return;
        }
        u->encrypted = 0;
        if(!otr_update_modeflags(ic->irc, u))
                irc_usermsg(ic->irc, "conversation with %s is now in the clear", u->nick);
}

void op_still_secure(void *opdata, ConnContext *context, int is_reply)
{
        struct im_connection *ic =
                check_imc(opdata, context->accountname, context->protocol);
        user_t *u;

        log_message(LOGLVL_DEBUG, "op_still_secure '%s' '%s' '%s' is_reply=%d",
                context->accountname, context->protocol, context->username, is_reply);

        u = peeruser(ic->irc, context->username, context->protocol);
        if(!u) {
                log_message(LOGLVL_ERROR,
                        "BUG: otr.c: op_still_secure: user_t for %s/%s/%s not found!",
                        context->username, context->protocol, context->accountname);
                return;
        }
        if(context->active_fingerprint->trust[0])
                u->encrypted = 2;
        else
                u->encrypted = 1;
        if(!otr_update_modeflags(ic->irc, u))
                irc_usermsg(ic->irc, "otr connection with %s has been refreshed", u->nick);
}

void op_log_message(void *opdata, const char *message)
{
        char *msg = g_strdup(message);
        
        strip_html(msg);
        log_message(LOGLVL_INFO, "otr: %s", msg);
        g_free(msg);
}

int op_max_message_size(void *opdata, ConnContext *context)
{
        struct im_connection *ic =
                check_imc(opdata, context->accountname, context->protocol);

        return ic->acc->prpl->mms;
}

const char *op_account_name(void *opdata, const char *account, const char *protocol)
{
        struct im_connection *ic = (struct im_connection *)opdata;

        log_message(LOGLVL_DEBUG, "op_account_name '%s' '%s'", account, protocol);
        
        return peernick(ic->irc, account, protocol);
}


/*** OTR sub-command handlers ***/

void cmd_otr_disconnect(irc_t *irc, char **args)
{
        user_t *u;

        u = user_find(irc, args[1]);
        if(!u || !u->ic) {
                irc_usermsg(irc, "%s: unknown user", args[1]);
                return;
        }
        
        otrl_message_disconnect(irc->otr_us, &global.otr_ops,
                u->ic, u->ic->acc->user, u->ic->acc->prpl->name, u->handle);
        
        /* for some reason, libotr (3.1.0) doesn't do this itself: */
        if(u->encrypted) {
                ConnContext *ctx;
                ctx = otrl_context_find(irc->otr_us, u->handle, u->ic->acc->user,
                        u->ic->acc->prpl->name, 0, NULL, NULL, NULL);
                if(ctx)
                        op_gone_insecure(u->ic, ctx);
                else /* huh? */
                        u->encrypted = 0;
        }
}

void cmd_otr_connect(irc_t *irc, char **args)
{
        user_t *u;

        u = user_find(irc, args[1]);
        if(!u || !u->ic) {
                irc_usermsg(irc, "%s: unknown user", args[1]);
                return;
        }
        if(!u->online) {
                irc_usermsg(irc, "%s is offline", args[1]);
                return;
        }
        
        imc_buddy_msg(u->ic, u->handle, "?OTR?", 0);
}

void cmd_otr_smp(irc_t *irc, char **args)
{
        user_t *u;
        ConnContext *ctx;
        
        u = user_find(irc, args[1]);
        if(!u || !u->ic) {
                irc_usermsg(irc, "%s: unknown user", args[1]);
                return;
        }
        if(!u->online) {
                irc_usermsg(irc, "%s is offline", args[1]);
                return;
        }
        
        ctx = otrl_context_find(irc->otr_us, u->handle,
                u->ic->acc->user, u->ic->acc->prpl->name, 1, NULL, NULL, NULL);
        if(!ctx) {
                /* huh? out of memory or what? */
                return;
        }

        if(ctx->smstate->nextExpected != OTRL_SMP_EXPECT1) {
                log_message(LOGLVL_INFO,
                        "SMP already in phase %d, sending abort before reinitiating",
                        ctx->smstate->nextExpected+1);
                otrl_message_abort_smp(irc->otr_us, &global.otr_ops, u->ic, ctx);
                otrl_sm_state_free(ctx->smstate);
        }
        
        /* warning: the following assumes that smstates are cleared whenever an SMP
           is completed or aborted! */ 
        if(ctx->smstate->secret == NULL) {
                irc_usermsg(irc, "smp: initiating with %s...", u->nick);
                otrl_message_initiate_smp(irc->otr_us, &global.otr_ops,
                        u->ic, ctx, (unsigned char *)args[2], strlen(args[2]));
                /* smp is now in EXPECT2 */
        } else {
                /* if we're still in EXPECT1 but smstate is initialized, we must have
                   received the SMP1, so let's issue a response */
                irc_usermsg(irc, "smp: responding to %s...", u->nick);
                otrl_message_respond_smp(irc->otr_us, &global.otr_ops,
                        u->ic, ctx, (unsigned char *)args[2], strlen(args[2]));
                /* smp is now in EXPECT3 */
        }
}

void cmd_otr_trust(irc_t *irc, char **args)
{
        user_t *u;
        ConnContext *ctx;
        unsigned char raw[20];
        Fingerprint *fp;
        int i,j;
        
        u = user_find(irc, args[1]);
        if(!u || !u->ic) {
                irc_usermsg(irc, "%s: unknown user", args[1]);
                return;
        }
        
        ctx = otrl_context_find(irc->otr_us, u->handle,
                u->ic->acc->user, u->ic->acc->prpl->name, 0, NULL, NULL, NULL);
        if(!ctx) {
                irc_usermsg(irc, "%s: no otr context with user", args[1]);
                return;
        }
        
        /* convert given fingerprint to raw representation */
        for(i=0; i<5; i++) {
                for(j=0; j<4; j++) {
                        char *p = args[2+i]+(2*j);
                        char *q = p+1;
                        int x, y;
                        
                        if(!*p || !*q) {
                                irc_usermsg(irc, "failed: truncated fingerprint block %d", i+1);
                                return;
                        }
                        
                        x = hexval(*p);
                        y = hexval(*q);
                        if(x<0) {
                                irc_usermsg(irc, "failed: %d. hex digit of block %d out of range", 2*j+1, i+1);
                                return;
                        }
                        if(y<0) {
                                irc_usermsg(irc, "failed: %d. hex digit of block %d out of range", 2*j+2, i+1);
                                return;
                        }

                        raw[i*4+j] = x*16 + y;
                }
        }
        fp = otrl_context_find_fingerprint(ctx, raw, 0, NULL);
        if(!fp) {
                irc_usermsg(irc, "failed: no such fingerprint for %s", args[1]);
        } else {
                char *trust = args[7] ? args[7] : "affirmed";
                otrl_context_set_trust(fp, trust);
                irc_usermsg(irc, "fingerprint match, trust set to \"%s\"", trust);
                if(u->encrypted)
                        u->encrypted = 2;
                otr_update_modeflags(irc, u);
        }
}

void cmd_otr_info(irc_t *irc, char **args)
{
        if(!args[1]) {
                show_general_otr_info(irc);
        } else {
                char *arg = g_strdup(args[1]);
                char *myhandle, *handle, *protocol;
                ConnContext *ctx;
                
                /* interpret arg as 'user/protocol/account' if possible */
                protocol = strchr(arg, '/');
                if(protocol) {
                        *(protocol++) = '\0';
                        myhandle = strchr(protocol, '/');
                }
                if(protocol && myhandle) {
                        *(myhandle++) = '\0';
                        handle = arg;
                        ctx = otrl_context_find(irc->otr_us, handle, myhandle, protocol, 0, NULL, NULL, NULL);
                        if(!ctx) {
                                irc_usermsg(irc, "no such context");
                                g_free(arg);
                                return;
                        }
                } else {
                        user_t *u = user_find(irc, args[1]);
                        if(!u || !u->ic) {
                                irc_usermsg(irc, "%s: unknown user", args[1]);
                                g_free(arg);
                                return;
                        }
                        ctx = otrl_context_find(irc->otr_us, u->handle, u->ic->acc->user,
                                u->ic->acc->prpl->name, 0, NULL, NULL, NULL);
                        if(!ctx) {
                                irc_usermsg(irc, "no otr context with %s", args[1]);
                                g_free(arg);
                                return;
                        }
                }
        
                /* show how we resolved the (nick) argument, if we did */
                if(handle!=arg) {
                        irc_usermsg(irc, "%s is %s/%s; we are %s/%s to them", args[1],
                                ctx->username, ctx->protocol, ctx->accountname, ctx->protocol);
                }
                show_otr_context_info(irc, ctx);
                g_free(arg);
        }
}

void cmd_otr_keygen(irc_t *irc, char **args)
{
        int i, n;
        account_t *a;
        
        n = atoi(args[1]);
        if(n<0 || (!n && strcmp(args[1], "0"))) {
                irc_usermsg(irc, "%s: invalid account number", args[1]);
                return;
        }
        
        a = irc->accounts;
        for(i=0; i<n && a; i++, a=a->next);
        if(!a) {
                irc_usermsg(irc, "%s: no such account", args[1]);
                return;
        }
        
        if(otrl_privkey_find(irc->otr_us, a->user, a->prpl->name)) {
                char *s = g_strdup_printf("account %d already has a key, replace it?", n);
                query_add(irc, a->ic, s, yes_keygen, NULL, a);
        } else {
                otr_keygen(irc, a->user, a->prpl->name);
        }
}

void yes_forget_fingerprint(gpointer w, void *data)
{
        struct im_connection *ic = (struct im_connection *)w;
        Fingerprint *fp = (Fingerprint *)data;
        
        if(fp == fp->context->active_fingerprint) {
                irc_usermsg(ic->irc, "that fingerprint is active, terminate otr connection first");
                return;
        }
                
        otrl_context_forget_fingerprint(fp, 0);
}

void yes_forget_context(gpointer w, void *data)
{
        struct im_connection *ic = (struct im_connection *)w;
        ConnContext *ctx = (ConnContext *)data;
        
        if(ctx->msgstate == OTRL_MSGSTATE_ENCRYPTED) {
                irc_usermsg(ic->irc, "active otr connection with %s, terminate it first",
                        peernick(ic->irc, ctx->username, ctx->protocol));
                return;
        }
                
        if(ctx->msgstate == OTRL_MSGSTATE_FINISHED)
                otrl_context_force_plaintext(ctx);
        otrl_context_forget(ctx);
}

void cmd_otr_forget(irc_t *irc, char **args)
{
        if(!strcmp(args[1], "fingerprint"))
        {
                user_t *u;
                ConnContext *ctx;
                Fingerprint *fp;
                char human[54];
                char *s;
                
                if(!args[3]) {
                        irc_usermsg(irc, "otr %s %s: not enough arguments (2 req.)", args[0], args[1]);
                        return;
                }
                
                u = user_find(irc, args[2]);
                if(!u || !u->ic) {
                        irc_usermsg(irc, "%s: unknown user", args[2]);
                        return;
                }
                
                ctx = otrl_context_find(irc->otr_us, u->handle, u->ic->acc->user,
                        u->ic->acc->prpl->name, 0, NULL, NULL, NULL);
                if(!ctx) {
                        irc_usermsg(irc, "no otr context with %s", args[2]);
                        return;
                }
                
                fp = match_fingerprint(irc, ctx, ((const char **)args)+3);
                if(!fp) {
                        /* match_fingerprint does error messages */
                        return;
                }
                
                if(fp == ctx->active_fingerprint) {
                        irc_usermsg(irc, "that fingerprint is active, terminate otr connection first");
                        return;
                }
                
                otrl_privkey_hash_to_human(human, fp->fingerprint);
                s = g_strdup_printf("about to forget fingerprint %s, are you sure?", human);
                query_add(irc, u->ic, s, yes_forget_fingerprint, NULL, fp);
        }
        
        else if(!strcmp(args[1], "context"))
        {
                user_t *u;
                ConnContext *ctx;
                char *s;
                
                u = user_find(irc, args[2]);
                if(!u || !u->ic) {
                        irc_usermsg(irc, "%s: unknown user", args[2]);
                        return;
                }
                
                ctx = otrl_context_find(irc->otr_us, u->handle, u->ic->acc->user,
                        u->ic->acc->prpl->name, 0, NULL, NULL, NULL);
                if(!ctx) {
                        irc_usermsg(irc, "no otr context with %s", args[2]);
                        return;
                }
                
                if(ctx->msgstate == OTRL_MSGSTATE_ENCRYPTED) {
                        irc_usermsg(irc, "active otr connection with %s, terminate it first", args[2]);
                        return;
                }
                
                s = g_strdup_printf("about to forget otr data about %s, are you sure?", args[2]);
                query_add(irc, u->ic, s, yes_forget_context, NULL, ctx);
        }
        
        else if(!strcmp(args[1], "key"))
        {
                irc_usermsg(irc, "n/a: TODO");
        }
        
        else
        {
                irc_usermsg(irc, "otr %s: unknown subcommand \"%s\", see \x02help otr forget\x02",
                        args[0], args[1]);
        }
}


/*** local helpers / subroutines: ***/

/* Socialist Millionaires' Protocol */
void otr_handle_smp(struct im_connection *ic, const char *handle, OtrlTLV *tlvs)
{
        irc_t *irc = ic->irc;
        OtrlUserState us = irc->otr_us;
        OtrlMessageAppOps *ops = &global.otr_ops;
        OtrlTLV *tlv = NULL;
        ConnContext *context;
        NextExpectedSMP nextMsg;
        user_t *u;

        u = user_findhandle(ic, handle);
        if(!u) return;
        context = otrl_context_find(us, handle,
                ic->acc->user, ic->acc->prpl->name, 1, NULL, NULL, NULL);
        if(!context) {
                /* huh? out of memory or what? */
                return;
        }
        nextMsg = context->smstate->nextExpected;

        tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP1);
        if (tlv) {
                if (nextMsg != OTRL_SMP_EXPECT1) {
                        irc_usermsg(irc, "smp %s: spurious SMP1 received, aborting", u->nick);
                        otrl_message_abort_smp(us, ops, u->ic, context);
                        otrl_sm_state_free(context->smstate);
                } else {
                        irc_usermsg(irc, "smp: initiated by %s"
                                " - respond with \x02otr smp %s <secret>\x02",
                                u->nick, u->nick);
                        /* smp stays in EXPECT1 until user responds */
                }
        }
        tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP2);
        if (tlv) {
                if (nextMsg != OTRL_SMP_EXPECT2) {
                        irc_usermsg(irc, "smp %s: spurious SMP2 received, aborting", u->nick);
                        otrl_message_abort_smp(us, ops, u->ic, context);
                        otrl_sm_state_free(context->smstate);
                } else {
                        /* SMP2 received, otrl_message_receiving will have sent SMP3 */
                        context->smstate->nextExpected = OTRL_SMP_EXPECT4;
                }
        }
        tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP3);
        if (tlv) {
                if (nextMsg != OTRL_SMP_EXPECT3) {
                        irc_usermsg(irc, "smp %s: spurious SMP3 received, aborting", u->nick);
                        otrl_message_abort_smp(us, ops, u->ic, context);
                        otrl_sm_state_free(context->smstate);
                } else {
                        /* SMP3 received, otrl_message_receiving will have sent SMP4 and set fp trust */
                        const char *trust = context->active_fingerprint->trust;
                        if(!trust || trust[0]=='\0') {
                                irc_usermsg(irc, "smp %s: secrets did not match, fingerprint not trusted",
                                        u->nick);
                        } else {
                                irc_usermsg(irc, "smp %s: secrets proved equal, fingerprint trusted",
                                        u->nick);
                        }
                        otrl_sm_state_free(context->smstate);
                        /* smp is in back in EXPECT1 */
                }
        }
        tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP4);
        if (tlv) {
                if (nextMsg != OTRL_SMP_EXPECT4) {
                        irc_usermsg(irc, "smp %s: spurious SMP4 received, aborting", u->nick);
                        otrl_message_abort_smp(us, ops, u->ic, context);
                        otrl_sm_state_free(context->smstate);
                } else {
                        /* SMP4 received, otrl_message_receiving will have set fp trust */
                        const char *trust = context->active_fingerprint->trust;
                        if(!trust || trust[0]=='\0') {
                                irc_usermsg(irc, "smp %s: secrets did not match, fingerprint not trusted",
                                        u->nick);
                        } else {
                                irc_usermsg(irc, "smp %s: secrets proved equal, fingerprint trusted",
                                        u->nick);
                        }
                        otrl_sm_state_free(context->smstate);
                        /* smp is in back in EXPECT1 */
                }
        }
        tlv = otrl_tlv_find(tlvs, OTRL_TLV_SMP_ABORT);
        if (tlv) {
                irc_usermsg(irc, "smp: received abort from %s", u->nick);
                otrl_sm_state_free(context->smstate);
                /* smp is in back in EXPECT1 */
        }
}

/* helper to assert that account and protocol names given to ops below always
   match the im_connection passed through as opdata */
struct im_connection *check_imc(void *opdata, const char *accountname,
        const char *protocol)
{
        struct im_connection *ic = (struct im_connection *)opdata;

        if (strcmp(accountname, ic->acc->user) != 0) {
                log_message(LOGLVL_WARNING,
                        "otr: internal account name mismatch: '%s' vs '%s'",
                        accountname, ic->acc->user);
        }
        if (strcmp(protocol, ic->acc->prpl->name) != 0) {
                log_message(LOGLVL_WARNING,
                        "otr: internal protocol name mismatch: '%s' vs '%s'",
                        protocol, ic->acc->prpl->name);
        }
        
        return ic;
}

user_t *peeruser(irc_t *irc, const char *handle, const char *protocol)
{
        user_t *u;
        
        log_message(LOGLVL_DEBUG, "peeruser '%s' '%s'", handle, protocol);
        
        for(u=irc->users; u; u=u->next) {
                struct prpl *prpl;
                if(!u->ic || !u->handle)
                        continue;
                prpl = u->ic->acc->prpl;
                if(strcmp(prpl->name, protocol) == 0
                        && prpl->handle_cmp(u->handle, handle) == 0) {
                        return u;
                }
        }
        
        return NULL;
}

int hexval(char a)
{
        int x=tolower(a);
        
        if(x>='a' && x<='f')
                x = x - 'a' + 10;
        else if(x>='0' && x<='9')
                x = x - '0';
        else
                return -1;
        
        return x;
}

const char *peernick(irc_t *irc, const char *handle, const char *protocol)
{
        static char fallback[512];
        
        user_t *u = peeruser(irc, handle, protocol);
        if(u) {
                return u->nick;
        } else {
                g_snprintf(fallback, 511, "%s/%s", handle, protocol);
                return fallback;
        }
}

int otr_update_modeflags(irc_t *irc, user_t *u)
{
        char *vb = set_getstr(&irc->set, "voice_buddies");
        char *hb = set_getstr(&irc->set, "halfop_buddies");
        char *ob = set_getstr(&irc->set, "op_buddies");
        int encrypted = u->encrypted;
        int trusted = u->encrypted > 1;
        char flags[7];
        int nflags=0;
        char *p = flags;
        char *from;
        int i;
        
        if(!strcmp(vb, "encrypted")) {
                *(p++) = encrypted ? '+' : '-';
                *(p++) = 'v';
                nflags++;
        } else if(!strcmp(vb, "trusted")) {
                *(p++) = trusted ? '+' : '-';
                *(p++) = 'v';
                nflags++;
        }
        if(!strcmp(hb, "encrypted")) {
                *(p++) = encrypted ? '+' : '-';
                *(p++) = 'h';
                nflags++;
        } else if(!strcmp(hb, "trusted")) {
                *(p++) = trusted ? '+' : '-';
                *(p++) = 'h';
                nflags++;
        }
        if(!strcmp(ob, "encrypted")) {
                *(p++) = encrypted ? '+' : '-';
                *(p++) = 'o';
                nflags++;
        } else if(!strcmp(ob, "trusted")) {
                *(p++) = trusted ? '+' : '-';
                *(p++) = 'o';
                nflags++;
        }
        *p = '\0';
        
        p = g_malloc(nflags * (strlen(u->nick)+1) + 1);
        *p = '\0';
        if(!p)
                return 0;
        for(i=0; i<nflags; i++) {
                strcat(p, " ");
                strcat(p, u->nick);
        }
        if(set_getbool(&irc->set, "simulate_netsplit"))
                from = g_strdup(irc->myhost);
        else
                from = g_strdup_printf("%s!%s@%s", irc->mynick, irc->mynick, irc->myhost);
        irc_write(irc, ":%s MODE %s %s%s", from, irc->channel, flags, p);
        g_free(from);
        g_free(p);
                
        return 1;
}

void show_fingerprints(irc_t *irc, ConnContext *ctx)
{
        char human[45];
        Fingerprint *fp;
        const char *trust;
        int count=0;
        
        for(fp=&ctx->fingerprint_root; fp; fp=fp->next) {
                if(!fp->fingerprint)
                        continue;
                count++;
                otrl_privkey_hash_to_human(human, fp->fingerprint);
                if(!fp->trust || fp->trust[0] == '\0') {
                        trust="untrusted";
                } else {
                        trust=fp->trust;
                }
                if(fp == ctx->active_fingerprint) {
                        irc_usermsg(irc, "  \x02%s (%s)\x02", human, trust);
                } else {
                        irc_usermsg(irc, "  %s (%s)", human, trust);
                }
        }
        if(count==0)
                irc_usermsg(irc, "  no fingerprints");
}

Fingerprint *match_fingerprint(irc_t *irc, ConnContext *ctx, const char **args)
{
        Fingerprint *fp, *fp2;
        char human[45];
        char prefix[45], *p;
        int n;
        int i,j;
        
        /* assemble the args into a prefix in standard "human" form */
        n=0;
        p=prefix;
        for(i=0; args[i]; i++) {
                for(j=0; args[i][j]; j++) {
                        char c = toupper(args[i][j]);
                        
                        if(n>=40) {
                                irc_usermsg(irc, "too many fingerprint digits given, expected at most 40");
                                return NULL;
                        }
                        
                        if( (c>='A' && c<='F') || (c>='0' && c<='9') ) {
                                *(p++) = c;
                        } else {
                                irc_usermsg(irc, "invalid hex digit '%c' in block %d", args[i][j], i+1);
                                return NULL;
                        }
                        
                        n++;
                        if(n%8 == 0)
                                *(p++) = ' ';
                }
        }
        *p = '\0';
        log_message(LOGLVL_DEBUG, "match_fingerprint '%s'", prefix);
        log_message(LOGLVL_DEBUG, "n=%d strlen(prefix)=%d", n, strlen(prefix));
        
        /* find first fingerprint with the given prefix */
        n = strlen(prefix);
        for(fp=&ctx->fingerprint_root; fp; fp=fp->next) {
                if(!fp->fingerprint)
                        continue;
                otrl_privkey_hash_to_human(human, fp->fingerprint);
                if(!strncmp(prefix, human, n))
                        break;
        }
        if(!fp) {
                irc_usermsg(irc, "%s: no match", prefix);
                return NULL;
        }
        
        /* make sure the match, if any, is unique */
        for(fp2=fp->next; fp2; fp2=fp2->next) {
                if(!fp2->fingerprint)
                        continue;
                otrl_privkey_hash_to_human(human, fp2->fingerprint);
                if(!strncmp(prefix, human, n))
                        break;
        }
        if(fp2) {
                irc_usermsg(irc, "%s: multiple matches", prefix);
                return NULL;
        }
        
        return fp;
}

void show_general_otr_info(irc_t *irc)
{
        ConnContext *ctx;
        OtrlPrivKey *key;
        char human[45];

        /* list all privkeys */
        irc_usermsg(irc, "\x1fprivate keys:\x1f");
        for(key=irc->otr_us->privkey_root; key; key=key->next) {
                const char *hash;
                
                switch(key->pubkey_type) {
                case OTRL_PUBKEY_TYPE_DSA:
                        irc_usermsg(irc, "  %s/%s - DSA", key->accountname, key->protocol);
                        break;
                default:
                        irc_usermsg(irc, "  %s/%s - type %d", key->accountname, key->protocol,
                                key->pubkey_type);
                }

                /* No, it doesn't make much sense to search for the privkey again by
                   account/protocol, but libotr currently doesn't provide a direct routine
                   for hashing a given 'OtrlPrivKey'... */
                hash = otrl_privkey_fingerprint(irc->otr_us, human, key->accountname, key->protocol);
                if(hash) /* should always succeed */
                        irc_usermsg(irc, "    %s", human);
        }

        /* list all contexts */
        irc_usermsg(irc, "%s", "");
        irc_usermsg(irc, "\x1f" "connection contexts:\x1f (bold=currently encrypted)");
        for(ctx=irc->otr_us->context_root; ctx; ctx=ctx->next) {\
                user_t *u;
                char *userstring;
                
                u = peeruser(irc, ctx->username, ctx->protocol);
                if(u)
                        userstring = g_strdup_printf("%s/%s/%s (%s)",
                                ctx->username, ctx->protocol, ctx->accountname, u->nick);
                else
                        userstring = g_strdup_printf("%s/%s/%s",
                                ctx->username, ctx->protocol, ctx->accountname);
                
                if(ctx->msgstate == OTRL_MSGSTATE_ENCRYPTED) {
                        irc_usermsg(irc, "  \x02%s\x02", userstring);
                } else {
                        irc_usermsg(irc, "  %s", userstring);
                }
                
                g_free(userstring);
        }
}

void show_otr_context_info(irc_t *irc, ConnContext *ctx)
{
        switch(ctx->otr_offer) {
        case OFFER_NOT:
                irc_usermsg(irc, "  otr offer status: none sent");
                break;
        case OFFER_SENT:
                irc_usermsg(irc, "  otr offer status: awaiting reply");
                break;
        case OFFER_ACCEPTED:
                irc_usermsg(irc, "  otr offer status: accepted our offer");
                break;
        case OFFER_REJECTED:
                irc_usermsg(irc, "  otr offer status: ignored our offer");
                break;
        default:
                irc_usermsg(irc, "  otr offer status: %d", ctx->otr_offer);
        }

        switch(ctx->msgstate) {
        case OTRL_MSGSTATE_PLAINTEXT:
                irc_usermsg(irc, "  connection state: cleartext");
                break;
        case OTRL_MSGSTATE_ENCRYPTED:
                irc_usermsg(irc, "  connection state: encrypted (v%d)", ctx->protocol_version);
                break;
        case OTRL_MSGSTATE_FINISHED:
                irc_usermsg(irc, "  connection state: shut down");
                break;
        default:
                irc_usermsg(irc, "  connection state: %d", ctx->msgstate);
        }

    irc_usermsg(irc, "  fingerprints: (bold=active)");  
        show_fingerprints(irc, ctx);
}

void otr_keygen(irc_t *irc, const char *handle, const char *protocol)
{
        char *account_off[] = {"account", "off", NULL};
        GError *err;
        GThread *thr;
        struct kgdata *kg;
        gint ev;
        
        kg = g_new0(struct kgdata, 1);
        if(!kg) {
                irc_usermsg(irc, "otr keygen failed: out of memory");
                return;
        }

        /* Assemble the job description to be passed to thread and handler */
        kg->irc = irc;
        kg->keyfile = g_strdup_printf("%s%s.otr_keys", global.conf->configdir, kg->irc->nick);
        if(!kg->keyfile) {
                irc_usermsg(irc, "otr keygen failed: out of memory");
                g_free(kg);
                return;
        }
        kg->handle = handle;
        kg->protocol = protocol;
        kg->mutex = g_mutex_new();
        if(!kg->mutex) {
                irc_usermsg(irc, "otr keygen failed: couldn't create mutex");
                g_free(kg->keyfile);
                g_free(kg);
                return;
        }
        kg->done = 0;

        /* Poll for completion of the thread periodically. I would have preferred
           to just wait on a pipe but this way it's portable to Windows. *sigh*
        */
        ev = b_timeout_add(1000, &keygen_finish_handler, kg);
        if(!ev) {
                irc_usermsg(irc, "otr keygen failed: couldn't register timeout");
                g_free(kg->keyfile);
                g_mutex_free(kg->mutex);
                g_free(kg);
                return;
        }

        /* tell the user what's happening, go comatose, and start the keygen */
        irc_usermsg(irc, "going comatose for otr key generation, this will take a moment");
        irc_usermsg(irc, "all accounts logging out, user commands disabled");
        cmd_account(irc, account_off);
        irc_usermsg(irc, "generating new otr privkey for %s/%s...",
                handle, protocol);
        
        thr = g_thread_create(&otr_keygen_thread_func, kg, FALSE, &err);
        if(!thr) {
                irc_usermsg(irc, "otr keygen failed: %s", err->message);
                g_free(kg->keyfile);
                g_mutex_free(kg->mutex);
                g_free(kg);
                b_event_remove(ev);
        }
}

gpointer otr_keygen_thread_func(gpointer data)
{
        struct kgdata *kg = (struct kgdata *)data;
        
        /* lock OTR subsystem and do the work */
        g_static_rec_mutex_lock(&kg->irc->otr_mutex);
        kg->result = otrl_privkey_generate(kg->irc->otr_us, kg->keyfile, kg->handle,
                kg->protocol);
        g_static_rec_mutex_unlock(&kg->irc->otr_mutex);
        /* OTR enabled again */
        
        /* notify mainloop */
        g_mutex_lock(kg->mutex);
        kg->done = 1;
        g_mutex_unlock(kg->mutex);
        
        return NULL;
}

gboolean keygen_finish_handler(gpointer data, gint fd, b_input_condition cond)
{
        struct kgdata *kg = (struct kgdata *)data;
        int done;
        
        g_mutex_lock(kg->mutex);
        done = kg->done;
        g_mutex_unlock(kg->mutex);
        if(kg->done) {
                if(kg->result) {
                        irc_usermsg(kg->irc, "otr keygen: %s", strerror(kg->result));
                } else {
                        irc_usermsg(kg->irc, "otr keygen for %s/%s complete", kg->handle, kg->protocol);
                }
                g_free(kg->keyfile);
                g_mutex_free(kg->mutex);
                g_free(kg);
                return FALSE; /* unregister timeout */
        }

        return TRUE;  /* still working, continue checking */
}

void yes_keygen(gpointer w, void *data)
{
        account_t *acc = (account_t *)data;
        
        otr_keygen(acc->irc, acc->user, acc->prpl->name);
}


#else /* WITH_OTR undefined */

void cmd_otr(irc_t *irc, char **args)
{
        irc_usermsg(irc, "otr: n/a, compiled without OTR support");
}

#endif