/* modules/m_sasl.c
 *   Copyright (C) 2006 Michael Tharp <gxti@partiallystapled.com>
 *   Copyright (C) 2006 charybdis development team
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * 1.Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * 2.Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 3.The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include "stdinc.h"

#include "client.h"
#include "hash.h"
#include "send.h"
#include "msg.h"
#include "modules.h"
#include "numeric.h"
#include "s_serv.h"
#include "s_stats.h"
#include "string.h"

static int mr_authenticate(struct Client *, struct Client *, int, const char **);
static int me_sasl(struct Client *, struct Client *, int, const char **);
static int server_auth_sasl(struct Client *);

static void abort_sasl(struct Client *);
static void abort_sasl_exit(hook_data_client_exit *);

struct Message authenticate_msgtab = {
    "AUTHENTICATE", 0, 0, 0, MFLG_SLOW,
    {{mr_authenticate, 2}, mg_reg, mg_ignore, mg_ignore, mg_ignore, mg_reg}
};
struct Message sasl_msgtab = {
    "SASL", 0, 0, 0, MFLG_SLOW,
    {mg_ignore, mg_ignore, mg_ignore, mg_ignore, {me_sasl, 5}, mg_ignore}
};

mapi_clist_av1 sasl_clist[] = {
    &authenticate_msgtab, &sasl_msgtab, NULL
};
mapi_hfn_list_av1 sasl_hfnlist[] = {
    { "new_local_user",	(hookfn) abort_sasl },
    { "client_exit",	(hookfn) abort_sasl_exit },
    { NULL, NULL }
};

DECLARE_MODULE_AV1(sasl, NULL, NULL, sasl_clist, NULL, sasl_hfnlist, "$Revision: 1409 $");

static int
mr_authenticate(struct Client *client_p, struct Client *source_p,
                int parc, const char *parv[])
{
    struct Client *agent_p = NULL;

    /* They really should use CAP for their own sake. */
    if(!IsCapable(source_p, CLICAP_SASL))
        return 0;

    if (strlen(client_p->id) == 3) {
        exit_client(client_p, client_p, client_p, "Mixing client and server protocol");
        return 0;
    }

    if(source_p->preClient->sasl_complete) {
        sendto_one(source_p, form_str(ERR_SASLALREADY), me.name, EmptyString(source_p->name) ? "*" : source_p->name);
        return 0;
    }

    if(strlen(parv[1]) > 400) {
        sendto_one(source_p, form_str(ERR_SASLTOOLONG), me.name, EmptyString(source_p->name) ? "*" : source_p->name);
        return 0;
    }

    if(!*source_p->id) {
        /* Allocate a UID. */
        strcpy(source_p->id, generate_uid());
        add_to_id_hash(source_p->id, source_p);
    }

    if(*source_p->preClient->sasl_agent)
        agent_p = find_id(source_p->preClient->sasl_agent);

    if(agent_p == NULL) {
        if (!strcmp(parv[1], "EXTERNAL") && source_p->certfp != NULL)
            sendto_server(NULL, NULL, CAP_TS6|CAP_ENCAP, NOCAPS, ":%s ENCAP * SASL %s * S %s %s", me.id,
                          source_p->id, parv[1],
                          source_p->certfp);
        else
            sendto_server(NULL, NULL, CAP_TS6|CAP_ENCAP, NOCAPS, ":%s ENCAP * SASL %s * S %s", me.id,
                          source_p->id, parv[1]);
    } else
        sendto_one(agent_p, ":%s ENCAP %s SASL %s %s C %s", me.id, agent_p->servptr->name,
                   source_p->id, agent_p->id, parv[1]);
    source_p->preClient->sasl_out++;

    return 0;
}

static int
me_sasl(struct Client *client_p, struct Client *source_p,
        int parc, const char *parv[])
{
    struct Client *target_p, *agent_p;

    /* Let propagate if not addressed to us, or if broadcast.
     * Only SASL agents can answer global requests.
     */
    if(strncmp(parv[2], me.id, 3))
        return 0;

    if((target_p = find_id(parv[2])) == NULL)
        return 0;

    if(target_p->preClient == NULL)
        return 0;

    if((agent_p = find_id(parv[1])) == NULL)
        return 0;

    if(source_p != agent_p->servptr) /* WTF?! */
        return 0;

    /* We only accept messages from SASL agents; these must have umode +S
     * (so the server must be listed in a service{} block).
     */
    if(!IsService(agent_p))
        return 0;

    /* Reject if someone has already answered. */
    if(*target_p->preClient->sasl_agent && strncmp(parv[1], target_p->preClient->sasl_agent, IDLEN))
        return 0;
    else if(!*target_p->preClient->sasl_agent)
        rb_strlcpy(target_p->preClient->sasl_agent, parv[1], IDLEN);

    if(*parv[3] == 'C')
        sendto_one(target_p, "AUTHENTICATE %s", parv[4]);
    else if(*parv[3] == 'D') {
        if(*parv[4] == 'F')
            sendto_one(target_p, form_str(ERR_SASLFAIL), me.name, EmptyString(target_p->name) ? "*" : target_p->name);
        else if(*parv[4] == 'S') {
            sendto_one(target_p, form_str(RPL_SASLSUCCESS), me.name, EmptyString(target_p->name) ? "*" : target_p->name);
            target_p->preClient->sasl_complete = 1;
            ServerStats.is_ssuc++;
            server_auth_sasl(target_p);
        }
        *target_p->preClient->sasl_agent = '\0'; /* Blank the stored agent so someone else can answer */
    }

    return 0;
}

static int server_auth_sasl(struct Client *client_p)
{
    if (client_p->localClient->auth_user != NULL) {
        memset(client_p->localClient->auth_user, 0,
               strlen(client_p->localClient->auth_user));
        rb_free(client_p->localClient->auth_user);
        client_p->localClient->auth_user = NULL;
    }

    if (client_p->user != NULL && client_p->user->suser != NULL)
        client_p->localClient->auth_user = rb_strndup(client_p->user->suser, PASSWDLEN);

    return 0;
}

/* If the client never finished authenticating but is
 * registering anyway, abort the exchange.
 */
static void
abort_sasl(struct Client *data)
{
    if(data->preClient->sasl_out == 0 || data->preClient->sasl_complete)
        return;

    data->preClient->sasl_out = data->preClient->sasl_complete = 0;
    ServerStats.is_sbad++;

    if(!IsClosing(data))
        sendto_one(data, form_str(ERR_SASLABORTED), me.name, EmptyString(data->name) ? "*" : data->name);

    if(*data->preClient->sasl_agent) {
        struct Client *agent_p = find_id(data->preClient->sasl_agent);
        if(agent_p) {
            sendto_one(agent_p, ":%s ENCAP %s SASL %s %s D A", me.id, agent_p->servptr->name,
                       data->id, agent_p->id);
            return;
        }
    }

    sendto_server(NULL, NULL, CAP_TS6|CAP_ENCAP, NOCAPS, ":%s ENCAP * SASL %s * D A", me.id,
                  data->id);
}

static void
abort_sasl_exit(hook_data_client_exit *data)
{
    if (data->target->preClient)
        abort_sasl(data->target);
}

