source: protocols/oscar/rxhandlers.c @ 8fdeaa5

/*
 * aim_rxhandlers.c
 *
 * This file contains most all of the incoming packet handlers, along
 * with aim_rxdispatch(), the Rx dispatcher.  Queue/list management is
 * actually done in aim_rxqueue.c.
 *
 */

#include <aim.h>

struct aim_rxcblist_s {
        guint16 family;
        guint16 type;
        aim_rxcallback_t handler;
        u_short flags;
        struct aim_rxcblist_s *next;
};

aim_module_t *aim__findmodulebygroup(aim_session_t *sess, guint16 group)
{
        aim_module_t *cur;

        for (cur = (aim_module_t *) sess->modlistv; cur; cur = cur->next) {
                if (cur->family == group) {
                        return cur;
                }
        }

        return NULL;
}

static aim_module_t *aim__findmodule(aim_session_t *sess, const char *name)
{
        aim_module_t *cur;

        for (cur = (aim_module_t *) sess->modlistv; cur; cur = cur->next) {
                if (strcmp(name, cur->name) == 0) {
                        return cur;
                }
        }

        return NULL;
}

int aim__registermodule(aim_session_t *sess, int (*modfirst)(aim_session_t *, aim_module_t *))
{
        aim_module_t *mod;

        if (!sess || !modfirst) {
                return -1;
        }

        if (!(mod = g_new0(aim_module_t, 1))) {
                return -1;
        }

        if (modfirst(sess, mod) == -1) {
                g_free(mod);
                return -1;
        }

        if (aim__findmodule(sess, mod->name)) {
                if (mod->shutdown) {
                        mod->shutdown(sess, mod);
                }
                g_free(mod);
                return -1;
        }

        mod->next = (aim_module_t *) sess->modlistv;
        sess->modlistv = mod;


        return 0;
}

void aim__shutdownmodules(aim_session_t *sess)
{
        aim_module_t *cur;

        for (cur = (aim_module_t *) sess->modlistv; cur; ) {
                aim_module_t *tmp;

                tmp = cur->next;

                if (cur->shutdown) {
                        cur->shutdown(sess, cur);
                }

                g_free(cur);

                cur = tmp;
        }

        sess->modlistv = NULL;

        return;
}

static int consumesnac(aim_session_t *sess, aim_frame_t *rx)
{
        aim_module_t *cur;
        aim_modsnac_t snac;

        if (aim_bstream_empty(&rx->data) < 10) {
                return 0;
        }

        snac.family = aimbs_get16(&rx->data);
        snac.subtype = aimbs_get16(&rx->data);
        snac.flags = aimbs_get16(&rx->data);
        snac.id = aimbs_get32(&rx->data);

        /* Contains TLV(s) in the FNAC header */
        if (snac.flags & 0x8000) {
                aim_bstream_advance(&rx->data, aimbs_get16(&rx->data));
        } else if (snac.flags & 0x0001) {
                /* Following SNAC will be related */
        }

        for (cur = (aim_module_t *) sess->modlistv; cur; cur = cur->next) {

                if (!(cur->flags & AIM_MODFLAG_MULTIFAMILY) &&
                    (cur->family != snac.family)) {
                        continue;
                }

                if (cur->snachandler(sess, cur, rx, &snac, &rx->data)) {
                        return 1;
                }

        }

        return 0;
}

static int consumenonsnac(aim_session_t *sess, aim_frame_t *rx, guint16 family, guint16 subtype)
{
        aim_module_t *cur;
        aim_modsnac_t snac;

        snac.family = family;
        snac.subtype = subtype;
        snac.flags = snac.id = 0;

        for (cur = (aim_module_t *) sess->modlistv; cur; cur = cur->next) {

                if (!(cur->flags & AIM_MODFLAG_MULTIFAMILY) &&
                    (cur->family != snac.family)) {
                        continue;
                }

                if (cur->snachandler(sess, cur, rx, &snac, &rx->data)) {
                        return 1;
                }

        }

        return 0;
}

static int negchan_middle(aim_session_t *sess, aim_frame_t *fr)
{
        aim_tlvlist_t *tlvlist;
        char *msg = NULL;
        guint16 code = 0;
        aim_rxcallback_t userfunc;
        int ret = 1;

        if (aim_bstream_empty(&fr->data) == 0) {
                /* XXX should do something with this */
                return 1;
        }

        /* Used only by the older login protocol */
        /* XXX remove this special case? */
        if (fr->conn->type == AIM_CONN_TYPE_AUTH) {
                return consumenonsnac(sess, fr, 0x0017, 0x0003);
        }

        tlvlist = aim_readtlvchain(&fr->data);

        if (aim_gettlv(tlvlist, 0x0009, 1)) {
                code = aim_gettlv16(tlvlist, 0x0009, 1);
        }

        if (aim_gettlv(tlvlist, 0x000b, 1)) {
                msg = aim_gettlv_str(tlvlist, 0x000b, 1);
        }

        if ((userfunc = aim_callhandler(sess, fr->conn, AIM_CB_FAM_SPECIAL, AIM_CB_SPECIAL_CONNERR))) {
                ret = userfunc(sess, fr, code, msg);
        }

        aim_freetlvchain(&tlvlist);

        g_free(msg);

        return ret;
}

/*
 * Some SNACs we do not allow to be hooked, for good reason.
 */
static int checkdisallowed(guint16 group, guint16 type)
{
        static const struct {
                guint16 group;
                guint16 type;
        } dontuse[] = {
                { 0x0001, 0x0002 },
                { 0x0001, 0x0003 },
                { 0x0001, 0x0006 },
                { 0x0001, 0x0007 },
                { 0x0001, 0x0008 },
                { 0x0001, 0x0017 },
                { 0x0001, 0x0018 },
                { 0x0000, 0x0000 }
        };
        int i;

        for (i = 0; dontuse[i].group != 0x0000; i++) {
                if ((dontuse[i].group == group) && (dontuse[i].type == type)) {
                        return 1;
                }
        }

        return 0;
}

int aim_conn_addhandler(aim_session_t *sess, aim_conn_t *conn, guint16 family, guint16 type,
                        aim_rxcallback_t newhandler, guint16 flags)
{
        struct aim_rxcblist_s *newcb;

        if (!conn) {
                return -1;
        }

        if (checkdisallowed(family, type)) {
                g_assert(0);
                return -1;
        }

        if (!(newcb = (struct aim_rxcblist_s *) g_new0(struct aim_rxcblist_s, 1))) {
                return -1;
        }

        newcb->family = family;
        newcb->type = type;
        newcb->flags = flags;
        newcb->handler = newhandler;
        newcb->next = NULL;

        if (!conn->handlerlist) {
                conn->handlerlist = (void *) newcb;
        } else {
                struct aim_rxcblist_s *cur;

                for (cur = (struct aim_rxcblist_s *) conn->handlerlist; cur->next; cur = cur->next) {
                        ;
                }
                cur->next = newcb;
        }

        return 0;
}

int aim_clearhandlers(aim_conn_t *conn)
{
        struct aim_rxcblist_s *cur;

        if (!conn) {
                return -1;
        }

        for (cur = (struct aim_rxcblist_s *) conn->handlerlist; cur; ) {
                struct aim_rxcblist_s *tmp;

                tmp = cur->next;
                g_free(cur);
                cur = tmp;
        }
        conn->handlerlist = NULL;

        return 0;
}

aim_rxcallback_t aim_callhandler(aim_session_t *sess, aim_conn_t *conn, guint16 family, guint16 type)
{
        struct aim_rxcblist_s *cur;

        if (!conn) {
                return NULL;
        }

        for (cur = (struct aim_rxcblist_s *) conn->handlerlist; cur; cur = cur->next) {
                if ((cur->family == family) && (cur->type == type)) {
                        return cur->handler;
                }
        }

        if (type == AIM_CB_SPECIAL_DEFAULT) {
                return NULL; /* prevent infinite recursion */
        }

        return aim_callhandler(sess, conn, family, AIM_CB_SPECIAL_DEFAULT);
}

static int aim_callhandler_noparam(aim_session_t *sess, aim_conn_t *conn, guint16 family, guint16 type,
                                   aim_frame_t *ptr)
{
        aim_rxcallback_t userfunc;

        if ((userfunc = aim_callhandler(sess, conn, family, type))) {
                return userfunc(sess, ptr);
        }

        return 1; /* XXX */
}

/*
 * aim_rxdispatch()
 *
 * Basically, heres what this should do:
 *   1) Determine correct packet handler for this packet
 *   2) Mark the packet handled (so it can be dequeued in purge_queue())
 *   3) Send the packet to the packet handler
 *   4) Go to next packet in the queue and start over
 *   5) When done, run purge_queue() to purge handled commands
 *
 * TODO: Clean up.
 * TODO: More support for mid-level handlers.
 * TODO: Allow for NULL handlers.
 *
 */
void aim_rxdispatch(aim_session_t *sess)
{
        int i;
        aim_frame_t *cur;

        for (cur = sess->queue_incoming, i = 0; cur; cur = cur->next, i++) {

                /*
                 * XXX: This is still fairly ugly.
                 */

                if (cur->handled) {
                        continue;
                }

                if (cur->hdr.flap.type == 0x01) {

                        cur->handled = aim_callhandler_noparam(sess, cur->conn, AIM_CB_FAM_SPECIAL,
                                                               AIM_CB_SPECIAL_FLAPVER, cur);                                      /* XXX use consumenonsnac */

                        continue;

                } else if (cur->hdr.flap.type == 0x02) {

                        if ((cur->handled = consumesnac(sess, cur))) {
                                continue;
                        }

                } else if (cur->hdr.flap.type == 0x04) {

                        cur->handled = negchan_middle(sess, cur);
                        continue;

                } else if (cur->hdr.flap.type == 0x05) {
                        ;
                }

                if (!cur->handled) {
                        consumenonsnac(sess, cur, 0xffff, 0xffff); /* last chance! */
                        cur->handled = 1;
                }
        }

        /*
         * This doesn't have to be called here.  It could easily be done
         * by a separate thread or something. It's an administrative operation,
         * and can take a while. Though the less you call it the less memory
         * you'll have :)
         */
        aim_purge_rxqueue(sess);

        return;
}