source: protocols/oscar/rxqueue.c @ a0bd4c2

/*
 *  aim_rxqueue.c
 *
 * This file contains the management routines for the receive
 * (incoming packet) queue.  The actual packet handlers are in
 * aim_rxhandlers.c.
 */

#include <aim.h> 

#ifndef _WIN32
#include <sys/socket.h>
#endif

/*
 *
 */
int aim_recv(int fd, void *buf, size_t count)
{
        int left, cur; 

        for (cur = 0, left = count; left; ) {
                int ret;
                
                ret = recv(fd, ((unsigned char *)buf)+cur, left, 0);

                /* Of course EOF is an error, only morons disagree with that. */
                if (ret <= 0)
                        return -1;

                cur += ret;
                left -= ret;
        }

        return cur;
}

/*
 * Read into a byte stream.  Will not read more than count, but may read
 * less if there is not enough room in the stream buffer.
 */
static int aim_bstream_recv(aim_bstream_t *bs, int fd, size_t count)
{
        int red = 0;

        if (!bs || (fd < 0) || (count < 0))
                return -1;
        
        if (count > (bs->len - bs->offset))
                count = bs->len - bs->offset; /* truncate to remaining space */

        if (count) {

                red = aim_recv(fd, bs->data + bs->offset, count);

                if (red <= 0)
                        return -1;
        }

        bs->offset += red;

        return red;
}

int aim_bstream_init(aim_bstream_t *bs, guint8 *data, int len)
{
        
        if (!bs)
                return -1;

        bs->data = data;
        bs->len = len;
        bs->offset = 0;

        return 0;
}

int aim_bstream_empty(aim_bstream_t *bs)
{
        return bs->len - bs->offset;
}

int aim_bstream_curpos(aim_bstream_t *bs)
{
        return bs->offset;
}

int aim_bstream_setpos(aim_bstream_t *bs, int off)
{

        if (off > bs->len)
                return -1;

        bs->offset = off;

        return off;
}

void aim_bstream_rewind(aim_bstream_t *bs)
{

        aim_bstream_setpos(bs, 0);

        return;
}

int aim_bstream_advance(aim_bstream_t *bs, int n)
{

        if (aim_bstream_empty(bs) < n)
                return 0; /* XXX throw an exception */

        bs->offset += n;

        return n;
}

guint8 aimbs_get8(aim_bstream_t *bs)
{
        
        if (aim_bstream_empty(bs) < 1)
                return 0; /* XXX throw an exception */
        
        bs->offset++;
        
        return aimutil_get8(bs->data + bs->offset - 1);
}

guint16 aimbs_get16(aim_bstream_t *bs)
{
        
        if (aim_bstream_empty(bs) < 2)
                return 0; /* XXX throw an exception */
        
        bs->offset += 2;
        
        return aimutil_get16(bs->data + bs->offset - 2);
}

guint32 aimbs_get32(aim_bstream_t *bs)
{
        
        if (aim_bstream_empty(bs) < 4)
                return 0; /* XXX throw an exception */
        
        bs->offset += 4;
        
        return aimutil_get32(bs->data + bs->offset - 4);
}

guint8 aimbs_getle8(aim_bstream_t *bs)
{
        
        if (aim_bstream_empty(bs) < 1)
                return 0; /* XXX throw an exception */
        
        bs->offset++;
        
        return aimutil_getle8(bs->data + bs->offset - 1);
}

guint16 aimbs_getle16(aim_bstream_t *bs)
{
        
        if (aim_bstream_empty(bs) < 2)
                return 0; /* XXX throw an exception */
        
        bs->offset += 2;
        
        return aimutil_getle16(bs->data + bs->offset - 2);
}

guint32 aimbs_getle32(aim_bstream_t *bs)
{
        
        if (aim_bstream_empty(bs) < 4)
                return 0; /* XXX throw an exception */
        
        bs->offset += 4;
        
        return aimutil_getle32(bs->data + bs->offset - 4);
}

int aimbs_put8(aim_bstream_t *bs, guint8 v)
{

        if (aim_bstream_empty(bs) < 1)
                return 0; /* XXX throw an exception */

        bs->offset += aimutil_put8(bs->data + bs->offset, v);

        return 1;
}

int aimbs_put16(aim_bstream_t *bs, guint16 v)
{

        if (aim_bstream_empty(bs) < 2)
                return 0; /* XXX throw an exception */

        bs->offset += aimutil_put16(bs->data + bs->offset, v);

        return 2;
}

int aimbs_put32(aim_bstream_t *bs, guint32 v)
{

        if (aim_bstream_empty(bs) < 4)
                return 0; /* XXX throw an exception */

        bs->offset += aimutil_put32(bs->data + bs->offset, v);

        return 1;
}

int aimbs_putle8(aim_bstream_t *bs, guint8 v)
{

        if (aim_bstream_empty(bs) < 1)
                return 0; /* XXX throw an exception */

        bs->offset += aimutil_putle8(bs->data + bs->offset, v);

        return 1;
}

int aimbs_putle16(aim_bstream_t *bs, guint16 v)
{

        if (aim_bstream_empty(bs) < 2)
                return 0; /* XXX throw an exception */

        bs->offset += aimutil_putle16(bs->data + bs->offset, v);

        return 2;
}

int aimbs_putle32(aim_bstream_t *bs, guint32 v)
{

        if (aim_bstream_empty(bs) < 4)
                return 0; /* XXX throw an exception */

        bs->offset += aimutil_putle32(bs->data + bs->offset, v);

        return 1;
}

int aimbs_getrawbuf(aim_bstream_t *bs, guint8 *buf, int len)
{

        if (aim_bstream_empty(bs) < len)
                return 0;

        memcpy(buf, bs->data + bs->offset, len);
        bs->offset += len;

        return len;
}

guint8 *aimbs_getraw(aim_bstream_t *bs, int len)
{
        guint8 *ob;

        if (!(ob = g_malloc(len)))
                return NULL;

        if (aimbs_getrawbuf(bs, ob, len) < len) {
                g_free(ob);
                return NULL;
        }

        return ob;
}

char *aimbs_getstr(aim_bstream_t *bs, int len)
{
        guint8 *ob;

        if (!(ob = g_malloc(len+1)))
                return NULL;

        if (aimbs_getrawbuf(bs, ob, len) < len) {
                g_free(ob);
                return NULL;
        }
        
        ob[len] = '\0';

        return (char *)ob;
}

int aimbs_putraw(aim_bstream_t *bs, const guint8 *v, int len)
{

        if (aim_bstream_empty(bs) < len)
                return 0; /* XXX throw an exception */

        memcpy(bs->data + bs->offset, v, len);
        bs->offset += len;

        return len;
}

int aimbs_putbs(aim_bstream_t *bs, aim_bstream_t *srcbs, int len)
{

        if (aim_bstream_empty(srcbs) < len)
                return 0; /* XXX throw exception (underrun) */

        if (aim_bstream_empty(bs) < len)
                return 0; /* XXX throw exception (overflow) */

        memcpy(bs->data + bs->offset, srcbs->data + srcbs->offset, len);
        bs->offset += len;
        srcbs->offset += len;

        return len;
}

/**
 * aim_frame_destroy - free aim_frame_t 
 * @frame: the frame to free  
 *
 * returns -1 on error; 0 on success.  
 *
 */
void aim_frame_destroy(aim_frame_t *frame)
{

        g_free(frame->data.data); /* XXX aim_bstream_free */

        g_free(frame);
} 


/*
 * Grab a single command sequence off the socket, and enqueue
 * it in the incoming event queue in a seperate struct.
 */
int aim_get_command(aim_session_t *sess, aim_conn_t *conn)
{
        guint8 flaphdr_raw[6];
        aim_bstream_t flaphdr;
        aim_frame_t *newrx;
        guint16 payloadlen;
        
        if (!sess || !conn)
                return 0;

        if (conn->fd == -1)
                return -1; /* its a aim_conn_close()'d connection */

        /* KIDS, THIS IS WHAT HAPPENS IF YOU USE CODE WRITTEN FOR GUIS IN A DAEMON!
           
           And wouldn't it make sense to return something that prevents this function
           from being called again IMMEDIATELY (and making the program suck up all
           CPU time)?...
           
        if (conn->fd < 3)
                return 0;
        */

        if (conn->status & AIM_CONN_STATUS_INPROGRESS)
                return aim_conn_completeconnect(sess, conn);

        aim_bstream_init(&flaphdr, flaphdr_raw, sizeof(flaphdr_raw));

        /*
         * Read FLAP header.  Six bytes:
         *    
         *   0 char  -- Always 0x2a
         *   1 char  -- Channel ID.  Usually 2 -- 1 and 4 are used during login.
         *   2 short -- Sequence number 
         *   4 short -- Number of data bytes that follow.
         */
        if (aim_bstream_recv(&flaphdr, conn->fd, 6) < 6) {
                aim_conn_close(conn);
                return -1;
        }

        aim_bstream_rewind(&flaphdr);

        /*
         * This shouldn't happen unless the socket breaks, the server breaks,
         * or we break.  We must handle it just in case.
         */
        if (aimbs_get8(&flaphdr) != 0x2a) {
                guint8 start;

                aim_bstream_rewind(&flaphdr);
                start = aimbs_get8(&flaphdr);
                imcb_error(sess->aux_data, "FLAP framing disrupted");
                aim_conn_close(conn);
                return -1;
        }       

        /* allocate a new struct */
        if (!(newrx = (aim_frame_t *)g_new0(aim_frame_t,1)))
                return -1;

        /* we're doing FLAP if we're here */
        newrx->hdrtype = AIM_FRAMETYPE_FLAP;
        
        newrx->hdr.flap.type = aimbs_get8(&flaphdr);
        newrx->hdr.flap.seqnum = aimbs_get16(&flaphdr);
        payloadlen = aimbs_get16(&flaphdr);

        newrx->nofree = 0; /* free by default */

        if (payloadlen) {
                guint8 *payload = NULL;

                if (!(payload = (guint8 *) g_malloc(payloadlen))) {
                        aim_frame_destroy(newrx);
                        return -1;
                }

                aim_bstream_init(&newrx->data, payload, payloadlen);

                /* read the payload */
                if (aim_bstream_recv(&newrx->data, conn->fd, payloadlen) < payloadlen) {
                        aim_frame_destroy(newrx); /* free's payload */
                        aim_conn_close(conn);
                        return -1;
                }
        } else
                aim_bstream_init(&newrx->data, NULL, 0);


        aim_bstream_rewind(&newrx->data);

        newrx->conn = conn;

        newrx->next = NULL;  /* this will always be at the bottom */

        if (!sess->queue_incoming)
                sess->queue_incoming = newrx;
        else {
                aim_frame_t *cur;

                for (cur = sess->queue_incoming; cur->next; cur = cur->next)
                        ;
                cur->next = newrx;
        }

        newrx->conn->lastactivity = time(NULL);

        return 0;  
}

/*
 * Purge recieve queue of all handled commands (->handled==1).  Also
 * allows for selective freeing using ->nofree so that the client can
 * keep the data for various purposes.  
 *
 * If ->nofree is nonzero, the frame will be delinked from the global list, 
 * but will not be free'ed.  The client _must_ keep a pointer to the
 * data -- libfaim will not!  If the client marks ->nofree but
 * does not keep a pointer, it's lost forever.
 *
 */
void aim_purge_rxqueue(aim_session_t *sess)
{
        aim_frame_t *cur, **prev;

        for (prev = &sess->queue_incoming; (cur = *prev); ) {
                if (cur->handled) {

                        *prev = cur->next;
                        
                        if (!cur->nofree)
                                aim_frame_destroy(cur);

                } else
                        prev = &cur->next;
        }

        return;
}

/*
 * Since aim_get_command will aim_conn_kill dead connections, we need
 * to clean up the rxqueue of unprocessed connections on that socket.
 *
 * XXX: this is something that was handled better in the old connection
 * handling method, but eh.
 */
void aim_rxqueue_cleanbyconn(aim_session_t *sess, aim_conn_t *conn)
{
        aim_frame_t *currx;

        for (currx = sess->queue_incoming; currx; currx = currx->next) {
                if ((!currx->handled) && (currx->conn == conn))
                        currx->handled = 1;
        }       
        return;
}