capi.c

讲述linux的初始化过程

        *((ushort*) skb_put(*skb, 2) ) = chan->callref;  

        *(skb_put(*skb, 1)) = chan->layer2link;
        *(skb_put(*skb, 1)) = chan->r_refnum;

        return (*skb)->len;
}

int capi_disc_req(ushort callref, struct sk_buff **skb, u_char cause)
{

	if ((*skb = dev_alloc_skb(6)) == NULL) {
    
		printk(KERN_WARNING "capi_disc_req: alloc_skb failed\n");
		return -1;
	}

        *((ushort*) skb_put(*skb, 2) ) = callref;  

        *(skb_put(*skb, 1)) = 2;                  /* Cause.Length = 2; */
        *(skb_put(*skb, 1)) = 0x80;
        *(skb_put(*skb, 1)) = 0x80 | cause;           

        /* 
         * Change it: we should send 'Sic transit gloria Mundi' here ;-) 
         */

        *(skb_put(*skb, 1)) = 0;                   /* UTUS.Length = 0;  */

        return 6;
}

int capi_disc_resp(struct pcbit_chan *chan, struct sk_buff **skb)
{
	if ((*skb = dev_alloc_skb(2)) == NULL) {
    
		printk(KERN_WARNING "capi_disc_resp: alloc_skb failed\n");
		return -1;
	}

        *((ushort*) skb_put(*skb, 2)) = chan->callref;  

        return 2;
}


/*
 *  Decoding of CAPI messages
 *
 */

int capi_decode_conn_ind(struct pcbit_chan * chan, 
                         struct sk_buff *skb,
                         struct callb_data *info) 
{
        int CIlen, len;

        /* Call Reference [CAPI] */
        chan->callref = *((ushort*) skb->data);
        skb_pull(skb, 2);

#ifdef DEBUG
	printk(KERN_DEBUG "Call Reference: %04x\n", chan->callref); 
#endif

        /* Channel Identification */

        /* Expect  
           Len = 1 
           Octect 3 = 0100 10CC - [ 7 Basic, 4 , 2-1 chan ]
           */

        CIlen = skb->data[0];
#ifdef DEBUG
        if (CIlen == 1) {

                if ( ((skb->data[1]) & 0xFC) == 0x48 )
                        printk(KERN_DEBUG "decode_conn_ind: chan ok\n");
                printk(KERN_DEBUG "phyChan = %d\n", skb->data[1] & 0x03); 
        }
	else
		printk(KERN_DEBUG "conn_ind: CIlen = %d\n", CIlen);
#endif
        skb_pull(skb, CIlen + 1);

        /* Calling Party Number */
        /* An "additional service" as far as Portugal Telecom is concerned */

        len = skb->data[0];

	if (len > 0) {
		int count = 1;
		
#ifdef DEBUG
		printk(KERN_DEBUG "CPN: Octect 3 %02x\n", skb->data[1]);
#endif
		if ((skb->data[1] & 0x80) == 0)
			count = 2;
		
		if (!(info->data.setup.CallingPN = kmalloc(len - count + 1, GFP_ATOMIC)))
			return -1;
       
		memcpy(info->data.setup.CallingPN, skb->data + count + 1, 
		       len - count);
		info->data.setup.CallingPN[len - count] = 0;

	}
	else {
		info->data.setup.CallingPN = NULL;
		printk(KERN_DEBUG "NULL CallingPN\n");
	}

	skb_pull(skb, len + 1);

        /* Calling Party Subaddress */
        skb_pull(skb, skb->data[0] + 1);

        /* Called Party Number */

        len = skb->data[0];

	if (len > 0) {
		int count = 1;
		
		if ((skb->data[1] & 0x80) == 0)
			count = 2;
        
		if (!(info->data.setup.CalledPN = kmalloc(len - count + 1, GFP_ATOMIC)))
			return -1;
        
		memcpy(info->data.setup.CalledPN, skb->data + count + 1, 
		       len - count); 
		info->data.setup.CalledPN[len - count] = 0;

	}
	else {
		info->data.setup.CalledPN = NULL;
		printk(KERN_DEBUG "NULL CalledPN\n");
	}

	skb_pull(skb, len + 1);

        /* Called Party Subaddress */
        skb_pull(skb, skb->data[0] + 1);

        /* LLC */
        skb_pull(skb, skb->data[0] + 1);

        /* HLC */
        skb_pull(skb, skb->data[0] + 1);

        /* U2U */
        skb_pull(skb, skb->data[0] + 1);

        return 0;
}

/*
 *  returns errcode
 */

int capi_decode_conn_conf(struct pcbit_chan * chan, struct sk_buff *skb,
			  int *complete) 
{
        int errcode;
  
        chan->callref = *((ushort *) skb->data);     /* Update CallReference */
        skb_pull(skb, 2);

        errcode = *((ushort *) skb->data);   /* read errcode */
        skb_pull(skb, 2);

        *complete = *(skb->data);
        skb_pull(skb, 1);

        /* FIX ME */
        /* This is actually a firmware bug */
        if (!*complete)
        {
                printk(KERN_DEBUG "complete=%02x\n", *complete);
                *complete = 1;
        }


        /* Optional Bearer Capability */
        skb_pull(skb, *(skb->data) + 1);
        
        /* Channel Identification */
        skb_pull(skb, *(skb->data) + 1);

        /* High Layer Compatibility follows */
        skb_pull(skb, *(skb->data) + 1);

        return errcode;
}

int capi_decode_conn_actv_ind(struct pcbit_chan * chan, struct sk_buff *skb)
{
        ushort len;
#ifdef DEBUG
        char str[32];
#endif

        /* Yet Another Bearer Capability */
        skb_pull(skb, *(skb->data) + 1);
  

        /* Connected Party Number */
        len=*(skb->data);

#ifdef DEBUG
	if (len > 1 && len < 31) {
		memcpy(str, skb->data + 2, len - 1);
		str[len] = 0;
		printk(KERN_DEBUG "Connected Party Number: %s\n", str);
	}
	else
		printk(KERN_DEBUG "actv_ind CPN len = %d\n", len);
#endif

        skb_pull(skb, len + 1);

        /* Connected Subaddress */
        skb_pull(skb, *(skb->data) + 1);

        /* Low Layer Capability */
        skb_pull(skb, *(skb->data) + 1);

        /* High Layer Capability */
        skb_pull(skb, *(skb->data) + 1);

        return 0;
}

int capi_decode_conn_actv_conf(struct pcbit_chan * chan, struct sk_buff *skb)
{
        ushort errcode;

        errcode = *((ushort*) skb->data);
        skb_pull(skb, 2);
        
        /* Channel Identification 
        skb_pull(skb, skb->data[0] + 1);
        */
        return errcode;
}


int capi_decode_sel_proto_conf(struct pcbit_chan *chan, struct sk_buff *skb)
{
        ushort errcode;
        
        chan->layer2link = *(skb->data);
        skb_pull(skb, 1);

        errcode = *((ushort*) skb->data);
        skb_pull(skb, 2);

        return errcode;
}

int capi_decode_actv_trans_conf(struct pcbit_chan *chan, struct sk_buff *skb)
{
        ushort errcode;

        if (chan->layer2link != *(skb->data) )
                printk("capi_decode_actv_trans_conf: layer2link doesn't match\n");

        skb_pull(skb, 1);

        errcode = *((ushort*) skb->data);
        skb_pull(skb, 2);

        return errcode;        
}

int capi_decode_disc_ind(struct pcbit_chan *chan, struct sk_buff *skb)
{
        ushort len;
#ifdef DEBUG
        int i;
#endif
        /* Cause */
        
        len = *(skb->data);
        skb_pull(skb, 1);

#ifdef DEBUG

        for (i=0; i<len; i++)
                printk(KERN_DEBUG "Cause Octect %d: %02x\n", i+3, 
                       *(skb->data + i));
#endif

        skb_pull(skb, len);

        return 0;
}

int capi_decode_disc_conf(struct pcbit_chan *chan, struct sk_buff *skb)
{
        ushort errcode;

        errcode = *((ushort*) skb->data);
        skb_pull(skb, 2);

        return errcode;                
}

#ifdef DEBUG
int capi_decode_debug_188(u_char *hdr, ushort hdrlen)
{
        char str[64];
        int len;
        
        len = hdr[0];

        if (len < 64 && len == hdrlen - 1) {        
                memcpy(str, hdr + 1, hdrlen - 1);
                str[hdrlen - 1] = 0;
                printk("%s\n", str);
        }
        else
                printk("debug message incorrect\n");

        return 0;
}
#endif