Hi,
I wrote:
> > The lbuf usage is still needed, it's the reading buffer. unused_cell is
> > just a pointer that keeps tracks of pppoa3 progress into the read buffer
> > if there are still ATM cells left in.
>
> Then that should be changed back. The current patch doesn't seem to use
> lbuf at all.
Correction. unused_cells is initialised to lbuf at the first loop, and the
value of unused_cells is changed to atm_pointer by the call to
aal5_frame_from_atm_cells. This is probably a way to walk through lbuf. Ie
the use of unused_cells instead of lbuf makes sense. I'll have to look at this
a little closer, but I guess it is correct.
The lazy mans way to check if it behaves correctly is by using a small lbuf. Guess
I'll have a go at that ;) .
> > I have just a doubt about the case where:
> > - num_bytes_read < 0
> >
> > It seems to me, that this case should be checked and invalidate the
> > unused_cell data.
>
> Isn't unused_cells set to NULL by aal5_frame_from_atm_cell() after the
> whole frame has been processed?
Indeed unused_cells is set to NULL. Also I don't really get your point.
Whenever num_bytes_read is not zero -num_bytes_read will be smaller than 0...
The two checks whether pti == 1 can be merged. Dropping the "idiotic frame
length" check, using the constants from atm.h, renaming n1 to nb_cells,
moving the declaration of nb_cells inside the if (pti == 1) and simplifiying
the payload length calculation renders the following patch:
diff -pruN speedtouch.000/src/pppoa3.c speedtouch/src/pppoa3.c
--- speedtouch.000/src/pppoa3.c Tue Nov 18 10:39:35 2003
+++ speedtouch/src/pppoa3.c Tue Nov 18 12:13:08 2003
@@ -955,7 +955,8 @@ static void *read_from_usb_thread(void*
{
sigset_t signal_set;
- unsigned int pos;
+ int pos;
+ int num_bytes_read = 0;
unsigned char *buffer;
unsigned char *aal5_recv_buf;
unsigned char *destination_buf;
@@ -1002,10 +1003,11 @@ static void *read_from_usb_thread(void*
int n;
int pti;
- unsigned char lbuf[64*53];
+ int num_bytes_new;
+ unsigned char lbuf[64 * ATM_CELL_TOTAL_SIZE];
unsigned char *unused_cells;
- /* Reads 64*53 bytes from usb */
+ /* Reads 64 * ATM_CELL_TOTAL_SIZE bytes from usb */
do {
n = pusb_endpoint_read(ep_data, lbuf, sizeof(lbuf), 0);
} while (n < 0 && (errno == EINTR || errno == ETIMEDOUT));
@@ -1018,55 +1020,62 @@ static void *read_from_usb_thread(void*
/* Debug information */
report(2, REPORT_DEBUG|REPORT_DATE|REPORT_DUMP, "ATM cells read from
USB (%d bytes long)\n", lbuf, n, n);
- /* Accumulates data in the aal5_recv buffer */
- /* pti will be equal to the last cell pti */
- pti = aal5_frame_from_atm_cells(aal5_recv_buf, lbuf, n, my_vpi,
my_vci, &pos, &unused_cells);
-
- /* A buffer overflow has been detected */
- if(pti<0) {
- report(0, REPORT_ERROR|REPORT_DATE, "Buffer overflow, too many
cells for the same aal5 frame\n");
- pti = 0;
- }
+ num_bytes_read += n; /* save total number of bytes to be
processed */
+ num_bytes_new = n;
+ unused_cells = lbuf; /* point at start of lbuf */
+
+ /* Accumulate all cell-data in the aal5_recv buffer */
+ /* Depending on how many cells and what type, we have to loop one or
more times until everything */
+ /* has been dealt with. (for example we read:
cell-cell-cell-'end'cell-cell-cell-cell */
+ /* Every call to aal5_etc stops after finding an 'end'cell and then
pti = 1 ) 1 cell = 53 bytes */
+ while (unused_cells != NULL) {
+ pti = aal5_frame_from_atm_cells(aal5_recv_buf, unused_cells,
num_bytes_new, my_vpi, my_vci, &pos, &unused_cells);
+
+ /* 'pos' saves the place, where we are in the aal5_recv_buf */
+
+ /* A buffer overflow has been detected */
+ if (pti < 0) {
+ report(0, REPORT_ERROR|REPORT_DATE, "Buffer overflow,
too many cells for the same aal5 frame\n");
+ pti = 0;
+ }
- /* As the last pti is 1, we have to send the aal5_frame data */
- while(pti) {
+ /* pti = 0 (more frames to follow) or pti = 1 (end of
frame-group) */
+ /* When pti is 1, we have to send the aal5_frame data */
- /* Debug information */
- report(2, REPORT_DEBUG|REPORT_DATE|REPORT_DUMP, "AAL5 frame
joined up (%d bytes long)\n", aal5_recv_buf, pos, pos);
+ if (pti == 1) {
- /* Prepares the aal5 data (no overwrite is done)*/
- n = aal5_frame_dec(aal5_recv_buf, aal5_recv_buf, pos);
+ int nb_cells;
- if(n<0) {
+ /* Debug information */
+ report(2, REPORT_DEBUG|REPORT_DATE|REPORT_DUMP, "AAL5
frame joined up (%d bytes long)\n", aal5_recv_buf, pos, pos);
- report(0, REPORT_ERROR|REPORT_DATE, "CRC error in an
AAL5 frame\n");
+ /* Prepares the aal5 data (no overwrite is done)*/
+ n = aal5_frame_dec(aal5_recv_buf, aal5_recv_buf, pos);
- }
- else {
+ if (n < 0) {
+
+ report(0, REPORT_ERROR|REPORT_DATE, "CRC error
in AAL5 frame\n");
+ }
+ else {
+
+ report(2, REPORT_DEBUG|REPORT_DATE, "CRC okay
%d\n", n);
- /* Writes the result buffer */
+ /* Writes the result buffer */
#ifdef BRIDGING_ENABLED
- n += (bridging)?-BRIDGING1483_HEADER:HDLC_HEADER_SIZE;
+ n +=
(bridging)?-BRIDGING1483_HEADER:HDLC_HEADER_SIZE;
#else
- n += HDLC_HEADER_SIZE;
+ n += HDLC_HEADER_SIZE;
#endif
- if(write_dest(fdout, destination_buf, n) > 0)
- report(2, REPORT_DEBUG|REPORT_DATE, "Extracted
PPP packet sent to destination device\n\n");
-
- }
-
- /* Reinitializes pos and n*/
- pos = 0;
- pti = 0;
-
- /* Are cells unused in lbuf ? */
- if(unused_cells != NULL) {
+ if (write_dest(fdout, destination_buf, n) > 0)
+ report(2, REPORT_DEBUG|REPORT_DATE,
"Extracted PPP packet sent to destination device\n");
- int length;
+ }
- length = sizeof(lbuf) - (unused_cells - lbuf);
+ /* adjust the values of num_bytes_read based on pos */
- pti = aal5_frame_from_atm_cells(aal5_recv_buf,
unused_cells, length, my_vpi, my_vci, &pos, &unused_cells);
+ nb_cells = (pos / ATM_CELL_DATA_SIZE) *
ATM_CELL_TOTAL_SIZE; /* = actual length of payload-frames processed */
+ num_bytes_new = num_bytes_read -= nb_cells; /*
calculate the rest if there is any */
+ pos = 0;
}
---end of patch---
Bye,
Leonard.
--
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