Hi Gowtham,
On Fri, Nov 7, 2014 at 3:06 PM, Gowtham Anandha Babu
<gowtham.ab@xxxxxxxxxxx> wrote:
> Changes made to decode RFCOMM hdr and print the same.
>
> RFCOMM: Unnumbered Info with Header Check (UIH)(0xef)
> Address: 0x01 cr 0 dlci 0x00
> Control: 0xef poll/final 0
> Length: 10
> FCS: 0xaa
> 81 11 20 e0 27 00 9a 02 00 07 aa .. .'......
>
> ---
> monitor/rfcomm.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 47 insertions(+), 3 deletions(-)
>
> diff --git a/monitor/rfcomm.c b/monitor/rfcomm.c
> index 155bde2..a70c404 100644
> --- a/monitor/rfcomm.c
> +++ b/monitor/rfcomm.c
> @@ -44,6 +44,11 @@
> #include "sdp.h"
> #include "rfcomm.h"
>
> +#define GET_LEN8(length) ((length & 0xfe) >> 1)
> +#define GET_LEN16(length) ((length & 0xfffe) >> 1)
> +#define GET_CR(type) ((type & 0x02) >> 1)
> +#define GET_PF(ctr) (((ctr) >> 4) & 0x1)
> +
> struct rfcomm_lhdr {
> uint8_t address;
> uint8_t control;
> @@ -57,6 +62,24 @@ struct rfcomm_frame {
> struct l2cap_frame l2cap_frame;
> };
>
> +static void print_rfcomm_hdr(struct rfcomm_frame *rfcomm_frame, uint8_t indent)
> +{
> + struct rfcomm_lhdr hdr = rfcomm_frame->hdr;
> +
> + /* Address field */
> + print_field("%*cAddress: 0x%2.2x cr %d dlci 0x%2.2x", indent, ' ',
> + hdr.address, GET_CR(hdr.address),
> + RFCOMM_GET_DLCI(hdr.address));
> +
> + /* Control field */
> + print_field("%*cControl: 0x%2.2x poll/final %d", indent, ' ',
> + hdr.control, GET_PF(hdr.control));
> +
> + /* Length and FCS */
> + print_field("%*cLength: %d", indent, ' ', hdr.length);
> + print_field("%*cFCS: 0x%2.2x", indent, ' ', hdr.fcs);
> +}
> +
> struct rfcomm_data {
> uint8_t frame;
> const char *str;
> @@ -73,12 +96,13 @@ static const struct rfcomm_data rfcomm_table[] = {
>
> void rfcomm_packet(const struct l2cap_frame *frame)
> {
> - uint8_t ctype;
> + uint8_t ctype, length, ex_length, indent = 1;
> const char *frame_str, *frame_color;
> struct l2cap_frame *l2cap_frame;
> struct rfcomm_frame rfcomm_frame;
> struct rfcomm_lhdr hdr;
> const struct rfcomm_data *rfcomm_data = NULL;
> + const void *ptr;
> int i;
>
> l2cap_frame_pull(&rfcomm_frame.l2cap_frame, frame, 0);
> @@ -89,9 +113,24 @@ void rfcomm_packet(const struct l2cap_frame *frame)
> goto fail;
>
> if (!l2cap_frame_get_u8(l2cap_frame, &hdr.address) ||
> - !l2cap_frame_get_u8(l2cap_frame, &hdr.control))
> + !l2cap_frame_get_u8(l2cap_frame, &hdr.control) ||
> + !l2cap_frame_get_u8(l2cap_frame, &length))
> goto fail;
>
> + /* length maybe 1 or 2 octets */
> + if (RFCOMM_TEST_EA(length))
> + hdr.length = (uint16_t) GET_LEN8(length);
> + else {
> + if (!l2cap_frame_get_u8(l2cap_frame, &ex_length))
> + goto fail;
> + hdr.length = ((uint16_t)length << 8) | ex_length;
> + hdr.length = GET_LEN16(hdr.length);
> + }
> +
> + /* fetching FCS by frame offset */
> + ptr = (l2cap_frame->data)+l2cap_frame->size-1;
> + hdr.fcs = *(uint8_t *)(ptr);
You should probably use l2cap_frame_pull followed by
l2cap_frame_get_u8 so we actually check if the frame is too short.
Btw, the format looks much better now.
> /* Decoding frame type */
> ctype = RFCOMM_GET_TYPE(hdr.control);
>
> @@ -122,7 +161,12 @@ void rfcomm_packet(const struct l2cap_frame *frame)
> "(0x%2.2x)", ctype);
>
> rfcomm_frame.hdr = hdr;
> - packet_hexdump(l2cap_frame->data, l2cap_frame->size);
> + print_rfcomm_hdr(&rfcomm_frame, indent);
> +
> + /* UIH frame */
> + if(ctype == 0xef)
> + packet_hexdump(l2cap_frame->data, l2cap_frame->size);
> +
> return;
>
> fail:
> --
> 1.9.1
>
> --
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--
Luiz Augusto von Dentz
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