Re: [PATCH v1 2/5] monitor/rfcomm: Add support for RPN frame decoding

[Szymon Janc <szymon.janc@tieto.com>]

Hi Gowtham,

On Friday 05 of December 2014 16:14:20 Gowtham Anandha Babu wrote:
> Hi Szymon,
> 
> > -----Original Message-----
> > From: linux-bluetooth-owner@vger.kernel.org [mailto:linux-bluetooth-
> > owner@vger.kernel.org] On Behalf Of Szymon Janc
> > Sent: Thursday, December 04, 2014 8:48 PM
> > To: Gowtham Anandha Babu
> > Cc: linux-bluetooth@vger.kernel.org; d.kasatkin@samsung.com;
> > bharat.panda@samsung.com; cpgs@samsung.com
> > Subject: Re: [PATCH v1 2/5] monitor/rfcomm: Add support for RPN frame
> > decoding
> > 
> > Hi Gowtham,
> > 
> > On Wed, Dec 3, 2014 at 1:01 PM, Gowtham Anandha Babu
> > <gowtham.ab@samsung.com> wrote:
> > > Changes made to decode RPN frame in RFCOMM for btmon.
> > >
> > >       RFCOMM: Unnumbered Info with Header Check (UIH)(0xef)
> > >          Address: 0x03 cr 1 dlci 0x00
> > >          Control: 0xef poll/final 0
> > >          Length: 10
> > >          FCS: 0x70
> > >          MCC Message type: Remote Port Negotiation Command CMD(0x24)
> > >            Length: 8
> > >            dlci 32
> > >            br 3 db 2 sb 0 p 0 pt 0 xi 0 xo 0
> > >            rtri 0 rtro 0 rtci 0 rtco 0 xon 17 xoff 19
> > >            pm 0x3f7f
> > > ---
> > >  monitor/rfcomm.c | 73
> > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 73 insertions(+)
> > >
> > > diff --git a/monitor/rfcomm.c b/monitor/rfcomm.c index
> > > cd50c8c..62b52cc 100644
> > > --- a/monitor/rfcomm.c
> > > +++ b/monitor/rfcomm.c
> > > @@ -63,6 +63,18 @@ static char *cr_str[] = {
> > >  #define GET_V24_IC(sigs)       ((sigs & 0x40) >> 6)
> > >  #define GET_V24_DV(sigs)       ((sigs & 0x80) >> 7)
> > >
> > > +/* RPN macros */
> > > +#define GET_RPN_DB(parity)     (parity & 0x03)
> > > +#define GET_RPN_SB(parity)     ((parity & 0x04) >> 2)
> > > +#define GET_RPN_PARITY(parity) ((parity & 0x08) >> 3) #define
> > > +GET_RPN_PTYPE(parity)  ((parity & 0x03) >> 3)
> > > +#define GET_RPN_XIN(io)                (io & 0x01)
> > > +#define GET_RPN_XOUT(io)       ((io & 0x02) >> 1)
> > > +#define GET_RPN_RTRI(io)       ((io & 0x04) >> 2)
> > > +#define GET_RPN_RTRO(io)       ((io & 0x08) >> 3)
> > > +#define GET_RPN_RTCI(io)       ((io & 0x10) >> 4)
> > > +#define GET_RPN_RTCO(io)       ((io & 0x20) >> 5)
> > > +
> > >  struct rfcomm_lhdr {
> > >         uint8_t address;
> > >         uint8_t control;
> > > @@ -77,6 +89,16 @@ struct rfcomm_lmsc {
> > >         uint8_t break_sig;
> > >  } __attribute__((packed));
> > >
> > > +struct rfcomm_rpn {
> > > +       uint8_t dlci;
> > > +       uint8_t bit_rate;
> > > +       uint8_t parity;
> > > +       uint8_t io;
> > > +       uint8_t xon;
> > > +       uint8_t xoff;
> > > +       uint16_t pm;
> > > +} __attribute__ ((packed));
> > > +
> > >  struct rfcomm_lmcc {
> > >         uint8_t type;
> > >         uint16_t length;
> > > @@ -138,6 +160,55 @@ done:
> > >         return true;
> > >  }
> > >
> > > +static inline bool mcc_rpn(struct rfcomm_frame *rfcomm_frame, uint8_t
> > > +indent) {
> > > +       struct l2cap_frame *frame = &rfcomm_frame->l2cap_frame;
> > > +       struct rfcomm_rpn rpn;
> > > +
> > > +       if (!l2cap_frame_get_u8(frame, &rpn.dlci))
> > > +               return false;
> > > +
> > > +       print_field("%*cdlci %d", indent, ' ',
> > > + RFCOMM_GET_DLCI(rpn.dlci));
> > > +
> > > +       if (frame->size < 7)
> > > +               goto done;
> > > +
> > > +       /* port value octets (optional) */
> > > +
> > > +       if (!l2cap_frame_get_u8(frame, &rpn.bit_rate))
> > > +               return false;
> > > +
> > > +       if (!l2cap_frame_get_u8(frame, &rpn.parity))
> > > +               return false;
> > > +
> > > +       if (!l2cap_frame_get_u8(frame, &rpn.io))
> > > +               return false;
> > > +
> > > +       print_field("%*cbr %d db %d sb %d p %d pt %d xi %d xo %d",
> indent, '
> > ',
> > > +               rpn.bit_rate, GET_RPN_DB(rpn.parity),
> GET_RPN_SB(rpn.parity),
> > > +               GET_RPN_PARITY(rpn.parity), GET_RPN_PTYPE(rpn.parity),
> > > +               GET_RPN_XIN(rpn.io), GET_RPN_XOUT(rpn.io));
> > > +
> > > +       if (!l2cap_frame_get_u8(frame, &rpn.xon))
> > > +               return false;
> > > +
> > > +       if (!l2cap_frame_get_u8(frame, &rpn.xoff))
> > > +               return false;
> > > +
> > > +       print_field("%*crtri %d rtro %d rtci %d rtco %d xon %d xoff %d",
> > > +               indent, ' ', GET_RPN_RTRI(rpn.io), GET_RPN_RTRO(rpn.io),
> > > +               GET_RPN_RTCI(rpn.io), GET_RPN_RTCO(rpn.io), rpn.xon,
> > > +               rpn.xoff);
> > > +
> > > +       if (!l2cap_frame_get_be16(frame, &rpn.pm))
> > > +               return false;
> > > +
> > > +       print_field("%*cpm 0x%04x", indent, ' ', __bswap_16(rpn.pm));
> > 
> > This __bswap_16 is invalid since rpn.pm was already converted to host
> order
> > by l2cap_frame_get_be16(). (It wouldn't work correctly on BE arch anyway).
> > 
> > Also this was causing build problems under Android. If you are able to
> build-
> > test under Android please do so. If not then at least point this in cover
> letter
> > or patch comment that code was tested only under Linux).
> > 
> > I've fixed this myself but please pay attention to this with any future
> > submission.
> > 
> 
> Sure I will mention the tested platform details for future submission.
> 
> Btw without __bswap_16(), rpn.pm and pn.mtu will be different from the
> hcidump logs.
> 
> This is captured by removing __bswap_16().
> 
> Btmon log:
>       RFCOMM: Unnumbered Info with Header Check (UIH)(0xef)
>          Address: 0x03 cr 1 dlci 0x00
>          Control: 0xef poll/final 0
>          Length: 10
>          FCS: 0x70
>          MCC Message type: DLC Parameter Negotiation CMD(0x20)
>            Length: 8
>            dlci 6 frame_type 0 credit_flow 15 pri 3
>            ack_timer 0 frame_size 32256 max_retrans 0 credits 1
> 
> Hcidump log:
>       RFCOMM(s): PN CMD: cr 1 dlci 0 pf 0 ilen 10 fcs 0x70 mcc_len 8
>       dlci 6 frame_type 0 credit_flow 15 pri 3 ack_timer 0
>       frame_size 126 max_retrans 0 credits 1
> 
> The rpn.pm is fine. That may be printed without doing __bswap_16() also.
> 
> But in the above PN frame, frame_size is different from actual hcidump
> trace.
> I cross checked with PTS logs, it was same as the hcidump trace.
> So, if it is causing build problems under Android, use
> l2cap_frame_get_le16()
> Instead of l2cap_frame_get_be16() for pn.mtu. 
> 
> If we are consistent with hcidump, then replace the be16() by le16() for
> both pn.mtu and rpn.pm.
> 
> After replacing the le16() function:
> Btmon logs looks like:
> 
>       RFCOMM: Unnumbered Info with Header Check (UIH)(0xef)
>          Address: 0x03 cr 1 dlci 0x00
>          Control: 0xef poll/final 0
>          Length: 10
>          FCS: 0x70
>          MCC Message type: DLC Parameter Negotiation CMD(0x20)
>            Length: 8
>            dlci 6 frame_type 0 credit_flow 15 pri 3
>            ack_timer 0 frame_size 126 max_retrans 0 credits 1
> 
> What do you think ?

If value is LE then l2cap_frame_get_le16() should be used.
(Same issue affects rpn.pm mcc_rpn(), right?)

> 
> > > +
> > > +done:
> > > +       return true;
> > > +}
> > > +
> > >  struct mcc_data {
> > >         uint8_t type;
> > >         const char *str;
> > > @@ -201,6 +272,8 @@ static inline bool mcc_frame(struct rfcomm_frame
> > *rfcomm_frame, uint8_t indent)
> > >         switch (type) {
> > >         case RFCOMM_MSC:
> > >                 return mcc_msc(rfcomm_frame, indent+2);
> > > +       case RFCOMM_RPN:
> > > +               return mcc_rpn(rfcomm_frame, indent+2);
> > >         default:
> > >                 packet_hexdump(frame->data, frame->size);
> > >         }
> > > --
> > > 1.9.1
> > >
> > > --
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> > > linux-bluetooth" in the body of a message to majordomo@vger.kernel.org
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> > 
> > 
> > 
> > --
> > pozdrawiam
> > Szymon K. Janc
> > szymon.janc@gmail.com
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-bluetooth"
> in
> > the body of a message to majordomo@vger.kernel.org More majordomo
> > info at  http://vger.kernel.org/majordomo-info.html
> 
> 
> Regards,
> Gowtham Anandha Babu
> 
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-- 
Best regards, 
Szymon Janc