RE: [PATCH 1/5] monitor/rfcomm.c: Add support for MSC frame decoding

[Gowtham Anandha Babu <gowtham.ab@samsung.com>]

Hi Luiz,

> -----Original Message-----
> From: linux-bluetooth-owner@vger.kernel.org [mailto:linux-bluetooth-
> owner@vger.kernel.org] On Behalf Of Luiz Augusto von Dentz
> Sent: Tuesday, December 02, 2014 8:41 PM
> To: Gowtham Anandha Babu
> Cc: linux-bluetooth@vger.kernel.org; Dmitry Kasatkin; Bharat Panda;
> cpgs@samsung.com
> Subject: Re: [PATCH 1/5] monitor/rfcomm.c: Add support for MSC frame
> decoding
> 
> Hi Gowtham,
> 
> On Tue, Dec 2, 2014 at 4:39 PM, Gowtham Anandha Babu
> <gowtham.ab@samsung.com> wrote:
> > Hi Luiz,
> >
> >> -----Original Message-----
> >> From: linux-bluetooth-owner@vger.kernel.org [mailto:linux-bluetooth-
> >> owner@vger.kernel.org] On Behalf Of Luiz Augusto von Dentz
> >> Sent: Tuesday, December 02, 2014 6:11 PM
> >> To: Gowtham Anandha Babu
> >> Cc: linux-bluetooth@vger.kernel.org; Dmitry Kasatkin; Bharat Panda;
> >> cpgs@samsung.com
> >> Subject: Re: [PATCH 1/5] monitor/rfcomm.c: Add support for MSC frame
> >> decoding
> >>
> >> Hi Gowtham,
> >>
> >> On Tue, Dec 2, 2014 at 2:37 PM, Gowtham Anandha Babu
> >> <gowtham.ab@samsung.com> wrote:
> >> > Hi Luiz,
> >> >
> >> >> -----Original Message-----
> >> >> From: Gowtham Anandha Babu [mailto:gowtham.ab@samsung.com]
> >> >> Sent: Tuesday, December 02, 2014 4:30 PM
> >> >> To: 'Luiz Augusto von Dentz'
> >> >> Cc: 'linux-bluetooth@vger.kernel.org'; 'Dmitry Kasatkin'; 'Bharat
> >> >> Panda'; 'cpgs@samsung.com'
> >> >> Subject: RE: [PATCH 1/5] monitor/rfcomm.c: Add support for MSC
> >> >> frame decoding
> >> >>
> >> >> Hi Luiz,
> >> >>
> >> >> > -----Original Message-----
> >> >> > From: linux-bluetooth-owner@vger.kernel.org
> >> >> > [mailto:linux-bluetooth- owner@vger.kernel.org] On Behalf Of
> >> >> > Luiz Augusto von Dentz
> >> >> > Sent: Tuesday, December 02, 2014 4:22 PM
> >> >> > To: Gowtham Anandha Babu
> >> >> > Cc: linux-bluetooth@vger.kernel.org; Dmitry Kasatkin; Bharat
> >> >> > Panda; cpgs@samsung.com
> >> >> > Subject: Re: [PATCH 1/5] monitor/rfcomm.c: Add support for MSC
> >> >> > frame decoding
> >> >> >
> >> >> > Hi Gowtham,
> >> >> >
> >> >> > On Tue, Dec 2, 2014 at 11:37 AM, Gowtham Anandha Babu
> >> >> > <gowtham.ab@samsung.com> wrote:
> >> >> > > Changes made to decode MSC frame in RFCOMM for btmon.
> >> >> > >
> >> >> > >       RFCOMM: Unnumbered Info with Header Check (UIH)(0xef)
> >> >> > >          Address: 0x01 cr 0 dlci 0x00
> >> >> > >          Control: 0xef poll/final 0
> >> >> > >          Length: 4
> >> >> > >          FCS: 0xaa
> >> >> > >          MCC Message type: Modem Status Command CMD(0x38)
> >> >> > >            Length: 2
> >> >> > >            dlci 32
> >> >> > >            fc 0 rtc 1 rtr 1 ic 0 dv 1
> >> >> > > ---
> >> >> > >  monitor/rfcomm.c | 76
> >> >> > > ++++++++++++++++++++++++++++++++++++++++++++++++++--
> ---
> >> -
> >> >> > >  1 file changed, 69 insertions(+), 7 deletions(-)
> >> >> > >
> >> >> > > diff --git a/monitor/rfcomm.c b/monitor/rfcomm.c index
> >> >> > > b3db98b..969b29f 100644
> >> >> > > --- a/monitor/rfcomm.c
> >> >> > > +++ b/monitor/rfcomm.c
> >> >> > > @@ -49,11 +49,24 @@ static char *cr_str[] = {
> >> >> > >         "CMD"
> >> >> > >  };
> >> >> > >
> >> >> > > -#define CR_STR(type) cr_str[GET_CR(type)] -#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)
> >> >> > > +/* RFCOMM frame parsing macros */
> >> >> > > +#define CR_STR(type)           cr_str[GET_CR(type)]
> >> >> > > +#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)
> >> >> > > +
> >> >> > > +/* MSC macros */
> >> >> > > +#define GET_V24_FC(sigs)       ((sigs & 0x02) >> 1)
> >> >> > > +#define GET_V24_RTC(sigs)      ((sigs & 0x04) >> 2)
> >> >> > > +#define GET_V24_RTR(sigs)      ((sigs & 0x08) >> 3)
> >> >> > > +#define GET_V24_IC(sigs)       ((sigs & 0x40) >> 6)
> >> >> > > +#define GET_V24_DV(sigs)       ((sigs & 0x80) >> 7)
> >> >> > > +
> >> >> > > +#define GET_BRK_SIG1(sigs)     ((sigs & 0x02) >> 1)
> >> >> > > +#define GET_BRK_SIG2(sigs)     ((sigs & 0x04) >> 2)
> >> >> > > +#define GET_BRK_SIG3(sigs)     ((sigs & 0x08) >> 3)
> >> >> > > +#define GET_BRK_SIG_LEN(sigs)  ((sigs & 0xf0) >> 4)
> >> >> > >
> >> >> > >  struct rfcomm_lhdr {
> >> >> > >         uint8_t address;
> >> >> > > @@ -63,6 +76,12 @@ struct rfcomm_lhdr {
> >> >> > >         uint8_t credits; /* only for UIH frame */  }
> >> >> > > __attribute__((packed));
> >> >> > >
> >> >> > > +struct rfcomm_lmsc {
> >> >> > > +       uint8_t dlci;
> >> >> > > +       uint8_t v24_sig;
> >> >> > > +       uint8_t break_sig;
> >> >> > > +} __attribute__((packed));
> >> >> > > +
> >> >> > >  struct rfcomm_lmcc {
> >> >> > >         uint8_t type;
> >> >> > >         uint16_t length;
> >> >> > > @@ -92,6 +111,43 @@ static void print_rfcomm_hdr(struct
> >> >> rfcomm_frame
> >> >> > *rfcomm_frame, uint8_t indent)
> >> >> > >         print_field("%*cFCS: 0x%2.2x", indent, ' ', hdr.fcs);
> >> >> > > }
> >> >> > >
> >> >> > > +static inline bool mcc_msc(struct rfcomm_frame *rfcomm_frame,
> >> >> > > +uint8_t
> >> >> > > +indent) {
> >> >> > > +       struct l2cap_frame *frame = &rfcomm_frame->l2cap_frame;
> >> >> > > +       struct rfcomm_lmsc msc;
> >> >> > > +
> >> >> > > +       if (!l2cap_frame_get_u8(frame, &msc.dlci))
> >> >> > > +               return false;
> >> >> > > +
> >> >> > > +       print_field("%*cdlci %d ", indent, ' ',
> >> >> > > + RFCOMM_GET_DLCI(msc.dlci));
> >> >> > > +
> >> >> > > +       if (!l2cap_frame_get_u8(frame, &msc.v24_sig))
> >> >> > > +               return false;
> >> >> > > +
> >> >> > > +       /* v24 control signals */
> >> >> > > +       print_field("%*cfc %d rtc %d rtr %d ic %d dv %d", indent, ' ',
> >> >> > > +               GET_V24_FC(msc.v24_sig), GET_V24_RTC(msc.v24_sig),
> >> >> > > +               GET_V24_RTR(msc.v24_sig), GET_V24_IC(msc.v24_sig),
> >> >> > > +
> >> >> > > + GET_V24_DV(msc.v24_sig));
> >> >> > > +
> >> >> > > +       if (frame->size < 2)
> >> >> > > +               goto done;
> >> >> > > +
> >> >> > > +       /* break signals (optional) */
> >> >> > > +
> >> >> > > +       if (!l2cap_frame_get_u8(frame, &msc.break_sig))
> >> >> > > +               return false;
> >> >> > > +
> >> >> > > +       printf("%2.2x", msc.break_sig);
> >> >> >
> >> >> > Im very suspicious the printf above will break indentation, you
> >> >> > better add a frame that does exercise this code to make sure it
> >> >> > is not
> >> happening.
> >> >> >
> >> >>
> >> >> That printf was added to cross check the break signals.
> >> >> I Forgot to remove that line. Will update in v2.
> >> >>
> >> >
> >> > I tried testing with many test cases, not able to capture the break
> signals.
> >> > Any suggestions to capture the break signals?
> >> > Btw the implementation here is exactly same as in hcidump.
> >>
> >> Perhaps you can try some test case with PTS, please check the TS if
> >> there is a TC that tests break signals.
> >>
> >
> > I referred the RFCOMM TS and tried all test cases for RFCOMM in PTS, still
> not able to capture the break signals.
> > In the RFCOMM specs also, break signal fields are not explained much.
> > Meanwhile I tried executing the MAP, PBAP, OPP, FTP connection
> establishment test cases, nothing worked out.
> >
> > Since this is optional, can we skip this (break signal decoding) for now? Or
> what do you think?
> 
> Then skip it and add a TODO to the code.
> 

I skipped this for now and updated the TODO in v1 and submitted the same.
Please have a look at it.

> 
> --
> Luiz Augusto von Dentz
> --
> 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