Hello,
I have tried to understand how to open an L2CAP socket, and have used the
BlueZ API. This is what I have got so far:
/*
* l2cap_listen(l2cap_channel)
* Use this channel as a listening post
*/
static int l2cap_listen(const bdaddr_t *bdaddr, unsigned short psm, int lm,
int backlog)
{
struct sockaddr_l2 addr;
struct l2cap_options opts;
int sk;
/* allocate a free socket */
if ((sk = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP)) < 0)
return -1;
/* open connection to remote device */
memset(&addr, 0, sizeof(addr));
addr.l2_family = AF_BLUETOOTH;
bacpy(&addr.l2_bdaddr, bdaddr); /* update source address of socket */
addr.l2_psm = htobs(psm);
/* bind socket to newly formed socket */
if (bind(sk, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
perror("ERROR: Could not bind socket");
close(sk);
return -1;
}
setsockopt(sk, SOL_L2CAP, L2CAP_LM, &lm, sizeof(lm));
memset(&opts, 0, sizeof(opts));
opts.imtu = HIDP_DEFAULT_MTU;
opts.omtu = HIDP_DEFAULT_MTU;
opts.flush_to = 0xffff;
setsockopt(sk, SOL_L2CAP, L2CAP_OPTIONS, &opts, sizeof(opts));
/* backlog: specifies the number of unaccepted connection
* that the system will allow before refusing new connections
*/
if (listen(sk, backlog) < 0) {
close(sk);
return -1;
}
return sk;
}
/*
* l2cap_connect_req()
* Establishes connection with specific socket
* Request to establish connection from remote
* communication partner.
* Such a socket has to have been previously created
* by an application with the command listen.
*/
static int l2cap_connect(bdaddr_t *src, bdaddr_t *dst, unsigned short psm)
{
struct sockaddr_l2 addr;
struct l2cap_options opts;
int sk;
/* socket allocation */
if ((sk = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP)) < 0)
perror("ERROR: Could not create socket");
return -1;
memset(&addr, 0, sizeof(addr));
addr.l2_family = AF_BLUETOOTH;
bacpy(&addr.l2_bdaddr, src); /*update source address of socket */
/* binds socket to psm */
if (bind(sk, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
close(sk);
return -1;
}
memset(&opts, 0, sizeof(opts));
opts.imtu = HIDP_DEFAULT_MTU;
opts.omtu = HIDP_DEFAULT_MTU;
opts.flush_to = 0xffff;
setsockopt(sk, SOL_L2CAP, L2CAP_OPTIONS, &opts, sizeof(opts));
memset(&addr, 0, sizeof(addr));
addr.l2_family = AF_BLUETOOTH;
bacpy(&addr.l2_bdaddr, dst);
addr.l2_psm = htobs(psm);
if (connect(sk, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
close(sk);
return -1;
}
return sk;
}
/*
* l2cap_accept()
* (Permits incoming connection)
* Blocks and accepts incoming connection
* Function switches from BT_LISTEN to BT_CONNECTED
*/
static int l2cap_accept(int sk, bdaddr_t *bdaddr)
{
struct sockaddr_l2 addr;
socklen_t addrlen;
int nsk;
memset(&addr, 0, sizeof(addr));
addrlen = sizeof(addr);
// accept one connection
if ((nsk = accept(sk, (struct sockaddr *) &addr, &addrlen)) < 0)
return -1;
if (bdaddr)
bacpy(bdaddr, &addr.l2_bdaddr);
return nsk;
}
--------------------
I am eventually aiming to register the mouse HID events, and send it via the
L2CAP socket to "control" another bluetooth-enabled PC.
How do I use an SDP service in conjunction with the existing L2CAP code? How
do I use the control channel (L2CAP_PSM_HIDP_CTRL 0x11) and the interrupt
channel (L2CAP_PSM_HIDP_INTR 0x13)
I think the control channel is used by SDP for signalling, (device
discovery); the interrupt channel is used for data transfer (service
discovery)
Thanks in advance for any help!
On 4/3/07, Meenakshi Seeballack <[email protected]> wrote:
> Hello,
> I have tried to understand how to open an L2CAP socket, and have used the
> BlueZ API. This is what I have got so far:
> /*
> * l2cap_listen(l2cap_channel)
> * Use this channel as a listening post
> */
> static int l2cap_listen(const bdaddr_t *bdaddr, unsigned short psm, int lm,
> int backlog)
> {
> struct sockaddr_l2 addr;
> struct l2cap_options opts;
> int sk;
>
> /* allocate a free socket */
> if ((sk = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP)) < 0)
> return -1;
>
> /* open connection to remote device */
> memset(&addr, 0, sizeof(addr));
> addr.l2_family = AF_BLUETOOTH;
> bacpy(&addr.l2_bdaddr, bdaddr); /* update source address of socket */
> addr.l2_psm = htobs(psm);
>
> /* bind socket to newly formed socket */
> if (bind(sk, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
> perror("ERROR: Could not bind socket");
> close(sk);
> return -1;
> }
>
> setsockopt(sk, SOL_L2CAP, L2CAP_LM, &lm, sizeof(lm));
>
> memset(&opts, 0, sizeof(opts));
> opts.imtu = HIDP_DEFAULT_MTU;
> opts.omtu = HIDP_DEFAULT_MTU;
> opts.flush_to = 0xffff;
>
> setsockopt(sk, SOL_L2CAP, L2CAP_OPTIONS, &opts, sizeof(opts));
>
> /* backlog: specifies the number of unaccepted connection
> * that the system will allow before refusing new connections
> */
> if (listen(sk, backlog) < 0) {
> close(sk);
> return -1;
> }
>
> return sk;
> }
>
> /*
> * l2cap_connect_req()
> * Establishes connection with specific socket
> * Request to establish connection from remote
> * communication partner.
> * Such a socket has to have been previously created
> * by an application with the command listen.
> */
> static int l2cap_connect(bdaddr_t *src, bdaddr_t *dst, unsigned short psm)
> {
> struct sockaddr_l2 addr;
> struct l2cap_options opts;
> int sk;
>
> /* socket allocation */
> if ((sk = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP)) < 0)
> perror("ERROR: Could not create socket");
> return -1;
>
> memset(&addr, 0, sizeof(addr));
> addr.l2_family = AF_BLUETOOTH;
> bacpy(&addr.l2_bdaddr, src); /*update source address of socket */
>
> /* binds socket to psm */
> if (bind(sk, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
> close(sk);
> return -1;
> }
>
> memset(&opts, 0, sizeof(opts));
> opts.imtu = HIDP_DEFAULT_MTU;
> opts.omtu = HIDP_DEFAULT_MTU;
> opts.flush_to = 0xffff;
>
> setsockopt(sk, SOL_L2CAP, L2CAP_OPTIONS, &opts, sizeof(opts));
>
> memset(&addr, 0, sizeof(addr));
> addr.l2_family = AF_BLUETOOTH;
> bacpy(&addr.l2_bdaddr, dst);
> addr.l2_psm = htobs(psm);
>
> if (connect(sk, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
> close(sk);
> return -1;
> }
>
> return sk;
> }
>
> /*
> * l2cap_accept()
> * (Permits incoming connection)
> * Blocks and accepts incoming connection
> * Function switches from BT_LISTEN to BT_CONNECTED
> */
> static int l2cap_accept(int sk, bdaddr_t *bdaddr)
> {
> struct sockaddr_l2 addr;
> socklen_t addrlen;
> int nsk;
>
> memset(&addr, 0, sizeof(addr));
> addrlen = sizeof(addr);
>
> // accept one connection
> if ((nsk = accept(sk, (struct sockaddr *) &addr, &addrlen)) < 0)
> return -1;
>
> if (bdaddr)
> bacpy(bdaddr, &addr.l2_bdaddr);
>
> return nsk;
> }
> --------------------
> I am eventually aiming to register the mouse HID events, and send it via the
> L2CAP socket to "control" another bluetooth-enabled PC.
> How do I use an SDP service in conjunction with the existing L2CAP code? How
> do I use the control channel (L2CAP_PSM_HIDP_CTRL 0x11) and the interrupt
> channel (L2CAP_PSM_HIDP_INTR 0x13)
> I think the control channel is used by SDP for signalling, (device
> discovery); the interrupt channel is used for data transfer (service
> discovery)
> Thanks in advance for any help!
>
>
> -------------------------------------------------------------------------
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>
Hi Meenakshi,
Check the D-Bus Input service implementation: utils/input
It contains the code that you want.
BR,
Claudio.
--
---------------------------------------------------------
Claudio Takahasi
Instituto Nokia de Tecnologia - INdT
-------------------------------------------------------------------------
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