Hi everyone.
I am trying do do a simple client server setup with bluez.
I can manage to have a client and a server on rfcomm sockets where the
server listen on a socket and accept a connection from the client by
connect. But then if I set the server back to accepting without putting
down the one client connection it doesn't accept a new connection.
When I read thought the documentation I can find on Bluez and Bluetooth
in general it seems like it should be possible to multiplex serveal
virtual rfcomm connections on one actual connection. But however I
really can get it working and can't find any code where they do
something similar.
Hope that someone can give me a hint...
/Kasper Revsbech
Here is a example of what I have tried to make it work:
Client:
--------------------------
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/rfcomm.h>
#define number_of_connections 5
int main(int argc, char **argv)
{
struct sockaddr_rc addr = { 0 };
int s[number_of_connections], status, getpeer_status;
char dest[18] = "00:11:67:05:4f:dc";
struct sockaddr peer_address;
int namelen = sizeof(peer_address),i;
// set the connection parameters (who to connect to)
addr.rc_family = AF_BLUETOOTH;
addr.rc_channel = (uint8_t) 1;
str2ba( dest, &addr.rc_bdaddr );
for (i=0 ;i=(number_of_connections-1);i++){
s[i] = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
/*connect to server*/
status = connect(s[i], (struct sockaddr *)&addr, sizeof(addr));
// send a message
if( status == 0 ) {
status = write(s[i], "hello!", 6);
}
if( status < 0 ) perror("uh oh");
}
for (i=0 ;i=(number_of_connections-1);i++){
close(s[i]);
}
return 0;
}
-----------------------------------
Server:
-----------------------------------
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/rfcomm.h>
#define number_of_connections 5
int main(int argc, char **argv)
{
struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 };
char buf[1024] = { 0 };
int s, client[number_of_connections], bytes_read;
socklen_t opt = sizeof(rem_addr);
int i;
// allocate socket
s = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
// bind socket to port 1 of the first available
// local bluetooth adapter
loc_addr.rc_family = AF_BLUETOOTH;
loc_addr.rc_bdaddr = *BDADDR_ANY;
loc_addr.rc_channel = (uint8_t) 1;
bind(s, (struct sockaddr *)&loc_addr, sizeof(loc_addr));
// put socket into listening mode
listen(s, number_of_connections);
for (i=0 ;i=(number_of_connections-1);i++){
// accept one connection
client[i] = accept(s, (struct sockaddr *)&rem_addr, &opt);
ba2str( &rem_addr.rc_bdaddr, buf );
fprintf(stderr, "accepted connection from %s\n", buf);
memset(buf, 0, sizeof(buf));
// read data from the client
bytes_read = read(client[i], buf, sizeof(buf));
if( bytes_read > 0 ) {
printf("received [%s]\n", buf);
}
}
// close connection
for (i=0 ;i=(number_of_connections-1);i++){
close(client[i]);
}
close(s);
return 0;
Hi Kasper,
>>> I am trying do do a simple client server setup with bluez.
>>> I can manage to have a client and a server on rfcomm sockets where
>>> the server listen on a socket and accept a connection from the
>>> client by connect. But then if I set the server back to accepting
>>> without putting down the one client connection it doesn't accept a
>>> new connection.
>>> When I read thought the documentation I can find on Bluez and
>>> Bluetooth in general it seems like it should be possible to
>>> multiplex serveal virtual rfcomm connections on one actual
>>> connection. But however I really can get it working and can't find
>>> any code where they do something similar.
>>>
>>
>> are the clients running on multiple adapters.If they run on the
>> sameadapter, it won't work. RFCOMM is not a layer that assign dynamic
>> channels numbers to each connection (like L2CAP does) and thus once a
>> RFCOMM channel is in use (the pair is bdaddr:channel) then you can
>> connect to it twice.
>>
>>
> Exactly the client sockets are all originated from the same adapter.
> What I want to do is by some libsocks tricks to emulate a native tcp/
> ip socket and provide nearly the same interface. So far I have been
> using RFCOMM. As I understand you, this setup with multiple sockets
> connections from each host is possible using a l2cap socket instead.
> Which leads into the next question. Reading documentation on
> Bluetooth stacks in general some seems to provide a SOCK_STREAM type
> using l2cap. However this does not seems to be the case in the Bluez
> stack. So is there a way to have a somehow reliable stream
> connection allowing multiple connections from each host?
RFCOMM is SOCK_STREAM and L2CAP is SOCK_SEQPACKET. If someone
implements L2CAP retransmission and flow-control we could have
SOCK_STREAM for L2CAP, too.
Regards
Marcel
Marcel Holtmann skrev:
> Hi Kasper,
>
>
>> I am trying do do a simple client server setup with bluez.
>> I can manage to have a client and a server on rfcomm sockets where the
>> server listen on a socket and accept a connection from the client by
>> connect. But then if I set the server back to accepting without putting
>> down the one client connection it doesn't accept a new connection.
>> When I read thought the documentation I can find on Bluez and Bluetooth
>> in general it seems like it should be possible to multiplex serveal
>> virtual rfcomm connections on one actual connection. But however I
>> really can get it working and can't find any code where they do
>> something similar.
>>
>
> are the clients running on multiple adapters.If they run on the sameadapter, it won't work. RFCOMM is not a layer that assign dynamic
> channels numbers to each connection (like L2CAP does) and thus once a
> RFCOMM channel is in use (the pair is bdaddr:channel) then you can
> connect to it twice.
>
>
Exactly the client sockets are all originated from the same adapter.
What I want to do is by some libsocks tricks to emulate a native tcp/ip
socket and provide nearly the same interface. So far I have been using
RFCOMM. As I understand you, this setup with multiple sockets
connections from each host is possible using a l2cap socket instead.
Which leads into the next question. Reading documentation on Bluetooth
stacks in general some seems to provide a SOCK_STREAM type using l2cap.
However this does not seems to be the case in the Bluez stack. So is
there a way to have a somehow reliable stream connection allowing
multiple connections from each host?
Regards and thanks a lot
Kasper Revsbech
Hi Kasper,
> I am trying do do a simple client server setup with bluez.
> I can manage to have a client and a server on rfcomm sockets where the
> server listen on a socket and accept a connection from the client by
> connect. But then if I set the server back to accepting without putting
> down the one client connection it doesn't accept a new connection.
> When I read thought the documentation I can find on Bluez and Bluetooth
> in general it seems like it should be possible to multiplex serveal
> virtual rfcomm connections on one actual connection. But however I
> really can get it working and can't find any code where they do
> something similar.
are the clients running on multiple adapters. If they run on the same
adapter, it won't work. RFCOMM is not a layer that assign dynamic
channels numbers to each connection (like L2CAP does) and thus once a
RFCOMM channel is in use (the pair is bdaddr:channel) then you can
connect to it twice.
Regards
Marcel