Re: [Bluez-users] How do I obtain a free PSM automatically?

On Fri, 2003-02-07 at 21:25, Marcel Holtmann wrote:

Hi Alexandros,

quoted

I was assuming that the setting the psm field to zero would get you a 
dynamically assigned free PSM on the local host:

  addr.l2_family = AF_BLUETOOTH;
  bacpy(&addr.l2_bdaddr, BDADDR_ANY);  
  addr.l2_psm = htobs(0);

Calling bind() for this address succeeds.
Calling listen() afterwards fails and perror() gives: "Invalid argument"

you can't listen on PSM 0, because such PSM did not exists. You have to
choose one.

It would be nice if it had the expected semantics (i.e., those of IP sockets).
I think this is a bug.

In the meantime, here is some code:

   for (;;) {
      while (psm++ < 0xffff)
         if ((psm & 0x0001) && !(psm & 0x0100))
            break;
      if (psm == 0x10000) {
         // no resources
         close(s);
         return -EBUSY;
      }
      addr.l2_psm = htobs(psm);
      if (0 == bind(s, (struct sockaddr *)&addr, sizeof(addr)))
         break;
      if (errno != EADDRINUSE) {
         int e = -errno;
         close(s);
	 return e;
      }
   }

Enjoy,
Steve
-- 
Stephen Crane, Rococo Software Ltd. http://www.rococosoft.com
steve.crane@rococosoft.com +353-1-6601315 (ext 209)