Sample Programs
Connectionless Mode
/************************************************************************** main
**************************************************************************/
main() {
int | send_fd, recv_fd; | /* | file descriptors */ |
u_char | sdlsap[20]; | /* | sending DLSAP */ |
u_char | rdlsap[20]; | /* | receiving DLSAP */ |
int | sdlsap_len, rdlsap_len; /* | DLSAP lengths */ | |
int | i, j, recv_len; |
|
|
/*
PART 1 of program. Demonstrate connectionless data transfer with LLC SAP header.
*/
/*
First, we must open the DLPI device file, /dev/dlpi, and attach to a PPA. attach() will open /dev/dlpi, find the first PPA with the DL_HP_PPA_INFO primitive, and attach to that PPA. attach() returns the file descriptor for the stream. Here we do an attach for each file descriptor.
*/
send_fd = attach(); recv_fd = attach();
/*
Now we have to bind to a IEEESAP. We will ask for connectionless data link service with the DL_CLDLS service mode. Since we are connectionless, we will not have any incoming connections so we
set max_conind to 0. bind() will return our local DLSAP and its length in the last two arguments we pass to it.
*/
bind(send_fd, SEND_SAP, 0, DL_CLDLS, sdlsap, &sdlsap_len); bind(recv_fd, RECV_SAP, 0, DL_CLDLS, rdlsap, &rdlsap_len);
/* print the DLSAPs we got back from the binds */ print_dlsap(”sending DLSAP = ”, sdlsap, sdlsap_len); print_dlsap(”receiving DLSAP = ”, rdlsap, rdlsap_len);
/*
Time to send some data. We'll send 5 data packets in sequence. */
for(i = 0; i < 5; i++) {
/* send (i+1)*10 data bytes with the first byte = i */ data_area[0] = i;
/* Initialize data area */ for (j = 1; j < (i+1)*10; j++)
data_area[j] = ”a”; print_dlsap(”sending data to ”,rdlsap, rdlsap_len);
send_data(send_fd, rdlsap, rdlsap_len, (i + 1) * 10); /* receive the data packet */
recv_len = recv_data(recv_fd);
printf(”received %d bytes, first word = %d\n”, recv_len, data_area[0]);
}
164 | Appendix A |
