/****************************************************************************
* get_ticket
* get a ticket from the license server
* Results: 0 for success, -1 for failure
*/
int get_ticket()
{
char *response;
char buf[MSGLEN];
if(have_ticket) /* don't be greedy */
return(0);
sprintf(buf, "HELO %d", pid); /* compose request */
if ( (response = do_transaction(buf)) == NULL )
return(-1);
/* parse the response and see if we got a ticket.
* on success, the message is: TICK ticket-string
* on failure, the message is: FAIL failure-msg
*/
if ( strncmp(response, "TICK", 4) == 0 ){
strcpy(ticket_buf, response + 5); /* grab ticket-id */
have_ticket = 1; /* set this flag */
narrate("got ticket", ticket_buf);
return(0);
}
if ( strncmp(response,"FAIL",4) == 0)
narrate("Could not get ticket",response);
else
narrate("Unknown message:", response);
return(-1);
} /* get_ticket */
/*******************************************************************
* get_ticket
* get a ticket from the license server
* Result: 0 for scuccess, -1 for failure
*/
int get_ticket() {
char *response;
char buf[MSGLEN];
if(have_ticket)
return 0; // dont' be greedy
sprintf(buf,"HELLO %d",pid);
if((response = do_transaction(buf)) == NULL) {
return -1;
}
/* parse the response and if we got a ticket.
* on success,the message is: TICK ticket-string
* on failure,the message is: FAIL failute-msg
*/
if(strncmp(response,"TICK",4) == 0) {
strcpy(ticket_buf,response + 5);; // grab ticket -id
have_ticket = 1; // set the flag
narrate("got ticket",ticket_buf);
return 0;
}
if(strncmp(response,"FAIL",4) == 0)
narrate("Could not get ticket",response);
else
narrate("Unknowm message:",response);
return -1;
}// get_ticket
// release_ticket: give a ticket back to the server
int release_ticket()
{
char * response;
char buf[MSGLEN];
if (!have_ticket)
return(0);
sprintf(buf, "GBYE %s", ticket_buf);
if ((response = do_transcation(buf)) == NULL)
return(-1);
// parse the response and see if we give a ticket success
if (strncmp(response, "THNX", 4) == 0)
{
have_ticket = 0;
narrate("release a ticket", "");
return(0);
}
if (strncmp(response, "FAIL", 4) == 0)
narrate("release failed", response+5);
else
narrate("Unknown message:", response);
return(-1);
}
/****************************************************************************
* release_ticket
* Give a ticket back to the server
* Results: 0 for success, -1 for failure
*/
int release_ticket()
{
char buf[MSGLEN];
char *response;
if(!have_ticket) /* don't have a ticket */
return(0); /* nothing to release */
sprintf(buf, "GBYE %s", ticket_buf); /* compose message */
if ( (response = do_transaction(buf)) == NULL )
return(-1);
/* examine response
* success: THNX info-string
* failure: FAIL error-string
*/
if ( strncmp(response, "THNX", 4) == 0 ){
narrate("released ticket OK","");
return 0;
}
if ( strncmp(response, "FAIL", 4) == 0)
narrate("release failed", response+5);
else
narrate("Unknown message:", response);
return(-1);
} /* release_ticket */
// get_ticket: get a ticket from server
int get_ticket()
{
char * response;
char buf[MSGLEN];
if (have_ticket)
return(0);
sprintf(buf, "HELO %d", pid);
if ((response = do_transcation(buf)) == NULL)
return(-1);
// parse the response and see if we got a ticket
if (strncmp(response, "TICK", 4) == 0)
{
strcpy(ticket_buf, response+5);
have_ticket = 1;
printf("ticket_buf %s\n", ticket_buf);
narrate("got ticket", ticket_buf);
return(0);
}
if (strncmp(response, "FAIL", 4) == 0)
narrate("Could not get ticket", response);
else
narrate("Unknown message:", response);
return(-1);
}
/*******************************************************************
* do_validate
* validate the ticket that hold on
* Result: 0 for success, -1 for failure
*/
int do_validate() {
char buf[BUFSIZ];
char *response;
sprintf(buf,"VALD %s",ticket_buf);
if((response = do_transaction(buf)) == NULL)
return -1;
/* parse the response and see if we the ticket is valid
* on success, the message is: GOOD vaild-msg
* on failure, the message is: FIAL failure-msg
*/
if(strncmp(response,"GOOD",4) == 0) {
narrate("Validate success",ticket_buf);
return 0;
}
if(strncmp(response,"FAIL",4) == 0)
narrate("Invalid ticket",response);
else
narrate("Unknown message:",response);
return -1;
}
int main(void) {
struct sockaddr_in clnt_addr;
socklen_t addrlen = sizeof(clnt_addr);
int ret;
char buf[MSGLEN];
unsigned int time_left;
int sock_fd = setup();
signal(SIGALRM, ticket_reclaim);
alarm(RECLAIM_INTERVAL);
while (true) {
ret = recvfrom(sock_fd, buf, MSGLEN, 0, (struct sockaddr *)&clnt_addr, &addrlen);
if (ret != -1) {
buf[ret] = '\0';
narrate("GOT:", buf, &clnt_addr);
time_left = alarm(0);
handle_request(buf, &clnt_addr, addrlen);
alarm(time_left);
}
else {
if (errno != EINTR)
perror("recvfrom");
}
}
return EXIT_SUCCESS;
}
int main(int ac, char *av[])
{
struct sockaddr_in client_addr;
socklen_t addrlen;
char buf[MSGLEN];
int ret;
int sock;
unsigned time_left;
void ticket_reclaim();
sock = setup();
signal(SIGALRM, ticket_reclaim);
alarm(RECLAIM_INTERVAL);
while (1) {
addrlen = sizeof(client_addr);
ret = recvfrom(sock, buf, MSGLEN, 0,
(struct sockaddr *)&client_addr, &addrlen);
if (ret != -1) {
buf[ret] = '\0';
narrate("GOT:", buf, &client_addr);
time_left = alarm(0);
handle_request(buf, &client_addr, addrlen);
alarm(time_left);
} else if (errno != EINTR)
perror("recvfrom");
}
}
/****************************************************************************
* * do_hello
* * Give out a ticket if any are available
* * IN msg_p message received from client
* * Results: ptr to response
* * NOTE: return is in static buffer overwritten by each call
* */
static char *do_hello(char *msg_p)
{
int x;
static char replybuf[MSGLEN];
if(num_tickets_out >= MAXUSERS)
return("FAIL no tickets available");
/* else find a free ticket and give it to client */
for(x = 0; x<MAXUSERS && ticket_array[x] != TICKET_AVAIL; x++)
;
/* A sanity check - should never happen */
if(x == MAXUSERS) {
narrate("database corrupt","",NULL);
return("FAIL database corrupt");
}
/* Found a free ticket. Record "name" of user (pid) in array.
* * generate ticket of form: pid.slot
* */
ticket_array[x] = atoi(msg_p + 5); /* get pid in msg */
sprintf(replybuf, "TICK %d.%d", ticket_array[x], x);
num_tickets_out++;
return(replybuf);
} /* do_hello */
char *do_goodbye(char *msg){
int pid, slot;
if((sscanf((msg+5), "%d. %d", &pid, &slot) != 2) ||
(ticket_array[slot] != pid)){
narrate("Bogus ticket", msg+5, NULL);
return "FAIL invalid ticket";
}
ticket_array[slot] = TICKET_AVAIL;
num_tickets_out--;
return "THAX See ya!";
}
/****************************************************************************
* * do_validate
* * Validate client's ticket
* * IN msg_p message received from client
* * Results: ptr to response
* */
static char *do_validate(char *msg)
{
int pid, slot; /* components of ticket */
/* msg looks like VAD pid.slot - parse it and validate */
if (sscanf(msg+5,"%d.%d",&pid,&slot)==2 && ticket_array[slot] == pid)
return("GOOD Valid ticket");
/* bad ticket */
narrate("Bogus ticket", msg+5, NULL);
return("FAIL invalid ticket");
}
/*******************************************************************
* do_validate
* Validate client's ticket
* IN msg_p message from client
* Result: ptr to response
* NOTE: return is in staitc buffer over written by each call
*/
static char *do_validate(char *msg) {
int pid,slot; // components of ticket
// message looks like VALD pid.slot
if(sscanf(msg + 5,"%d.%d",&pid,&slot) == 2
&& ticket_array[slot] == pid)
return "GOOD Valid ticket";
// bad ticket
narrate("Bogus ticket",msg + 5,NULL);
return "FAIL invalid ticket";
}
void ticket_reclaim(){
int i;
char tick[BUFSIZ];
for(i=0; i<MAXUSERS; i++){
if((ticket_array[i] != TICKET_AVAIL) && (kill(ticket_array[i], 0) == -1) && (errno == ESRCH)){
sprintf(tick, "%d. %d", ticket_array[i], i);
narrate("freeing", tick, NULL);
ticket_array[i] = TICKET_AVAIL;
num_ticket_out--;
}
}
alarm(RECLAIM_INTERVAL);
}
handle_request(char *req, struct sockaddr_in *client, socklen_t addlen){
fprintf(stderr, "In handle_request\n"); fflush(stderr);
char *response;
int ret;
if(strncmp(req, "HELO", 4) == 0)
response = do_hello(req);
else if(strncmp(req, "GBYE", 4) == 0)
response = do_goodbye(req);
else
response = "FAIL invalid request";
narrate("SAID:", response, client);
ret = sendto(sd, response, strlen(response), 0, client, addlen);
if(ret == -1)
perror("SERVER sendto failed");
}
/****************************************************************************
* * ticket_reclaim
* * go through all tickets and reclaim ones belonging to dead processes
* * Results: none
* */
void ticket_reclaim()
{
int i;
char tick[BUFSIZ];
for(i = 0; i < MAXUSERS; i++) {
if((ticket_array[i] != TICKET_AVAIL) &&
(kill(ticket_array[i], 0) == -1) && (errno == ESRCH)) {
/* Process is gone - free up slot */
sprintf(tick, "%d.%d", ticket_array[i],i);
narrate("freeing", tick, NULL);
ticket_array[i] = TICKET_AVAIL;
num_tickets_out--;
}
}
alarm(RECLAIM_INTERVAL); /* reset alarm clock */
}
/* handle_request(request, clientaddr, addrlen)
* branch on code in request
*/
handle_request(char *req, struct sockaddr_in *client, socklen_t addlen)
{
char *response;
int ret;
/* act and compose a response */
if (strncmp(req, "HELO", 4) == 0)
response = do_hello(req);
else if(strncmp(req, "GBYE", 4) == 0)
response = do_goodbye(req);
else
response = "FAIL invalid request";
/* send the response to the client */
narrate("SAID:", response, client);
ret = sendto(sd, response, strlen(response), 0, client, addlen);
if (ret == -1)
perror("SERVER sendto failed");
}
/*******************************************************************
* ticket_reclaim
* go through all tickets and reclaim ones belonging to dead processes
* Result: none
*/
void ticket_reclaim() {
int i;
char tick[BUFSIZ];
for(i = 0; i < MAXUSERS; ++i) {
if(ticket_array[i] != TICKET_AVAIL
&& (kill(ticket_array[i],0) == -1)
&& errno == ESRCH) {
// Proccess is gone - free up slot
sprintf(tick,"%d.%d",ticket_array[i],i);
narrate("freeing",tick,NULL);
ticket_array[i] = TICKET_AVAIL;
--num_tickets_out;
}
}
alarm(RECLAIM_INTERVAL); // reset alarm clock
} // ticket_reclaim
char *do_hello(char *msg){
fprintf(stderr, "In do_hello\n"); fflush(stderr);
int x;
static char replybuf[MSGLEN];
if(num_tickets_out >= MAXUSERS)
return "FAIL no tickets available";
fprintf(stderr, "before search\n"); fflush(stderr);
for(x=0; x<MAXUSERS && ticket_array[x]!=TICKET_AVAIL; x++);
if(x == MAXUSERS){
narrate("db corrupt", "", NULL);
return "FAIL db corrupt";
}
fprintf(stderr, "befor atoi\n"); fflush(stderr);
ticket_array[x] = atoi(msg+5);
sprintf(replybuf, "TICK %d. %d", ticket_array[x], x);
num_tickets_out++;
return replybuf;
}
/* take back ticket client is returning
* IN msg_p message received from client
* results: ptr to response
* note: return is in static buffer overwritten by each call
*/
char *do_goodbye(char *msg_p)
{
int pid, slot; /* components of ticket */
/* the user's giving us back a ticket. first we need to
* get the ticket out of the message, which looks like:
*
* GBYE pid.slot
* */
if ((sscanf((msg_p + 5), "%d.%d", &pid, &slot) != 2) ||
(ticket_array[slot] != pid)) {
narrate("bogus ticket", msg_p+5, NULL);
return("FAIL invalid ticket");
}
/* the ticket is valid. release it. */
ticket_array[slot] = TICKET_AVAIL;
num_tickets_out--;
return("THNX see ya!");
}
/*******************************************************************
* do_goodbye
* Tack back ticket client is returning
* IN msg_p message received from client
* Result: ptr to response
* Note: retur is in static buffer over written by each call
*/
char * do_goodbye(char *msg_p) {
int pid,slot; // componse of ticket
/* The user's giving us back a ticket. First we need to get
* the ticket out of the message, which look like:
* GBYE pid.slot
*/
if((sscanf((msg_p + 5),"%d.%d",&pid,&slot) != 2)
|| (ticket_array[slot] != pid)) {
narrate("Bogus ticket",msg_p + 5,NULL);
return "FAIL invalid ticket";
}
// The tickets si valid. Release it
ticket_array[slot] = TICKET_AVAIL;
--num_tickets_out;
// return response
return "THNX See ya!";
} // do_goodbye
