added support for server going dormant

[moira.git] / server / mr_main.c

/*
 *	$Source$
 *	$Author$
 *	$Header$
 *
 *	Copyright (C) 1987 by the Massachusetts Institute of Technology
 *	For copying and distribution information, please see the file
 *	<mit-copyright.h>.
 *
 * 	SMS server process.
 *
 * 	Most of this is stolen from ../gdb/tsr.c
 *
 * 	You are in a maze of twisty little finite automata, all different.
 * 	Let the reader beware.
 * 
 */

static char *rcsid_sms_main_c = "$Header$";

#include <mit-copyright.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/signal.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include "sms_server.h"
#include <krb_et.h>

extern CONNECTION newconn, listencon;

extern int nclients;
extern client **clients, *cur_client;

extern OPERATION listenop;
extern LIST_OF_OPERATIONS op_list;

extern struct sockaddr_in client_addr;
extern int client_addrlen;
extern TUPLE client_tuple;

extern char *whoami;
extern char buf1[BUFSIZ];
extern char *takedown;
extern int errno;
extern FILE *journal;
#define JOURNAL "/u1/sms/journal"

extern char *malloc();
extern int free();
extern char *inet_ntoa();
extern void sms_com_err();
extern void do_client();

extern int sigshut();
void clist_append();
void oplist_append();
void reapchild(), godormant(), gowakeup();

extern time_t now;

/*
 * Main SMS server loop.
 *
 * Initialize the world, then start accepting connections and
 * making progress on current connections.
 */

/*ARGSUSED*/
int
main(argc, argv)
	int argc;
	char **argv;
{
	int status;
	time_t tardy;
	struct stat stbuf;
	
	whoami = argv[0];
	/*
	 * Error handler init.
	 */
	initialize_sms_error_table();
	initialize_krb_error_table();
	set_com_err_hook(sms_com_err);
	setlinebuf(stderr);
	
	if (argc != 1) {
		com_err(whoami, 0, "Usage: smsd");
		exit(1);
	}		

	/* Profiling implies that getting rid of one level of call
	 * indirection here wins us maybe 1% on the VAX.
	 */
	gdb_amv = malloc;
	gdb_fmv = free;
	
	/*
	 * GDB initialization.
	 */
	if(gdb_init() != 0) {
		com_err(whoami, 0, "GDB initialization failed.");
		exit(1);
	}
	gdb_debug(0); /* this can be patched, if necessary, to enable */
		      /* GDB level debugging .. */
	krb_realm = malloc(REALM_SZ);
	get_krbrlm(krb_realm, 1);
	
	/*
	 * Database initialization.
	 */

	if ((status = sms_open_database()) != 0) {
		com_err(whoami, status, " when trying to open database.");
		exit(1);
	}
	
	sanity_check_queries();
	sanity_check_database();

	/*
	 * Set up client array handler.
	 */
	nclients = 0;
	clients = (client **) malloc(0);
	
	/*
	 * Signal handlers
	 *	There should probably be a few more of these. This is
	 *	duplicated on the next page, be sure to also add any
	 *	additional handlers there.
	 */
	
	if ((((int)signal (SIGTERM, sigshut)) < 0) ||
	    (((int)signal (SIGCHLD, reapchild)) < 0) ||
	    (((int)signal (SIGUSR1, godormant)) < 0) ||
	    (((int)signal (SIGUSR2, gowakeup)) < 0) ||
	    (((int)signal (SIGHUP, sigshut)) < 0)) {
		com_err(whoami, errno, " Unable to establish signal handlers.");
		exit(1);
	}
	
	journal = fopen(JOURNAL, "a");
	if (journal == NULL) {
	    com_err(whoami, errno, " while opening journal file");
	    exit(1);
	}

	/*
	 * Establish template connection.
	 */
	if ((status = do_listen()) != 0) {
		com_err(whoami, status,
			" while trying to create listening connection");
		exit(1);
	}
	
	op_list = create_list_of_operations(1, listenop);
	
	com_err(whoami, 0, "started (pid %d)", getpid());
	com_err(whoami, 0, rcsid_sms_main_c);
	send_zgram("SMS", "server started");

	/*
	 * Run until shut down.
	 */
	while(!takedown) {		
		register int i;
		/*
		 * Block until something happens.
		 */
#ifdef notdef
		com_err(whoami, 0, "tick");
#endif notdef
		if (dormant == SLEEPY) {
		    sms_close_database();
		    com_err(whoami, 0, "database closed");
		    send_zgram("SMS", "database closed");
		    dormant = ASLEEP;
		} else if (dormant == GROGGY) {
		    sms_open_database();
		    com_err(whoami, 0, "database open");
		    if ((((int)signal (SIGTERM, sigshut)) < 0) ||
			(((int)signal (SIGCHLD, reapchild)) < 0) ||
			(((int)signal (SIGUSR1, godormant)) < 0) ||
			(((int)signal (SIGUSR2, gowakeup)) < 0) ||
			(((int)signal (SIGHUP, sigshut)) < 0)) {
			com_err(whoami, errno,
				" Unable to reestablish signal handlers.");
			exit(1);
		    }
		    send_zgram("SMS", "database open again");
		    dormant = AWAKE;
		}

		errno = 0;
		status = op_select_any(op_list, 0,
				       (fd_set *)NULL, (fd_set *)NULL,
				       (fd_set *)NULL, (struct timeval *)NULL);

		if (status == -1) {
		    	com_err(whoami, errno, " error from op_select");
			continue;
		} else if (status != -2) {
			com_err(whoami, 0, " wrong return from op_select_any");
			continue;
		}
		if (takedown) break;
		time(&now);
#ifdef notdef
		fprintf(stderr, "    tick\n");
#endif notdef
		/*
		 * Handle any new connections; this comes first so
		 * errno isn't tromped on.
		 */
		if (OP_DONE(listenop)) {
			if (OP_STATUS(listenop) == OP_CANCELLED) {
				if (errno == EWOULDBLOCK) {
					do_reset_listen();
				} else {
					com_err(whoami, errno,
						" error on listen");
					exit(1);
				}
			} else if ((status = new_connection()) != 0) {
				com_err(whoami, errno,
					" Error on listening operation.");
				/*
				 * Sleep here to prevent hosing?
				 */
			}
			/* if the new connection is our only connection,
			 * and the server is supposed to be down, then go
			 * down now.
			 */
			if ((dormant == AWAKE) && (nclients == 1) &&
			    (stat(SMS_MOTD_FILE, &stbuf) == 0)) {
			    com_err(whoami, 0, "motd file exists, slumbertime");
			    dormant = SLEEPY;
			}
			/* on new connection, if we are no longer supposed
			 * to be down, then wake up.
			 */
			if ((dormant == ASLEEP) &&
			    (stat(SMS_MOTD_FILE, &stbuf) == -1) &&
			    (errno == ENOENT)) {
			    com_err(whoami, 0, "motd file no longer exists, waking up");
			    dormant = GROGGY;
			}
			  
		}
		/*
		 * Handle any existing connections.
		 */
		tardy = now - 30*60;
		
		for (i=0; i<nclients; i++) {
			cur_client = clients[i];
			if (OP_DONE(clients[i]->pending_op)) {
				cur_client->last_time_used = now;
				do_client(cur_client);
			} else if (clients[i]->last_time_used < tardy) {
				com_err(whoami, 0, "Shutting down connection due to inactivity");
				shutdown(cur_client->con->in.fd, 0);
			}
			cur_client = NULL;
			if (takedown) break;
		}
	}
	com_err(whoami, 0, "%s", takedown);
	sms_close_database();
	send_zgram("SMS", takedown);
	return 0;
}

/*
 * Set up the template connection and queue the first accept.
 */

int
do_listen()
{
	char *service = index(SMS_GDB_SERV, ':') + 1;

	listencon = create_listening_connection(service);

	if (listencon == NULL)
		return errno;

	listenop = create_operation();
	client_addrlen = sizeof(client_addr);

	start_accepting_client(listencon, listenop, &newconn,
			       (char *)&client_addr,
			       &client_addrlen, &client_tuple);
	return 0;
}


do_reset_listen()
{
	client_addrlen = sizeof(client_addr);
	start_accepting_client(listencon, listenop, &newconn,
			       (char *)&client_addr,
			       &client_addrlen, &client_tuple);
}

/*
 * This routine is called when a new connection comes in.
 *
 * It sets up a new client and adds it to the list of currently active clients.
 */
int
new_connection()
{
	register client *cp;
	static counter = 0;
	
	/*
	 * Make sure there's been no error
	 */
	if(OP_STATUS(listenop) != OP_COMPLETE) {
		return errno;
	}
	
	if (newconn == NULL) {
		return SMS_NOT_CONNECTED;
	}

	/*
	 * Set up the new connection and reply to the client
	 */
	cp = (client *)malloc(sizeof *cp);
	bzero(cp, sizeof(*cp));
	cp->action = CL_ACCEPT;
	cp->con = newconn;
	cp->id = counter++;
	cp->args = NULL;
	cp->clname = NULL;
	cp->reply.sms_argv = NULL;
	cp->first = NULL;
	cp->last = NULL;
	cp->last_time_used = now;
	newconn = NULL;
	
	cp->pending_op = create_operation();
	reset_operation(cp->pending_op);
	oplist_append(&op_list, cp->pending_op);
	cur_client = cp;
	
	/*
	 * Add a new client to the array..
	 */
	clist_append(cp);
	
	/*
	 * Let him know we heard him.
	 */
	start_replying_to_client(cp->pending_op, cp->con, GDB_ACCEPTED,
				 "", "");

	cp->haddr = client_addr;
	
	/*
	 * Log new connection.
	 */
	
	com_err(whoami, 0, "New connection from %s port %d (now %d client%s)",
		inet_ntoa(cp->haddr.sin_addr),
		(int)ntohs(cp->haddr.sin_port),
		nclients,
		nclients!=1?"s":"");
	
	/*
	 * Get ready to accept the next connection.
	 */
	reset_operation(listenop);
	client_addrlen = sizeof(client_addr);

	start_accepting_client(listencon, listenop, &newconn,
			       (char *)&client_addr,
			       &client_addrlen, &client_tuple);
	return 0;
}

/*
 * Add a new client to the known clients.
 */
void
clist_append(cp)
	client *cp;
{		
	client **clients_n;
	
	nclients++;
	clients_n = (client **)malloc
		((unsigned)(nclients * sizeof(client *)));
	bcopy((char *)clients, (char *)clients_n, (nclients-1)*sizeof(cp));
	clients_n[nclients-1] = cp;
	free((char *)clients);
	clients = clients_n;
	clients_n = NULL;
}

		
void
clist_delete(cp)
	client *cp;
{
	client **clients_n, **scpp, **dcpp; /* source and dest client */
					    /* ptr ptr */
	
	int found_it = 0;
	
	clients_n = (client **)malloc
		((unsigned)((nclients - 1)* sizeof(client *)));
	for (scpp = clients, dcpp = clients_n; scpp < clients+nclients; ) {
		if (*scpp != cp) {
			*dcpp++ = *scpp++;
		} else {
			scpp++;
			if (found_it) abort();
			found_it = 1;
		}			
	}
	--nclients;	
	free((char *)clients);
	clients = clients_n;
	clients_n = NULL;
	oplist_delete(op_list, cp->pending_op);
	reset_operation(cp->pending_op);
	delete_operation(cp->pending_op);
	sever_connection(cp->con);
	free((char *)cp);
}

/*
 * Add a new operation to a list of operations.
 *
 * This should be rewritten to use realloc instead, since in most
 * cases it won't have to copy the array.
 */

void
oplist_append(oplp, op)
	LIST_OF_OPERATIONS *oplp;
	OPERATION op;
{
	int count = (*oplp)->count+1;
	LIST_OF_OPERATIONS newlist = (LIST_OF_OPERATIONS)
		db_alloc(size_of_list_of_operations(count));
	bcopy((char *)(*oplp), (char *)newlist,
	      size_of_list_of_operations((*oplp)->count));
	newlist->count++;
	newlist->op[count-1] = op;
	db_free((char *)(*oplp), size_of_list_of_operations(count-1));
	(*oplp) = newlist;
}


oplist_delete(oplp, op)
	LIST_OF_OPERATIONS oplp;
	register OPERATION op;
{
	register OPERATION *s;
	register int c;
	
	for (s = oplp->op, c=oplp->count; c; --c, ++s) {
		if (*s == op) {
			while (c > 0) {
				*s = *(s+1);
				++s;
				--c;
			}
			oplp->count--;
			return;
		}
	}
	abort();
}


void reapchild()
{
    union wait status;
    int pid;

    if (takedown || dormant == ASLEEP)
      return;
    while ((pid = wait3(&status, WNOHANG, (struct rusage *)0)) > 0) {
	if  (status.w_termsig == 0 && status.w_retcode == 0)
	  com_err(whoami, 0, "child exited successfully");
	else
	  com_err(whoami, 0, "%d: child exits with signal %d status %d",
		  pid, status.w_termsig, status.w_retcode);
    }
}


void godormant()
{
    switch (dormant) {
    case AWAKE:
    case GROGGY:
	com_err(whoami, 0, "requested to go dormant");
	break;
    case ASLEEP:
	com_err(whoami, 0, "already asleep");
	break;
    case SLEEPY:
	break;
    }
    dormant = SLEEPY;
}


void gowakeup()
{
    switch (dormant) {
    case ASLEEP:
    case SLEEPY:
	com_err(whoami, 0, "Good morning");
	break;
    case AWAKE:
	com_err(whoami, 0, "already awake");
	break;
    case GROGGY:
	break;
    }
    dormant = GROGGY;
}