add comments, clean up null pointer references

1 files changed, 78 insertions, 35 deletions

diff --git a/server/main.c b/server/main.c
index c5cea2f..eccbc3d 100644
--- a/server/main.c
+++ b/server/main.c
@@ -19,12 +19,31 @@ static char rcsid_main_c[] = "$Header$";
 #endif SABER
 #endif lint
 static char copyright[] = "Copyright (c) 1987 Massachusetts Institute of Technology.\nPortions Copyright (c) 1986 Student Information Processing Board, Massachusetts Institute of Technology\n";
-static char version[] = "Zephyr Server (Prerelease) 0.1";
+static char version[] = "Zephyr Server (Prerelease) 0.2";
 
 /*
  * Server loop for Zephyr.
  */
 
+/*
+  The Zephyr server maintains several linked lists of information.
+
+  There is an array of servers initialized in main.c and maintained
+  by server_s.c.
+  Each server descriptor contains a pointer to a linked list of hosts
+  which are ``owned'' by that server.
+  Each of these host list entries has an IP address and a pointer to a
+  linked list of clients on that host.
+  Each client has a sockaddr_in, a list of subscriptions, and possibly
+  a session key.
+
+  In addition, the class manager has copies of the pointers to the
+  clients which are registered with a particular class, the
+  not-yet-acknowledged list has copies of pointers to some clients,
+  and the hostm manager may have copies of pointers to some clients
+  (if the client has not acknowledged a packet after a given timeout).
+*/
+
 #include "zserver.h"			/* which includes
 					   zephyr/zephyr.h
 					   	<errno.h>
@@ -56,11 +75,9 @@ static void detach();
 
 int srv_socket;				/* dgram socket for clients
 					   and other servers */
-struct sockaddr_in sock_sin;
-struct in_addr my_addr;
-struct timeval nexthost_tv = {0, 0};	/* time till next host keepalive
-					   initialize to zero so select doesn't
-					   timeout */
+struct sockaddr_in sock_sin;		/* address of the socket */
+struct in_addr my_addr;			/* for convenience, my IP address */
+struct timeval nexthost_tv;		/* time till next timeout for select */
 
 int nservers;				/* number of other servers */
 ZServerDesc_t *otherservers;		/* points to an array of the known
@@ -68,11 +85,10 @@ ZServerDesc_t *otherservers;		/* points to an array of the known
 int me_server_idx;			/* # of my entry in the array */
 ZNotAcked_t *nacklist;			/* list of packets waiting for ack's */
 
-char *programname;			/* set to the last element of argv[0] */
+char *programname;			/* set to the basename of argv[0] */
 char myname[MAXHOSTNAMELEN];		/* my host name */
 
 ZAcl_t zctlacl = { ZEPHYR_CTL_ACL };
-/* These  are commented out until the ACL package does wildcarding. */
 ZAcl_t loginacl = { LOGIN_ACL };
 ZAcl_t locateacl = { LOCATE_ACL };
 ZAcl_t matchallacl = { MATCH_ALL_ACL };
@@ -98,15 +114,17 @@ char **argv;
 	extern char *optarg;
 	extern int optind;
 
+	/* print out various copyright bullshit */
 	puts(version);
 	puts(copyright);
+
 	/* set name */
 	if (programname = rindex(argv[0],'/'))
 		programname++;
 	else programname = argv[0];
 
 #ifdef DEBUG
-	/* open log */
+	/* open log here, before we might send a message */
 	/* XXX eventually make this LOG_DAEMON */
 	openlog(programname, LOG_PID, LOG_LOCAL6);
 #endif DEBUG
@@ -133,10 +151,12 @@ char **argv;
 	/* XXX eventually make this LOG_DAEMON */
 	openlog(programname, LOG_PID, LOG_LOCAL6);
 #endif !DEBUG
+
 	/* set up sockets & my_addr and myname, 
 	   find other servers and set up server table, initialize queues
 	   for retransmits, initialize error tables,
 	   set up restricted classes */
+
 	if (initialize())
 		exit(1);
 
@@ -147,22 +167,26 @@ char **argv;
 
 
 #ifdef DEBUG
-	(void) signal(SIGALRM, bye);
+	/* DBX catches sigterm and does the wrong thing with sigint,
+	   so we provide another hook */
+	(void) signal(SIGALRM, bye);	
+
 	(void) signal(SIGTERM, bye);
 	(void) signal(SIGINT, SIG_IGN);
+	syslog(LOG_INFO, "Ready for action");
 #else
 	(void) signal(SIGINT, bye);
 	(void) signal(SIGTERM, bye);
 #endif DEBUG
-	/* GO! */
-	syslog(LOG_INFO, "Ready for action");
 
+	/* GO! */
 	for EVER {
 		tvp = &nexthost_tv;
 		if (nexttimo != 0L) {
 			nexthost_tv.tv_sec = nexttimo - NOW;
 			nexthost_tv.tv_usec = 0;
-			if (nexthost_tv.tv_sec < 0) { /* timeout has passed! */
+			if (nexthost_tv.tv_sec < 0) {
+				/* timeout has passed! */
 				/* so we process one timeout, then pop to
 				   select, polling for input.  This way we get
 				   work done even if swamped with many
@@ -182,7 +206,7 @@ char **argv;
 			continue;
 		}
 		if (nfound == 0)
-			/* either we timed out for keepalive or we were just
+			/* either we timed out or we were just
 			   polling for input.  Either way we want to continue
 			   the loop, and process the next timeout */
 			continue;
@@ -220,14 +244,12 @@ initialize()
 {
 	register int i;
 	struct in_addr *serv_addr, *hes_addrs;
-	/* XXX temporary hack */
 
 	if (do_net_setup())
 		return(1);
 
 	/* talk to hesiod here, set nservers */
-	if ((hes_addrs = get_server_addrs(&nservers)) ==
-	    (struct in_addr *) NULL) {
+	if (!(hes_addrs = get_server_addrs(&nservers))) {
 		    syslog(LOG_ERR, "No servers?!?");
 		    exit(1);
 	    }
@@ -238,20 +260,24 @@ initialize()
 
 	for (serv_addr = hes_addrs, i = 0; i < nservers; serv_addr++, i++) {
 		setup_server(&otherservers[i], serv_addr);
+		/* is this me? */
 		if (serv_addr->s_addr == my_addr.s_addr) {
 			me_server_idx = i;
 			otherservers[i].zs_state = SERV_UP;
 			timer_reset(otherservers[i].zs_timer);
 			otherservers[i].zs_timer = (timer) NULL;
-			zdbug1("found myself");
+			zdbug((LOG_DEBUG,"found myself"));
 		}
 	}
+
+	/* free up the addresses */
 	xfree(hes_addrs);
+
 	if (me_server_idx == -1) {
 		ZServerDesc_t *temp;
 		syslog(LOG_WARNING, "I'm a renegade server!");
-		temp = (ZServerDesc_t *)realloc((caddr_t) otherservers,(unsigned) (++nservers * sizeof(ZServerDesc_t)));
-		if (temp == NULLZSDT) {
+		temp = (ZServerDesc_t *)realloc((caddr_t) otherservers, (unsigned) (++nservers * sizeof(ZServerDesc_t)));
+		if (!temp) {
 			syslog(LOG_CRIT, "renegade realloc");
 			abort();
 		}
@@ -264,6 +290,7 @@ initialize()
 		   adjusting */
 		for (i = 0; i < nservers - 1; i++) {
 			timer_reset(otherservers[i].zs_timer);
+			/* all the HELLO's are due now */
 			otherservers[i].zs_timer = timer_set_rel(0L, server_timo, (caddr_t) &otherservers[i]);
 		}
 		/* I don't send hello's to myself--cancel the timer */
@@ -272,9 +299,7 @@ initialize()
 
 		me_server_idx = nservers - 1;
 	}
-	if ((nacklist = (ZNotAcked_t *) xmalloc(sizeof(ZNotAcked_t))) ==
-		(ZNotAcked_t *) NULL)
-	{
+	if (!(nacklist = (ZNotAcked_t *) xmalloc(sizeof(ZNotAcked_t)))) {
 		/* unrecoverable */
 		syslog(LOG_CRIT, "nacklist malloc");
 		abort();
@@ -317,7 +342,7 @@ do_net_setup()
 		syslog(LOG_ERR, "no hostname: %m");
 		return(1);
 	}
-	if ((hp = gethostbyname(hostname)) == (struct hostent *) NULL) {
+	if (!(hp = gethostbyname(hostname))) {
 		syslog(LOG_ERR, "no gethostbyname repsonse");
 		(void) strncpy(myname, hostname, MAXHOSTNAMELEN);
 		return(1);
@@ -325,12 +350,9 @@ do_net_setup()
 	(void) strncpy(myname, hp->h_name, MAXHOSTNAMELEN);
 	bcopy((caddr_t) hp->h_addr, (caddr_t) &my_addr, sizeof(hp->h_addr));
 	
-	/* note that getservbyname may actually ask hesiod and not
-	   /etc/services */
 	(void) setservent(1);		/* keep file/connection open */
 	
-	if ((sp = getservbyname("zephyr-clt", "udp")) ==
-	    (struct servent *) NULL) {
+	if (!(sp = getservbyname("zephyr-clt", "udp"))) {
 		syslog(LOG_ERR, "zephyr-clt/udp unknown");
 		return(1);
 	}
@@ -356,9 +378,11 @@ do_net_setup()
 }    
 
 
-/* get a list of server addresses, from Hesiod.  Return a pointer to an
-   array of allocated storage.  This storage is freed by the caller.
-   */
+/*
+ * get a list of server addresses, from Hesiod.  Return a pointer to an
+ * array of allocated storage.  This storage is freed by the caller.
+ */
+
 static struct in_addr *
 get_server_addrs(number)
 int *number;				/* RETURN */
@@ -372,7 +396,7 @@ int *number;				/* RETURN */
 	register struct hostent *hp;
 
 	/* get the names from Hesiod */
-	if ((server_hosts = hes_resolve("zephyr","sloc")) == (char **)NULL)
+	if (!(server_hosts = hes_resolve("zephyr","sloc")))
 		return((struct in_addr *)NULL);
 
 	/* count up */
@@ -384,7 +408,9 @@ int *number;				/* RETURN */
 	for (cpp = server_hosts, addr = addrs, i = 0; *cpp; cpp++) {
 		hp = gethostbyname(*cpp);
 		if (hp) {
-			bcopy((caddr_t)hp->h_addr, (caddr_t) addr, sizeof(struct in_addr));
+			bcopy((caddr_t)hp->h_addr,
+			      (caddr_t) addr,
+			      sizeof(struct in_addr));
 			addr++, i++;
 		} else
 			syslog(LOG_WARNING, "hostname failed, %s",*cpp);
@@ -393,6 +419,11 @@ int *number;				/* RETURN */
 	return(addrs);
 }
 
+/*
+ * initialize the server structure for address addr, and set a timer
+ * to go off immediately to send hello's to other servers.
+ */
+
 static void
 setup_server(server, addr)
 register ZServerDesc_t *server;
@@ -411,8 +442,7 @@ struct in_addr *addr;
 
 	/* set up a timer for this server */
 	server->zs_timer = timer_set_rel(0L, server_timo, (caddr_t) server);
-	if ((host = (ZHostList_t *) xmalloc(sizeof(ZHostList_t))) == NULLZHLT)
-	{
+	if (!(host = (ZHostList_t *) xmalloc(sizeof(ZHostList_t)))) {
 		/* unrecoverable */
 		syslog(LOG_CRIT, "zs_host malloc");
 		abort();
@@ -422,6 +452,10 @@ struct in_addr *addr;
 	return;
 }
 
+/*
+ * print out a usage message.
+ */
+
 static void
 usage()
 {
@@ -433,6 +467,10 @@ usage()
 	exit(2);
 }
 
+/*
+ * interrupt routine
+ */
+
 static int
 bye()
 {
@@ -441,7 +479,12 @@ bye()
 	exit(0);
 	/*NOTREACHED*/
 }
+
 #ifndef DEBUG
+/*
+ * detach from the terminal
+ */
+
 static void
 detach()
 {