X-Git-Url: https://code.citadel.org/?a=blobdiff_plain;f=citadel%2Fsysdep.c;h=655bb7249286fc26975c3acd563f76b0dbb5e663;hb=fe4a9ff9d1b33197fb5dfc45567b98c63049d7b6;hp=18e66b9f3c1cfb6b94cd703d93323701f41c1adf;hpb=9120a1b98dcb0d551b94d01b3353f24b53573491;p=citadel.git

diff --git a/citadel/sysdep.c b/citadel/sysdep.c
index 18e66b9f3..655bb7249 100644
--- a/citadel/sysdep.c
+++ b/citadel/sysdep.c
@@ -1,16 +1,15 @@
 /*
+ * $Id$
+ *
  * Citadel/UX "system dependent" stuff.
  * See copyright.txt for copyright information.
  *
- * $Id$
- *
- * Here's where we (hopefully) have all the parts of the Citadel server that
+ * Here's where we (hopefully) have most parts of the Citadel server that
  * would need to be altered to run the server in a non-POSIX environment.
- * Wherever possible, we use function wrappers and type definitions to create
- * abstractions that are platform-independent from the calling side.
  * 
- * Eventually we'll try porting to a different platform and either have
- * multiple variants of this file or simply load it up with #ifdefs.
+ * If we ever port to a different platform and either have multiple
+ * variants of this file or simply load it up with #ifdefs.
+ *
  */
 
 
@@ -22,18 +21,23 @@
 #include <ctype.h>
 #include <signal.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/wait.h>
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <limits.h>
 #include <netinet/in.h>
 #include <netdb.h>
+#include <sys/un.h>
 #include <string.h>
 #include <pwd.h>
 #include <errno.h>
 #include <stdarg.h>
 #include <syslog.h>
 #include <grp.h>
+#ifdef __GNUC__
+#include <malloc.h>
+#endif
 #ifdef HAVE_PTHREAD_H
 #include <pthread.h>
 #endif
@@ -63,30 +67,56 @@ struct TheHeap *heap = NULL;
 pthread_mutex_t Critters[MAX_SEMAPHORES];	/* Things needing locking */
 pthread_key_t MyConKey;				/* TSD key for MyContext() */
 
-int msock;					/* master listening socket */
-int verbosity = 3;				/* Logging level */
+int verbosity = DEFAULT_VERBOSITY;		/* Logging level */
 
 struct CitContext masterCC;
+int rescan[2];					/* The Rescan Pipe */
+time_t last_purge = 0;				/* Last dead session purge */
+static int num_threads = 0;			/* Current number of threads */
+int num_sessions = 0;				/* Current number of sessions */
+
+fd_set masterfds;				/* Master sockets etc. */
+int masterhighest;
+
+time_t last_timer = 0L;				/* Last timer hook processing */
+
+static pthread_t initial_thread;		/* tid for main() thread */
 
 
 /*
  * lprintf()  ...   Write logging information
+ * 
+ * Note: the variable "buf" below needs to be large enough to handle any
+ * log data sent through this function.  BE CAREFUL!
  */
 void lprintf(int loglevel, const char *format, ...) {   
         va_list arg_ptr;
-	char buf[512];
+	char buf[4096];
   
         va_start(arg_ptr, format);   
         vsprintf(buf, format, arg_ptr);   
         va_end(arg_ptr);   
 
 	if (loglevel <= verbosity) { 
-		fprintf(stderr, "%s", buf);
+		struct timeval tv;
+		struct tm *tim;
+
+		gettimeofday(&tv, NULL);
+		tim = localtime(&(tv.tv_sec));
+		/*
+		 * Log provides millisecond accuracy.  If you need
+		 * microsecond accuracy and your OS supports it, change
+		 * %03ld to %06ld and remove " / 1000" after tv.tv_usec.
+		 */
+		fprintf(stderr, "%04d/%02d/%02d %2d:%02d:%02d.%03ld %s",
+			tim->tm_year + 1900, tim->tm_mon + 1, tim->tm_mday,
+			tim->tm_hour, tim->tm_min, tim->tm_sec,
+			tv.tv_usec / 1000, buf);
 		fflush(stderr);
-		}
+	}
 
 	PerformLogHooks(loglevel, buf);
-	}   
+}   
 
 
 
@@ -96,7 +126,11 @@ void *tracked_malloc(size_t tsize, char *tfile, int tline) {
 	struct TheHeap *hptr;
 
 	ptr = malloc(tsize);
-	if (ptr == NULL) return(NULL);
+	if (ptr == NULL) {
+		lprintf(3, "DANGER!  mallok(%d) at %s:%d failed!\n",
+			tsize, tfile, tline);
+		return(NULL);
+	}
 
 	hptr = (struct TheHeap *) malloc(sizeof(struct TheHeap));
 	strcpy(hptr->h_file, tfile);
@@ -105,8 +139,17 @@ void *tracked_malloc(size_t tsize, char *tfile, int tline) {
 	hptr->h_ptr = ptr;
 	heap = hptr;
 	return ptr;
-	}
+}
+
+char *tracked_strdup(const char *orig, char *tfile, int tline) {
+	char *s;
 
+	s = tracked_malloc( (strlen(orig)+1), tfile, tline);
+	if (s == NULL) return NULL;
+
+	strcpy(s, orig);
+	return s;
+}
 
 void tracked_free(void *ptr) {
 	struct TheHeap *hptr, *freeme;
@@ -115,19 +158,19 @@ void tracked_free(void *ptr) {
 		hptr = heap->next;
 		free(heap);
 		heap = hptr;
-		}
+	}
 	else {
 		for (hptr=heap; hptr->next!=NULL; hptr=hptr->next) {
 			if (hptr->next->h_ptr == ptr) {
 				freeme = hptr->next;
 				hptr->next = hptr->next->next;
 				free(freeme);
-				}
 			}
 		}
+	}
 
 	free(ptr);
-	}
+}
 
 void *tracked_realloc(void *ptr, size_t size) {
 	void *newptr;
@@ -137,10 +180,10 @@ void *tracked_realloc(void *ptr, size_t size) {
 
 	for (hptr=heap; hptr!=NULL; hptr=hptr->next) {
 		if (hptr->h_ptr == ptr) hptr->h_ptr = newptr;
-		}
+	}
 
 	return newptr;
-	}
+}
 
 
 void dump_tracked() {
@@ -150,26 +193,18 @@ void dump_tracked() {
 	for (hptr=heap; hptr!=NULL; hptr=hptr->next) {
 		cprintf("%20s %5d\n",
 			hptr->h_file, hptr->h_line);
-		}
-	cprintf("000\n");
 	}
+#ifdef __GNUC__
+        malloc_stats();
 #endif
 
-#ifndef HAVE_PTHREAD_CANCEL
-/*
- * signal handler to fake thread cancellation; only required on BSDI as far
- * as I know.
- */
-
-static pthread_t main_thread_id;
-
-static RETSIGTYPE cancel_thread(int signum) {
-	pthread_exit(NULL);
-	}
+	cprintf("000\n");
+}
 #endif
 
+
 /*
- * we used to use master_cleanup() as a signal handler to shut down the server.
+ * We used to use master_cleanup() as a signal handler to shut down the server.
  * however, master_cleanup() and the functions it calls do some things that
  * aren't such a good idea to do from a signal handler: acquiring mutexes,
  * playing with signal masks on BSDI systems, etc. so instead we install the
@@ -177,11 +212,11 @@ static RETSIGTYPE cancel_thread(int signum) {
  * that it's time to call master_cleanup() and exit.
  */
 
-static volatile int time_to_die = 0;
+volatile int time_to_die = 0;
 
 static RETSIGTYPE signal_cleanup(int signum) {
 	time_to_die = 1;
-	}
+}
 
 
 /*
@@ -193,16 +228,17 @@ void init_sysdep(void) {
 	/* Set up a bunch of semaphores to be used for critical sections */
 	for (a=0; a<MAX_SEMAPHORES; ++a) {
 		pthread_mutex_init(&Critters[a], NULL);
-		}
+	}
 
 	/*
 	 * Set up a place to put thread-specific data.
 	 * We only need a single pointer per thread - it points to the
-	 * thread's CitContext structure in the ContextList linked list.
+	 * CitContext structure (in the ContextList linked list) of the
+	 * session to which the calling thread is currently bound.
 	 */
 	if (pthread_key_create(&MyConKey, NULL) != 0) {
 		lprintf(1, "Can't create TSD key!!  %s\n", strerror(errno));
-		}
+	}
 
 	/*
 	 * The action for unexpected signals and exceptions should be to
@@ -212,12 +248,14 @@ void init_sysdep(void) {
 	signal(SIGQUIT, signal_cleanup);
 	signal(SIGHUP, signal_cleanup);
 	signal(SIGTERM, signal_cleanup);
+
+	/*
+	 * Do not shut down the server on broken pipe signals, otherwise the
+	 * whole Citadel service would come down whenever a single client
+	 * socket breaks.
+	 */
 	signal(SIGPIPE, SIG_IGN);
-#ifndef HAVE_PTHREAD_CANCEL /* fake it - only BSDI afaik */
-	main_thread_id = pthread_self();
-	signal(SIGUSR1, cancel_thread);
-#endif
-	}
+}
 
 
 /*
@@ -225,254 +263,180 @@ void init_sysdep(void) {
  */
 void begin_critical_section(int which_one)
 {
-#ifdef HAVE_PTHREAD_CANCEL
-	int oldval;
-#else
-	sigset_t set;
-#endif
-
-	/* lprintf(8, "begin_critical_section(%d)\n", which_one); */
-
-#ifdef HAVE_PTHREAD_CANCEL
-	/* Don't get interrupted during the critical section */
-	pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, &oldval);
-#else
-	/* We're faking cancellation with signals. Block SIGUSR1 while we're in
-	 * the critical section. */
-	if (!pthread_equal(pthread_self(), main_thread_id)) {
-		sigemptyset(&set);
-		sigaddset(&set, SIGUSR1);
-		pthread_sigmask(SIG_BLOCK, &set, NULL);
-		}
-#endif
-
-	/* Obtain a semaphore */
+	/* lprintf(9, "begin_critical_section(%d)\n", which_one); */
+	/* ensure nobody ever tries to do a critical section within a
+	   transaction; this could lead to deadlock. */
+	cdb_check_handles();
 	pthread_mutex_lock(&Critters[which_one]);
-
-	}
+}
 
 /*
  * Release a semaphore lock to end a critical section.
  */
 void end_critical_section(int which_one)
 {
-#ifdef HAVE_PTHREAD_CANCEL
-	int oldval;
-#else
-	sigset_t set;
-#endif
-
-	/* lprintf(8, "  end_critical_section(%d)\n", which_one); */
-
-	/* Let go of the semaphore */
+	/* lprintf(9, "end_critical_section(%d)\n", which_one); */
 	pthread_mutex_unlock(&Critters[which_one]);
-
-#ifdef HAVE_PTHREAD_CANCEL
-	/* If a cancel was sent during the critical section, do it now.
-	 * Then re-enable thread cancellation.
-	 */
-	pthread_testcancel();
-	pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldval);
-	pthread_testcancel();
-#else
-	/* We're faking it. Unblock SIGUSR1; signals sent during the critical
-	 * section should now be able to kill us. */
-	if (!pthread_equal(pthread_self(), main_thread_id)) {
-		sigemptyset(&set);
-		sigaddset(&set, SIGUSR1);
-		pthread_sigmask(SIG_UNBLOCK, &set, NULL);
-		}
-#endif
-
-	}
+}
 
 
 
 /*
  * This is a generic function to set up a master socket for listening on
  * a TCP port.  The server shuts down if the bind fails.
+ *
  */
 int ig_tcp_server(int port_number, int queue_len)
 {
 	struct sockaddr_in sin;
 	int s, i;
+	int actual_queue_len;
+
+	actual_queue_len = queue_len;
+	if (actual_queue_len < 5) actual_queue_len = 5;
 
 	memset(&sin, 0, sizeof(sin));
 	sin.sin_family = AF_INET;
 	sin.sin_addr.s_addr = INADDR_ANY;
-
-	if (port_number == 0) {
-		lprintf(1,
-			"citserver: No port number specified.  Run setup.\n");
-		exit(1);
-		}
-	
 	sin.sin_port = htons((u_short)port_number);
 
-	s = socket(PF_INET, SOCK_STREAM, (getprotobyname("tcp")->p_proto));
+	s = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+
 	if (s < 0) {
 		lprintf(1, "citserver: Can't create a socket: %s\n",
 			strerror(errno));
-		exit(errno);
-		}
+		return(-1);
+	}
 
-	/* Set the SO_REUSEADDR socket option, because it makes sense. */
 	i = 1;
 	setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i));
 
 	if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
-		lprintf(1, "citserver: Can't bind: %s\n", strerror(errno));
-		exit(errno);
-		}
+		lprintf(1, "citserver: Can't bind: %s\n",
+			strerror(errno));
+		close(s);
+		return(-1);
+	}
 
-	if (listen(s, queue_len) < 0) {
+	if (listen(s, actual_queue_len) < 0) {
 		lprintf(1, "citserver: Can't listen: %s\n", strerror(errno));
-		exit(errno);
-		}
+		close(s);
+		return(-1);
+	}
 
 	return(s);
-	}
+}
+
 
 
 /*
- * Return a pointer to a thread's own CitContext structure (old)
- * NOTE: this version of MyContext() is commented out because it is no longer
- * in use.  It was written before I discovered TSD keys.  This
- * version pounds through the context list until it finds the one matching
- * the currently running thread.  It remains here, commented out, in case it
- * is needed for future ports to threading libraries which have the equivalent
- * of pthread_self() but not pthread_key_create() and its ilk.
- *
- * struct CitContext *MyContext() {
- *	struct CitContext *ptr;
- *	THREAD me;
- *
- *	me = pthread_self();
- *	for (ptr=ContextList; ptr!=NULL; ptr=ptr->next) {
- *		if (ptr->mythread == me) return(ptr);
- *		}
- *	return(NULL);
- *	}
+ * Create a Unix domain socket and listen on it
  */
+int ig_uds_server(char *sockpath, int queue_len)
+{
+	struct sockaddr_un addr;
+	int s;
+	int i;
+	int actual_queue_len;
+
+	actual_queue_len = queue_len;
+	if (actual_queue_len < 5) actual_queue_len = 5;
+
+	i = unlink(sockpath);
+	if (i != 0) if (errno != ENOENT) {
+		lprintf(1, "citserver: can't unlink %s: %s\n",
+			sockpath, strerror(errno));
+		return(-1);
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sun_family = AF_UNIX;
+	safestrncpy(addr.sun_path, sockpath, sizeof addr.sun_path);
+
+	s = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (s < 0) {
+		lprintf(1, "citserver: Can't create a socket: %s\n",
+			strerror(errno));
+		return(-1);
+	}
+
+	if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+		lprintf(1, "citserver: Can't bind: %s\n",
+			strerror(errno));
+		return(-1);
+	}
+
+	if (listen(s, actual_queue_len) < 0) {
+		lprintf(1, "citserver: Can't listen: %s\n", strerror(errno));
+		return(-1);
+	}
+
+	chmod(sockpath, 0777);
+	return(s);
+}
+
+
 
 /*
- * Return a pointer to a thread's own CitContext structure (new)
+ * Return a pointer to the CitContext structure bound to the thread which
+ * called this function.  If there's no such binding (for example, if it's
+ * called by the housekeeper thread) then a generic 'master' CC is returned.
  */
 struct CitContext *MyContext(void) {
 	struct CitContext *retCC;
 	retCC = (struct CitContext *) pthread_getspecific(MyConKey);
 	if (retCC == NULL) retCC = &masterCC;
 	return(retCC);
-	}
+}
 
 
 /*
- * Wedge our way into the context list.
+ * Initialize a new context and place it in the list.  The session number
+ * used to be the PID (which is why it's called cs_pid), but that was when we
+ * had one process per session.  Now we just assign them sequentially, starting
+ * at 1 (don't change it to 0 because masterCC uses 0) and re-using them when
+ * sessions terminate.
  */
 struct CitContext *CreateNewContext(void) {
-	struct CitContext *me;
+	struct CitContext *me, *ptr;
+	int num = 1;
+	int startover = 0;
 
-	lprintf(9, "CreateNewContext: calling malloc()\n");
 	me = (struct CitContext *) mallok(sizeof(struct CitContext));
 	if (me == NULL) {
 		lprintf(1, "citserver: can't allocate memory!!\n");
-		pthread_exit(NULL);
-		}
-	memset(me, 0, sizeof(struct CitContext));
-
-	begin_critical_section(S_SESSION_TABLE);
-	me->next = ContextList;
-	ContextList = me;
-	end_critical_section(S_SESSION_TABLE);
-	return(me);
-	}
-
-/*
- * Add a thread's thread ID to the context
- */
-void InitMyContext(struct CitContext *con)
-{
-#ifdef HAVE_PTHREAD_CANCEL
-	int oldval;
-#endif
-
-	con->mythread = pthread_self();
-#ifdef HAVE_PTHREAD_CANCEL
-	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldval);
-	pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldval);
-#endif
-	if (pthread_setspecific(MyConKey, (void *)con) != 0) {
-		lprintf(1, "ERROR!  pthread_setspecific() failed: %s\n",
-			strerror(errno));
-		}
+		return NULL;
 	}
+	memset(me, 0, sizeof(struct CitContext));
 
-/*
- * Remove a context from the context list.
- */
-void RemoveContext(struct CitContext *con)
-{
-	struct CitContext *ptr;
-
-	lprintf(7, "Starting RemoveContext()\n");
-	lprintf(9, "Session count before RemoveContext is %d\n",
-		session_count());
-	if (con==NULL) {
-		lprintf(7, "WARNING: RemoveContext() called with null!\n");
-		return;
-		}
-
-	/*
-	 * session_count() starts its own S_SESSION_TABLE critical section;
-	 * so do not call it from within this loop.
+	/* The new context will be created already in the CON_EXECUTING state
+	 * in order to prevent another thread from grabbing it while it's
+	 * being set up.
 	 */
+	me->state = CON_EXECUTING;
+
 	begin_critical_section(S_SESSION_TABLE);
-	lprintf(7, "Closing socket %d\n", con->client_socket);
-	close(con->client_socket);
 
-	lprintf(9, "Dereferencing session context\n");
-	if (ContextList==con) {
-		ContextList = ContextList->next;
-		}
-	else {
+	/* obtain a unique session number */
+	do {
+		startover = 0;
 		for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
-			if (ptr->next == con) {
-				ptr->next = con->next;
-				}
+			if (ptr->cs_pid == num) {
+				++num;
+				startover = 1;
 			}
 		}
+	} while (startover == 1);
 
-	lprintf(9, "Freeing session context...\n");	
-	phree(con);
-	lprintf(9, "...done.\n");
-	end_critical_section(S_SESSION_TABLE);
-
-	lprintf(9, "Session count after RemoveContext is %d\n",
-		session_count());
-
-	lprintf(7, "Done with RemoveContext\n");
-	}
-
-
-/*
- * Return the number of sessions currently running.
- * (This should probably be moved out of sysdep.c)
- */
-int session_count(void) {
-	struct CitContext *ptr;
-	int TheCount = 0;
+	me->cs_pid = num;
+	me->next = ContextList;
+	ContextList = me;
+	++num_sessions;
 
-	lprintf(9, "session_count() starting\n");
-	begin_critical_section(S_SESSION_TABLE);
-	for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
-		++TheCount;
-		lprintf(9, "Counted session %3d (%d)\n", ptr->cs_pid, TheCount);
-		}
 	end_critical_section(S_SESSION_TABLE);
+	return(me);
+}
 
-	lprintf(9, "session_count() finishing\n");
-	return(TheCount);
-	}
 
 
 /*
@@ -482,17 +446,33 @@ void client_write(char *buf, int nbytes)
 {
 	int bytes_written = 0;
 	int retval;
+	int sock;
+
+
+	if (CC->redirect_fp != NULL) {
+		fwrite(buf, nbytes, 1, CC->redirect_fp);
+		return;
+	}
+
+	if (CC->redirect_sock > 0) {
+		sock = CC->redirect_sock;	/* and continue below... */
+	}
+	else {
+		sock = CC->client_socket;
+	}
+
 	while (bytes_written < nbytes) {
-		retval = write(CC->client_socket, &buf[bytes_written],
+		retval = write(sock, &buf[bytes_written],
 			nbytes - bytes_written);
 		if (retval < 1) {
 			lprintf(2, "client_write() failed: %s\n",
 				strerror(errno));
-			cleanup(errno);
-			}
-		bytes_written = bytes_written + retval;
+			if (sock == CC->client_socket) CC->kill_me = 1;
+			return;
 		}
+		bytes_written = bytes_written + retval;
 	}
+}
 
 
 /*
@@ -502,14 +482,14 @@ void client_write(char *buf, int nbytes)
  */
 void cprintf(const char *format, ...) {   
         va_list arg_ptr;   
-        char buf[256];   
+        char buf[SIZ];   
    
         va_start(arg_ptr, format);   
         if (vsnprintf(buf, sizeof buf, format, arg_ptr) == -1)
 		buf[sizeof buf - 2] = '\n';
 	client_write(buf, strlen(buf)); 
 	va_end(arg_ptr);
-	}   
+}   
 
 
 /*
@@ -517,7 +497,8 @@ void cprintf(const char *format, ...) {
  * Return values are:
  *	1	Requested number of bytes has been read.
  *	0	Request timed out.
- * If the socket breaks, the session is immediately terminated.
+ *	-1	The socket is broken.
+ * If the socket breaks, the session will be terminated.
  */
 int client_read_to(char *buf, int bytes, int timeout)
 {
@@ -535,20 +516,22 @@ int client_read_to(char *buf, int bytes, int timeout)
 
 		retval = select( (CC->client_socket)+1, 
 					&rfds, NULL, NULL, &tv);
+
 		if (FD_ISSET(CC->client_socket, &rfds) == 0) {
 			return(0);
-			}
+		}
 
 		rlen = read(CC->client_socket, &buf[len], bytes-len);
 		if (rlen<1) {
 			lprintf(2, "client_read() failed: %s\n",
 				strerror(errno));
-			cleanup(errno);
-			}
-		len = len + rlen;
+			CC->kill_me = 1;
+			return(-1);
 		}
-	return(1);
+		len = len + rlen;
 	}
+	return(1);
+}
 
 /*
  * Read data from the client socket with default timeout.
@@ -558,7 +541,7 @@ int client_read_to(char *buf, int bytes, int timeout)
 int client_read(char *buf, int bytes)
 {
 	return(client_read_to(buf, bytes, config.c_sleeping));
-	}
+}
 
 
 /*
@@ -574,13 +557,13 @@ int client_gets(char *buf)
 	 */
 	for (i = 0;;i++) {
 		retval = client_read(&buf[i], 1);
-		if (retval != 1 || buf[i] == '\n' || i == 255)
+		if (retval != 1 || buf[i] == '\n' || i == (SIZ-1))
 			break;
-		}
+	}
 
 	/* If we got a long line, discard characters until the newline.
 	 */
-	if (i == 255)
+	if (i == (SIZ-1))
 		while (buf[i] != '\n' && retval == 1)
 			retval = client_read(&buf[i], 1);
 
@@ -589,8 +572,9 @@ int client_gets(char *buf)
 	buf[i] = 0;
 	while ((strlen(buf)>0)&&(!isprint(buf[strlen(buf)-1])))
 		buf[strlen(buf)-1] = 0;
+	if (retval < 0) strcpy(buf, "000");
 	return(retval);
-	}
+}
 
 
 
@@ -598,59 +582,50 @@ int client_gets(char *buf)
  * The system-dependent part of master_cleanup() - close the master socket.
  */
 void sysdep_master_cleanup(void) {
-	lprintf(7, "Closing master socket %d\n", msock);
-	close(msock);
-	}
+	struct ServiceFunctionHook *serviceptr;
 
-/*
- * Cleanup routine to be called when one thread is shutting down.
- */
-void cleanup(int exit_code)
-{
-	/* Terminate the thread.
-	 * Its cleanup handler will call cleanup_stuff()
+	/*
+	 * close all protocol master sockets
 	 */
-	lprintf(7, "Calling pthread_exit()\n");
-	pthread_exit(NULL);
+	for (serviceptr = ServiceHookTable; serviceptr != NULL;
+	    serviceptr = serviceptr->next ) {
+
+		if (serviceptr->tcp_port > 0)
+			lprintf(3, "Closing listener on port %d\n",
+				serviceptr->tcp_port);
+
+		if (serviceptr->sockpath != NULL)
+			lprintf(3, "Closing listener on '%s'\n",
+				serviceptr->sockpath);
+
+		close(serviceptr->msock);
+
+		/* If it's a Unix domain socket, remove the file. */
+		if (serviceptr->sockpath != NULL) {
+			unlink(serviceptr->sockpath);
+		}
 	}
+}
+
 
 /*
  * Terminate another session.
+ * (This could justifiably be moved out of sysdep.c because it
+ * no longer does anything that is system-dependent.)
  */
 void kill_session(int session_to_kill) {
 	struct CitContext *ptr;
-	THREAD killme = 0;
 
-	lprintf(9, "kill_session() scanning for thread to cancel...\n");
 	begin_critical_section(S_SESSION_TABLE);
 	for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
 		if (ptr->cs_pid == session_to_kill) {
-			killme = ptr->mythread;
-			}
-		}
-	end_critical_section(S_SESSION_TABLE);
-	lprintf(9, "kill_session() finished scanning.\n");
-
-	if (killme != 0) {
-#ifdef HAVE_PTHREAD_CANCEL
-		lprintf(9, "calling pthread_cancel()\n");
-		pthread_cancel(killme);
-#else
-		pthread_kill(killme, SIGUSR1);
-#endif
+			ptr->kill_me = 1;
 		}
 	}
+	end_critical_section(S_SESSION_TABLE);
+}
 
 
-/*
- * The system-dependent wrapper around the main context loop.
- */
-void *sd_context_loop(struct CitContext *con) {
-	pthread_cleanup_push(*cleanup_stuff, NULL);
-	context_loop(con);
-	pthread_cleanup_pop(0);
-	return NULL;
-	}
 
 
 /*
@@ -661,12 +636,12 @@ void start_daemon(int do_close_stdio) {
 		/* close(0); */
 		close(1);
 		close(2);
-		}
+	}
 	signal(SIGHUP,SIG_IGN);
 	signal(SIGINT,SIG_IGN);
 	signal(SIGQUIT,SIG_IGN);
 	if (fork()!=0) exit(0);
-	}
+}
 
 
 
@@ -682,13 +657,13 @@ void cmd_nset(char *cmdbuf)
 	FILE *netsetup;
 	int ch;
 	int a, b;
-	char netsetup_args[3][256];
+	char netsetup_args[3][SIZ];
 
 	if (CC->usersupp.axlevel < 6) {
 		cprintf("%d Higher access required.\n", 
 			ERROR + HIGHER_ACCESS_REQUIRED);
 		return;
-		}
+	}
 
 	for (a=1; a<=3; ++a) {
 		if (num_parms(cmdbuf) >= a) {
@@ -696,13 +671,13 @@ void cmd_nset(char *cmdbuf)
 			for (b=0; b<strlen(netsetup_args[a-1]); ++b) {
 				if (netsetup_args[a-1][b] == 34) {
 					netsetup_args[a-1][b] = '_';
-					}
 				}
 			}
+		}
 		else {
 			netsetup_args[a-1][0] = 0;
-			}
 		}
+	}
 
 	sprintf(fbuf, "./netsetup \"%s\" \"%s\" \"%s\" </dev/null 2>&1",
 		netsetup_args[0], netsetup_args[1], netsetup_args[2]);
@@ -710,30 +685,30 @@ void cmd_nset(char *cmdbuf)
 	if (netsetup == NULL) {
 		cprintf("%d %s\n", ERROR, strerror(errno));
 		return;
-		}
+	}
 
 	fbuf[0] = 0;
 	while (ch = getc(netsetup), (ch > 0)) {
 		fbuf[strlen(fbuf)+1] = 0;
 		fbuf[strlen(fbuf)] = ch;
-		}
+	}
 
 	retcode = pclose(netsetup);
 
 	if (retcode != 0) {
 		for (a=0; a<strlen(fbuf); ++a) {
 			if (fbuf[a] < 32) fbuf[a] = 32;
-			}
+		}
 		fbuf[245] = 0;
 		cprintf("%d %s\n", ERROR, fbuf);
 		return;
-		}
+	}
 
 	cprintf("%d Command succeeded.  Output follows:\n", LISTING_FOLLOWS);
 	cprintf("%s", fbuf);
 	if (fbuf[strlen(fbuf)-1] != 10) cprintf("\n");
 	cprintf("000\n");
-	}
+}
 
 
 
@@ -748,43 +723,212 @@ int convert_login(char NameToConvert[]) {
 	pw = getpwnam(NameToConvert);
 	if (pw == NULL) {
 		return(0);
-		}
+	}
 	else {
 		strcpy(NameToConvert, pw->pw_gecos);
 		for (a=0; a<strlen(NameToConvert); ++a) {
 			if (NameToConvert[a] == ',') NameToConvert[a] = 0;
-			}
-		return(1);
 		}
+		return(1);
 	}
+}
+
+static struct worker_node {
+	pthread_t tid;
+	struct worker_node *next;
+} *worker_list = NULL;
+
 
+/*
+ * create a worker thread. this function must always be called from within
+ * an S_WORKER_LIST critical section!
+ */
+static void create_worker(void) {
+	int ret;
+	struct worker_node *n = mallok(sizeof *n);
+
+	if (n == NULL) {
+		lprintf(1, "can't allocate worker_node, exiting\n");
+		time_to_die = -1;
+		return;
+	}
 
+	if ((ret = pthread_create(&n->tid, NULL, worker_thread, NULL) != 0))
+	{
 
+		lprintf(1, "Can't create worker thread: %s\n",
+			strerror(ret));
+	}
 
+	n->next = worker_list;
+	worker_list = n;
+}
+
+
+
+/*
+ * Purge all sessions which have the 'kill_me' flag set.
+ * This function has code to prevent it from running more than once every
+ * few seconds, because running it after every single unbind would waste a lot
+ * of CPU time and keep the context list locked too much.
+ *
+ * After that's done, we raise or lower the size of the worker thread pool
+ * if such an action is appropriate.
+ */
+void dead_session_purge(void) {
+	struct CitContext *ptr, *rem;
+	struct worker_node **node, *tmp;
+	pthread_t self;
+
+	if ( (time(NULL) - last_purge) < 5 ) return;	/* Too soon, go away */
+	time(&last_purge);
+
+	do {
+		rem = NULL;
+		begin_critical_section(S_SESSION_TABLE);
+		for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
+			if ( (ptr->state == CON_IDLE) && (ptr->kill_me) ) {
+				rem = ptr;
+			}
+		}
+		end_critical_section(S_SESSION_TABLE);
+
+		/* RemoveContext() enters its own S_SESSION_TABLE critical
+		 * section, so we have to do it like this.
+		 */	
+		if (rem != NULL) {
+			lprintf(9, "Purging session %d\n", rem->cs_pid);
+			RemoveContext(rem);
+		}
+
+	} while (rem != NULL);
+
+
+	/* Raise or lower the size of the worker thread pool if such
+	 * an action is appropriate.
+	 */
+
+	self = pthread_self();
+
+	if ( (num_sessions > num_threads)
+	   && (num_threads < config.c_max_workers) ) {
+		begin_critical_section(S_WORKER_LIST);
+		create_worker();
+		end_critical_section(S_WORKER_LIST);
+	}
 	
+	/* don't let the initial thread die since it's responsible for
+	   waiting for all the other threads to terminate. */
+	else if ( (num_sessions < num_threads)
+	   && (num_threads > config.c_min_workers)
+	   && (self != initial_thread) ) {
+		cdb_free_tsd();
+		begin_critical_section(S_WORKER_LIST);
+		--num_threads;
+
+		/* we're exiting before server shutdown... unlink ourself from
+		   the worker list and detach our thread to avoid memory leaks
+		 */
+
+		for (node = &worker_list; *node != NULL; node = &(*node)->next)
+			if ((*node)->tid == self) {
+				tmp = *node;
+				*node = (*node)->next;
+				phree(tmp);
+				break;
+			}
+
+		pthread_detach(self);
+		end_critical_section(S_WORKER_LIST);
+		pthread_exit(NULL);
+	}
+
+}
+
+
+
+
+
+/*
+ * Redirect a session's output to a file or socket.
+ * This function may be called with a file handle *or* a socket (but not
+ * both).  Call with neither to return output to its normal client socket.
+ */
+void CtdlRedirectOutput(FILE *fp, int sock) {
+
+	if (fp != NULL) CC->redirect_fp = fp;
+	else CC->redirect_fp = NULL;
+
+	if (sock > 0) CC->redirect_sock = sock;
+	else CC->redirect_sock = (-1);
+
+}
+
+
+/*
+ * masterCC is the context we use when not attached to a session.  This
+ * function initializes it.
+ */
+void InitializeMasterCC(void) {
+	memset(&masterCC, 0, sizeof(struct CitContext));
+	masterCC.internal_pgm = 1;
+	masterCC.cs_pid = 0;
+}
+
+
+
+/*
+ * Set up a fd_set containing all the master sockets to which we
+ * always listen.  It's computationally less expensive to just copy
+ * this to a local fd_set when starting a new select() and then add
+ * the client sockets than it is to initialize a new one and then
+ * figure out what to put there.
+ */
+void init_master_fdset(void) {
+	struct ServiceFunctionHook *serviceptr;
+	int m;
+
+	lprintf(9, "Initializing master fdset\n");
+
+	FD_ZERO(&masterfds);
+	masterhighest = 0;
+
+	lprintf(9, "Will listen on rescan pipe %d\n", rescan[0]);
+	FD_SET(rescan[0], &masterfds);
+	if (rescan[0] > masterhighest) masterhighest = rescan[0];
+
+	for (serviceptr = ServiceHookTable; serviceptr != NULL;
+	    serviceptr = serviceptr->next ) {
+		m = serviceptr->msock;
+		lprintf(9, "Will listen on master socket %d\n", m);
+		FD_SET(m, &masterfds);
+		if (m > masterhighest) {
+			masterhighest = m;
+		}
+	}
+	lprintf(9, "masterhighest = %d\n", masterhighest);
+}
+
+
 
 /*
  * Here's where it all begins.
  */
 int main(int argc, char **argv)
 {
-	struct sockaddr_in fsin;	/* Data for master socket */
-	int alen;			/* Data for master socket */
-	int ssock;			/* Descriptor for master socket */
-	THREAD SessThread;		/* Thread descriptor */
-        pthread_attr_t attr;		/* Thread attributes */
-	struct CitContext *con;		/* Temporary context pointer */
 	char tracefile[128];		/* Name of file to log traces to */
 	int a, i;			/* General-purpose variables */
-	char convbuf[128];
-	fd_set readfds;
-	struct timeval tv;
 	struct passwd *pw;
 	int drop_root_perms = 1;
+	char *moddir;
+	struct worker_node *wnp;
         
 	/* specify default port name and trace file */
 	strcpy(tracefile, "");
 
+	/* initialize the master context */
+	InitializeMasterCC();
+
 	/* parse command-line arguments */
 	for (a=1; a<argc; ++a) {
 
@@ -795,24 +939,27 @@ int main(int argc, char **argv)
 			freopen(tracefile, "r", stdin);
 			freopen(tracefile, "w", stdout);
 			freopen(tracefile, "w", stderr);
-			}
+		}
 
 		/* run in the background if -d was specified */
 		else if (!strcmp(argv[a], "-d")) {
 			start_daemon( (strlen(tracefile) > 0) ? 0 : 1 ) ;
-			}
+		}
 
 		/* -x specifies the desired logging level */
 		else if (!strncmp(argv[a], "-x", 2)) {
-			strcpy(convbuf, argv[a]);
-			verbosity = atoi(&convbuf[2]);
-			}
+			verbosity = atoi(&argv[a][2]);
+		}
 
 		else if (!strncmp(argv[a], "-h", 2)) {
-			strcpy(convbuf, argv[a]);
-			strcpy(bbs_home_directory, &convbuf[2]);
+			safestrncpy(bbs_home_directory, &argv[a][2],
+				    sizeof bbs_home_directory);
 			home_specified = 1;
-			}
+		}
+
+		else if (!strncmp(argv[a], "-f", 2)) {
+			do_defrag = 1;
+		}
 
 		/* -r tells the server not to drop root permissions. don't use
 		 * this unless you know what you're doing. this should be
@@ -822,37 +969,78 @@ int main(int argc, char **argv)
 
 		/* any other parameter makes it crash and burn */
 		else {
-			lprintf(1, "citserver: usage: ");
-			lprintf(1, "citserver [-tTraceFile]");
-			lprintf(1, " [-d] [-xLogLevel] [-hHomeDir]\n");
+			lprintf(1,	"citserver: usage: "
+					"citserver [-tTraceFile] [-d] [-f]"
+					" [-xLogLevel] [-hHomeDir]\n");
 			exit(1);
-			}
-
 		}
 
+	}
+
 	/* Tell 'em who's in da house */
-	lprintf(1, "Multithreaded message server for %s\n", CITADEL);
-	lprintf(1, "Copyright (C) 1987-1999 by Art Cancro.  ");
-	lprintf(1, "All rights reserved.\n\n");
+	lprintf(1,
+"\nMultithreaded message server for Citadel/UX\n"
+"Copyright (C) 1987-2000 by the Citadel/UX development team.\n"
+"Citadel/UX is free software, covered by the GNU General Public License, and\n"
+"you are welcome to change it and/or distribute copies of it under certain\n"
+"conditions.  There is absolutely no warranty for this software.  Please\n"
+"read the 'COPYING.txt' file for details.\n\n");
 
 	/* Initialize... */
 	init_sysdep();
-	openlog("citserver",LOG_PID,LOG_USER);
+	openlog("citserver", LOG_PID, LOG_USER);
+
 	/* Load site-specific parameters */
 	lprintf(7, "Loading citadel.config\n");
 	get_config();
 
+
+	/*
+	 * Do non system dependent startup functions.
+	 */
+	master_startup();
+
+	/*
+	 * Bind the server to a Unix-domain socket.
+	 */
+	CtdlRegisterServiceHook(0,
+				"citadel.socket",
+				citproto_begin_session,
+				do_command_loop);
+
+	/*
+	 * Bind the server to our favorite TCP port (usually 504).
+	 */
+	CtdlRegisterServiceHook(config.c_port_number,
+				NULL,
+				citproto_begin_session,
+				do_command_loop);
+
+	/*
+	 * Load any server-side modules (plugins) available here.
+	 */
+	lprintf(7, "Initializing loadable modules\n");
+	if ((moddir = malloc(strlen(bbs_home_directory) + 9)) != NULL) {
+		sprintf(moddir, "%s/modules", bbs_home_directory);
+		DLoader_Init(moddir);
+		free(moddir);
+	}
+
 	/*
-	 * Bind the server to our favourite port.
-	 * There is no need to check for errors, because ig_tcp_server()
-	 * exits if it doesn't succeed.
+	 * The rescan pipe exists so that worker threads can be woken up and
+	 * told to re-scan the context list for fd's to listen on.  This is
+	 * necessary, for example, when a context is about to go idle and needs
+	 * to get back on that list.
 	 */
-	lprintf(7, "Attempting to bind to port %d...\n", config.c_port_number);
-	msock = ig_tcp_server(config.c_port_number, 5);
-	lprintf(7, "Listening on socket %d\n", msock);
+	if (pipe(rescan)) {
+		lprintf(1, "Can't create rescan pipe!\n");
+		exit(errno);
+	}
+
+	init_master_fdset();
 
 	/*
-	 * Now that we've bound the socket, change to the BBS user id and its
+	 * Now that we've bound the sockets, change to the BBS user id and its
 	 * corresponding group ids
 	 */
 	if (drop_root_perms) {
@@ -861,90 +1049,254 @@ int main(int argc, char **argv)
 				   "Group IDs will be incorrect.\n", BBSUID,
 				strerror(errno));
 		else {
-			if (initgroups(pw->pw_name, pw->pw_gid))
-				lprintf(3, "initgroups(): %s\n",
-					strerror(errno));
+			initgroups(pw->pw_name, pw->pw_gid);
 			if (setgid(pw->pw_gid))
 				lprintf(3, "setgid(%d): %s\n", pw->pw_gid,
 					strerror(errno));
-			}
+		}
 		lprintf(7, "Changing uid to %d\n", BBSUID);
 		if (setuid(BBSUID) != 0) {
 			lprintf(3, "setuid() failed: %s\n", strerror(errno));
-			}
 		}
+	}
 
-	lprintf(7, "Initializing loadable modules\n");
-	DLoader_Init("./modules");
-	lprintf(9, "Modules done initializing.\n");
+	/* We want to check for idle sessions once per minute */
+	CtdlRegisterSessionHook(terminate_idle_sessions, EVT_TIMER);
 
 	/*
-	 * Do non system dependent startup functions.
+	 * Now create a bunch of worker threads.
 	 */
-	master_startup();
+	lprintf(9, "Starting %d worker threads\n", config.c_min_workers-1);
+	begin_critical_section(S_WORKER_LIST);
+	for (i=0; i<(config.c_min_workers-1); ++i) {
+		create_worker();
+	}
+	end_critical_section(S_WORKER_LIST);
+
+	/* Now this thread can become a worker as well. */
+	initial_thread = pthread_self();
+	worker_thread(NULL);
+
+	/* Server is exiting. Wait for workers to shutdown. */
+	lprintf(7, "Waiting for worker threads to shut down\n");
+
+	begin_critical_section(S_WORKER_LIST);
+	while (worker_list != NULL) {
+		wnp = worker_list;
+		worker_list = wnp->next;
+
+		/* avoid deadlock with an exiting thread */
+		end_critical_section(S_WORKER_LIST);
+		if ((i = pthread_join(wnp->tid, NULL)))
+			lprintf(1, "pthread_join: %s\n", strerror(i));
+		phree(wnp);
+		begin_critical_section(S_WORKER_LIST);
+	}
+	end_critical_section(S_WORKER_LIST);
+
+	master_cleanup();
+
+	return(0);
+}
+
+
+/*
+ * Bind a thread to a context.  (It's inline merely to speed things up.)
+ */
+inline void become_session(struct CitContext *which_con) {
+	pthread_setspecific(MyConKey, (void *)which_con );
+}
+
+
+
+/* 
+ * This loop just keeps going and going and going...
+ */	
+void *worker_thread(void *arg) {
+	int i;
+	char junk;
+	int highest;
+	struct CitContext *ptr;
+	struct CitContext *bind_me = NULL;
+	fd_set readfds;
+	int retval;
+	struct CitContext *con= NULL;	/* Temporary context pointer */
+	struct ServiceFunctionHook *serviceptr;
+	struct sockaddr_in fsin;	/* Data for master socket */
+	int alen;			/* Data for master socket */
+	int ssock;			/* Descriptor for client socket */
+	struct timeval tv;
+
+	num_threads++;
+
+	cdb_allocate_tsd();
 
-	/* 
-	 * Endless loop.  Listen on the master socket.  When a connection
-	 * comes in, create a socket, a context, and a thread.
-	 */	
 	while (!time_to_die) {
-		/* we need to check if a signal has been delivered. because
-		 * syscalls may be restartable across signals, we call
-		 * select with a timeout of 1 second and repeatedly check for
-		 * time_to_die... */
-		FD_ZERO(&readfds);
-		FD_SET(msock, &readfds);
-		tv.tv_sec = 1;
+
+		/* 
+		 * A naive implementation would have all idle threads
+		 * calling select() and then they'd all wake up at once.  We
+		 * solve this problem by putting the select() in a critical
+		 * section, so only one thread has the opportunity to wake
+		 * up.  If we wake up on a master socket, create a new
+		 * session context; otherwise, just bind the thread to the
+		 * context we want and go on our merry way.
+		 */
+
+		/* make doubly sure we're not holding any stale db handles
+		 * which might cause a deadlock.
+		 */
+		cdb_check_handles();
+
+		begin_critical_section(S_I_WANNA_SELECT);
+SETUP_FD:	memcpy(&readfds, &masterfds, sizeof masterfds);
+		highest = masterhighest;
+		begin_critical_section(S_SESSION_TABLE);
+		for (ptr = ContextList; ptr != NULL; ptr = ptr->next) {
+			if (ptr->state == CON_IDLE) {
+				FD_SET(ptr->client_socket, &readfds);
+				if (ptr->client_socket > highest)
+					highest = ptr->client_socket;
+			}
+		}
+		end_critical_section(S_SESSION_TABLE);
+
+		tv.tv_sec = 1;		/* wake up every second if no input */
 		tv.tv_usec = 0;
-		if (select(msock + 1, &readfds, NULL, NULL, &tv) <= 0)
-			continue;
-		alen = sizeof fsin;
-		ssock = accept(msock, (struct sockaddr *)&fsin, &alen);
-		if (ssock < 0) {
-			lprintf(2, "citserver: accept() failed: %s\n",
-				strerror(errno));
+
+		do_select:
+		if (!time_to_die)
+			retval = select(highest + 1, &readfds, NULL, NULL, &tv);
+		else {
+			end_critical_section(S_I_WANNA_SELECT);
+			break;
+		}
+
+		/* Now figure out who made this select() unblock.
+		 * First, check for an error or exit condition.
+		 */
+		if (retval < 0) {
+			if (errno != EINTR) {
+				lprintf(9, "Exiting (%s)\n", strerror(errno));
+				time_to_die = 1;
+			} else if (!time_to_die)
+				goto do_select;
+		}
+
+		/* Next, check to see if it's a new client connecting
+		 * on a master socket.
+		 */
+		else for (serviceptr = ServiceHookTable; serviceptr != NULL;
+		     serviceptr = serviceptr->next ) {
+
+			if (FD_ISSET(serviceptr->msock, &readfds)) {
+				alen = sizeof fsin;
+				ssock = accept(serviceptr->msock,
+					(struct sockaddr *)&fsin, &alen);
+				if (ssock < 0) {
+					lprintf(2, "citserver: accept(): %s\n",
+						strerror(errno));
+				}
+				else {
+					lprintf(7, "citserver: "
+						"New client socket %d\n",
+						ssock);
+
+					/* New context will be created already
+				 	* set up in the CON_EXECUTING state.
+				 	*/
+					con = CreateNewContext();
+
+					/* Assign new socket number to it. */
+					con->client_socket = ssock;
+					con->h_command_function =
+						serviceptr->h_command_function;
+
+					/* Determine whether local socket */
+					if (serviceptr->sockpath != NULL)
+						con->is_local_socket = 1;
+	
+					/* Set the SO_REUSEADDR socket option */
+					i = 1;
+					setsockopt(ssock, SOL_SOCKET,
+						SO_REUSEADDR,
+						&i, sizeof(i));
+
+					become_session(con);
+					begin_session(con);
+					serviceptr->h_greeting_function();
+					become_session(NULL);
+					con->state = CON_IDLE;
+					goto SETUP_FD;
+				}
 			}
+		}
+
+		/* If the rescan pipe went active, someone is telling this
+		 * thread that the &readfds needs to be refreshed with more
+		 * current data.
+		 */
+		if (time_to_die) {
+			end_critical_section(S_I_WANNA_SELECT);
+			break;
+		}
+
+		if (FD_ISSET(rescan[0], &readfds)) {
+			read(rescan[0], &junk, 1);
+			goto SETUP_FD;
+		}
+
+		/* It must be a client socket.  Find a context that has data
+		 * waiting on its socket *and* is in the CON_IDLE state.
+		 */
 		else {
-			lprintf(7, "citserver: Client socket %d\n", ssock);
-			lprintf(9, "creating context\n");
-			con = CreateNewContext();
-			con->client_socket = ssock;
-
-			/* Set the SO_REUSEADDR socket option */
-			lprintf(9, "setting socket options\n");
-			i = 1;
-			setsockopt(ssock, SOL_SOCKET, SO_REUSEADDR,
-				&i, sizeof(i));
-
-			/* set attributes for the new thread */
-			lprintf(9, "setting thread attributes\n");
-		        pthread_attr_init(&attr);
-        		pthread_attr_setdetachstate(&attr,
-				PTHREAD_CREATE_DETACHED);
-
-			/* now create the thread */
-			lprintf(9, "creating thread\n");
-			if (pthread_create(&SessThread, &attr,
-					   (void* (*)(void*)) sd_context_loop,
-					   con)
-			    != 0) {
-				lprintf(1,
-					"citserver: can't create thread: %s\n",
-					strerror(errno));
+			bind_me = NULL;
+			begin_critical_section(S_SESSION_TABLE);
+			for (ptr = ContextList;
+			    ( (ptr != NULL) && (bind_me == NULL) );
+			    ptr = ptr->next) {
+				if ( (FD_ISSET(ptr->client_socket, &readfds))
+				   && (ptr->state == CON_IDLE) ) {
+					bind_me = ptr;
 				}
+			}
+			if (bind_me != NULL) {
+				/* Found one.  Stake a claim to it before
+				 * letting anyone else touch the context list.
+				 */
+				bind_me->state = CON_EXECUTING;
+			}
 
-			/* detach the thread 
-   			 * (defunct -- now done at thread creation time)
-			 * if (pthread_detach(&SessThread) != 0) {
-			 *	lprintf(1,
-			 *		"citserver: can't detach thread: %s\n",
-			 *		strerror(errno));
-			 *	}
-			 */
-			lprintf(9, "done!\n");
+			end_critical_section(S_SESSION_TABLE);
+			end_critical_section(S_I_WANNA_SELECT);
+
+			/* We're bound to a session, now do *one* command */
+			if (bind_me != NULL) {
+				become_session(bind_me);
+				CC->h_command_function();
+				become_session(NULL);
+				bind_me->state = CON_IDLE;
+				if (bind_me->kill_me == 1) {
+					RemoveContext(bind_me);
+				} 
+				write(rescan[1], &junk, 1);
 			}
+
 		}
-	master_cleanup();
-	return 0;
+		dead_session_purge();
+		if ((time(NULL) - last_timer) > 60L) {
+			last_timer = time(NULL);
+			cdb_check_handles(); /* suggested by Justin Case */
+			PerformSessionHooks(EVT_TIMER);
+		}
+
+		check_sched_shutdown();
 	}
 
+	/* If control reaches this point, the server is shutting down */	
+	--num_threads;
+	return NULL;
+}
+
+
+