[Patch 1/3] CLD: use "auto" keyword

[Pete Zaitcev <zaitcev@redhat.com>]

The current implementation of automatic listening ports was configured
implicitly by adding <PortFile> clause. This turned out to be a silly
idea. A special keyword for <Port> is more convenient. See how much
nicer the test/start-daemon script looks now.

The configuration is not strictly speaking compatible, but since
nobody should be using auto ports in production anyway, impact on
installations should be nil. Builds are interdependent though.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>

diff --git a/server/cld.h b/server/cld.h
index e5ea9aa..7a353b1 100644
--- a/server/cld.h
+++ b/server/cld.h
@@ -112,9 +112,8 @@ struct server {
 	char			*pid_file;	/* PID file */
 	int			pid_fd;
 
-	char			*port;		/* bind port */
+	char			*port;		/* bind port, NULL means auto */
 	char			*port_file;	/* Port file to write */
-	bool			port_set;
 
 	struct cldb		cldb;		/* database info */
 
diff --git a/server/server.c b/server/server.c
index ef8a060..b01472a 100644
--- a/server/server.c
+++ b/server/server.c
@@ -61,14 +61,14 @@ static struct argp_option options[] = {
 	{ "foreground", 'F', NULL, 0,
 	  "Run in foreground, do not fork" },
 	{ "port", 'p', "PORT", 0,
-	  "bind to UDP port PORT.  Default: " CLD_DEF_PORT },
+	  "Bind to UDP port PORT.  Default: " CLD_DEF_PORT },
 	{ "pid", 'P', "FILE", 0,
 	  "Write daemon process id to FILE.  Default: " CLD_DEF_PIDFN },
 	{ "strict-free", 1001, NULL, 0,
 	  "For memory-checker runs.  When shutting down server, free local "
 	  "heap, rather than simply exit(2)ing and letting OS clean up." },
 	{ "port-file", 1002, "FILE", 0,
-	  "Write the listen port to FILE. Implies bind to zero." },
+	  "Write the listen port to FILE." },
 	{ }
 };
 
@@ -584,6 +584,23 @@ static void cldb_checkpoint(struct timer *timer)
 	add_chkpt_timer();
 }
 
+static int net_write_port(const char *port_file, const char *port_str)
+{
+	FILE *portf;
+	int rc;
+
+	portf = fopen(port_file, "w");
+	if (portf == NULL) {
+		rc = errno;
+		cldlog(LOG_INFO, "Cannot create port file %s: %s",
+		       port_file, strerror(rc));
+		return -rc;
+	}
+	fprintf(portf, "%s\n", port_str);
+	fclose(portf);
+	return 0;
+}
+
 static void net_close(void)
 {
 	struct pollfd *pfd;
@@ -619,9 +636,10 @@ static int net_open_socket(int addr_fam, int sock_type, int sock_prot,
 
 	on = 1;
 	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0) {
+		rc = errno;
 		syslogerr("setsockopt(SO_REUSEADDR)");
 		close(fd);
-		return -errno;
+		return -rc;
 	}
 
 	if (bind(fd, addr_ptr, addr_len) < 0) {
@@ -653,7 +671,6 @@ static int net_open_any(void)
 {
 	struct sockaddr_in addr4;
 	struct sockaddr_in6 addr6;
-	FILE *portf;
 	int fd4, fd6;
 	socklen_t addr_len;
 	unsigned short port;
@@ -700,16 +717,11 @@ static int net_open_any(void)
 
 	cldlog(LOG_INFO, "Listening on port %u", port);
 
-	portf = fopen(cld_srv.port_file, "w");
-	if (portf == NULL) {
-		rc = errno;
-		cldlog(LOG_INFO, "Cannot create port file %s: %s",
-		       cld_srv.port_file, strerror(rc));
-		return -rc;
+	if (cld_srv.port_file) {
+		char portstr[7];
+		snprintf(portstr, sizeof(portstr), "%u\n", port);
+		return net_write_port(cld_srv.port_file, portstr);
 	}
-	fprintf(portf, "%u\n", port);
-	fclose(portf);
-
 	return 0;
 }
 
@@ -772,6 +784,8 @@ static int net_open_known(const char *portstr)
 
 	freeaddrinfo(res0);
 
+	if (cld_srv.port_file)
+		return net_write_port(cld_srv.port_file, portstr);
 	return 0;
 
 err_out:
@@ -782,7 +796,7 @@ err_addr:
 
 static int net_open(void)
 {
-	if (cld_srv.port_file)
+	if (!cld_srv.port)
 		return net_open_any();
 	else
 		return net_open_known(cld_srv.port);
@@ -836,9 +850,15 @@ static error_t parse_opt (int key, char *arg, struct argp_state *state)
 		cld_srv.flags |= SFL_FOREGROUND;
 		break;
 	case 'p':
-		if (atoi(arg) > 0 && atoi(arg) < 65536) {
+		/*
+		 * We do not permit "0" as an argument in order to be safer
+		 * against a malfunctioning jumpstart script or a simple
+		 * misunderstanding by a human operator.
+		 */
+		if (!strcmp(arg, "auto")) {
+			cld_srv.port = NULL;
+		} else if (atoi(arg) > 0 && atoi(arg) < 65536) {
 			cld_srv.port = arg;
-			cld_srv.port_set = true;
 		} else {
 			fprintf(stderr, "invalid port: '%s'\n", arg);
 			argp_usage(state);
@@ -888,11 +908,6 @@ int main (int argc, char *argv[])
 		fprintf(stderr, "argp_parse failed: %s\n", strerror(aprc));
 		return 1;
 	}
-	if (cld_srv.port_set && cld_srv.port_file) {
-		fprintf(stderr, "Options --port and --port-file must not"
-			" be set together\n");
-		return 1;
-	}
 
 	/*
 	 * open syslog, background outselves, write PID file ASAP
diff --git a/test/start-daemon b/test/start-daemon
index fc27775..15d4546 100755
--- a/test/start-daemon
+++ b/test/start-daemon
@@ -7,11 +7,9 @@ then
 fi
 
 ## Static port
-# cldport=18181
-# echo $cldport > cld.port
-# ../server/cld -P cld.pid -d "$PWD/data" -p $cldport -E
+# ../server/cld -P cld.pid -d "$PWD/data" -p 18181 --port-file=cld.port -E
 ## Dynamic port
-../server/cld -P cld.pid -d "$PWD/data" --port-file=cld.port -E
+../server/cld -P cld.pid -d "$PWD/data" -p auto --port-file=cld.port -E
 
 sleep 3