Fancier protocol for control socket

* pass error status back
* pass message boundaries

src/control.c

@@ -24,6 +24,7 @@
 #include "system.h"
 #include "conf.h"
 #include "control.h"
+#include "control_common.h"
 #include "logger.h"
 #include "xalloc.h"
 
@@ -33,17 +34,58 @@ static splay_tree_t *control_socket_tree;
 extern char *controlsocketname;
 
 static void handle_control_data(struct bufferevent *event, void *data) {
-	char *line = evbuffer_readline(event->input);
-	if(!line)
+	tinc_ctl_request_t req;
+	size_t size;
+	tinc_ctl_request_t res;
+	struct evbuffer *res_data = NULL;
+
+	if(EVBUFFER_LENGTH(event->input) < sizeof(tinc_ctl_request_t))
 		return;
 
-	if(!strcasecmp(line, "stop")) {
+	/* Copy the structure to ensure alignment */
+	memcpy(&req, EVBUFFER_DATA(event->input), sizeof(tinc_ctl_request_t));
+
+	if(EVBUFFER_LENGTH(event->input) < req.length)
+		return;
+
+	if(req.length < sizeof(tinc_ctl_request_t))
+		goto failure;
+
+	memset(&res, 0, sizeof res);
+	res.type = req.type;
+	res.id = req.id;
+
+	res_data = evbuffer_new();
+	if (res_data == NULL) {
+		res.res_errno = ENOMEM;
+		goto respond;
+	}
+
+	if(req.type == REQ_STOP) {
 		logger(LOG_NOTICE, _("Got stop command"));
 		event_loopexit(NULL);
-		return;
+		goto respond;
 	}
 
 	logger(LOG_DEBUG, _("Malformed control command received"));
+	res.res_errno = EINVAL;
+
+respond:
+	res.length = (sizeof res)
+				 + ((res_data == NULL) ? 0 : EVBUFFER_LENGTH(res_data));
+	evbuffer_drain(event->input, req.length);
+	if(bufferevent_write(event, &res, sizeof res) == -1)
+		goto failure;
+	if(res_data != NULL) {
+		if(bufferevent_write_buffer(event, res_data) == -1)
+			goto failure;
+		evbuffer_free(res_data);
+	}
+	return;
+
+failure:
+	logger(LOG_INFO, _("Closing control socket on error"));
+	evbuffer_free(res_data);
 	close(event->ev_read.ev_fd);
 	splay_delete(control_socket_tree, event);
 }
@@ -61,6 +103,7 @@ static void handle_control_error(struct bufferevent *event, short what, void *da
 static void handle_new_control_socket(int fd, short events, void *data) {
 	int newfd;
 	struct bufferevent *ev;
+	tinc_ctl_greeting_t greeting;
 
 	newfd = accept(fd, NULL, NULL);
 
@@ -77,6 +120,17 @@ static void handle_new_control_socket(int fd, short events, void *data) {
 		return;
 	}
 
+	memset(&greeting, 0, sizeof greeting);
+	greeting.version = TINC_CTL_VERSION_CURRENT;
+	if(bufferevent_write(ev, &greeting, sizeof greeting) == -1) {
+		logger(LOG_ERR,
+			   _("Cannot send greeting for new control connection: %s"),
+			   strerror(errno));
+		bufferevent_free(ev);
+		close(newfd);
+		return;
+	}
+
 	bufferevent_enable(ev, EV_READ);
 	splay_insert(control_socket_tree, ev);
 

src/control_common.h

@@ -0,0 +1,46 @@
+/*
+    control_protocol.h -- control socket protocol.
+    Copyright (C) 2007 Scott Lamb <slamb@slamb.org>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+    $Id$
+*/
+
+#ifndef __TINC_CONTROL_PROTOCOL_H__
+#define __TINC_CONTROL_PROTOCOL_H__
+
+enum request_type {
+	REQ_STOP,
+	REQ_RELOAD,
+	REQ_RESTART,
+};
+
+#define TINC_CTL_VERSION_CURRENT 0
+
+/* This greeting is sent by the server on socket open. */
+typedef struct tinc_ctl_greeting_t {
+	int version;
+} tinc_ctl_greeting_t;
+
+/* A single request or response header. */
+typedef struct tinc_ctl_request_t {
+	size_t length; /* total length, including the header */
+	enum request_type type;
+	int id;
+	int res_errno; /* used only for responses */
+} tinc_ctl_request_t;
+
+#endif

src/tincctl.c

@@ -30,8 +30,9 @@
 
 #include <getopt.h>
 
-#include "protocol.h"
 #include "xalloc.h"
+#include "protocol.h"
+#include "control_common.h"
 
 /* The name this program was run with. */
 char *program_name = NULL;
@@ -327,9 +328,118 @@ static void make_names(void) {
 	}
 }
 
+static int fullread(int fd, void *data, size_t datalen) {
+	int rv, len = 0;
+
+	while (len < datalen) {
+		rv = read(fd, data + len, datalen - len);
+		if(rv == -1 && errno == EINTR)
+			continue;
+		else if (rv == -1)
+			return rv;
+		else if (rv == 0) {
+			errno = ENODATA;
+			return -1;
+		}
+		len += rv;
+	}
+	return 0;
+}
+
+/*
+   Send a request (raw)
+*/
+static int send_ctl_request(int fd, enum request_type type,
+						   void const *outdata, size_t outdatalen,
+						   int *res_errno_p, void **indata_p,
+						   size_t *indatalen_p) {
+	tinc_ctl_request_t req;
+	int rv;
+	struct iovec vector[2] = {
+		{&req, sizeof(req)},
+		{(void*) outdata, outdatalen}
+	};
+	void *indata;
+
+	if(res_errno_p == NULL)
+		return -1;
+
+	memset(&req, 0, sizeof req);
+	req.length = sizeof req + outdatalen;
+	req.type = type;
+	req.res_errno = 0;
+
+	while((rv = writev(fd, vector, 2)) == -1 && errno == EINTR) ;
+	if(rv != req.length)
+		return -1;
+
+	if(fullread(fd, &req, sizeof req) == -1)
+		return -1;
+
+	if(req.length < sizeof req) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if(req.length > sizeof req) {
+		if (indata_p == NULL) {
+			errno = EINVAL;
+			return -1;
+		}
+
+		indata = xmalloc(req.length - sizeof req);
+
+		if(fullread(fd, indata, req.length - sizeof req) == -1) {
+			free(indata);
+			return -1;
+		}
+
+		*indata_p = indata;
+		if(indatalen_p != NULL)
+			*indatalen_p = req.length - sizeof req;
+	}
+
+	*res_errno_p = req.res_errno;
+
+	return 0;
+}
+
+/*
+   Send a request (with printfs)
+*/
+static int send_ctl_request_cooked(int fd, enum request_type type,
+								   void const *outdata, size_t outdatalen)
+{
+	int res_errno = -1;
+	char *buf = NULL;
+	size_t buflen = 0;
+
+	if(send_ctl_request(fd, type, outdata, outdatalen, &res_errno,
+						(void**) &buf, &buflen)) {
+		fprintf(stderr, _("Error sending request: %s\n"), strerror(errno));
+		return -1;
+	}
+
+	if(buf != NULL) {
+		printf("%*s", buflen, buf);
+		free(buf);
+	}
+
+	if(res_errno != 0) {
+		fprintf(stderr, _("Server reported error: %s\n"), strerror(res_errno));
+		return -1;
+	}
+
+	return 0;
+}
+
 int main(int argc, char *argv[], char *envp[]) {
-	int fd;
 	struct sockaddr_un addr;
+	int fd;
+	int len;
+	tinc_ctl_greeting_t greeting;
+	tinc_ctl_request_t req;
+
 	program_name = argv[0];
 
 	setlocale(LC_ALL, "");
@@ -399,6 +509,18 @@ int main(int argc, char *argv[], char *envp[]) {
 		return 1;
 	}
 
+	if(fullread(fd, &greeting, sizeof greeting) == -1) {
+		fprintf(stderr, _("Cannot read greeting from control socket: %s\n"),
+				strerror(errno));
+		return 1;
+	}
+
+	if(greeting.version != TINC_CTL_VERSION_CURRENT) {
+		fprintf(stderr, _("Version mismatch: server %d, client %d\n"),
+				greeting.version, TINC_CTL_VERSION_CURRENT);
+		return 1;
+	}
+
 	struct ucred cred;
 	socklen_t credlen = sizeof cred;
 
@@ -413,18 +535,15 @@ int main(int argc, char *argv[], char *envp[]) {
 	}
 
 	if(!strcasecmp(argv[optind], "stop")) {
-		write(fd, "stop\n", 5);
-		return 0;
+		return send_ctl_request_cooked(fd, REQ_STOP, NULL, 0) != -1;
 	}
 
 	if(!strcasecmp(argv[optind], "reload")) {
-		write(fd, "reload\n", 7);
-		return 0;
+		return send_ctl_request_cooked(fd, REQ_RELOAD, NULL, 0) != -1;
 	}
 	
 	if(!strcasecmp(argv[optind], "restart")) {
-		write(fd, "restart\n", 8);
-		return 0;
+		return send_ctl_request_cooked(fd, REQ_RESTART, NULL, 0) != -1;
 	}
 
 	fprintf(stderr, _("Unknown command `%s'.\n"), argv[optind]);