Date:	Tue, 17 Dec 2013 12:00:22 +0900
From:	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Hidehiro Kawai <hidehiro.kawai.ez@...achi.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Aaron Fabbri <aaronx.j.fabbri@...el.com>,
	linux-kernel@...r.kernel.org, yrl.pp-manager.tt@...achi.com
Subject: [PATCH V3 2/6] trace-cmd: Apply the trace-msg protocol for
 communication between a server and clients

Apply trace-msg protocol for communication between a server and clients.

Currently, trace-listen(server) and trace-record -N(client) operate as follows:

     <server>                 <client>
      listen to socket fd
                              connect to socket fd
      accept the client
      send "tracecmd"
               +------------> receive "tracecmd"
                              check "tracecmd"
                              send cpus
      receive cpus <------------+
      print "cpus=XXX"
                              send pagesize
                                |
      receive pagesize <--------+
      print "pagesize=XXX"
                              send option
                                |
      receive option <----------+
      understand option
      send port_array
               +------------> receive port_array
                              understand port_array
                              send meta data
      receive meta data <-------+
      record meta data
                        (snip)
      read block
     --- start sending trace data on child processes ---

     --- When client finishes sending trace data ---
                              close(socket fd)
      read size = 0
      close(socket fd)

All messages are unstructured character strings, so server(client) using the
protocol must parse the unstructured messages. Since it is hard to
add complex contents in the protocol, structured binary message trace-msg
is introduced as the communication protocol.

By applying this patch, server and client operate as follows:

     <server>                 <client>
      listen to socket fd
                              connect to socket fd
      accept the client
      send "tracecmd"
               +------------> receive "tracecmd"
                              check "tracecmd"
                              send "V2\0<MAGIC_NUMBER>\00" as the v2 protocol
      receive "V2" <------------+
      check "V2"
      read "<MAGIC_NUMBER>\00"
      send "V2"
            +---------------> receive "V2"
                              check "V2"
                              send cpus,pagesize,option(MSG_TINIT)
      receive MSG_TINIT <-------+
      print "cpus=XXX"
      print "pagesize=XXX"
      understand option
      send port_array
               +--MSG_RINIT-> receive MSG_RINIT
                              understand port_array
                              send meta data(MSG_SENDMETA)
      receive MSG_SENDMETA <----+
      record meta data
                         (snip)
                              send a message to finish sending meta data
                                |                           (MSG_FINMETA)
      receive MSG_FINMETA <-----+
      read block
     --- start sending trace data on child processes ---

     --- When client finishes sending trace data ---
                              send MSG_CLOSE
      receive MSG_CLOSE <-------+
      close(socket fd)        close(socket fd)

By introducing the v2 protocol, after the client checks "tracecmd", the client
will send "V2\0<MAGIC_NUMBER>\00\0". This complex message is used when the
new client tries to connect to the old server. The new client wants to check
whether the reply message from the server is "V2" or not. However, the old
server does not respond to the client before receiving cpu numbers, page size,
and options. Each message is separated with "\0" in the old server, so the
client send "V2" as cpu numbers, "<MAGIC_NUMBER>" as page size, and "0" as
no options. On the other hands, the old server will understand the messages
as cpus=0, pagesize=<MAGIC_NUMBER>, and options=0, and then the server will
send the message "\0" as port numbers. Then, the message which the client
receives is not "V2" but "\0", so the client will reconnect to the old server
as the v1 protocol.

Changes in V2: Regacy porotocol support in order to keep backward compatibility
Changes in V3: Change the license of trace-msg.c to LGPL v2.1

Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
---
 Makefile       |    2 
 trace-cmd.h    |   11 +
 trace-listen.c |  133 +++++++----
 trace-msg.c    |  683 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 trace-msg.h    |   27 ++
 trace-output.c |    4 
 trace-record.c |   86 ++++++-
 7 files changed, 880 insertions(+), 66 deletions(-)
 create mode 100644 trace-msg.c
 create mode 100644 trace-msg.h

diff --git a/Makefile b/Makefile
index 1964949..054f53d 100644
--- a/Makefile
+++ b/Makefile
@@ -314,7 +314,7 @@ KERNEL_SHARK_OBJS = $(TRACE_VIEW_OBJS) $(TRACE_GRAPH_OBJS) $(TRACE_GUI_OBJS) \
 PEVENT_LIB_OBJS = event-parse.o trace-seq.o parse-filter.o parse-utils.o
 TCMD_LIB_OBJS = $(PEVENT_LIB_OBJS) trace-util.o trace-input.o trace-ftrace.o \
 			trace-output.o trace-recorder.o trace-restore.o trace-usage.o \
-			trace-blk-hack.o kbuffer-parse.o
+			trace-blk-hack.o kbuffer-parse.o trace-msg.o
 
 PLUGIN_OBJS = plugin_hrtimer.o plugin_kmem.o plugin_sched_switch.o \
 	plugin_mac80211.o plugin_jbd2.o plugin_function.o plugin_kvm.o \
diff --git a/trace-cmd.h b/trace-cmd.h
index cbbc6ed..a2958ac 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -248,6 +248,17 @@ void tracecmd_stop_recording(struct tracecmd_recorder *recorder);
 void tracecmd_stat_cpu(struct trace_seq *s, int cpu);
 long tracecmd_flush_recording(struct tracecmd_recorder *recorder);
 
+/* for clients */
+int tracecmd_msg_send_init_data(int fd);
+int tracecmd_msg_metadata_send(int fd, char *buf, int size);
+int tracecmd_msg_finish_sending_metadata(int fd);
+void tracecmd_msg_send_close_msg();
+
+/* for server */
+int tracecmd_msg_initial_setting(int fd, int *cpus, int *pagesize);
+int tracecmd_msg_send_port_array(int fd, int total_cpus, int *ports);
+int tracecmd_msg_collect_metadata(int ifd, int ofd);
+
 /* --- Plugin handling --- */
 extern struct plugin_option trace_ftrace_options[];
 
diff --git a/trace-listen.c b/trace-listen.c
index bf187c9..280b1af 100644
--- a/trace-listen.c
+++ b/trace-listen.c
@@ -33,6 +33,7 @@
 #include <errno.h>
 
 #include "trace-local.h"
+#include "trace-msg.h"
 
 #define MAX_OPTION_SIZE 4096
 
@@ -45,10 +46,10 @@ static FILE *logfp;
 
 static int debug;
 
-static int use_tcp;
-
 static int backlog = 5;
 
+static int proto_ver;
+
 #define  TEMP_FILE_STR "%s.%s:%s.cpu%d", output_file, host, port, cpu
 static char *get_temp_file(const char *host, const char *port, int cpu)
 {
@@ -112,10 +113,9 @@ static int process_option(char *option)
 	return 0;
 }
 
-static int done;
 static void finish(int sig)
 {
-	done = 1;
+	done = true;
 }
 
 #define LOG_BUF_SIZE 1024
@@ -144,7 +144,7 @@ static void __plog(const char *prefix, const char *fmt, va_list ap,
 	fprintf(fp, "%.*s", r, buf);
 }
 
-static void plog(const char *fmt, ...)
+void plog(const char *fmt, ...)
 {
 	va_list ap;
 
@@ -153,7 +153,7 @@ static void plog(const char *fmt, ...)
 	va_end(ap);
 }
 
-static void pdie(const char *fmt, ...)
+void pdie(const char *fmt, ...)
 {
 	va_list ap;
 	char *str = "";
@@ -324,56 +324,78 @@ static int communicate_with_client(int fd, int *cpus, int *pagesize)
 
 	*cpus = atoi(buf);
 
-	plog("cpus=%d\n", *cpus);
-	if (*cpus < 0)
-		return -1;
+	/* Is the client using the new protocol? */
+	if (!*cpus) {
+		if (memcmp(buf, "V2", 2) != 0) {
+			plog("Cannot handle the protocol %s", buf);
+			return -1;
+		}
 
-	/* next read the page size */
-	n = read_string(fd, buf, BUFSIZ);
-	if (n == BUFSIZ)
-		/** ERROR **/
-		return -1;
+		/* read the rest of dummy data, but not use */
+		read(fd, buf, sizeof(V2_MAGIC)+1);
 
-	*pagesize = atoi(buf);
+		proto_ver = V2_PROTOCOL;
 
-	plog("pagesize=%d\n", *pagesize);
-	if (*pagesize <= 0)
-		return -1;
+		/* Let the client know we use v2 protocol */
+		write(fd, "V2", 2);
 
-	/* Now the number of options */
-	n = read_string(fd, buf, BUFSIZ);
-	if (n == BUFSIZ)
-		/** ERROR **/
-		return -1;
+		/* read the CPU count, the page size, and options */
+		if (tracecmd_msg_initial_setting(fd, cpus, pagesize) < 0)
+			return -1;
+	} else {
+		/* The client is using the v1 protocol */
 
-	options = atoi(buf);
+		plog("cpus=%d\n", *cpus);
+		if (*cpus < 0)
+			return -1;
 
-	for (i = 0; i < options; i++) {
-		/* next is the size of the options */
+		/* next read the page size */
 		n = read_string(fd, buf, BUFSIZ);
 		if (n == BUFSIZ)
 			/** ERROR **/
 			return -1;
-		size = atoi(buf);
-		/* prevent a client from killing us */
-		if (size > MAX_OPTION_SIZE)
+
+		*pagesize = atoi(buf);
+
+		plog("pagesize=%d\n", *pagesize);
+		if (*pagesize <= 0)
 			return -1;
-		option = malloc_or_die(size);
-		do {
-			t = size;
-			s = 0;
-			s = read(fd, option+s, t);
-			if (s <= 0)
-				return -1;
-			t -= s;
-			s = size - t;
-		} while (t);
 
-		s = process_option(option);
-		free(option);
-		/* do we understand this option? */
-		if (!s)
+		/* Now the number of options */
+		n = read_string(fd, buf, BUFSIZ);
+		if (n == BUFSIZ)
+			/** ERROR **/
 			return -1;
+
+		options = atoi(buf);
+
+		for (i = 0; i < options; i++) {
+			/* next is the size of the options */
+			n = read_string(fd, buf, BUFSIZ);
+			if (n == BUFSIZ)
+				/** ERROR **/
+				return -1;
+			size = atoi(buf);
+			/* prevent a client from killing us */
+			if (size > MAX_OPTION_SIZE)
+				return -1;
+			option = malloc_or_die(size);
+			do {
+				t = size;
+				s = 0;
+				s = read(fd, option+s, t);
+				if (s <= 0)
+					return -1;
+				t -= s;
+				s = size - t;
+			} while (t);
+
+			s = process_option(option);
+			free(option);
+			/* do we understand this option? */
+			if (!s)
+				return -1;
+		}
 	}
 
 	if (use_tcp)
@@ -442,14 +464,20 @@ static int *create_all_readers(int cpus, const char *node, const char *port,
 		start_port = udp_port + 1;
 	}
 
-	/* send the client a comma deliminated set of port numbers */
-	for (cpu = 0; cpu < cpus; cpu++) {
-		snprintf(buf, BUFSIZ, "%s%d",
-			 cpu ? "," : "", port_array[cpu]);
-		write(fd, buf, strlen(buf));
+	if (proto_ver == V2_PROTOCOL) {
+		/* send set of port numbers to the client */
+		if (tracecmd_msg_send_port_array(fd, cpus, port_array) < 0)
+			goto out_free;
+	} else {
+		/* send the client a comma deliminated set of port numbers */
+		for (cpu = 0; cpu < cpus; cpu++) {
+			snprintf(buf, BUFSIZ, "%s%d",
+				 cpu ? "," : "", port_array[cpu]);
+			write(fd, buf, strlen(buf));
+		}
+		/* end with null terminator */
+		write(fd, "\0", 1);
 	}
-	/* end with null terminator */
-	write(fd, "\0", 1);
 
 	return pid_array;
 
@@ -528,7 +556,10 @@ static void process_client(const char *node, const char *port, int fd)
 		return;
 
 	/* Now we are ready to start reading data from the client */
-	collect_metadata_from_client(fd, ofd);
+	if (proto_ver == V2_PROTOCOL)
+		tracecmd_msg_collect_metadata(fd, ofd);
+	else
+		collect_metadata_from_client(fd, ofd);
 
 	/* wait a little to let our readers finish reading */
 	sleep(1);
diff --git a/trace-msg.c b/trace-msg.c
new file mode 100644
index 0000000..2551617
--- /dev/null
+++ b/trace-msg.c
@@ -0,0 +1,683 @@
+/*
+ * trace-msg.c : define message protocol for communication between clients and
+ *               a server
+ *
+ * Copyright (C) 2013 Hitachi, Ltd.
+ * Created by Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * 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 Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <errno.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/types.h>
+#include <linux/types.h>
+
+#include "trace-cmd-local.h"
+#include "trace-msg.h"
+
+typedef __u32 u32;
+typedef __be32 be32;
+
+#define TRACECMD_MSG_MAX_LEN		BUFSIZ
+
+					/* size + cmd */
+#define TRACECMD_MSG_HDR_LEN		((sizeof(be32)) + (sizeof(be32)))
+
+					/* + size of the metadata */
+#define TRACECMD_MSG_META_MIN_LEN	\
+				((TRACECMD_MSG_HDR_LEN) + (sizeof(be32)))
+
+					/* - header size for error msg */
+#define TRACECMD_MSG_META_MAX_LEN	\
+((TRACECMD_MSG_MAX_LEN) - (TRACECMD_MSG_META_MIN_LEN) - TRACECMD_MSG_HDR_LEN)
+
+					/* size + opt_cmd + size of str */
+#define TRACECMD_OPT_MIN_LEN		\
+			((sizeof(be32)) + (sizeof(be32)) +(sizeof(be32)))
+
+
+#define CPU_MAX				256
+
+/* for both client and server */
+bool use_tcp;
+int cpu_count;
+
+/* for client */
+static int psfd;
+unsigned int page_size;
+int *client_ports;
+bool send_metadata;
+
+/* for server */
+static int *port_array;
+bool done;
+
+struct tracecmd_msg_str {
+	be32 size;
+	char *buf;
+} __attribute__((packed));
+
+struct tracecmd_msg_opt {
+	be32 size;
+	be32 opt_cmd;
+	struct tracecmd_msg_str str;
+};
+
+struct tracecmd_msg_tinit {
+	be32 cpus;
+	be32 page_size;
+	be32 opt_num;
+	struct tracecmd_msg_opt *opt;
+} __attribute__((packed));
+
+struct tracecmd_msg_rinit {
+	be32 cpus;
+	be32 port_array[CPU_MAX];
+} __attribute__((packed));
+
+struct tracecmd_msg_meta {
+	struct tracecmd_msg_str str;
+};
+
+struct tracecmd_msg_error {
+	be32 size;
+	be32 cmd;
+	union {
+		struct tracecmd_msg_tinit tinit;
+		struct tracecmd_msg_rinit rinit;
+		struct tracecmd_msg_meta meta;
+	} data;
+} __attribute__((packed));
+
+enum tracecmd_msg_cmd {
+	MSG_CLOSE	= 1,
+	MSG_TINIT	= 4,
+	MSG_RINIT	= 5,
+	MSG_SENDMETA	= 6,
+	MSG_FINMETA	= 7,
+};
+
+struct tracecmd_msg {
+	be32 size;
+	be32 cmd;
+	union {
+		struct tracecmd_msg_tinit tinit;
+		struct tracecmd_msg_rinit rinit;
+		struct tracecmd_msg_meta meta;
+		struct tracecmd_msg_error err;
+	} data;
+} __attribute__((packed));
+
+struct tracecmd_msg *errmsg;
+
+static ssize_t msg_do_write_check(int fd, struct tracecmd_msg *msg)
+{
+	return __do_write_check(fd, msg, ntohl(msg->size));
+}
+
+static struct tracecmd_msg *tracecmd_msg_alloc(u32 size)
+{
+	size += TRACECMD_MSG_HDR_LEN;
+	return malloc(size);
+}
+
+static void tracecmd_msg_init(u32 cmd, u32 size, struct tracecmd_msg *msg)
+{
+	size += TRACECMD_MSG_HDR_LEN;
+	memset(msg, 0, size);
+	msg->size = htonl(size);
+	msg->cmd = htonl(cmd);
+}
+
+static void bufcpy(void *dest, u32 offset, const void *buf, u32 buflen)
+{
+	memcpy(dest+offset, buf, buflen);
+}
+
+enum msg_opt_command {
+	MSGOPT_USETCP = 1,
+};
+
+static struct tracecmd_msg_opt *tracecmd_msg_opt_alloc(u32 len)
+{
+	len += TRACECMD_OPT_MIN_LEN;
+	return malloc(len);
+}
+
+static void make_option(int opt_cmd, const char *buf,
+		       struct tracecmd_msg_opt *opt)
+{
+	u32 buflen = 0;
+	u32 size = TRACECMD_OPT_MIN_LEN;
+
+	if (buf) {
+		buflen = strlen(buf);
+		size += buflen;
+	}
+
+	opt->size = htonl(size);
+	opt->opt_cmd = htonl(opt_cmd);
+	opt->str.size = htonl(buflen);
+
+	if (buf)
+		bufcpy(opt, TRACECMD_OPT_MIN_LEN, buf, buflen);
+}
+
+static int add_options_to_tinit(u32 len, struct tracecmd_msg *msg)
+{
+	struct tracecmd_msg_opt *opt;
+	int offset = offsetof(struct tracecmd_msg, data.tinit.opt);
+
+	if (use_tcp) {
+		opt = tracecmd_msg_opt_alloc(0);
+		if (!opt)
+			return -ENOMEM;
+
+		make_option(MSGOPT_USETCP, NULL, opt);
+		/* add option */
+		bufcpy(msg, offset, opt, ntohl(opt->size));
+		free(opt);
+	}
+
+	return 0;
+}
+
+static int make_tinit(u32 len, struct tracecmd_msg *msg)
+{
+	int opt_num = 0;
+	int ret = 0;
+
+	if (use_tcp)
+		opt_num++;
+
+	if (opt_num) {
+		ret = add_options_to_tinit(len, msg);
+		if (ret < 0)
+			return ret;
+	}
+
+	msg->data.tinit.cpus = htonl(cpu_count);
+	msg->data.tinit.page_size = htonl(page_size);
+	msg->data.tinit.opt_num = htonl(opt_num);
+
+	return 0;
+}
+
+static int make_rinit(struct tracecmd_msg *msg)
+{
+	int i;
+	u32 offset = TRACECMD_MSG_HDR_LEN;
+	be32 port;
+
+	msg->data.rinit.cpus = htonl(cpu_count);
+
+	for (i = 0; i < cpu_count; i++) {
+		/* + rrqports->cpus or rrqports->port_array[i] */
+		offset += sizeof(be32);
+		port = htonl(port_array[i]);
+		bufcpy(msg, offset, &port, sizeof(be32) * cpu_count);
+	}
+
+	return 0;
+}
+
+static u32 tracecmd_msg_get_body_length(u32 cmd)
+{
+	struct tracecmd_msg *msg;
+	u32 len = 0;
+
+	switch (cmd) {
+	case MSG_TINIT:
+		len = sizeof(msg->data.tinit.cpus)
+		      + sizeof(msg->data.tinit.page_size)
+		      + sizeof(msg->data.tinit.opt_num);
+
+		/*
+		 * If we are using IPV4 and our page size is greater than
+		 * or equal to 64K, we need to punt and use TCP. :-(
+		 */
+
+		/* TODO, test for ipv4 */
+		if (page_size >= UDP_MAX_PACKET) {
+		        warning("page size too big for UDP using TCP "
+				"in live read");
+		        use_tcp = true;
+		}
+
+		if (use_tcp)
+			len += TRACECMD_OPT_MIN_LEN;
+
+		return len;
+	case MSG_RINIT:
+		return sizeof(msg->data.rinit.cpus)
+		       + sizeof(msg->data.rinit.port_array);
+	case MSG_SENDMETA:
+		return TRACECMD_MSG_MAX_LEN - TRACECMD_MSG_HDR_LEN;
+	case MSG_CLOSE:
+	case MSG_FINMETA:
+		break;
+	}
+
+	return 0;
+}
+
+static int tracecmd_msg_make_body(u32 cmd, u32 len, struct tracecmd_msg *msg)
+{
+	switch (cmd) {
+	case MSG_TINIT:
+		return make_tinit(len, msg);
+	case MSG_RINIT:
+		return make_rinit(msg);
+	case MSG_CLOSE:
+	case MSG_SENDMETA: /* meta data is not stored here. */
+	case MSG_FINMETA:
+		break;
+	}
+
+	return 0;
+}
+
+static int tracecmd_msg_create(u32 cmd, struct tracecmd_msg **msg)
+{
+	u32 len = 0;
+	int ret = 0;
+
+	len = tracecmd_msg_get_body_length(cmd);
+	if (len > (TRACECMD_MSG_MAX_LEN - TRACECMD_MSG_HDR_LEN)) {
+		plog("Exceed maximum message size cmd=%d\n", cmd);
+		return -EINVAL;
+	}
+
+	*msg = tracecmd_msg_alloc(len);
+	if (!*msg)
+		return -ENOMEM;
+	tracecmd_msg_init(cmd, len, *msg);
+
+	ret = tracecmd_msg_make_body(cmd, len, *msg);
+	if (ret < 0)
+		free(*msg);
+
+	return ret;
+}
+
+static int tracecmd_msg_send(int fd, u32 cmd)
+{
+	struct tracecmd_msg *msg = NULL;
+	int ret = 0;
+
+	if (cmd > MSG_FINMETA) {
+		plog("Unsupported command: %d\n", cmd);
+		return -EINVAL;
+	}
+
+	ret = tracecmd_msg_create(cmd, &msg);
+	if (ret < 0)
+		return ret;
+
+	ret = msg_do_write_check(fd, msg);
+	if (ret < 0) {
+		free(msg);
+		return -ECOMM;
+	}
+
+	return 0;
+}
+
+static int tracecmd_msg_read_extra(int fd, char *buf, u32 size, int *n)
+{
+	int r = 0;
+
+	do {
+		r = read(fd, buf+*n, size);
+		if (r < 0) {
+			if (errno == EINTR)
+				continue;
+			return -errno;
+		} else if (!r)
+			return -ENOTCONN;
+		size -= r;
+		*n += r;
+	} while (size);
+
+	return 0;
+}
+
+/*
+ * Read header information of msg first, then read all data
+ */
+static int tracecmd_msg_recv(int fd, char *buf)
+{
+	struct tracecmd_msg *msg;
+	u32 size = 0;
+	int n = 0;
+	int ret;
+
+	ret = tracecmd_msg_read_extra(fd, buf, TRACECMD_MSG_HDR_LEN, &n);
+	if (ret < 0)
+		return ret;
+
+	msg = (struct tracecmd_msg *)buf;
+	size = ntohl(msg->size);
+	if (size > TRACECMD_MSG_MAX_LEN)
+		/* too big */
+		goto error;
+	else if (size < TRACECMD_MSG_HDR_LEN)
+		/* too small */
+		goto error;
+	else if (size > TRACECMD_MSG_HDR_LEN) {
+		size -= TRACECMD_MSG_HDR_LEN;
+		return tracecmd_msg_read_extra(fd, buf, size, &n);
+	}
+
+	return 0;
+error:
+	plog("Receive an invalid message(size=%d)\n", size);
+	return -ENOMSG;
+}
+
+static void *tracecmd_msg_buf_access(struct tracecmd_msg *msg, int offset)
+{
+	return (void *)msg + offset;
+}
+
+static int tracecmd_msg_wait_for_msg(int fd, struct tracecmd_msg **msg)
+{
+	char msg_tmp[TRACECMD_MSG_MAX_LEN];
+	u32 cmd;
+	int ret;
+
+	ret = tracecmd_msg_recv(fd, msg_tmp);
+	if (ret < 0)
+		return ret;
+
+	*msg = (struct tracecmd_msg *)msg_tmp;
+	cmd = ntohl((*msg)->cmd);
+	if (cmd == MSG_CLOSE)
+		return -ECONNABORTED;
+
+	return 0;
+}
+
+static int tracecmd_msg_send_and_wait_for_msg(int fd, u32 cmd, struct tracecmd_msg **msg)
+{
+ 	int ret;
+ 
+	ret = tracecmd_msg_send(fd, cmd);
+ 	if (ret < 0)
+		return ret;
+ 
+	ret = tracecmd_msg_wait_for_msg(fd, msg);
+ 	if (ret < 0) 
+ 		return ret;
+ 
+	return 0;
+}
+
+int tracecmd_msg_send_init_data(int fd)
+{
+	struct tracecmd_msg *msg;
+	int i, cpus;
+	int ret;
+
+	ret = tracecmd_msg_send_and_wait_for_msg(fd, MSG_TINIT, &msg);
+	if (ret < 0)
+		return ret;
+
+	cpus = ntohl(msg->data.rinit.cpus);
+	client_ports = malloc_or_die(sizeof(int) * cpus);
+	for (i = 0; i < cpus; i++)
+		client_ports[i] = ntohl(msg->data.rinit.port_array[i]);
+
+	/* Next, send meta data */
+	send_metadata = true;
+
+	return 0;
+}
+
+static bool process_option(struct tracecmd_msg_opt *opt)
+{
+	/* currently the only option we have is to us TCP */
+	if (ntohl(opt->opt_cmd) == MSGOPT_USETCP) {
+		use_tcp = true;
+		return true;
+	}
+	return false;
+}
+
+static void error_operation_for_server(struct tracecmd_msg *msg)
+{
+	u32 cmd;
+
+	cmd = ntohl(msg->cmd);
+
+	warning("Message: cmd=%d size=%d\n", cmd, ntohl(msg->size));
+}
+
+#define MAX_OPTION_SIZE 4096
+
+int tracecmd_msg_initial_setting(int fd, int *cpus, int *pagesize)
+{
+	struct tracecmd_msg *msg;
+	struct tracecmd_msg_opt *opt;
+	char buf[TRACECMD_MSG_MAX_LEN];
+	int offset = offsetof(struct tracecmd_msg, data.tinit.opt);
+	int options, i, s;
+	int ret;
+	u32 size = 0;
+	u32 cmd;
+
+	ret = tracecmd_msg_recv(fd, buf);
+	if (ret < 0)
+		return ret;
+
+	msg = (struct tracecmd_msg *)buf;
+	cmd = ntohl(msg->cmd);
+	if (cmd != MSG_TINIT) {
+		ret = -EINVAL;
+		goto error;
+	}
+
+	*cpus = ntohl(msg->data.tinit.cpus);
+	plog("cpus=%d\n", *cpus);
+	if (*cpus < 0) {
+		ret = -EINVAL;
+		goto error;
+	}
+	
+	*pagesize = ntohl(msg->data.tinit.page_size);
+	plog("pagesize=%d\n", *pagesize);
+	if (*pagesize <= 0) {
+		ret = -EINVAL;
+		goto error;
+	}
+
+	options = ntohl(msg->data.tinit.opt_num);
+	for (i = 0; i < options; i++) {
+		offset += size;
+		opt = tracecmd_msg_buf_access(msg, offset);
+		size = ntohl(opt->size);
+		/* prevent a client from killing us */
+		if (size > MAX_OPTION_SIZE) {
+			plog("Exceed MAX_OPTION_SIZE\n");
+			ret = -EINVAL;
+			goto error;
+		}
+		s = process_option(opt);
+		/* do we understand this option? */
+		if (!s) {
+			plog("Cannot understand(%d:%d:%d)\n",
+			     i, ntohl(opt->size), ntohl(opt->opt_cmd));
+			ret = -EINVAL;
+			goto error;
+		}
+	}
+
+	return 0;
+
+error:
+	error_operation_for_server(msg);
+	return ret;
+}
+
+int tracecmd_msg_send_port_array(int fd, int total_cpus, int *ports)
+{
+	int ret;
+
+	cpu_count = total_cpus;
+	port_array = ports;
+
+	ret = tracecmd_msg_send(fd, MSG_RINIT);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+void tracecmd_msg_send_close_msg()
+{
+	tracecmd_msg_send(psfd, MSG_CLOSE);
+}
+
+static void make_meta(const char *buf, int buflen, struct tracecmd_msg *msg)
+{
+	int offset = offsetof(struct tracecmd_msg, data.meta.str.buf);
+
+	msg->data.meta.str.size = htonl(buflen);
+	bufcpy(msg, offset, buf, buflen);
+}
+
+int tracecmd_msg_metadata_send(int fd, char *buf, int size)
+{
+	struct tracecmd_msg *msg;
+	int n, len;
+	int ret;
+	int count = 0;
+
+	ret = tracecmd_msg_create(MSG_SENDMETA, &msg);
+	if (ret < 0)
+		return ret;
+
+	n = size;
+	do {
+		if (n > TRACECMD_MSG_META_MAX_LEN) {
+			make_meta(buf+count, TRACECMD_MSG_META_MAX_LEN, msg);
+			n -= TRACECMD_MSG_META_MAX_LEN;
+			count += TRACECMD_MSG_META_MAX_LEN;
+		} else {
+			make_meta(buf+count, n, msg);
+			/*
+			 * TRACECMD_MSG_META_MAX_LEN is stored in msg->size,
+			 * so update the size to the correct value.
+			 */
+			len = TRACECMD_MSG_META_MIN_LEN + n;
+			msg->size = htonl(len);
+			n = 0;
+		}
+
+		ret = msg_do_write_check(fd, msg);
+		if (ret < 0)
+			return ret;
+	} while (n);
+
+	return 0;
+}
+
+int tracecmd_msg_finish_sending_metadata(int fd)
+{
+	int ret;
+
+	ret = tracecmd_msg_send(fd, MSG_FINMETA);
+	if (ret < 0)
+		return ret;
+
+	/* psfd will be used for closing */
+	psfd = fd;
+	return 0;
+}
+
+int tracecmd_msg_collect_metadata(int ifd, int ofd)
+{
+	struct tracecmd_msg *msg;
+	char buf[TRACECMD_MSG_MAX_LEN];
+	u32 s, t, n, cmd;
+	int offset = TRACECMD_MSG_META_MIN_LEN;
+	int ret;
+
+	do {
+		ret = tracecmd_msg_recv(ifd, buf);
+		if (ret < 0) {
+			warning("reading client");
+			return ret;
+		}
+
+		msg = (struct tracecmd_msg *)buf;
+		cmd = ntohl(msg->cmd);
+		if (cmd == MSG_FINMETA) {
+			/* Finish receiving meta data */
+			break;
+		} else if (cmd != MSG_SENDMETA)
+			goto error;
+
+		n = ntohl(msg->data.meta.str.size);
+		t = n;
+		s = 0;
+		do {
+			s = write(ofd, buf+s+offset, t);
+			if (s < 0) {
+				if (errno == EINTR)
+					continue;
+				warning("writing to file");
+				return -errno;
+			}
+			t -= s;
+			s = n - t;
+		} while (t);
+	} while (cmd == MSG_SENDMETA);
+
+	/* check the finish message of the client */
+	while(!done) {
+		ret = tracecmd_msg_recv(ifd, buf);
+		if (ret < 0) {
+			warning("reading client");
+			return ret;
+		}
+
+		msg = (struct tracecmd_msg *)buf;
+		cmd = ntohl(msg->cmd);
+		if (cmd == MSG_CLOSE)
+			/* Finish this connection */
+			break;
+		else {
+			warning("Not accept the message %d", ntohl(msg->cmd));
+			ret = -EINVAL;
+			goto error;
+		}
+	}
+
+	return 0;
+
+error:
+	error_operation_for_server(msg);
+	return ret;
+}
diff --git a/trace-msg.h b/trace-msg.h
new file mode 100644
index 0000000..b23e72b
--- /dev/null
+++ b/trace-msg.h
@@ -0,0 +1,27 @@
+#ifndef _TRACE_MSG_H_
+#define _TRACE_MSG_H_
+
+#include <stdbool.h>
+
+#define UDP_MAX_PACKET	(65536 - 20)
+#define V2_MAGIC	"677768\0"
+
+#define V1_PROTOCOL	1
+#define V2_PROTOCOL	2
+
+/* for both client and server */
+extern bool use_tcp;
+extern int cpu_count;
+
+/* for client */
+extern unsigned int page_size;
+extern int *client_ports;
+extern bool send_metadata;
+
+/* for server */
+extern bool done;
+
+void plog(const char *fmt, ...);
+void pdie(const char *fmt, ...);
+
+#endif /* _TRACE_MSG_H_ */
diff --git a/trace-output.c b/trace-output.c
index bdb478d..6e1298b 100644
--- a/trace-output.c
+++ b/trace-output.c
@@ -36,6 +36,7 @@
 #include <glob.h>
 
 #include "trace-cmd-local.h"
+#include "trace-msg.h"
 #include "version.h"
 
 /* We can't depend on the host size for size_t, all must be 64 bit */
@@ -80,6 +81,9 @@ struct list_event_system {
 static stsize_t
 do_write_check(struct tracecmd_output *handle, void *data, tsize_t size)
 {
+	if (send_metadata)
+		return tracecmd_msg_metadata_send(handle->fd, data, size);
+
 	return __do_write_check(handle->fd, data, size);
 }
 
diff --git a/trace-record.c b/trace-record.c
index 0199627..ebfe6c0 100644
--- a/trace-record.c
+++ b/trace-record.c
@@ -45,6 +45,7 @@
 #include <errno.h>
 
 #include "trace-local.h"
+#include "trace-msg.h"
 
 #define _STR(x) #x
 #define STR(x) _STR(x)
@@ -59,29 +60,21 @@
 #define STAMP		"stamp"
 #define FUNC_STACK_TRACE "func_stack_trace"
 
-#define UDP_MAX_PACKET (65536 - 20)
-
 static int tracing_on_init_val;
 
 static int rt_prio;
 
-static int use_tcp;
-
-static unsigned int page_size;
-
 static int buffer_size;
 
 static const char *output_file = "trace.dat";
 
 static int latency;
 static int sleep_time = 1000;
-static int cpu_count;
 static int recorder_threads;
 static int *pids;
 static int buffers;
 
 static char *host;
-static int *client_ports;
 static int sfd;
 
 /* Max size to let a per cpu file get */
@@ -99,6 +92,8 @@ static unsigned recorder_flags;
 /* Try a few times to get an accurate date */
 static int date2ts_tries = 5;
 
+static int proto_ver = V2_PROTOCOL;
+
 struct func_list {
 	struct func_list *next;
 	const char *func;
@@ -1607,20 +1602,26 @@ static int create_recorder(struct buffer_instance *instance, int cpu, int extrac
 	exit(0);
 }
 
-static void communicate_with_listener(int fd)
+static void check_first_msg_from_server(int fd)
 {
 	char buf[BUFSIZ];
-	ssize_t n;
-	int cpu, i;
 
-	n = read(fd, buf, 8);
+	read(fd, buf, 8);
 
 	/* Make sure the server is the tracecmd server */
 	if (memcmp(buf, "tracecmd", 8) != 0)
 		die("server not tracecmd server");
+}
 
-	/* write the number of CPUs we have (in ASCII) */
+static void communicate_with_listener_v1(int fd)
+{
+	char buf[BUFSIZ];
+	ssize_t n;
+	int cpu, i;
+
+	check_first_msg_from_server(fd);
 
+	/* write the number of CPUs we have (in ASCII) */
 	sprintf(buf, "%d", cpu_count);
 
 	/* include \0 */
@@ -1675,6 +1676,46 @@ static void communicate_with_listener(int fd)
 	}
 }
 
+static void communicate_with_listener_v2(int fd)
+{
+	if (tracecmd_msg_send_init_data(fd) < 0)
+		die("Cannot communicate with server");
+}
+
+static void check_protocol_version(int fd)
+{
+	char buf[BUFSIZ];
+
+	check_first_msg_from_server(fd);
+
+	/*
+	 * Write the protocol version, the magic number, and the dummy
+	 * option(0) (in ASCII). The client understands whether the client
+	 * uses the v2 protocol or not by checking a reply message from the
+	 * server. If the message is "V2", the server uses v2 protocol. On the
+	 * other hands, if the message is just number strings, the server
+	 * returned port numbers. So, in that time, the client understands the
+	 * server uses the v1 protocol. However, the old server tells the
+	 * client port numbers after reading cpu_count, page_size, and option.
+	 * So, we add the dummy number (the magic number and 0 option) to the
+	 * first client message.
+	 */
+	write(fd, "V2\0"V2_MAGIC"0", sizeof(V2_MAGIC)+4);
+
+	/* read a reply message */
+	read(fd, buf, BUFSIZ);
+
+	if (!buf[0]) {
+		/* the server uses the v1 protocol, so we'll use it */
+		proto_ver = V1_PROTOCOL;
+		plog("Use the v1 protocol\n");
+	} else {
+		if (memcmp(buf, "V2", 2) != 0)
+			die("Cannot handle the protocol %s", buf);
+		/* OK, let's use v2 protocol */
+	}
+}
+
 static void setup_network(void)
 {
 	struct tracecmd_output *handle;
@@ -1703,6 +1744,7 @@ static void setup_network(void)
 	hints.ai_family = AF_UNSPEC;
 	hints.ai_socktype = SOCK_STREAM;
 
+again:
 	s = getaddrinfo(server, port, &hints, &result);
 	if (s != 0)
 		die("getaddrinfo: %s", gai_strerror(s));
@@ -1723,16 +1765,32 @@ static void setup_network(void)
 
 	freeaddrinfo(result);
 
-	communicate_with_listener(sfd);
+	if (proto_ver == V2_PROTOCOL) {
+		check_protocol_version(sfd);
+		if (proto_ver == V1_PROTOCOL) {
+			/* reconnect to the server for using the v1 protocol */
+			close(sfd);
+			goto again;
+		}
+		communicate_with_listener_v2(sfd);
+	}
+
+	if (proto_ver == V1_PROTOCOL)
+		communicate_with_listener_v1(sfd);
 
 	/* Now create the handle through this socket */
 	handle = tracecmd_create_init_fd_glob(sfd, listed_events);
 
+	if (proto_ver == V2_PROTOCOL)
+		tracecmd_msg_finish_sending_metadata(sfd);
+
 	/* OK, we are all set, let'r rip! */
 }
 
 static void finish_network(void)
 {
+	if (proto_ver == V2_PROTOCOL)
+		tracecmd_msg_send_close_msg();
 	close(sfd);
 	free(host);
 }

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