trace-cmd listen: Update the V2 protocol to handle old and new
Change the protocol slightly where V1 will fail right away without creating
a blank trace.dat file by appending '-1' to the V2 name. The old trace-cmd
listen will see that as a negative CPU count and bail.
Also change the hand shake a bit such that if we go to a V3, a V2 server
could just let the newer trace-cmd client know what version it can support.
Here's the update:
<server> <client>
listen to socket fd
connect to socket fd
accept the client
send "tracecmd"
+------------> receive "tracecmd"
check "tracecmd"
* send "-1V2\0"
* try_again:
* receive "-1V2" <------------+
* check "-1V2"
* if (!"-1V2") {
* if (memcmp("-1V",3))
* error();
* send "V2\0"
* goto try_again;
* }
* send "V2"
* +---------------> receive "V2"
* check "V2"
* send "<MAGIC_NUMBER>\00" as the v2 protocol
read "<MAGIC_NUMBER>\00"
* send "OK"
* +---------------> receive "OK"
* check "OK"
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)
The '*' represents what was updated.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/trace-listen.c b/trace-listen.c
index 77df7c3..16375f8 100644
--- a/trace-listen.c
+++ b/trace-listen.c
@@ -317,15 +317,18 @@
static int communicate_with_client(int fd, int *cpus, int *pagesize)
{
+ char *last_proto = NULL;
char buf[BUFSIZ];
char *option;
int options;
int size;
int n, s, t, i;
+ int ret = -EINVAL;
/* Let the client know what we are */
write(fd, "tracecmd", 8);
+ try_again:
/* read back the CPU count */
n = read_string(fd, buf, BUFSIZ);
if (n == BUFSIZ)
@@ -335,41 +338,66 @@
*cpus = atoi(buf);
/* Is the client using the new protocol? */
- if (!*cpus) {
- if (memcmp(buf, "V2", 2) != 0) {
- plog("Cannot handle the protocol %s", buf);
- return -EINVAL;
+ if (*cpus == -1) {
+ if (memcmp(buf, V2_CPU, n) != 0) {
+ /* If it did not send a version, then bail */
+ if (memcmp(buf, "-1V", 3)) {
+ plog("Unknown string %s\n", buf);
+ goto out;
+ }
+ /* Skip "-1" */
+ plog("Cannot handle the protocol %s\n", buf+2);
+
+ /* If it returned the same command as last time, bail! */
+ if (last_proto && strncmp(last_proto, buf, n) == 0) {
+ plog("Repeat of version %s sent\n", last_proto);
+ goto out;
+ }
+ free(last_proto);
+ last_proto = malloc(n + 1);
+ if (last_proto) {
+ memcpy(last_proto, buf, n);
+ last_proto[n] = 0;
+ }
+ /* Return the highest protocol we can use */
+ write(fd, "V2", 3);
+ goto try_again;
}
- /* read the rest of dummy data, but not use */
- read(fd, buf, sizeof(V2_MAGIC)+1);
+ /* Let the client know we use v2 protocol */
+ write(fd, "V2", 3);
+
+ /* read the rest of dummy data */
+ n = read(fd, buf, sizeof(V2_MAGIC));
+ if (memcmp(buf, V2_MAGIC, n) != 0)
+ goto out;
+
+ /* We're off! */
+ write(fd, "OK", 2);
proto_ver = V2_PROTOCOL;
- /* Let the client know we use v2 protocol */
- write(fd, "V2", 2);
-
/* read the CPU count, the page size, and options */
if (tracecmd_msg_initial_setting(fd, cpus, pagesize) < 0)
- return -EINVAL;
+ goto out;
} else {
/* The client is using the v1 protocol */
plog("cpus=%d\n", *cpus);
if (*cpus < 0)
- return -EINVAL;
+ goto out;
/* next read the page size */
n = read_string(fd, buf, BUFSIZ);
if (n == BUFSIZ)
/** ERROR **/
- return -EINVAL;
+ goto out;
*pagesize = atoi(buf);
plog("pagesize=%d\n", *pagesize);
if (*pagesize <= 0)
- return -EINVAL;
+ goto out;
/* Now the number of options */
n = read_string(fd, buf, BUFSIZ);
@@ -384,20 +412,24 @@
n = read_string(fd, buf, BUFSIZ);
if (n == BUFSIZ)
/** ERROR **/
- return -EINVAL;
+ goto out;
size = atoi(buf);
/* prevent a client from killing us */
if (size > MAX_OPTION_SIZE)
- return -EINVAL;
+ goto out;
+
+ ret = -ENOMEM;
option = malloc(size);
if (!option)
- return -ENOMEM;
+ goto out;
+
+ ret = -EIO;
do {
t = size;
s = 0;
s = read(fd, option+s, t);
if (s <= 0)
- return -EIO;
+ goto out;
t -= s;
s = size - t;
} while (t);
@@ -405,15 +437,20 @@
s = process_option(option);
free(option);
/* do we understand this option? */
+ ret = -EINVAL;
if (!s)
- return -EINVAL;
+ goto out;
}
}
if (use_tcp)
plog("Using TCP for live connection\n");
- return 0;
+ ret = 0;
+ out:
+ free(last_proto);
+
+ return ret;
}
static int create_client_file(const char *node, const char *port)
diff --git a/trace-msg.h b/trace-msg.h
index b23e72b..0cc972c 100644
--- a/trace-msg.h
+++ b/trace-msg.h
@@ -5,6 +5,7 @@
#define UDP_MAX_PACKET (65536 - 20)
#define V2_MAGIC "677768\0"
+#define V2_CPU "-1V2"
#define V1_PROTOCOL 1
#define V2_PROTOCOL 2
diff --git a/trace-record.c b/trace-record.c
index b6f58f9..4706f90 100644
--- a/trace-record.c
+++ b/trace-record.c
@@ -2699,6 +2699,7 @@
static void check_protocol_version(int fd)
{
char buf[BUFSIZ];
+ int n;
check_first_msg_from_server(fd);
@@ -2714,19 +2715,28 @@
* 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);
+ write(fd, V2_CPU, sizeof(V2_CPU));
/* read a reply message */
- read(fd, buf, BUFSIZ);
+ n = read(fd, buf, BUFSIZ);
- if (!buf[0]) {
+ if (n < 0 || !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)
+ if (memcmp(buf, "V2", n) != 0)
die("Cannot handle the protocol %s", buf);
/* OK, let's use v2 protocol */
+ write(fd, V2_MAGIC, sizeof(V2_MAGIC));
+
+ n = read(fd, buf, BUFSIZ - 1);
+ if (n != 2 || memcmp(buf, "OK", 2) != 0) {
+ if (n < 0)
+ n = 0;
+ buf[n] = 0;
+ die("Cannot handle the protocol %s", buf);
+ }
}
}
