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io: get rid of bounce buffering in websock write path 

Currently most outbound I/O on the websock channel gets copied into the
rawoutput buffer, and then immediately copied again into the encoutput
buffer, with a header prepended. Now that qio_channel_websock_encode
accepts a struct iovec, we can trivially remove this bounce buffering
and write directly to encoutput.

In doing so, we also now correctly validate the encoutput size against
the QIO_CHANNEL_WEBSOCK_MAX_BUFFER limit.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange 2017-10-09 16:54:07 +01:00
parent fb74e59039
commit 8dfd5f9651
2 changed files with 28 additions and 37 deletions
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1
include/io/channel-websock.h
View File

@ -59,7 +59,6 @@ struct QIOChannelWebsock {
Buffer encinput;
Buffer encoutput;
Buffer rawinput;
Buffer rawoutput;
size_t payload_remain;
size_t pong_remain;
QIOChannelWebsockMask mask;

64
io/channel-websock.c
View File

@ -24,6 +24,7 @@
#include "io/channel-websock.h"
#include "crypto/hash.h"
#include "trace.h"
#include "qemu/iov.h"
#include <time.h>
@ -633,19 +634,22 @@ static ssize_t qio_channel_websock_write_wire(QIOChannelWebsock *, Error **);
static void qio_channel_websock_write_close(QIOChannelWebsock *ioc,
uint16_t code, const char *reason)
{
struct iovec iov;
buffer_reserve(&ioc->rawoutput, 2 + (reason ? strlen(reason) : 0));
*(uint16_t *)(ioc->rawoutput.buffer + ioc->rawoutput.offset) =
cpu_to_be16(code);
ioc->rawoutput.offset += 2;
struct iovec iov[2] = {
{ .iov_base = &code, .iov_len = sizeof(code) },
};
size_t niov = 1;
size_t size = iov[0].iov_len;
cpu_to_be16s(&code);
if (reason) {
buffer_append(&ioc->rawoutput, reason, strlen(reason));
iov[1].iov_base = (void *)reason;
iov[1].iov_len = strlen(reason);
size += iov[1].iov_len;
niov++;
}
iov.iov_base = ioc->rawoutput.buffer;
iov.iov_len = ioc->rawoutput.offset;
qio_channel_websock_encode(ioc, QIO_CHANNEL_WEBSOCK_OPCODE_CLOSE,
&iov, 1, iov.iov_len);
buffer_reset(&ioc->rawoutput);
iov, niov, size);
qio_channel_websock_write_wire(ioc, NULL);
qio_channel_shutdown(ioc->master, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
}
@ -893,7 +897,6 @@ static void qio_channel_websock_finalize(Object *obj)
buffer_free(&ioc->encinput);
buffer_free(&ioc->encoutput);
buffer_free(&ioc->rawinput);
buffer_free(&ioc->rawoutput);
object_unref(OBJECT(ioc->master));
if (ioc->io_tag) {
g_source_remove(ioc->io_tag);
@ -1103,8 +1106,8 @@ static ssize_t qio_channel_websock_writev(QIOChannel *ioc,
Error **errp)
{
QIOChannelWebsock *wioc = QIO_CHANNEL_WEBSOCK(ioc);
size_t i;
ssize_t done = 0;
ssize_t want = iov_size(iov, niov);
ssize_t avail;
ssize_t ret;
if (wioc->io_err) {
@ -1117,32 +1120,21 @@ static ssize_t qio_channel_websock_writev(QIOChannel *ioc,
return -1;
}
for (i = 0; i < niov; i++) {
size_t want = iov[i].iov_len;
if ((want + wioc->rawoutput.offset) > QIO_CHANNEL_WEBSOCK_MAX_BUFFER) {
want = (QIO_CHANNEL_WEBSOCK_MAX_BUFFER - wioc->rawoutput.offset);
}
if (want == 0) {
goto done;
}
buffer_reserve(&wioc->rawoutput, want);
buffer_append(&wioc->rawoutput, iov[i].iov_base, want);
done += want;
if (want < iov[i].iov_len) {
break;
}
avail = wioc->encoutput.offset >= QIO_CHANNEL_WEBSOCK_MAX_BUFFER ?
0 : (QIO_CHANNEL_WEBSOCK_MAX_BUFFER - wioc->encoutput.offset);
if (want > avail) {
want = avail;
}
done:
if (wioc->rawoutput.offset) {
struct iovec iov = { .iov_base = wioc->rawoutput.buffer,
.iov_len = wioc->rawoutput.offset };
if (want) {
qio_channel_websock_encode(wioc,
QIO_CHANNEL_WEBSOCK_OPCODE_BINARY_FRAME,
&iov, 1, iov.iov_len);
buffer_reset(&wioc->rawoutput);
iov, niov, want);
}
/* Even if want == 0, we'll try write_wire in case there's
* pending data we could usefully flush out
*/
ret = qio_channel_websock_write_wire(wioc, errp);
if (ret < 0 &&
ret != QIO_CHANNEL_ERR_BLOCK) {
@ -1152,11 +1144,11 @@ static ssize_t qio_channel_websock_writev(QIOChannel *ioc,
qio_channel_websock_set_watch(wioc);
if (done == 0) {
if (want == 0) {
return QIO_CHANNEL_ERR_BLOCK;
}
return done;
return want;
}
static int qio_channel_websock_set_blocking(QIOChannel *ioc,