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authorDaniel P. Berrange <berrange@redhat.com>2017-10-09 16:54:07 +0100
committerDaniel P. Berrange <berrange@redhat.com>2017-10-16 16:57:08 +0100
commit8dfd5f96515ca20c4eb109cb0ee28e2bb32fc505 (patch)
treeefe8a11fd65642f3a7c3c22ad53609827eb797f8 /io/channel-websock.c
parentfb74e5903914b9ec8c80b6f7a35da000f9f92ae7 (diff)
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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>
Diffstat (limited to 'io/channel-websock.c')
-rw-r--r--io/channel-websock.c64
1 files changed, 28 insertions, 36 deletions
diff --git a/io/channel-websock.c b/io/channel-websock.c
index 93c06f5..e82b1be 100644
--- a/io/channel-websock.c
+++ b/io/channel-websock.c
@@ -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,