a2458b6f69
GNUTLS takes a paranoid approach when seeing 0 bytes returned by the underlying OS read() function. It will consider this an error and return GNUTLS_E_PREMATURE_TERMINATION instead of propagating the 0 return value. It expects apps to arrange for clean termination at the protocol level and not rely on seeing EOF from a read call to detect shutdown. This is to harden apps against a malicious 3rd party causing termination of the sockets layer. This is unhelpful for the QEMU NBD code which does have a clean protocol level shutdown, but still relies on seeing 0 from the I/O channel read in the coroutine handling incoming replies. The upshot is that when using a plain NBD connection shutdown is silent, but when using TLS, the client spams the console with Cannot read from TLS channel: Broken pipe The NBD connection has, however, called qio_channel_shutdown() at this point to indicate that it is done with I/O. This gives the opportunity to optimize the code such that when the channel has been shutdown in the read direction, the error code GNUTLS_E_PREMATURE_TERMINATION gets turned into a '0' return instead of an error. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20181119134228.11031-1-berrange@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com>
432 lines
12 KiB
C
432 lines
12 KiB
C
/*
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* QEMU I/O channels TLS driver
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*
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* Copyright (c) 2015 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "io/channel-tls.h"
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#include "trace.h"
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static ssize_t qio_channel_tls_write_handler(const char *buf,
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size_t len,
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void *opaque)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(opaque);
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ssize_t ret;
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ret = qio_channel_write(tioc->master, buf, len, NULL);
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if (ret == QIO_CHANNEL_ERR_BLOCK) {
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errno = EAGAIN;
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return -1;
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} else if (ret < 0) {
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errno = EIO;
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return -1;
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}
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return ret;
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}
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static ssize_t qio_channel_tls_read_handler(char *buf,
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size_t len,
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void *opaque)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(opaque);
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ssize_t ret;
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ret = qio_channel_read(tioc->master, buf, len, NULL);
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if (ret == QIO_CHANNEL_ERR_BLOCK) {
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errno = EAGAIN;
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return -1;
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} else if (ret < 0) {
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errno = EIO;
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return -1;
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}
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return ret;
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}
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QIOChannelTLS *
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qio_channel_tls_new_server(QIOChannel *master,
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QCryptoTLSCreds *creds,
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const char *aclname,
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Error **errp)
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{
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QIOChannelTLS *ioc;
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ioc = QIO_CHANNEL_TLS(object_new(TYPE_QIO_CHANNEL_TLS));
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ioc->master = master;
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object_ref(OBJECT(master));
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ioc->session = qcrypto_tls_session_new(
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creds,
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NULL,
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aclname,
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QCRYPTO_TLS_CREDS_ENDPOINT_SERVER,
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errp);
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if (!ioc->session) {
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goto error;
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}
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qcrypto_tls_session_set_callbacks(
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ioc->session,
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qio_channel_tls_write_handler,
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qio_channel_tls_read_handler,
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ioc);
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trace_qio_channel_tls_new_server(ioc, master, creds, aclname);
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return ioc;
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error:
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object_unref(OBJECT(ioc));
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return NULL;
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}
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QIOChannelTLS *
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qio_channel_tls_new_client(QIOChannel *master,
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QCryptoTLSCreds *creds,
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const char *hostname,
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Error **errp)
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{
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QIOChannelTLS *tioc;
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QIOChannel *ioc;
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tioc = QIO_CHANNEL_TLS(object_new(TYPE_QIO_CHANNEL_TLS));
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ioc = QIO_CHANNEL(tioc);
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tioc->master = master;
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if (qio_channel_has_feature(master, QIO_CHANNEL_FEATURE_SHUTDOWN)) {
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qio_channel_set_feature(ioc, QIO_CHANNEL_FEATURE_SHUTDOWN);
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}
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object_ref(OBJECT(master));
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tioc->session = qcrypto_tls_session_new(
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creds,
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hostname,
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NULL,
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QCRYPTO_TLS_CREDS_ENDPOINT_CLIENT,
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errp);
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if (!tioc->session) {
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goto error;
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}
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qcrypto_tls_session_set_callbacks(
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tioc->session,
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qio_channel_tls_write_handler,
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qio_channel_tls_read_handler,
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tioc);
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trace_qio_channel_tls_new_client(tioc, master, creds, hostname);
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return tioc;
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error:
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object_unref(OBJECT(tioc));
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return NULL;
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}
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struct QIOChannelTLSData {
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QIOTask *task;
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GMainContext *context;
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};
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typedef struct QIOChannelTLSData QIOChannelTLSData;
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static gboolean qio_channel_tls_handshake_io(QIOChannel *ioc,
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GIOCondition condition,
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gpointer user_data);
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static void qio_channel_tls_handshake_task(QIOChannelTLS *ioc,
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QIOTask *task,
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GMainContext *context)
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{
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Error *err = NULL;
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QCryptoTLSSessionHandshakeStatus status;
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if (qcrypto_tls_session_handshake(ioc->session, &err) < 0) {
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trace_qio_channel_tls_handshake_fail(ioc);
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qio_task_set_error(task, err);
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qio_task_complete(task);
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return;
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}
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status = qcrypto_tls_session_get_handshake_status(ioc->session);
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if (status == QCRYPTO_TLS_HANDSHAKE_COMPLETE) {
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trace_qio_channel_tls_handshake_complete(ioc);
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if (qcrypto_tls_session_check_credentials(ioc->session,
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&err) < 0) {
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trace_qio_channel_tls_credentials_deny(ioc);
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qio_task_set_error(task, err);
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} else {
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trace_qio_channel_tls_credentials_allow(ioc);
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}
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qio_task_complete(task);
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} else {
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GIOCondition condition;
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QIOChannelTLSData *data = g_new0(typeof(*data), 1);
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data->task = task;
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data->context = context;
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if (context) {
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g_main_context_ref(context);
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}
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if (status == QCRYPTO_TLS_HANDSHAKE_SENDING) {
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condition = G_IO_OUT;
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} else {
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condition = G_IO_IN;
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}
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trace_qio_channel_tls_handshake_pending(ioc, status);
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qio_channel_add_watch_full(ioc->master,
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condition,
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qio_channel_tls_handshake_io,
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data,
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NULL,
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context);
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}
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}
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static gboolean qio_channel_tls_handshake_io(QIOChannel *ioc,
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GIOCondition condition,
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gpointer user_data)
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{
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QIOChannelTLSData *data = user_data;
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QIOTask *task = data->task;
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GMainContext *context = data->context;
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(
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qio_task_get_source(task));
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g_free(data);
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qio_channel_tls_handshake_task(tioc, task, context);
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if (context) {
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g_main_context_unref(context);
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}
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return FALSE;
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}
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void qio_channel_tls_handshake(QIOChannelTLS *ioc,
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QIOTaskFunc func,
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gpointer opaque,
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GDestroyNotify destroy,
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GMainContext *context)
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{
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QIOTask *task;
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task = qio_task_new(OBJECT(ioc),
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func, opaque, destroy);
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trace_qio_channel_tls_handshake_start(ioc);
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qio_channel_tls_handshake_task(ioc, task, context);
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}
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static void qio_channel_tls_init(Object *obj G_GNUC_UNUSED)
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{
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}
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static void qio_channel_tls_finalize(Object *obj)
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{
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QIOChannelTLS *ioc = QIO_CHANNEL_TLS(obj);
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object_unref(OBJECT(ioc->master));
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qcrypto_tls_session_free(ioc->session);
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}
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static ssize_t qio_channel_tls_readv(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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int **fds,
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size_t *nfds,
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Error **errp)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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size_t i;
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ssize_t got = 0;
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for (i = 0 ; i < niov ; i++) {
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ssize_t ret = qcrypto_tls_session_read(tioc->session,
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iov[i].iov_base,
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iov[i].iov_len);
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if (ret < 0) {
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if (errno == EAGAIN) {
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if (got) {
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return got;
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} else {
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return QIO_CHANNEL_ERR_BLOCK;
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}
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} else if (errno == ECONNABORTED &&
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(tioc->shutdown & QIO_CHANNEL_SHUTDOWN_READ)) {
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return 0;
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}
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error_setg_errno(errp, errno,
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"Cannot read from TLS channel");
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return -1;
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}
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got += ret;
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if (ret < iov[i].iov_len) {
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break;
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}
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}
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return got;
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}
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static ssize_t qio_channel_tls_writev(QIOChannel *ioc,
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const struct iovec *iov,
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size_t niov,
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int *fds,
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size_t nfds,
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Error **errp)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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size_t i;
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ssize_t done = 0;
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for (i = 0 ; i < niov ; i++) {
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ssize_t ret = qcrypto_tls_session_write(tioc->session,
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iov[i].iov_base,
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iov[i].iov_len);
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if (ret <= 0) {
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if (errno == EAGAIN) {
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if (done) {
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return done;
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} else {
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return QIO_CHANNEL_ERR_BLOCK;
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}
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}
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error_setg_errno(errp, errno,
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"Cannot write to TLS channel");
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return -1;
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}
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done += ret;
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if (ret < iov[i].iov_len) {
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break;
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}
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}
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return done;
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}
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static int qio_channel_tls_set_blocking(QIOChannel *ioc,
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bool enabled,
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Error **errp)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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return qio_channel_set_blocking(tioc->master, enabled, errp);
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}
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static void qio_channel_tls_set_delay(QIOChannel *ioc,
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bool enabled)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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qio_channel_set_delay(tioc->master, enabled);
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}
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static void qio_channel_tls_set_cork(QIOChannel *ioc,
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bool enabled)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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qio_channel_set_cork(tioc->master, enabled);
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}
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static int qio_channel_tls_shutdown(QIOChannel *ioc,
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QIOChannelShutdown how,
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Error **errp)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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tioc->shutdown |= how;
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return qio_channel_shutdown(tioc->master, how, errp);
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}
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static int qio_channel_tls_close(QIOChannel *ioc,
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Error **errp)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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return qio_channel_close(tioc->master, errp);
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}
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static void qio_channel_tls_set_aio_fd_handler(QIOChannel *ioc,
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AioContext *ctx,
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IOHandler *io_read,
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IOHandler *io_write,
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void *opaque)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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qio_channel_set_aio_fd_handler(tioc->master, ctx, io_read, io_write, opaque);
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}
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static GSource *qio_channel_tls_create_watch(QIOChannel *ioc,
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GIOCondition condition)
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{
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QIOChannelTLS *tioc = QIO_CHANNEL_TLS(ioc);
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return qio_channel_create_watch(tioc->master, condition);
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}
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QCryptoTLSSession *
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qio_channel_tls_get_session(QIOChannelTLS *ioc)
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{
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return ioc->session;
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}
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static void qio_channel_tls_class_init(ObjectClass *klass,
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void *class_data G_GNUC_UNUSED)
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{
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QIOChannelClass *ioc_klass = QIO_CHANNEL_CLASS(klass);
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ioc_klass->io_writev = qio_channel_tls_writev;
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ioc_klass->io_readv = qio_channel_tls_readv;
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ioc_klass->io_set_blocking = qio_channel_tls_set_blocking;
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ioc_klass->io_set_delay = qio_channel_tls_set_delay;
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ioc_klass->io_set_cork = qio_channel_tls_set_cork;
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ioc_klass->io_close = qio_channel_tls_close;
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ioc_klass->io_shutdown = qio_channel_tls_shutdown;
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ioc_klass->io_create_watch = qio_channel_tls_create_watch;
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ioc_klass->io_set_aio_fd_handler = qio_channel_tls_set_aio_fd_handler;
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}
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static const TypeInfo qio_channel_tls_info = {
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.parent = TYPE_QIO_CHANNEL,
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.name = TYPE_QIO_CHANNEL_TLS,
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.instance_size = sizeof(QIOChannelTLS),
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.instance_init = qio_channel_tls_init,
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.instance_finalize = qio_channel_tls_finalize,
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.class_init = qio_channel_tls_class_init,
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};
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static void qio_channel_tls_register_types(void)
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{
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type_register_static(&qio_channel_tls_info);
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}
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type_init(qio_channel_tls_register_types);
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