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qemu/hw/char/terminal3270.c

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/*
* Terminal 3270 implementation
*
* Copyright 2017 IBM Corp.
*
* Authors: Yang Chen <bjcyang@linux.vnet.ibm.com>
* Jing Liu <liujbjl@linux.vnet.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or (at
* your option) any later version. See the COPYING file in the top-level
* directory.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/module.h"
#include "chardev/char-fe.h"
#include "hw/qdev-properties.h"
#include "hw/s390x/3270-ccw.h"
/* Enough spaces for different window sizes. */
#define INPUT_BUFFER_SIZE 1000
/*
* 1 for header, 1024*2 for datastream, 2 for tail
* Reserve enough spaces for telnet IAC escape.
*/
#define OUTPUT_BUFFER_SIZE 2051
typedef struct Terminal3270 {
EmulatedCcw3270Device cdev;
CharBackend chr;
uint8_t inv[INPUT_BUFFER_SIZE];
uint8_t outv[OUTPUT_BUFFER_SIZE];
int in_len;
bool handshake_done;
guint timer_tag;
} Terminal3270;
#define TYPE_TERMINAL_3270 "x-terminal3270"
#define TERMINAL_3270(obj) \
OBJECT_CHECK(Terminal3270, (obj), TYPE_TERMINAL_3270)
static int terminal_can_read(void *opaque)
{
Terminal3270 *t = opaque;
return INPUT_BUFFER_SIZE - t->in_len;
}
static void terminal_timer_cancel(Terminal3270 *t)
{
if (t->timer_tag) {
g_source_remove(t->timer_tag);
t->timer_tag = 0;
}
}
/*
* Protocol handshake done,
* signal guest by an unsolicited DE irq.
*/
static void TN3270_handshake_done(Terminal3270 *t)
{
CcwDevice *ccw_dev = CCW_DEVICE(t);
SubchDev *sch = ccw_dev->sch;
t->handshake_done = true;
sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
css_conditional_io_interrupt(sch);
}
/*
* Called when the interval is timeout to detect
* if the client is still alive by Timing Mark.
*/
static gboolean send_timing_mark_cb(gpointer opaque)
{
Terminal3270 *t = opaque;
const uint8_t timing[] = {0xff, 0xfd, 0x06};
qemu_chr_fe_write_all(&t->chr, timing, sizeof(timing));
return true;
}
/*
* Receive inbound data from socket.
* For data given to guest, drop the data boundary IAC, IAC_EOR.
* TODO:
* Using "Reset" key on x3270 may result multiple commands in one packet.
* This usually happens when the user meets a poor traffic of the network.
* As of now, for such case, we simply terminate the connection,
* and we should come back here later with a better solution.
*/
static void terminal_read(void *opaque, const uint8_t *buf, int size)
{
Terminal3270 *t = opaque;
CcwDevice *ccw_dev = CCW_DEVICE(t);
SubchDev *sch = ccw_dev->sch;
int end;
assert(size <= (INPUT_BUFFER_SIZE - t->in_len));
terminal_timer_cancel(t);
t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t);
memcpy(&t->inv[t->in_len], buf, size);
t->in_len += size;
if (t->in_len < 2) {
return;
}
if (!t->handshake_done) {
/*
* Receiving Terminal Type is the last step of handshake.
* The data format: IAC SB Terminal-Type IS <terminal type> IAC SE
* The code for Terminal-Type is 0x18, for IS is 0.
* Simply check the data format and mark handshake_done.
*/
if (t->in_len > 6 && t->inv[2] == 0x18 && t->inv[3] == 0x0 &&
t->inv[t->in_len - 2] == IAC && t->inv[t->in_len - 1] == IAC_SE) {
TN3270_handshake_done(t);
t->in_len = 0;
}
return;
}
for (end = 0; end < t->in_len - 1; end++) {
if (t->inv[end] == IAC && t->inv[end + 1] == IAC_EOR) {
break;
}
}
if (end == t->in_len - 2) {
/* Data is valid for consuming. */
t->in_len -= 2;
sch->curr_status.scsw.dstat = SCSW_DSTAT_ATTENTION;
css_conditional_io_interrupt(sch);
} else if (end < t->in_len - 2) {
/* "Reset" key is used. */
qemu_chr_fe_disconnect(&t->chr);
} else {
/* Gathering data. */
return;
}
}
static void chr_event(void *opaque, QEMUChrEvent event)
{
Terminal3270 *t = opaque;
CcwDevice *ccw_dev = CCW_DEVICE(t);
SubchDev *sch = ccw_dev->sch;
/* Ensure the initial status correct, always reset them. */
t->in_len = 0;
t->handshake_done = false;
terminal_timer_cancel(t);
switch (event) {
case CHR_EVENT_OPENED:
/*
* 3270 does handshake firstly by the negotiate options in
* char-socket.c. Once qemu receives the terminal-type of the
* client, mark handshake done and trigger everything rolling again.
*/
t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t);
break;
case CHR_EVENT_CLOSED:
sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
css_conditional_io_interrupt(sch);
break;
case CHR_EVENT_BREAK:
case CHR_EVENT_MUX_IN:
case CHR_EVENT_MUX_OUT:
/* Ignore */
break;
}
}
static void terminal_init(EmulatedCcw3270Device *dev, Error **errp)
{
Terminal3270 *t = TERMINAL_3270(dev);
static bool terminal_available;
if (terminal_available) {
error_setg(errp, "Multiple 3270 terminals are not supported.");
return;
}
terminal_available = true;
qemu_chr_fe_set_handlers(&t->chr, terminal_can_read,
terminal_read, chr_event, NULL, t, NULL, true);
}
static inline CcwDataStream *get_cds(Terminal3270 *t)
{
return &(CCW_DEVICE(&t->cdev)->sch->cds);
}
static int read_payload_3270(EmulatedCcw3270Device *dev)
{
Terminal3270 *t = TERMINAL_3270(dev);
int len;
len = MIN(ccw_dstream_avail(get_cds(t)), t->in_len);
ccw_dstream_write_buf(get_cds(t), t->inv, len);
t->in_len -= len;
return len;
}
/* TN3270 uses binary transmission, which needs escape IAC to IAC IAC */
static int insert_IAC_escape_char(uint8_t *outv, int out_len)
{
int IAC_num = 0, new_out_len, i, j;
for (i = 0; i < out_len; i++) {
if (outv[i] == IAC) {
IAC_num++;
}
}
if (IAC_num == 0) {
return out_len;
}
new_out_len = out_len + IAC_num;
for (i = out_len - 1, j = new_out_len - 1; j > i && i >= 0; i--, j--) {
outv[j] = outv[i];
if (outv[i] == IAC) {
outv[--j] = IAC;
}
}
return new_out_len;
}
/*
* Write 3270 outbound to socket.
* Return the count of 3270 data field if succeeded, zero if failed.
*/
static int write_payload_3270(EmulatedCcw3270Device *dev, uint8_t cmd)
{
Terminal3270 *t = TERMINAL_3270(dev);
int retval = 0;
int count = ccw_dstream_avail(get_cds(t));
int bound = (OUTPUT_BUFFER_SIZE - 3) / 2;
int len = MIN(count, bound);
int out_len = 0;
if (!t->handshake_done) {
if (!(t->outv[0] == IAC && t->outv[1] != IAC)) {
/*
* Before having finished 3270 negotiation,
* sending outbound data except protocol options is prohibited.
*/
return 0;
}
}
if (!qemu_chr_fe_backend_connected(&t->chr)) {
/* We just say we consumed all data if there's no backend. */
return count;
}
t->outv[out_len++] = cmd;
do {
ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
count = ccw_dstream_avail(get_cds(t));
out_len += len;
out_len = insert_IAC_escape_char(t->outv, out_len);
if (!count) {
t->outv[out_len++] = IAC;
t->outv[out_len++] = IAC_EOR;
}
retval = qemu_chr_fe_write_all(&t->chr, t->outv, out_len);
len = MIN(count, bound);
out_len = 0;
} while (len && retval >= 0);
return (retval <= 0) ? 0 : get_cds(t)->count;
}
static Property terminal_properties[] = {
DEFINE_PROP_CHR("chardev", Terminal3270, chr),
DEFINE_PROP_END_OF_LIST(),
};
static const VMStateDescription terminal3270_vmstate = {
.name = TYPE_TERMINAL_3270,
.unmigratable = 1,
};
static void terminal_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
device_class_set_props(dc, terminal_properties);
dc->vmsd = &terminal3270_vmstate;
ck->init = terminal_init;
ck->read_payload_3270 = read_payload_3270;
ck->write_payload_3270 = write_payload_3270;
}
static const TypeInfo ccw_terminal_info = {
.name = TYPE_TERMINAL_3270,
.parent = TYPE_EMULATED_CCW_3270,
.instance_size = sizeof(Terminal3270),
.class_init = terminal_class_init,
.class_size = sizeof(EmulatedCcw3270Class),
};
static void register_types(void)
{
type_register_static(&ccw_terminal_info);
}
type_init(register_types)
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