hw/char/terminal3270.c - third_party/qemu - Git at Google

 /*
  * 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/qdev-properties-system.h"
 #include "hw/s390x/3270-ccw.h"
 #include "qom/object.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

 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;
 };
 typedef struct Terminal3270 Terminal3270;

 #define TYPE_TERMINAL_3270 "x-terminal3270"
 DECLARE_INSTANCE_CHECKER(Terminal3270, TERMINAL_3270,
                          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;
     int ret;

     len = MIN(ccw_dstream_avail(get_cds(t)), t->in_len);
     ret = ccw_dstream_write_buf(get_cds(t), t->inv, len);
     if (ret < 0) {
         return ret;
     }
     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 {
         retval = ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
         if (retval < 0) {
             return retval;
         }
         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)
	/*
	* 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/qdev-properties-system.h"
	#include "hw/s390x/3270-ccw.h"
	#include "qom/object.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

	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;
	};
	typedef struct Terminal3270 Terminal3270;

	#define TYPE_TERMINAL_3270 "x-terminal3270"
	DECLARE_INSTANCE_CHECKER(Terminal3270, TERMINAL_3270,
	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;
	int ret;

	len = MIN(ccw_dstream_avail(get_cds(t)), t->in_len);
	ret = ccw_dstream_write_buf(get_cds(t), t->inv, len);
	if (ret < 0) {
	return ret;
	}
	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 {
	retval = ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
	if (retval < 0) {
	return retval;
	}
	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)