hw/char/terminal3270.c

   1 /*
   2  * Terminal 3270 implementation
   3  *
   4  * Copyright 2017 IBM Corp.
   5  *
   6  * Authors: Yang Chen <bjcyang@linux.vnet.ibm.com>
   7  *          Jing Liu <liujbjl@linux.vnet.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or (at
  10  * your option) any later version. See the COPYING file in the top-level
  11  * directory.
  12  */
  13
  14 #include "qemu/osdep.h"
  15 #include "qapi/error.h"
  16 #include "qemu/module.h"
  17 #include "chardev/char-fe.h"
  18 #include "hw/qdev-properties.h"
  19 #include "hw/qdev-properties-system.h"
  20 #include "hw/s390x/3270-ccw.h"
  21 #include "qom/object.h"
  22
  23 /* Enough spaces for different window sizes. */
  24 #define INPUT_BUFFER_SIZE  1000
  25 /*
  26  * 1 for header, 1024*2 for datastream, 2 for tail
  27  * Reserve enough spaces for telnet IAC escape.
  28  */
  29 #define OUTPUT_BUFFER_SIZE 2051
  30
  31 struct Terminal3270 {
  32     EmulatedCcw3270Device cdev;
  33     CharBackend chr;
  34     uint8_t inv[INPUT_BUFFER_SIZE];
  35     uint8_t outv[OUTPUT_BUFFER_SIZE];
  36     int in_len;
  37     bool handshake_done;
  38     guint timer_tag;
  39 };
  40 typedef struct Terminal3270 Terminal3270;
  41
  42 #define TYPE_TERMINAL_3270 "x-terminal3270"
  43 DECLARE_INSTANCE_CHECKER(Terminal3270, TERMINAL_3270,
  44                          TYPE_TERMINAL_3270)
  45
  46 static int terminal_can_read(void *opaque)
  47 {
  48     Terminal3270 *t = opaque;
  49
  50     return INPUT_BUFFER_SIZE - t->in_len;
  51 }
  52
  53 static void terminal_timer_cancel(Terminal3270 *t)
  54 {
  55     if (t->timer_tag) {
  56         g_source_remove(t->timer_tag);
  57         t->timer_tag = 0;
  58     }
  59 }
  60
  61 /*
  62  * Protocol handshake done,
  63  * signal guest by an unsolicited DE irq.
  64  */
  65 static void TN3270_handshake_done(Terminal3270 *t)
  66 {
  67     CcwDevice *ccw_dev = CCW_DEVICE(t);
  68     SubchDev *sch = ccw_dev->sch;
  69
  70     t->handshake_done = true;
  71     sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
  72     css_conditional_io_interrupt(sch);
  73 }
  74
  75 /*
  76  * Called when the interval is timeout to detect
  77  * if the client is still alive by Timing Mark.
  78  */
  79 static gboolean send_timing_mark_cb(gpointer opaque)
  80 {
  81     Terminal3270 *t = opaque;
  82     const uint8_t timing[] = {0xff, 0xfd, 0x06};
  83
  84     qemu_chr_fe_write_all(&t->chr, timing, sizeof(timing));
  85     return true;
  86 }
  87
  88 /*
  89  * Receive inbound data from socket.
  90  * For data given to guest, drop the data boundary IAC, IAC_EOR.
  91  * TODO:
  92  * Using "Reset" key on x3270 may result multiple commands in one packet.
  93  * This usually happens when the user meets a poor traffic of the network.
  94  * As of now, for such case, we simply terminate the connection,
  95  * and we should come back here later with a better solution.
  96  */
  97 static void terminal_read(void *opaque, const uint8_t *buf, int size)
  98 {
  99     Terminal3270 *t = opaque;
 100     CcwDevice *ccw_dev = CCW_DEVICE(t);
 101     SubchDev *sch = ccw_dev->sch;
 102     int end;
 103
 104     assert(size <= (INPUT_BUFFER_SIZE - t->in_len));
 105
 106     terminal_timer_cancel(t);
 107     t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t);
 108     memcpy(&t->inv[t->in_len], buf, size);
 109     t->in_len += size;
 110     if (t->in_len < 2) {
 111         return;
 112     }
 113
 114     if (!t->handshake_done) {
 115         /*
 116          * Receiving Terminal Type is the last step of handshake.
 117          * The data format: IAC SB Terminal-Type IS <terminal type> IAC SE
 118          * The code for Terminal-Type is 0x18, for IS is 0.
 119          * Simply check the data format and mark handshake_done.
 120          */
 121         if (t->in_len > 6 && t->inv[2] == 0x18 && t->inv[3] == 0x0 &&
 122             t->inv[t->in_len - 2] == IAC && t->inv[t->in_len - 1] == IAC_SE) {
 123             TN3270_handshake_done(t);
 124             t->in_len = 0;
 125         }
 126         return;
 127     }
 128
 129     for (end = 0; end < t->in_len - 1; end++) {
 130         if (t->inv[end] == IAC && t->inv[end + 1] == IAC_EOR) {
 131             break;
 132         }
 133     }
 134     if (end == t->in_len - 2) {
 135         /* Data is valid for consuming. */
 136         t->in_len -= 2;
 137         sch->curr_status.scsw.dstat = SCSW_DSTAT_ATTENTION;
 138         css_conditional_io_interrupt(sch);
 139     } else if (end < t->in_len - 2) {
 140         /* "Reset" key is used. */
 141         qemu_chr_fe_disconnect(&t->chr);
 142     } else {
 143         /* Gathering data. */
 144         return;
 145     }
 146 }
 147
 148 static void chr_event(void *opaque, QEMUChrEvent event)
 149 {
 150     Terminal3270 *t = opaque;
 151     CcwDevice *ccw_dev = CCW_DEVICE(t);
 152     SubchDev *sch = ccw_dev->sch;
 153
 154     /* Ensure the initial status correct, always reset them. */
 155     t->in_len = 0;
 156     t->handshake_done = false;
 157     terminal_timer_cancel(t);
 158
 159     switch (event) {
 160     case CHR_EVENT_OPENED:
 161         /*
 162          * 3270 does handshake firstly by the negotiate options in
 163          * char-socket.c. Once qemu receives the terminal-type of the
 164          * client, mark handshake done and trigger everything rolling again.
 165          */
 166         t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t);
 167         break;
 168     case CHR_EVENT_CLOSED:
 169         sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
 170         css_conditional_io_interrupt(sch);
 171         break;
 172     case CHR_EVENT_BREAK:
 173     case CHR_EVENT_MUX_IN:
 174     case CHR_EVENT_MUX_OUT:
 175         /* Ignore */
 176         break;
 177     }
 178 }
 179
 180 static void terminal_init(EmulatedCcw3270Device *dev, Error **errp)
 181 {
 182     Terminal3270 *t = TERMINAL_3270(dev);
 183     static bool terminal_available;
 184
 185     if (terminal_available) {
 186         error_setg(errp, "Multiple 3270 terminals are not supported.");
 187         return;
 188     }
 189     terminal_available = true;
 190     qemu_chr_fe_set_handlers(&t->chr, terminal_can_read,
 191                              terminal_read, chr_event, NULL, t, NULL, true);
 192 }
 193
 194 static inline CcwDataStream *get_cds(Terminal3270 *t)
 195 {
 196     return &(CCW_DEVICE(&t->cdev)->sch->cds);
 197 }
 198
 199 static int read_payload_3270(EmulatedCcw3270Device *dev)
 200 {
 201     Terminal3270 *t = TERMINAL_3270(dev);
 202     int len;
 203
 204     len = MIN(ccw_dstream_avail(get_cds(t)), t->in_len);
 205     ccw_dstream_write_buf(get_cds(t), t->inv, len);
 206     t->in_len -= len;
 207
 208     return len;
 209 }
 210
 211 /* TN3270 uses binary transmission, which needs escape IAC to IAC IAC */
 212 static int insert_IAC_escape_char(uint8_t *outv, int out_len)
 213 {
 214     int IAC_num = 0, new_out_len, i, j;
 215
 216     for (i = 0; i < out_len; i++) {
 217         if (outv[i] == IAC) {
 218             IAC_num++;
 219         }
 220     }
 221     if (IAC_num == 0) {
 222         return out_len;
 223     }
 224     new_out_len = out_len + IAC_num;
 225     for (i = out_len - 1, j = new_out_len - 1; j > i && i >= 0; i--, j--) {
 226         outv[j] = outv[i];
 227         if (outv[i] == IAC) {
 228             outv[--j] = IAC;
 229         }
 230     }
 231     return new_out_len;
 232 }
 233
 234 /*
 235  * Write 3270 outbound to socket.
 236  * Return the count of 3270 data field if succeeded, zero if failed.
 237  */
 238 static int write_payload_3270(EmulatedCcw3270Device *dev, uint8_t cmd)
 239 {
 240     Terminal3270 *t = TERMINAL_3270(dev);
 241     int retval = 0;
 242     int count = ccw_dstream_avail(get_cds(t));
 243     int bound = (OUTPUT_BUFFER_SIZE - 3) / 2;
 244     int len = MIN(count, bound);
 245     int out_len = 0;
 246
 247     if (!t->handshake_done) {
 248         if (!(t->outv[0] == IAC && t->outv[1] != IAC)) {
 249             /*
 250              * Before having finished 3270 negotiation,
 251              * sending outbound data except protocol options is prohibited.
 252              */
 253             return 0;
 254         }
 255     }
 256     if (!qemu_chr_fe_backend_connected(&t->chr)) {
 257         /* We just say we consumed all data if there's no backend. */
 258         return count;
 259     }
 260
 261     t->outv[out_len++] = cmd;
 262     do {
 263         ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
 264         count = ccw_dstream_avail(get_cds(t));
 265         out_len += len;
 266
 267         out_len = insert_IAC_escape_char(t->outv, out_len);
 268         if (!count) {
 269             t->outv[out_len++] = IAC;
 270             t->outv[out_len++] = IAC_EOR;
 271         }
 272         retval = qemu_chr_fe_write_all(&t->chr, t->outv, out_len);
 273         len = MIN(count, bound);
 274         out_len = 0;
 275     } while (len && retval >= 0);
 276     return (retval <= 0) ? 0 : get_cds(t)->count;
 277 }
 278
 279 static Property terminal_properties[] = {
 280     DEFINE_PROP_CHR("chardev", Terminal3270, chr),
 281     DEFINE_PROP_END_OF_LIST(),
 282 };
 283
 284 static const VMStateDescription terminal3270_vmstate = {
 285     .name = TYPE_TERMINAL_3270,
 286     .unmigratable = 1,
 287 };
 288
 289 static void terminal_class_init(ObjectClass *klass, void *data)
 290 {
 291     DeviceClass *dc = DEVICE_CLASS(klass);
 292     EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
 293
 294     device_class_set_props(dc, terminal_properties);
 295     dc->vmsd = &terminal3270_vmstate;
 296     ck->init = terminal_init;
 297     ck->read_payload_3270 = read_payload_3270;
 298     ck->write_payload_3270 = write_payload_3270;
 299 }
 300
 301 static const TypeInfo ccw_terminal_info = {
 302     .name = TYPE_TERMINAL_3270,
 303     .parent = TYPE_EMULATED_CCW_3270,
 304     .instance_size = sizeof(Terminal3270),
 305     .class_init = terminal_class_init,
 306     .class_size = sizeof(EmulatedCcw3270Class),
 307 };
 308
 309 static void register_types(void)
 310 {
 311     type_register_static(&ccw_terminal_info);
 312 }
 313
 314 type_init(register_types)