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