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