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