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 "chardev/char-fe.h"
  17 #include "hw/s390x/3270-ccw.h"
  18
  19 /* Enough spaces for different window sizes. */
  20 #define INPUT_BUFFER_SIZE  1000
  21 /*
  22  * 1 for header, 1024*2 for datastream, 2 for tail
  23  * Reserve enough spaces for telnet IAC escape.
  24  */
  25 #define OUTPUT_BUFFER_SIZE 2051
  26
  27 typedef struct Terminal3270 {
  28     EmulatedCcw3270Device cdev;
  29     CharBackend chr;
  30     uint8_t inv[INPUT_BUFFER_SIZE];
  31     uint8_t outv[OUTPUT_BUFFER_SIZE];
  32     int in_len;
  33     int out_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 /*
  50  * Protocol handshake done,
  51  * signal guest by an unsolicited DE irq.
  52  */
  53 static void TN3270_handshake_done(Terminal3270 *t)
  54 {
  55     CcwDevice *ccw_dev = CCW_DEVICE(t);
  56     SubchDev *sch = ccw_dev->sch;
  57
  58     t->handshake_done = true;
  59     sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
  60     css_conditional_io_interrupt(sch);
  61 }
  62
  63 /*
  64  * Called when the interval is timeout to detect
  65  * if the client is still alive by Timing Mark.
  66  */
  67 static gboolean send_timing_mark_cb(gpointer opaque)
  68 {
  69     Terminal3270 *t = opaque;
  70     const uint8_t timing[] = {0xff, 0xfd, 0x06};
  71
  72     qemu_chr_fe_write_all(&t->chr, timing, sizeof(timing));
  73     return true;
  74 }
  75
  76 /*
  77  * Receive inbound data from socket.
  78  * For data given to guest, drop the data boundary IAC, IAC_EOR.
  79  * TODO:
  80  * Using "Reset" key on x3270 may result multiple commands in one packet.
  81  * This usually happens when the user meets a poor traffic of the network.
  82  * As of now, for such case, we simply terminate the connection,
  83  * and we should come back here later with a better solution.
  84  */
  85 static void terminal_read(void *opaque, const uint8_t *buf, int size)
  86 {
  87     Terminal3270 *t = opaque;
  88     CcwDevice *ccw_dev = CCW_DEVICE(t);
  89     SubchDev *sch = ccw_dev->sch;
  90     int end;
  91
  92     assert(size <= (INPUT_BUFFER_SIZE - t->in_len));
  93
  94     if (t->timer_tag) {
  95         g_source_remove(t->timer_tag);
  96         t->timer_tag = 0;
  97     }
  98     t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t);
  99
 100     memcpy(&t->inv[t->in_len], buf, size);
 101     t->in_len += size;
 102     if (t->in_len < 2) {
 103         return;
 104     }
 105
 106     if (!t->handshake_done) {
 107         /*
 108          * Receiving Terminal Type is the last step of handshake.
 109          * The data format: IAC SB Terminal-Type IS <terminal type> IAC SE
 110          * The code for Terminal-Type is 0x18, for IS is 0.
 111          * Simply check the data format and mark handshake_done.
 112          */
 113         if (t->in_len > 6 && t->inv[2] == 0x18 && t->inv[3] == 0x0 &&
 114             t->inv[t->in_len - 2] == IAC && t->inv[t->in_len - 1] == IAC_SE) {
 115             TN3270_handshake_done(t);
 116             t->in_len = 0;
 117         }
 118         return;
 119     }
 120
 121     for (end = 0; end < t->in_len - 1; end++) {
 122         if (t->inv[end] == IAC && t->inv[end + 1] == IAC_EOR) {
 123             break;
 124         }
 125     }
 126     if (end == t->in_len - 2) {
 127         /* Data is valid for consuming. */
 128         t->in_len -= 2;
 129         sch->curr_status.scsw.dstat = SCSW_DSTAT_ATTENTION;
 130         css_conditional_io_interrupt(sch);
 131     } else if (end < t->in_len - 2) {
 132         /* "Reset" key is used. */
 133         qemu_chr_fe_disconnect(&t->chr);
 134     } else {
 135         /* Gathering data. */
 136         return;
 137     }
 138 }
 139
 140 static void chr_event(void *opaque, int event)
 141 {
 142     Terminal3270 *t = opaque;
 143     CcwDevice *ccw_dev = CCW_DEVICE(t);
 144     SubchDev *sch = ccw_dev->sch;
 145
 146     /* Ensure the initial status correct, always reset them. */
 147     t->in_len = 0;
 148     t->out_len = 0;
 149     t->handshake_done = false;
 150     if (t->timer_tag) {
 151         g_source_remove(t->timer_tag);
 152         t->timer_tag = 0;
 153     }
 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
 235     assert(count <= (OUTPUT_BUFFER_SIZE - 3) / 2);
 236
 237     if (!t->handshake_done) {
 238         if (!(t->outv[0] == IAC && t->outv[1] != IAC)) {
 239             /*
 240              * Before having finished 3270 negotiation,
 241              * sending outbound data except protocol options is prohibited.
 242              */
 243             return 0;
 244         }
 245     }
 246     if (!qemu_chr_fe_backend_connected(&t->chr)) {
 247         /* We just say we consumed all data if there's no backend. */
 248         return count;
 249     }
 250     t->outv[0] = cmd;
 251     ccw_dstream_read_buf(get_cds(t), &t->outv[1], count);
 252     t->out_len = count + 1;
 253
 254     t->out_len = insert_IAC_escape_char(t->outv, t->out_len);
 255     t->outv[t->out_len++] = IAC;
 256     t->outv[t->out_len++] = IAC_EOR;
 257
 258     retval = qemu_chr_fe_write_all(&t->chr, t->outv, t->out_len);
 259     return (retval <= 0) ? 0 : (retval - 3);
 260 }
 261
 262 static Property terminal_properties[] = {
 263     DEFINE_PROP_CHR("chardev", Terminal3270, chr),
 264     DEFINE_PROP_END_OF_LIST(),
 265 };
 266
 267 static const VMStateDescription terminal3270_vmstate = {
 268     .name = TYPE_TERMINAL_3270,
 269     .unmigratable = 1,
 270 };
 271
 272 static void terminal_class_init(ObjectClass *klass, void *data)
 273 {
 274     DeviceClass *dc = DEVICE_CLASS(klass);
 275     EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
 276
 277     dc->props = terminal_properties;
 278     dc->vmsd = &terminal3270_vmstate;
 279     ck->init = terminal_init;
 280     ck->read_payload_3270 = read_payload_3270;
 281     ck->write_payload_3270 = write_payload_3270;
 282 }
 283
 284 static const TypeInfo ccw_terminal_info = {
 285     .name = TYPE_TERMINAL_3270,
 286     .parent = TYPE_EMULATED_CCW_3270,
 287     .instance_size = sizeof(Terminal3270),
 288     .class_init = terminal_class_init,
 289     .class_size = sizeof(EmulatedCcw3270Class),
 290 };
 291
 292 static void register_types(void)
 293 {
 294     type_register_static(&ccw_terminal_info);
 295 }
 296
 297 type_init(register_types)