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     bool handshake_done;
  34     guint timer_tag;
  35 } Terminal3270;
  36
  37 #define TYPE_TERMINAL_3270 "x-terminal3270"
  38 #define TERMINAL_3270(obj) \
  39         OBJECT_CHECK(Terminal3270, (obj), TYPE_TERMINAL_3270)
  40
  41 static int terminal_can_read(void *opaque)
  42 {
  43     Terminal3270 *t = opaque;
  44
  45     return INPUT_BUFFER_SIZE - t->in_len;
  46 }
  47
  48 static void terminal_timer_cancel(Terminal3270 *t)
  49 {
  50     if (t->timer_tag) {
  51         g_source_remove(t->timer_tag);
  52         t->timer_tag = 0;
  53     }
  54 }
  55
  56 /*
  57  * Protocol handshake done,
  58  * signal guest by an unsolicited DE irq.
  59  */
  60 static void TN3270_handshake_done(Terminal3270 *t)
  61 {
  62     CcwDevice *ccw_dev = CCW_DEVICE(t);
  63     SubchDev *sch = ccw_dev->sch;
  64
  65     t->handshake_done = true;
  66     sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
  67     css_conditional_io_interrupt(sch);
  68 }
  69
  70 /*
  71  * Called when the interval is timeout to detect
  72  * if the client is still alive by Timing Mark.
  73  */
  74 static gboolean send_timing_mark_cb(gpointer opaque)
  75 {
  76     Terminal3270 *t = opaque;
  77     const uint8_t timing[] = {0xff, 0xfd, 0x06};
  78
  79     qemu_chr_fe_write_all(&t->chr, timing, sizeof(timing));
  80     return true;
  81 }
  82
  83 /*
  84  * Receive inbound data from socket.
  85  * For data given to guest, drop the data boundary IAC, IAC_EOR.
  86  * TODO:
  87  * Using "Reset" key on x3270 may result multiple commands in one packet.
  88  * This usually happens when the user meets a poor traffic of the network.
  89  * As of now, for such case, we simply terminate the connection,
  90  * and we should come back here later with a better solution.
  91  */
  92 static void terminal_read(void *opaque, const uint8_t *buf, int size)
  93 {
  94     Terminal3270 *t = opaque;
  95     CcwDevice *ccw_dev = CCW_DEVICE(t);
  96     SubchDev *sch = ccw_dev->sch;
  97     int end;
  98
  99     assert(size <= (INPUT_BUFFER_SIZE - t->in_len));
 100
 101     terminal_timer_cancel(t);
 102     t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t);
 103     memcpy(&t->inv[t->in_len], buf, size);
 104     t->in_len += size;
 105     if (t->in_len < 2) {
 106         return;
 107     }
 108
 109     if (!t->handshake_done) {
 110         /*
 111          * Receiving Terminal Type is the last step of handshake.
 112          * The data format: IAC SB Terminal-Type IS <terminal type> IAC SE
 113          * The code for Terminal-Type is 0x18, for IS is 0.
 114          * Simply check the data format and mark handshake_done.
 115          */
 116         if (t->in_len > 6 && t->inv[2] == 0x18 && t->inv[3] == 0x0 &&
 117             t->inv[t->in_len - 2] == IAC && t->inv[t->in_len - 1] == IAC_SE) {
 118             TN3270_handshake_done(t);
 119             t->in_len = 0;
 120         }
 121         return;
 122     }
 123
 124     for (end = 0; end < t->in_len - 1; end++) {
 125         if (t->inv[end] == IAC && t->inv[end + 1] == IAC_EOR) {
 126             break;
 127         }
 128     }
 129     if (end == t->in_len - 2) {
 130         /* Data is valid for consuming. */
 131         t->in_len -= 2;
 132         sch->curr_status.scsw.dstat = SCSW_DSTAT_ATTENTION;
 133         css_conditional_io_interrupt(sch);
 134     } else if (end < t->in_len - 2) {
 135         /* "Reset" key is used. */
 136         qemu_chr_fe_disconnect(&t->chr);
 137     } else {
 138         /* Gathering data. */
 139         return;
 140     }
 141 }
 142
 143 static void chr_event(void *opaque, int event)
 144 {
 145     Terminal3270 *t = opaque;
 146     CcwDevice *ccw_dev = CCW_DEVICE(t);
 147     SubchDev *sch = ccw_dev->sch;
 148
 149     /* Ensure the initial status correct, always reset them. */
 150     t->in_len = 0;
 151     t->handshake_done = false;
 152     terminal_timer_cancel(t);
 153
 154     switch (event) {
 155     case CHR_EVENT_OPENED:
 156         /*
 157          * 3270 does handshake firstly by the negotiate options in
 158          * char-socket.c. Once qemu receives the terminal-type of the
 159          * client, mark handshake done and trigger everything rolling again.
 160          */
 161         t->timer_tag = g_timeout_add_seconds(600, send_timing_mark_cb, t);
 162         break;
 163     case CHR_EVENT_CLOSED:
 164         sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
 165         css_conditional_io_interrupt(sch);
 166         break;
 167     }
 168 }
 169
 170 static void terminal_init(EmulatedCcw3270Device *dev, Error **errp)
 171 {
 172     Terminal3270 *t = TERMINAL_3270(dev);
 173     static bool terminal_available;
 174
 175     if (terminal_available) {
 176         error_setg(errp, "Multiple 3270 terminals are not supported.");
 177         return;
 178     }
 179     terminal_available = true;
 180     qemu_chr_fe_set_handlers(&t->chr, terminal_can_read,
 181                              terminal_read, chr_event, NULL, t, NULL, true);
 182 }
 183
 184 static inline CcwDataStream *get_cds(Terminal3270 *t)
 185 {
 186     return &(CCW_DEVICE(&t->cdev)->sch->cds);
 187 }
 188
 189 static int read_payload_3270(EmulatedCcw3270Device *dev)
 190 {
 191     Terminal3270 *t = TERMINAL_3270(dev);
 192     int len;
 193
 194     len = MIN(ccw_dstream_avail(get_cds(t)), t->in_len);
 195     ccw_dstream_write_buf(get_cds(t), t->inv, len);
 196     t->in_len -= len;
 197
 198     return len;
 199 }
 200
 201 /* TN3270 uses binary transmission, which needs escape IAC to IAC IAC */
 202 static int insert_IAC_escape_char(uint8_t *outv, int out_len)
 203 {
 204     int IAC_num = 0, new_out_len, i, j;
 205
 206     for (i = 0; i < out_len; i++) {
 207         if (outv[i] == IAC) {
 208             IAC_num++;
 209         }
 210     }
 211     if (IAC_num == 0) {
 212         return out_len;
 213     }
 214     new_out_len = out_len + IAC_num;
 215     for (i = out_len - 1, j = new_out_len - 1; j > i && i >= 0; i--, j--) {
 216         outv[j] = outv[i];
 217         if (outv[i] == IAC) {
 218             outv[--j] = IAC;
 219         }
 220     }
 221     return new_out_len;
 222 }
 223
 224 /*
 225  * Write 3270 outbound to socket.
 226  * Return the count of 3270 data field if succeeded, zero if failed.
 227  */
 228 static int write_payload_3270(EmulatedCcw3270Device *dev, uint8_t cmd)
 229 {
 230     Terminal3270 *t = TERMINAL_3270(dev);
 231     int retval = 0;
 232     int count = ccw_dstream_avail(get_cds(t));
 233     int bound = (OUTPUT_BUFFER_SIZE - 3) / 2;
 234     int len = MIN(count, bound);
 235     int out_len = 0;
 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
 251     t->outv[out_len++] = cmd;
 252     do {
 253         ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
 254         count = ccw_dstream_avail(get_cds(t));
 255         out_len += len;
 256
 257         out_len = insert_IAC_escape_char(t->outv, out_len);
 258         if (!count) {
 259             t->outv[out_len++] = IAC;
 260             t->outv[out_len++] = IAC_EOR;
 261         }
 262         retval = qemu_chr_fe_write_all(&t->chr, t->outv, out_len);
 263         len = MIN(count, bound);
 264         out_len = 0;
 265     } while (len && retval >= 0);
 266     return (retval <= 0) ? 0 : get_cds(t)->count;
 267 }
 268
 269 static Property terminal_properties[] = {
 270     DEFINE_PROP_CHR("chardev", Terminal3270, chr),
 271     DEFINE_PROP_END_OF_LIST(),
 272 };
 273
 274 static const VMStateDescription terminal3270_vmstate = {
 275     .name = TYPE_TERMINAL_3270,
 276     .unmigratable = 1,
 277 };
 278
 279 static void terminal_class_init(ObjectClass *klass, void *data)
 280 {
 281     DeviceClass *dc = DEVICE_CLASS(klass);
 282     EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
 283
 284     dc->props = terminal_properties;
 285     dc->vmsd = &terminal3270_vmstate;
 286     ck->init = terminal_init;
 287     ck->read_payload_3270 = read_payload_3270;
 288     ck->write_payload_3270 = write_payload_3270;
 289 }
 290
 291 static const TypeInfo ccw_terminal_info = {
 292     .name = TYPE_TERMINAL_3270,
 293     .parent = TYPE_EMULATED_CCW_3270,
 294     .instance_size = sizeof(Terminal3270),
 295     .class_init = terminal_class_init,
 296     .class_size = sizeof(EmulatedCcw3270Class),
 297 };
 298
 299 static void register_types(void)
 300 {
 301     type_register_static(&ccw_terminal_info);
 302 }
 303
 304 type_init(register_types)