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     GSource *timer_src;
  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_src) {
  51         g_source_destroy(t->timer_src);
  52         g_source_unref(t->timer_src);
  53         t->timer_src = NULL;
  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_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000,
 104                                            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_src = qemu_chr_timeout_add_ms(t->chr.chr, 600 * 1000,
 164                                                send_timing_mark_cb, t);
 165         break;
 166     case CHR_EVENT_CLOSED:
 167         sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
 168         css_conditional_io_interrupt(sch);
 169         break;
 170     }
 171 }
 172
 173 static void terminal_init(EmulatedCcw3270Device *dev, Error **errp)
 174 {
 175     Terminal3270 *t = TERMINAL_3270(dev);
 176     static bool terminal_available;
 177
 178     if (terminal_available) {
 179         error_setg(errp, "Multiple 3270 terminals are not supported.");
 180         return;
 181     }
 182     terminal_available = true;
 183     qemu_chr_fe_set_handlers(&t->chr, terminal_can_read,
 184                              terminal_read, chr_event, NULL, t, NULL, true);
 185 }
 186
 187 static inline CcwDataStream *get_cds(Terminal3270 *t)
 188 {
 189     return &(CCW_DEVICE(&t->cdev)->sch->cds);
 190 }
 191
 192 static int read_payload_3270(EmulatedCcw3270Device *dev)
 193 {
 194     Terminal3270 *t = TERMINAL_3270(dev);
 195     int len;
 196
 197     len = MIN(ccw_dstream_avail(get_cds(t)), t->in_len);
 198     ccw_dstream_write_buf(get_cds(t), t->inv, len);
 199     t->in_len -= len;
 200
 201     return len;
 202 }
 203
 204 /* TN3270 uses binary transmission, which needs escape IAC to IAC IAC */
 205 static int insert_IAC_escape_char(uint8_t *outv, int out_len)
 206 {
 207     int IAC_num = 0, new_out_len, i, j;
 208
 209     for (i = 0; i < out_len; i++) {
 210         if (outv[i] == IAC) {
 211             IAC_num++;
 212         }
 213     }
 214     if (IAC_num == 0) {
 215         return out_len;
 216     }
 217     new_out_len = out_len + IAC_num;
 218     for (i = out_len - 1, j = new_out_len - 1; j > i && i >= 0; i--, j--) {
 219         outv[j] = outv[i];
 220         if (outv[i] == IAC) {
 221             outv[--j] = IAC;
 222         }
 223     }
 224     return new_out_len;
 225 }
 226
 227 /*
 228  * Write 3270 outbound to socket.
 229  * Return the count of 3270 data field if succeeded, zero if failed.
 230  */
 231 static int write_payload_3270(EmulatedCcw3270Device *dev, uint8_t cmd)
 232 {
 233     Terminal3270 *t = TERMINAL_3270(dev);
 234     int retval = 0;
 235     int count = ccw_dstream_avail(get_cds(t));
 236     int bound = (OUTPUT_BUFFER_SIZE - 3) / 2;
 237     int len = MIN(count, bound);
 238     int out_len = 0;
 239
 240     if (!t->handshake_done) {
 241         if (!(t->outv[0] == IAC && t->outv[1] != IAC)) {
 242             /*
 243              * Before having finished 3270 negotiation,
 244              * sending outbound data except protocol options is prohibited.
 245              */
 246             return 0;
 247         }
 248     }
 249     if (!qemu_chr_fe_backend_connected(&t->chr)) {
 250         /* We just say we consumed all data if there's no backend. */
 251         return count;
 252     }
 253
 254     t->outv[out_len++] = cmd;
 255     do {
 256         ccw_dstream_read_buf(get_cds(t), &t->outv[out_len], len);
 257         count = ccw_dstream_avail(get_cds(t));
 258         out_len += len;
 259
 260         out_len = insert_IAC_escape_char(t->outv, out_len);
 261         if (!count) {
 262             t->outv[out_len++] = IAC;
 263             t->outv[out_len++] = IAC_EOR;
 264         }
 265         retval = qemu_chr_fe_write_all(&t->chr, t->outv, out_len);
 266         len = MIN(count, bound);
 267         out_len = 0;
 268     } while (len && retval >= 0);
 269     return (retval <= 0) ? 0 : get_cds(t)->count;
 270 }
 271
 272 static Property terminal_properties[] = {
 273     DEFINE_PROP_CHR("chardev", Terminal3270, chr),
 274     DEFINE_PROP_END_OF_LIST(),
 275 };
 276
 277 static const VMStateDescription terminal3270_vmstate = {
 278     .name = TYPE_TERMINAL_3270,
 279     .unmigratable = 1,
 280 };
 281
 282 static void terminal_class_init(ObjectClass *klass, void *data)
 283 {
 284     DeviceClass *dc = DEVICE_CLASS(klass);
 285     EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
 286
 287     dc->props = terminal_properties;
 288     dc->vmsd = &terminal3270_vmstate;
 289     ck->init = terminal_init;
 290     ck->read_payload_3270 = read_payload_3270;
 291     ck->write_payload_3270 = write_payload_3270;
 292 }
 293
 294 static const TypeInfo ccw_terminal_info = {
 295     .name = TYPE_TERMINAL_3270,
 296     .parent = TYPE_EMULATED_CCW_3270,
 297     .instance_size = sizeof(Terminal3270),
 298     .class_init = terminal_class_init,
 299     .class_size = sizeof(EmulatedCcw3270Class),
 300 };
 301
 302 static void register_types(void)
 303 {
 304     type_register_static(&ccw_terminal_info);
 305 }
 306
 307 type_init(register_types)