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 "sysemu/char.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 } 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 /*
  49  * Protocol handshake done,
  50  * signal guest by an unsolicited DE irq.
  51  */
  52 static void TN3270_handshake_done(Terminal3270 *t)
  53 {
  54     CcwDevice *ccw_dev = CCW_DEVICE(t);
  55     SubchDev *sch = ccw_dev->sch;
  56
  57     t->handshake_done = true;
  58     sch->curr_status.scsw.dstat = SCSW_DSTAT_DEVICE_END;
  59     css_conditional_io_interrupt(sch);
  60 }
  61
  62 /*
  63  * Receive inbound data from socket.
  64  * For data given to guest, drop the data boundary IAC, IAC_EOR.
  65  * TODO:
  66  * Using "Reset" key on x3270 may result multiple commands in one packet.
  67  * This usually happens when the user meets a poor traffic of the network.
  68  * As of now, for such case, we simply terminate the connection,
  69  * and we should come back here later with a better solution.
  70  */
  71 static void terminal_read(void *opaque, const uint8_t *buf, int size)
  72 {
  73     Terminal3270 *t = opaque;
  74     CcwDevice *ccw_dev = CCW_DEVICE(t);
  75     SubchDev *sch = ccw_dev->sch;
  76     int end;
  77
  78     assert(size <= (INPUT_BUFFER_SIZE - t->in_len));
  79
  80     memcpy(&t->inv[t->in_len], buf, size);
  81     t->in_len += size;
  82     if (t->in_len < 2) {
  83         return;
  84     }
  85
  86     if (!t->handshake_done) {
  87         /*
  88          * Receiving Terminal Type is the last step of handshake.
  89          * The data format: IAC SB Terminal-Type IS <terminal type> IAC SE
  90          * The code for Terminal-Type is 0x18, for IS is 0.
  91          * Simply check the data format and mark handshake_done.
  92          */
  93         if (t->in_len > 6 && t->inv[2] == 0x18 && t->inv[3] == 0x0 &&
  94             t->inv[t->in_len - 2] == IAC && t->inv[t->in_len - 1] == IAC_SE) {
  95             TN3270_handshake_done(t);
  96             t->in_len = 0;
  97         }
  98         return;
  99     }
 100
 101     for (end = 0; end < t->in_len - 1; end++) {
 102         if (t->inv[end] == IAC && t->inv[end + 1] == IAC_EOR) {
 103             break;
 104         }
 105     }
 106     if (end == t->in_len - 2) {
 107         /* Data is valid for consuming. */
 108         t->in_len -= 2;
 109         sch->curr_status.scsw.dstat = SCSW_DSTAT_ATTENTION;
 110         css_conditional_io_interrupt(sch);
 111     } else if (end < t->in_len - 2) {
 112         /* "Reset" key is used. */
 113         qemu_chr_fe_disconnect(&t->chr);
 114     } else {
 115         /* Gathering data. */
 116         return;
 117     }
 118 }
 119
 120 static void terminal_init(EmulatedCcw3270Device *dev, Error **errp)
 121 {
 122     Terminal3270 *t = TERMINAL_3270(dev);
 123     static bool terminal_available;
 124
 125     if (terminal_available) {
 126         error_setg(errp, "Multiple 3270 terminals are not supported.");
 127         return;
 128     }
 129     terminal_available = true;
 130     qemu_chr_fe_set_handlers(&t->chr, terminal_can_read,
 131                              terminal_read, NULL, t, NULL, true);
 132 }
 133
 134 static int read_payload_3270(EmulatedCcw3270Device *dev, uint32_t cda,
 135                              uint16_t count)
 136 {
 137     Terminal3270 *t = TERMINAL_3270(dev);
 138     int len;
 139
 140     len = MIN(count, t->in_len);
 141     cpu_physical_memory_write(cda, t->inv, len);
 142     t->in_len -= len;
 143
 144     return len;
 145 }
 146
 147 /* TN3270 uses binary transmission, which needs escape IAC to IAC IAC */
 148 static int insert_IAC_escape_char(uint8_t *outv, int out_len)
 149 {
 150     int IAC_num = 0, new_out_len, i, j;
 151
 152     for (i = 0; i < out_len; i++) {
 153         if (outv[i] == IAC) {
 154             IAC_num++;
 155         }
 156     }
 157     if (IAC_num == 0) {
 158         return out_len;
 159     }
 160     new_out_len = out_len + IAC_num;
 161     for (i = out_len - 1, j = new_out_len - 1; j > i && i >= 0; i--, j--) {
 162         outv[j] = outv[i];
 163         if (outv[i] == IAC) {
 164             outv[--j] = IAC;
 165         }
 166     }
 167     return new_out_len;
 168 }
 169
 170 /*
 171  * Write 3270 outbound to socket.
 172  * Return the count of 3270 data field if succeeded, zero if failed.
 173  */
 174 static int write_payload_3270(EmulatedCcw3270Device *dev, uint8_t cmd,
 175                               uint32_t cda, uint16_t count)
 176 {
 177     Terminal3270 *t = TERMINAL_3270(dev);
 178     int retval = 0;
 179
 180     assert(count <= (OUTPUT_BUFFER_SIZE - 3) / 2);
 181
 182     if (!t->handshake_done) {
 183         /*
 184          * Before having finished 3270 negotiation,
 185          * sending outbound data is prohibited.
 186          */
 187         return 0;
 188     }
 189     if (!qemu_chr_fe_get_driver(&t->chr)) {
 190         /* We just say we consumed all data if there's no backend. */
 191         return count;
 192     }
 193     t->outv[0] = cmd;
 194     cpu_physical_memory_read(cda, &t->outv[1], count);
 195     t->out_len = count + 1;
 196
 197     t->out_len = insert_IAC_escape_char(t->outv, t->out_len);
 198     t->outv[t->out_len++] = IAC;
 199     t->outv[t->out_len++] = IAC_EOR;
 200
 201     retval = qemu_chr_fe_write_all(&t->chr, t->outv, t->out_len);
 202     return (retval <= 0) ? 0 : (retval - 3);
 203 }
 204
 205 static Property terminal_properties[] = {
 206     DEFINE_PROP_CHR("chardev", Terminal3270, chr),
 207     DEFINE_PROP_END_OF_LIST(),
 208 };
 209
 210 static void terminal_class_init(ObjectClass *klass, void *data)
 211 {
 212     DeviceClass *dc = DEVICE_CLASS(klass);
 213     EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
 214
 215     dc->props = terminal_properties;
 216     ck->init = terminal_init;
 217     ck->read_payload_3270 = read_payload_3270;
 218     ck->write_payload_3270 = write_payload_3270;
 219 }
 220
 221 static const TypeInfo ccw_terminal_info = {
 222     .name = TYPE_TERMINAL_3270,
 223     .parent = TYPE_EMULATED_CCW_3270,
 224     .instance_size = sizeof(Terminal3270),
 225     .class_init = terminal_class_init,
 226     .class_size = sizeof(EmulatedCcw3270Class),
 227 };
 228
 229 static void register_types(void)
 230 {
 231     type_register_static(&ccw_terminal_info);
 232 }
 233
 234 type_init(register_types)