src/websock.c

   1 /*
   2  * Copyright (C) 2016-2019 "IoT.bzh"
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 /*
  18  * This work is a far adaptation of apache-websocket:
  19  *   origin:  https://github.com/disconnect/apache-websocket
  20  *   commit:  cfaef071223f11ba016bff7e1e4b7c9e5df45b50
  21  *   Copyright 2010-2012 self.disconnect (APACHE-2)
  22  */
  23
  24 #include <stdlib.h>
  25 #include <stdint.h>
  26 #include <errno.h>
  27 #include <string.h>
  28 #include <sys/uio.h>
  29
  30 #include "websock.h"
  31
  32 #if !defined(WEBSOCKET_DEFAULT_MAXLENGTH)
  33 #  define WEBSOCKET_DEFAULT_MAXLENGTH 1048500  /* 76 less than 1M, probably enougth for headers */
  34 #endif
  35
  36 #define FRAME_GET_FIN(BYTE)         (((BYTE) >> 7) & 0x01)
  37 #define FRAME_GET_RSV1(BYTE)        (((BYTE) >> 6) & 0x01)
  38 #define FRAME_GET_RSV2(BYTE)        (((BYTE) >> 5) & 0x01)
  39 #define FRAME_GET_RSV3(BYTE)        (((BYTE) >> 4) & 0x01)
  40 #define FRAME_GET_OPCODE(BYTE)      ( (BYTE)       & 0x0F)
  41 #define FRAME_GET_MASK(BYTE)        (((BYTE) >> 7) & 0x01)
  42 #define FRAME_GET_PAYLOAD_LEN(BYTE) ( (BYTE)       & 0x7F)
  43
  44 #define FRAME_SET_FIN(BYTE)         (((BYTE) & 0x01) << 7)
  45 #define FRAME_SET_RSV1(BYTE)        (((BYTE) & 0x01) << 6)
  46 #define FRAME_SET_RSV2(BYTE)        (((BYTE) & 0x01) << 5)
  47 #define FRAME_SET_RSV3(BYTE)        (((BYTE) & 0x01) << 4)
  48 #define FRAME_SET_OPCODE(BYTE)      ((BYTE) & 0x0F)
  49 #define FRAME_SET_MASK(BYTE)        (((BYTE) & 0x01) << 7)
  50 #define FRAME_SET_LENGTH(X64, IDX)  (unsigned char)((sizeof(X64)) <= (IDX) ? 0 : (((X64) >> ((IDX)*8)) & 0xFF))
  51
  52 #define OPCODE_CONTINUATION 0x0
  53 #define OPCODE_TEXT         0x1
  54 #define OPCODE_BINARY       0x2
  55 #define OPCODE_CLOSE        0x8
  56 #define OPCODE_PING         0x9
  57 #define OPCODE_PONG         0xA
  58
  59 #define STATE_INIT    0
  60 #define STATE_START   1
  61 #define STATE_LENGTH  2
  62 #define STATE_DATA    3
  63
  64 static size_t default_maxlength = WEBSOCKET_DEFAULT_MAXLENGTH;
  65
  66 struct websock {
  67         int state;
  68         uint64_t maxlength;
  69         int lenhead, szhead;
  70         uint64_t length;
  71         uint32_t mask;
  72         unsigned char header[14];       /* 2 + 8 + 4 */
  73         const struct websock_itf *itf;
  74         void *closure;
  75 };
  76
  77 static ssize_t ws_writev(struct websock *ws, const struct iovec *iov, int iovcnt)
  78 {
  79         return ws->itf->writev(ws->closure, iov, iovcnt);
  80 }
  81
  82 static ssize_t ws_readv(struct websock *ws, const struct iovec *iov, int iovcnt)
  83 {
  84         return ws->itf->readv(ws->closure, iov, iovcnt);
  85 }
  86
  87 static ssize_t ws_read(struct websock *ws, void *buffer, size_t buffer_size)
  88 {
  89         struct iovec iov;
  90         iov.iov_base = buffer;
  91         iov.iov_len = buffer_size;
  92         return ws_readv(ws, &iov, 1);
  93 }
  94
  95 static int websock_send_internal_v(struct websock *ws, unsigned char first, const struct iovec *iovec, int count)
  96 {
  97         struct iovec iov[32];
  98         int i, j;
  99         size_t pos, size, len;
 100         ssize_t rc;
 101         unsigned char header[32];
 102
 103         /* checks count */
 104         if (count < 0 || (count + 1) > (int)(sizeof iov / sizeof * iov)) {
 105                 errno = EINVAL;
 106                 return -1;
 107         }
 108
 109         /* computes the size */
 110         size = 0;
 111         i = 1;
 112         for (j = 0 ; j < count ; j++) {
 113                 iov[i].iov_base = iovec[j].iov_base;
 114                 len = iovec[j].iov_len;
 115                 if (len != 0) {
 116                         iov[i].iov_len = len;
 117                         size += len;
 118                         i++;
 119                 }
 120         }
 121
 122         /* makes the header */
 123         pos = 0;
 124         header[pos++] = first;
 125         size = (uint64_t) size;
 126         if (size < 126) {
 127                 header[pos++] = FRAME_SET_MASK(0) | FRAME_SET_LENGTH(size, 0);
 128         } else {
 129                 if (size < 65536) {
 130                         header[pos++] = FRAME_SET_MASK(0) | 126;
 131                 } else {
 132                         header[pos++] = FRAME_SET_MASK(0) | 127;
 133                         header[pos++] = FRAME_SET_LENGTH(size, 7);
 134                         header[pos++] = FRAME_SET_LENGTH(size, 6);
 135                         header[pos++] = FRAME_SET_LENGTH(size, 5);
 136                         header[pos++] = FRAME_SET_LENGTH(size, 4);
 137                         header[pos++] = FRAME_SET_LENGTH(size, 3);
 138                         header[pos++] = FRAME_SET_LENGTH(size, 2);
 139                 }
 140                 header[pos++] = FRAME_SET_LENGTH(size, 1);
 141                 header[pos++] = FRAME_SET_LENGTH(size, 0);
 142         }
 143
 144         /* allocates the vec */
 145         iov[0].iov_base = header;
 146         iov[0].iov_len = pos;
 147         rc = ws_writev(ws, iov, i);
 148
 149         return rc < 0 ? -1 : 0;
 150 }
 151
 152 static int websock_send_internal(struct websock *ws, unsigned char first, const void *buffer, size_t size)
 153 {
 154         struct iovec iov;
 155
 156         iov.iov_base = (void *)buffer;
 157         iov.iov_len = size;
 158         return websock_send_internal_v(ws, first, &iov, 1);
 159 }
 160
 161 static inline int websock_send_v(struct websock *ws, int last, int rsv1, int rsv2, int rsv3, int opcode, const struct iovec *iovec, int count)
 162 {
 163         unsigned char first = (unsigned char)(FRAME_SET_FIN(last)
 164                                 | FRAME_SET_RSV1(rsv1)
 165                                 | FRAME_SET_RSV1(rsv2)
 166                                 | FRAME_SET_RSV1(rsv3)
 167                                 | FRAME_SET_OPCODE(opcode));
 168         return websock_send_internal_v(ws, first, iovec, count);
 169 }
 170
 171 static inline int websock_send(struct websock *ws, int last, int rsv1, int rsv2, int rsv3, int opcode, const void *buffer, size_t size)
 172 {
 173         unsigned char first = (unsigned char)(FRAME_SET_FIN(last)
 174                                 | FRAME_SET_RSV1(rsv1)
 175                                 | FRAME_SET_RSV1(rsv2)
 176                                 | FRAME_SET_RSV1(rsv3)
 177                                 | FRAME_SET_OPCODE(opcode));
 178         return websock_send_internal(ws, first, buffer, size);
 179 }
 180
 181 int websock_close_empty(struct websock *ws)
 182 {
 183         return websock_close(ws, WEBSOCKET_CODE_NOT_SET, NULL, 0);
 184 }
 185
 186 int websock_close(struct websock *ws, uint16_t code, const void *data, size_t length)
 187 {
 188         unsigned char buffer[2];
 189         struct iovec iov[2];
 190
 191         if (code == WEBSOCKET_CODE_NOT_SET && length == 0)
 192                 return websock_send(ws, 1, 0, 0, 0, OPCODE_CLOSE, NULL, 0);
 193
 194         /* checks the length */
 195         if (length > 123) {
 196                 errno = EINVAL;
 197                 return -1;
 198         }
 199
 200         /* prepare the buffer */
 201         buffer[0] = (unsigned char)((code >> 8) & 0xFF);
 202         buffer[1] = (unsigned char)(code & 0xFF);
 203
 204         /* Send server-side closing handshake */
 205         iov[0].iov_base = (void *)buffer;
 206         iov[0].iov_len = 2;
 207         iov[1].iov_base = (void *)data;
 208         iov[1].iov_len = length;
 209         return websock_send_v(ws, 1, 0, 0, 0, OPCODE_CLOSE, iov, 2);
 210 }
 211
 212 int websock_ping(struct websock *ws, const void *data, size_t length)
 213 {
 214         /* checks the length */
 215         if (length > 125) {
 216                 errno = EINVAL;
 217                 return -1;
 218         }
 219
 220         return websock_send(ws, 1, 0, 0, 0, OPCODE_PING, data, length);
 221 }
 222
 223 int websock_pong(struct websock *ws, const void *data, size_t length)
 224 {
 225         /* checks the length */
 226         if (length > 125) {
 227                 errno = EINVAL;
 228                 return -1;
 229         }
 230
 231         return websock_send(ws, 1, 0, 0, 0, OPCODE_PONG, data, length);
 232 }
 233
 234 int websock_text(struct websock *ws, int last, const void *text, size_t length)
 235 {
 236         return websock_send(ws, last, 0, 0, 0, OPCODE_TEXT, text, length);
 237 }
 238
 239 int websock_text_v(struct websock *ws, int last, const struct iovec *iovec, int count)
 240 {
 241         return websock_send_v(ws, last, 0, 0, 0, OPCODE_TEXT, iovec, count);
 242 }
 243
 244 int websock_binary(struct websock *ws, int last, const void *data, size_t length)
 245 {
 246         return websock_send(ws, last, 0, 0, 0, OPCODE_BINARY, data, length);
 247 }
 248
 249 int websock_binary_v(struct websock *ws, int last, const struct iovec *iovec, int count)
 250 {
 251         return websock_send_v(ws, last, 0, 0, 0, OPCODE_BINARY, iovec, count);
 252 }
 253
 254 int websock_continue(struct websock *ws, int last, const void *data, size_t length)
 255 {
 256         return websock_send(ws, last, 0, 0, 0, OPCODE_CONTINUATION, data, length);
 257 }
 258
 259 int websock_continue_v(struct websock *ws, int last, const struct iovec *iovec, int count)
 260 {
 261         return websock_send_v(ws, last, 0, 0, 0, OPCODE_CONTINUATION, iovec, count);
 262 }
 263
 264 int websock_error(struct websock *ws, uint16_t code, const void *data, size_t size)
 265 {
 266         int rc = websock_close(ws, code, data, size);
 267         if (ws->itf->on_error != NULL)
 268                 ws->itf->on_error(ws->closure, code, data, size);
 269         return rc;
 270 }
 271
 272 static int read_header(struct websock *ws)
 273 {
 274         if (ws->lenhead < ws->szhead) {
 275                 ssize_t rbc =
 276                     ws_read(ws, &ws->header[ws->lenhead], (size_t)(ws->szhead - ws->lenhead));
 277                 if (rbc < 0)
 278                         return -1;
 279                 ws->lenhead += (int)rbc;
 280         }
 281         return 0;
 282 }
 283
 284 static int check_control_header(struct websock *ws)
 285 {
 286         /* sanity checks */
 287         if (FRAME_GET_RSV1(ws->header[0]) != 0)
 288                 return 0;
 289         if (FRAME_GET_RSV2(ws->header[0]) != 0)
 290                 return 0;
 291         if (FRAME_GET_RSV3(ws->header[0]) != 0)
 292                 return 0;
 293         if (FRAME_GET_PAYLOAD_LEN(ws->header[1]) > 125)
 294                 return 0;
 295         if (FRAME_GET_OPCODE(ws->header[0]) == OPCODE_CLOSE)
 296                 return FRAME_GET_PAYLOAD_LEN(ws->header[1]) != 1;
 297         return 1;
 298 }
 299
 300 int websock_dispatch(struct websock *ws, int loop)
 301 {
 302         uint16_t code;
 303 loop:
 304         switch (ws->state) {
 305         case STATE_INIT:
 306                 ws->lenhead = 0;
 307                 ws->szhead = 2;
 308                 ws->state = STATE_START;
 309                 /*@fallthrough@*/
 310
 311         case STATE_START:
 312                 /* read the header */
 313                 if (read_header(ws))
 314                         return -1;
 315                 else if (ws->lenhead < ws->szhead)
 316                         return 0;
 317                 /* fast track */
 318                 switch (FRAME_GET_OPCODE(ws->header[0])) {
 319                 case OPCODE_CONTINUATION:
 320                 case OPCODE_TEXT:
 321                 case OPCODE_BINARY:
 322                         break;
 323                 case OPCODE_CLOSE:
 324                         if (!check_control_header(ws))
 325                                 goto protocol_error;
 326                         if (FRAME_GET_PAYLOAD_LEN(ws->header[1]))
 327                                 ws->szhead += 2;
 328                         break;
 329                 case OPCODE_PING:
 330                 case OPCODE_PONG:
 331                         if (!check_control_header(ws))
 332                                 goto protocol_error;
 333                 default:
 334                         break;
 335                 }
 336                 /* update heading size */
 337                 switch (FRAME_GET_PAYLOAD_LEN(ws->header[1])) {
 338                 case 127:
 339                         ws->szhead += 6;
 340                         /*@fallthrough@*/
 341                 case 126:
 342                         ws->szhead += 2;
 343                         /*@fallthrough@*/
 344                 default:
 345                         ws->szhead += 4 * FRAME_GET_MASK(ws->header[1]);
 346                 }
 347                 ws->state = STATE_LENGTH;
 348                 /*@fallthrough@*/
 349
 350         case STATE_LENGTH:
 351                 /* continue to read the header */
 352                 if (read_header(ws))
 353                         return -1;
 354                 else if (ws->lenhead < ws->szhead)
 355                         return 0;
 356
 357                 /* compute length */
 358                 switch (FRAME_GET_PAYLOAD_LEN(ws->header[1])) {
 359                 case 127:
 360                         ws->length = (((uint64_t) ws->header[2]) << 56)
 361                             | (((uint64_t) ws->header[3]) << 48)
 362                             | (((uint64_t) ws->header[4]) << 40)
 363                             | (((uint64_t) ws->header[5]) << 32)
 364                             | (((uint64_t) ws->header[6]) << 24)
 365                             | (((uint64_t) ws->header[7]) << 16)
 366                             | (((uint64_t) ws->header[8]) << 8)
 367                             | (uint64_t) ws->header[9];
 368                         break;
 369                 case 126:
 370                         ws->length = (((uint64_t) ws->header[2]) << 8)
 371                             | (uint64_t) ws->header[3];
 372                         break;
 373                 default:
 374                         ws->length = FRAME_GET_PAYLOAD_LEN(ws->header[1]);
 375                         break;
 376                 }
 377                 if (FRAME_GET_OPCODE(ws->header[0]) == OPCODE_CLOSE && ws->length != 0)
 378                         ws->length -= 2;
 379                 if (ws->length > ws->maxlength)
 380                         goto too_long_error;
 381
 382                 /* compute mask */
 383                 if (FRAME_GET_MASK(ws->header[1])) {
 384                         ((unsigned char *)&ws->mask)[0] = ws->header[ws->szhead - 4];
 385                         ((unsigned char *)&ws->mask)[1] = ws->header[ws->szhead - 3];
 386                         ((unsigned char *)&ws->mask)[2] = ws->header[ws->szhead - 2];
 387                         ((unsigned char *)&ws->mask)[3] = ws->header[ws->szhead - 1];
 388                 } else
 389                         ws->mask = 0;
 390
 391                 /* all heading fields are known, process */
 392                 ws->state = STATE_DATA;
 393                 if (ws->itf->on_extension != NULL) {
 394                         if (ws->itf->on_extension(ws->closure,
 395                                         FRAME_GET_FIN(ws->header[0]),
 396                                         FRAME_GET_RSV1(ws->header[0]),
 397                                         FRAME_GET_RSV2(ws->header[0]),
 398                                         FRAME_GET_RSV3(ws->header[0]),
 399                                         FRAME_GET_OPCODE(ws->header[0]),
 400                                         (size_t) ws->length)) {
 401                                 return 0;
 402                         }
 403                 }
 404
 405                 /* not an extension case */
 406                 if (FRAME_GET_RSV1(ws->header[0]) != 0)
 407                         goto protocol_error;
 408                 if (FRAME_GET_RSV2(ws->header[0]) != 0)
 409                         goto protocol_error;
 410                 if (FRAME_GET_RSV3(ws->header[0]) != 0)
 411                         goto protocol_error;
 412
 413                 /* handle */
 414                 switch (FRAME_GET_OPCODE(ws->header[0])) {
 415                 case OPCODE_CONTINUATION:
 416                         ws->itf->on_continue(ws->closure,
 417                                              FRAME_GET_FIN(ws->header[0]),
 418                                              (size_t) ws->length);
 419                         if (!loop)
 420                                 return 0;
 421                         break;
 422                 case OPCODE_TEXT:
 423                         ws->itf->on_text(ws->closure,
 424                                          FRAME_GET_FIN(ws->header[0]),
 425                                          (size_t) ws->length);
 426                         if (!loop)
 427                                 return 0;
 428                         break;
 429                 case OPCODE_BINARY:
 430                         ws->itf->on_binary(ws->closure,
 431                                            FRAME_GET_FIN(ws->header[0]),
 432                                            (size_t) ws->length);
 433                         if (!loop)
 434                                 return 0;
 435                         break;
 436                 case OPCODE_CLOSE:
 437                         if (ws->length == 0)
 438                                 code = WEBSOCKET_CODE_NOT_SET;
 439                         else {
 440                                 code = (uint16_t)(ws->header[ws->szhead - 2] & 0xff);
 441                                 code = (uint16_t)(code << 8);
 442                                 code = (uint16_t)(code | (uint16_t)(ws->header[ws->szhead - 1] & 0xff));
 443                         }
 444                         ws->itf->on_close(ws->closure, code, (size_t) ws->length);
 445                         return 0;
 446                 case OPCODE_PING:
 447                         if (ws->itf->on_ping)
 448                                 ws->itf->on_ping(ws->closure, ws->length);
 449                         else {
 450                                 websock_drop(ws);
 451                                 websock_pong(ws, NULL, 0);
 452                         }
 453                         ws->state = STATE_INIT;
 454                         if (!loop)
 455                                 return 0;
 456                         break;
 457                 case OPCODE_PONG:
 458                         if (ws->itf->on_pong)
 459                                 ws->itf->on_pong(ws->closure, ws->length);
 460                         else
 461                                 websock_drop(ws);
 462                         ws->state = STATE_INIT;
 463                         if (!loop)
 464                                 return 0;
 465                         break;
 466                 default:
 467                         goto protocol_error;
 468                 }
 469                 break;
 470
 471         case STATE_DATA:
 472                 if (ws->length)
 473                         return 0;
 474                 ws->state = STATE_INIT;
 475                 break;
 476         }
 477         goto loop;
 478
 479  too_long_error:
 480         websock_error(ws, WEBSOCKET_CODE_MESSAGE_TOO_LARGE, NULL, 0);
 481         return 0;
 482
 483  protocol_error:
 484         websock_error(ws, WEBSOCKET_CODE_PROTOCOL_ERROR, NULL, 0);
 485         return 0;
 486 }
 487
 488 static void unmask(struct websock * ws, void *buffer, size_t size)
 489 {
 490         uint32_t mask, *b32;
 491         uint8_t m, *b8;
 492
 493         mask = ws->mask;
 494         b8 = buffer;
 495         while (size && ((sizeof(uint32_t) - 1) & (uintptr_t) b8)) {
 496                 m = ((uint8_t *) & mask)[0];
 497                 ((uint8_t *) & mask)[0] = ((uint8_t *) & mask)[1];
 498                 ((uint8_t *) & mask)[1] = ((uint8_t *) & mask)[2];
 499                 ((uint8_t *) & mask)[2] = ((uint8_t *) & mask)[3];
 500                 ((uint8_t *) & mask)[3] = m;
 501                 *b8++ ^= m;
 502                 size--;
 503         }
 504         b32 = (uint32_t *) b8;
 505         while (size >= sizeof(uint32_t)) {
 506                 *b32++ ^= mask;
 507                 size -= sizeof(uint32_t);
 508         }
 509         b8 = (uint8_t *) b32;
 510         while (size) {
 511                 m = ((uint8_t *) & mask)[0];
 512                 ((uint8_t *) & mask)[0] = ((uint8_t *) & mask)[1];
 513                 ((uint8_t *) & mask)[1] = ((uint8_t *) & mask)[2];
 514                 ((uint8_t *) & mask)[2] = ((uint8_t *) & mask)[3];
 515                 ((uint8_t *) & mask)[3] = m;
 516                 *b8++ ^= m;
 517                 size--;
 518         }
 519         ws->mask = mask;
 520 }
 521
 522 ssize_t websock_read(struct websock * ws, void *buffer, size_t size)
 523 {
 524         ssize_t rc;
 525
 526         if (ws->state != STATE_DATA)
 527                 return 0;
 528
 529         if (size > ws->length)
 530                 size = (size_t) ws->length;
 531
 532         rc = ws_read(ws, buffer, size);
 533         if (rc > 0) {
 534                 size = (size_t) rc;
 535                 ws->length -= size;
 536
 537                 if (ws->mask != 0)
 538                         unmask(ws, buffer, size);
 539         }
 540         return rc;
 541 }
 542
 543 int websock_drop(struct websock *ws)
 544 {
 545         char buffer[8000];
 546
 547         while (ws->length)
 548                 if (websock_read(ws, buffer, sizeof buffer) < 0)
 549                         return -1;
 550         return 0;
 551 }
 552
 553 struct websock *websock_create_v13(const struct websock_itf *itf, void *closure)
 554 {
 555         struct websock *result = calloc(1, sizeof *result);
 556         if (result) {
 557                 result->itf = itf;
 558                 result->closure = closure;
 559                 result->maxlength = default_maxlength;
 560         }
 561         return result;
 562 }
 563
 564 void websock_destroy(struct websock *ws)
 565 {
 566         free(ws);
 567 }
 568
 569 void websock_set_default_max_length(size_t maxlen)
 570 {
 571         default_maxlength = maxlen;
 572 }
 573
 574 void websock_set_max_length(struct websock *ws, size_t maxlen)
 575 {
 576         ws->maxlength = (uint64_t)maxlen;
 577 }
 578
 579 const char *websocket_explain_error(uint16_t code)
 580 {
 581         static const char *msgs[] = {
 582                 "OK",                /* 1000 */
 583                 "GOING_AWAY",        /* 1001 */
 584                 "PROTOCOL_ERROR",    /* 1002 */
 585                 "CANT_ACCEPT",       /* 1003 */
 586                 "RESERVED",          /* 1004 */
 587                 "NOT_SET",           /* 1005 */
 588                 "ABNORMAL",          /* 1006 */
 589                 "INVALID_UTF8",      /* 1007 */
 590                 "POLICY_VIOLATION",  /* 1008 */
 591                 "MESSAGE_TOO_LARGE", /* 1009 */
 592                 "EXPECT_EXTENSION",  /* 1010 */
 593                 "INTERNAL_ERROR",    /* 1011 */
 594         };
 595         if (code < 1000 || (code - 1000) >= (sizeof msgs / sizeof *msgs))
 596                 return "?";
 597         return msgs[code - 1000];
 598 }