lib/tevent/echo_server.c

   1 /**
   2  ** NOTE! The following liberal license applies to this sample file only.
   3  ** This does NOT imply that all of Samba is released under this license.
   4  **
   5  ** This file is meant as a starting point for libtevent users to be used
   6  ** in any program linking against the LGPL licensed libtevent.
   7  **/
   8
   9 /*
  10  * This file is being made available by the Samba Team under the following
  11  * license:
  12  *
  13  * Permission to use, copy, modify, and distribute this sample file for any
  14  * purpose is hereby granted without fee.
  15  *
  16  * This work is distributed in the hope that it will be useful, but
  17  * WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  19  */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <netinet/in.h>
  25 #include <sys/types.h>
  26 #include <sys/socket.h>
  27 #include <errno.h>
  28 #include <unistd.h>
  29 #include "tevent.h"
  30 #include "talloc.h"
  31
  32 /**
  33  * @brief Helper function to get a useful unix error from tevent_req
  34  */
  35
  36 static bool tevent_req_is_unix_error(struct tevent_req *req, int *perrno)
  37 {
  38         enum tevent_req_state state;
  39         uint64_t err;
  40
  41         if (!tevent_req_is_error(req, &state, &err)) {
  42                 return false;
  43         }
  44         switch (state) {
  45         case TEVENT_REQ_TIMED_OUT:
  46                 *perrno = ETIMEDOUT;
  47                 break;
  48         case TEVENT_REQ_NO_MEMORY:
  49                 *perrno = ENOMEM;
  50                 break;
  51         case TEVENT_REQ_USER_ERROR:
  52                 *perrno = err;
  53                 break;
  54         default:
  55                 *perrno = EINVAL;
  56                 break;
  57         }
  58         return true;
  59 }
  60
  61 /**
  62  * @brief Wrapper around accept(2)
  63  */
  64
  65 struct accept_state {
  66         struct tevent_fd *fde;
  67         int listen_sock;
  68         socklen_t addrlen;
  69         struct sockaddr addr;
  70         int sock;
  71 };
  72
  73 static void accept_handler(struct tevent_context *ev, struct tevent_fd *fde,
  74                            uint16_t flags, void *private_data);
  75
  76 static struct tevent_req *accept_send(TALLOC_CTX *mem_ctx,
  77                                       struct tevent_context *ev,
  78                                       int listen_sock)
  79 {
  80         struct tevent_req *req;
  81         struct accept_state *state;
  82
  83         req = tevent_req_create(mem_ctx, &state, struct accept_state);
  84         if (req == NULL) {
  85                 return NULL;
  86         }
  87
  88         state->listen_sock = listen_sock;
  89
  90         state->fde = tevent_add_fd(ev, state, listen_sock, TEVENT_FD_READ,
  91                                    accept_handler, req);
  92         if (tevent_req_nomem(state->fde, req)) {
  93                 return tevent_req_post(req, ev);
  94         }
  95         return req;
  96 }
  97
  98 static void accept_handler(struct tevent_context *ev, struct tevent_fd *fde,
  99                            uint16_t flags, void *private_data)
 100 {
 101         struct tevent_req *req = talloc_get_type_abort(
 102                 private_data, struct tevent_req);
 103         struct accept_state *state = tevent_req_data(req, struct accept_state);
 104         int ret;
 105
 106         TALLOC_FREE(state->fde);
 107
 108         if ((flags & TEVENT_FD_READ) == 0) {
 109                 tevent_req_error(req, EIO);
 110                 return;
 111         }
 112         state->addrlen = sizeof(state->addr);
 113
 114         ret = accept(state->listen_sock, &state->addr, &state->addrlen);
 115         if (ret == -1) {
 116                 tevent_req_error(req, errno);
 117                 return;
 118         }
 119         state->sock = ret;
 120         tevent_req_done(req);
 121 }
 122
 123 static int accept_recv(struct tevent_req *req, struct sockaddr *paddr,
 124                        socklen_t *paddrlen, int *perr)
 125 {
 126         struct accept_state *state = tevent_req_data(req, struct accept_state);
 127         int err;
 128
 129         if (tevent_req_is_unix_error(req, &err)) {
 130                 if (perr != NULL) {
 131                         *perr = err;
 132                 }
 133                 return -1;
 134         }
 135         if (paddr != NULL) {
 136                 *paddr = state->addr;
 137         }
 138         if (paddrlen != NULL) {
 139                 *paddrlen = state->addrlen;
 140         }
 141         return state->sock;
 142 }
 143
 144 /**
 145  * @brief Wrapper around read(2)
 146  */
 147
 148 struct read_state {
 149         struct tevent_fd *fde;
 150         int fd;
 151         void *buf;
 152         size_t count;
 153
 154         ssize_t nread;
 155 };
 156
 157 static void read_handler(struct tevent_context *ev, struct tevent_fd *fde,
 158                          uint16_t flags, void *private_data);
 159
 160 static struct tevent_req *read_send(TALLOC_CTX *mem_ctx,
 161                                     struct tevent_context *ev,
 162                                     int fd, void *buf, size_t count)
 163 {
 164         struct tevent_req *req;
 165         struct read_state *state;
 166
 167         req = tevent_req_create(mem_ctx, &state, struct read_state);
 168         if (req == NULL) {
 169                 return NULL;
 170         }
 171
 172         state->fd = fd;
 173         state->buf = buf;
 174         state->count = count;
 175
 176         state->fde = tevent_add_fd(ev, state, fd, TEVENT_FD_READ,
 177                                    read_handler, req);
 178         if (tevent_req_nomem(state->fde, req)) {
 179                 return tevent_req_post(req, ev);
 180         }
 181         return req;
 182 }
 183
 184 static void read_handler(struct tevent_context *ev, struct tevent_fd *fde,
 185                          uint16_t flags, void *private_data)
 186 {
 187         struct tevent_req *req = talloc_get_type_abort(
 188                 private_data, struct tevent_req);
 189         struct read_state *state = tevent_req_data(req, struct read_state);
 190         ssize_t ret;
 191
 192         TALLOC_FREE(state->fde);
 193
 194         if ((flags & TEVENT_FD_READ) == 0) {
 195                 tevent_req_error(req, EIO);
 196                 return;
 197         }
 198
 199         ret = read(state->fd, state->buf, state->count);
 200         if (ret == -1) {
 201                 tevent_req_error(req, errno);
 202                 return;
 203         }
 204         state->nread = ret;
 205         tevent_req_done(req);
 206 }
 207
 208 static ssize_t read_recv(struct tevent_req *req, int *perr)
 209 {
 210         struct read_state *state = tevent_req_data(req, struct read_state);
 211         int err;
 212
 213         if (tevent_req_is_unix_error(req, &err)) {
 214                 if (perr != NULL) {
 215                         *perr = err;
 216                 }
 217                 return -1;
 218         }
 219         return state->nread;
 220 }
 221
 222 /**
 223  * @brief Wrapper around write(2)
 224  */
 225
 226 struct write_state {
 227         struct tevent_fd *fde;
 228         int fd;
 229         const void *buf;
 230         size_t count;
 231
 232         ssize_t nwritten;
 233 };
 234
 235 static void write_handler(struct tevent_context *ev, struct tevent_fd *fde,
 236                          uint16_t flags, void *private_data);
 237
 238 static struct tevent_req *write_send(TALLOC_CTX *mem_ctx,
 239                                     struct tevent_context *ev,
 240                                     int fd, const void *buf, size_t count)
 241 {
 242         struct tevent_req *req;
 243         struct write_state *state;
 244
 245         req = tevent_req_create(mem_ctx, &state, struct write_state);
 246         if (req == NULL) {
 247                 return NULL;
 248         }
 249
 250         state->fd = fd;
 251         state->buf = buf;
 252         state->count = count;
 253
 254         state->fde = tevent_add_fd(ev, state, fd, TEVENT_FD_WRITE,
 255                                    write_handler, req);
 256         if (tevent_req_nomem(state->fde, req)) {
 257                 return tevent_req_post(req, ev);
 258         }
 259         return req;
 260 }
 261
 262 static void write_handler(struct tevent_context *ev, struct tevent_fd *fde,
 263                          uint16_t flags, void *private_data)
 264 {
 265         struct tevent_req *req = talloc_get_type_abort(
 266                 private_data, struct tevent_req);
 267         struct write_state *state = tevent_req_data(req, struct write_state);
 268         ssize_t ret;
 269
 270         TALLOC_FREE(state->fde);
 271
 272         if ((flags & TEVENT_FD_WRITE) == 0) {
 273                 tevent_req_error(req, EIO);
 274                 return;
 275         }
 276
 277         ret = write(state->fd, state->buf, state->count);
 278         if (ret == -1) {
 279                 tevent_req_error(req, errno);
 280                 return;
 281         }
 282         state->nwritten = ret;
 283         tevent_req_done(req);
 284 }
 285
 286 static ssize_t write_recv(struct tevent_req *req, int *perr)
 287 {
 288         struct write_state *state = tevent_req_data(req, struct write_state);
 289         int err;
 290
 291         if (tevent_req_is_unix_error(req, &err)) {
 292                 if (perr != NULL) {
 293                         *perr = err;
 294                 }
 295                 return -1;
 296         }
 297         return state->nwritten;
 298 }
 299
 300 /**
 301  * @brief Wrapper function that deals with short writes
 302  */
 303
 304 struct writeall_state {
 305         struct tevent_context *ev;
 306         int fd;
 307         const void *buf;
 308         size_t count;
 309         size_t nwritten;
 310 };
 311
 312 static void writeall_done(struct tevent_req *subreq);
 313
 314 static struct tevent_req *writeall_send(TALLOC_CTX *mem_ctx,
 315                                         struct tevent_context *ev,
 316                                         int fd, const void *buf, size_t count)
 317 {
 318         struct tevent_req *req, *subreq;
 319         struct writeall_state *state;
 320
 321         req = tevent_req_create(mem_ctx, &state, struct writeall_state);
 322         if (req == NULL) {
 323                 return NULL;
 324         }
 325         state->ev = ev;
 326         state->fd = fd;
 327         state->buf = buf;
 328         state->count = count;
 329         state->nwritten = 0;
 330
 331         subreq = write_send(state, state->ev, state->fd,
 332                             ((char *)state->buf)+state->nwritten,
 333                             state->count - state->nwritten);
 334         if (tevent_req_nomem(subreq, req)) {
 335                 return tevent_req_post(req, ev);
 336         }
 337         tevent_req_set_callback(subreq, writeall_done, req);
 338         return req;
 339 }
 340
 341 static void writeall_done(struct tevent_req *subreq)
 342 {
 343         struct tevent_req *req = tevent_req_callback_data(
 344                 subreq, struct tevent_req);
 345         struct writeall_state *state = tevent_req_data(
 346                 req, struct writeall_state);
 347         ssize_t nwritten;
 348         int err = 0;
 349
 350         nwritten = write_recv(subreq, &err);
 351         TALLOC_FREE(subreq);
 352         if (nwritten == -1) {
 353                 tevent_req_error(req, err);
 354                 return;
 355         }
 356
 357         state->nwritten += nwritten;
 358
 359         if (state->nwritten < state->count) {
 360                 subreq = write_send(state, state->ev, state->fd,
 361                                     ((char *)state->buf)+state->nwritten,
 362                                     state->count - state->nwritten);
 363                 if (tevent_req_nomem(subreq, req)) {
 364                         return;
 365                 }
 366                 tevent_req_set_callback(subreq, writeall_done, req);
 367                 return;
 368         }
 369         tevent_req_done(req);
 370 }
 371
 372 static ssize_t writeall_recv(struct tevent_req *req, int *perr)
 373 {
 374         struct writeall_state *state = tevent_req_data(
 375                 req, struct writeall_state);
 376         int err;
 377
 378         if (tevent_req_is_unix_error(req, &err)) {
 379                 if (perr != NULL) {
 380                         *perr = err;
 381                 }
 382                 return -1;
 383         }
 384         return state->nwritten;
 385 }
 386
 387 /**
 388  * @brief Async echo handler code dealing with one client
 389  */
 390
 391 struct echo_state {
 392         struct tevent_context *ev;
 393         int fd;
 394         uint8_t *buf;
 395 };
 396
 397 static int echo_state_destructor(struct echo_state *s);
 398 static void echo_read_done(struct tevent_req *subreq);
 399 static void echo_writeall_done(struct tevent_req *subreq);
 400
 401 static struct tevent_req *echo_send(TALLOC_CTX *mem_ctx,
 402                                     struct tevent_context *ev,
 403                                     int fd, size_t bufsize)
 404 {
 405         struct tevent_req *req, *subreq;
 406         struct echo_state *state;
 407
 408         req = tevent_req_create(mem_ctx, &state, struct echo_state);
 409         if (req == NULL) {
 410                 return NULL;
 411         }
 412         state->ev = ev;
 413         state->fd = fd;
 414
 415         talloc_set_destructor(state, echo_state_destructor);
 416
 417         state->buf = talloc_array(state, uint8_t, bufsize);
 418         if (tevent_req_nomem(state->buf, req)) {
 419                 return tevent_req_post(req, ev);
 420         }
 421
 422         subreq = read_send(state, state->ev, state->fd,
 423                            state->buf, talloc_get_size(state->buf));
 424         if (tevent_req_nomem(subreq, req)) {
 425                 return tevent_req_post(req, ev);
 426         }
 427         tevent_req_set_callback(subreq, echo_read_done, req);
 428         return req;
 429 }
 430
 431 static int echo_state_destructor(struct echo_state *s)
 432 {
 433         if (s->fd != -1) {
 434                 printf("Closing client fd %d\n", s->fd);
 435                 close(s->fd);
 436                 s->fd = -1;
 437         }
 438         return 0;
 439 }
 440
 441 static void echo_read_done(struct tevent_req *subreq)
 442 {
 443         struct tevent_req *req = tevent_req_callback_data(
 444                 subreq, struct tevent_req);
 445         struct echo_state *state = tevent_req_data(
 446                 req, struct echo_state);
 447         ssize_t nread;
 448         int err;
 449
 450         nread = read_recv(subreq, &err);
 451         TALLOC_FREE(subreq);
 452         if (nread == -1) {
 453                 tevent_req_error(req, err);
 454                 return;
 455         }
 456         if (nread == 0) {
 457                 tevent_req_done(req);
 458                 return;
 459         }
 460
 461         subreq = writeall_send(state, state->ev, state->fd, state->buf, nread);
 462         if (tevent_req_nomem(subreq, req)) {
 463                 return;
 464         }
 465         tevent_req_set_callback(subreq, echo_writeall_done, req);
 466 }
 467
 468 static void echo_writeall_done(struct tevent_req *subreq)
 469 {
 470         struct tevent_req *req = tevent_req_callback_data(
 471                 subreq, struct tevent_req);
 472         struct echo_state *state = tevent_req_data(
 473                 req, struct echo_state);
 474         ssize_t nwritten;
 475         int err;
 476
 477         nwritten = writeall_recv(subreq, &err);
 478         TALLOC_FREE(subreq);
 479         if (nwritten == -1) {
 480                 if (err == EPIPE) {
 481                         tevent_req_done(req);
 482                         return;
 483                 }
 484                 tevent_req_error(req, err);
 485                 return;
 486         }
 487
 488         subreq = read_send(state, state->ev, state->fd,
 489                            state->buf, talloc_get_size(state->buf));
 490         if (tevent_req_nomem(subreq, req)) {
 491                 return;
 492         }
 493         tevent_req_set_callback(subreq, echo_read_done, req);
 494 }
 495
 496 static bool echo_recv(struct tevent_req *req, int *perr)
 497 {
 498         int err;
 499
 500         if (tevent_req_is_unix_error(req, &err)) {
 501                 *perr = err;
 502                 return false;
 503         }
 504         return true;
 505 }
 506
 507 /**
 508  * @brief Full echo handler code accepting and handling clients
 509  */
 510
 511 struct echo_server_state {
 512         struct tevent_context *ev;
 513         int listen_sock;
 514 };
 515
 516 static void echo_server_accepted(struct tevent_req *subreq);
 517 static void echo_server_client_done(struct tevent_req *subreq);
 518
 519 static struct tevent_req *echo_server_send(TALLOC_CTX *mem_ctx,
 520                                            struct tevent_context *ev,
 521                                            int listen_sock)
 522 {
 523         struct tevent_req *req, *subreq;
 524         struct echo_server_state *state;
 525
 526         req = tevent_req_create(mem_ctx, &state,
 527                                 struct echo_server_state);
 528         if (req == NULL) {
 529                 return NULL;
 530         }
 531         state->ev = ev;
 532         state->listen_sock = listen_sock;
 533
 534         subreq = accept_send(state, state->ev, state->listen_sock);
 535         if (tevent_req_nomem(subreq, req)) {
 536                 return tevent_req_post(req, ev);
 537         }
 538         tevent_req_set_callback(subreq, echo_server_accepted, req);
 539         return req;
 540 }
 541
 542 static void echo_server_accepted(struct tevent_req *subreq)
 543 {
 544         struct tevent_req *req = tevent_req_callback_data(
 545                 subreq, struct tevent_req);
 546         struct echo_server_state *state = tevent_req_data(
 547                 req, struct echo_server_state);
 548         int sock, err;
 549
 550         sock = accept_recv(subreq, NULL, NULL, &err);
 551         TALLOC_FREE(subreq);
 552         if (sock == -1) {
 553                 tevent_req_error(req, err);
 554                 return;
 555         }
 556
 557         printf("new client fd %d\n", sock);
 558
 559         subreq = echo_send(state, state->ev, sock, 100);
 560         if (tevent_req_nomem(subreq, req)) {
 561                 return;
 562         }
 563         tevent_req_set_callback(subreq, echo_server_client_done, req);
 564
 565         subreq = accept_send(state, state->ev, state->listen_sock);
 566         if (tevent_req_nomem(subreq, req)) {
 567                 return;
 568         }
 569         tevent_req_set_callback(subreq, echo_server_accepted, req);
 570 }
 571
 572 static void echo_server_client_done(struct tevent_req *subreq)
 573 {
 574         bool ret;
 575         int err;
 576
 577         ret = echo_recv(subreq, &err);
 578         TALLOC_FREE(subreq);
 579
 580         if (ret) {
 581                 printf("Client done\n");
 582         } else {
 583                 printf("Client failed: %s\n", strerror(err));
 584         }
 585 }
 586
 587 static bool echo_server_recv(struct tevent_req *req, int *perr)
 588 {
 589         int err;
 590
 591         if (tevent_req_is_unix_error(req, &err)) {
 592                 *perr = err;
 593                 return false;
 594         }
 595         return true;
 596 }
 597
 598 int main(int argc, const char **argv)
 599 {
 600         int ret, port, listen_sock, err;
 601         struct tevent_context *ev;
 602         struct sockaddr_in addr;
 603         struct tevent_req *req;
 604         bool result;
 605
 606         if (argc != 2) {
 607                 fprintf(stderr, "Usage: %s <port>\n", argv[0]);
 608                 exit(1);
 609         }
 610
 611         port = atoi(argv[1]);
 612
 613         printf("listening on port %d\n", port);
 614
 615         listen_sock = socket(AF_INET, SOCK_STREAM, 0);
 616
 617         if (listen_sock == -1) {
 618                 perror("socket() failed");
 619                 exit(1);
 620         }
 621
 622         addr = (struct sockaddr_in) {
 623                 .sin_family = AF_INET,
 624                 .sin_port = htons(port)
 625         };
 626
 627         ret = bind(listen_sock, (struct sockaddr *)&addr, sizeof(addr));
 628         if (ret == -1) {
 629                 perror("bind() failed");
 630                 exit(1);
 631         }
 632
 633         ret = listen(listen_sock, 5);
 634         if (ret == -1) {
 635                 perror("listen() failed");
 636                 exit(1);
 637         }
 638
 639         ev = tevent_context_init(NULL);
 640         if (ev == NULL) {
 641                 fprintf(stderr, "tevent_context_init failed\n");
 642                 exit(1);
 643         }
 644
 645         req = echo_server_send(ev, ev, listen_sock);
 646         if (req == NULL) {
 647                 fprintf(stderr, "echo_server_send failed\n");
 648                 exit(1);
 649         }
 650
 651         if (!tevent_req_poll(req, ev)) {
 652                 perror("tevent_req_poll() failed");
 653                 exit(1);
 654         }
 655
 656         result = echo_server_recv(req, &err);
 657         TALLOC_FREE(req);
 658         if (!result) {
 659                 fprintf(stderr, "echo_server failed: %s\n", strerror(err));
 660                 exit(1);
 661         }
 662
 663         return 0;
 664 }