sftp-server.c

   1 /* $OpenBSD: sftp-server.c,v 1.92 2010/11/04 02:45:34 djm Exp $ */
   2 /*
   3  * Copyright (c) 2000-2004 Markus Friedl.  All rights reserved.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include "includes.h"
  19
  20 #include <sys/types.h>
  21 #include <sys/param.h>
  22 #include <sys/stat.h>
  23 #ifdef HAVE_SYS_TIME_H
  24 # include <sys/time.h>
  25 #endif
  26 #ifdef HAVE_SYS_MOUNT_H
  27 #include <sys/mount.h>
  28 #endif
  29 #ifdef HAVE_SYS_STATVFS_H
  30 #include <sys/statvfs.h>
  31 #endif
  32
  33 #include <dirent.h>
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <pwd.h>
  37 #include <stdlib.h>
  38 #include <stdio.h>
  39 #include <string.h>
  40 #include <pwd.h>
  41 #include <time.h>
  42 #include <unistd.h>
  43 #include <stdarg.h>
  44
  45 #include "xmalloc.h"
  46 #include "buffer.h"
  47 #include "log.h"
  48 #include "misc.h"
  49 #include "uidswap.h"
  50
  51 #include "sftp.h"
  52 #include "sftp-common.h"
  53
  54 /* helper */
  55 #define get_int64()                     buffer_get_int64(&iqueue);
  56 #define get_int()                       buffer_get_int(&iqueue);
  57 #define get_string(lenp)                buffer_get_string(&iqueue, lenp);
  58
  59 /* Our verbosity */
  60 LogLevel log_level = SYSLOG_LEVEL_ERROR;
  61
  62 /* Our client */
  63 struct passwd *pw = NULL;
  64 char *client_addr = NULL;
  65
  66 /* input and output queue */
  67 Buffer iqueue;
  68 Buffer oqueue;
  69
  70 /* Version of client */
  71 int version;
  72
  73 /* Disable writes */
  74 int readonly;
  75
  76 /* portable attributes, etc. */
  77
  78 typedef struct Stat Stat;
  79
  80 struct Stat {
  81         char *name;
  82         char *long_name;
  83         Attrib attrib;
  84 };
  85
  86 static int
  87 errno_to_portable(int unixerrno)
  88 {
  89         int ret = 0;
  90
  91         switch (unixerrno) {
  92         case 0:
  93                 ret = SSH2_FX_OK;
  94                 break;
  95         case ENOENT:
  96         case ENOTDIR:
  97         case EBADF:
  98         case ELOOP:
  99                 ret = SSH2_FX_NO_SUCH_FILE;
 100                 break;
 101         case EPERM:
 102         case EACCES:
 103         case EFAULT:
 104                 ret = SSH2_FX_PERMISSION_DENIED;
 105                 break;
 106         case ENAMETOOLONG:
 107         case EINVAL:
 108                 ret = SSH2_FX_BAD_MESSAGE;
 109                 break;
 110         case ENOSYS:
 111                 ret = SSH2_FX_OP_UNSUPPORTED;
 112                 break;
 113         default:
 114                 ret = SSH2_FX_FAILURE;
 115                 break;
 116         }
 117         return ret;
 118 }
 119
 120 static int
 121 flags_from_portable(int pflags)
 122 {
 123         int flags = 0;
 124
 125         if ((pflags & SSH2_FXF_READ) &&
 126             (pflags & SSH2_FXF_WRITE)) {
 127                 flags = O_RDWR;
 128         } else if (pflags & SSH2_FXF_READ) {
 129                 flags = O_RDONLY;
 130         } else if (pflags & SSH2_FXF_WRITE) {
 131                 flags = O_WRONLY;
 132         }
 133         if (pflags & SSH2_FXF_CREAT)
 134                 flags |= O_CREAT;
 135         if (pflags & SSH2_FXF_TRUNC)
 136                 flags |= O_TRUNC;
 137         if (pflags & SSH2_FXF_EXCL)
 138                 flags |= O_EXCL;
 139         return flags;
 140 }
 141
 142 static const char *
 143 string_from_portable(int pflags)
 144 {
 145         static char ret[128];
 146
 147         *ret = '\0';
 148
 149 #define PAPPEND(str)    {                               \
 150                 if (*ret != '\0')                       \
 151                         strlcat(ret, ",", sizeof(ret)); \
 152                 strlcat(ret, str, sizeof(ret));         \
 153         }
 154
 155         if (pflags & SSH2_FXF_READ)
 156                 PAPPEND("READ")
 157         if (pflags & SSH2_FXF_WRITE)
 158                 PAPPEND("WRITE")
 159         if (pflags & SSH2_FXF_CREAT)
 160                 PAPPEND("CREATE")
 161         if (pflags & SSH2_FXF_TRUNC)
 162                 PAPPEND("TRUNCATE")
 163         if (pflags & SSH2_FXF_EXCL)
 164                 PAPPEND("EXCL")
 165
 166         return ret;
 167 }
 168
 169 static Attrib *
 170 get_attrib(void)
 171 {
 172         return decode_attrib(&iqueue);
 173 }
 174
 175 /* handle handles */
 176
 177 typedef struct Handle Handle;
 178 struct Handle {
 179         int use;
 180         DIR *dirp;
 181         int fd;
 182         char *name;
 183         u_int64_t bytes_read, bytes_write;
 184         int next_unused;
 185 };
 186
 187 enum {
 188         HANDLE_UNUSED,
 189         HANDLE_DIR,
 190         HANDLE_FILE
 191 };
 192
 193 Handle *handles = NULL;
 194 u_int num_handles = 0;
 195 int first_unused_handle = -1;
 196
 197 static void handle_unused(int i)
 198 {
 199         handles[i].use = HANDLE_UNUSED;
 200         handles[i].next_unused = first_unused_handle;
 201         first_unused_handle = i;
 202 }
 203
 204 static int
 205 handle_new(int use, const char *name, int fd, DIR *dirp)
 206 {
 207         int i;
 208
 209         if (first_unused_handle == -1) {
 210                 if (num_handles + 1 <= num_handles)
 211                         return -1;
 212                 num_handles++;
 213                 handles = xrealloc(handles, num_handles, sizeof(Handle));
 214                 handle_unused(num_handles - 1);
 215         }
 216
 217         i = first_unused_handle;
 218         first_unused_handle = handles[i].next_unused;
 219
 220         handles[i].use = use;
 221         handles[i].dirp = dirp;
 222         handles[i].fd = fd;
 223         handles[i].name = xstrdup(name);
 224         handles[i].bytes_read = handles[i].bytes_write = 0;
 225
 226         return i;
 227 }
 228
 229 static int
 230 handle_is_ok(int i, int type)
 231 {
 232         return i >= 0 && (u_int)i < num_handles && handles[i].use == type;
 233 }
 234
 235 static int
 236 handle_to_string(int handle, char **stringp, int *hlenp)
 237 {
 238         if (stringp == NULL || hlenp == NULL)
 239                 return -1;
 240         *stringp = xmalloc(sizeof(int32_t));
 241         put_u32(*stringp, handle);
 242         *hlenp = sizeof(int32_t);
 243         return 0;
 244 }
 245
 246 static int
 247 handle_from_string(const char *handle, u_int hlen)
 248 {
 249         int val;
 250
 251         if (hlen != sizeof(int32_t))
 252                 return -1;
 253         val = get_u32(handle);
 254         if (handle_is_ok(val, HANDLE_FILE) ||
 255             handle_is_ok(val, HANDLE_DIR))
 256                 return val;
 257         return -1;
 258 }
 259
 260 static char *
 261 handle_to_name(int handle)
 262 {
 263         if (handle_is_ok(handle, HANDLE_DIR)||
 264             handle_is_ok(handle, HANDLE_FILE))
 265                 return handles[handle].name;
 266         return NULL;
 267 }
 268
 269 static DIR *
 270 handle_to_dir(int handle)
 271 {
 272         if (handle_is_ok(handle, HANDLE_DIR))
 273                 return handles[handle].dirp;
 274         return NULL;
 275 }
 276
 277 static int
 278 handle_to_fd(int handle)
 279 {
 280         if (handle_is_ok(handle, HANDLE_FILE))
 281                 return handles[handle].fd;
 282         return -1;
 283 }
 284
 285 static void
 286 handle_update_read(int handle, ssize_t bytes)
 287 {
 288         if (handle_is_ok(handle, HANDLE_FILE) && bytes > 0)
 289                 handles[handle].bytes_read += bytes;
 290 }
 291
 292 static void
 293 handle_update_write(int handle, ssize_t bytes)
 294 {
 295         if (handle_is_ok(handle, HANDLE_FILE) && bytes > 0)
 296                 handles[handle].bytes_write += bytes;
 297 }
 298
 299 static u_int64_t
 300 handle_bytes_read(int handle)
 301 {
 302         if (handle_is_ok(handle, HANDLE_FILE))
 303                 return (handles[handle].bytes_read);
 304         return 0;
 305 }
 306
 307 static u_int64_t
 308 handle_bytes_write(int handle)
 309 {
 310         if (handle_is_ok(handle, HANDLE_FILE))
 311                 return (handles[handle].bytes_write);
 312         return 0;
 313 }
 314
 315 static int
 316 handle_close(int handle)
 317 {
 318         int ret = -1;
 319
 320         if (handle_is_ok(handle, HANDLE_FILE)) {
 321                 ret = close(handles[handle].fd);
 322                 xfree(handles[handle].name);
 323                 handle_unused(handle);
 324         } else if (handle_is_ok(handle, HANDLE_DIR)) {
 325                 ret = closedir(handles[handle].dirp);
 326                 xfree(handles[handle].name);
 327                 handle_unused(handle);
 328         } else {
 329                 errno = ENOENT;
 330         }
 331         return ret;
 332 }
 333
 334 static void
 335 handle_log_close(int handle, char *emsg)
 336 {
 337         if (handle_is_ok(handle, HANDLE_FILE)) {
 338                 logit("%s%sclose \"%s\" bytes read %llu written %llu",
 339                     emsg == NULL ? "" : emsg, emsg == NULL ? "" : " ",
 340                     handle_to_name(handle),
 341                     (unsigned long long)handle_bytes_read(handle),
 342                     (unsigned long long)handle_bytes_write(handle));
 343         } else {
 344                 logit("%s%sclosedir \"%s\"",
 345                     emsg == NULL ? "" : emsg, emsg == NULL ? "" : " ",
 346                     handle_to_name(handle));
 347         }
 348 }
 349
 350 static void
 351 handle_log_exit(void)
 352 {
 353         u_int i;
 354
 355         for (i = 0; i < num_handles; i++)
 356                 if (handles[i].use != HANDLE_UNUSED)
 357                         handle_log_close(i, "forced");
 358 }
 359
 360 static int
 361 get_handle(void)
 362 {
 363         char *handle;
 364         int val = -1;
 365         u_int hlen;
 366
 367         handle = get_string(&hlen);
 368         if (hlen < 256)
 369                 val = handle_from_string(handle, hlen);
 370         xfree(handle);
 371         return val;
 372 }
 373
 374 /* send replies */
 375
 376 static void
 377 send_msg(Buffer *m)
 378 {
 379         int mlen = buffer_len(m);
 380
 381         buffer_put_int(&oqueue, mlen);
 382         buffer_append(&oqueue, buffer_ptr(m), mlen);
 383         buffer_consume(m, mlen);
 384 }
 385
 386 static const char *
 387 status_to_message(u_int32_t status)
 388 {
 389         const char *status_messages[] = {
 390                 "Success",                      /* SSH_FX_OK */
 391                 "End of file",                  /* SSH_FX_EOF */
 392                 "No such file",                 /* SSH_FX_NO_SUCH_FILE */
 393                 "Permission denied",            /* SSH_FX_PERMISSION_DENIED */
 394                 "Failure",                      /* SSH_FX_FAILURE */
 395                 "Bad message",                  /* SSH_FX_BAD_MESSAGE */
 396                 "No connection",                /* SSH_FX_NO_CONNECTION */
 397                 "Connection lost",              /* SSH_FX_CONNECTION_LOST */
 398                 "Operation unsupported",        /* SSH_FX_OP_UNSUPPORTED */
 399                 "Unknown error"                 /* Others */
 400         };
 401         return (status_messages[MIN(status,SSH2_FX_MAX)]);
 402 }
 403
 404 static void
 405 send_status(u_int32_t id, u_int32_t status)
 406 {
 407         Buffer msg;
 408
 409         debug3("request %u: sent status %u", id, status);
 410         if (log_level > SYSLOG_LEVEL_VERBOSE ||
 411             (status != SSH2_FX_OK && status != SSH2_FX_EOF))
 412                 logit("sent status %s", status_to_message(status));
 413         buffer_init(&msg);
 414         buffer_put_char(&msg, SSH2_FXP_STATUS);
 415         buffer_put_int(&msg, id);
 416         buffer_put_int(&msg, status);
 417         if (version >= 3) {
 418                 buffer_put_cstring(&msg, status_to_message(status));
 419                 buffer_put_cstring(&msg, "");
 420         }
 421         send_msg(&msg);
 422         buffer_free(&msg);
 423 }
 424 static void
 425 send_data_or_handle(char type, u_int32_t id, const char *data, int dlen)
 426 {
 427         Buffer msg;
 428
 429         buffer_init(&msg);
 430         buffer_put_char(&msg, type);
 431         buffer_put_int(&msg, id);
 432         buffer_put_string(&msg, data, dlen);
 433         send_msg(&msg);
 434         buffer_free(&msg);
 435 }
 436
 437 static void
 438 send_data(u_int32_t id, const char *data, int dlen)
 439 {
 440         debug("request %u: sent data len %d", id, dlen);
 441         send_data_or_handle(SSH2_FXP_DATA, id, data, dlen);
 442 }
 443
 444 static void
 445 send_handle(u_int32_t id, int handle)
 446 {
 447         char *string;
 448         int hlen;
 449
 450         handle_to_string(handle, &string, &hlen);
 451         debug("request %u: sent handle handle %d", id, handle);
 452         send_data_or_handle(SSH2_FXP_HANDLE, id, string, hlen);
 453         xfree(string);
 454 }
 455
 456 static void
 457 send_names(u_int32_t id, int count, const Stat *stats)
 458 {
 459         Buffer msg;
 460         int i;
 461
 462         buffer_init(&msg);
 463         buffer_put_char(&msg, SSH2_FXP_NAME);
 464         buffer_put_int(&msg, id);
 465         buffer_put_int(&msg, count);
 466         debug("request %u: sent names count %d", id, count);
 467         for (i = 0; i < count; i++) {
 468                 buffer_put_cstring(&msg, stats[i].name);
 469                 buffer_put_cstring(&msg, stats[i].long_name);
 470                 encode_attrib(&msg, &stats[i].attrib);
 471         }
 472         send_msg(&msg);
 473         buffer_free(&msg);
 474 }
 475
 476 static void
 477 send_attrib(u_int32_t id, const Attrib *a)
 478 {
 479         Buffer msg;
 480
 481         debug("request %u: sent attrib have 0x%x", id, a->flags);
 482         buffer_init(&msg);
 483         buffer_put_char(&msg, SSH2_FXP_ATTRS);
 484         buffer_put_int(&msg, id);
 485         encode_attrib(&msg, a);
 486         send_msg(&msg);
 487         buffer_free(&msg);
 488 }
 489
 490 static void
 491 send_statvfs(u_int32_t id, struct statvfs *st)
 492 {
 493         Buffer msg;
 494         u_int64_t flag;
 495
 496         flag = (st->f_flag & ST_RDONLY) ? SSH2_FXE_STATVFS_ST_RDONLY : 0;
 497         flag |= (st->f_flag & ST_NOSUID) ? SSH2_FXE_STATVFS_ST_NOSUID : 0;
 498
 499         buffer_init(&msg);
 500         buffer_put_char(&msg, SSH2_FXP_EXTENDED_REPLY);
 501         buffer_put_int(&msg, id);
 502         buffer_put_int64(&msg, st->f_bsize);
 503         buffer_put_int64(&msg, st->f_frsize);
 504         buffer_put_int64(&msg, st->f_blocks);
 505         buffer_put_int64(&msg, st->f_bfree);
 506         buffer_put_int64(&msg, st->f_bavail);
 507         buffer_put_int64(&msg, st->f_files);
 508         buffer_put_int64(&msg, st->f_ffree);
 509         buffer_put_int64(&msg, st->f_favail);
 510         buffer_put_int64(&msg, FSID_TO_ULONG(st->f_fsid));
 511         buffer_put_int64(&msg, flag);
 512         buffer_put_int64(&msg, st->f_namemax);
 513         send_msg(&msg);
 514         buffer_free(&msg);
 515 }
 516
 517 /* parse incoming */
 518
 519 static void
 520 process_init(void)
 521 {
 522         Buffer msg;
 523
 524         version = get_int();
 525         verbose("received client version %d", version);
 526         buffer_init(&msg);
 527         buffer_put_char(&msg, SSH2_FXP_VERSION);
 528         buffer_put_int(&msg, SSH2_FILEXFER_VERSION);
 529         /* POSIX rename extension */
 530         buffer_put_cstring(&msg, "posix-rename@openssh.com");
 531         buffer_put_cstring(&msg, "1"); /* version */
 532         /* statvfs extension */
 533         buffer_put_cstring(&msg, "statvfs@openssh.com");
 534         buffer_put_cstring(&msg, "2"); /* version */
 535         /* fstatvfs extension */
 536         buffer_put_cstring(&msg, "fstatvfs@openssh.com");
 537         buffer_put_cstring(&msg, "2"); /* version */
 538         send_msg(&msg);
 539         buffer_free(&msg);
 540 }
 541
 542 static void
 543 process_open(void)
 544 {
 545         u_int32_t id, pflags;
 546         Attrib *a;
 547         char *name;
 548         int handle, fd, flags, mode, status = SSH2_FX_FAILURE;
 549
 550         id = get_int();
 551         name = get_string(NULL);
 552         pflags = get_int();             /* portable flags */
 553         debug3("request %u: open flags %d", id, pflags);
 554         a = get_attrib();
 555         flags = flags_from_portable(pflags);
 556         mode = (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ? a->perm : 0666;
 557         logit("open \"%s\" flags %s mode 0%o",
 558             name, string_from_portable(pflags), mode);
 559         if (readonly &&
 560             ((flags & O_ACCMODE) == O_WRONLY || (flags & O_ACCMODE) == O_RDWR))
 561                 status = SSH2_FX_PERMISSION_DENIED;
 562         else {
 563                 fd = open(name, flags, mode);
 564                 if (fd < 0) {
 565                         status = errno_to_portable(errno);
 566                 } else {
 567                         handle = handle_new(HANDLE_FILE, name, fd, NULL);
 568                         if (handle < 0) {
 569                                 close(fd);
 570                         } else {
 571                                 send_handle(id, handle);
 572                                 status = SSH2_FX_OK;
 573                         }
 574                 }
 575         }
 576         if (status != SSH2_FX_OK)
 577                 send_status(id, status);
 578         xfree(name);
 579 }
 580
 581 static void
 582 process_close(void)
 583 {
 584         u_int32_t id;
 585         int handle, ret, status = SSH2_FX_FAILURE;
 586
 587         id = get_int();
 588         handle = get_handle();
 589         debug3("request %u: close handle %u", id, handle);
 590         handle_log_close(handle, NULL);
 591         ret = handle_close(handle);
 592         status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
 593         send_status(id, status);
 594 }
 595
 596 static void
 597 process_read(void)
 598 {
 599         char buf[64*1024];
 600         u_int32_t id, len;
 601         int handle, fd, ret, status = SSH2_FX_FAILURE;
 602         u_int64_t off;
 603
 604         id = get_int();
 605         handle = get_handle();
 606         off = get_int64();
 607         len = get_int();
 608
 609         debug("request %u: read \"%s\" (handle %d) off %llu len %d",
 610             id, handle_to_name(handle), handle, (unsigned long long)off, len);
 611         if (len > sizeof buf) {
 612                 len = sizeof buf;
 613                 debug2("read change len %d", len);
 614         }
 615         fd = handle_to_fd(handle);
 616         if (fd >= 0) {
 617                 if (lseek(fd, off, SEEK_SET) < 0) {
 618                         error("process_read: seek failed");
 619                         status = errno_to_portable(errno);
 620                 } else {
 621                         ret = read(fd, buf, len);
 622                         if (ret < 0) {
 623                                 status = errno_to_portable(errno);
 624                         } else if (ret == 0) {
 625                                 status = SSH2_FX_EOF;
 626                         } else {
 627                                 send_data(id, buf, ret);
 628                                 status = SSH2_FX_OK;
 629                                 handle_update_read(handle, ret);
 630                         }
 631                 }
 632         }
 633         if (status != SSH2_FX_OK)
 634                 send_status(id, status);
 635 }
 636
 637 static void
 638 process_write(void)
 639 {
 640         u_int32_t id;
 641         u_int64_t off;
 642         u_int len;
 643         int handle, fd, ret, status;
 644         char *data;
 645
 646         id = get_int();
 647         handle = get_handle();
 648         off = get_int64();
 649         data = get_string(&len);
 650
 651         debug("request %u: write \"%s\" (handle %d) off %llu len %d",
 652             id, handle_to_name(handle), handle, (unsigned long long)off, len);
 653         fd = handle_to_fd(handle);
 654
 655         if (fd < 0)
 656                 status = SSH2_FX_FAILURE;
 657         else if (readonly)
 658                 status = SSH2_FX_PERMISSION_DENIED;
 659         else {
 660                 if (lseek(fd, off, SEEK_SET) < 0) {
 661                         status = errno_to_portable(errno);
 662                         error("process_write: seek failed");
 663                 } else {
 664 /* XXX ATOMICIO ? */
 665                         ret = write(fd, data, len);
 666                         if (ret < 0) {
 667                                 error("process_write: write failed");
 668                                 status = errno_to_portable(errno);
 669                         } else if ((size_t)ret == len) {
 670                                 status = SSH2_FX_OK;
 671                                 handle_update_write(handle, ret);
 672                         } else {
 673                                 debug2("nothing at all written");
 674                                 status = SSH2_FX_FAILURE;
 675                         }
 676                 }
 677         }
 678         send_status(id, status);
 679         xfree(data);
 680 }
 681
 682 static void
 683 process_do_stat(int do_lstat)
 684 {
 685         Attrib a;
 686         struct stat st;
 687         u_int32_t id;
 688         char *name;
 689         int ret, status = SSH2_FX_FAILURE;
 690
 691         id = get_int();
 692         name = get_string(NULL);
 693         debug3("request %u: %sstat", id, do_lstat ? "l" : "");
 694         verbose("%sstat name \"%s\"", do_lstat ? "l" : "", name);
 695         ret = do_lstat ? lstat(name, &st) : stat(name, &st);
 696         if (ret < 0) {
 697                 status = errno_to_portable(errno);
 698         } else {
 699                 stat_to_attrib(&st, &a);
 700                 send_attrib(id, &a);
 701                 status = SSH2_FX_OK;
 702         }
 703         if (status != SSH2_FX_OK)
 704                 send_status(id, status);
 705         xfree(name);
 706 }
 707
 708 static void
 709 process_stat(void)
 710 {
 711         process_do_stat(0);
 712 }
 713
 714 static void
 715 process_lstat(void)
 716 {
 717         process_do_stat(1);
 718 }
 719
 720 static void
 721 process_fstat(void)
 722 {
 723         Attrib a;
 724         struct stat st;
 725         u_int32_t id;
 726         int fd, ret, handle, status = SSH2_FX_FAILURE;
 727
 728         id = get_int();
 729         handle = get_handle();
 730         debug("request %u: fstat \"%s\" (handle %u)",
 731             id, handle_to_name(handle), handle);
 732         fd = handle_to_fd(handle);
 733         if (fd >= 0) {
 734                 ret = fstat(fd, &st);
 735                 if (ret < 0) {
 736                         status = errno_to_portable(errno);
 737                 } else {
 738                         stat_to_attrib(&st, &a);
 739                         send_attrib(id, &a);
 740                         status = SSH2_FX_OK;
 741                 }
 742         }
 743         if (status != SSH2_FX_OK)
 744                 send_status(id, status);
 745 }
 746
 747 static struct timeval *
 748 attrib_to_tv(const Attrib *a)
 749 {
 750         static struct timeval tv[2];
 751
 752         tv[0].tv_sec = a->atime;
 753         tv[0].tv_usec = 0;
 754         tv[1].tv_sec = a->mtime;
 755         tv[1].tv_usec = 0;
 756         return tv;
 757 }
 758
 759 static void
 760 process_setstat(void)
 761 {
 762         Attrib *a;
 763         u_int32_t id;
 764         char *name;
 765         int status = SSH2_FX_OK, ret;
 766
 767         id = get_int();
 768         name = get_string(NULL);
 769         a = get_attrib();
 770         debug("request %u: setstat name \"%s\"", id, name);
 771         if (readonly) {
 772                 status = SSH2_FX_PERMISSION_DENIED;
 773                 a->flags = 0;
 774         }
 775         if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
 776                 logit("set \"%s\" size %llu",
 777                     name, (unsigned long long)a->size);
 778                 ret = truncate(name, a->size);
 779                 if (ret == -1)
 780                         status = errno_to_portable(errno);
 781         }
 782         if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
 783                 logit("set \"%s\" mode %04o", name, a->perm);
 784                 ret = chmod(name, a->perm & 07777);
 785                 if (ret == -1)
 786                         status = errno_to_portable(errno);
 787         }
 788         if (a->flags & SSH2_FILEXFER_ATTR_ACMODTIME) {
 789                 char buf[64];
 790                 time_t t = a->mtime;
 791
 792                 strftime(buf, sizeof(buf), "%Y%m%d-%H:%M:%S",
 793                     localtime(&t));
 794                 logit("set \"%s\" modtime %s", name, buf);
 795                 ret = utimes(name, attrib_to_tv(a));
 796                 if (ret == -1)
 797                         status = errno_to_portable(errno);
 798         }
 799         if (a->flags & SSH2_FILEXFER_ATTR_UIDGID) {
 800                 logit("set \"%s\" owner %lu group %lu", name,
 801                     (u_long)a->uid, (u_long)a->gid);
 802                 ret = chown(name, a->uid, a->gid);
 803                 if (ret == -1)
 804                         status = errno_to_portable(errno);
 805         }
 806         send_status(id, status);
 807         xfree(name);
 808 }
 809
 810 static void
 811 process_fsetstat(void)
 812 {
 813         Attrib *a;
 814         u_int32_t id;
 815         int handle, fd, ret;
 816         int status = SSH2_FX_OK;
 817
 818         id = get_int();
 819         handle = get_handle();
 820         a = get_attrib();
 821         debug("request %u: fsetstat handle %d", id, handle);
 822         fd = handle_to_fd(handle);
 823         if (fd < 0)
 824                 status = SSH2_FX_FAILURE;
 825         else if (readonly)
 826                 status = SSH2_FX_PERMISSION_DENIED;
 827         else {
 828                 char *name = handle_to_name(handle);
 829
 830                 if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
 831                         logit("set \"%s\" size %llu",
 832                             name, (unsigned long long)a->size);
 833                         ret = ftruncate(fd, a->size);
 834                         if (ret == -1)
 835                                 status = errno_to_portable(errno);
 836                 }
 837                 if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
 838                         logit("set \"%s\" mode %04o", name, a->perm);
 839 #ifdef HAVE_FCHMOD
 840                         ret = fchmod(fd, a->perm & 07777);
 841 #else
 842                         ret = chmod(name, a->perm & 07777);
 843 #endif
 844                         if (ret == -1)
 845                                 status = errno_to_portable(errno);
 846                 }
 847                 if (a->flags & SSH2_FILEXFER_ATTR_ACMODTIME) {
 848                         char buf[64];
 849                         time_t t = a->mtime;
 850
 851                         strftime(buf, sizeof(buf), "%Y%m%d-%H:%M:%S",
 852                             localtime(&t));
 853                         logit("set \"%s\" modtime %s", name, buf);
 854 #ifdef HAVE_FUTIMES
 855                         ret = futimes(fd, attrib_to_tv(a));
 856 #else
 857                         ret = utimes(name, attrib_to_tv(a));
 858 #endif
 859                         if (ret == -1)
 860                                 status = errno_to_portable(errno);
 861                 }
 862                 if (a->flags & SSH2_FILEXFER_ATTR_UIDGID) {
 863                         logit("set \"%s\" owner %lu group %lu", name,
 864                             (u_long)a->uid, (u_long)a->gid);
 865 #ifdef HAVE_FCHOWN
 866                         ret = fchown(fd, a->uid, a->gid);
 867 #else
 868                         ret = chown(name, a->uid, a->gid);
 869 #endif
 870                         if (ret == -1)
 871                                 status = errno_to_portable(errno);
 872                 }
 873         }
 874         send_status(id, status);
 875 }
 876
 877 static void
 878 process_opendir(void)
 879 {
 880         DIR *dirp = NULL;
 881         char *path;
 882         int handle, status = SSH2_FX_FAILURE;
 883         u_int32_t id;
 884
 885         id = get_int();
 886         path = get_string(NULL);
 887         debug3("request %u: opendir", id);
 888         logit("opendir \"%s\"", path);
 889         dirp = opendir(path);
 890         if (dirp == NULL) {
 891                 status = errno_to_portable(errno);
 892         } else {
 893                 handle = handle_new(HANDLE_DIR, path, 0, dirp);
 894                 if (handle < 0) {
 895                         closedir(dirp);
 896                 } else {
 897                         send_handle(id, handle);
 898                         status = SSH2_FX_OK;
 899                 }
 900
 901         }
 902         if (status != SSH2_FX_OK)
 903                 send_status(id, status);
 904         xfree(path);
 905 }
 906
 907 static void
 908 process_readdir(void)
 909 {
 910         DIR *dirp;
 911         struct dirent *dp;
 912         char *path;
 913         int handle;
 914         u_int32_t id;
 915
 916         id = get_int();
 917         handle = get_handle();
 918         debug("request %u: readdir \"%s\" (handle %d)", id,
 919             handle_to_name(handle), handle);
 920         dirp = handle_to_dir(handle);
 921         path = handle_to_name(handle);
 922         if (dirp == NULL || path == NULL) {
 923                 send_status(id, SSH2_FX_FAILURE);
 924         } else {
 925                 struct stat st;
 926                 char pathname[MAXPATHLEN];
 927                 Stat *stats;
 928                 int nstats = 10, count = 0, i;
 929
 930                 stats = xcalloc(nstats, sizeof(Stat));
 931                 while ((dp = readdir(dirp)) != NULL) {
 932                         if (count >= nstats) {
 933                                 nstats *= 2;
 934                                 stats = xrealloc(stats, nstats, sizeof(Stat));
 935                         }
 936 /* XXX OVERFLOW ? */
 937                         snprintf(pathname, sizeof pathname, "%s%s%s", path,
 938                             strcmp(path, "/") ? "/" : "", dp->d_name);
 939                         if (lstat(pathname, &st) < 0)
 940                                 continue;
 941                         stat_to_attrib(&st, &(stats[count].attrib));
 942                         stats[count].name = xstrdup(dp->d_name);
 943                         stats[count].long_name = ls_file(dp->d_name, &st, 0, 0);
 944                         count++;
 945                         /* send up to 100 entries in one message */
 946                         /* XXX check packet size instead */
 947                         if (count == 100)
 948                                 break;
 949                 }
 950                 if (count > 0) {
 951                         send_names(id, count, stats);
 952                         for (i = 0; i < count; i++) {
 953                                 xfree(stats[i].name);
 954                                 xfree(stats[i].long_name);
 955                         }
 956                 } else {
 957                         send_status(id, SSH2_FX_EOF);
 958                 }
 959                 xfree(stats);
 960         }
 961 }
 962
 963 static void
 964 process_remove(void)
 965 {
 966         char *name;
 967         u_int32_t id;
 968         int status = SSH2_FX_FAILURE;
 969         int ret;
 970
 971         id = get_int();
 972         name = get_string(NULL);
 973         debug3("request %u: remove", id);
 974         logit("remove name \"%s\"", name);
 975         if (readonly)
 976                 status = SSH2_FX_PERMISSION_DENIED;
 977         else {
 978                 ret = unlink(name);
 979                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
 980         }
 981         send_status(id, status);
 982         xfree(name);
 983 }
 984
 985 static void
 986 process_mkdir(void)
 987 {
 988         Attrib *a;
 989         u_int32_t id;
 990         char *name;
 991         int ret, mode, status = SSH2_FX_FAILURE;
 992
 993         id = get_int();
 994         name = get_string(NULL);
 995         a = get_attrib();
 996         mode = (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ?
 997             a->perm & 07777 : 0777;
 998         debug3("request %u: mkdir", id);
 999         logit("mkdir name \"%s\" mode 0%o", name, mode);
1000         if (readonly)
1001                 status = SSH2_FX_PERMISSION_DENIED;
1002         else {
1003                 ret = mkdir(name, mode);
1004                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1005         }
1006         send_status(id, status);
1007         xfree(name);
1008 }
1009
1010 static void
1011 process_rmdir(void)
1012 {
1013         u_int32_t id;
1014         char *name;
1015         int ret, status;
1016
1017         id = get_int();
1018         name = get_string(NULL);
1019         debug3("request %u: rmdir", id);
1020         logit("rmdir name \"%s\"", name);
1021         if (readonly)
1022                 status = SSH2_FX_PERMISSION_DENIED;
1023         else {
1024                 ret = rmdir(name);
1025                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1026         }
1027         send_status(id, status);
1028         xfree(name);
1029 }
1030
1031 static void
1032 process_realpath(void)
1033 {
1034         char resolvedname[MAXPATHLEN];
1035         u_int32_t id;
1036         char *path;
1037
1038         id = get_int();
1039         path = get_string(NULL);
1040         if (path[0] == '\0') {
1041                 xfree(path);
1042                 path = xstrdup(".");
1043         }
1044         debug3("request %u: realpath", id);
1045         verbose("realpath \"%s\"", path);
1046         if (realpath(path, resolvedname) == NULL) {
1047                 send_status(id, errno_to_portable(errno));
1048         } else {
1049                 Stat s;
1050                 attrib_clear(&s.attrib);
1051                 s.name = s.long_name = resolvedname;
1052                 send_names(id, 1, &s);
1053         }
1054         xfree(path);
1055 }
1056
1057 static void
1058 process_rename(void)
1059 {
1060         u_int32_t id;
1061         char *oldpath, *newpath;
1062         int status;
1063         struct stat sb;
1064
1065         id = get_int();
1066         oldpath = get_string(NULL);
1067         newpath = get_string(NULL);
1068         debug3("request %u: rename", id);
1069         logit("rename old \"%s\" new \"%s\"", oldpath, newpath);
1070         status = SSH2_FX_FAILURE;
1071         if (readonly)
1072                 status = SSH2_FX_PERMISSION_DENIED;
1073         else if (lstat(oldpath, &sb) == -1)
1074                 status = errno_to_portable(errno);
1075         else if (S_ISREG(sb.st_mode)) {
1076                 /* Race-free rename of regular files */
1077                 if (link(oldpath, newpath) == -1) {
1078                         if (errno == EOPNOTSUPP || errno == ENOSYS
1079 #ifdef EXDEV
1080                             || errno == EXDEV
1081 #endif
1082 #ifdef LINK_OPNOTSUPP_ERRNO
1083                             || errno == LINK_OPNOTSUPP_ERRNO
1084 #endif
1085                             ) {
1086                                 struct stat st;
1087
1088                                 /*
1089                                  * fs doesn't support links, so fall back to
1090                                  * stat+rename.  This is racy.
1091                                  */
1092                                 if (stat(newpath, &st) == -1) {
1093                                         if (rename(oldpath, newpath) == -1)
1094                                                 status =
1095                                                     errno_to_portable(errno);
1096                                         else
1097                                                 status = SSH2_FX_OK;
1098                                 }
1099                         } else {
1100                                 status = errno_to_portable(errno);
1101                         }
1102                 } else if (unlink(oldpath) == -1) {
1103                         status = errno_to_portable(errno);
1104                         /* clean spare link */
1105                         unlink(newpath);
1106                 } else
1107                         status = SSH2_FX_OK;
1108         } else if (stat(newpath, &sb) == -1) {
1109                 if (rename(oldpath, newpath) == -1)
1110                         status = errno_to_portable(errno);
1111                 else
1112                         status = SSH2_FX_OK;
1113         }
1114         send_status(id, status);
1115         xfree(oldpath);
1116         xfree(newpath);
1117 }
1118
1119 static void
1120 process_readlink(void)
1121 {
1122         u_int32_t id;
1123         int len;
1124         char buf[MAXPATHLEN];
1125         char *path;
1126
1127         id = get_int();
1128         path = get_string(NULL);
1129         debug3("request %u: readlink", id);
1130         verbose("readlink \"%s\"", path);
1131         if ((len = readlink(path, buf, sizeof(buf) - 1)) == -1)
1132                 send_status(id, errno_to_portable(errno));
1133         else {
1134                 Stat s;
1135
1136                 buf[len] = '\0';
1137                 attrib_clear(&s.attrib);
1138                 s.name = s.long_name = buf;
1139                 send_names(id, 1, &s);
1140         }
1141         xfree(path);
1142 }
1143
1144 static void
1145 process_symlink(void)
1146 {
1147         u_int32_t id;
1148         char *oldpath, *newpath;
1149         int ret, status;
1150
1151         id = get_int();
1152         oldpath = get_string(NULL);
1153         newpath = get_string(NULL);
1154         debug3("request %u: symlink", id);
1155         logit("symlink old \"%s\" new \"%s\"", oldpath, newpath);
1156         /* this will fail if 'newpath' exists */
1157         if (readonly)
1158                 status = SSH2_FX_PERMISSION_DENIED;
1159         else {
1160                 ret = symlink(oldpath, newpath);
1161                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1162         }
1163         send_status(id, status);
1164         xfree(oldpath);
1165         xfree(newpath);
1166 }
1167
1168 static void
1169 process_extended_posix_rename(u_int32_t id)
1170 {
1171         char *oldpath, *newpath;
1172         int ret, status;
1173
1174         oldpath = get_string(NULL);
1175         newpath = get_string(NULL);
1176         debug3("request %u: posix-rename", id);
1177         logit("posix-rename old \"%s\" new \"%s\"", oldpath, newpath);
1178         if (readonly)
1179                 status = SSH2_FX_PERMISSION_DENIED;
1180         else {
1181                 ret = rename(oldpath, newpath);
1182                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1183         }
1184         send_status(id, status);
1185         xfree(oldpath);
1186         xfree(newpath);
1187 }
1188
1189 static void
1190 process_extended_statvfs(u_int32_t id)
1191 {
1192         char *path;
1193         struct statvfs st;
1194
1195         path = get_string(NULL);
1196         debug3("request %u: statfs", id);
1197         logit("statfs \"%s\"", path);
1198
1199         if (statvfs(path, &st) != 0)
1200                 send_status(id, errno_to_portable(errno));
1201         else
1202                 send_statvfs(id, &st);
1203         xfree(path);
1204 }
1205
1206 static void
1207 process_extended_fstatvfs(u_int32_t id)
1208 {
1209         int handle, fd;
1210         struct statvfs st;
1211
1212         handle = get_handle();
1213         debug("request %u: fstatvfs \"%s\" (handle %u)",
1214             id, handle_to_name(handle), handle);
1215         if ((fd = handle_to_fd(handle)) < 0) {
1216                 send_status(id, SSH2_FX_FAILURE);
1217                 return;
1218         }
1219         if (fstatvfs(fd, &st) != 0)
1220                 send_status(id, errno_to_portable(errno));
1221         else
1222                 send_statvfs(id, &st);
1223 }
1224
1225 static void
1226 process_extended(void)
1227 {
1228         u_int32_t id;
1229         char *request;
1230
1231         id = get_int();
1232         request = get_string(NULL);
1233         if (strcmp(request, "posix-rename@openssh.com") == 0)
1234                 process_extended_posix_rename(id);
1235         else if (strcmp(request, "statvfs@openssh.com") == 0)
1236                 process_extended_statvfs(id);
1237         else if (strcmp(request, "fstatvfs@openssh.com") == 0)
1238                 process_extended_fstatvfs(id);
1239         else
1240                 send_status(id, SSH2_FX_OP_UNSUPPORTED);        /* MUST */
1241         xfree(request);
1242 }
1243
1244 /* stolen from ssh-agent */
1245
1246 static void
1247 process(void)
1248 {
1249         u_int msg_len;
1250         u_int buf_len;
1251         u_int consumed;
1252         u_int type;
1253         u_char *cp;
1254
1255         buf_len = buffer_len(&iqueue);
1256         if (buf_len < 5)
1257                 return;         /* Incomplete message. */
1258         cp = buffer_ptr(&iqueue);
1259         msg_len = get_u32(cp);
1260         if (msg_len > SFTP_MAX_MSG_LENGTH) {
1261                 error("bad message from %s local user %s",
1262                     client_addr, pw->pw_name);
1263                 sftp_server_cleanup_exit(11);
1264         }
1265         if (buf_len < msg_len + 4)
1266                 return;
1267         buffer_consume(&iqueue, 4);
1268         buf_len -= 4;
1269         type = buffer_get_char(&iqueue);
1270         switch (type) {
1271         case SSH2_FXP_INIT:
1272                 process_init();
1273                 break;
1274         case SSH2_FXP_OPEN:
1275                 process_open();
1276                 break;
1277         case SSH2_FXP_CLOSE:
1278                 process_close();
1279                 break;
1280         case SSH2_FXP_READ:
1281                 process_read();
1282                 break;
1283         case SSH2_FXP_WRITE:
1284                 process_write();
1285                 break;
1286         case SSH2_FXP_LSTAT:
1287                 process_lstat();
1288                 break;
1289         case SSH2_FXP_FSTAT:
1290                 process_fstat();
1291                 break;
1292         case SSH2_FXP_SETSTAT:
1293                 process_setstat();
1294                 break;
1295         case SSH2_FXP_FSETSTAT:
1296                 process_fsetstat();
1297                 break;
1298         case SSH2_FXP_OPENDIR:
1299                 process_opendir();
1300                 break;
1301         case SSH2_FXP_READDIR:
1302                 process_readdir();
1303                 break;
1304         case SSH2_FXP_REMOVE:
1305                 process_remove();
1306                 break;
1307         case SSH2_FXP_MKDIR:
1308                 process_mkdir();
1309                 break;
1310         case SSH2_FXP_RMDIR:
1311                 process_rmdir();
1312                 break;
1313         case SSH2_FXP_REALPATH:
1314                 process_realpath();
1315                 break;
1316         case SSH2_FXP_STAT:
1317                 process_stat();
1318                 break;
1319         case SSH2_FXP_RENAME:
1320                 process_rename();
1321                 break;
1322         case SSH2_FXP_READLINK:
1323                 process_readlink();
1324                 break;
1325         case SSH2_FXP_SYMLINK:
1326                 process_symlink();
1327                 break;
1328         case SSH2_FXP_EXTENDED:
1329                 process_extended();
1330                 break;
1331         default:
1332                 error("Unknown message %d", type);
1333                 break;
1334         }
1335         /* discard the remaining bytes from the current packet */
1336         if (buf_len < buffer_len(&iqueue)) {
1337                 error("iqueue grew unexpectedly");
1338                 sftp_server_cleanup_exit(255);
1339         }
1340         consumed = buf_len - buffer_len(&iqueue);
1341         if (msg_len < consumed) {
1342                 error("msg_len %d < consumed %d", msg_len, consumed);
1343                 sftp_server_cleanup_exit(255);
1344         }
1345         if (msg_len > consumed)
1346                 buffer_consume(&iqueue, msg_len - consumed);
1347 }
1348
1349 /* Cleanup handler that logs active handles upon normal exit */
1350 void
1351 sftp_server_cleanup_exit(int i)
1352 {
1353         if (pw != NULL && client_addr != NULL) {
1354                 handle_log_exit();
1355                 logit("session closed for local user %s from [%s]",
1356                     pw->pw_name, client_addr);
1357         }
1358         _exit(i);
1359 }
1360
1361 static void
1362 sftp_server_usage(void)
1363 {
1364         extern char *__progname;
1365
1366         fprintf(stderr,
1367             "usage: %s [-ehR] [-f log_facility] [-l log_level] [-u umask]\n",
1368             __progname);
1369         exit(1);
1370 }
1371
1372 int
1373 sftp_server_main(int argc, char **argv, struct passwd *user_pw)
1374 {
1375         fd_set *rset, *wset;
1376         int in, out, max, ch, skipargs = 0, log_stderr = 0;
1377         ssize_t len, olen, set_size;
1378         SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
1379         char *cp, buf[4*4096];
1380         long mask;
1381
1382         extern char *optarg;
1383         extern char *__progname;
1384
1385         __progname = ssh_get_progname(argv[0]);
1386         log_init(__progname, log_level, log_facility, log_stderr);
1387
1388         while (!skipargs && (ch = getopt(argc, argv, "f:l:u:cehR")) != -1) {
1389                 switch (ch) {
1390                 case 'R':
1391                         readonly = 1;
1392                         break;
1393                 case 'c':
1394                         /*
1395                          * Ignore all arguments if we are invoked as a
1396                          * shell using "sftp-server -c command"
1397                          */
1398                         skipargs = 1;
1399                         break;
1400                 case 'e':
1401                         log_stderr = 1;
1402                         break;
1403                 case 'l':
1404                         log_level = log_level_number(optarg);
1405                         if (log_level == SYSLOG_LEVEL_NOT_SET)
1406                                 error("Invalid log level \"%s\"", optarg);
1407                         break;
1408                 case 'f':
1409                         log_facility = log_facility_number(optarg);
1410                         if (log_facility == SYSLOG_FACILITY_NOT_SET)
1411                                 error("Invalid log facility \"%s\"", optarg);
1412                         break;
1413                 case 'u':
1414                         errno = 0;
1415                         mask = strtol(optarg, &cp, 8);
1416                         if (mask < 0 || mask > 0777 || *cp != '\0' ||
1417                             cp == optarg || (mask == 0 && errno != 0))
1418                                 fatal("Invalid umask \"%s\"", optarg);
1419                         (void)umask((mode_t)mask);
1420                         break;
1421                 case 'h':
1422                 default:
1423                         sftp_server_usage();
1424                 }
1425         }
1426
1427         log_init(__progname, log_level, log_facility, log_stderr);
1428
1429         if ((cp = getenv("SSH_CONNECTION")) != NULL) {
1430                 client_addr = xstrdup(cp);
1431                 if ((cp = strchr(client_addr, ' ')) == NULL) {
1432                         error("Malformed SSH_CONNECTION variable: \"%s\"",
1433                             getenv("SSH_CONNECTION"));
1434                         sftp_server_cleanup_exit(255);
1435                 }
1436                 *cp = '\0';
1437         } else
1438                 client_addr = xstrdup("UNKNOWN");
1439
1440         pw = pwcopy(user_pw);
1441
1442         logit("session opened for local user %s from [%s]",
1443             pw->pw_name, client_addr);
1444
1445         in = STDIN_FILENO;
1446         out = STDOUT_FILENO;
1447
1448 #ifdef HAVE_CYGWIN
1449         setmode(in, O_BINARY);
1450         setmode(out, O_BINARY);
1451 #endif
1452
1453         max = 0;
1454         if (in > max)
1455                 max = in;
1456         if (out > max)
1457                 max = out;
1458
1459         buffer_init(&iqueue);
1460         buffer_init(&oqueue);
1461
1462         set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
1463         rset = (fd_set *)xmalloc(set_size);
1464         wset = (fd_set *)xmalloc(set_size);
1465
1466         for (;;) {
1467                 memset(rset, 0, set_size);
1468                 memset(wset, 0, set_size);
1469
1470                 /*
1471                  * Ensure that we can read a full buffer and handle
1472                  * the worst-case length packet it can generate,
1473                  * otherwise apply backpressure by stopping reads.
1474                  */
1475                 if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
1476                     buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
1477                         FD_SET(in, rset);
1478
1479                 olen = buffer_len(&oqueue);
1480                 if (olen > 0)
1481                         FD_SET(out, wset);
1482
1483                 if (select(max+1, rset, wset, NULL, NULL) < 0) {
1484                         if (errno == EINTR)
1485                                 continue;
1486                         error("select: %s", strerror(errno));
1487                         sftp_server_cleanup_exit(2);
1488                 }
1489
1490                 /* copy stdin to iqueue */
1491                 if (FD_ISSET(in, rset)) {
1492                         len = read(in, buf, sizeof buf);
1493                         if (len == 0) {
1494                                 debug("read eof");
1495                                 sftp_server_cleanup_exit(0);
1496                         } else if (len < 0) {
1497                                 error("read: %s", strerror(errno));
1498                                 sftp_server_cleanup_exit(1);
1499                         } else {
1500                                 buffer_append(&iqueue, buf, len);
1501                         }
1502                 }
1503                 /* send oqueue to stdout */
1504                 if (FD_ISSET(out, wset)) {
1505                         len = write(out, buffer_ptr(&oqueue), olen);
1506                         if (len < 0) {
1507                                 error("write: %s", strerror(errno));
1508                                 sftp_server_cleanup_exit(1);
1509                         } else {
1510                                 buffer_consume(&oqueue, len);
1511                         }
1512                 }
1513
1514                 /*
1515                  * Process requests from client if we can fit the results
1516                  * into the output buffer, otherwise stop processing input
1517                  * and let the output queue drain.
1518                  */
1519                 if (buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
1520                         process();
1521         }
1522 }