sftp-server.c

   1 /* $OpenBSD: sftp-server.c,v 1.93 2010/12/04 00:18:01 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         /* hardlink extension */
 539         buffer_put_cstring(&msg, "hardlink@openssh.com");
 540         buffer_put_cstring(&msg, "1"); /* version */
 541         send_msg(&msg);
 542         buffer_free(&msg);
 543 }
 544
 545 static void
 546 process_open(void)
 547 {
 548         u_int32_t id, pflags;
 549         Attrib *a;
 550         char *name;
 551         int handle, fd, flags, mode, status = SSH2_FX_FAILURE;
 552
 553         id = get_int();
 554         name = get_string(NULL);
 555         pflags = get_int();             /* portable flags */
 556         debug3("request %u: open flags %d", id, pflags);
 557         a = get_attrib();
 558         flags = flags_from_portable(pflags);
 559         mode = (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ? a->perm : 0666;
 560         logit("open \"%s\" flags %s mode 0%o",
 561             name, string_from_portable(pflags), mode);
 562         if (readonly &&
 563             ((flags & O_ACCMODE) == O_WRONLY || (flags & O_ACCMODE) == O_RDWR))
 564                 status = SSH2_FX_PERMISSION_DENIED;
 565         else {
 566                 fd = open(name, flags, mode);
 567                 if (fd < 0) {
 568                         status = errno_to_portable(errno);
 569                 } else {
 570                         handle = handle_new(HANDLE_FILE, name, fd, NULL);
 571                         if (handle < 0) {
 572                                 close(fd);
 573                         } else {
 574                                 send_handle(id, handle);
 575                                 status = SSH2_FX_OK;
 576                         }
 577                 }
 578         }
 579         if (status != SSH2_FX_OK)
 580                 send_status(id, status);
 581         xfree(name);
 582 }
 583
 584 static void
 585 process_close(void)
 586 {
 587         u_int32_t id;
 588         int handle, ret, status = SSH2_FX_FAILURE;
 589
 590         id = get_int();
 591         handle = get_handle();
 592         debug3("request %u: close handle %u", id, handle);
 593         handle_log_close(handle, NULL);
 594         ret = handle_close(handle);
 595         status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
 596         send_status(id, status);
 597 }
 598
 599 static void
 600 process_read(void)
 601 {
 602         char buf[64*1024];
 603         u_int32_t id, len;
 604         int handle, fd, ret, status = SSH2_FX_FAILURE;
 605         u_int64_t off;
 606
 607         id = get_int();
 608         handle = get_handle();
 609         off = get_int64();
 610         len = get_int();
 611
 612         debug("request %u: read \"%s\" (handle %d) off %llu len %d",
 613             id, handle_to_name(handle), handle, (unsigned long long)off, len);
 614         if (len > sizeof buf) {
 615                 len = sizeof buf;
 616                 debug2("read change len %d", len);
 617         }
 618         fd = handle_to_fd(handle);
 619         if (fd >= 0) {
 620                 if (lseek(fd, off, SEEK_SET) < 0) {
 621                         error("process_read: seek failed");
 622                         status = errno_to_portable(errno);
 623                 } else {
 624                         ret = read(fd, buf, len);
 625                         if (ret < 0) {
 626                                 status = errno_to_portable(errno);
 627                         } else if (ret == 0) {
 628                                 status = SSH2_FX_EOF;
 629                         } else {
 630                                 send_data(id, buf, ret);
 631                                 status = SSH2_FX_OK;
 632                                 handle_update_read(handle, ret);
 633                         }
 634                 }
 635         }
 636         if (status != SSH2_FX_OK)
 637                 send_status(id, status);
 638 }
 639
 640 static void
 641 process_write(void)
 642 {
 643         u_int32_t id;
 644         u_int64_t off;
 645         u_int len;
 646         int handle, fd, ret, status;
 647         char *data;
 648
 649         id = get_int();
 650         handle = get_handle();
 651         off = get_int64();
 652         data = get_string(&len);
 653
 654         debug("request %u: write \"%s\" (handle %d) off %llu len %d",
 655             id, handle_to_name(handle), handle, (unsigned long long)off, len);
 656         fd = handle_to_fd(handle);
 657
 658         if (fd < 0)
 659                 status = SSH2_FX_FAILURE;
 660         else if (readonly)
 661                 status = SSH2_FX_PERMISSION_DENIED;
 662         else {
 663                 if (lseek(fd, off, SEEK_SET) < 0) {
 664                         status = errno_to_portable(errno);
 665                         error("process_write: seek failed");
 666                 } else {
 667 /* XXX ATOMICIO ? */
 668                         ret = write(fd, data, len);
 669                         if (ret < 0) {
 670                                 error("process_write: write failed");
 671                                 status = errno_to_portable(errno);
 672                         } else if ((size_t)ret == len) {
 673                                 status = SSH2_FX_OK;
 674                                 handle_update_write(handle, ret);
 675                         } else {
 676                                 debug2("nothing at all written");
 677                                 status = SSH2_FX_FAILURE;
 678                         }
 679                 }
 680         }
 681         send_status(id, status);
 682         xfree(data);
 683 }
 684
 685 static void
 686 process_do_stat(int do_lstat)
 687 {
 688         Attrib a;
 689         struct stat st;
 690         u_int32_t id;
 691         char *name;
 692         int ret, status = SSH2_FX_FAILURE;
 693
 694         id = get_int();
 695         name = get_string(NULL);
 696         debug3("request %u: %sstat", id, do_lstat ? "l" : "");
 697         verbose("%sstat name \"%s\"", do_lstat ? "l" : "", name);
 698         ret = do_lstat ? lstat(name, &st) : stat(name, &st);
 699         if (ret < 0) {
 700                 status = errno_to_portable(errno);
 701         } else {
 702                 stat_to_attrib(&st, &a);
 703                 send_attrib(id, &a);
 704                 status = SSH2_FX_OK;
 705         }
 706         if (status != SSH2_FX_OK)
 707                 send_status(id, status);
 708         xfree(name);
 709 }
 710
 711 static void
 712 process_stat(void)
 713 {
 714         process_do_stat(0);
 715 }
 716
 717 static void
 718 process_lstat(void)
 719 {
 720         process_do_stat(1);
 721 }
 722
 723 static void
 724 process_fstat(void)
 725 {
 726         Attrib a;
 727         struct stat st;
 728         u_int32_t id;
 729         int fd, ret, handle, status = SSH2_FX_FAILURE;
 730
 731         id = get_int();
 732         handle = get_handle();
 733         debug("request %u: fstat \"%s\" (handle %u)",
 734             id, handle_to_name(handle), handle);
 735         fd = handle_to_fd(handle);
 736         if (fd >= 0) {
 737                 ret = fstat(fd, &st);
 738                 if (ret < 0) {
 739                         status = errno_to_portable(errno);
 740                 } else {
 741                         stat_to_attrib(&st, &a);
 742                         send_attrib(id, &a);
 743                         status = SSH2_FX_OK;
 744                 }
 745         }
 746         if (status != SSH2_FX_OK)
 747                 send_status(id, status);
 748 }
 749
 750 static struct timeval *
 751 attrib_to_tv(const Attrib *a)
 752 {
 753         static struct timeval tv[2];
 754
 755         tv[0].tv_sec = a->atime;
 756         tv[0].tv_usec = 0;
 757         tv[1].tv_sec = a->mtime;
 758         tv[1].tv_usec = 0;
 759         return tv;
 760 }
 761
 762 static void
 763 process_setstat(void)
 764 {
 765         Attrib *a;
 766         u_int32_t id;
 767         char *name;
 768         int status = SSH2_FX_OK, ret;
 769
 770         id = get_int();
 771         name = get_string(NULL);
 772         a = get_attrib();
 773         debug("request %u: setstat name \"%s\"", id, name);
 774         if (readonly) {
 775                 status = SSH2_FX_PERMISSION_DENIED;
 776                 a->flags = 0;
 777         }
 778         if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
 779                 logit("set \"%s\" size %llu",
 780                     name, (unsigned long long)a->size);
 781                 ret = truncate(name, a->size);
 782                 if (ret == -1)
 783                         status = errno_to_portable(errno);
 784         }
 785         if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
 786                 logit("set \"%s\" mode %04o", name, a->perm);
 787                 ret = chmod(name, a->perm & 07777);
 788                 if (ret == -1)
 789                         status = errno_to_portable(errno);
 790         }
 791         if (a->flags & SSH2_FILEXFER_ATTR_ACMODTIME) {
 792                 char buf[64];
 793                 time_t t = a->mtime;
 794
 795                 strftime(buf, sizeof(buf), "%Y%m%d-%H:%M:%S",
 796                     localtime(&t));
 797                 logit("set \"%s\" modtime %s", name, buf);
 798                 ret = utimes(name, attrib_to_tv(a));
 799                 if (ret == -1)
 800                         status = errno_to_portable(errno);
 801         }
 802         if (a->flags & SSH2_FILEXFER_ATTR_UIDGID) {
 803                 logit("set \"%s\" owner %lu group %lu", name,
 804                     (u_long)a->uid, (u_long)a->gid);
 805                 ret = chown(name, a->uid, a->gid);
 806                 if (ret == -1)
 807                         status = errno_to_portable(errno);
 808         }
 809         send_status(id, status);
 810         xfree(name);
 811 }
 812
 813 static void
 814 process_fsetstat(void)
 815 {
 816         Attrib *a;
 817         u_int32_t id;
 818         int handle, fd, ret;
 819         int status = SSH2_FX_OK;
 820
 821         id = get_int();
 822         handle = get_handle();
 823         a = get_attrib();
 824         debug("request %u: fsetstat handle %d", id, handle);
 825         fd = handle_to_fd(handle);
 826         if (fd < 0)
 827                 status = SSH2_FX_FAILURE;
 828         else if (readonly)
 829                 status = SSH2_FX_PERMISSION_DENIED;
 830         else {
 831                 char *name = handle_to_name(handle);
 832
 833                 if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
 834                         logit("set \"%s\" size %llu",
 835                             name, (unsigned long long)a->size);
 836                         ret = ftruncate(fd, a->size);
 837                         if (ret == -1)
 838                                 status = errno_to_portable(errno);
 839                 }
 840                 if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
 841                         logit("set \"%s\" mode %04o", name, a->perm);
 842 #ifdef HAVE_FCHMOD
 843                         ret = fchmod(fd, a->perm & 07777);
 844 #else
 845                         ret = chmod(name, a->perm & 07777);
 846 #endif
 847                         if (ret == -1)
 848                                 status = errno_to_portable(errno);
 849                 }
 850                 if (a->flags & SSH2_FILEXFER_ATTR_ACMODTIME) {
 851                         char buf[64];
 852                         time_t t = a->mtime;
 853
 854                         strftime(buf, sizeof(buf), "%Y%m%d-%H:%M:%S",
 855                             localtime(&t));
 856                         logit("set \"%s\" modtime %s", name, buf);
 857 #ifdef HAVE_FUTIMES
 858                         ret = futimes(fd, attrib_to_tv(a));
 859 #else
 860                         ret = utimes(name, attrib_to_tv(a));
 861 #endif
 862                         if (ret == -1)
 863                                 status = errno_to_portable(errno);
 864                 }
 865                 if (a->flags & SSH2_FILEXFER_ATTR_UIDGID) {
 866                         logit("set \"%s\" owner %lu group %lu", name,
 867                             (u_long)a->uid, (u_long)a->gid);
 868 #ifdef HAVE_FCHOWN
 869                         ret = fchown(fd, a->uid, a->gid);
 870 #else
 871                         ret = chown(name, a->uid, a->gid);
 872 #endif
 873                         if (ret == -1)
 874                                 status = errno_to_portable(errno);
 875                 }
 876         }
 877         send_status(id, status);
 878 }
 879
 880 static void
 881 process_opendir(void)
 882 {
 883         DIR *dirp = NULL;
 884         char *path;
 885         int handle, status = SSH2_FX_FAILURE;
 886         u_int32_t id;
 887
 888         id = get_int();
 889         path = get_string(NULL);
 890         debug3("request %u: opendir", id);
 891         logit("opendir \"%s\"", path);
 892         dirp = opendir(path);
 893         if (dirp == NULL) {
 894                 status = errno_to_portable(errno);
 895         } else {
 896                 handle = handle_new(HANDLE_DIR, path, 0, dirp);
 897                 if (handle < 0) {
 898                         closedir(dirp);
 899                 } else {
 900                         send_handle(id, handle);
 901                         status = SSH2_FX_OK;
 902                 }
 903
 904         }
 905         if (status != SSH2_FX_OK)
 906                 send_status(id, status);
 907         xfree(path);
 908 }
 909
 910 static void
 911 process_readdir(void)
 912 {
 913         DIR *dirp;
 914         struct dirent *dp;
 915         char *path;
 916         int handle;
 917         u_int32_t id;
 918
 919         id = get_int();
 920         handle = get_handle();
 921         debug("request %u: readdir \"%s\" (handle %d)", id,
 922             handle_to_name(handle), handle);
 923         dirp = handle_to_dir(handle);
 924         path = handle_to_name(handle);
 925         if (dirp == NULL || path == NULL) {
 926                 send_status(id, SSH2_FX_FAILURE);
 927         } else {
 928                 struct stat st;
 929                 char pathname[MAXPATHLEN];
 930                 Stat *stats;
 931                 int nstats = 10, count = 0, i;
 932
 933                 stats = xcalloc(nstats, sizeof(Stat));
 934                 while ((dp = readdir(dirp)) != NULL) {
 935                         if (count >= nstats) {
 936                                 nstats *= 2;
 937                                 stats = xrealloc(stats, nstats, sizeof(Stat));
 938                         }
 939 /* XXX OVERFLOW ? */
 940                         snprintf(pathname, sizeof pathname, "%s%s%s", path,
 941                             strcmp(path, "/") ? "/" : "", dp->d_name);
 942                         if (lstat(pathname, &st) < 0)
 943                                 continue;
 944                         stat_to_attrib(&st, &(stats[count].attrib));
 945                         stats[count].name = xstrdup(dp->d_name);
 946                         stats[count].long_name = ls_file(dp->d_name, &st, 0, 0);
 947                         count++;
 948                         /* send up to 100 entries in one message */
 949                         /* XXX check packet size instead */
 950                         if (count == 100)
 951                                 break;
 952                 }
 953                 if (count > 0) {
 954                         send_names(id, count, stats);
 955                         for (i = 0; i < count; i++) {
 956                                 xfree(stats[i].name);
 957                                 xfree(stats[i].long_name);
 958                         }
 959                 } else {
 960                         send_status(id, SSH2_FX_EOF);
 961                 }
 962                 xfree(stats);
 963         }
 964 }
 965
 966 static void
 967 process_remove(void)
 968 {
 969         char *name;
 970         u_int32_t id;
 971         int status = SSH2_FX_FAILURE;
 972         int ret;
 973
 974         id = get_int();
 975         name = get_string(NULL);
 976         debug3("request %u: remove", id);
 977         logit("remove name \"%s\"", name);
 978         if (readonly)
 979                 status = SSH2_FX_PERMISSION_DENIED;
 980         else {
 981                 ret = unlink(name);
 982                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
 983         }
 984         send_status(id, status);
 985         xfree(name);
 986 }
 987
 988 static void
 989 process_mkdir(void)
 990 {
 991         Attrib *a;
 992         u_int32_t id;
 993         char *name;
 994         int ret, mode, status = SSH2_FX_FAILURE;
 995
 996         id = get_int();
 997         name = get_string(NULL);
 998         a = get_attrib();
 999         mode = (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ?
1000             a->perm & 07777 : 0777;
1001         debug3("request %u: mkdir", id);
1002         logit("mkdir name \"%s\" mode 0%o", name, mode);
1003         if (readonly)
1004                 status = SSH2_FX_PERMISSION_DENIED;
1005         else {
1006                 ret = mkdir(name, mode);
1007                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1008         }
1009         send_status(id, status);
1010         xfree(name);
1011 }
1012
1013 static void
1014 process_rmdir(void)
1015 {
1016         u_int32_t id;
1017         char *name;
1018         int ret, status;
1019
1020         id = get_int();
1021         name = get_string(NULL);
1022         debug3("request %u: rmdir", id);
1023         logit("rmdir name \"%s\"", name);
1024         if (readonly)
1025                 status = SSH2_FX_PERMISSION_DENIED;
1026         else {
1027                 ret = rmdir(name);
1028                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1029         }
1030         send_status(id, status);
1031         xfree(name);
1032 }
1033
1034 static void
1035 process_realpath(void)
1036 {
1037         char resolvedname[MAXPATHLEN];
1038         u_int32_t id;
1039         char *path;
1040
1041         id = get_int();
1042         path = get_string(NULL);
1043         if (path[0] == '\0') {
1044                 xfree(path);
1045                 path = xstrdup(".");
1046         }
1047         debug3("request %u: realpath", id);
1048         verbose("realpath \"%s\"", path);
1049         if (realpath(path, resolvedname) == NULL) {
1050                 send_status(id, errno_to_portable(errno));
1051         } else {
1052                 Stat s;
1053                 attrib_clear(&s.attrib);
1054                 s.name = s.long_name = resolvedname;
1055                 send_names(id, 1, &s);
1056         }
1057         xfree(path);
1058 }
1059
1060 static void
1061 process_rename(void)
1062 {
1063         u_int32_t id;
1064         char *oldpath, *newpath;
1065         int status;
1066         struct stat sb;
1067
1068         id = get_int();
1069         oldpath = get_string(NULL);
1070         newpath = get_string(NULL);
1071         debug3("request %u: rename", id);
1072         logit("rename old \"%s\" new \"%s\"", oldpath, newpath);
1073         status = SSH2_FX_FAILURE;
1074         if (readonly)
1075                 status = SSH2_FX_PERMISSION_DENIED;
1076         else if (lstat(oldpath, &sb) == -1)
1077                 status = errno_to_portable(errno);
1078         else if (S_ISREG(sb.st_mode)) {
1079                 /* Race-free rename of regular files */
1080                 if (link(oldpath, newpath) == -1) {
1081                         if (errno == EOPNOTSUPP || errno == ENOSYS
1082 #ifdef EXDEV
1083                             || errno == EXDEV
1084 #endif
1085 #ifdef LINK_OPNOTSUPP_ERRNO
1086                             || errno == LINK_OPNOTSUPP_ERRNO
1087 #endif
1088                             ) {
1089                                 struct stat st;
1090
1091                                 /*
1092                                  * fs doesn't support links, so fall back to
1093                                  * stat+rename.  This is racy.
1094                                  */
1095                                 if (stat(newpath, &st) == -1) {
1096                                         if (rename(oldpath, newpath) == -1)
1097                                                 status =
1098                                                     errno_to_portable(errno);
1099                                         else
1100                                                 status = SSH2_FX_OK;
1101                                 }
1102                         } else {
1103                                 status = errno_to_portable(errno);
1104                         }
1105                 } else if (unlink(oldpath) == -1) {
1106                         status = errno_to_portable(errno);
1107                         /* clean spare link */
1108                         unlink(newpath);
1109                 } else
1110                         status = SSH2_FX_OK;
1111         } else if (stat(newpath, &sb) == -1) {
1112                 if (rename(oldpath, newpath) == -1)
1113                         status = errno_to_portable(errno);
1114                 else
1115                         status = SSH2_FX_OK;
1116         }
1117         send_status(id, status);
1118         xfree(oldpath);
1119         xfree(newpath);
1120 }
1121
1122 static void
1123 process_readlink(void)
1124 {
1125         u_int32_t id;
1126         int len;
1127         char buf[MAXPATHLEN];
1128         char *path;
1129
1130         id = get_int();
1131         path = get_string(NULL);
1132         debug3("request %u: readlink", id);
1133         verbose("readlink \"%s\"", path);
1134         if ((len = readlink(path, buf, sizeof(buf) - 1)) == -1)
1135                 send_status(id, errno_to_portable(errno));
1136         else {
1137                 Stat s;
1138
1139                 buf[len] = '\0';
1140                 attrib_clear(&s.attrib);
1141                 s.name = s.long_name = buf;
1142                 send_names(id, 1, &s);
1143         }
1144         xfree(path);
1145 }
1146
1147 static void
1148 process_symlink(void)
1149 {
1150         u_int32_t id;
1151         char *oldpath, *newpath;
1152         int ret, status;
1153
1154         id = get_int();
1155         oldpath = get_string(NULL);
1156         newpath = get_string(NULL);
1157         debug3("request %u: symlink", id);
1158         logit("symlink old \"%s\" new \"%s\"", oldpath, newpath);
1159         /* this will fail if 'newpath' exists */
1160         if (readonly)
1161                 status = SSH2_FX_PERMISSION_DENIED;
1162         else {
1163                 ret = symlink(oldpath, newpath);
1164                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1165         }
1166         send_status(id, status);
1167         xfree(oldpath);
1168         xfree(newpath);
1169 }
1170
1171 static void
1172 process_extended_posix_rename(u_int32_t id)
1173 {
1174         char *oldpath, *newpath;
1175         int ret, status;
1176
1177         oldpath = get_string(NULL);
1178         newpath = get_string(NULL);
1179         debug3("request %u: posix-rename", id);
1180         logit("posix-rename old \"%s\" new \"%s\"", oldpath, newpath);
1181         if (readonly)
1182                 status = SSH2_FX_PERMISSION_DENIED;
1183         else {
1184                 ret = rename(oldpath, newpath);
1185                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1186         }
1187         send_status(id, status);
1188         xfree(oldpath);
1189         xfree(newpath);
1190 }
1191
1192 static void
1193 process_extended_statvfs(u_int32_t id)
1194 {
1195         char *path;
1196         struct statvfs st;
1197
1198         path = get_string(NULL);
1199         debug3("request %u: statfs", id);
1200         logit("statfs \"%s\"", path);
1201
1202         if (statvfs(path, &st) != 0)
1203                 send_status(id, errno_to_portable(errno));
1204         else
1205                 send_statvfs(id, &st);
1206         xfree(path);
1207 }
1208
1209 static void
1210 process_extended_fstatvfs(u_int32_t id)
1211 {
1212         int handle, fd;
1213         struct statvfs st;
1214
1215         handle = get_handle();
1216         debug("request %u: fstatvfs \"%s\" (handle %u)",
1217             id, handle_to_name(handle), handle);
1218         if ((fd = handle_to_fd(handle)) < 0) {
1219                 send_status(id, SSH2_FX_FAILURE);
1220                 return;
1221         }
1222         if (fstatvfs(fd, &st) != 0)
1223                 send_status(id, errno_to_portable(errno));
1224         else
1225                 send_statvfs(id, &st);
1226 }
1227
1228 static void
1229 process_extended_hardlink(u_int32_t id)
1230 {
1231         char *oldpath, *newpath;
1232         int ret, status;
1233
1234         oldpath = get_string(NULL);
1235         newpath = get_string(NULL);
1236         debug3("request %u: hardlink", id);
1237         logit("hardlink old \"%s\" new \"%s\"", oldpath, newpath);
1238         if (readonly)
1239                 status = SSH2_FX_PERMISSION_DENIED;
1240         else {
1241                 ret = link(oldpath, newpath);
1242                 status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
1243         }
1244         send_status(id, status);
1245         xfree(oldpath);
1246         xfree(newpath);
1247 }
1248
1249 static void
1250 process_extended(void)
1251 {
1252         u_int32_t id;
1253         char *request;
1254
1255         id = get_int();
1256         request = get_string(NULL);
1257         if (strcmp(request, "posix-rename@openssh.com") == 0)
1258                 process_extended_posix_rename(id);
1259         else if (strcmp(request, "statvfs@openssh.com") == 0)
1260                 process_extended_statvfs(id);
1261         else if (strcmp(request, "fstatvfs@openssh.com") == 0)
1262                 process_extended_fstatvfs(id);
1263         else if (strcmp(request, "hardlink@openssh.com") == 0)
1264                 process_extended_hardlink(id);
1265         else
1266                 send_status(id, SSH2_FX_OP_UNSUPPORTED);        /* MUST */
1267         xfree(request);
1268 }
1269
1270 /* stolen from ssh-agent */
1271
1272 static void
1273 process(void)
1274 {
1275         u_int msg_len;
1276         u_int buf_len;
1277         u_int consumed;
1278         u_int type;
1279         u_char *cp;
1280
1281         buf_len = buffer_len(&iqueue);
1282         if (buf_len < 5)
1283                 return;         /* Incomplete message. */
1284         cp = buffer_ptr(&iqueue);
1285         msg_len = get_u32(cp);
1286         if (msg_len > SFTP_MAX_MSG_LENGTH) {
1287                 error("bad message from %s local user %s",
1288                     client_addr, pw->pw_name);
1289                 sftp_server_cleanup_exit(11);
1290         }
1291         if (buf_len < msg_len + 4)
1292                 return;
1293         buffer_consume(&iqueue, 4);
1294         buf_len -= 4;
1295         type = buffer_get_char(&iqueue);
1296         switch (type) {
1297         case SSH2_FXP_INIT:
1298                 process_init();
1299                 break;
1300         case SSH2_FXP_OPEN:
1301                 process_open();
1302                 break;
1303         case SSH2_FXP_CLOSE:
1304                 process_close();
1305                 break;
1306         case SSH2_FXP_READ:
1307                 process_read();
1308                 break;
1309         case SSH2_FXP_WRITE:
1310                 process_write();
1311                 break;
1312         case SSH2_FXP_LSTAT:
1313                 process_lstat();
1314                 break;
1315         case SSH2_FXP_FSTAT:
1316                 process_fstat();
1317                 break;
1318         case SSH2_FXP_SETSTAT:
1319                 process_setstat();
1320                 break;
1321         case SSH2_FXP_FSETSTAT:
1322                 process_fsetstat();
1323                 break;
1324         case SSH2_FXP_OPENDIR:
1325                 process_opendir();
1326                 break;
1327         case SSH2_FXP_READDIR:
1328                 process_readdir();
1329                 break;
1330         case SSH2_FXP_REMOVE:
1331                 process_remove();
1332                 break;
1333         case SSH2_FXP_MKDIR:
1334                 process_mkdir();
1335                 break;
1336         case SSH2_FXP_RMDIR:
1337                 process_rmdir();
1338                 break;
1339         case SSH2_FXP_REALPATH:
1340                 process_realpath();
1341                 break;
1342         case SSH2_FXP_STAT:
1343                 process_stat();
1344                 break;
1345         case SSH2_FXP_RENAME:
1346                 process_rename();
1347                 break;
1348         case SSH2_FXP_READLINK:
1349                 process_readlink();
1350                 break;
1351         case SSH2_FXP_SYMLINK:
1352                 process_symlink();
1353                 break;
1354         case SSH2_FXP_EXTENDED:
1355                 process_extended();
1356                 break;
1357         default:
1358                 error("Unknown message %d", type);
1359                 break;
1360         }
1361         /* discard the remaining bytes from the current packet */
1362         if (buf_len < buffer_len(&iqueue)) {
1363                 error("iqueue grew unexpectedly");
1364                 sftp_server_cleanup_exit(255);
1365         }
1366         consumed = buf_len - buffer_len(&iqueue);
1367         if (msg_len < consumed) {
1368                 error("msg_len %d < consumed %d", msg_len, consumed);
1369                 sftp_server_cleanup_exit(255);
1370         }
1371         if (msg_len > consumed)
1372                 buffer_consume(&iqueue, msg_len - consumed);
1373 }
1374
1375 /* Cleanup handler that logs active handles upon normal exit */
1376 void
1377 sftp_server_cleanup_exit(int i)
1378 {
1379         if (pw != NULL && client_addr != NULL) {
1380                 handle_log_exit();
1381                 logit("session closed for local user %s from [%s]",
1382                     pw->pw_name, client_addr);
1383         }
1384         _exit(i);
1385 }
1386
1387 static void
1388 sftp_server_usage(void)
1389 {
1390         extern char *__progname;
1391
1392         fprintf(stderr,
1393             "usage: %s [-ehR] [-f log_facility] [-l log_level] [-u umask]\n",
1394             __progname);
1395         exit(1);
1396 }
1397
1398 int
1399 sftp_server_main(int argc, char **argv, struct passwd *user_pw)
1400 {
1401         fd_set *rset, *wset;
1402         int in, out, max, ch, skipargs = 0, log_stderr = 0;
1403         ssize_t len, olen, set_size;
1404         SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
1405         char *cp, buf[4*4096];
1406         long mask;
1407
1408         extern char *optarg;
1409         extern char *__progname;
1410
1411         __progname = ssh_get_progname(argv[0]);
1412         log_init(__progname, log_level, log_facility, log_stderr);
1413
1414         while (!skipargs && (ch = getopt(argc, argv, "f:l:u:cehR")) != -1) {
1415                 switch (ch) {
1416                 case 'R':
1417                         readonly = 1;
1418                         break;
1419                 case 'c':
1420                         /*
1421                          * Ignore all arguments if we are invoked as a
1422                          * shell using "sftp-server -c command"
1423                          */
1424                         skipargs = 1;
1425                         break;
1426                 case 'e':
1427                         log_stderr = 1;
1428                         break;
1429                 case 'l':
1430                         log_level = log_level_number(optarg);
1431                         if (log_level == SYSLOG_LEVEL_NOT_SET)
1432                                 error("Invalid log level \"%s\"", optarg);
1433                         break;
1434                 case 'f':
1435                         log_facility = log_facility_number(optarg);
1436                         if (log_facility == SYSLOG_FACILITY_NOT_SET)
1437                                 error("Invalid log facility \"%s\"", optarg);
1438                         break;
1439                 case 'u':
1440                         errno = 0;
1441                         mask = strtol(optarg, &cp, 8);
1442                         if (mask < 0 || mask > 0777 || *cp != '\0' ||
1443                             cp == optarg || (mask == 0 && errno != 0))
1444                                 fatal("Invalid umask \"%s\"", optarg);
1445                         (void)umask((mode_t)mask);
1446                         break;
1447                 case 'h':
1448                 default:
1449                         sftp_server_usage();
1450                 }
1451         }
1452
1453         log_init(__progname, log_level, log_facility, log_stderr);
1454
1455         if ((cp = getenv("SSH_CONNECTION")) != NULL) {
1456                 client_addr = xstrdup(cp);
1457                 if ((cp = strchr(client_addr, ' ')) == NULL) {
1458                         error("Malformed SSH_CONNECTION variable: \"%s\"",
1459                             getenv("SSH_CONNECTION"));
1460                         sftp_server_cleanup_exit(255);
1461                 }
1462                 *cp = '\0';
1463         } else
1464                 client_addr = xstrdup("UNKNOWN");
1465
1466         pw = pwcopy(user_pw);
1467
1468         logit("session opened for local user %s from [%s]",
1469             pw->pw_name, client_addr);
1470
1471         in = STDIN_FILENO;
1472         out = STDOUT_FILENO;
1473
1474 #ifdef HAVE_CYGWIN
1475         setmode(in, O_BINARY);
1476         setmode(out, O_BINARY);
1477 #endif
1478
1479         max = 0;
1480         if (in > max)
1481                 max = in;
1482         if (out > max)
1483                 max = out;
1484
1485         buffer_init(&iqueue);
1486         buffer_init(&oqueue);
1487
1488         set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
1489         rset = (fd_set *)xmalloc(set_size);
1490         wset = (fd_set *)xmalloc(set_size);
1491
1492         for (;;) {
1493                 memset(rset, 0, set_size);
1494                 memset(wset, 0, set_size);
1495
1496                 /*
1497                  * Ensure that we can read a full buffer and handle
1498                  * the worst-case length packet it can generate,
1499                  * otherwise apply backpressure by stopping reads.
1500                  */
1501                 if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
1502                     buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
1503                         FD_SET(in, rset);
1504
1505                 olen = buffer_len(&oqueue);
1506                 if (olen > 0)
1507                         FD_SET(out, wset);
1508
1509                 if (select(max+1, rset, wset, NULL, NULL) < 0) {
1510                         if (errno == EINTR)
1511                                 continue;
1512                         error("select: %s", strerror(errno));
1513                         sftp_server_cleanup_exit(2);
1514                 }
1515
1516                 /* copy stdin to iqueue */
1517                 if (FD_ISSET(in, rset)) {
1518                         len = read(in, buf, sizeof buf);
1519                         if (len == 0) {
1520                                 debug("read eof");
1521                                 sftp_server_cleanup_exit(0);
1522                         } else if (len < 0) {
1523                                 error("read: %s", strerror(errno));
1524                                 sftp_server_cleanup_exit(1);
1525                         } else {
1526                                 buffer_append(&iqueue, buf, len);
1527                         }
1528                 }
1529                 /* send oqueue to stdout */
1530                 if (FD_ISSET(out, wset)) {
1531                         len = write(out, buffer_ptr(&oqueue), olen);
1532                         if (len < 0) {
1533                                 error("write: %s", strerror(errno));
1534                                 sftp_server_cleanup_exit(1);
1535                         } else {
1536                                 buffer_consume(&oqueue, len);
1537                         }
1538                 }
1539
1540                 /*
1541                  * Process requests from client if we can fit the results
1542                  * into the output buffer, otherwise stop processing input
1543                  * and let the output queue drain.
1544                  */
1545                 if (buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
1546                         process();
1547         }
1548 }