Exemple #1
0
int
sftp_server_main(int argc, char **argv, struct passwd *user_pw)
{
	fd_set *rset, *wset;
	int i, r, in, out, max, ch, skipargs = 0, log_stderr = 0;
	ssize_t len, olen, set_size;
	SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
	char *cp, *homedir = NULL, buf[4*4096];
	long mask;

	extern char *optarg;
	extern char *__progname;

	ssh_malloc_init();	/* must be called before any mallocs */
	__progname = ssh_get_progname(argv[0]);
	log_init(__progname, log_level, log_facility, log_stderr);

	pw = pwcopy(user_pw);

	while (!skipargs && (ch = getopt(argc, argv,
	    "d:f:l:P:p:Q:u:cehR")) != -1) {
		switch (ch) {
		case 'Q':
			if (strcasecmp(optarg, "requests") != 0) {
				fprintf(stderr, "Invalid query type\n");
				exit(1);
			}
			for (i = 0; handlers[i].handler != NULL; i++)
				printf("%s\n", handlers[i].name);
			for (i = 0; extended_handlers[i].handler != NULL; i++)
				printf("%s\n", extended_handlers[i].name);
			exit(0);
			break;
		case 'R':
			readonly = 1;
			break;
		case 'c':
			/*
			 * Ignore all arguments if we are invoked as a
			 * shell using "sftp-server -c command"
			 */
			skipargs = 1;
			break;
		case 'e':
			log_stderr = 1;
			break;
		case 'l':
			log_level = log_level_number(optarg);
			if (log_level == SYSLOG_LEVEL_NOT_SET)
				error("Invalid log level \"%s\"", optarg);
			break;
		case 'f':
			log_facility = log_facility_number(optarg);
			if (log_facility == SYSLOG_FACILITY_NOT_SET)
				error("Invalid log facility \"%s\"", optarg);
			break;
		case 'd':
			cp = tilde_expand_filename(optarg, user_pw->pw_uid);
			homedir = percent_expand(cp, "d", user_pw->pw_dir,
			    "u", user_pw->pw_name, (char *)NULL);
			free(cp);
			break;
		case 'p':
			if (request_whitelist != NULL)
				fatal("Permitted requests already set");
			request_whitelist = xstrdup(optarg);
			break;
		case 'P':
			if (request_blacklist != NULL)
				fatal("Refused requests already set");
			request_blacklist = xstrdup(optarg);
			break;
		case 'u':
			errno = 0;
			mask = strtol(optarg, &cp, 8);
			if (mask < 0 || mask > 0777 || *cp != '\0' ||
			    cp == optarg || (mask == 0 && errno != 0))
				fatal("Invalid umask \"%s\"", optarg);
			(void)umask((mode_t)mask);
			break;
		case 'h':
		default:
			sftp_server_usage();
		}
	}

	log_init(__progname, log_level, log_facility, log_stderr);

#if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
	/*
	 * On Linux, we should try to avoid making /proc/self/{mem,maps}
	 * available to the user so that sftp access doesn't automatically
	 * imply arbitrary code execution access that will break
	 * restricted configurations.
	 */
	if (prctl(PR_SET_DUMPABLE, 0) != 0)
		fatal("unable to make the process undumpable");
#endif /* defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) */

	/* Drop any fine-grained privileges we don't need */
	platform_pledge_sftp_server();

	if ((cp = getenv("SSH_CONNECTION")) != NULL) {
		client_addr = xstrdup(cp);
		if ((cp = strchr(client_addr, ' ')) == NULL) {
			error("Malformed SSH_CONNECTION variable: \"%s\"",
			    getenv("SSH_CONNECTION"));
			sftp_server_cleanup_exit(255);
		}
		*cp = '\0';
	} else
		client_addr = xstrdup("UNKNOWN");

	logit("session opened for local user %s from [%s]",
	    pw->pw_name, client_addr);

	in = STDIN_FILENO;
	out = STDOUT_FILENO;

#ifdef HAVE_CYGWIN
	setmode(in, O_BINARY);
	setmode(out, O_BINARY);
#endif

	max = 0;
	if (in > max)
		max = in;
	if (out > max)
		max = out;

	if ((iqueue = sshbuf_new()) == NULL)
		fatal("%s: sshbuf_new failed", __func__);
	if ((oqueue = sshbuf_new()) == NULL)
		fatal("%s: sshbuf_new failed", __func__);

	rset = xcalloc(howmany(max + 1, NFDBITS), sizeof(fd_mask));
	wset = xcalloc(howmany(max + 1, NFDBITS), sizeof(fd_mask));

	if (homedir != NULL) {
		if (chdir(homedir) != 0) {
			error("chdir to \"%s\" failed: %s", homedir,
			    strerror(errno));
		}
	}

	set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
	for (;;) {
		memset(rset, 0, set_size);
		memset(wset, 0, set_size);

		/*
		 * Ensure that we can read a full buffer and handle
		 * the worst-case length packet it can generate,
		 * otherwise apply backpressure by stopping reads.
		 */
		if ((r = sshbuf_check_reserve(iqueue, sizeof(buf))) == 0 &&
		    (r = sshbuf_check_reserve(oqueue,
		    SFTP_MAX_MSG_LENGTH)) == 0)
			FD_SET(in, rset);
		else if (r != SSH_ERR_NO_BUFFER_SPACE)
			fatal("%s: sshbuf_check_reserve failed: %s",
			    __func__, ssh_err(r));

		olen = sshbuf_len(oqueue);
		if (olen > 0)
			FD_SET(out, wset);

		if (select(max+1, rset, wset, NULL, NULL) < 0) {
			if (errno == EINTR)
				continue;
			error("select: %s", strerror(errno));
			sftp_server_cleanup_exit(2);
		}

		/* copy stdin to iqueue */
		if (FD_ISSET(in, rset)) {
			len = read(in, buf, sizeof buf);
			if (len == 0) {
				debug("read eof");
				sftp_server_cleanup_exit(0);
			} else if (len < 0) {
				error("read: %s", strerror(errno));
				sftp_server_cleanup_exit(1);
			} else if ((r = sshbuf_put(iqueue, buf, len)) != 0) {
				fatal("%s: buffer error: %s",
				    __func__, ssh_err(r));
			}
		}
		/* send oqueue to stdout */
		if (FD_ISSET(out, wset)) {
			len = write(out, sshbuf_ptr(oqueue), olen);
			if (len < 0) {
				error("write: %s", strerror(errno));
				sftp_server_cleanup_exit(1);
			} else if ((r = sshbuf_consume(oqueue, len)) != 0) {
				fatal("%s: buffer error: %s",
				    __func__, ssh_err(r));
			}
		}

		/*
		 * Process requests from client if we can fit the results
		 * into the output buffer, otherwise stop processing input
		 * and let the output queue drain.
		 */
		r = sshbuf_check_reserve(oqueue, SFTP_MAX_MSG_LENGTH);
		if (r == 0)
			process();
		else if (r != SSH_ERR_NO_BUFFER_SPACE)
			fatal("%s: sshbuf_check_reserve: %s",
			    __func__, ssh_err(r));
	}
}
Exemple #2
0
void
cleanup_exit(int i)
{
	sftp_server_cleanup_exit(i);
}
int
sftp_server_main(int argc, char **argv, struct passwd *user_pw)
{
	fd_set *rset, *wset;
	int in, out, max, ch, skipargs = 0, log_stderr = 0;
	ssize_t len, olen, set_size;
	SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
	char *cp, buf[4*4096];
	const char *errmsg;
	mode_t mask;

	extern char *optarg;
	extern char *__progname;

	__progname = ssh_get_progname(argv[0]);
	log_init(__progname, log_level, log_facility, log_stderr);

    fake_permissions = 0;
	while (!skipargs && (ch = getopt(argc, argv, "f:l:u:cehRU")) != -1) {
		switch (ch) {
		case 'R':
			readonly = 1;
			break;
		case 'c':
			/*
			 * Ignore all arguments if we are invoked as a
			 * shell using "sftp-server -c command"
			 */
			skipargs = 1;
			break;
		case 'e':
			log_stderr = 1;
			break;
		case 'l':
			log_level = log_level_number(optarg);
			if (log_level == SYSLOG_LEVEL_NOT_SET)
				error("Invalid log level \"%s\"", optarg);
			break;
		case 'f':
			log_facility = log_facility_number(optarg);
			if (log_facility == SYSLOG_FACILITY_NOT_SET)
				error("Invalid log facility \"%s\"", optarg);
			break;
		case 'u':
			mask = (mode_t)strtonum(optarg, 0, 0777, &errmsg);
			if (errmsg != NULL)
				fatal("Invalid umask \"%s\": %s",
				    optarg, errmsg);
			(void)umask(mask);
			break;
		case 'U': /* Fake permissions */
			fake_permissions = 1;
			break;
		case 'h':
		default:
			sftp_server_usage();
		}
	}

	log_init(__progname, log_level, log_facility, log_stderr);

	if ((cp = getenv("SSH_CONNECTION")) != NULL) {
		client_addr = xstrdup(cp);
		if ((cp = strchr(client_addr, ' ')) == NULL) {
			error("Malformed SSH_CONNECTION variable: \"%s\"",
			    getenv("SSH_CONNECTION"));
			sftp_server_cleanup_exit(255);
		}
		*cp = '\0';
	} else
		client_addr = xstrdup("UNKNOWN");

	pw = pwcopy(user_pw);

	logit("session opened for local user %s from [%s]",
	    pw->pw_name, client_addr);

	in = STDIN_FILENO;
	out = STDOUT_FILENO;

#ifdef HAVE_CYGWIN
	setmode(in, O_BINARY);
	setmode(out, O_BINARY);
#endif

	max = 0;
	if (in > max)
		max = in;
	if (out > max)
		max = out;

	buffer_init(&iqueue);
	buffer_init(&oqueue);

	set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
	rset = (fd_set *)xmalloc(set_size);
	wset = (fd_set *)xmalloc(set_size);

	for (;;) {
		memset(rset, 0, set_size);
		memset(wset, 0, set_size);

		/*
		 * Ensure that we can read a full buffer and handle
		 * the worst-case length packet it can generate,
		 * otherwise apply backpressure by stopping reads.
		 */
		if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
		    buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
			FD_SET(in, rset);

		olen = buffer_len(&oqueue);
		if (olen > 0)
			FD_SET(out, wset);

		if (select(max+1, rset, wset, NULL, NULL) < 0) {
			if (errno == EINTR)
				continue;
			error("select: %s", strerror(errno));
			sftp_server_cleanup_exit(2);
		}

		/* copy stdin to iqueue */
		if (FD_ISSET(in, rset)) {
			len = read(in, buf, sizeof buf);
			if (len == 0) {
				debug("read eof");
				sftp_server_cleanup_exit(0);
			} else if (len < 0) {
				error("read: %s", strerror(errno));
				sftp_server_cleanup_exit(1);
			} else {
				buffer_append(&iqueue, buf, len);
			}
		}
		/* send oqueue to stdout */
		if (FD_ISSET(out, wset)) {
			len = write(out, buffer_ptr(&oqueue), olen);
			if (len < 0) {
				error("write: %s", strerror(errno));
				sftp_server_cleanup_exit(1);
			} else {
				buffer_consume(&oqueue, len);
			}
		}

		/*
		 * Process requests from client if we can fit the results
		 * into the output buffer, otherwise stop processing input
		 * and let the output queue drain.
		 */
		if (buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
			process();
	}
}
Exemple #4
0
static void
process(void)
{
	u_int msg_len;
	u_int buf_len;
	u_int consumed;
	u_char type;
	const u_char *cp;
	int i, r;
	u_int32_t id;

	buf_len = sshbuf_len(iqueue);
	if (buf_len < 5)
		return;		/* Incomplete message. */
	cp = sshbuf_ptr(iqueue);
	msg_len = get_u32(cp);
	if (msg_len > SFTP_MAX_MSG_LENGTH) {
		error("bad message from %s local user %s",
		    client_addr, pw->pw_name);
		sftp_server_cleanup_exit(11);
	}
	if (buf_len < msg_len + 4)
		return;
	if ((r = sshbuf_consume(iqueue, 4)) != 0)
		fatal("%s: buffer error: %s", __func__, ssh_err(r));
	buf_len -= 4;
	if ((r = sshbuf_get_u8(iqueue, &type)) != 0)
		fatal("%s: buffer error: %s", __func__, ssh_err(r));

	switch (type) {
	case SSH2_FXP_INIT:
		process_init();
		init_done = 1;
		break;
	case SSH2_FXP_EXTENDED:
		if (!init_done)
			fatal("Received extended request before init");
		if ((r = sshbuf_get_u32(iqueue, &id)) != 0)
			fatal("%s: buffer error: %s", __func__, ssh_err(r));
		process_extended(id);
		break;
	default:
		if (!init_done)
			fatal("Received %u request before init", type);
		if ((r = sshbuf_get_u32(iqueue, &id)) != 0)
			fatal("%s: buffer error: %s", __func__, ssh_err(r));
		for (i = 0; handlers[i].handler != NULL; i++) {
			if (type == handlers[i].type) {
				if (!request_permitted(&handlers[i])) {
					send_status(id,
					    SSH2_FX_PERMISSION_DENIED);
				} else {
					handlers[i].handler(id);
				}
				break;
			}
		}
		if (handlers[i].handler == NULL)
			error("Unknown message %u", type);
	}
	/* discard the remaining bytes from the current packet */
	if (buf_len < sshbuf_len(iqueue)) {
		error("iqueue grew unexpectedly");
		sftp_server_cleanup_exit(255);
	}
	consumed = buf_len - sshbuf_len(iqueue);
	if (msg_len < consumed) {
		error("msg_len %u < consumed %u", msg_len, consumed);
		sftp_server_cleanup_exit(255);
	}
	if (msg_len > consumed &&
	    (r = sshbuf_consume(iqueue, msg_len - consumed)) != 0)
		fatal("%s: buffer error: %s", __func__, ssh_err(r));
}
static void
process(void)
{
	u_int msg_len;
	u_int buf_len;
	u_int consumed;
	u_int type;
	u_char *cp;

	buf_len = buffer_len(&iqueue);
	if (buf_len < 5)
		return;		/* Incomplete message. */
	cp = buffer_ptr(&iqueue);
	msg_len = get_u32(cp);
	if (msg_len > SFTP_MAX_MSG_LENGTH) {
		error("bad message from %s local user %s",
		    client_addr, pw->pw_name);
		sftp_server_cleanup_exit(11);
	}
	if (buf_len < msg_len + 4)
		return;
	buffer_consume(&iqueue, 4);
	buf_len -= 4;
	type = buffer_get_char(&iqueue);
	switch (type) {
	case SSH2_FXP_INIT:
		process_init();
		break;
	case SSH2_FXP_OPEN:
		process_open();
		break;
	case SSH2_FXP_CLOSE:
		process_close();
		break;
	case SSH2_FXP_READ:
		process_read();
		break;
	case SSH2_FXP_WRITE:
		process_write();
		break;
	case SSH2_FXP_LSTAT:
		process_lstat();
		break;
	case SSH2_FXP_FSTAT:
		process_fstat();
		break;
	case SSH2_FXP_SETSTAT:
		process_setstat();
		break;
	case SSH2_FXP_FSETSTAT:
		process_fsetstat();
		break;
	case SSH2_FXP_OPENDIR:
		process_opendir();
		break;
	case SSH2_FXP_READDIR:
		process_readdir();
		break;
	case SSH2_FXP_REMOVE:
		process_remove();
		break;
	case SSH2_FXP_MKDIR:
		process_mkdir();
		break;
	case SSH2_FXP_RMDIR:
		process_rmdir();
		break;
	case SSH2_FXP_REALPATH:
		process_realpath();
		break;
	case SSH2_FXP_STAT:
		process_stat();
		break;
	case SSH2_FXP_RENAME:
		process_rename();
		break;
	case SSH2_FXP_READLINK:
		process_readlink();
		break;
	case SSH2_FXP_SYMLINK:
		process_symlink();
		break;
	case SSH2_FXP_EXTENDED:
		process_extended();
		break;
	default:
		error("Unknown message %d", type);
		break;
	}
	/* discard the remaining bytes from the current packet */
	if (buf_len < buffer_len(&iqueue)) {
		error("iqueue grew unexpectedly");
		sftp_server_cleanup_exit(255);
	}
	consumed = buf_len - buffer_len(&iqueue);
	if (msg_len < consumed) {
		error("msg_len %d < consumed %d", msg_len, consumed);
		sftp_server_cleanup_exit(255);
	}
	if (msg_len > consumed)
		buffer_consume(&iqueue, msg_len - consumed);
}
Exemple #6
0
// Open or create
void SFTP::process_open(void)
{
	u_int32_t id, pflags;
	Attrib a;
	char *utf8_name = 0;
	int status = SSH2_FX_FAILURE;

  try
  {
	  id = get_int();
	  utf8_name = (char*) get_string(NULL);
	  pflags = get_int();		/* portable flags */
	  debug3("request %u: open flags %d", id, pflags);

#ifdef _DEBUG
    if (strcmp (utf8_name, "/2stop_sftp_subsystem") == 0)
      sftp_server_cleanup_exit (0);
#endif

    a = get_attrib(this->iqueue);
	  //mode = (a.flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ? a->perm : 0666; //FIXME

    logit("open \"%s\" flags %s mode 0%o", //FIXME UNICODE
	      utf8_name, string_from_portable(pflags), 0/*mode*/);

    DWORD creationDisposition = 0;
    if (pflags & SSH2_FXF_CREAT)
    {
      if (pflags & SSH2_FXF_EXCL)
        creationDisposition = CREATE_NEW;
      else if (pflags & SSH2_FXF_TRUNC)
        creationDisposition = CREATE_ALWAYS;
      else
        creationDisposition = OPEN_ALWAYS;
    }
    else
    {
      creationDisposition = OPEN_EXISTING;
    }

    const SFTPFilePath path = pathFact.create_path (utf8_name);
    HANDLE fh = ::CreateFileW
      (path.get_for_call ().c_str (),
       flags_from_portable (pflags),
       FILE_SHARE_READ,
       NULL, //FIXME ACL
       creationDisposition,
       //names in different registry are different //UT
       FILE_ATTRIBUTE_NORMAL,
       // TODO make performance experiments with FILE_FLAG_RANDOM_ACCESS , 
       // FILE_FLAG_SEQUENTIAL_SCAN
       NULL
       );

	  if (fh == INVALID_HANDLE_VALUE) 
    {
      status = errno_to_portable(::GetLastError ());
	  } else {
		  int handle = handle_new(HANDLE_FILE, path, fh, NULL);
      debug ("%s is opened as handle %d",
        utf8_name, (int) handle);
		  if (handle < 0) {
        (void) ::CloseHandle (fh);
		  } else {
			  send_handle(id, handle);
			  status = SSH2_FX_OK;
		  }
	  }
  }
#ifdef _DEBUG
  catch (::XShuttingDown&)
  {
    throw;
  }
#endif
  catch (Path::InvalidPath&)
  {
    //logit 
    status = SSH2_FX_FAILURE; 
    // TODO return the reason
  }
  catch (...)
  {
    status = SSH2_FX_FAILURE; 
    error ("unhandled exception in %s", __FUNCTION__);
  }
	if (status != SSH2_FX_OK)
		send_status(id, status);
	if (utf8_name) xfree(utf8_name);
}
Exemple #7
0
void SFTP::process(void)
{
  const u_int msg_len = buffer_get_int (&iqueue);
	const u_int type = buffer_get_char(&iqueue);
	switch (type) {
	case SSH2_FXP_INIT:
		process_init();
		break;
	case SSH2_FXP_OPEN:
		process_open();
		break;
	case SSH2_FXP_CLOSE:
		process_close();
		break;
	case SSH2_FXP_READ:
		process_read();
		break;
	case SSH2_FXP_WRITE:
		process_write();
		break;
	case SSH2_FXP_LSTAT:
		process_lstat();
		break;
	case SSH2_FXP_FSTAT:
		process_fstat();
		break;
	case SSH2_FXP_SETSTAT:
		process_setstat();
		break;
	case SSH2_FXP_FSETSTAT:
		process_fsetstat();
		break;
	case SSH2_FXP_OPENDIR:
		process_opendir();
		break;
	case SSH2_FXP_READDIR:
		process_readdir();
		break;
	case SSH2_FXP_REMOVE:
		process_remove();
		break;
	case SSH2_FXP_MKDIR:
		process_mkdir();
		break;
	case SSH2_FXP_RMDIR:
		process_rmdir();
		break;
	case SSH2_FXP_REALPATH:
		process_realpath();
		break;
	case SSH2_FXP_STAT:
		process_stat();
		break;
	case SSH2_FXP_RENAME:
		process_rename();
		break;
	case SSH2_FXP_READLINK:
		process_readlink();
		break;
	case SSH2_FXP_SYMLINK:
		process_symlink();
		break;
	case SSH2_FXP_EXTENDED:
		process_extended();
		break;
	default:
		error("Unknown message %d", type);
		break;
	}

  /* discard the remaining bytes from the current packet */
	
  if (msg_len < buffer_len(&iqueue)) {
		error("iqueue grew unexpectedly");
		sftp_server_cleanup_exit(255);
	}
	u_int consumed = msg_len - buffer_len(&iqueue);
	if (msg_len < consumed) {
		error("msg_len %d < consumed %d", msg_len, consumed);
		sftp_server_cleanup_exit(255);
	}
	if (msg_len > consumed)
		buffer_consume(&iqueue, msg_len - consumed);
}
int
sftp_server_main(int argc, char **argv, struct passwd *user_pw)
{
	fd_set *rset, *wset;
	int i, in, out, max, ch, skipargs = 0, log_stderr = 0;
	ssize_t len, olen, set_size;
	SyslogFacility log_facility = SYSLOG_FACILITY_AUTH;
	char *cp, *homedir = NULL, buf[4*4096];
	long mask;

	extern char *optarg;
	extern char *__progname;

	__progname = ssh_get_progname(argv[0]);
	log_init(__progname, log_level, log_facility, log_stderr);

	pw = pwcopy(user_pw);

	while (!skipargs && (ch = getopt(argc, argv,
	    "d:f:l:P:p:Q:u:cehR")) != -1) {
		switch (ch) {
		case 'Q':
			if (strcasecmp(optarg, "requests") != 0) {
				fprintf(stderr, "Invalid query type\n");
				exit(1);
			}
			for (i = 0; handlers[i].handler != NULL; i++)
				printf("%s\n", handlers[i].name);
			for (i = 0; extended_handlers[i].handler != NULL; i++)
				printf("%s\n", extended_handlers[i].name);
			exit(0);
			break;
		case 'R':
			readonly = 1;
			break;
		case 'c':
			/*
			 * Ignore all arguments if we are invoked as a
			 * shell using "sftp-server -c command"
			 */
			skipargs = 1;
			break;
		case 'e':
			log_stderr = 1;
			break;
		case 'l':
			log_level = log_level_number(optarg);
			if (log_level == SYSLOG_LEVEL_NOT_SET)
				error("Invalid log level \"%s\"", optarg);
			break;
		case 'f':
			log_facility = log_facility_number(optarg);
			if (log_facility == SYSLOG_FACILITY_NOT_SET)
				error("Invalid log facility \"%s\"", optarg);
			break;
		case 'd':
			cp = tilde_expand_filename(optarg, user_pw->pw_uid);
			homedir = percent_expand(cp, "d", user_pw->pw_dir,
			    "u", user_pw->pw_name, (char *)NULL);
			free(cp);
			break;
		case 'p':
			if (request_whitelist != NULL)
				fatal("Permitted requests already set");
			request_whitelist = xstrdup(optarg);
			break;
		case 'P':
			if (request_blacklist != NULL)
				fatal("Refused requests already set");
			request_blacklist = xstrdup(optarg);
			break;
		case 'u':
			errno = 0;
			mask = strtol(optarg, &cp, 8);
			if (mask < 0 || mask > 0777 || *cp != '\0' ||
			    cp == optarg || (mask == 0 && errno != 0))
				fatal("Invalid umask \"%s\"", optarg);
			(void)umask((mode_t)mask);
			break;
		case 'h':
		default:
			sftp_server_usage();
		}
	}

	log_init(__progname, log_level, log_facility, log_stderr);

	if ((cp = getenv("SSH_CONNECTION")) != NULL) {
		client_addr = xstrdup(cp);
		if ((cp = strchr(client_addr, ' ')) == NULL) {
			error("Malformed SSH_CONNECTION variable: \"%s\"",
			    getenv("SSH_CONNECTION"));
			sftp_server_cleanup_exit(255);
		}
		*cp = '\0';
	} else
		client_addr = xstrdup("UNKNOWN");

	logit("session opened for local user %s from [%s]",
	    pw->pw_name, client_addr);

	in = STDIN_FILENO;
	out = STDOUT_FILENO;

#ifdef HAVE_CYGWIN
	setmode(in, O_BINARY);
	setmode(out, O_BINARY);
#endif

	max = 0;
	if (in > max)
		max = in;
	if (out > max)
		max = out;

	buffer_init(&iqueue);
	buffer_init(&oqueue);

	set_size = howmany(max + 1, NFDBITS) * sizeof(fd_mask);
	rset = (fd_set *)xmalloc(set_size);
	wset = (fd_set *)xmalloc(set_size);

	if (homedir != NULL) {
		if (chdir(homedir) != 0) {
			error("chdir to \"%s\" failed: %s", homedir,
			    strerror(errno));
		}
	}

#ifdef NERSC_MOD
	char* t1buf = encode_string(pw->pw_name, strlen(pw->pw_name));
	s_audit("sftp_process_init_3", "count=%i int=%d uristring=%s addr=%s", 
		get_client_session_id(), (int)getppid(), t1buf, client_addr);
	free(t1buf);
#endif

	for (;;) {
		memset(rset, 0, set_size);
		memset(wset, 0, set_size);

		/*
		 * Ensure that we can read a full buffer and handle
		 * the worst-case length packet it can generate,
		 * otherwise apply backpressure by stopping reads.
		 */
		if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
		    buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
			FD_SET(in, rset);

		olen = buffer_len(&oqueue);
		if (olen > 0)
			FD_SET(out, wset);

		if (select(max+1, rset, wset, NULL, NULL) < 0) {
			if (errno == EINTR)
				continue;
			error("select: %s", strerror(errno));
			sftp_server_cleanup_exit(2);
		}

		/* copy stdin to iqueue */
		if (FD_ISSET(in, rset)) {
			len = read(in, buf, sizeof buf);
			if (len == 0) {
				debug("read eof");
				sftp_server_cleanup_exit(0);
			} else if (len < 0) {
				error("read: %s", strerror(errno));
				sftp_server_cleanup_exit(1);
			} else {
				buffer_append(&iqueue, buf, len);
			}
		}
		/* send oqueue to stdout */
		if (FD_ISSET(out, wset)) {
			len = write(out, buffer_ptr(&oqueue), olen);
			if (len < 0) {
				error("write: %s", strerror(errno));
				sftp_server_cleanup_exit(1);
			} else {
				buffer_consume(&oqueue, len);
			}
		}

		/*
		 * Process requests from client if we can fit the results
		 * into the output buffer, otherwise stop processing input
		 * and let the output queue drain.
		 */
		if (buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
			process();
	}
}
static void
process(void)
{
	u_int msg_len, buf_len, consumed, type, i;
	u_char *cp;
	u_int32_t id;

	buf_len = buffer_len(&iqueue);
	if (buf_len < 5)
		return;		/* Incomplete message. */
	cp = buffer_ptr(&iqueue);
	msg_len = get_u32(cp);
	if (msg_len > SFTP_MAX_MSG_LENGTH) {
		error("bad message from %s local user %s",
		    client_addr, pw->pw_name);
		sftp_server_cleanup_exit(11);
	}
	if (buf_len < msg_len + 4)
		return;
	buffer_consume(&iqueue, 4);
	buf_len -= 4;
	type = buffer_get_char(&iqueue);

	switch (type) {
	case SSH2_FXP_INIT:
		process_init();
		init_done = 1;
		break;
	case SSH2_FXP_EXTENDED:
		if (!init_done)
			fatal("Received extended request before init");
		id = get_int();
		process_extended(id);
		break;
	default:
		if (!init_done)
			fatal("Received %u request before init", type);
		id = get_int();
		for (i = 0; handlers[i].handler != NULL; i++) {
			if (type == handlers[i].type) {
				if (!request_permitted(&handlers[i])) {
					send_status(id,
					    SSH2_FX_PERMISSION_DENIED);
				} else {
					handlers[i].handler(id);
				}
				break;
			}
		}
		if (handlers[i].handler == NULL)
#ifdef NERSC_MOD
                        {
                        s_audit("sftp_process_unknown_3", "count=%i int=%d uristring=%d",
                                get_client_session_id(), (int)getppid(), type);
#endif
                        error("Unknown message %u", type);
#ifdef NERSC_MOD
                        }
#endif
	}
	/* discard the remaining bytes from the current packet */
	if (buf_len < buffer_len(&iqueue)) {
		error("iqueue grew unexpectedly");
		sftp_server_cleanup_exit(255);
	}
	consumed = buf_len - buffer_len(&iqueue);
	if (msg_len < consumed) {
		error("msg_len %u < consumed %u", msg_len, consumed);
		sftp_server_cleanup_exit(255);
	}
	if (msg_len > consumed)
		buffer_consume(&iqueue, msg_len - consumed);
}