2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Code to connect to a remote host, and to perform the client side of the
6 * login (authentication) dialog.
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
16 RCSID("$OpenBSD: sshconnect.c,v 1.115 2001/10/08 19:05:05 markus Exp $");
18 #include <openssl/bn.h>
28 #include "sshconnect.h"
35 char *client_version_string = NULL;
36 char *server_version_string = NULL;
38 extern Options options;
39 extern char *__progname;
41 #ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
42 #define INET6_ADDRSTRLEN 46
46 sockaddr_ntop(struct sockaddr *sa)
49 static char addrbuf[INET6_ADDRSTRLEN];
51 switch (sa->sa_family) {
53 addr = &((struct sockaddr_in *)sa)->sin_addr;
56 addr = &((struct sockaddr_in6 *)sa)->sin6_addr;
59 /* This case should be protected against elsewhere */
62 inet_ntop(sa->sa_family, addr, addrbuf, sizeof(addrbuf));
67 * Connect to the given ssh server using a proxy command.
70 ssh_proxy_connect(const char *host, u_short port, struct passwd *pw,
71 const char *proxy_command)
78 char strport[NI_MAXSERV];
80 /* Convert the port number into a string. */
81 snprintf(strport, sizeof strport, "%hu", port);
83 /* Build the final command string in the buffer by making the
84 appropriate substitutions to the given proxy command. */
85 buffer_init(&command);
86 for (cp = proxy_command; *cp; cp++) {
87 if (cp[0] == '%' && cp[1] == '%') {
88 buffer_append(&command, "%", 1);
92 if (cp[0] == '%' && cp[1] == 'h') {
93 buffer_append(&command, host, strlen(host));
97 if (cp[0] == '%' && cp[1] == 'p') {
98 buffer_append(&command, strport, strlen(strport));
102 buffer_append(&command, cp, 1);
104 buffer_append(&command, "\0", 1);
106 /* Get the final command string. */
107 command_string = buffer_ptr(&command);
109 /* Create pipes for communicating with the proxy. */
110 if (pipe(pin) < 0 || pipe(pout) < 0)
111 fatal("Could not create pipes to communicate with the proxy: %.100s",
114 debug("Executing proxy command: %.500s", command_string);
116 /* Fork and execute the proxy command. */
117 if ((pid = fork()) == 0) {
120 /* Child. Permanently give up superuser privileges. */
121 permanently_set_uid(pw);
123 /* Redirect stdin and stdout. */
126 if (dup2(pin[0], 0) < 0)
127 perror("dup2 stdin");
131 if (dup2(pout[1], 1) < 0)
132 perror("dup2 stdout");
133 /* Cannot be 1 because pin allocated two descriptors. */
136 /* Stderr is left as it is so that error messages get
137 printed on the user's terminal. */
138 argv[0] = _PATH_BSHELL;
140 argv[2] = command_string;
143 /* Execute the proxy command. Note that we gave up any
144 extra privileges above. */
145 execv(argv[0], argv);
151 fatal("fork failed: %.100s", strerror(errno));
153 /* Close child side of the descriptors. */
157 /* Free the command name. */
158 buffer_free(&command);
160 /* Set the connection file descriptors. */
161 packet_set_connection(pout[0], pin[1]);
163 /* Indicate OK return */
168 * Creates a (possibly privileged) socket for use as the ssh connection.
171 ssh_create_socket(struct passwd *pw, int privileged, int family)
174 struct addrinfo hints, *res;
177 * If we are running as root and want to connect to a privileged
178 * port, bind our own socket to a privileged port.
181 int p = IPPORT_RESERVED - 1;
182 sock = rresvport_af(&p, family);
184 error("rresvport: af=%d %.100s", family, strerror(errno));
186 debug("Allocated local port %d.", p);
190 * Just create an ordinary socket on arbitrary port. We use
191 * the user's uid to create the socket.
193 temporarily_use_uid(pw);
194 sock = socket(family, SOCK_STREAM, 0);
196 error("socket: %.100s", strerror(errno));
199 /* Bind the socket to an alternative local IP address */
200 if (options.bind_address == NULL)
203 memset(&hints, 0, sizeof(hints));
204 hints.ai_family = family;
205 hints.ai_socktype = SOCK_STREAM;
206 hints.ai_flags = AI_PASSIVE;
207 gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
209 error("getaddrinfo: %s: %s", options.bind_address,
210 gai_strerror(gaierr));
214 if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
215 error("bind: %s: %s", options.bind_address, strerror(errno));
225 * Opens a TCP/IP connection to the remote server on the given host.
226 * The address of the remote host will be returned in hostaddr.
227 * If port is 0, the default port will be used. If anonymous is zero,
228 * a privileged port will be allocated to make the connection.
229 * This requires super-user privileges if anonymous is false.
230 * Connection_attempts specifies the maximum number of tries (one per
231 * second). If proxy_command is non-NULL, it specifies the command (with %h
232 * and %p substituted for host and port, respectively) to use to contact
236 * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
237 * ECONNABORTED if we failed without a "Connection refused"
238 * Suitable error messages for the connection failure will already have been
242 ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
243 u_short port, int family, int connection_attempts,
244 int anonymous, struct passwd *pw, const char *proxy_command)
248 int sock = -1, attempt;
249 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
250 struct addrinfo hints, *ai, *aitop;
251 struct linger linger;
254 * Did we get only other errors than "Connection refused" (which
255 * should block fallback to rsh and similar), or did we get at least
256 * one "Connection refused"?
258 int full_failure = 1;
260 debug("ssh_connect: getuid %u geteuid %u anon %d",
261 (u_int) getuid(), (u_int) geteuid(), anonymous);
263 /* Get default port if port has not been set. */
265 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
267 port = ntohs(sp->s_port);
269 port = SSH_DEFAULT_PORT;
271 /* If a proxy command is given, connect using it. */
272 if (proxy_command != NULL)
273 return ssh_proxy_connect(host, port, pw, proxy_command);
275 /* No proxy command. */
277 memset(&hints, 0, sizeof(hints));
278 hints.ai_family = family;
279 hints.ai_socktype = SOCK_STREAM;
280 snprintf(strport, sizeof strport, "%d", port);
281 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
282 fatal("%s: %.100s: %s", __progname, host,
283 gai_strerror(gaierr));
286 * Try to connect several times. On some machines, the first time
287 * will sometimes fail. In general socket code appears to behave
288 * quite magically on many machines.
290 for (attempt = 0; ;) {
292 debug("Trying again...");
294 /* Loop through addresses for this host, and try each one in
295 sequence until the connection succeeds. */
296 for (ai = aitop; ai; ai = ai->ai_next) {
297 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
299 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
300 ntop, sizeof(ntop), strport, sizeof(strport),
301 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
302 error("ssh_connect: getnameinfo failed");
305 debug("Connecting to %.200s [%.100s] port %s.",
306 host, ntop, strport);
308 /* Create a socket for connecting. */
309 sock = ssh_create_socket(pw,
313 !anonymous && geteuid() == 0,
317 /* Any error is already output */
320 /* Connect to the host. We use the user's uid in the
321 * hope that it will help with tcp_wrappers showing
322 * the remote uid as root.
324 temporarily_use_uid(pw);
325 if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
326 /* Successful connection. */
327 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
331 if (errno == ECONNREFUSED)
333 log("ssh: connect to address %s port %s: %s",
334 sockaddr_ntop(ai->ai_addr), strport,
338 * Close the failed socket; there appear to
339 * be some problems when reusing a socket for
340 * which connect() has already returned an
343 shutdown(sock, SHUT_RDWR);
348 break; /* Successful connection. */
351 if (attempt >= connection_attempts)
353 /* Sleep a moment before retrying. */
359 /* Return failure if we didn't get a successful connection. */
360 if (attempt >= connection_attempts)
361 return full_failure ? ECONNABORTED : ECONNREFUSED;
363 debug("Connection established.");
366 * Set socket options. We would like the socket to disappear as soon
367 * as it has been closed for whatever reason.
369 /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
372 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
374 /* Set keepalives if requested. */
375 if (options.keepalives &&
376 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
378 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
380 /* Set the connection. */
381 packet_set_connection(sock, sock);
387 * Waits for the server identification string, and sends our own
388 * identification string.
391 ssh_exchange_identification(void)
393 char buf[256], remote_version[256]; /* must be same size! */
394 int remote_major, remote_minor, i, mismatch;
395 int connection_in = packet_get_connection_in();
396 int connection_out = packet_get_connection_out();
397 int minor1 = PROTOCOL_MINOR_1;
399 /* Read other side\'s version identification. */
401 for (i = 0; i < sizeof(buf) - 1; i++) {
402 int len = atomicio(read, connection_in, &buf[i], 1);
404 fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
406 fatal("ssh_exchange_identification: Connection closed by remote host");
407 if (buf[i] == '\r') {
410 continue; /**XXX wait for \n */
412 if (buf[i] == '\n') {
417 buf[sizeof(buf) - 1] = 0;
418 if (strncmp(buf, "SSH-", 4) == 0)
420 debug("ssh_exchange_identification: %s", buf);
422 server_version_string = xstrdup(buf);
425 * Check that the versions match. In future this might accept
426 * several versions and set appropriate flags to handle them.
428 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
429 &remote_major, &remote_minor, remote_version) != 3)
430 fatal("Bad remote protocol version identification: '%.100s'", buf);
431 debug("Remote protocol version %d.%d, remote software version %.100s",
432 remote_major, remote_minor, remote_version);
434 compat_datafellows(remote_version);
437 switch(remote_major) {
439 if (remote_minor == 99 &&
440 (options.protocol & SSH_PROTO_2) &&
441 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
445 if (!(options.protocol & SSH_PROTO_1)) {
449 if (remote_minor < 3) {
450 fatal("Remote machine has too old SSH software version.");
451 } else if (remote_minor == 3 || remote_minor == 4) {
452 /* We speak 1.3, too. */
455 if (options.forward_agent) {
456 log("Agent forwarding disabled for protocol 1.3");
457 options.forward_agent = 0;
462 if (options.protocol & SSH_PROTO_2) {
472 fatal("Protocol major versions differ: %d vs. %d",
473 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
475 /* Send our own protocol version identification. */
476 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
477 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
478 compat20 ? PROTOCOL_MINOR_2 : minor1,
480 if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
481 fatal("write: %.100s", strerror(errno));
482 client_version_string = xstrdup(buf);
483 chop(client_version_string);
484 chop(server_version_string);
485 debug("Local version string %.100s", client_version_string);
488 /* defaults to 'no' */
490 confirm(const char *prompt)
496 if (options.batch_mode)
498 if (isatty(STDIN_FILENO))
501 f = fopen(_PATH_TTY, "rw");
505 fprintf(stderr, "%s", prompt);
507 if (fgets(buf, sizeof(buf), f) == NULL) {
508 fprintf(stderr, "\n");
509 strlcpy(buf, "no", sizeof buf);
511 /* Remove newline from response. */
512 if (strchr(buf, '\n'))
513 *strchr(buf, '\n') = 0;
514 if (strcmp(buf, "yes") == 0)
516 else if (strcmp(buf, "no") == 0)
519 fprintf(stderr, "Please type 'yes' or 'no': ");
530 * check whether the supplied host key is valid, return -1 if the key
531 * is not valid. the user_hostfile will not be updated if 'readonly' is true.
535 check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
536 int readonly, const char *user_hostfile, const char *system_hostfile)
539 char *type = key_type(host_key);
541 char hostline[1000], *hostp, *fp;
542 HostStatus host_status;
543 HostStatus ip_status;
544 int local = 0, host_ip_differ = 0;
546 char ntop[NI_MAXHOST];
547 int host_line, ip_line;
548 const char *host_file = NULL, *ip_file = NULL;
551 * Force accepting of the host key for loopback/localhost. The
552 * problem is that if the home directory is NFS-mounted to multiple
553 * machines, localhost will refer to a different machine in each of
554 * them, and the user will get bogus HOST_CHANGED warnings. This
555 * essentially disables host authentication for localhost; however,
556 * this is probably not a real problem.
558 /** hostaddr == 0! */
559 switch (hostaddr->sa_family) {
561 local = (ntohl(((struct sockaddr_in *)hostaddr)->
562 sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
563 salen = sizeof(struct sockaddr_in);
566 local = IN6_IS_ADDR_LOOPBACK(
567 &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
568 salen = sizeof(struct sockaddr_in6);
572 salen = sizeof(struct sockaddr_storage);
575 if (options.no_host_authentication_for_localhost == 1 && local &&
576 options.host_key_alias == NULL) {
577 debug("Forcing accepting of host key for "
578 "loopback/localhost.");
583 * We don't have the remote ip-address for connections
584 * using a proxy command
586 if (options.proxy_command == NULL) {
587 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
588 NULL, 0, NI_NUMERICHOST) != 0)
589 fatal("check_host_key: getnameinfo failed");
592 ip = xstrdup("<no hostip for proxy command>");
595 * Turn off check_host_ip if the connection is to localhost, via proxy
596 * command or if we don't have a hostname to compare with
598 if (options.check_host_ip &&
599 (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
600 options.check_host_ip = 0;
603 * Allow the user to record the key under a different name. This is
604 * useful for ssh tunneling over forwarded connections or if you run
605 * multiple sshd's on different ports on the same machine.
607 if (options.host_key_alias != NULL) {
608 host = options.host_key_alias;
609 debug("using hostkeyalias: %s", host);
613 * Store the host key from the known host file in here so that we can
614 * compare it with the key for the IP address.
616 file_key = key_new(host_key->type);
619 * Check if the host key is present in the user\'s list of known
620 * hosts or in the systemwide list.
622 host_file = user_hostfile;
623 host_status = check_host_in_hostfile(host_file, host, host_key,
624 file_key, &host_line);
625 if (host_status == HOST_NEW) {
626 host_file = system_hostfile;
627 host_status = check_host_in_hostfile(host_file, host, host_key,
628 file_key, &host_line);
631 * Also perform check for the ip address, skip the check if we are
632 * localhost or the hostname was an ip address to begin with
634 if (options.check_host_ip) {
635 Key *ip_key = key_new(host_key->type);
637 ip_file = user_hostfile;
638 ip_status = check_host_in_hostfile(ip_file, ip, host_key,
640 if (ip_status == HOST_NEW) {
641 ip_file = system_hostfile;
642 ip_status = check_host_in_hostfile(ip_file, ip,
643 host_key, ip_key, &ip_line);
645 if (host_status == HOST_CHANGED &&
646 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
651 ip_status = host_status;
655 switch (host_status) {
657 /* The host is known and the key matches. */
658 debug("Host '%.200s' is known and matches the %s host key.",
660 debug("Found key in %s:%d", host_file, host_line);
661 if (options.check_host_ip && ip_status == HOST_NEW) {
663 log("%s host key for IP address "
664 "'%.128s' not in list of known hosts.",
666 else if (!add_host_to_hostfile(user_hostfile, ip,
668 log("Failed to add the %s host key for IP "
669 "address '%.128s' to the list of known "
670 "hosts (%.30s).", type, ip, user_hostfile);
672 log("Warning: Permanently added the %s host "
673 "key for IP address '%.128s' to the list "
674 "of known hosts.", type, ip);
680 /* The host is new. */
681 if (options.strict_host_key_checking == 1) {
683 * User has requested strict host key checking. We
684 * will not add the host key automatically. The only
685 * alternative left is to abort.
687 error("No %s host key is known for %.200s and you "
688 "have requested strict checking.", type, host);
690 } else if (options.strict_host_key_checking == 2) {
693 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
694 snprintf(prompt, sizeof(prompt),
695 "The authenticity of host '%.200s (%s)' can't be "
697 "%s key fingerprint is %s.\n"
698 "Are you sure you want to continue connecting "
699 "(yes/no)? ", host, ip, type, fp);
701 if (!confirm(prompt)) {
705 if (options.check_host_ip && ip_status == HOST_NEW) {
706 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
712 * If not in strict mode, add the key automatically to the
713 * local known_hosts file.
715 if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
716 log("Failed to add the host to the list of known "
717 "hosts (%.500s).", user_hostfile);
719 log("Warning: Permanently added '%.200s' (%s) to the "
720 "list of known hosts.", hostp, type);
723 if (options.check_host_ip && host_ip_differ) {
725 if (ip_status == HOST_NEW)
727 else if (ip_status == HOST_OK)
728 msg = "is unchanged";
730 msg = "has a different value";
731 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
732 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
733 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
734 error("The %s host key for %s has changed,", type, host);
735 error("and the key for the according IP address %s", ip);
736 error("%s. This could either mean that", msg);
737 error("DNS SPOOFING is happening or the IP address for the host");
738 error("and its host key have changed at the same time.");
739 if (ip_status != HOST_NEW)
740 error("Offending key for IP in %s:%d", ip_file, ip_line);
742 /* The host key has changed. */
743 fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
744 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
745 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
746 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
747 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
748 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
749 error("It is also possible that the %s host key has just been changed.", type);
750 error("The fingerprint for the %s key sent by the remote host is\n%s.",
752 error("Please contact your system administrator.");
753 error("Add correct host key in %.100s to get rid of this message.",
755 error("Offending key in %s:%d", host_file, host_line);
759 * If strict host key checking is in use, the user will have
760 * to edit the key manually and we can only abort.
762 if (options.strict_host_key_checking) {
763 error("%s host key for %.200s has changed and you have "
764 "requested strict checking.", type, host);
769 * If strict host key checking has not been requested, allow
770 * the connection but without password authentication or
773 if (options.password_authentication) {
774 error("Password authentication is disabled to avoid "
775 "man-in-the-middle attacks.");
776 options.password_authentication = 0;
778 if (options.forward_agent) {
779 error("Agent forwarding is disabled to avoid "
780 "man-in-the-middle attacks.");
781 options.forward_agent = 0;
783 if (options.forward_x11) {
784 error("X11 forwarding is disabled to avoid "
785 "man-in-the-middle attacks.");
786 options.forward_x11 = 0;
788 if (options.num_local_forwards > 0 ||
789 options.num_remote_forwards > 0) {
790 error("Port forwarding is disabled to avoid "
791 "man-in-the-middle attacks.");
792 options.num_local_forwards =
793 options.num_remote_forwards = 0;
796 * XXX Should permit the user to change to use the new id.
797 * This could be done by converting the host key to an
798 * identifying sentence, tell that the host identifies itself
799 * by that sentence, and ask the user if he/she whishes to
800 * accept the authentication.
805 if (options.check_host_ip && host_status != HOST_CHANGED &&
806 ip_status == HOST_CHANGED) {
807 log("Warning: the %s host key for '%.200s' "
808 "differs from the key for the IP address '%.128s'",
810 if (host_status == HOST_OK)
811 log("Matching host key in %s:%d", host_file, host_line);
812 log("Offending key for IP in %s:%d", ip_file, ip_line);
813 if (options.strict_host_key_checking == 1) {
814 error("Exiting, you have requested strict checking.");
816 } else if (options.strict_host_key_checking == 2) {
817 if (!confirm("Are you sure you want "
818 "to continue connecting (yes/no)? ")) {
833 verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
837 /* return ok if the key can be found in an old keyfile */
838 if (stat(options.system_hostfile2, &st) == 0 ||
839 stat(options.user_hostfile2, &st) == 0) {
840 if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
841 options.user_hostfile2, options.system_hostfile2) == 0)
844 return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
845 options.user_hostfile, options.system_hostfile);
849 * Starts a dialog with the server, and authenticates the current user on the
850 * server. This does not need any extra privileges. The basic connection
851 * to the server must already have been established before this is called.
852 * If login fails, this function prints an error and never returns.
853 * This function does not require super-user privileges.
856 ssh_login(Key **keys, int nkeys, const char *orighost,
857 struct sockaddr *hostaddr, struct passwd *pw)
860 char *server_user, *local_user;
862 local_user = xstrdup(pw->pw_name);
863 server_user = options.user ? options.user : local_user;
865 /* Convert the user-supplied hostname into all lowercase. */
866 host = xstrdup(orighost);
867 for (cp = host; *cp; cp++)
871 /* Exchange protocol version identification strings with the server. */
872 ssh_exchange_identification();
874 /* Put the connection into non-blocking mode. */
875 packet_set_nonblocking();
878 /* authenticate user */
880 ssh_kex2(host, hostaddr);
881 ssh_userauth2(local_user, server_user, host, keys, nkeys);
883 ssh_kex(host, hostaddr);
884 ssh_userauth1(local_user, server_user, host, keys, nkeys);
889 ssh_put_password(char *password)
894 if (datafellows & SSH_BUG_PASSWORDPAD) {
895 packet_put_cstring(password);
898 size = roundup(strlen(password) + 1, 32);
899 padded = xmalloc(size);
900 memset(padded, 0, size);
901 strlcpy(padded, password, size);
902 packet_put_string(padded, size);
903 memset(padded, 0, size);