for (i = 0; i < options.num_identity_files2; i++) options.identity_files2[i] = tilde_expand_filename(options.identity_files2[i], original_real_uid);
main(int ac, char **av){	int i, opt, optind, exit_status, ok;	u_short fwd_port, fwd_host_port;	char *optarg, *cp, buf[256];	struct stat st;	struct passwd *pw, pwcopy;	int dummy;	uid_t original_effective_uid;	/*	 * Save the original real uid.  It will be needed later (uid-swapping	 * may clobber the real uid).	 */	original_real_uid = getuid();	original_effective_uid = geteuid();	/* If we are installed setuid root be careful to not drop core. */	if (original_real_uid != original_effective_uid) {		struct rlimit rlim;		rlim.rlim_cur = rlim.rlim_max = 0;		if (setrlimit(RLIMIT_CORE, &rlim) < 0)			fatal("setrlimit failed: %.100s", strerror(errno));	}	/*	 * Use uid-swapping to give up root privileges for the duration of	 * option processing.  We will re-instantiate the rights when we are	 * ready to create the privileged port, and will permanently drop	 * them when the port has been created (actually, when the connection	 * has been made, as we may need to create the port several times).	 */	temporarily_use_uid(original_real_uid);	/*	 * Set our umask to something reasonable, as some files are created	 * with the default umask.  This will make them world-readable but	 * writable only by the owner, which is ok for all files for which we	 * don't set the modes explicitly.	 */	umask(022);	/* Save our own name. */	av0 = av[0];	/* Initialize option structure to indicate that no values have been set. */	initialize_options(&options);	/* Parse command-line arguments. */	host = NULL;	/* If program name is not one of the standard names, use it as host name. */	if (strchr(av0, '/'))		cp = strrchr(av0, '/') + 1;	else		cp = av0;	if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 &&	    strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0)		host = cp;	for (optind = 1; optind < ac; optind++) {		if (av[optind][0] != '-') {			if (host)				break;			if ((cp = strchr(av[optind], '@'))) {				if(cp == av[optind])					usage();				options.user = av[optind];				*cp = '\0';				host = ++cp;			} else				host = av[optind];			continue;		}		opt = av[optind][1];		if (!opt)			usage();		if (strchr("eilcpLRo", opt)) {	/* options with arguments */			optarg = av[optind] + 2;			if (strcmp(optarg, "") == 0) {				if (optind >= ac - 1)					usage();				optarg = av[++optind];			}		} else {			if (av[optind][2])				usage();			optarg = NULL;		}		switch (opt) {		case '2':			options.protocol = SSH_PROTO_2;			break;		case '4':			IPv4or6 = AF_INET;			break;		case '6':			IPv4or6 = AF_INET6;			break;		case 'n':			stdin_null_flag = 1;			break;		case 'f':			fork_after_authentication_flag = 1;			stdin_null_flag = 1;			break;		case 'x':			options.forward_x11 = 0;			break;		case 'X':			options.forward_x11 = 1;			break;		case 'g':			options.gateway_ports = 1;			break;		case 'P':			options.use_privileged_port = 0;			break;		case 'a':			options.forward_agent = 0;			break;#ifdef AFS		case 'k':			options.kerberos_tgt_passing = 0;			options.afs_token_passing = 0;			break;#endif		case 'i':			if (stat(optarg, &st) < 0) {				fprintf(stderr, "Warning: Identity file %s does not exist.\n",					optarg);				break;			}			if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)				fatal("Too many identity files specified (max %d)",				      SSH_MAX_IDENTITY_FILES);			options.identity_files[options.num_identity_files++] =				xstrdup(optarg);			break;		case 't':			tty_flag = 1;			break;		case 'v':		case 'V':			fprintf(stderr, "SSH Version %s, protocol versions %d.%d/%d.%d.\n",			    SSH_VERSION,			    PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,			    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);			fprintf(stderr, "Compiled with SSL (0x%8.8lx).\n", SSLeay());			if (opt == 'V')				exit(0);			debug_flag = 1;			options.log_level = SYSLOG_LEVEL_DEBUG;			break;		case 'q':			options.log_level = SYSLOG_LEVEL_QUIET;			break;		case 'e':			if (optarg[0] == '^' && optarg[2] == 0 &&			    (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128)				options.escape_char = (unsigned char) optarg[1] & 31;			else if (strlen(optarg) == 1)				options.escape_char = (unsigned char) optarg[0];			else if (strcmp(optarg, "none") == 0)				options.escape_char = -2;			else {				fprintf(stderr, "Bad escape character '%s'.\n", optarg);				exit(1);			}			break;		case 'c':			options.cipher = cipher_number(optarg);			if (options.cipher == -1) {				fprintf(stderr, "Unknown cipher type '%s'\n", optarg);				exit(1);			}			break;		case 'p':			options.port = atoi(optarg);			break;		case 'l':			options.user = optarg;			break;		case 'R':			if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,			    &fwd_host_port) != 3 &&			    sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,			    &fwd_host_port) != 3) {				fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);				usage();				/* NOTREACHED */			}			add_remote_forward(&options, fwd_port, buf, fwd_host_port);			break;		case 'L':			if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,			    &fwd_host_port) != 3 &&			    sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,			    &fwd_host_port) != 3) {				fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);				usage();				/* NOTREACHED */			}			add_local_forward(&options, fwd_port, buf, fwd_host_port);			break;		case 'C':			options.compression = 1;			break;		case 'N':			no_shell_flag = 1;			no_tty_flag = 1;			break;		case 'T':			no_tty_flag = 1;			break;		case 'o':			dummy = 1;			if (process_config_line(&options, host ? host : "", optarg,					 "command-line", 0, &dummy) != 0)				exit(1);			break;		default:			usage();		}	}	/* Check that we got a host name. */	if (!host)		usage();	/* check if RSA support exists */	if (rsa_alive() == 0) {		extern char *__progname;		fprintf(stderr,			"%s: no RSA support in libssl and libcrypto.  See ssl(8).\n",			__progname);		exit(1);	}	/* Initialize the command to execute on remote host. */	buffer_init(&command);	/*	 * Save the command to execute on the remote host in a buffer. There	 * is no limit on the length of the command, except by the maximum	 * packet size.  Also sets the tty flag if there is no command.	 */	if (optind == ac) {		/* No command specified - execute shell on a tty. */		tty_flag = 1;	} else {		/* A command has been specified.  Store it into the		   buffer. */		for (i = optind; i < ac; i++) {			if (i > optind)				buffer_append(&command, " ", 1);			buffer_append(&command, av[i], strlen(av[i]));		}	}	/* Cannot fork to background if no command. */	if (fork_after_authentication_flag && buffer_len(&command) == 0)		fatal("Cannot fork into background without a command to execute.");	/* Allocate a tty by default if no command specified. */	if (buffer_len(&command) == 0)		tty_flag = 1;	/* Do not allocate a tty if stdin is not a tty. */	if (!isatty(fileno(stdin))) {		if (tty_flag)			fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n");		tty_flag = 0;	}	/* force */	if (no_tty_flag)		tty_flag = 0;	/* Get user data. */	pw = getpwuid(original_real_uid);	if (!pw) {		fprintf(stderr, "You don't exist, go away!\n");		exit(1);	}	/* Take a copy of the returned structure. */	memset(&pwcopy, 0, sizeof(pwcopy));	pwcopy.pw_name = xstrdup(pw->pw_name);	pwcopy.pw_passwd = xstrdup(pw->pw_passwd);	pwcopy.pw_uid = pw->pw_uid;	pwcopy.pw_gid = pw->pw_gid;	pwcopy.pw_dir = xstrdup(pw->pw_dir);	pwcopy.pw_shell = xstrdup(pw->pw_shell);	pw = &pwcopy;	/* Initialize "log" output.  Since we are the client all output	   actually goes to the terminal. */	log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);	/* Read per-user configuration file. */	snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE);	read_config_file(buf, host, &options);	/* Read systemwide configuration file. */	read_config_file(HOST_CONFIG_FILE, host, &options);	/* Fill configuration defaults. */	fill_default_options(&options);	/* reinit */	log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);	if (options.user == NULL)		options.user = xstrdup(pw->pw_name);	if (options.hostname != NULL)		host = options.hostname;	/* Find canonic host name. */	if (strchr(host, '.') == 0) {		struct addrinfo hints;		struct addrinfo *ai = NULL;		int errgai;		memset(&hints, 0, sizeof(hints));		hints.ai_family = IPv4or6;		hints.ai_flags = AI_CANONNAME;		hints.ai_socktype = SOCK_STREAM;		errgai = getaddrinfo(host, NULL, &hints, &ai);		if (errgai == 0) {			if (ai->ai_canonname != NULL)				host = xstrdup(ai->ai_canonname);			freeaddrinfo(ai);		}	}	/* Disable rhosts authentication if not running as root. */	if (original_effective_uid != 0 || !options.use_privileged_port) {		options.rhosts_authentication = 0;		options.rhosts_rsa_authentication = 0;	}	/*	 * If using rsh has been selected, exec it now (without trying	 * anything else).  Note that we must release privileges first.	 */	if (options.use_rsh) {		/*		 * Restore our superuser privileges.  This must be done		 * before permanently setting the uid.		 */		restore_uid();		/* Switch to the original uid permanently. */		permanently_set_uid(original_real_uid);		/* Execute rsh. */		rsh_connect(host, options.user, &command);		fatal("rsh_connect returned");	}	/* Restore our superuser privileges. */	restore_uid();	/*	 * Open a connection to the remote host.  This needs root privileges	 * if rhosts_{rsa_}authentication is enabled.	 */	ok = ssh_connect(host, &hostaddr, options.port,			 options.connection_attempts,			 !options.rhosts_authentication &&			 !options.rhosts_rsa_authentication,			 original_real_uid,			 options.proxy_command);	/*	 * If we successfully made the connection, load the host private key	 * in case we will need it later for combined rsa-rhosts	 * authentication. This must be done before releasing extra	 * privileges, because the file is only readable by root.	 */	if (ok) {		host_private_key = RSA_new();		if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL))			host_private_key_loaded = 1;	}	/*	 * Get rid of any extra privileges that we may have.  We will no	 * longer need them.  Also, extra privileges could make it very hard	 * to read identity files and other non-world-readable files from the	 * user's home directory if it happens to be on a NFS volume where	 * root is mapped to nobody.	 */	/*	 * Note that some legacy systems need to postpone the following call	 * to permanently_set_uid() until the private hostkey is destroyed	 * with RSA_free().  Otherwise the calling user could ptrace() the	 * process, read the private hostkey and impersonate the host.	 * OpenBSD does not allow ptracing of setuid processes.	 */	permanently_set_uid(original_real_uid);	/*	 * Now that we are back to our own permissions, create ~/.ssh	 * directory if it doesn\'t already exist.	 */	snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR);	if (stat(buf, &st) < 0)		if (mkdir(buf, 0755) < 0)			error("Could not create directory '%.200s'.", buf);	/* Check if the connection failed, and try "rsh" if appropriate. */	if (!ok) {		if (options.port != 0)			log("Secure connection to %.100s on port %hu refused%.100s.",			    host, options.port,			    options.fallback_to_rsh ? "; reverting to insecure method" : "");		else			log("Secure connection to %.100s refused%.100s.", host,			    options.fallback_to_rsh ? "; reverting to insecure method" : "");		if (options.fallback_to_rsh) {			rsh_connect(host, options.user, &command);			fatal("rsh_connect returned");		}		exit(1);	}	/* Expand ~ in options.identity_files. */	for (i = 0; i < options.num_identity_files; i++)		options.identity_files[i] =			tilde_expand_filename(options.identity_files[i], original_real_uid);	/* Expand ~ in known host file names. */	options.system_hostfile = tilde_expand_filename(options.system_hostfile,							original_real_uid);	options.user_hostfile = tilde_expand_filename(options.user_hostfile,						      original_real_uid);	/* Log into the remote system.  This never returns if the login fails. */	ssh_login(host_private_key_loaded, host_private_key,		  host, (struct sockaddr *)&hostaddr, original_real_uid);	/* We no longer need the host private key.  Clear it now. */	if (host_private_key_loaded)		RSA_free(host_private_key);	/* Destroys contents safely */	exit_status = compat20 ? ssh_session2() : ssh_session();	packet_close();	return exit_status;}