putty-source/unix/uxplink.c

/*
 * PLink - a command-line (stdin/stdout) variant of PuTTY.
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <assert.h>
#include <stdarg.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <pwd.h>
#include <sys/ioctl.h>

/* More helpful version of the FD_SET macro, to also handle maxfd. */
#define FD_SET_MAX(fd, max, set) do { \
    FD_SET(fd, &set); \
    if (max < fd + 1) max = fd + 1; \
} while (0)

#define PUTTY_DO_GLOBALS	       /* actually _define_ globals */
#include "putty.h"
#include "storage.h"
#include "tree234.h"

#define MAX_STDIN_BACKLOG 4096

void fatalbox(char *p, ...)
{
    va_list ap;
    fprintf(stderr, "FATAL ERROR: ");
    va_start(ap, p);
    vfprintf(stderr, p, ap);
    va_end(ap);
    fputc('\n', stderr);
    cleanup_exit(1);
}
void modalfatalbox(char *p, ...)
{
    va_list ap;
    fprintf(stderr, "FATAL ERROR: ");
    va_start(ap, p);
    vfprintf(stderr, p, ap);
    va_end(ap);
    fputc('\n', stderr);
    cleanup_exit(1);
}
void connection_fatal(void *frontend, char *p, ...)
{
    va_list ap;
    fprintf(stderr, "FATAL ERROR: ");
    va_start(ap, p);
    vfprintf(stderr, p, ap);
    va_end(ap);
    fputc('\n', stderr);
    cleanup_exit(1);
}
void cmdline_error(char *p, ...)
{
    va_list ap;
    fprintf(stderr, "plink: ");
    va_start(ap, p);
    vfprintf(stderr, p, ap);
    va_end(ap);
    fputc('\n', stderr);
    exit(1);
}

struct termios orig_termios;

static Backend *back;
static void *backhandle;

/*
 * Default settings that are specific to pterm.
 */
char *platform_default_s(char *name)
{
    if (!strcmp(name, "X11Display"))
	return getenv("DISPLAY");
    if (!strcmp(name, "TermType"))
	return getenv("TERM");
    if (!strcmp(name, "UserName")) {
	/*
	 * Remote login username will default to the local username.
	 */
	struct passwd *p;
	uid_t uid = getuid();
	char *user, *ret = NULL;

	/*
	 * First, find who we think we are using getlogin. If this
	 * agrees with our uid, we'll go along with it. This should
	 * allow sharing of uids between several login names whilst
	 * coping correctly with people who have su'ed.
	 */
	user = getlogin();
	setpwent();
	if (user)
	    p = getpwnam(user);
	else
	    p = NULL;
	if (p && p->pw_uid == uid) {
	    /*
	     * The result of getlogin() really does correspond to
	     * our uid. Fine.
	     */
	    ret = user;
	} else {
	    /*
	     * If that didn't work, for whatever reason, we'll do
	     * the simpler version: look up our uid in the password
	     * file and map it straight to a name.
	     */
	    p = getpwuid(uid);
	    ret = p->pw_name;
	}
	endpwent();

	return ret;
    }
    return NULL;
}

int platform_default_i(char *name, int def)
{
    if (!strcmp(name, "TermWidth") ||
	!strcmp(name, "TermHeight")) {
	struct winsize size;
	if (ioctl(0, TIOCGWINSZ, (void *)&size) >= 0)
	    return (!strcmp(name, "TermWidth") ? size.ws_col : size.ws_row);
    }
    return def;
}

char *x_get_default(char *key)
{
    return NULL;		       /* this is a stub */
}
int term_ldisc(Terminal *term, int mode)
{
    return FALSE;
}
void ldisc_update(void *frontend, int echo, int edit)
{
    /* Update stdin read mode to reflect changes in line discipline. */
    struct termios mode;

    mode = orig_termios;

    if (echo)
	mode.c_lflag |= ECHO;
    else
	mode.c_lflag &= ~ECHO;

    if (edit)
	mode.c_lflag |= ISIG | ICANON;
    else
	mode.c_lflag &= ~(ISIG | ICANON);

    tcsetattr(0, TCSANOW, &mode);
}

void cleanup_termios(void)
{
    tcsetattr(0, TCSANOW, &orig_termios);
}

bufchain stdout_data, stderr_data;

void try_output(int is_stderr)
{
    bufchain *chain = (is_stderr ? &stderr_data : &stdout_data);
    int fd = (is_stderr ? 2 : 1);
    void *senddata;
    int sendlen, ret;

    if (bufchain_size(chain) == 0)
        return;

    bufchain_prefix(chain, &senddata, &sendlen);
    ret = write(fd, senddata, sendlen);
    if (ret > 0)
	bufchain_consume(chain, ret);
    else if (ret < 0) {
	perror(is_stderr ? "stderr: write" : "stdout: write");
	exit(1);
    }
}

int from_backend(void *frontend_handle, int is_stderr, char *data, int len)
{
    int osize, esize;

    assert(len > 0);

    if (is_stderr) {
	bufchain_add(&stderr_data, data, len);
	try_output(1);
    } else {
	bufchain_add(&stdout_data, data, len);
	try_output(0);
    }

    osize = bufchain_size(&stdout_data);
    esize = bufchain_size(&stderr_data);

    return osize + esize;
}

int signalpipe[2];

void sigwinch(int signum)
{
    write(signalpipe[1], "x", 1);
}

/*
 * Short description of parameters.
 */
static void usage(void)
{
    printf("PuTTY Link: command-line connection utility\n");
    printf("%s\n", ver);
    printf("Usage: plink [options] [user@]host [command]\n");
    printf("       (\"host\" can also be a PuTTY saved session name)\n");
    printf("Options:\n");
    printf("  -v        show verbose messages\n");
    printf("  -load sessname  Load settings from saved session\n");
    printf("  -ssh -telnet -rlogin -raw\n");
    printf("            force use of a particular protocol (default SSH)\n");
    printf("  -P port   connect to specified port\n");
    printf("  -l user   connect with specified username\n");
    printf("  -m file   read remote command(s) from file\n");
    printf("  -batch    disable all interactive prompts\n");
    printf("The following options only apply to SSH connections:\n");
    printf("  -pw passw login with specified password\n");
    printf("  -L listen-port:host:port   Forward local port to "
	   "remote address\n");
    printf("  -R listen-port:host:port   Forward remote port to"
	   " local address\n");
    printf("  -X -x     enable / disable X11 forwarding\n");
    printf("  -A -a     enable / disable agent forwarding\n");
    printf("  -t -T     enable / disable pty allocation\n");
    printf("  -1 -2     force use of particular protocol version\n");
    printf("  -C        enable compression\n");
    printf("  -i key    private key file for authentication\n");
    exit(1);
}

int main(int argc, char **argv)
{
    int sending;
    int portnumber = -1;
    int *sklist;
    int socket;
    int i, skcount, sksize, socketstate;
    int connopen;
    int exitcode;
    int errors;
    void *ldisc;

    ssh_get_line = console_get_line;

    sklist = NULL;
    skcount = sksize = 0;
    /*
     * Initialise port and protocol to sensible defaults. (These
     * will be overridden by more or less anything.)
     */
    default_protocol = PROT_SSH;
    default_port = 22;

    flags = FLAG_STDERR;
    /*
     * Process the command line.
     */
    do_defaults(NULL, &cfg);
    default_protocol = cfg.protocol;
    default_port = cfg.port;
    errors = 0;
    {
	/*
	 * Override the default protocol if PLINK_PROTOCOL is set.
	 */
	char *p = getenv("PLINK_PROTOCOL");
	int i;
	if (p) {
	    for (i = 0; backends[i].backend != NULL; i++) {
		if (!strcmp(backends[i].name, p)) {
		    default_protocol = cfg.protocol = backends[i].protocol;
		    default_port = cfg.port =
			backends[i].backend->default_port;
		    break;
		}
	    }
	}
    }
    while (--argc) {
	char *p = *++argv;
	if (*p == '-') {
	    int ret = cmdline_process_param(p, (argc > 1 ? argv[1] : NULL),
					    1, &cfg);
	    if (ret == -2) {
		fprintf(stderr,
			"plink: option \"%s\" requires an argument\n", p);
		errors = 1;
	    } else if (ret == 2) {
		--argc, ++argv;
	    } else if (ret == 1) {
		continue;
	    } else if (!strcmp(p, "-batch")) {
		console_batch_mode = 1;
	    } else if (!strcmp(p, "-o")) {
                if (argc <= 1) {
                    fprintf(stderr,
                            "plink: option \"-o\" requires an argument\n");
		    errors = 1;
		} else {
                    --argc;
		    provide_xrm_string(*++argv);
		}
	    } else {
		fprintf(stderr, "plink: unknown option \"%s\"\n", p);
		errors = 1;
	    }
	} else if (*p) {
	    if (!*cfg.host) {
		char *q = p;

                do_defaults(NULL, &cfg);

		/*
		 * If the hostname starts with "telnet:", set the
		 * protocol to Telnet and process the string as a
		 * Telnet URL.
		 */
		if (!strncmp(q, "telnet:", 7)) {
		    char c;

		    q += 7;
		    if (q[0] == '/' && q[1] == '/')
			q += 2;
		    cfg.protocol = PROT_TELNET;
		    p = q;
		    while (*p && *p != ':' && *p != '/')
			p++;
		    c = *p;
		    if (*p)
			*p++ = '\0';
		    if (c == ':')
			cfg.port = atoi(p);
		    else
			cfg.port = -1;
		    strncpy(cfg.host, q, sizeof(cfg.host) - 1);
		    cfg.host[sizeof(cfg.host) - 1] = '\0';
		} else {
		    char *r;
		    /*
		     * Before we process the [user@]host string, we
		     * first check for the presence of a protocol
		     * prefix (a protocol name followed by ",").
		     */
		    r = strchr(p, ',');
		    if (r) {
			int i, j;
			for (i = 0; backends[i].backend != NULL; i++) {
			    j = strlen(backends[i].name);
			    if (j == r - p &&
				!memcmp(backends[i].name, p, j)) {
				default_protocol = cfg.protocol =
				    backends[i].protocol;
				portnumber =
				    backends[i].backend->default_port;
				p = r + 1;
				break;
			    }
			}
		    }

		    /*
		     * Three cases. Either (a) there's a nonzero
		     * length string followed by an @, in which
		     * case that's user and the remainder is host.
		     * Or (b) there's only one string, not counting
		     * a potential initial @, and it exists in the
		     * saved-sessions database. Or (c) only one
		     * string and it _doesn't_ exist in the
		     * database.
		     */
		    r = strrchr(p, '@');
		    if (r == p)
			p++, r = NULL; /* discount initial @ */
		    if (r == NULL) {
			/*
			 * One string.
			 */
			Config cfg2;
			do_defaults(p, &cfg2);
			if (cfg2.host[0] == '\0') {
			    /* No settings for this host; use defaults */
			    strncpy(cfg.host, p, sizeof(cfg.host) - 1);
			    cfg.host[sizeof(cfg.host) - 1] = '\0';
			    cfg.port = default_port;
			} else {
			    cfg = cfg2;
			    cfg.remote_cmd_ptr = cfg.remote_cmd;
			}
		    } else {
			*r++ = '\0';
			strncpy(cfg.username, p, sizeof(cfg.username) - 1);
			cfg.username[sizeof(cfg.username) - 1] = '\0';
			strncpy(cfg.host, r, sizeof(cfg.host) - 1);
			cfg.host[sizeof(cfg.host) - 1] = '\0';
			cfg.port = default_port;
		    }
		}
	    } else {
		char *command;
		int cmdlen, cmdsize;
		cmdlen = cmdsize = 0;
		command = NULL;

		while (argc) {
		    while (*p) {
			if (cmdlen >= cmdsize) {
			    cmdsize = cmdlen + 512;
			    command = srealloc(command, cmdsize);
			}
			command[cmdlen++]=*p++;
		    }
		    if (cmdlen >= cmdsize) {
			cmdsize = cmdlen + 512;
			command = srealloc(command, cmdsize);
		    }
		    command[cmdlen++]=' '; /* always add trailing space */
		    if (--argc) p = *++argv;
		}
		if (cmdlen) command[--cmdlen]='\0';
				       /* change trailing blank to NUL */
		cfg.remote_cmd_ptr = command;
		cfg.remote_cmd_ptr2 = NULL;
		cfg.nopty = TRUE;      /* command => no terminal */

		break;		       /* done with cmdline */
	    }
	}
    }

    if (errors)
	return 1;

    if (!*cfg.host) {
	usage();
    }

    /*
     * Trim leading whitespace off the hostname if it's there.
     */
    {
	int space = strspn(cfg.host, " \t");
	memmove(cfg.host, cfg.host+space, 1+strlen(cfg.host)-space);
    }

    /* See if host is of the form user@host */
    if (cfg.host[0] != '\0') {
	char *atsign = strchr(cfg.host, '@');
	/* Make sure we're not overflowing the user field */
	if (atsign) {
	    if (atsign - cfg.host < sizeof cfg.username) {
		strncpy(cfg.username, cfg.host, atsign - cfg.host);
		cfg.username[atsign - cfg.host] = '\0';
	    }
	    memmove(cfg.host, atsign + 1, 1 + strlen(atsign + 1));
	}
    }

    /*
     * Perform command-line overrides on session configuration.
     */
    cmdline_run_saved(&cfg);

    /*
     * Trim a colon suffix off the hostname if it's there.
     */
    cfg.host[strcspn(cfg.host, ":")] = '\0';

    /*
     * Remove any remaining whitespace from the hostname.
     */
    {
	int p1 = 0, p2 = 0;
	while (cfg.host[p2] != '\0') {
	    if (cfg.host[p2] != ' ' && cfg.host[p2] != '\t') {
		cfg.host[p1] = cfg.host[p2];
		p1++;
	    }
	    p2++;
	}
	cfg.host[p1] = '\0';
    }

    if (!*cfg.remote_cmd_ptr)
	flags |= FLAG_INTERACTIVE;

    /*
     * Select protocol. This is farmed out into a table in a
     * separate file to enable an ssh-free variant.
     */
    {
	int i;
	back = NULL;
	for (i = 0; backends[i].backend != NULL; i++)
	    if (backends[i].protocol == cfg.protocol) {
		back = backends[i].backend;
		break;
	    }
	if (back == NULL) {
	    fprintf(stderr,
		    "Internal fault: Unsupported protocol found\n");
	    return 1;
	}
    }

    /*
     * Select port.
     */
    if (portnumber != -1)
	cfg.port = portnumber;

    /*
     * Set up the pipe we'll use to tell us about SIGWINCH.
     */
    if (pipe(signalpipe) < 0) {
	perror("pipe");
	exit(1);
    }
    putty_signal(SIGWINCH, sigwinch);

    sk_init();

    /*
     * Start up the connection.
     */
    logctx = log_init(NULL);
    {
	char *error;
	char *realhost;
	/* nodelay is only useful if stdin is a terminal device */
	int nodelay = cfg.tcp_nodelay && isatty(0);

	error = back->init(NULL, &backhandle, &cfg, cfg.host, cfg.port,
			   &realhost, nodelay);
	if (error) {
	    fprintf(stderr, "Unable to open connection:\n%s\n", error);
	    return 1;
	}
	back->provide_logctx(backhandle, logctx);
	ldisc = ldisc_create(&cfg, NULL, back, backhandle, NULL);
	sfree(realhost);
    }
    connopen = 1;

    /*
     * Set up the initial console mode. We don't care if this call
     * fails, because we know we aren't necessarily running in a
     * console.
     */
    tcgetattr(0, &orig_termios);
    atexit(cleanup_termios);
    ldisc_update(NULL, 1, 1);
    sending = FALSE;

    while (1) {
	fd_set rset, wset, xset;
	int maxfd;
	int rwx;
	int ret;

	FD_ZERO(&rset);
	FD_ZERO(&wset);
	FD_ZERO(&xset);
	maxfd = 0;

	FD_SET_MAX(signalpipe[0], maxfd, rset);

	if (connopen && !sending &&
	    back->socket(backhandle) != NULL &&
	    back->sendok(backhandle) &&
	    back->sendbuffer(backhandle) < MAX_STDIN_BACKLOG) {
	    /* If we're OK to send, then try to read from stdin. */
	    FD_SET_MAX(0, maxfd, rset);
	}

	if (bufchain_size(&stdout_data) > 0) {
	    /* If we have data for stdout, try to write to stdout. */
	    FD_SET_MAX(1, maxfd, wset);
	}

	if (bufchain_size(&stderr_data) > 0) {
	    /* If we have data for stderr, try to write to stderr. */
	    FD_SET_MAX(2, maxfd, wset);
	}

	/* Count the currently active sockets. */
	i = 0;
	for (socket = first_socket(&socketstate, &rwx); socket >= 0;
	     socket = next_socket(&socketstate, &rwx)) i++;

	/* Expand the sklist buffer if necessary. */
	if (i > sksize) {
	    sksize = i + 16;
	    sklist = srealloc(sklist, sksize * sizeof(*sklist));
	}

	/*
	 * Add all currently open sockets to the select sets, and
	 * store them in sklist as well.
	 */
	skcount = 0;
	for (socket = first_socket(&socketstate, &rwx); socket >= 0;
	     socket = next_socket(&socketstate, &rwx)) {
	    sklist[skcount++] = socket;
	    if (rwx & 1)
		FD_SET_MAX(socket, maxfd, rset);
	    if (rwx & 2)
		FD_SET_MAX(socket, maxfd, wset);
	    if (rwx & 4)
		FD_SET_MAX(socket, maxfd, xset);
	}

	do {
	    ret = select(maxfd, &rset, &wset, &xset, NULL);
	} while (ret < 0 && errno == EINTR);

	if (ret < 0) {
	    perror("select");
	    exit(1);
	}

	for (i = 0; i < skcount; i++) {
	    socket = sklist[i];
            /*
             * We must process exceptional notifications before
             * ordinary readability ones, or we may go straight
             * past the urgent marker.
             */
	    if (FD_ISSET(socket, &xset))
		select_result(socket, 4);
	    if (FD_ISSET(socket, &rset))
		select_result(socket, 1);
	    if (FD_ISSET(socket, &wset))
		select_result(socket, 2);
	}

	if (FD_ISSET(signalpipe[0], &rset)) {
	    char c[1];
	    struct winsize size;
	    read(signalpipe[0], c, 1); /* ignore its value; it'll be `x' */
	    if (ioctl(0, TIOCGWINSZ, (void *)&size) >= 0)
		back->size(backhandle, size.ws_col, size.ws_row);
	}

	if (FD_ISSET(0, &rset)) {
	    char buf[4096];
	    int ret;

	    if (connopen && back->socket(backhandle) != NULL) {
		ret = read(0, buf, sizeof(buf));
		if (ret < 0) {
		    perror("stdin: read");
		    exit(1);
		} else if (ret == 0) {
		    back->special(backhandle, TS_EOF);
		    sending = FALSE;   /* send nothing further after this */
		} else {
		    back->send(backhandle, buf, ret);
		}
	    }
	}

	if (FD_ISSET(1, &wset)) {
	    try_output(0);
	}

	if (FD_ISSET(2, &wset)) {
	    try_output(1);
	}

	if ((!connopen || back->socket(backhandle) == NULL) &&
	    bufchain_size(&stdout_data) == 0 &&
	    bufchain_size(&stderr_data) == 0)
	    break;		       /* we closed the connection */
    }
    exitcode = back->exitcode(backhandle);
    if (exitcode < 0) {
	fprintf(stderr, "Remote process exit code unavailable\n");
	exitcode = 1;		       /* this is an error condition */
    }
    cleanup_exit(exitcode);
    return exitcode;		       /* shouldn't happen, but placates gcc */
}