Remove all the "assert(len>0)" which forbade zero-length writes across the

[u/mdw/putty] / plink.c

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

#ifndef AUTO_WINSOCK
#include <winsock2.h>
#endif
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <stdarg.h>

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

#define WM_AGENT_CALLBACK (WM_XUSER + 4)

#define MAX_STDIN_BACKLOG 4096

struct agent_callback {
    void (*callback)(void *, void *, int);
    void *callback_ctx;
    void *data;
    int len;
};

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);
    WSACleanup();
    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);
    WSACleanup();
    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);
    WSACleanup();
    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);
}

HANDLE inhandle, outhandle, errhandle;
DWORD orig_console_mode;

WSAEVENT netevent;

static Backend *back;
static void *backhandle;
static Config cfg;

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. */
    DWORD mode;

    mode = ENABLE_PROCESSED_INPUT;
    if (echo)
	mode = mode | ENABLE_ECHO_INPUT;
    else
	mode = mode & ~ENABLE_ECHO_INPUT;
    if (edit)
	mode = mode | ENABLE_LINE_INPUT;
    else
	mode = mode & ~ENABLE_LINE_INPUT;
    SetConsoleMode(inhandle, mode);
}

struct input_data {
    DWORD len;
    char buffer[4096];
    HANDLE event, eventback;
};

static DWORD WINAPI stdin_read_thread(void *param)
{
    struct input_data *idata = (struct input_data *) param;
    HANDLE inhandle;

    inhandle = GetStdHandle(STD_INPUT_HANDLE);

    while (ReadFile(inhandle, idata->buffer, sizeof(idata->buffer),
		    &idata->len, NULL) && idata->len > 0) {
	SetEvent(idata->event);
	WaitForSingleObject(idata->eventback, INFINITE);
    }

    idata->len = 0;
    SetEvent(idata->event);

    return 0;
}

struct output_data {
    DWORD len, lenwritten;
    int writeret;
    char *buffer;
    int is_stderr, done;
    HANDLE event, eventback;
    int busy;
};

static DWORD WINAPI stdout_write_thread(void *param)
{
    struct output_data *odata = (struct output_data *) param;
    HANDLE outhandle, errhandle;

    outhandle = GetStdHandle(STD_OUTPUT_HANDLE);
    errhandle = GetStdHandle(STD_ERROR_HANDLE);

    while (1) {
	WaitForSingleObject(odata->eventback, INFINITE);
	if (odata->done)
	    break;
	odata->writeret =
	    WriteFile(odata->is_stderr ? errhandle : outhandle,
		      odata->buffer, odata->len, &odata->lenwritten, NULL);
	SetEvent(odata->event);
    }

    return 0;
}

bufchain stdout_data, stderr_data;
struct output_data odata, edata;

void try_output(int is_stderr)
{
    struct output_data *data = (is_stderr ? &edata : &odata);
    void *senddata;
    int sendlen;

    if (!data->busy) {
	bufchain_prefix(is_stderr ? &stderr_data : &stdout_data,
			&senddata, &sendlen);
	data->buffer = senddata;
	data->len = sendlen;
	SetEvent(data->eventback);
	data->busy = 1;
    }
}

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

    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;
}

static DWORD main_thread_id;

void agent_schedule_callback(void (*callback)(void *, void *, int),
			     void *callback_ctx, void *data, int len)
{
    struct agent_callback *c = snew(struct agent_callback);
    c->callback = callback;
    c->callback_ctx = callback_ctx;
    c->data = data;
    c->len = len;
    PostThreadMessage(main_thread_id, WM_AGENT_CALLBACK, 0, (LPARAM)c);
}

/*
 *  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("  -D listen-port   Dynamic SOCKS-based port forwarding\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");
    printf("  -s        remote command is an SSH subsystem (SSH-2 only)\n");
    exit(1);
}

char *do_select(SOCKET skt, int startup)
{
    int events;
    if (startup) {
	events = (FD_CONNECT | FD_READ | FD_WRITE |
		  FD_OOB | FD_CLOSE | FD_ACCEPT);
    } else {
	events = 0;
    }
    if (WSAEventSelect(skt, netevent, events) == SOCKET_ERROR) {
	switch (WSAGetLastError()) {
	  case WSAENETDOWN:
	    return "Network is down";
	  default:
	    return "WSAAsyncSelect(): unknown error";
	}
    }
    return NULL;
}

int main(int argc, char **argv)
{
    WSADATA wsadata;
    WORD winsock_ver;
    WSAEVENT stdinevent, stdoutevent, stderrevent;
    HANDLE handles[4];
    DWORD in_threadid, out_threadid, err_threadid;
    struct input_data idata;
    int reading;
    int sending;
    int portnumber = -1;
    SOCKET *sklist;
    int skcount, sksize;
    int connopen;
    int exitcode;
    int errors;
    int use_subsystem = 0;

    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, "-s")) {
		/* Save status to write to cfg later. */
		use_subsystem = 1;
	    } else {
		fprintf(stderr, "plink: unknown option \"%s\"\n", p);
		errors = 1;
	    }
	} else if (*p) {
	    if (!*cfg.host) {
		char *q = p;
		/*
		 * 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 = sresize(command, cmdsize, char);
			}
			command[cmdlen++]=*p++;
		    }
		    if (cmdlen >= cmdsize) {
			cmdsize = cmdlen + 512;
			command = sresize(command, cmdsize, char);
		    }
		    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);

    /*
     * Apply subsystem status.
     */
    if (use_subsystem)
	cfg.ssh_subsys = TRUE;

    /*
     * 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;

    /*
     * Initialise WinSock.
     */
    winsock_ver = MAKEWORD(2, 0);
    if (WSAStartup(winsock_ver, &wsadata)) {
	MessageBox(NULL, "Unable to initialise WinSock", "WinSock Error",
		   MB_OK | MB_ICONEXCLAMATION);
	return 1;
    }
    if (LOBYTE(wsadata.wVersion) != 2 || HIBYTE(wsadata.wVersion) != 0) {
	MessageBox(NULL, "WinSock version is incompatible with 2.0",
		   "WinSock Error", MB_OK | MB_ICONEXCLAMATION);
	WSACleanup();
	return 1;
    }
    sk_init();

    /*
     * Start up the connection.
     */
    netevent = CreateEvent(NULL, FALSE, FALSE, NULL);
    {
	const char *error;
	char *realhost;
	/* nodelay is only useful if stdin is a character device (console) */
	int nodelay = cfg.tcp_nodelay &&
	    (GetFileType(GetStdHandle(STD_INPUT_HANDLE)) == FILE_TYPE_CHAR);

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

    stdinevent = CreateEvent(NULL, FALSE, FALSE, NULL);
    stdoutevent = CreateEvent(NULL, FALSE, FALSE, NULL);
    stderrevent = CreateEvent(NULL, FALSE, FALSE, NULL);

    inhandle = GetStdHandle(STD_INPUT_HANDLE);
    outhandle = GetStdHandle(STD_OUTPUT_HANDLE);
    errhandle = GetStdHandle(STD_ERROR_HANDLE);
    GetConsoleMode(inhandle, &orig_console_mode);
    SetConsoleMode(inhandle, ENABLE_PROCESSED_INPUT);

    main_thread_id = GetCurrentThreadId();

    /*
     * Turn off ECHO and LINE input modes. We don't care if this
     * call fails, because we know we aren't necessarily running in
     * a console.
     */
    handles[0] = netevent;
    handles[1] = stdinevent;
    handles[2] = stdoutevent;
    handles[3] = stderrevent;
    sending = FALSE;

    /*
     * Create spare threads to write to stdout and stderr, so we
     * can arrange asynchronous writes.
     */
    odata.event = stdoutevent;
    odata.eventback = CreateEvent(NULL, FALSE, FALSE, NULL);
    odata.is_stderr = 0;
    odata.busy = odata.done = 0;
    if (!CreateThread(NULL, 0, stdout_write_thread,
		      &odata, 0, &out_threadid)) {
	fprintf(stderr, "Unable to create output thread\n");
	cleanup_exit(1);
    }
    edata.event = stderrevent;
    edata.eventback = CreateEvent(NULL, FALSE, FALSE, NULL);
    edata.is_stderr = 1;
    edata.busy = edata.done = 0;
    if (!CreateThread(NULL, 0, stdout_write_thread,
		      &edata, 0, &err_threadid)) {
	fprintf(stderr, "Unable to create error output thread\n");
	cleanup_exit(1);
    }

    while (1) {
	int n;

	if (!sending && back->sendok(backhandle)) {
	    /*
	     * Create a separate thread to read from stdin. This is
	     * a total pain, but I can't find another way to do it:
	     *
	     *  - an overlapped ReadFile or ReadFileEx just doesn't
	     *    happen; we get failure from ReadFileEx, and
	     *    ReadFile blocks despite being given an OVERLAPPED
	     *    structure. Perhaps we can't do overlapped reads
	     *    on consoles. WHY THE HELL NOT?
	     * 
	     *  - WaitForMultipleObjects(netevent, console) doesn't
	     *    work, because it signals the console when
	     *    _anything_ happens, including mouse motions and
	     *    other things that don't cause data to be readable
	     *    - so we're back to ReadFile blocking.
	     */
	    idata.event = stdinevent;
	    idata.eventback = CreateEvent(NULL, FALSE, FALSE, NULL);
	    if (!CreateThread(NULL, 0, stdin_read_thread,
			      &idata, 0, &in_threadid)) {
		fprintf(stderr, "Unable to create input thread\n");
		cleanup_exit(1);
	    }
	    sending = TRUE;
	}

	n = MsgWaitForMultipleObjects(4, handles, FALSE, INFINITE,
				      QS_POSTMESSAGE);
	if (n == 0) {
	    WSANETWORKEVENTS things;
	    SOCKET socket;
	    extern SOCKET first_socket(int *), next_socket(int *);
	    extern int select_result(WPARAM, LPARAM);
	    int i, socketstate;

	    /*
	     * We must not call select_result() for any socket
	     * until we have finished enumerating within the tree.
	     * This is because select_result() may close the socket
	     * and modify the tree.
	     */
	    /* Count the active sockets. */
	    i = 0;
	    for (socket = first_socket(&socketstate);
		 socket != INVALID_SOCKET;
		 socket = next_socket(&socketstate)) i++;

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

	    /* Retrieve the sockets into sklist. */
	    skcount = 0;
	    for (socket = first_socket(&socketstate);
		 socket != INVALID_SOCKET;
		 socket = next_socket(&socketstate)) {
		sklist[skcount++] = socket;
	    }

	    /* Now we're done enumerating; go through the list. */
	    for (i = 0; i < skcount; i++) {
		WPARAM wp;
		socket = sklist[i];
		wp = (WPARAM) socket;
		if (!WSAEnumNetworkEvents(socket, NULL, &things)) {
                    static const struct { int bit, mask; } eventtypes[] = {
                        {FD_CONNECT_BIT, FD_CONNECT},
                        {FD_READ_BIT, FD_READ},
                        {FD_CLOSE_BIT, FD_CLOSE},
                        {FD_OOB_BIT, FD_OOB},
                        {FD_WRITE_BIT, FD_WRITE},
                        {FD_ACCEPT_BIT, FD_ACCEPT},
                    };
                    int e;

		    noise_ultralight(socket);
		    noise_ultralight(things.lNetworkEvents);

                    for (e = 0; e < lenof(eventtypes); e++)
                        if (things.lNetworkEvents & eventtypes[e].mask) {
                            LPARAM lp;
                            int err = things.iErrorCode[eventtypes[e].bit];
                            lp = WSAMAKESELECTREPLY(eventtypes[e].mask, err);
                            connopen &= select_result(wp, lp);
                        }
		}
	    }
	} else if (n == 1) {
	    reading = 0;
	    noise_ultralight(idata.len);
	    if (connopen && back->socket(backhandle) != NULL) {
		if (idata.len > 0) {
		    back->send(backhandle, idata.buffer, idata.len);
		} else {
		    back->special(backhandle, TS_EOF);
		}
	    }
	} else if (n == 2) {
	    odata.busy = 0;
	    if (!odata.writeret) {
		fprintf(stderr, "Unable to write to standard output\n");
		cleanup_exit(0);
	    }
	    bufchain_consume(&stdout_data, odata.lenwritten);
	    if (bufchain_size(&stdout_data) > 0)
		try_output(0);
	    if (connopen && back->socket(backhandle) != NULL) {
		back->unthrottle(backhandle, bufchain_size(&stdout_data) +
				 bufchain_size(&stderr_data));
	    }
	} else if (n == 3) {
	    edata.busy = 0;
	    if (!edata.writeret) {
		fprintf(stderr, "Unable to write to standard output\n");
		cleanup_exit(0);
	    }
	    bufchain_consume(&stderr_data, edata.lenwritten);
	    if (bufchain_size(&stderr_data) > 0)
		try_output(1);
	    if (connopen && back->socket(backhandle) != NULL) {
		back->unthrottle(backhandle, bufchain_size(&stdout_data) +
				 bufchain_size(&stderr_data));
	    }
	} else if (n == 4) {
	    MSG msg;
	    while (PeekMessage(&msg, INVALID_HANDLE_VALUE,
			       WM_AGENT_CALLBACK, WM_AGENT_CALLBACK,
			       PM_REMOVE)) {
		struct agent_callback *c = (struct agent_callback *)msg.lParam;
		c->callback(c->callback_ctx, c->data, c->len);
		sfree(c);
	    }
	}
	if (!reading && back->sendbuffer(backhandle) < MAX_STDIN_BACKLOG) {
	    SetEvent(idata.eventback);
	    reading = 1;
	}
	if ((!connopen || back->socket(backhandle) == NULL) &&
	    bufchain_size(&stdout_data) == 0 &&
	    bufchain_size(&stderr_data) == 0)
	    break;		       /* we closed the connection */
    }
    WSACleanup();
    exitcode = back->exitcode(backhandle);
    if (exitcode < 0) {
	fprintf(stderr, "Remote process exit code unavailable\n");
	exitcode = 1;		       /* this is an error condition */
    }
    return exitcode;
}