[u/mdw/putty] / x11fwd.c

/*
 * Platform-independent bits of X11 forwarding.
 */

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <time.h>

#include "putty.h"
#include "ssh.h"

#define GET_32BIT_LSB_FIRST(cp) \
  (((unsigned long)(unsigned char)(cp)[0]) | \
  ((unsigned long)(unsigned char)(cp)[1] << 8) | \
  ((unsigned long)(unsigned char)(cp)[2] << 16) | \
  ((unsigned long)(unsigned char)(cp)[3] << 24))

#define PUT_32BIT_LSB_FIRST(cp, value) ( \
  (cp)[0] = (char)(value), \
  (cp)[1] = (char)((value) >> 8), \
  (cp)[2] = (char)((value) >> 16), \
  (cp)[3] = (char)((value) >> 24) )

#define GET_16BIT_LSB_FIRST(cp) \
  (((unsigned long)(unsigned char)(cp)[0]) | \
  ((unsigned long)(unsigned char)(cp)[1] << 8))

#define PUT_16BIT_LSB_FIRST(cp, value) ( \
  (cp)[0] = (char)(value), \
  (cp)[1] = (char)((value) >> 8) )

#define GET_32BIT_MSB_FIRST(cp) \
  (((unsigned long)(unsigned char)(cp)[0] << 24) | \
  ((unsigned long)(unsigned char)(cp)[1] << 16) | \
  ((unsigned long)(unsigned char)(cp)[2] << 8) | \
  ((unsigned long)(unsigned char)(cp)[3]))

#define PUT_32BIT_MSB_FIRST(cp, value) ( \
  (cp)[0] = (char)((value) >> 24), \
  (cp)[1] = (char)((value) >> 16), \
  (cp)[2] = (char)((value) >> 8), \
  (cp)[3] = (char)(value) )

#define GET_16BIT_MSB_FIRST(cp) \
  (((unsigned long)(unsigned char)(cp)[0] << 8) | \
  ((unsigned long)(unsigned char)(cp)[1]))

#define PUT_16BIT_MSB_FIRST(cp, value) ( \
  (cp)[0] = (char)((value) >> 8), \
  (cp)[1] = (char)(value) )

#define GET_16BIT(endian, cp) \
  (endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))

#define PUT_16BIT(endian, cp, val) \
  (endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))

const char *const x11_authnames[] = {
    "", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
};

struct X11Auth {
    unsigned char fakedata[64], realdata[64];
    int fakeproto, realproto;
    int fakelen, reallen;
};

struct X11Private {
    const struct plug_function_table *fn;
    /* the above variable absolutely *must* be the first in this structure */
    unsigned char firstpkt[12];	       /* first X data packet */
    struct X11Auth *auth;
    char *auth_protocol;
    unsigned char *auth_data;
    int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
    int verified;
    int throttled, throttle_override;
    unsigned long peer_ip;
    int peer_port;
    void *c;			       /* data used by ssh.c */
    Socket s;
};

void *x11_invent_auth(char *proto, int protomaxlen,
		      char *data, int datamaxlen, int proto_id)
{
    struct X11Auth *auth = snew(struct X11Auth);
    char ourdata[64];
    int i;

    if (proto_id == X11_MIT) {
	auth->fakeproto = X11_MIT;

	/* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
	auth->fakelen = 16;
	for (i = 0; i < 16; i++)
	    auth->fakedata[i] = random_byte();
    } else {
	assert(proto_id == X11_XDM);
	auth->fakeproto = X11_XDM;

	/* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
	auth->fakelen = 16;
	for (i = 0; i < 16; i++)
	    auth->fakedata[i] = (i == 8 ? 0 : random_byte());
    }

    /* Now format for the recipient. */
    strncpy(proto, x11_authnames[auth->fakeproto], protomaxlen);
    ourdata[0] = '\0';
    for (i = 0; i < auth->fakelen; i++)
	sprintf(ourdata + strlen(ourdata), "%02x", auth->fakedata[i]);
    strncpy(data, ourdata, datamaxlen);

    return auth;
}

void x11_free_auth(void *auth)
{

    sfree(auth);
}

/*
 * Fetch the real auth data for a given display string, and store
 * it in an X11Auth structure. Returns NULL on success, or an error
 * string.
 */
void x11_get_real_auth(void *authv, char *display)
{
    struct X11Auth *auth = (struct X11Auth *)authv;

    auth->realproto = X11_NO_AUTH;     /* in case next call does nothing */

    auth->reallen = sizeof(auth->realdata);
    platform_get_x11_auth(display, &auth->realproto,
                          auth->realdata, &auth->reallen);
}

static char *x11_verify(unsigned long peer_ip, int peer_port,
			struct X11Auth *auth, char *proto,
			unsigned char *data, int dlen)
{
    if (strcmp(proto, x11_authnames[auth->fakeproto]) != 0)
	return "wrong authentication protocol attempted";
    if (auth->fakeproto == X11_MIT) {
        if (dlen != auth->fakelen)
            return "MIT-MAGIC-COOKIE-1 data was wrong length";
        if (memcmp(auth->fakedata, data, dlen) != 0)
            return "MIT-MAGIC-COOKIE-1 data did not match";
    }
    if (auth->fakeproto == X11_XDM) {
	unsigned long t;
	time_t tim;
	int i;

        if (dlen != 24)
            return "XDM-AUTHORIZATION-1 data was wrong length";
	if (peer_port == -1)
            return "cannot do XDM-AUTHORIZATION-1 without remote address data";
	des_decrypt_xdmauth(auth->fakedata+9, data, 24);
        if (memcmp(auth->fakedata, data, 8) != 0)
            return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
	if (GET_32BIT_MSB_FIRST(data+8) != peer_ip)
            return "XDM-AUTHORIZATION-1 data failed check";   /* IP wrong */
	if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port)
            return "XDM-AUTHORIZATION-1 data failed check";   /* port wrong */
	t = GET_32BIT_MSB_FIRST(data+14);
	for (i = 18; i < 24; i++)
	    if (data[i] != 0)	       /* zero padding wrong */
		return "XDM-AUTHORIZATION-1 data failed check";
	tim = time(NULL);
	if (abs(t - tim) > 20*60)      /* 20 minute clock skew should be OK */
	    return "XDM-AUTHORIZATION-1 time stamp was too far out";
    }
    /* implement other protocols here if ever required */
    return NULL;
}

static int x11_closing(Plug plug, const char *error_msg, int error_code,
		       int calling_back)
{
    struct X11Private *pr = (struct X11Private *) plug;

    /*
     * We have no way to communicate down the forwarded connection,
     * so if an error occurred on the socket, we just ignore it
     * and treat it like a proper close.
     */
    sshfwd_close(pr->c);
    x11_close(pr->s);
    return 1;
}

static int x11_receive(Plug plug, int urgent, char *data, int len)
{
    struct X11Private *pr = (struct X11Private *) plug;

    if (sshfwd_write(pr->c, data, len) > 0) {
	pr->throttled = 1;
	sk_set_frozen(pr->s, 1);
    }

    return 1;
}

static void x11_sent(Plug plug, int bufsize)
{
    struct X11Private *pr = (struct X11Private *) plug;

    sshfwd_unthrottle(pr->c, bufsize);
}

/*
 * When setting up X forwarding, we should send the screen number
 * from the specified local display. This function extracts it from
 * the display string.
 */
int x11_get_screen_number(char *display)
{
    int n;

    n = strcspn(display, ":");
    if (!display[n])
	return 0;
    n = strcspn(display, ".");
    if (!display[n])
	return 0;
    return atoi(display + n + 1);
}

/* Find the right display, returns an allocated string */
char *x11_display(const char *display) {
    char *ret;
    if(!display || !*display) {
	/* try to find platform-specific local display */
	if(!(ret = platform_get_x_display()))
	    /* plausible default for all platforms */
	    ret = dupstr(":0");
    } else
	ret = dupstr(display);
    if(ret[0] == ':') {
	/* no transport specified, use whatever we think is best */
	char *s = dupcat(platform_x11_best_transport, ret, (char *)0);
	sfree(ret);
	return s;
    } else
	return ret;
}

/*
 * Called to set up the raw connection.
 * 
 * Returns an error message, or NULL on success.
 * also, fills the SocketsStructure
 */
const char *x11_init(Socket * s, char *display, void *c, void *auth,
		     const char *peeraddr, int peerport, const Config *cfg)
{
    static const struct plug_function_table fn_table = {
	x11_closing,
	x11_receive,
	x11_sent,
	NULL
    };

    SockAddr addr;
    int port;
    const char *err;
    char *dummy_realhost;
    char host[128];
    int n, displaynum;
    struct X11Private *pr;

    /* default display */
    display = x11_display(display);
    /*
     * Split up display name into host and display-number parts.
     */
    n = strcspn(display, ":");
    assert(n != 0);		/* x11_display() promises this */
    if (display[n])
	displaynum = atoi(display + n + 1);
    else
	displaynum = 0;		       /* sensible default */
    if (n > sizeof(host) - 1)
	n = sizeof(host) - 1;
    strncpy(host, display, n);
    host[n] = '\0';
    sfree(display);
    
    if(!strcmp(host, "unix")) {
	/* use AF_UNIX sockets (doesn't make sense on all platforms) */
	addr = platform_get_x11_unix_address(displaynum,
					     &dummy_realhost);
	port = 0;		/* to show we are not confused */
    } else {
	port = 6000 + displaynum;
	
	/*
	 * Try to find host.
	 */
	addr = name_lookup(host, port, &dummy_realhost, cfg, ADDRTYPE_UNSPEC);
	if ((err = sk_addr_error(addr)) != NULL) {
	    sk_addr_free(addr);
	    return err;
	}
    }

    /*
     * Open socket.
     */
    pr = snew(struct X11Private);
    pr->fn = &fn_table;
    pr->auth_protocol = NULL;
    pr->auth = (struct X11Auth *)auth;
    pr->verified = 0;
    pr->data_read = 0;
    pr->throttled = pr->throttle_override = 0;
    pr->c = c;

    pr->s = *s = new_connection(addr, dummy_realhost, port,
				0, 1, 0, 0, (Plug) pr, cfg);
    if ((err = sk_socket_error(*s)) != NULL) {
	sfree(pr);
	return err;
    }

    /*
     * See if we can make sense of the peer address we were given.
     */
    {
	int i[4];
	if (peeraddr &&
	    4 == sscanf(peeraddr, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {
	    pr->peer_ip = (i[0] << 24) | (i[1] << 16) | (i[2] << 8) | i[3];
	    pr->peer_port = peerport;
	} else {
	    pr->peer_ip = 0;
	    pr->peer_port = -1;
	}
    }

    sk_set_private_ptr(*s, pr);
    return NULL;
}

void x11_close(Socket s)
{
    struct X11Private *pr;
    if (!s)
	return;
    pr = (struct X11Private *) sk_get_private_ptr(s);
    if (pr->auth_protocol) {
	sfree(pr->auth_protocol);
	sfree(pr->auth_data);
    }

    sfree(pr);

    sk_close(s);
}

void x11_unthrottle(Socket s)
{
    struct X11Private *pr;
    if (!s)
	return;
    pr = (struct X11Private *) sk_get_private_ptr(s);

    pr->throttled = 0;
    sk_set_frozen(s, pr->throttled || pr->throttle_override);
}

void x11_override_throttle(Socket s, int enable)
{
    struct X11Private *pr;
    if (!s)
	return;
    pr = (struct X11Private *) sk_get_private_ptr(s);

    pr->throttle_override = enable;
    sk_set_frozen(s, pr->throttled || pr->throttle_override);
}

/*
 * Called to send data down the raw connection.
 */
int x11_send(Socket s, char *data, int len)
{
    struct X11Private *pr;
    if (!s)
	return 0;
    pr = (struct X11Private *) sk_get_private_ptr(s);

    /*
     * Read the first packet.
     */
    while (len > 0 && pr->data_read < 12)
	pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++);
    if (pr->data_read < 12)
	return 0;

    /*
     * If we have not allocated the auth_protocol and auth_data
     * strings, do so now.
     */
    if (!pr->auth_protocol) {
	pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6);
	pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8);
	pr->auth_psize = (pr->auth_plen + 3) & ~3;
	pr->auth_dsize = (pr->auth_dlen + 3) & ~3;
	/* Leave room for a terminating zero, to make our lives easier. */
	pr->auth_protocol = snewn(pr->auth_psize + 1, char);
	pr->auth_data = snewn(pr->auth_dsize, unsigned char);
    }

    /*
     * Read the auth_protocol and auth_data strings.
     */
    while (len > 0 && pr->data_read < 12 + pr->auth_psize)
	pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++);
    while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
	pr->auth_data[pr->data_read++ - 12 -
		      pr->auth_psize] = (unsigned char) (len--, *data++);
    if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
	return 0;

    /*
     * If we haven't verified the authentication, do so now.
     */
    if (!pr->verified) {
	char *err;

	pr->auth_protocol[pr->auth_plen] = '\0';	/* ASCIZ */
	err = x11_verify(pr->peer_ip, pr->peer_port,
			 pr->auth, pr->auth_protocol,
			 pr->auth_data, pr->auth_dlen);

	/*
	 * If authentication failed, construct and send an error
	 * packet, then terminate the connection.
	 */
	if (err) {
	    char *message;
	    int msglen, msgsize;
	    unsigned char *reply;

	    message = dupprintf("PuTTY X11 proxy: %s", err);
	    msglen = strlen(message);
	    reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */
	    msgsize = (msglen + 3) & ~3;
	    reply[0] = 0;	       /* failure */
	    reply[1] = msglen;	       /* length of reason string */
	    memcpy(reply + 2, pr->firstpkt + 2, 4);	/* major/minor proto vsn */
	    PUT_16BIT(pr->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
	    memset(reply + 8, 0, msgsize);
	    memcpy(reply + 8, message, msglen);
	    sshfwd_write(pr->c, (char *)reply, 8 + msgsize);
	    sshfwd_close(pr->c);
	    x11_close(s);
	    sfree(reply);
	    sfree(message);
	    return 0;
	}

	/*
	 * Now we know we're going to accept the connection. Strip
	 * the fake auth data, and optionally put real auth data in
	 * instead.
	 */
        {
            char realauthdata[64];
            int realauthlen = 0;
            int authstrlen = strlen(x11_authnames[pr->auth->realproto]);
	    unsigned long ip;
	    int port;
            static const char zeroes[4] = { 0,0,0,0 };

            if (pr->auth->realproto == X11_MIT) {
                assert(pr->auth->reallen <= lenof(realauthdata));
                realauthlen = pr->auth->reallen;
                memcpy(realauthdata, pr->auth->realdata, realauthlen);
            } else if (pr->auth->realproto == X11_XDM &&
		       pr->auth->reallen == 16 &&
		       sk_getxdmdata(s, &ip, &port)) {
		time_t t;
                realauthlen = 24;
		memset(realauthdata, 0, 24);
		memcpy(realauthdata, pr->auth->realdata, 8);
		PUT_32BIT_MSB_FIRST(realauthdata+8, ip);
		PUT_16BIT_MSB_FIRST(realauthdata+12, port);
		t = time(NULL);
		PUT_32BIT_MSB_FIRST(realauthdata+14, t);
		des_encrypt_xdmauth(pr->auth->realdata+9,
				    (unsigned char *)realauthdata, 24);
	    }
            /* implement other auth methods here if required */

            PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, authstrlen);
            PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, realauthlen);
        
            sk_write(s, (char *)pr->firstpkt, 12);

            if (authstrlen) {
                sk_write(s, x11_authnames[pr->auth->realproto], authstrlen);
                sk_write(s, zeroes, 3 & (-authstrlen));
            }
            if (realauthlen) {
                sk_write(s, realauthdata, realauthlen);
                sk_write(s, zeroes, 3 & (-realauthlen));
            }
        }
	pr->verified = 1;
    }

    /*
     * After initialisation, just copy data simply.
     */

    return sk_write(s, data, len);
}
Commit	Line	Data
46ed7b64	1	/*
	2	* Platform-independent bits of X11 forwarding.
	3	*/
	4
9c964e85	5	#include <stdio.h>
9c964e85	6	#include <stdlib.h>
e0e7dff8	7	#include <assert.h>
2f92b717	8	#include <time.h>
9c964e85	9
	10	#include "putty.h"
	11	#include "ssh.h"
	12
9c964e85	13	#define GET_32BIT_LSB_FIRST(cp) \
	14	(((unsigned long)(unsigned char)(cp)[0]) \| \
	15	((unsigned long)(unsigned char)(cp)[1] << 8) \| \
	16	((unsigned long)(unsigned char)(cp)[2] << 16) \| \
	17	((unsigned long)(unsigned char)(cp)[3] << 24))
	18
	19	#define PUT_32BIT_LSB_FIRST(cp, value) ( \
b3ebaa28	20	(cp)[0] = (char)(value), \
	21	(cp)[1] = (char)((value) >> 8), \
	22	(cp)[2] = (char)((value) >> 16), \
	23	(cp)[3] = (char)((value) >> 24) )
9c964e85	24
	25	#define GET_16BIT_LSB_FIRST(cp) \
	26	(((unsigned long)(unsigned char)(cp)[0]) \| \
	27	((unsigned long)(unsigned char)(cp)[1] << 8))
	28
	29	#define PUT_16BIT_LSB_FIRST(cp, value) ( \
b3ebaa28	30	(cp)[0] = (char)(value), \
b3ebaa28	31	(cp)[1] = (char)((value) >> 8) )
9c964e85	32
	33	#define GET_32BIT_MSB_FIRST(cp) \
	34	(((unsigned long)(unsigned char)(cp)[0] << 24) \| \
	35	((unsigned long)(unsigned char)(cp)[1] << 16) \| \
	36	((unsigned long)(unsigned char)(cp)[2] << 8) \| \
	37	((unsigned long)(unsigned char)(cp)[3]))
	38
	39	#define PUT_32BIT_MSB_FIRST(cp, value) ( \
b3ebaa28	40	(cp)[0] = (char)((value) >> 24), \
	41	(cp)[1] = (char)((value) >> 16), \
	42	(cp)[2] = (char)((value) >> 8), \
	43	(cp)[3] = (char)(value) )
9c964e85	44
	45	#define GET_16BIT_MSB_FIRST(cp) \
	46	(((unsigned long)(unsigned char)(cp)[0] << 8) \| \
	47	((unsigned long)(unsigned char)(cp)[1]))
	48
	49	#define PUT_16BIT_MSB_FIRST(cp, value) ( \
b3ebaa28	50	(cp)[0] = (char)((value) >> 8), \
b3ebaa28	51	(cp)[1] = (char)(value) )
9c964e85	52
	53	#define GET_16BIT(endian, cp) \
	54	(endian=='B' ? GET_16BIT_MSB_FIRST(cp) : GET_16BIT_LSB_FIRST(cp))
	55
	56	#define PUT_16BIT(endian, cp, val) \
	57	(endian=='B' ? PUT_16BIT_MSB_FIRST(cp, val) : PUT_16BIT_LSB_FIRST(cp, val))
	58
e0e7dff8	59	const char *const x11_authnames[] = {
2f92b717	60	"", "MIT-MAGIC-COOKIE-1", "XDM-AUTHORIZATION-1"
e0e7dff8	61	};
e0e7dff8	62
302121de	63	struct X11Auth {
e0e7dff8	64	unsigned char fakedata[64], realdata[64];
	65	int fakeproto, realproto;
	66	int fakelen, reallen;
302121de	67	};
302121de	68
9c964e85	69	struct X11Private {
302121de	70	const struct plug_function_table *fn;
7e78000d	71	/* the above variable absolutely must be the first in this structure */
32874aea	72	unsigned char firstpkt[12]; /* first X data packet */
302121de	73	struct X11Auth *auth;
9c964e85	74	char *auth_protocol;
	75	unsigned char *auth_data;
	76	int data_read, auth_plen, auth_psize, auth_dlen, auth_dsize;
	77	int verified;
5471d09a	78	int throttled, throttle_override;
b3ebaa28	79	unsigned long peer_ip;
b3ebaa28	80	int peer_port;
32874aea	81	void c; / data used by ssh.c */
7e78000d	82	Socket s;
9c964e85	83	};
9c964e85	84
302121de	85	void x11_invent_auth(char proto, int protomaxlen,
b3ebaa28	86	char *data, int datamaxlen, int proto_id)
32874aea	87	{
3d88e64d	88	struct X11Auth *auth = snew(struct X11Auth);
9c964e85	89	char ourdata[64];
	90	int i;
	91
b3ebaa28	92	if (proto_id == X11_MIT) {
b3ebaa28	93	auth->fakeproto = X11_MIT;
e0e7dff8	94
b3ebaa28	95	/* MIT-MAGIC-COOKIE-1. Cookie size is 128 bits (16 bytes). */
	96	auth->fakelen = 16;
	97	for (i = 0; i < 16; i++)
	98	auth->fakedata[i] = random_byte();
	99	} else {
	100	assert(proto_id == X11_XDM);
	101	auth->fakeproto = X11_XDM;
	102
	103	/* XDM-AUTHORIZATION-1. Cookie size is 16 bytes; byte 8 is zero. */
	104	auth->fakelen = 16;
	105	for (i = 0; i < 16; i++)
	106	auth->fakedata[i] = (i == 8 ? 0 : random_byte());
	107	}
9c964e85	108
9c964e85	109	/* Now format for the recipient. */
e0e7dff8	110	strncpy(proto, x11_authnames[auth->fakeproto], protomaxlen);
9c964e85	111	ourdata[0] = '\0';
e0e7dff8	112	for (i = 0; i < auth->fakelen; i++)
e0e7dff8	113	sprintf(ourdata + strlen(ourdata), "%02x", auth->fakedata[i]);
9c964e85	114	strncpy(data, ourdata, datamaxlen);
302121de	115
302121de	116	return auth;
9c964e85	117	}
9c964e85	118
fabd1805	119	void x11_free_auth(void *auth)
	120	{
	121
	122	sfree(auth);
	123	}
	124
e0e7dff8	125	/*
	126	* Fetch the real auth data for a given display string, and store
	127	* it in an X11Auth structure. Returns NULL on success, or an error
	128	* string.
	129	*/
	130	void x11_get_real_auth(void authv, char display)
	131	{
	132	struct X11Auth auth = (struct X11Auth )authv;
	133
	134	auth->realproto = X11_NO_AUTH; /* in case next call does nothing */
	135
	136	auth->reallen = sizeof(auth->realdata);
	137	platform_get_x11_auth(display, &auth->realproto,
	138	auth->realdata, &auth->reallen);
	139	}
	140
b3ebaa28	141	static char *x11_verify(unsigned long peer_ip, int peer_port,
	142	struct X11Auth auth, char proto,
	143	unsigned char *data, int dlen)
32874aea	144	{
e0e7dff8	145	if (strcmp(proto, x11_authnames[auth->fakeproto]) != 0)
b3ebaa28	146	return "wrong authentication protocol attempted";
e0e7dff8	147	if (auth->fakeproto == X11_MIT) {
e0e7dff8	148	if (dlen != auth->fakelen)
b3ebaa28	149	return "MIT-MAGIC-COOKIE-1 data was wrong length";
e0e7dff8	150	if (memcmp(auth->fakedata, data, dlen) != 0)
b3ebaa28	151	return "MIT-MAGIC-COOKIE-1 data did not match";
	152	}
	153	if (auth->fakeproto == X11_XDM) {
	154	unsigned long t;
	155	time_t tim;
	156	int i;
	157
	158	if (dlen != 24)
	159	return "XDM-AUTHORIZATION-1 data was wrong length";
	160	if (peer_port == -1)
	161	return "cannot do XDM-AUTHORIZATION-1 without remote address data";
	162	des_decrypt_xdmauth(auth->fakedata+9, data, 24);
	163	if (memcmp(auth->fakedata, data, 8) != 0)
	164	return "XDM-AUTHORIZATION-1 data failed check"; /* cookie wrong */
	165	if (GET_32BIT_MSB_FIRST(data+8) != peer_ip)
	166	return "XDM-AUTHORIZATION-1 data failed check"; /* IP wrong */
	167	if ((int)GET_16BIT_MSB_FIRST(data+12) != peer_port)
	168	return "XDM-AUTHORIZATION-1 data failed check"; /* port wrong */
	169	t = GET_32BIT_MSB_FIRST(data+14);
	170	for (i = 18; i < 24; i++)
	171	if (data[i] != 0) /* zero padding wrong */
	172	return "XDM-AUTHORIZATION-1 data failed check";
	173	tim = time(NULL);
	174	if (abs(t - tim) > 2060) / 20 minute clock skew should be OK */
	175	return "XDM-AUTHORIZATION-1 time stamp was too far out";
e0e7dff8	176	}
e0e7dff8	177	/* implement other protocols here if ever required */
b3ebaa28	178	return NULL;
9c964e85	179	}
9c964e85	180
cbe2d68f	181	static int x11_closing(Plug plug, const char *error_msg, int error_code,
32874aea	182	int calling_back)
32874aea	183	{
7e78000d	184	struct X11Private pr = (struct X11Private ) plug;
	185
	186	/*
	187	* We have no way to communicate down the forwarded connection,
	188	* so if an error occurred on the socket, we just ignore it
	189	* and treat it like a proper close.
	190	*/
	191	sshfwd_close(pr->c);
	192	x11_close(pr->s);
	193	return 1;
	194	}
	195
32874aea	196	static int x11_receive(Plug plug, int urgent, char *data, int len)
32874aea	197	{
7e78000d	198	struct X11Private pr = (struct X11Private ) plug;
9c964e85	199
5471d09a	200	if (sshfwd_write(pr->c, data, len) > 0) {
	201	pr->throttled = 1;
	202	sk_set_frozen(pr->s, 1);
	203	}
	204
9c964e85	205	return 1;
	206	}
	207
5471d09a	208	static void x11_sent(Plug plug, int bufsize)
	209	{
	210	struct X11Private pr = (struct X11Private ) plug;
	211
	212	sshfwd_unthrottle(pr->c, bufsize);
	213	}
	214
9c964e85	215	/*
421d6835	216	* When setting up X forwarding, we should send the screen number
	217	* from the specified local display. This function extracts it from
	218	* the display string.
	219	*/
	220	int x11_get_screen_number(char *display)
	221	{
	222	int n;
	223
	224	n = strcspn(display, ":");
	225	if (!display[n])
	226	return 0;
	227	n = strcspn(display, ".");
	228	if (!display[n])
	229	return 0;
	230	return atoi(display + n + 1);
	231	}
	232
fc0f17db	233	/* Find the right display, returns an allocated string */
fc0f17db	234	char x11_display(const char display) {
46ed7b64	235	char *ret;
	236	if(!display \|\| !*display) {
	237	/* try to find platform-specific local display */
	238	if(!(ret = platform_get_x_display()))
	239	/* plausible default for all platforms */
	240	ret = dupstr(":0");
	241	} else
	242	ret = dupstr(display);
	243	if(ret[0] == ':') {
fc0f17db	244	/* no transport specified, use whatever we think is best */
0ca70bfc	245	char s = dupcat(platform_x11_best_transport, ret, (char )0);
46ed7b64	246	sfree(ret);
46ed7b64	247	return s;
fc0f17db	248	} else
46ed7b64	249	return ret;
fc0f17db	250	}
fc0f17db	251
421d6835	252	/*
9c964e85	253	* Called to set up the raw connection.
	254	*
	255	* Returns an error message, or NULL on success.
	256	* also, fills the SocketsStructure
9c964e85	257	*/
cbe2d68f	258	const char x11_init(Socket s, char display, void c, void *auth,
cbe2d68f	259	const char peeraddr, int peerport, const Config cfg)
32874aea	260	{
302121de	261	static const struct plug_function_table fn_table = {
7e78000d	262	x11_closing,
5471d09a	263	x11_receive,
	264	x11_sent,
	265	NULL
7e78000d	266	};
7e78000d	267
9c964e85	268	SockAddr addr;
9c964e85	269	int port;
cbe2d68f	270	const char *err;
cbe2d68f	271	char *dummy_realhost;
9c964e85	272	char host[128];
	273	int n, displaynum;
	274	struct X11Private *pr;
	275
fc0f17db	276	/* default display */
fc0f17db	277	display = x11_display(display);
9c964e85	278	/*
	279	* Split up display name into host and display-number parts.
	280	*/
	281	n = strcspn(display, ":");
fc0f17db	282	assert(n != 0); /* x11_display() promises this */
9c964e85	283	if (display[n])
32874aea	284	displaynum = atoi(display + n + 1);
9c964e85	285	else
32874aea	286	displaynum = 0; /* sensible default */
	287	if (n > sizeof(host) - 1)
	288	n = sizeof(host) - 1;
fc0f17db	289	strncpy(host, display, n);
	290	host[n] = '\0';
	291	sfree(display);
	292
	293	if(!strcmp(host, "unix")) {
	294	/* use AF_UNIX sockets (doesn't make sense on all platforms) */
	295	addr = platform_get_x11_unix_address(displaynum,
	296	&dummy_realhost);
	297	port = 0; /* to show we are not confused */
ecc0ba5b	298	} else {
fc0f17db	299	port = 6000 + displaynum;
fc0f17db	300
ecc0ba5b	301	/*
fc0f17db	302	* Try to find host.
ecc0ba5b	303	*/
05581745	304	addr = name_lookup(host, port, &dummy_realhost, cfg, ADDRTYPE_UNSPEC);
fc0f17db	305	if ((err = sk_addr_error(addr)) != NULL) {
	306	sk_addr_free(addr);
	307	return err;
	308	}
f85e6f6e	309	}
9c964e85	310
9c964e85	311	/*
	312	* Open socket.
	313	*/
3d88e64d	314	pr = snew(struct X11Private);
7e78000d	315	pr->fn = &fn_table;
9c964e85	316	pr->auth_protocol = NULL;
302121de	317	pr->auth = (struct X11Auth *)auth;
9c964e85	318	pr->verified = 0;
9c964e85	319	pr->data_read = 0;
5471d09a	320	pr->throttled = pr->throttle_override = 0;
9c964e85	321	pr->c = c;
9c964e85	322
e8fa8f62	323	pr->s = *s = new_connection(addr, dummy_realhost, port,
79bf227b	324	0, 1, 0, 0, (Plug) pr, cfg);
6518ea7b	325	if ((err = sk_socket_error(*s)) != NULL) {
32874aea	326	sfree(pr);
7e78000d	327	return err;
	328	}
	329
b3ebaa28	330	/*
	331	* See if we can make sense of the peer address we were given.
	332	*/
	333	{
	334	int i[4];
	335	if (peeraddr &&
	336	4 == sscanf(peeraddr, "%d.%d.%d.%d", i+0, i+1, i+2, i+3)) {
	337	pr->peer_ip = (i[0] << 24) \| (i[1] << 16) \| (i[2] << 8) \| i[3];
	338	pr->peer_port = peerport;
	339	} else {
	340	pr->peer_ip = 0;
	341	pr->peer_port = -1;
	342	}
	343	}
	344
9c964e85	345	sk_set_private_ptr(*s, pr);
9c964e85	346	return NULL;
	347	}
	348
32874aea	349	void x11_close(Socket s)
	350	{
	351	struct X11Private *pr;
d74d141c	352	if (!s)
	353	return;
	354	pr = (struct X11Private *) sk_get_private_ptr(s);
9c964e85	355	if (pr->auth_protocol) {
32874aea	356	sfree(pr->auth_protocol);
32874aea	357	sfree(pr->auth_data);
9c964e85	358	}
	359
	360	sfree(pr);
	361
	362	sk_close(s);
	363	}
	364
5471d09a	365	void x11_unthrottle(Socket s)
	366	{
	367	struct X11Private *pr;
	368	if (!s)
	369	return;
	370	pr = (struct X11Private *) sk_get_private_ptr(s);
	371
	372	pr->throttled = 0;
	373	sk_set_frozen(s, pr->throttled \|\| pr->throttle_override);
	374	}
	375
	376	void x11_override_throttle(Socket s, int enable)
	377	{
	378	struct X11Private *pr;
	379	if (!s)
	380	return;
	381	pr = (struct X11Private *) sk_get_private_ptr(s);
	382
	383	pr->throttle_override = enable;
	384	sk_set_frozen(s, pr->throttled \|\| pr->throttle_override);
	385	}
	386
9c964e85	387	/*
	388	* Called to send data down the raw connection.
	389	*/
5471d09a	390	int x11_send(Socket s, char *data, int len)
32874aea	391	{
970f2b02	392	struct X11Private *pr;
970f2b02	393	if (!s)
5471d09a	394	return 0;
970f2b02	395	pr = (struct X11Private *) sk_get_private_ptr(s);
9c964e85	396
	397	/*
	398	* Read the first packet.
	399	*/
	400	while (len > 0 && pr->data_read < 12)
32874aea	401	pr->firstpkt[pr->data_read++] = (unsigned char) (len--, *data++);
9c964e85	402	if (pr->data_read < 12)
5471d09a	403	return 0;
9c964e85	404
	405	/*
	406	* If we have not allocated the auth_protocol and auth_data
	407	* strings, do so now.
	408	*/
	409	if (!pr->auth_protocol) {
32874aea	410	pr->auth_plen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 6);
	411	pr->auth_dlen = GET_16BIT(pr->firstpkt[0], pr->firstpkt + 8);
	412	pr->auth_psize = (pr->auth_plen + 3) & ~3;
	413	pr->auth_dsize = (pr->auth_dlen + 3) & ~3;
	414	/* Leave room for a terminating zero, to make our lives easier. */
3d88e64d	415	pr->auth_protocol = snewn(pr->auth_psize + 1, char);
92d60585	416	pr->auth_data = snewn(pr->auth_dsize, unsigned char);
9c964e85	417	}
	418
	419	/*
	420	* Read the auth_protocol and auth_data strings.
	421	*/
	422	while (len > 0 && pr->data_read < 12 + pr->auth_psize)
32874aea	423	pr->auth_protocol[pr->data_read++ - 12] = (len--, *data++);
9c964e85	424	while (len > 0 && pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
32874aea	425	pr->auth_data[pr->data_read++ - 12 -
32874aea	426	pr->auth_psize] = (unsigned char) (len--, *data++);
9c964e85	427	if (pr->data_read < 12 + pr->auth_psize + pr->auth_dsize)
5471d09a	428	return 0;
9c964e85	429
	430	/*
	431	* If we haven't verified the authentication, do so now.
	432	*/
	433	if (!pr->verified) {
b3ebaa28	434	char *err;
32874aea	435
32874aea	436	pr->auth_protocol[pr->auth_plen] = '\0'; /* ASCIZ */
b3ebaa28	437	err = x11_verify(pr->peer_ip, pr->peer_port,
b3ebaa28	438	pr->auth, pr->auth_protocol,
302121de	439	pr->auth_data, pr->auth_dlen);
32874aea	440
	441	/*
	442	* If authentication failed, construct and send an error
	443	* packet, then terminate the connection.
	444	*/
b3ebaa28	445	if (err) {
	446	char *message;
	447	int msglen, msgsize;
	448	unsigned char *reply;
	449
	450	message = dupprintf("PuTTY X11 proxy: %s", err);
	451	msglen = strlen(message);
3d88e64d	452	reply = snewn(8 + msglen+1 + 4, unsigned char); /* include zero */
b3ebaa28	453	msgsize = (msglen + 3) & ~3;
32874aea	454	reply[0] = 0; /* failure */
	455	reply[1] = msglen; /* length of reason string */
	456	memcpy(reply + 2, pr->firstpkt + 2, 4); /* major/minor proto vsn */
75105663	457	PUT_16BIT(pr->firstpkt[0], reply + 6, msgsize >> 2);/* data len */
32874aea	458	memset(reply + 8, 0, msgsize);
32874aea	459	memcpy(reply + 8, message, msglen);
f28e6b7c	460	sshfwd_write(pr->c, (char *)reply, 8 + msgsize);
32874aea	461	sshfwd_close(pr->c);
32874aea	462	x11_close(s);
b3ebaa28	463	sfree(reply);
b3ebaa28	464	sfree(message);
5471d09a	465	return 0;
32874aea	466	}
	467
	468	/*
	469	* Now we know we're going to accept the connection. Strip
e0e7dff8	470	* the fake auth data, and optionally put real auth data in
e0e7dff8	471	* instead.
32874aea	472	*/
e0e7dff8	473	{
	474	char realauthdata[64];
	475	int realauthlen = 0;
	476	int authstrlen = strlen(x11_authnames[pr->auth->realproto]);
2f92b717	477	unsigned long ip;
2f92b717	478	int port;
e0e7dff8	479	static const char zeroes[4] = { 0,0,0,0 };
	480
	481	if (pr->auth->realproto == X11_MIT) {
	482	assert(pr->auth->reallen <= lenof(realauthdata));
	483	realauthlen = pr->auth->reallen;
	484	memcpy(realauthdata, pr->auth->realdata, realauthlen);
2f92b717	485	} else if (pr->auth->realproto == X11_XDM &&
	486	pr->auth->reallen == 16 &&
	487	sk_getxdmdata(s, &ip, &port)) {
	488	time_t t;
	489	realauthlen = 24;
	490	memset(realauthdata, 0, 24);
	491	memcpy(realauthdata, pr->auth->realdata, 8);
	492	PUT_32BIT_MSB_FIRST(realauthdata+8, ip);
	493	PUT_16BIT_MSB_FIRST(realauthdata+12, port);
	494	t = time(NULL);
	495	PUT_32BIT_MSB_FIRST(realauthdata+14, t);
6e7f5aee	496	des_encrypt_xdmauth(pr->auth->realdata+9,
6e7f5aee	497	(unsigned char *)realauthdata, 24);
2f92b717	498	}
e0e7dff8	499	/* implement other auth methods here if required */
	500
	501	PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 6, authstrlen);
	502	PUT_16BIT(pr->firstpkt[0], pr->firstpkt + 8, realauthlen);
	503
	504	sk_write(s, (char *)pr->firstpkt, 12);
	505
	506	if (authstrlen) {
	507	sk_write(s, x11_authnames[pr->auth->realproto], authstrlen);
	508	sk_write(s, zeroes, 3 & (-authstrlen));
	509	}
	510	if (realauthlen) {
	511	sk_write(s, realauthdata, realauthlen);
	512	sk_write(s, zeroes, 3 & (-realauthlen));
	513	}
	514	}
32874aea	515	pr->verified = 1;
9c964e85	516	}
	517
	518	/*
	519	* After initialisation, just copy data simply.
	520	*/
	521
5471d09a	522	return sk_write(s, data, len);
9c964e85	523	}