#include <stdio.h>#include <stdlib.h>#include "putty.h"#include "ssh.h"#ifndef FALSE#define FALSE 0#endif#ifndef TRUE#define TRUE 1#endif#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] = (value), \  (cp)[1] = (value) >> 8, \  (cp)[2] = (value) >> 16, \  (cp)[3] = (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] = (value), \  (cp)[1] = (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] = (value) >> 24, \  (cp)[1] = (value) >> 16, \  (cp)[2] = (value) >> 8, \  (cp)[3] = (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] = (value) >> 8, \  (cp)[1] = (value) )struct PFwdPrivate {    const struct plug_function_table *fn;    /* the above variable absolutely *must* be the first in this structure */    void *c;			       /* (channel) data used by ssh.c */    void *backhandle;		       /* instance of SSH backend itself */    /* Note that backhandle need not be filled in if c is non-NULL */    Socket s;    int throttled, throttle_override;    int ready;    /*     * `dynamic' does double duty. It's set to 0 for an ordinary     * forwarded port, and nonzero for SOCKS-style dynamic port     * forwarding; but it also represents the state of the SOCKS     * exchange.     */    int dynamic;    /*     * `hostname' and `port' are the real hostname and port, once     * we know what we're connecting to; they're unused for this     * purpose while conducting a local SOCKS exchange, which means     * we can also use them as a buffer and pointer for reading     * data from the SOCKS client.     */    char hostname[256+8];    int port;    /*     * When doing dynamic port forwarding, we can receive     * connection data before we are actually able to send it; so     * we may have to temporarily hold some in a dynamically     * allocated buffer here.     */    void *buffer;    int buflen;};static int pfd_closing(Plug plug, const char *error_msg, int error_code,		       int calling_back){    struct PFwdPrivate *pr = (struct PFwdPrivate *) 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.     */    if (pr->c)	sshfwd_close(pr->c);    pfd_close(pr->s);    return 1;}static int pfd_receive(Plug plug, int urgent, char *data, int len){    struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;    if (pr->dynamic) {	while (len--) {	    /*	     * Throughout SOCKS negotiation, "hostname" is re-used as a	     * random protocol buffer with "port" storing the length.	     */ 	    if (pr->port >= lenof(pr->hostname)) {		/* Request too long. */		if ((pr->dynamic >> 12) == 4) {		    /* Send back a SOCKS 4 error before closing. */		    char data[8];		    memset(data, 0, sizeof(data));		    data[1] = 91;      /* generic `request rejected' */		    sk_write(pr->s, data, 8);		}		pfd_close(pr->s);		return 1;	    }	    pr->hostname[pr->port++] = *data++;	    /*	     * Now check what's in the buffer to see if it's a	     * valid and complete message in the SOCKS exchange.	     */	    if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&		pr->hostname[0] == 4) {		/*		 * SOCKS 4.		 */		if (pr->dynamic == 1)		    pr->dynamic = 0x4000;		if (pr->port < 2) continue;/* don't have command code yet */		if (pr->hostname[1] != 1) {		    /* Not CONNECT. */		    /* Send back a SOCKS 4 error before closing. */		    char data[8];		    memset(data, 0, sizeof(data));		    data[1] = 91;      /* generic `request rejected' */		    sk_write(pr->s, data, 8);		    pfd_close(pr->s);		    return 1;		}		if (pr->port <= 8) continue; /* haven't started user/hostname */		if (pr->hostname[pr->port-1] != 0)		    continue;	       /* haven't _finished_ user/hostname */		/*		 * Now we have a full SOCKS 4 request. Check it to		 * see if it's a SOCKS 4A request.		 */		if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&		    pr->hostname[6] == 0 && pr->hostname[7] != 0) {		    /*		     * It's SOCKS 4A. So if we haven't yet		     * collected the host name, we should continue		     * waiting for data in order to do so; if we		     * have, we can go ahead.		     */		    int len;		    if (pr->dynamic == 0x4000) {			pr->dynamic = 0x4001;			pr->port = 8;      /* reset buffer to overwrite name */			continue;		    }		    pr->hostname[0] = 0;   /* reply version code */		    pr->hostname[1] = 90;   /* request granted */		    sk_write(pr->s, pr->hostname, 8);		    len= pr->port - 8;		    pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);		    memmove(pr->hostname, pr->hostname + 8, len);		    goto connect;		} else {		    /*		     * It's SOCKS 4, which means we should format		     * the IP address into the hostname string and		     * then just go.		     */		    pr->hostname[0] = 0;   /* reply version code */		    pr->hostname[1] = 90;   /* request granted */		    sk_write(pr->s, pr->hostname, 8);		    pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);		    sprintf(pr->hostname, "%d.%d.%d.%d",			    (unsigned char)pr->hostname[4],			    (unsigned char)pr->hostname[5],			    (unsigned char)pr->hostname[6],			    (unsigned char)pr->hostname[7]);		    goto connect;		}	    }	    if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&		pr->hostname[0] == 5) {		/*		 * SOCKS 5.		 */		if (pr->dynamic == 1)		    pr->dynamic = 0x5000;		if (pr->dynamic == 0x5000) {		    int i, method;		    char data[2];		    /*		     * We're receiving a set of method identifiers.		     */		    if (pr->port < 2) continue;/* no method count yet */		    if (pr->port < 2 + (unsigned char)pr->hostname[1])			continue;      /* no methods yet */		    method = 0xFF;     /* invalid */		    for (i = 0; i < (unsigned char)pr->hostname[1]; i++)			if (pr->hostname[2+i] == 0) {			    method = 0;/* no auth */			    break;			}		    data[0] = 5;		    data[1] = method;		    sk_write(pr->s, data, 2);		    pr->dynamic = 0x5001;		    pr->port = 0;      /* re-empty the buffer */		    continue;		}		if (pr->dynamic == 0x5001) {		    /*		     * We're receiving a SOCKS request.		     */		    unsigned char reply[10]; /* SOCKS5 atyp=1 reply */		    int atype, alen = 0;		    /*		     * Pre-fill reply packet.		     * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0		     * (atyp=1) in the reply; if we succeed, we don't know		     * the right answers, and if we fail, they should be		     * ignored.		     */		    memset(reply, 0, lenof(reply));		    reply[0] = 5; /* VER */		    reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */		    if (pr->port < 6) continue;		    atype = (unsigned char)pr->hostname[3];		    if (atype == 1)    /* IPv4 address */			alen = 4;		    if (atype == 4)    /* IPv6 address */			alen = 16;		    if (atype == 3)    /* domain name has leading length */			alen = 1 + (unsigned char)pr->hostname[4];		    if (pr->port < 6 + alen) continue;		    if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {			/* Not CONNECT or reserved field nonzero - error */			reply[1] = 1;	/* generic failure */			sk_write(pr->s, (char *) reply, lenof(reply));			pfd_close(pr->s);			return 1;		    }		    /*		     * Now we have a viable connect request. Switch		     * on atype.		     */		    pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);		    if (atype == 1) {			/* REP=0 (success) already */			sk_write(pr->s, (char *) reply, lenof(reply));			sprintf(pr->hostname, "%d.%d.%d.%d",				(unsigned char)pr->hostname[4],				(unsigned char)pr->hostname[5],				(unsigned char)pr->hostname[6],				(unsigned char)pr->hostname[7]);			goto connect;		    } else if (atype == 3) {			/* REP=0 (success) already */			sk_write(pr->s, (char *) reply, lenof(reply));			memmove(pr->hostname, pr->hostname + 5, alen-1);			pr->hostname[alen-1] = '\0';			goto connect;		    } else {			/*			 * Unknown address type. (FIXME: support IPv6!)			 */			reply[1] = 8;	/* atype not supported */			sk_write(pr->s, (char *) reply, lenof(reply));			pfd_close(pr->s);			return 1;		    }		}	    }	    /*	     * If we get here without either having done `continue'	     * or `goto connect', it must be because there is no	     * sensible interpretation of what's in our buffer. So	     * close the connection rudely.	     */	    pfd_close(pr->s);	    return 1;	}	return 1;	/*	 * We come here when we're ready to make an actual	 * connection.	 */	connect:	pr->c = new_sock_channel(pr->backhandle, pr->s);	if (pr->c == NULL) {	    pfd_close(pr->s);	    return 1;	} else {	    /* asks to forward to the specified host/port for this */	    ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");	}	pr->dynamic = 0;	/*	 * Now freeze the socket until the SSH server confirms the	 * connection.	 */	sk_set_frozen(pr->s, 1);	/*	 * If there's any data remaining in our current buffer,	 * save it to be sent on pfd_confirm().	 */	if (len > 0) {	    pr->buffer = snewn(len, char);	    memcpy(pr->buffer, data, len);	    pr->buflen = len;	}    }    if (pr->ready) {	if (sshfwd_write(pr->c, data, len) > 0) {	    pr->throttled = 1;	    sk_set_frozen(pr->s, 1);	}    }    return 1;}static void pfd_sent(Plug plug, int bufsize){    struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;    if (pr->c)	sshfwd_unthrottle(pr->c, bufsize);}/* * Called when receiving a PORT OPEN from the server */const char *pfd_newconnect(Socket *s, char *hostname, int port,			   void *c, const Config *cfg){    static const struct plug_function_table fn_table = {	pfd_closing,	pfd_receive,	pfd_sent,	NULL    };    SockAddr addr;    const char *err;    char *dummy_realhost;    struct PFwdPrivate *pr;    /*     * Try to find host.     */    addr = name_lookup(hostname, port, &dummy_realhost, cfg);    if ((err = sk_addr_error(addr)) != NULL) {	sk_addr_free(addr);	return err;    }    /*     * Open socket.     */    pr = snew(struct PFwdPrivate);    pr->buffer = NULL;    pr->fn = &fn_table;    pr->throttled = pr->throttle_override = 0;    pr->ready = 1;    pr->c = c;    pr->backhandle = NULL;	       /* we shouldn't need this */    pr->dynamic = 0;    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;    }    sk_set_private_ptr(*s, pr);    return NULL;}/* called when someone connects to the local port */static int pfd_accepting(Plug p, OSSocket sock){    static const struct plug_function_table fn_table = {	pfd_closing,	pfd_receive,	pfd_sent,	NULL    };    struct PFwdPrivate *pr, *org;    Socket s;    const char *err;    org = (struct PFwdPrivate *)p;    pr = snew(struct PFwdPrivate);    pr->buffer = NULL;    pr->fn = &fn_table;    pr->c = NULL;    pr->backhandle = org->backhandle;    pr->s = s = sk_register(sock, (Plug) pr);    if ((err = sk_socket_error(s)) != NULL) {	sfree(pr);	return err != NULL;    }    sk_set_private_ptr(s, pr);    pr->throttled = pr->throttle_override = 0;    pr->ready = 0;    if (org->dynamic) {	pr->dynamic = 1;	pr->port = 0;		       /* "hostname" buffer is so far empty */	sk_set_frozen(s, 0);	       /* we want to receive SOCKS _now_! */    } else {	pr->dynamic = 0;	strcpy(pr->hostname, org->hostname);	pr->port = org->port;		pr->c = new_sock_channel(org->backhandle, s);	if (pr->c == NULL) {	    sfree(pr);	    return 1;	} else {	    /* asks to forward to the specified host/port for this */	    ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");	}    }    return 0;}/* Add a new forwarding from port -> desthost:destport sets up a listener on the local machine on (srcaddr:)port */const char *pfd_addforward(char *desthost, int destport, char *srcaddr,			   int port, void *backhandle, const Config *cfg){    static const struct plug_function_table fn_table = {	pfd_closing,	pfd_receive,		       /* should not happen... */	pfd_sent,		       /* also should not happen */	pfd_accepting    };    const char *err;    struct PFwdPrivate *pr;    Socket s;    /*     * Open socket.     */    pr = snew(struct PFwdPrivate);    pr->buffer = NULL;    pr->fn = &fn_table;    pr->c = NULL;    if (desthost) {	strcpy(pr->hostname, desthost);	pr->port = destport;	pr->dynamic = 0;    } else	pr->dynamic = 1;    pr->throttled = pr->throttle_override = 0;    pr->ready = 0;    pr->backhandle = backhandle;    pr->s = s = new_listener(srcaddr, port, (Plug) pr,			     !cfg->lport_acceptall, cfg);    if ((err = sk_socket_error(s)) != NULL) {	sfree(pr);	return err;    }    sk_set_private_ptr(s, pr);    return NULL;}void pfd_close(Socket s){    struct PFwdPrivate *pr;    if (!s)	return;    pr = (struct PFwdPrivate *) sk_get_private_ptr(s);    sfree(pr->buffer);    sfree(pr);    sk_close(s);}void pfd_unthrottle(Socket s){    struct PFwdPrivate *pr;    if (!s)	return;    pr = (struct PFwdPrivate *) sk_get_private_ptr(s);    pr->throttled = 0;    sk_set_frozen(s, pr->throttled || pr->throttle_override);}void pfd_override_throttle(Socket s, int enable){    struct PFwdPrivate *pr;    if (!s)	return;    pr = (struct PFwdPrivate *) 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 pfd_send(Socket s, char *data, int len){    if (s == NULL)	return 0;    return sk_write(s, data, len);}void pfd_confirm(Socket s){    struct PFwdPrivate *pr;    if (s == NULL)	return;    pr = (struct PFwdPrivate *) sk_get_private_ptr(s);    pr->ready = 1;    sk_set_frozen(s, 0);    sk_write(s, NULL, 0);    if (pr->buffer) {	sshfwd_write(pr->c, pr->buffer, pr->buflen);	sfree(pr->buffer);	pr->buffer = NULL;    }}