X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/6ee9b735013c0e636b027b77e9f6ba57a96e142f..HEAD:/portfwd.c

diff --git a/portfwd.c b/portfwd.c
index dd8e6550..00cff5ee 100644
--- a/portfwd.c
+++ b/portfwd.c
@@ -1,3 +1,7 @@
+/*
+ * SSH port forwarding.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -11,86 +15,329 @@
 #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 pfwd_queue {
-    struct pfwd_queue *next;
-    char *buf;
-};
-
 struct PFwdPrivate {
-    struct plug_function_table *fn;
+    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;
-    char hostname[128];
     int throttled, throttle_override;
-    int port;
     int ready;
-    struct pfwd_queue *waiting;
+    /*
+     * `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.
+     */
+    char *hostname;
+    int port;
+    /*
+     * `socksbuf' is the buffer we use to accumulate a SOCKS request.
+     */
+    char *socksbuf;
+    int sockslen, sockssize;
+    /*
+     * 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;
 };
 
-void pfd_close(Socket s);
+static struct PFwdPrivate *new_portfwd_private(void)
+{
+    struct PFwdPrivate *pr = snew(struct PFwdPrivate);
+    pr->hostname = NULL;
+    pr->socksbuf = NULL;
+    pr->sockslen = pr->sockssize = 0;
+    pr->buffer = NULL;
+    return pr;
+}
+
+static void free_portfwd_private(struct PFwdPrivate *pr)
+{
+    if (!pr)
+        return;
+    sfree(pr->hostname);
+    sfree(pr->socksbuf);
+    sfree(pr->buffer);
+    sfree(pr);
+}
 
+static void pfd_log(Plug plug, int type, SockAddr addr, int port,
+		    const char *error_msg, int error_code)
+{
+    /* we have to dump these since we have no interface to logging.c */
+}
 
-static int pfd_closing(Plug plug, char *error_msg, int error_code,
+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.
-     */
-    sshfwd_close(pr->c);
-    pfd_close(pr->s);
+    if (error_msg) {
+        /*
+         * Socket error. Slam the connection instantly shut.
+         */
+        if (pr->c) {
+            sshfwd_unclean_close(pr->c);
+        } else {
+            /*
+             * We might not have an SSH channel, if a socket error
+             * occurred during SOCKS negotiation. If not, we must
+             * clean ourself up without sshfwd_unclean_close's call
+             * back to pfd_close.
+             */
+            pfd_close(pr->s);
+        }
+    } else {
+        /*
+         * Ordinary EOF received on socket. Send an EOF on the SSH
+         * channel.
+         */
+        if (pr->c)
+            sshfwd_write_eof(pr->c);
+    }
+
     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--) {
+	    if (pr->sockslen >= pr->sockssize) {
+                pr->sockssize = pr->sockslen * 5 / 4 + 256;
+                pr->socksbuf = sresize(pr->socksbuf, pr->sockssize, char);
+	    }
+	    pr->socksbuf[pr->sockslen++] = *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->socksbuf[0] == 4) {
+		/*
+		 * SOCKS 4.
+		 */
+		if (pr->dynamic == 1)
+		    pr->dynamic = 0x4000;
+		if (pr->sockslen < 2)
+                    continue;        /* don't have command code yet */
+		if (pr->socksbuf[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->sockslen <= 8)
+                    continue;      /* haven't started user/hostname */
+		if (pr->socksbuf[pr->sockslen-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->socksbuf[4] == 0 && pr->socksbuf[5] == 0 &&
+		    pr->socksbuf[6] == 0 && pr->socksbuf[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->sockslen = 8; /* reset buffer to overwrite name */
+			continue;
+		    }
+		    pr->socksbuf[0] = 0;   /* reply version code */
+		    pr->socksbuf[1] = 90;   /* request granted */
+		    sk_write(pr->s, pr->socksbuf, 8);
+		    len = pr->sockslen - 8;
+		    pr->port = GET_16BIT_MSB_FIRST(pr->socksbuf+2);
+                    pr->hostname = snewn(len+1, char);
+                    pr->hostname[len] = '\0';
+		    memcpy(pr->hostname, pr->socksbuf + 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->socksbuf[0] = 0;   /* reply version code */
+		    pr->socksbuf[1] = 90;   /* request granted */
+		    sk_write(pr->s, pr->socksbuf, 8);
+		    pr->port = GET_16BIT_MSB_FIRST(pr->socksbuf+2);
+		    pr->hostname = dupprintf("%d.%d.%d.%d",
+                                             (unsigned char)pr->socksbuf[4],
+                                             (unsigned char)pr->socksbuf[5],
+                                             (unsigned char)pr->socksbuf[6],
+                                             (unsigned char)pr->socksbuf[7]);
+		    goto connect;
+		}
+	    }
+
+	    if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
+		pr->socksbuf[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->sockslen < 2)
+                        continue;      /* no method count yet */
+		    if (pr->sockslen < 2 + (unsigned char)pr->socksbuf[1])
+			continue;      /* no methods yet */
+		    method = 0xFF;     /* invalid */
+		    for (i = 0; i < (unsigned char)pr->socksbuf[1]; i++)
+			if (pr->socksbuf[2+i] == 0) {
+			    method = 0;/* no auth */
+			    break;
+			}
+		    data[0] = 5;
+		    data[1] = method;
+		    sk_write(pr->s, data, 2);
+		    pr->dynamic = 0x5001;
+		    pr->sockslen = 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->sockslen < 6) continue;
+		    atype = (unsigned char)pr->socksbuf[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->socksbuf[4];
+		    if (pr->sockslen < 6 + alen) continue;
+		    if (pr->socksbuf[1] != 1 || pr->socksbuf[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->socksbuf+4+alen);
+		    if (atype == 1) {
+			/* REP=0 (success) already */
+			sk_write(pr->s, (char *) reply, lenof(reply));
+			pr->hostname = dupprintf("%d.%d.%d.%d",
+                                                 (unsigned char)pr->socksbuf[4],
+                                                 (unsigned char)pr->socksbuf[5],
+                                                 (unsigned char)pr->socksbuf[6],
+                                                 (unsigned char)pr->socksbuf[7]);
+			goto connect;
+		    } else if (atype == 3) {
+			/* REP=0 (success) already */
+			sk_write(pr->s, (char *) reply, lenof(reply));
+                        pr->hostname = snewn(alen, char);
+			pr->hostname[alen-1] = '\0';
+			memcpy(pr->hostname, pr->socksbuf + 5, alen-1);
+			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:
+        sfree(pr->socksbuf);
+        pr->socksbuf = NULL;
+
+	/*
+	 * Freeze the socket until the SSH server confirms the
+	 * connection.
+	 */
+	sk_set_frozen(pr->s, 1);
+
+	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;
+
+	/*
+	 * 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;
@@ -104,15 +351,18 @@ static void pfd_sent(Plug plug, int bufsize)
 {
     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
 
-    sshfwd_unthrottle(pr->c, bufsize);
+    if (pr->c)
+	sshfwd_unthrottle(pr->c, bufsize);
 }
 
 /*
  * Called when receiving a PORT OPEN from the server
  */
-char *pfd_newconnect(Socket *s, char *hostname, int port, void *c)
+const char *pfd_newconnect(Socket *s, char *hostname, int port,
+			   void *c, Conf *conf, int addressfamily)
 {
-    static struct plug_function_table fn_table = {
+    static const struct plug_function_table fn_table = {
+	pfd_log,
 	pfd_closing,
 	pfd_receive,
 	pfd_sent,
@@ -120,34 +370,40 @@ char *pfd_newconnect(Socket *s, char *hostname, int port, void *c)
     };
 
     SockAddr addr;
-    char *err, *dummy_realhost;
+    const char *err;
+    char *dummy_realhost;
     struct PFwdPrivate *pr;
 
     /*
      * Try to find host.
      */
-    addr = sk_namelookup(hostname, &dummy_realhost);
-    if ((err = sk_addr_error(addr)))
+    addr = name_lookup(hostname, port, &dummy_realhost, conf, addressfamily);
+    if ((err = sk_addr_error(addr)) != NULL) {
+	sk_addr_free(addr);
+        sfree(dummy_realhost);
 	return err;
+    }
 
     /*
      * Open socket.
      */
-    pr = (struct PFwdPrivate *) smalloc(sizeof(struct PFwdPrivate));
+    pr = new_portfwd_private();
     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, (Plug) pr);
-    if ((err = sk_socket_error(*s))) {
-	sfree(pr);
+    pr->s = *s = new_connection(addr, dummy_realhost, port,
+				0, 1, 0, 0, (Plug) pr, conf);
+    sfree(dummy_realhost);
+    if ((err = sk_socket_error(*s)) != NULL) {
+	free_portfwd_private(pr);
 	return err;
     }
 
     sk_set_private_ptr(*s, pr);
-    sk_addr_free(addr);
     return NULL;
 }
 
@@ -155,9 +411,10 @@ char *pfd_newconnect(Socket *s, char *hostname, int port, void *c)
  called when someone connects to the local port
  */
 
-static int pfd_accepting(Plug p, void *sock)
+static int pfd_accepting(Plug p, OSSocket sock)
 {
-    static struct plug_function_table fn_table = {
+    static const struct plug_function_table fn_table = {
+	pfd_log,
 	pfd_closing,
 	pfd_receive,
 	pfd_sent,
@@ -165,37 +422,43 @@ static int pfd_accepting(Plug p, void *sock)
     };
     struct PFwdPrivate *pr, *org;
     Socket s;
-    char *err;
+    const char *err;
 
     org = (struct PFwdPrivate *)p;
-    pr = (struct PFwdPrivate *) smalloc(sizeof(struct PFwdPrivate));
+    pr = new_portfwd_private();
     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))) {
-	sfree(pr);
+    if ((err = sk_socket_error(s)) != NULL) {
+	free_portfwd_private(pr);
 	return err != NULL;
     }
 
-    pr->c = new_sock_channel(org->backhandle, s);
+    sk_set_private_ptr(s, pr);
 
-    strcpy(pr->hostname, org->hostname);
-    pr->port = org->port;
     pr->throttled = pr->throttle_override = 0;
     pr->ready = 0;
-    pr->waiting = NULL;
-
-    sk_set_private_ptr(s, pr);
 
-    if (pr->c == NULL) {
-	sfree(pr);
-	return 1;
+    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 {
-	/* asks to forward to the specified host/port for this */
-	ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
+	pr->dynamic = 0;
+	pr->hostname = dupstr(org->hostname);
+	pr->port = org->port;	
+	pr->c = new_sock_channel(org->backhandle, s);
+
+	if (pr->c == NULL) {
+	    free_portfwd_private(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;
@@ -205,41 +468,50 @@ static int pfd_accepting(Plug p, void *sock)
 /* Add a new forwarding from port -> desthost:destport
  sets up a listener on the local machine on (srcaddr:)port
  */
-char *pfd_addforward(char *desthost, int destport, char *srcaddr, int port,
-		     void *backhandle)
+const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
+			   int port, void *backhandle, Conf *conf,
+			   void **sockdata, int address_family)
 {
-    static struct plug_function_table fn_table = {
+    static const struct plug_function_table fn_table = {
+	pfd_log,
 	pfd_closing,
 	pfd_receive,		       /* should not happen... */
 	pfd_sent,		       /* also should not happen */
 	pfd_accepting
     };
 
-    char *err;
+    const char *err;
     struct PFwdPrivate *pr;
     Socket s;
 
     /*
      * Open socket.
      */
-    pr = (struct PFwdPrivate *) smalloc(sizeof(struct PFwdPrivate));
+    pr = new_portfwd_private();
     pr->fn = &fn_table;
     pr->c = NULL;
-    strcpy(pr->hostname, desthost);
-    pr->port = destport;
+    if (desthost) {
+	pr->hostname = dupstr(desthost);
+	pr->port = destport;
+	pr->dynamic = 0;
+    } else
+	pr->dynamic = 1;
     pr->throttled = pr->throttle_override = 0;
     pr->ready = 0;
-    pr->waiting = NULL;
     pr->backhandle = backhandle;
 
-    pr->s = s = new_listener(srcaddr, port, (Plug) pr, !cfg.lport_acceptall);
-    if ((err = sk_socket_error(s))) {
-	sfree(pr);
+    pr->s = s = new_listener(srcaddr, port, (Plug) pr,
+			     !conf_get_int(conf, CONF_lport_acceptall),
+			     conf, address_family);
+    if ((err = sk_socket_error(s)) != NULL) {
+	free_portfwd_private(pr);
 	return err;
     }
 
     sk_set_private_ptr(s, pr);
 
+    *sockdata = (void *)s;
+
     return NULL;
 }
 
@@ -252,11 +524,19 @@ void pfd_close(Socket s)
 
     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 
-    sfree(pr);
+    free_portfwd_private(pr);
 
     sk_close(s);
 }
 
+/*
+ * Terminate a listener.
+ */
+void pfd_terminate(void *sv)
+{
+    pfd_close((Socket)sv);
+}
+
 void pfd_unthrottle(Socket s)
 {
     struct PFwdPrivate *pr;
@@ -289,6 +569,10 @@ int pfd_send(Socket s, char *data, int len)
     return sk_write(s, data, len);
 }
 
+void pfd_send_eof(Socket s)
+{
+    sk_write_eof(s);
+}
 
 void pfd_confirm(Socket s)
 {
@@ -301,4 +585,9 @@ void pfd_confirm(Socket 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;
+    }
 }