Get rid of the error-return mechanism from x11_init.

Now that it doesn't actually make a network connection because that's
deferred until after the X authorisation exchange, there's no point in
having it return an error message and write the real output through a
pointer argument. Instead, we can just have it return xconn directly
and simplify the call sites.

[originally from svn r10081]

ssh.c

@@ -4887,34 +4887,22 @@ static void ssh1_smsg_x11_open(Ssh ssh, struct Packet *pktin)
 		    PKT_INT, remoteid, PKT_END);
 	logevent("Rejected X11 connect request");
     } else {
-        char *err;
-
 	c = snew(struct ssh_channel);
 	c->ssh = ssh;
 
-	if ((err = x11_init(&c->u.x11.xconn, ssh->x11authtree, c,
+	c->u.x11.xconn = x11_init(ssh->x11authtree, c, NULL, -1);
-                            NULL, -1)) != NULL) {
+        c->remoteid = remoteid;
-	    logeventf(ssh, "Opening X11 forward connection failed: %s", err);
+        c->halfopen = FALSE;
-            sfree(err);
+        c->localid = alloc_channel_id(ssh);
-	    sfree(c);
+        c->closes = 0;
-	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
+        c->pending_eof = FALSE;
-			PKT_INT, remoteid, PKT_END);
+        c->throttling_conn = 0;
-	} else {
+        c->type = CHAN_X11;	/* identify channel type */
-	    logevent
+        add234(ssh->channels, c);
-		("Opening X11 forward connection succeeded");
+        send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
-	    c->remoteid = remoteid;
+                    PKT_INT, c->remoteid, PKT_INT,
-	    c->halfopen = FALSE;
+                    c->localid, PKT_END);
-	    c->localid = alloc_channel_id(ssh);
+        logevent("Opened X11 forward channel");
-	    c->closes = 0;
-	    c->pending_eof = FALSE;
-	    c->throttling_conn = 0;
-	    c->type = CHAN_X11;	/* identify channel type */
-	    add234(ssh->channels, c);
-	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
-			PKT_INT, c->remoteid, PKT_INT,
-			c->localid, PKT_END);
-	    logevent("Opened X11 forward channel");
-	}
     }
 }
 
@@ -7563,7 +7551,6 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 
     if (typelen == 3 && !memcmp(type, "x11", 3)) {
 	char *addrstr;
-	char *x11err;
 
 	ssh_pkt_getstring(pktin, &peeraddr, &peeraddrlen);
 	addrstr = snewn(peeraddrlen+1, char);
@@ -7576,14 +7563,12 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 
 	if (!ssh->X11_fwd_enabled)
 	    error = "X11 forwarding is not enabled";
-	else if ((x11err = x11_init(&c->u.x11.xconn, ssh->x11authtree, c,
+	else {
-				    addrstr, peerport)) != NULL) {
+            c->u.x11.xconn = x11_init(ssh->x11authtree, c,
-	    logeventf(ssh, "Local X11 connection failed: %s", x11err);
+                                      addrstr, peerport);
-            sfree(x11err);
-	    error = "Unable to open an X11 connection";
-	} else {
-	    logevent("Opening X11 forward connection succeeded");
 	    c->type = CHAN_X11;
+
+            logevent("Opened X11 forward channel");
 	}
 
 	sfree(addrstr);

ssh.h

@@ -418,8 +418,7 @@ void x11_free_display(struct X11Display *disp);
 struct X11FakeAuth *x11_invent_fake_auth(tree234 *t, int authtype);
 void x11_free_fake_auth(struct X11FakeAuth *auth);
 struct X11Connection;                  /* opaque outside x11fwd.c */
-extern char *x11_init(struct X11Connection **, tree234 *authtree,
+struct X11Connection *x11_init(tree234 *authtree, void *, const char *, int);
-                      void *, const char *, int);
 extern void x11_close(struct X11Connection *);
 extern int x11_send(struct X11Connection *, char *, int);
 extern void x11_send_eof(struct X11Connection *s);

x11fwd.c

@@ -649,14 +649,11 @@ int x11_get_screen_number(char *display)
 }
 
 /*
- * Called to set up the raw connection.
+ * Called to set up the X11Connection structure, though this does not
- * 
+ * yet connect to an actual server.
- * On success, returns NULL and fills in *xconnret. On error, returns
- * a dynamically allocated error message string.
  */
-extern char *x11_init(struct X11Connection **xconnret,
+struct X11Connection *x11_init(tree234 *authtree, void *c,
-                      tree234 *authtree, void *c,
+                               const char *peeraddr, int peerport)
-                      const char *peeraddr, int peerport)
 {
     static const struct plug_function_table fn_table = {
 	x11_log,
@@ -671,7 +668,7 @@ extern char *x11_init(struct X11Connection **xconnret,
     /*
      * Open socket.
      */
-    xconn = *xconnret = snew(struct X11Connection);
+    xconn = snew(struct X11Connection);
     xconn->fn = &fn_table;
     xconn->auth_protocol = NULL;
     xconn->authtree = authtree;
@@ -698,7 +695,7 @@ extern char *x11_init(struct X11Connection **xconnret,
     xconn->peer_addr = peeraddr ? dupstr(peeraddr) : NULL;
     xconn->peer_port = peerport;
 
-    return NULL;
+    return xconn;
 }
 
 void x11_close(struct X11Connection *xconn)