* src/gateway.c (check_string_l): New function.

(check_string): New function.
(make_gateway_address): New function.

Rev: src/gateway.c:1.3

src/gateway.c

@@ -22,6 +22,13 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include "gateway.h"
+
+#include "format.h"
+#include "io.h"
+
+#include "gateway.c.x"
+
 /* A gateway is a mechanism to delegate some channels to a separate
  * process. The main lsh process opens a unix domain socket, and other
  * processes can connect and read and write cleartext ssh packets.
@@ -30,6 +37,62 @@
  * delegated and can be read from the gateway. */
 
 
+/* The gateway socket is named "TMP/x-lsh-USER/HOST%REMOTE-USER".
+ *
+ * The choice of the '%' separator in the socket name makes sure we
+ * don't collide with any valid dns names, or with literal IPv4 or IPv6
+ * addresses. And it should be really rare in usernames. */
+
+static int
+check_string_l(unsigned length, const UINT8 *s)
+{
+  unsigned i;
+  for (i = 0; i<length; i++)
+    switch(*s++)
+      {
+      case  '\0':
+      case '%':
+      case '/':
+	return 0;
+      default:
+	break;
+      }
+  return 1;
+}
+
+static int
+check_string(const UINT8 *s)
+{
+  for (;;)
+    switch(*s++)
+      {
+      case  '\0':
+	return 1;
+      case '%':
+      case '/':
+	return 0;
+      default:
+	break;
+      }
+}
+
+struct local_info *
+make_gateway_address(char *local_user, char *remote_user,
+		     struct address_info *target)
+{
+  char *tmp = getenv("TMPDIR");
+  if (!tmp)
+    tmp = "/tmp";
+  
+  if (check_string(local_user)
+      && check_string(remote_user)
+      && check_string_l(target->ip->length, target->ip->data))
+    return make_local_info(ssh_cformat("%lz/x-lsh-%lz", tmp, local_user),
+			   ssh_cformat("%lS:%lz", target->ip, remote_user));
+  else
+    return NULL;
+}
+
 /* Keeps track of one connection to the gateway. */
 
 /* GABA: