1 files changed, 97 insertions, 0 deletions
diff --git a/src/routers/rf_get_transport.c b/src/routers/rf_get_transport.c
new file mode 100644
index 0000000..2f639e0
--- /dev/null
+++ b/src/routers/rf_get_transport.c
@@ -0,0 +1,97 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) The Exim Maintainers 2021 - 2022 */
+/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+#include "rf_functions.h"
+
+
+/*************************************************
+*       Get transport for a router               *
+*************************************************/
+
+/* If transport_name contains $, it must be expanded each time and used as a
+transport name. Otherwise, look up the transport only if the destination is not
+already set.
+
+Some routers (e.g. accept) insist that their transport option is set at
+initialization time. However, for some (e.g. file_transport in redirect), there
+is no such check, because the transport may not be required. Calls to this
+function from the former type of router have require_name = NULL, because it
+will never be used. NULL is also used in verify_only cases, where a transport
+is not required.
+
+Arguments:
+  tpname        the text of the transport name
+  tpptr         where to put the transport
+  addr          the address being processed
+  router_name   for error messages
+  require_name  used in the error message if transport is unset
+
+Returns:        TRUE if *tpptr is already set and tpname has no '$' in it;
+                TRUE if a transport has been placed in tpptr;
+                FALSE if there's a problem, in which case
+                addr->message contains a message, and addr->basic_errno has
+                ERRNO_BADTRANSPORT set in it.
+*/
+
+BOOL
+rf_get_transport(uschar *tpname, transport_instance **tpptr, address_item *addr,
+  uschar *router_name, uschar *require_name)
+{
+uschar *ss;
+BOOL expandable;
+
+if (!tpname)
+  {
+  if (!require_name) return TRUE;
+  addr->basic_errno = ERRNO_BADTRANSPORT;
+  addr->message = string_sprintf("%s unset in %s router", require_name,
+    router_name);
+  return FALSE;
+  }
+
+expandable = Ustrchr(tpname, '$') != NULL;
+if (*tpptr != NULL && !expandable) return TRUE;
+
+if (expandable)
+  {
+  if (!(ss = expand_string(tpname)))
+    {
+    addr->basic_errno = ERRNO_BADTRANSPORT;
+    addr->message = string_sprintf("failed to expand transport "
+      "\"%s\" in %s router: %s", tpname, router_name, expand_string_message);
+    return FALSE;
+    }
+  if (is_tainted(ss))
+    {
+    log_write(0, LOG_MAIN|LOG_PANIC,
+      "attempt to use tainted value '%s' from '%s' for transport", ss, tpname);
+    addr->basic_errno = ERRNO_BADTRANSPORT;
+    /* Avoid leaking info to an attacker */
+    addr->message = US"internal configuration error";
+    return FALSE;
+    }
+  }
+else
+  ss = tpname;
+
+for (transport_instance * tp = transports; tp; tp = tp->next)
+  if (Ustrcmp(tp->name, ss) == 0)
+    {
+    DEBUG(D_route) debug_printf("set transport %s\n", ss);
+    *tpptr = tp;
+    return TRUE;
+    }
+
+addr->basic_errno = ERRNO_BADTRANSPORT;
+addr->message = string_sprintf("transport \"%s\" not found in %s router", ss,
+  router_name);
+return FALSE;
+}
+
+/* End of rf_get_transport.c */