Allowed optimized exporting of a subprefix tree

Added an option for export filter to allow for prefiltering based on the
prefix. Routes outside the given prefix are completely ignored. Config
is simple:

	export in <net> <filter>;

1 files changed, 6 insertions, 0 deletions

diff --git a/proto/pipe/config.Y b/proto/pipe/config.Y
index c869de9f..0990168e 100644
--- a/proto/pipe/config.Y
+++ b/proto/pipe/config.Y
@@ -41,6 +41,12 @@ pipe_proto:
    pipe_proto_start '{'
  | pipe_proto proto_item ';'
  | pipe_proto channel_item_ ';'
+ | pipe_proto IMPORT IN net_any imexport ';' {
+    if (this_channel->net_type && ($4->type != this_channel->net_type))
+      cf_error("Incompatible export prefilter type");
+    PIPE_CFG->in_subprefix = $4;
+    this_channel->in_filter = $5;
+  }
  | pipe_proto PEER TABLE rtable ';' { PIPE_CFG->peer = $4; }
  | pipe_proto MAX GENERATION expr ';' {
     if (($4 < 1) || ($4 > 254)) cf_error("Max generation must be in range 1..254, got %u", $4);