Tayga configuration can be generated.

This facilitates more configuration being authoritatively
in `rc.conf`.

defaults/rc.conf

@@ -56,4 +56,44 @@ allow_hosts_rules="${rc_router_gen_dir}/pf.rules.conf"
 
 rtsold_flags="-F"
 
+###################
+## Tayga options ##
+###################
+tayga_enable="NO"
+tayga_config="${rc_router_gen_dir}/tayga.conf"
+tayga_device="nat64"
+
+# The Tayga defaults for 6to4 make a few weird
+# assumptions -- you're okay with using 6to4 space
+# and you do not explicitly enable Class E on FreeBSD
+# Otherwise `240.0.0.0/8` makes a heck of a lot more sense.
+
+# For Tayga, we use the old 6to4 space.
+# It's mostly unused these days, and it's a similar purpose
+tayga_ipv4_addr="192.88.99.1"
+tayga_ipv4_endpoint="192.88.99.129"
+
+# For Tayga, we use the lower half of the 6to4 space for the
+# 6to4 space as the pool.
+tayga_ipv4_net="192.88.99.0/25"
+
+# This variable can be set to a list of prefixes that get directed to
+# Tayga for routing.  This is exceptionally useful to redirect v4
+# addresses to v6-only hosts, thus simplifying the v4 compat story
+# for v6-only hosts.  Instead of dual stack throughout, just route
+# v4 addresses and ranges for "pseudo-dual-stack" hosts here.
+# This is especially useful to conserve and publish personal v4 public
+# allocations.  The first and last of any range can be used, thus
+# reclaiming much of your limited v4 space utility.
+tayga_v4_prefixes=""
+
+tayga_group="internal group tayga"
+
+# We claim the address right after the end of the 32-bit slice.
+# A different addrss could be taken, but this seemed somewhat safe.
+tayga_ipv6_endpoint="64:ff9b::1:0:0"
+tayga_ipv6_net="64:ff9b::/96" # The default NAT64 prefix
+
+tayga_data_dir="/var/db/tayga"
+
 # vim: ft=bash

rc.d/generate_tayga

@@ -0,0 +1,48 @@
+#!/bin/sh
+#
+# PROVIDE: generate_tayga
+# REQUIRE: netif
+# BEFORE: tayga
+# KEYWORD: shutdown
+#
+
+. ${RC_ROUTER_HARNESS}/etc/rc.subr
+
+name='generate_tayga'
+
+start_cmd='generate_tayga_start'
+stop_cmd='generate_tayga_stop'
+rcvar='generate_tayga_enable'
+
+load_rc_config 'generate_tayga'
+
+generate_tayga_start()
+{
+	gen_tayga_dir=${rc_router_gen_dir}
+	tayga_conf=${gen_tayga_dir}/tayga.conf
+	cat ${rc_router_dir}/templates/tayga.conf \
+		| sed \
+			-e "s;@TAYGA_DEVICE@;${tayga_device};" \
+			-e "s;@TAYGA_IPV4_ADDR@;${tayga_ipv4_addr};" \
+			-e "s;@TAYGA_IPV6_ENDPOINT@;${tayga_ipv6_endpoint};" \
+			-e "s;@TAYGA_IPV6_NET@;${tayga_ipv6_net};" \
+			-e "s;@TAYGA_IPV4_NET@;${tayga_ipv4_net};" \
+			-e "s;@TAYGA_DATA_DIR@;${tayga_data_dir};" \
+		> ${tayga_conf}
+
+	for mapping in ${tayga_mappings}
+	do
+		echo "map ${mapping}" | sed -e 's/->/ /' >> ${tayga_conf}
+	done
+}
+
+generate_tayga_stop()
+{
+	true
+}
+
+################ Epilogue
+
+run_rc_command "$1"
+
+# vim: ft=bash

rc.subr

@@ -650,6 +650,11 @@ load_isp_hints()
 	done
 }
 
+add_tayga_map()
+{
+	tayga_mappings="${tayga_mappings} ${1}->${2}"
+}
+
 _rc_router_epilogue()
 {
 	rtsold_flags="${rtsold_flags} ${ipv6_isp_interfaces}"

templates/tayga.conf

@@ -0,0 +1,14 @@
+tun-device @TAYGA_DEVICE@
+
+ipv4-addr @TAYGA_IPV4_ADDR@
+
+ipv6-addr @TAYGA_IPV6_ENDPOINT@
+
+prefix @TAYGA_IPV6_NET@
+
+dynamic-pool @TAYGA_IPV4_NET@
+
+data-dir @TAYGA_DATA_DIR@
+
+
+# Maps (These get set via `tayga_map` command):