From a0b0724f76eaeab561c4624d99d81f08e531a113 Mon Sep 17 00:00:00 2001
From: "Martine S. Lenders" <m.lenders@fu-berlin.de>
Date: Thu, 20 Feb 2020 16:42:19 +0100
Subject: [PATCH] examples/gnrc_border_router: add optional DHCPv6 support

---
 examples/gnrc_border_router/Kconfig   | 10 +++++++
 examples/gnrc_border_router/Makefile  | 32 ++++++++++++++++++++--
 examples/gnrc_border_router/README.md | 38 ++++++++++++++++++++++++++-
 3 files changed, 77 insertions(+), 3 deletions(-)
 create mode 100644 examples/gnrc_border_router/Kconfig

diff --git a/examples/gnrc_border_router/Kconfig b/examples/gnrc_border_router/Kconfig
new file mode 100644
index 0000000000..a45569e9a3
--- /dev/null
+++ b/examples/gnrc_border_router/Kconfig
@@ -0,0 +1,10 @@
+if MODULE_ETHOS
+config GNRC_DHCPV6_CLIENT_6LBR_STATIC_ROUTE
+    default y
+    depends on MODULE_GNRC_DHCPV6_CLIENT_6LBR && KCONFIG_MODULE_GNRC_DHCPV6
+config GNRC_NETIF_IPV6_ADDRS_NUMOF
+    # CONFIG_GNRC_DHCPV6_CLIENT_6LBR_STATIC_ROUTE=1 requires one more address
+    # for `fe80::2`.
+    default 3
+    depends on KCONFIG_MODULE_GNRC_NETIF
+endif # MODULE_ETHOS
diff --git a/examples/gnrc_border_router/Makefile b/examples/gnrc_border_router/Makefile
index 48262568e8..52581de201 100644
--- a/examples/gnrc_border_router/Makefile
+++ b/examples/gnrc_border_router/Makefile
@@ -50,8 +50,15 @@ USEMODULE += shell
 USEMODULE += shell_commands
 USEMODULE += ps
 
-# include UHCP client
-USEMODULE += gnrc_uhcpc
+USE_DHCPV6 ?= 0
+
+ifeq (1,$(USE_DHCPV6))
+  # include DHCPv6 client for 6LoWPAN border router
+  USEMODULE += gnrc_dhcpv6_client_6lbr
+else
+  # include UHCP client
+  USEMODULE += gnrc_uhcpc
+endif
 
 # Optionally include RPL as a routing protocol. When includede gnrc_uhcpc will
 # configure the node as a RPL DODAG root when receiving a prefix.
@@ -68,24 +75,45 @@ TAP ?= tap0
 IPV6_PREFIX ?= 2001:db8::/64
 
 ifeq (native,$(BOARD))
+ifneq (1,$(USE_DHCPV6))
 TERMDEPS += uhcpd-daemon
 
 .PHONY: uhcpd-daemon
 
 uhcpd-daemon: host-tools
 	$(RIOTTOOLS)/uhcpd/bin/uhcpd $(TAP) $(IPV6_PREFIX) &
+endif # USE_DHCPV6
 else
 # We override the `make term` command to use ethos
+ifeq (1,$(USE_DHCPV6))
+TERMPROG ?= sudo $(RIOTTOOLS)/ethos/ethos
+TERMFLAGS ?= $(TAP) $(PORT) $(ETHOS_BAUDRATE)
+else # USE_DHCPV6
 TERMPROG ?= sudo sh $(RIOTTOOLS)/ethos/start_network.sh
 TERMFLAGS ?= $(PORT) $(TAP) $(IPV6_PREFIX)
+endif
 
+STATIC_ROUTES ?= 1
 # We depend on the ethos host tools to run the border router, we build them
 # if necessary
 TERMDEPS += host-tools
 endif
 
+# As there is an 'Kconfig' we want to explicitly disable Kconfig by setting
+# the variable to empty
+SHOULD_RUN_KCONFIG ?=
+
 include $(RIOTBASE)/Makefile.include
 
+ifndef CONFIG_GNRC_DHCPV6_CLIENT_6LBR_STATIC_ROUTE
+ifeq (1,$(STATIC_ROUTES))
+  CFLAGS += -DCONFIG_GNRC_DHCPV6_CLIENT_6LBR_STATIC_ROUTE=1
+  # CONFIG_GNRC_DHCPV6_CLIENT_6LBR_STATIC_ROUTE=1 requires one more address for
+  # `fe80::2`.
+  CFLAGS += -DCONFIG_GNRC_NETIF_IPV6_ADDRS_NUMOF=3
+endif
+endif
+
 .PHONY: host-tools
 
 host-tools:
diff --git a/examples/gnrc_border_router/README.md b/examples/gnrc_border_router/README.md
index 30e1fe6620..1cc15dc4e9 100644
--- a/examples/gnrc_border_router/README.md
+++ b/examples/gnrc_border_router/README.md
@@ -1,6 +1,7 @@
 # gnrc_border_router using automatic configuration
 This setup uses a single serial interface, ethos (Ethernet Over Serial)
-and UHCP (micro Host Configuration Protocol).
+and UHCP (micro Host Configuration Protocol) (using DHCPv6 alternatively is also
+possible).
 Ethos multiplexes serial data to separate ethernet packets from shell commands.
 UHCP is in charge of configuring the wireless interface prefix
 and routes on the BR.
@@ -11,6 +12,34 @@ The script `start_network.sh` enables a *ready-to-use* BR in only one command.
 This functionality works only on Linux machines.
 Mac OSX support will be added in the future (lack of native `tap` interface).
 
+If you want to use DHCPv6, you also need a DHCPv6 server configured for prefix
+delegation from the interface facing the border router. With the [KEA] DHCPv6
+server e.g. you can use the following configuration:
+
+```json
+"Dhcp6":
+{
+  "interfaces-config": {
+    "interfaces": [ "tap0" ]
+  },
+  ...
+  "subnet6": [
+  {    "interface": "tap0",
+       "subnet": "2001:db8::/16",
+       "pd-pools": [ { "prefix": "2001:db8::",
+                       "prefix-len": 16,
+                       "delegated-len": 64 } ] },
+  ]
+  ...
+}
+```
+
+Note that when working with TAP interfaces you might need to restart your DHCPv6
+server once *after* you started the border router application (see below), since
+Linux might not recognize the interface as connected.
+
+[KEA]: https://kea.isc.org/
+
 ## Setup
 First, you need to compile `ethos`.
 Go to `/dist/tools/ethos` and type:
@@ -32,6 +61,13 @@ Afterwards, proceed to compile and flash `gnrc_border_router` to your board:
 make clean all flash
 ```
 
+If you want to use DHCPv6 instead of UHCP compile with the environment variable
+`USE_DHCPV6` set to 1
+
+```bash
+USE_DHCPV6=1 make clean all flash
+```
+
 ## Usage
 Start the `start_network.sh` script by doing on `dist/tools/ethos`: