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Allow a single DHCP configuration via the system configuration submenu

PATCH Superseded Jérémy Rosen 4 participants 11 messages Jan 16, 2015 – Feb 16, 2015

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Jérémy Rosen

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#0 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

This patch allows the setup of simple a single interface to be automatically brought up and configured via DHCP on system startup.

The interface name can be set via a configuration option. This patch does not support systemd-networkd, any complex network configuration should be done via overlay of /etc/network/interfaces or the relevant networkd configuration file

Signed-off-by J?r?my Rosen <[email protected]>

---
v4 : - changed condition to also depend on ifupdown or busybox
suggestion by Gustavo Zacarias

v3 : - move the condition from shell logic to make logic
(reusing the code proposed by Thomas Petazzoni)

v2 : - inline shell section instead of providing a script
- add one Config.in option instead of two

---
 system/Config.in                       | 21 +++++++++++++++++++++
 system/skeleton/etc/network/interfaces |  4 ----
 system/system.mk                       | 25 +++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 4 deletions(-)
 delete mode 100644 system/skeleton/etc/network/interfaces
system/Config.in +21 -0
index 4d7a4e3..71d8689 100644
@@ -324,6 +324,27 @@ config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW
 
 endif # BR2_ROOTFS_SKELETON_DEFAULT
 
+
+config BR2_SIMPLE_DHCP
+	string "Name of the physical network interface to run DHCP on"
+	default ""
+	depends on !BR2_PACKAGE_SYSTEMD_NETWORKD && (BR2_PACKAGE_BUSYBOX || BR2_PACKAGE_IFUPDOWN)
+	help
+	  The name of the network interface to configure automatically.
+	  A DHCP request will automatically happen on startup on the selected
+	  interface.
+
+	  If left empty, no automatic DHCP requests will take place.
+
+	  For more complicated network setups use an overlay to overwrite
+	  /etc/network/interfaces or add a networkd configuration file.
+
+comment "automatic network configuration via DHCP is not compatible with networkd"
+	depends on BR2_PACKAGE_SYSTEMD_NETWORKD
+
+comment "automatic network configuration via DHCP needs ifupdown or busybox"
+	depends on !(BR2_PACKAGE_BUSYBOX || BR2_PACKAGE_IFUPDOWN)
+
 config BR2_TARGET_TZ_INFO
 	bool "Install timezone info"
 	# No timezone for musl; only for uClibc or (e)glibc.
system/skeleton/etc/network/interfaces deleted +0 -4
deleted file mode 100644
index 218b82c..0000000
@@ -1,4 +0,0 @@
-# Configure Loopback
-auto lo
-iface lo inet loopback
-
system/system.mk +25 -0
index e4a3160..96aa342 100644
@@ -38,6 +38,31 @@ ifneq ($(TARGET_GENERIC_ROOT_PASSWD),)
 TARGETS += host-mkpasswd
 endif
 
+define SET_NETWORK_LOCALHOST
+        echo "# interface file auto-generated by buildroot" >  $(TARGET_DIR)/etc/network/interfaces
+        echo                                                >> $(TARGET_DIR)/etc/network/interfaces
+        echo "auto lo"                                      >> $(TARGET_DIR)/etc/network/interfaces
+        echo "iface lo inet loopback"                       >> $(TARGET_DIR)/etc/network/interfaces
+        echo                                                >> $(TARGET_DIR)/etc/network/interfaces
+endef
+
+NETWORK_DHCP_IFACE = $(call qstrip,$(BR2_SIMPLE_DHCP))
+
+ifneq ($(NETWORK_DHCP_IFACE),)
+define SET_NETWORK_DHCP
+        echo "auto $(NETWORK_DHCP_IFACE)"                   >> $(TARGET_DIR)/etc/network/interfaces
+        echo "iface $(NETWORK_DHCP_IFACE) inet dhcp"        >> $(TARGET_DIR)/etc/network/interfaces
+endef
+endif
+
+define SET_NETWORK
+        mkdir -p $(TARGET_DIR)/etc/network/
+        $(SET_NETWORK_LOCALHOST)
+        $(SET_NETWORK_DHCP)
+endef
+
+TARGET_FINALIZE_HOOKS += SET_NETWORK
+
 ifeq ($(BR2_ROOTFS_SKELETON_DEFAULT),y)
 
 define SYSTEM_ROOT_PASSWD
Signature · 1 line
2.1.4
#1 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Dear J?r?my Rosen,

Quoted 9 lines · J?r?my Rosen
system/Config.in +9 -0
+config BR2_SIMPLE_DHCP
+	string "Name of the physical network interface to run DHCP on"
+	default ""
+	depends on !BR2_PACKAGE_SYSTEMD_NETWORKD && (BR2_PACKAGE_BUSYBOX || BR2_PACKAGE_IFUPDOWN)
+	help
+	  The name of the network interface to configure automatically.
+	  A DHCP request will automatically happen on startup on the selected
+	  interface.
+

system/Config.in config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW · line 346

Quoted 10 lines
system/Config.in +10 -0
+	  If left empty, no automatic DHCP requests will take place.
+
+	  For more complicated network setups use an overlay to overwrite
+	  /etc/network/interfaces or add a networkd configuration file.
+
+comment "automatic network configuration via DHCP is not compatible with networkd"
+	depends on BR2_PACKAGE_SYSTEMD_NETWORKD
+
+comment "automatic network configuration via DHCP needs ifupdown or busybox"
+	depends on !(BR2_PACKAGE_BUSYBOX || BR2_PACKAGE_IFUPDOWN)

I'm still not really happy with this. It's
really /etc/network/interfaces as a whole that doesn't make sense in a context where you don't have Busybox ifupdown, or the full blown ifupdown, no? Not just the DHCP part of it.

Thomas

Signature · 3 lines
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
author
#2 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Quoted 25 lines

Dear J?r?my Rosen,

Quoted 21 lines · J?r?my Rosen
system/Config.in +4 -0
+config BR2_SIMPLE_DHCP
+	string "Name of the physical network interface to run DHCP on"
+	default ""
+	depends on !BR2_PACKAGE_SYSTEMD_NETWORKD && (BR2_PACKAGE_BUSYBOX

|| BR2_PACKAGE_IFUPDOWN)

system/Config.in +3 -0
+	help
+	  The name of the network interface to configure automatically.
+	  A DHCP request will automatically happen on startup on the

selected

system/Config.in +8 -0
+	  interface.
+
+	  If left empty, no automatic DHCP requests will take place.
+
+	  For more complicated network setups use an overlay to overwrite
+	  /etc/network/interfaces or add a networkd configuration file.
+
+comment "automatic network configuration via DHCP is not

compatible with networkd"

system/Config.in +3 -0
+	depends on BR2_PACKAGE_SYSTEMD_NETWORKD
+
+comment "automatic network configuration via DHCP needs ifupdown
Quoted 9 lines

system/Config.in config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW · line 346

Quoted 2 lines

or busybox"

system/Config.in +1 -0
+	depends on !(BR2_PACKAGE_BUSYBOX || BR2_PACKAGE_IFUPDOWN)

I'm still not really happy with this. It's
really /etc/network/interfaces as a whole that doesn't make sense in a
context where you don't have Busybox ifupdown, or the full blown ifupdown, no? Not just the DHCP part of it.

i'm not sure how you want me to correct that...

* not generate network/interfaces at all if ifupdown is not available
* correct the comment sections "generation of /etc/network/interfaces needs ifupdown" (but that does not reflect what the option is when it is available)
* something else

please tell me and i'll send a new patch

Quoted 6 lines

Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

#3 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

In reply to Jérémy Rosen
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line

"J?r?my" == J?r?my Rosen <[email protected]> writes:

Hi,

Quoted 8 lines

This patch allows the setup of simple a single interface to be automatically brought up and configured via DHCP on system startup.

The interface name can be set via a configuration option. This patch does not support systemd-networkd, any complex network configuration should be done via overlay of /etc/network/interfaces or the relevant networkd configuration file

Quoted 5 lines
Signed-off-by J?r?my Rosen <[email protected]>

---
v4 : - changed condition to also depend on ifupdown or busybox
suggestion by Gustavo Zacarias

Sorry for the slow response. We have discussed this during the dev days and agreed to include it. Committed with some changes, see below.

Thanks!

Quoted 1 line

+config BR2_SIMPLE_DHCP

We're not completely consist with this, but the new system options are called BR2_SYSTEM_*, so I've renamed to the option.

system/Config.in config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW · line 329

Quoted 1 line
system/Config.in +1 -0
+	string "Name of the physical network interface to run DHCP on"

This is quite long, so I reworded it to:

"Network interface to configure through DHCP"

system/Config.in config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW · line 335

Quoted 6 lines
system/Config.in +6 -0
+	default ""
+	depends on !BR2_PACKAGE_SYSTEMD_NETWORKD && (BR2_PACKAGE_BUSYBOX || BR2_PACKAGE_IFUPDOWN)
+	help
+	  The name of the network interface to configure automatically.
+	  A DHCP request will automatically happen on startup on the selected
+	  interface.

And here I reworded it a bit and mentioned an example (eth0).

system/system.mk ifneq ($(TARGET_GENERIC_ROOT_PASSWD),) · line 47

Quoted 7 lines
system/system.mk +7 -0
+define SET_NETWORK_LOCALHOST
+        echo "# interface file auto-generated by buildroot" >  $(TARGET_DIR)/etc/network/interfaces
+        echo                                                >> $(TARGET_DIR)/etc/network/interfaces
+        echo "auto lo"                                      >> $(TARGET_DIR)/etc/network/interfaces
+        echo "iface lo inet loopback"                       >> $(TARGET_DIR)/etc/network/interfaces
+        echo                                                >> $(TARGET_DIR)/etc/network/interfaces
+endef

Elsewhere in BR we use syntax like:

( \
echo foo ; \
echo bar ; \
) > file

Which is a bit less verbose, so I've changed it to that.

Signature · 1 line
Bye, Peter Korsgaard
author
#4 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Quoted 7 lines

Sorry for the slow response. We have discussed this during the dev days
and agreed to include it. Committed with some changes, see below.

Thanks!

Thanks a lot, really appreciated :)

Quoted 50 lines
Quoted 2 lines

+config BR2_SIMPLE_DHCP

We're not completely consist with this, but the new system options are
called BR2_SYSTEM_*, so I've renamed to the option.

system/Config.in config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW · line 329

Quoted 1 line
system/Config.in +1 -0
+	string "Name of the physical network interface to run DHCP on"

This is quite long, so I reworded it to:

"Network interface to configure through DHCP"

system/Config.in config BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW · line 335

Quoted 8 lines
(quoted diff) +2 -0
+	default ""
+	depends on !BR2_PACKAGE_SYSTEMD_NETWORKD && (BR2_PACKAGE_BUSYBOX

|| BR2_PACKAGE_IFUPDOWN)

system/Config.in +3 -0
+	help
+	  The name of the network interface to configure automatically.
+	  A DHCP request will automatically happen on startup on the

selected

system/Config.in +1 -0
+	  interface.

And here I reworded it a bit and mentioned an example (eth0).

Quoted 4 lines
(quoted diff) +3 -0
+define SET_NETWORK_LOCALHOST
+        echo "# interface file auto-generated by buildroot" >
 $(TARGET_DIR)/etc/network/interfaces
+        echo                                                >>
Quoted 8 lines

$(TARGET_DIR)/etc/network/interfaces
+ echo "auto lo" >>
$(TARGET_DIR)/etc/network/interfaces
+ echo "iface lo inet loopback" >>
$(TARGET_DIR)/etc/network/interfaces
+ echo >>
$(TARGET_DIR)/etc/network/interfaces
+endef

Elsewhere in BR we use syntax like:

( \
echo foo ; \
echo bar ; \
) > file

Which is a bit less verbose, so I've changed it to that.

--
Bye, Peter Korsgaard

#5 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Quoted 7 lines
Quoted 7 lines
Quoted 2 lines

+config BR2_SIMPLE_DHCP

We're not completely consist with this, but the new system options are
called BR2_SYSTEM_*, so I've renamed to the option.

On this topic, what about the following idea?

If the interface name is blank do not perform DHCP as currently If the interface name is "*" then run something like this script to automatically find and use the first network interface for DHCP I'd like to be able to use the same BR config on slightly different boards that may sometimes have different network interface names/orders The kernel handles that OK with modules so maybe buildroot could to?

Steve

#!/bin/bash
interfaces="/tmp/interfaces" # The on-the-fly generated interfaces file # This is only used for the BR2_SYSTEM_DHCP "simple single interface dhcp" option. # Many systems only have a single network interface, so auto-find/use it by default. # If there are in fact multiple network interfaces the first non-loop interface

# listed in /sys/class/net will be used as the default DHCP configured interface.
# As an aid to debugging on new systems all other interfaces found are added to the
# generated $interfaces file with DHCP enabled but only the first one is brought up.
# Run "ifup -a -i $interfaces" as an alternate to the default /etc/network/interfaces
#
if [ $# -gt 0 ]; then # be our own mapping script
	echo "default" # will always be the first interface
	exit 0
fi

first=""
echo "# Auto-generated by $(readlink -f $0)" > $interfaces
echo "auto lo" >> $interfaces
echo "iface lo inet loopback" >> $interfaces
echo "" >> $interfaces
for interface in $(ls --hide=lo* /sys/class/net); do

	if [ "$first" == "" ]; then
		first=$interface
		echo "auto $first" >>			$interfaces
	else
# This is only used to help troubleshoot any additional network interfaces later on
		echo "iface $interface inet dhcp" >>	$interfaces
	fi
	echo "" >>					$interfaces
done
# This is the only network interface that needs to be brought up for the simple case
# The mapping to default instead of using the physical inteface name is intentional
# so that all modifications and documentation will refer to the constant name "default"
echo "iface default inet dhcp" >>			$interfaces
echo "" >>						$interfaces
# Map the first physical network interface to the logical default interface
echo "mapping $first" >>				$interfaces
echo "	script $(readlink -f $0)" >>			$interfaces
# We don't need any map statements since it's always going to be "default"
#6 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Quoted 9 lines
Quoted 9 lines
Quoted 9 lines
Quoted 4 lines
Quoted 1 line

"Steve" == Steve Kenton <[email protected]> writes:

+config BR2_SIMPLE_DHCP

We're not completely consist with this, but the new system options are
called BR2_SYSTEM_*, so I've renamed to the option.

Quoted 8 lines

On this topic, what about the following idea?

If the interface name is blank do not perform DHCP as currently If the interface name is "*" then run something like this script to automatically find and use the first network interface for DHCP I'd like to be able to use the same BR config on slightly different boards that may sometimes have different network interface names/orders The kernel handles that OK with modules so maybe buildroot could to?

So those boards have network interfaces not using eth%d names? That sounds pretty uncommon to me. Another approach would simply be add an init script to rename those to eth0 with nameif.

Signature · 1 line
Bye, Peter Korsgaard
#7 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Quoted 17 lines · Peter Korsgaard
Quoted 8 lines
Quoted 8 lines
Quoted 8 lines
Quoted 3 lines
Quoted 1 line

"Steve" == Steve Kenton<[email protected]> writes:

+config BR2_SIMPLE_DHCP

We're not completely consist with this, but the new system options are
called BR2_SYSTEM_*, so I've renamed to the option.

Quoted 8 lines

On this topic, what about the following idea?

If the interface name is blank do not perform DHCP as currently If the interface name is "*" then run something like this script to automatically find and use the first network interface for DHCP I'd like to be able to use the same BR config on slightly different boards that may sometimes have different network interface names/orders The kernel handles that OK with modules so maybe buildroot could to?

Quoted 3 lines

So those boards have network interfaces not using eth%d names? That sounds pretty uncommon to me. Another approach would simply be add an init script to rename those to eth0 with nameif.

Yes, two I have to test right now are an Asrock and an ECS mini-ITX and on both
the kernel built with buildroot 2015.02-rc1 calls the network interface "sit0"

Given that the name(s) are available why not just use it/them instead of requiring the
entering of a configuration value for an interface name to use BR2_SIMPLE_DHCP?

Steve

Quoted 1 line
#8 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line

"Steve" == Steve Kenton <[email protected]> writes:

Hi,

Quoted 8 lines
Quoted 3 lines

So those boards have network interfaces not using eth%d names? That sounds pretty uncommon to me. Another approach would simply be add an init script to rename those to eth0 with nameif.

Yes, two I have to test right now are an Asrock and an ECS mini-ITX and on both
the kernel built with buildroot 2015.02-rc1 calls the network interface "sit0"

Really? sit%d is normally for point-to-point tunnels, not for real hw devices:

http://www.deepspace6.net/docs/iproute2tunnel-en.html

Signature · 1 line
Bye, Peter Korsgaard
#9 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

Quoted 13 lines · Peter Korsgaard
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line

"Steve" == Steve Kenton <[email protected]> writes:

Hi,

Quoted 8 lines
Quoted 3 lines

So those boards have network interfaces not using eth%d names? That sounds pretty uncommon to me. Another approach would simply be add an init script to rename those to eth0 with nameif.

Yes, two I have to test right now are an Asrock and an ECS mini-ITX and on both
the kernel built with buildroot 2015.02-rc1 calls the network interface "sit0"

Quoted 5 lines

Really? sit%d is normally for point-to-point tunnels, not for real hw devices:

http://www.deepspace6.net/docs/iproute2tunnel-en.html

I was not aware of that, but it certainly set off alarm bells in my mind. I'm just now getting to the networking and I thought my problem was the names being wrong. I guess I wrote a clever script to solve a problem that does not exist :-)

I don't know where "sit0" comes from but I see I'm missing a driver for my ethernet - oops! I didn't look closely enough and just assumed they were the same two devices.

Sorry for the noise.

Steve

Here is what buildroot-2015.02-rc2 shows me with lspci -k and ifconfig -a:

03:00.0 Class 0200: 10ec:8168

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

sit0 Link encap:IPv6-in-IPv4
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

And here is what Ubuntu 14.04 on the same hardware show me:

03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
Subsystem: ASRock Incorporation Motherboard (one of many)
Kernel driver in use: r8169

eth1 Link encap:Ethernet HWaddr bc:5f:f4:cb:1e:f6
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::be5f:f4ff:fecb:1ef6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1288 errors:0 dropped:0 overruns:0 frame:0 TX packets:783 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000
RX bytes:1472508 (1.4 MB) TX bytes:67242 (67.2 KB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:286 errors:0 dropped:0 overruns:0 frame:0 TX packets:286 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0
RX bytes:23049 (23.0 KB) TX bytes:23049 (23.0 KB)

author
#10 lore raw

PATCH v4 1/1 Allow a single DHCP configuration via the system configuration submenu

In reply to Peter Korsgaard

----- Mail original -----

Quoted 22 lines
Quoted 12 lines
Quoted 10 lines
Quoted 10 lines
Quoted 4 lines
Quoted 1 line

"Steve" == Steve Kenton <[email protected]> writes:

+config BR2_SIMPLE_DHCP

We're not completely consist with this, but the new system options
are
called BR2_SYSTEM_*, so I've renamed to the option.

On this topic, what about the following idea?

Quoted 9 lines

If the interface name is blank do not perform DHCP as currently If the interface name is "*" then run something like this script to automatically find and use the first network interface for DHCP I'd like to be able to use the same BR config on slightly different
boards that may sometimes have different network interface names/orders
The kernel handles that OK with modules so maybe buildroot could to?

Quoted 4 lines

So those boards have network interfaces not using eth%d names? That sounds pretty uncommon to me. Another approach would simply be add an init script to rename those to eth0 with nameif.

there is the (still pretty uncommon) case of networkd that does interface naming based on the physical layout and not the module loading order

interfaces are never named eth* in that case.

Regards

Jeremy Rosen