[PATCH v4 00/14] Introduce the lwIP network stack

Fri Jun 21 18:08:17 CEST 2024

On Fri, Jun 21, 2024 at 5:59 AM Jerome Forissier
<jerome.forissier at linaro.org> wrote:
>
>
>
> On 6/20/24 19:10, Tim Harvey wrote:
> > On Mon, Jun 17, 2024 at 8:33 AM Jerome Forissier
> > <jerome.forissier at linaro.org> wrote:
> >>
> >> This is a rework of a patch series by Maxim Uvarov: "net/lwip: add lwip
> >> library for the network stack" [1]. The goal is to introduce the lwIP TCP/IP
> >> stack [2] [3] as an alternative to the current implementation in net/,
> >> selectable with Kconfig, and ultimately keep only lwIP if possible. Some
> >> reasons for doing so are:
> >> - Make the support of HTTPS in the wget command easier. Javier T. (CC'd)
> >> has some additional lwIP and Mbed TLS patches to do so. With that it
> >> becomes possible to fetch and launch a distro installer such as Debian
> >> etc. using a secure, authenticated connection directly from the U-Boot
> >> shell. Several use cases:
> >>   * Authentication: prevent MITM attack (third party replacing the
> >> binary with a different one)
> >>   * Confidentiality: prevent third parties from grabbing a copy of the
> >> image as it is being downloaded
> >>   * Allow connection to servers that do not support plain HTTP anymore
> >> (this is becoming more and more common on the Internet these days)
> >> - Possibly benefit from additional features implemented in lwIP
> >> - Less code to maintain in U-Boot
> >>
> >> Prior to applying this series, the lwIP stack needs to be added as a
> >> Git subtree with the following command:
> >>
> >>  $  git subtree add --squash --prefix lib/lwip/lwip https://git.savannah.gnu.org/git/lwip.git STABLE-2_2_0_RELEASE
> >>
> >> The first patch renames some enums in order to avoid a conflict when a
> >> later patch enables the lwIP library.
> >>
> >> The second patch introduces a new Kconfig symbol: NET_LWIP, which selects
> >> the lwIP implementation instead of the current one (NET). Contrary to the
> >> approach chosen by Maxim in [1], NET_LWIP and NET cannot be enabled
> >> simultaneously. The rationale is we want to start from a clean state and
> >> not pull potentially duplicated functionality from both stacks. Note
> >> however that a few files are still built in net/, they are the ones
> >> related to ethernet device management and the ethernet bootflow.
> >>
> >> The third patch splits the net.h header into net-legacy.h, net-common.h,
> >> net-lwip.h, leaving net.h as a simple wrapper.
> >>
> >> The fourth patch introduces the Makefile to build lwIP when NET_LWIP is
> >> enabled.
> >>
> >> The subsequent patches implement various network-oriented commands and
> >> features: dhcp, dns, ping, tftpboot, wget.
> >>
> >> A number of features are currently incompatible with NET_LWIP: SANDBOX,
> >> DFU_TFTP, FASTBOOT, SPL_NET. All make assumptions on how the network
> >> stack is implemented and/or pull sybols that are not trivially exported
> >> from lwIP. Some interface rework may be needed.
> >>
> >> Due to the above and in order to provide some level of testing, a new QEMU
> >> configuration is introduced (qemu_arm64_lwip_defconfig) which is the same
> >> as qemu_arm64_defconfig but with NET_LWIP and CMD_*_LWIP enabled.
> >> Tests are added to test/py/tests/test_net.py for that configuration.
> >>
> >
> > Hi Jermone,
> >
> > I've given this a spin on an imx8mm-venice-gw73xx-0x via
> > imx8mm_venice_defconfig and I can't get DHCP to work (didn't work in
> > v3 either):
> >
> > $ diff defconfig configs/imx8mm_venice_defconfig
> > 68,69c68,71
> > < CONFIG_CMD_DNS_LWIP=y
> > < CONFIG_CMD_WGET_LWIP=y
> > ---
> >> CONFIG_CMD_DHCP6=y
> >> CONFIG_CMD_TFTPPUT=y
> >> CONFIG_SYS_DISABLE_AUTOLOAD=y
> >> CONFIG_CMD_WGET=y
> > 88,90c90,94
> > < CONFIG_NET_LWIP=y
> > < CONFIG_LWIP_DEBUG=y
> > < CONFIG_LWIP_ASSERT=y
> > ---
> >> CONFIG_NET_RANDOM_ETHADDR=y
> >> CONFIG_IP_DEFRAG=y
> >> CONFIG_TFTP_BLOCKSIZE=4096
> >> CONFIG_PROT_TCP_SACK=y
> >> CONFIG_IPV6=y
> >
> > Target:
> > u-boot=> net list
> > eth0 : ethernet at 30be0000 00:d0:12:b5:f8:41 active
> > u-boot=> dhcp || echo fail
> > eth0: ethernet at 30be0000 00:d0:12:b5:f8:41 active
> > netif_set_ipaddr: netif address being changed
> > netif: added interface 0 addr 192.168.1.1 netmask 0.0.0.0 gw 0.0.0.0
> > etharp_request: sending ARP request.
> > etharp_raw: sending raw ARP packet.
> > ethernet_output: sending packet 000000007df00bf0
> > dhcp_start(netif=000000007df2af40) 0dhcp_start(): mallocing new DHCP client
> > dhcp_start(): allocated dhcp
> > dhcp_start(): starting DHCP configuration
> > dhcp_discover()
> > transaction id xid(42021)
> > dhcp_discover: making request
> > dhcp_discover: sendto(DISCOVER, IP_ADDR_BROADCAST, LWIP_IANA_PORT_DHCP_SERVER)
> > ip4_output_if: 0IP header:
> > +-------------------------------+
> > | 4 | 5 |  0x00 |       336     | (v, hl, tos, len)
> > +-------------------------------+
> > |        0      |000|       0   | (id, flags, offset)
> > +-------------------------------+
> > |  255  |   17  |    0xba9d     | (ttl, proto, chksum)
> > +-------------------------------+
> > |    0  |    0  |    0  |    0  | (src)
> > +-------------------------------+
> > |  255  |  255  |  255  |  255  | (dest)
> > +-------------------------------+
> > ip4_output_if: call netif->output()
> > ethernet_output: sending packet 000000007df2c010
> > dhcp_discover: deleting()
> > dhcp_discover: SELECTING
> > dhcp_discover(): set request timeout 2000 msecs
> > ethernet_input: dest:ff:ff:ff:ff:ff:ff, src:28:28:5d:bb:16:9f, type:8899
> > ethernet_input: dest:ff:ff:ff:ff:ff:ff, src:00:27:0e:0d:74:ba, type:806
> > etharp_update_arp_entry: 172.24.20.24 - 00:27:0e:0d:74:ba
> > etharp_find_entry: found empty entry 0
> > etharp_find_entry: no empty entry found and not allowed to recycle
> > etharp_input: incoming ARP request
> > etharp_input: ARP request was not for us.
> > ethernet_input: dest:ff:ff:ff:ff:ff:ff, src:98:90:96:ac:d7:63, type:806
> > etharp_update_arp_entry: 172.24.20.3 - 98:90:96:ac:d7:63
> > etharp_find_entry: found empty entry 0
> > etharp_find_entry: no empty entry found and not allowed to recycle
> > etharp_input: incoming ARP request
> > etharp_input: ARP request was not for us.
> > ethernet_input: dest:ff:ff:ff:ff:ff:ff, src:84:2b:2b:4e:5a:9a, type:806
> > etharp_update_arp_entry: 172.24.0.1 - 84:2b:2b:4e:5a:9a
> > etharp_find_entry: found empty entry 0
> > etharp_find_entry: no empty entry found and not allowed to recycle
> > etharp_input: incoming ARP request
> > etharp_input: ARP request was not for us.
> > ethernet_input: dest:ff:ff:ff:ff:ff:ff, src:cc:96:e5:1e:a0:7b, type:800
> > ip_input: iphdr->dest 0xffff1fac netif->ip_addr 0x101a8c0 (0x0, 0x0, 0xffff1fac)
> > ip4_input: UDP packet to DHCP client port 138
> > ip4_input: packet not for us.
>
> That's weird. I think what could happen is the interface already has
> a static IP assigned when it is registered to the lwIP stack and thus
> DHCP never receives the packed because it is dropped before.
> I have reworked the initialization code in v5, lwIP will get to know
> only one interface at a time and I make sure that interface is registered
> without an IP address when doing DHCP. Hopefully that should fix the issue.
>
> Thanks for testing!
>

I tried your to-upstream/v5-wip branch
(042bea36eb9731079a3d7afffe3774d79e06ac5d) and it behaves the same. Do
you have something else to try/test?

Best Regards,

Tim