test/lwip: enabling both, IPv4 and IPv6, results in unexpected behavior #18097
Description
Description
When enabling IPv4 and IPv6 for the lwip test application, some values will default to IPv6.
For example, the formatting of IP addresses will always expect IPv6 addresses and a socket will default to IPv6.
One reason is that in common.h you find
#if IS_USED(MODULE_LWIP_IPV6)
#include "net/ipv6.h"
#define SOCK_IP_EP_ANY SOCK_IPV6_EP_ANY
#elif IS_USED(MODULE_LWIP_IPV4)
#include "net/ipv4.h"
#define SOCK_IP_EP_ANY SOCK_IPV4_EP_ANY
#endif Hence, SOCK_IP_EP_ANY is set to IPv6 only.
An interesting observation that may lead to an actual bug in the network stack is that IPv4 datagrams are received on the IPv6 only socket nevertheless.
Steps to reproduce the issue
Build the lwip test application with LWIP_IPV4=1.
Add something like
#define _TEST_ADDR4_LOCAL (0x974fa8c0U) /* 192.168.79.150 */
#define _TEST_ADDR4_MASK (0x00ffffffU) /* 255.255.255.0 */
sys_lock_tcpip_core();
struct netif *iface = netif_find("ET0");
ip4_addr_t ip, subnet;
ip.addr = _TEST_ADDR4_LOCAL;
subnet.addr = _TEST_ADDR4_MASK;
netif_set_addr(iface, &ip, &subnet, NULL);
sys_unlock_tcpip_core();at the beginning of the main function and add something like
sock_udp_send(sock, sock_inbuf, res, &src);to the _udp_recv() function to echo the received datagram.
Build the application on native and assign a matching IPv4 address to the bridge, e.g.,
sudo ip a a 192.168.79.151/24 dev tapbr0
Start the application, start a UDP server and use netcat to send anything to the server.
Expected results
In netcat one should the sent packet echoed and in the RIOT shell one should see the IPv4 address (e.g., 192.168.79.151) of the sender.
Actual results
The echo fails and an IPv6 formatted address is printed.
Versions
Test on RIOT 2022.04.
Should be irrelenvant but in any case:
Operating System Environment
----------------------------
Operating System: "Arch Linux"
Kernel: Linux 5.17.5-arch1-1 x86_64 unknown
System shell: GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)
make's shell: GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu)
Installed compiler toolchains
-----------------------------
native gcc: gcc (GCC) 11.2.0
arm-none-eabi-gcc: arm-none-eabi-gcc (Arch Repository) 12.1.0
avr-gcc: missing
mips-mti-elf-gcc: missing
msp430-elf-gcc: missing
riscv-none-elf-gcc: missing
riscv64-unknown-elf-gcc: missing
riscv-none-embed-gcc: missing
xtensa-esp32-elf-gcc: missing
xtensa-esp8266-elf-gcc: missing
clang: clang version 13.0.1
Installed compiler libs
-----------------------
arm-none-eabi-newlib: "4.2.0"
mips-mti-elf-newlib: missing
msp430-elf-newlib: missing
riscv-none-elf-newlib: missing
riscv64-unknown-elf-newlib: missing
riscv-none-embed-newlib: missing
xtensa-esp32-elf-newlib: missing
xtensa-esp8266-elf-newlib: missing
avr-libc: missing (missing)
Installed development tools
---------------------------
ccache: ccache version 4.6
cmake: cmake version 3.23.1
cppcheck: missing
doxygen: missing
git: git version 2.36.1
make: GNU Make 4.3
openocd: Open On-Chip Debugger 0.11.0
python: Python 3.10.4
python2: Python 2.7.18
python3: Python 3.10.4
flake8: error: /usr/bin/python3: No module named flake8
coccinelle: missing