Add Kconfig symbol LWIP_ICMP_SHOW_UNREACH which, when enabled, prints a
message to the console upon reception of ICMP unreachable messages. For
example:
$ make qemu_arm64_lwip_defconfig
$ qemu-system-aarch64 -M virt -cpu max -nographic -bios u-boot.bin
[...]
=> dhcp
DHCP client bound to address 10.0.2.15 (0 ms)
=> tftp 192.168.0.100:69:Image
Using virtio-net#32 device
TFTP from server 192.168.0.100; our IP address is 10.0.2.15
Filename 'Image'.
Load address: 0x40200000
Loading: ICMP destination unreachable (host unreachable) from 192.168.0.16
Timeout!
=> tftp 192.168.0.16:69:Image
Using virtio-net#32 device
TFTP from server 192.168.0.16; our IP address is 10.0.2.15
Filename 'Image'.
Load address: 0x40200000
Loading: ICMP destination unreachable (port unreachable) from 192.168.0.16
Timeout!
=>
Signed-off-by: Jerome Forissier <jerome.foriss...@linaro.org>
---
lib/lwip/u-boot/arch/cc.h | 7 +++++++
lib/lwip/u-boot/lwipopts.h | 4 ++++
net/lwip/Kconfig | 13 +++++++++++++
net/lwip/Makefile | 1 +
net/lwip/icmp_unreach.c | 38 ++++++++++++++++++++++++++++++++++++++
5 files changed, 63 insertions(+)
create mode 100644 net/lwip/icmp_unreach.c
diff --git a/lib/lwip/u-boot/arch/cc.h b/lib/lwip/u-boot/arch/cc.h
index 04ab94d6b70..849c79c5a8d 100644
--- a/lib/lwip/u-boot/arch/cc.h
+++ b/lib/lwip/u-boot/arch/cc.h
@@ -56,4 +56,11 @@ static inline const char *sntp_format_time(time_t t)
}
#define sntp_format_time sntp_format_time
+
+#ifdef CONFIG_LWIP_ICMP_SHOW_UNREACH
+struct pbuf;
+void net_lwip_icmp_dest_unreach(int code, struct pbuf *p);
+
+#define ICMP_DEST_UNREACH_CB(_c, _p) net_lwip_icmp_dest_unreach(_c, _p)
+#endif
#endif /* LWIP_ARCH_CC_H */
diff --git a/lib/lwip/u-boot/lwipopts.h b/lib/lwip/u-boot/lwipopts.h
index 46af91f9410..80b93ea172d 100644
--- a/lib/lwip/u-boot/lwipopts.h
+++ b/lib/lwip/u-boot/lwipopts.h
@@ -80,7 +80,11 @@
#define IP_DEFAULT_TTL 255
+#if defined(CONFIG_PROT_ICMP_LWIP)
+#define LWIP_ICMP 1
+#else
#define LWIP_ICMP 0
+#endif
#if defined(CONFIG_PROT_RAW_LWIP)
#define LWIP_RAW 1
diff --git a/net/lwip/Kconfig b/net/lwip/Kconfig
index d28a8a7df94..5789766fe62 100644
--- a/net/lwip/Kconfig
+++ b/net/lwip/Kconfig
@@ -4,6 +4,16 @@
if NET_LWIP
+config LWIP_ICMP_SHOW_UNREACH
+ bool "Print ICMP Destination Unreachable messages"
+ default y
+ depends on CMD_TFTPBOOT || CMD_SNTP
+ select PROT_ICMP_LWIP
+ help
+ Prints a message whenever an ICMP Destination Unreachable message is
+ received while running a network command that sends requests via UDP.
+ Enabling this can make troubleshooting easier.
+
config LWIP_DEBUG
bool "Enable debug traces in the lwIP library"
help
@@ -31,6 +41,9 @@ config PROT_DNS_LWIP
bool
select PROT_UDP_LWIP
+config PROT_ICMP_LWIP
+ bool
+
config PROT_RAW_LWIP
bool
diff --git a/net/lwip/Makefile b/net/lwip/Makefile
index 97299d9b542..09c3b3511a4 100644
--- a/net/lwip/Makefile
+++ b/net/lwip/Makefile
@@ -2,6 +2,7 @@ ccflags-y += -I$(srctree)/lib/lwip/lwip/src/include
-I$(srctree)/lib/lwip/u-boot
obj-$(CONFIG_$(PHASE_)DM_ETH) += net-lwip.o
obj-$(CONFIG_CMD_DHCP) += dhcp.o
+obj-$(CONFIG_LWIP_ICMP_SHOW_UNREACH) += icmp_unreach.o
obj-$(CONFIG_CMD_TFTPBOOT) += tftp.o
obj-$(CONFIG_WGET) += wget.o
diff --git a/net/lwip/icmp_unreach.c b/net/lwip/icmp_unreach.c
new file mode 100644
index 00000000000..9e8a05f5717
--- /dev/null
+++ b/net/lwip/icmp_unreach.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* Copyright (C) 2025 Linaro Ltd. */
+
+#include <lwip/icmp.h>
+#include <lwip/ip4_addr.h>
+#include <lwip/pbuf.h>
+#include <lwip/prot/ip4.h>
+
+static const char *code_to_str(int code)
+{
+ switch (code) {
+ case ICMP_DUR_NET:
+ return "network unreachable";
+ case ICMP_DUR_HOST:
+ return "host unreachable";
+ case ICMP_DUR_PROTO:
+ return "protocol unreachable";
+ case ICMP_DUR_PORT:
+ return "port unreachable";
+ case ICMP_DUR_FRAG:
+ return "fragmentation needed and DF set";
+ case ICMP_DUR_SR:
+ return "source route failed";
+ default:
+ break;
+ }
+ return "unknown cause";
+}
+
+void net_lwip_icmp_dest_unreach(int code, struct pbuf *p)
+{
+ struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
+ ip4_addr_t src;
+
+ ip4_addr_copy(src, iphdr->src);
+ printf("ICMP destination unreachable (%s) from %s\n",
+ code_to_str(code), ip4addr_ntoa(&src));
+}
--
2.43.0
