[PATCH] net: introduce CONFIG_DNS
Jerome Forissier
jerome.forissier at linaro.org
Fri Jul 18 12:48:48 CEST 2025
Introduce the DNS Kconfig symbol so that various network commands may
use host names without the dns command (CMD_DNS) being selected.
Signed-off-by: Jerome Forissier <jerome.forissier at linaro.org>
CC: E Shattow <e at freeshell.de>
---
cmd/Kconfig | 2 +-
cmd/lwip/dns.c | 108 ---------------------------------------
doc/usage/cmd/sntp.rst | 8 +--
doc/usage/cmd/wget.rst | 2 +-
include/net-legacy.h | 2 +-
net/Kconfig | 8 ++-
net/Makefile | 2 +-
net/lwip/Makefile | 1 +
net/lwip/dns.c | 113 +++++++++++++++++++++++++++++++++++++++++
net/lwip/net-lwip.c | 6 +--
net/net.c | 10 ++--
net/wget.c | 2 +-
12 files changed, 138 insertions(+), 126 deletions(-)
create mode 100644 net/lwip/dns.c
diff --git a/cmd/Kconfig b/cmd/Kconfig
index b3b5be1ea79..7a9c4ddb215 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -2110,7 +2110,7 @@ config CMD_DHCP
config CMD_DNS
bool "dns"
- select PROT_DNS_LWIP if NET_LWIP
+ select DNS
help
Lookup the IP of a hostname
diff --git a/cmd/lwip/dns.c b/cmd/lwip/dns.c
index b5fccc7433e..3eb698b3f82 100644
--- a/cmd/lwip/dns.c
+++ b/cmd/lwip/dns.c
@@ -2,115 +2,7 @@
/* Copyright (C) 2024 Linaro Ltd. */
#include <command.h>
-#include <console.h>
-#include <env.h>
-#include <lwip/dns.h>
-#include <lwip/timeouts.h>
#include <net.h>
-#include <time.h>
U_BOOT_CMD(dns, 3, 1, do_dns, "lookup the IP of a hostname",
"hostname [envvar]");
-
-#define DNS_RESEND_MS 1000
-#define DNS_TIMEOUT_MS 10000
-
-struct dns_cb_arg {
- ip_addr_t host_ipaddr;
- const char *var;
- bool done;
-};
-
-static void do_dns_tmr(void *arg)
-{
- dns_tmr();
-}
-
-static void dns_cb(const char *name, const ip_addr_t *ipaddr, void *arg)
-{
- struct dns_cb_arg *dns_cb_arg = arg;
- char *ipstr = ip4addr_ntoa(ipaddr);
-
- dns_cb_arg->done = true;
-
- if (!ipaddr) {
- printf("DNS: host not found\n");
- dns_cb_arg->host_ipaddr.addr = 0;
- return;
- }
-
- dns_cb_arg->host_ipaddr.addr = ipaddr->addr;
-
- if (dns_cb_arg->var)
- env_set(dns_cb_arg->var, ipstr);
-}
-
-static int dns_loop(struct udevice *udev, const char *name, const char *var)
-{
- struct dns_cb_arg dns_cb_arg = { };
- struct netif *netif;
- ip_addr_t ipaddr;
- ulong start;
- int ret;
-
- dns_cb_arg.var = var;
-
- netif = net_lwip_new_netif(udev);
- if (!netif)
- return CMD_RET_FAILURE;
-
- if (net_lwip_dns_init()) {
- net_lwip_remove_netif(netif);
- return CMD_RET_FAILURE;
- }
-
- dns_cb_arg.done = false;
-
- ret = dns_gethostbyname(name, &ipaddr, dns_cb, &dns_cb_arg);
-
- if (ret == ERR_OK) {
- dns_cb(name, &ipaddr, &dns_cb_arg);
- } else if (ret == ERR_INPROGRESS) {
- start = get_timer(0);
- sys_timeout(DNS_RESEND_MS, do_dns_tmr, NULL);
- do {
- net_lwip_rx(udev, netif);
- if (dns_cb_arg.done)
- break;
- if (ctrlc()) {
- printf("\nAbort\n");
- break;
- }
- } while (get_timer(start) < DNS_TIMEOUT_MS);
- sys_untimeout(do_dns_tmr, NULL);
- }
-
- net_lwip_remove_netif(netif);
-
- if (dns_cb_arg.done && dns_cb_arg.host_ipaddr.addr != 0) {
- if (!var)
- printf("%s\n", ipaddr_ntoa(&ipaddr));
- return CMD_RET_SUCCESS;
- }
-
- return CMD_RET_FAILURE;
-}
-
-int do_dns(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
-{
- char *name;
- char *var = NULL;
-
- if (argc == 1 || argc > 3)
- return CMD_RET_USAGE;
-
- name = argv[1];
-
- if (argc == 3)
- var = argv[2];
-
- if (net_lwip_eth_start() < 0)
- return CMD_RET_FAILURE;
-
- return dns_loop(eth_get_dev(), name, var);
-}
diff --git a/doc/usage/cmd/sntp.rst b/doc/usage/cmd/sntp.rst
index d97f83053f7..2046828130d 100644
--- a/doc/usage/cmd/sntp.rst
+++ b/doc/usage/cmd/sntp.rst
@@ -12,7 +12,7 @@ Synopsis
::
sntp [serverip]
- sntp [servername] # NET_LWIP=y && CMD_DNS=y only
+ sntp [servername] # NET_LWIP=y && DNS=y only
Description
@@ -27,8 +27,8 @@ The address of the NTP server does not need to be given if the DHCP server
provides one. The legacy network stack (`CONFIG_NET=y`) can only use the
first NTP server provided in the `ntp-servers` DHCP option.
-When the network stack is lwIP (`CONFIG_NET_LWIP=y`) and the dns command
-is enabled (`CONFIG_CMD_DNS=y`), then the sntp command accepts a server
+When the network stack is lwIP (`CONFIG_NET_LWIP=y`) and DNS resolution
+is enabled (`CONFIG_DNS=y`), then the sntp command accepts a server
name as an argument.
The network time is sent as UTC. So, if you want to set the RTC to any local
@@ -61,7 +61,7 @@ Examples
=> date
Date: 2025-06-16 (Monday) Time: 17:19:57
-With `CONFIG_NET_LWIP=y` and `CONFIG_CMD_DNS=y`:
+With `CONFIG_NET_LWIP=y` and `CONFIG_DNS=y`:
::
diff --git a/doc/usage/cmd/wget.rst b/doc/usage/cmd/wget.rst
index 06df2842549..8feda0248b2 100644
--- a/doc/usage/cmd/wget.rst
+++ b/doc/usage/cmd/wget.rst
@@ -38,7 +38,7 @@ address
memory address for the data downloaded
host
- IP address (or host name if `CONFIG_CMD_DNS` is enabled) of the HTTP
+ IP address (or host name if `CONFIG_DNS` is enabled) of the HTTP
server, defaults to the value of environment variable *serverip*.
path
diff --git a/include/net-legacy.h b/include/net-legacy.h
index a7dbcec1506..7ba5148a75a 100644
--- a/include/net-legacy.h
+++ b/include/net-legacy.h
@@ -316,7 +316,7 @@ extern u32 net_boot_file_size;
/* Boot file size in blocks as reported by the DHCP server */
extern u32 net_boot_file_expected_size_in_blocks;
-#if defined(CONFIG_CMD_DNS)
+#if defined(CONFIG_DNS)
extern char *net_dns_resolve; /* The host to resolve */
extern char *net_dns_env_var; /* the env var to put the ip into */
#endif
diff --git a/net/Kconfig b/net/Kconfig
index 24508026200..40ec6bbce76 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -244,11 +244,17 @@ config NET_RANDOM_ETHADDR
generated. It will be saved to the appropriate environment variable,
too.
+config DNS
+ bool "Enable DNS resolutions"
+ select PROT_DNS_LWIP if NET_LWIP
+ help
+ Selecting this will allow the network stack to use server names
+ in addition to IP addresses.
+
config WGET
bool "Enable wget"
select PROT_TCP if NET
select PROT_TCP_LWIP if NET_LWIP
- select PROT_DNS_LWIP if NET_LWIP
help
Selecting this will enable wget, an interface to send HTTP requests
via the network stack.
diff --git a/net/Makefile b/net/Makefile
index d63f62b7c8a..468820186cf 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -10,7 +10,7 @@ ifeq ($(CONFIG_NET),y)
obj-$(CONFIG_NET) += arp.o
obj-$(CONFIG_CMD_BOOTP) += bootp.o
obj-$(CONFIG_CMD_CDP) += cdp.o
-obj-$(CONFIG_CMD_DNS) += dns.o
+obj-$(CONFIG_DNS) += dns.o
obj-$(CONFIG_CMD_LINK_LOCAL) += link_local.o
obj-$(CONFIG_IPV6) += ndisc.o
obj-$(CONFIG_$(PHASE_)DM_ETH) += net.o
diff --git a/net/lwip/Makefile b/net/lwip/Makefile
index 97299d9b542..90d3300bd12 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_DNS) += dns.o
obj-$(CONFIG_CMD_TFTPBOOT) += tftp.o
obj-$(CONFIG_WGET) += wget.o
diff --git a/net/lwip/dns.c b/net/lwip/dns.c
new file mode 100644
index 00000000000..9964003195f
--- /dev/null
+++ b/net/lwip/dns.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0+
+/* Copyright (C) 2024 Linaro Ltd. */
+
+#include <command.h>
+#include <console.h>
+#include <env.h>
+#include <lwip/dns.h>
+#include <lwip/timeouts.h>
+#include <net.h>
+#include <time.h>
+
+#define DNS_RESEND_MS 1000
+#define DNS_TIMEOUT_MS 10000
+
+struct dns_cb_arg {
+ ip_addr_t host_ipaddr;
+ const char *var;
+ bool done;
+};
+
+static void do_dns_tmr(void *arg)
+{
+ dns_tmr();
+}
+
+static void dns_cb(const char *name, const ip_addr_t *ipaddr, void *arg)
+{
+ struct dns_cb_arg *dns_cb_arg = arg;
+ char *ipstr = ip4addr_ntoa(ipaddr);
+
+ dns_cb_arg->done = true;
+
+ if (!ipaddr) {
+ printf("DNS: host not found\n");
+ dns_cb_arg->host_ipaddr.addr = 0;
+ return;
+ }
+
+ dns_cb_arg->host_ipaddr.addr = ipaddr->addr;
+
+ if (dns_cb_arg->var)
+ env_set(dns_cb_arg->var, ipstr);
+}
+
+static int dns_loop(struct udevice *udev, const char *name, const char *var)
+{
+ struct dns_cb_arg dns_cb_arg = { };
+ struct netif *netif;
+ ip_addr_t ipaddr;
+ ulong start;
+ int ret;
+
+ dns_cb_arg.var = var;
+
+ netif = net_lwip_new_netif(udev);
+ if (!netif)
+ return CMD_RET_FAILURE;
+
+ if (net_lwip_dns_init()) {
+ net_lwip_remove_netif(netif);
+ return CMD_RET_FAILURE;
+ }
+
+ dns_cb_arg.done = false;
+
+ ret = dns_gethostbyname(name, &ipaddr, dns_cb, &dns_cb_arg);
+
+ if (ret == ERR_OK) {
+ dns_cb(name, &ipaddr, &dns_cb_arg);
+ } else if (ret == ERR_INPROGRESS) {
+ start = get_timer(0);
+ sys_timeout(DNS_RESEND_MS, do_dns_tmr, NULL);
+ do {
+ net_lwip_rx(udev, netif);
+ if (dns_cb_arg.done)
+ break;
+ if (ctrlc()) {
+ printf("\nAbort\n");
+ break;
+ }
+ } while (get_timer(start) < DNS_TIMEOUT_MS);
+ sys_untimeout(do_dns_tmr, NULL);
+ }
+
+ net_lwip_remove_netif(netif);
+
+ if (dns_cb_arg.done && dns_cb_arg.host_ipaddr.addr != 0) {
+ if (!var)
+ printf("%s\n", ipaddr_ntoa(&ipaddr));
+ return CMD_RET_SUCCESS;
+ }
+
+ return CMD_RET_FAILURE;
+}
+
+int do_dns(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+{
+ char *name;
+ char *var = NULL;
+
+ if (argc == 1 || argc > 3)
+ return CMD_RET_USAGE;
+
+ name = argv[1];
+
+ if (argc == 3)
+ var = argv[2];
+
+ if (net_lwip_eth_start() < 0)
+ return CMD_RET_FAILURE;
+
+ return dns_loop(eth_get_dev(), name, var);
+}
diff --git a/net/lwip/net-lwip.c b/net/lwip/net-lwip.c
index 3918d57d7e5..7069e56065f 100644
--- a/net/lwip/net-lwip.c
+++ b/net/lwip/net-lwip.c
@@ -147,7 +147,7 @@ static int get_udev_ipv4_info(struct udevice *dev, ip4_addr_t *ip,
*/
int net_lwip_dns_init(void)
{
-#if CONFIG_IS_ENABLED(CMD_DNS)
+#if CONFIG_IS_ENABLED(DNS)
bool has_server = false;
ip_addr_t ns;
char *nsenv;
@@ -369,7 +369,7 @@ int net_lwip_rx(struct udevice *udev, struct netif *netif)
*/
int net_lwip_dns_resolve(char *name_or_ip, ip_addr_t *ip)
{
-#if defined(CONFIG_CMD_DNS)
+#if defined(CONFIG_DNS)
char *var = "_dnsres";
char *argv[] = { "dns", name_or_ip, var, NULL };
int argc = ARRAY_SIZE(argv) - 1;
@@ -378,7 +378,7 @@ int net_lwip_dns_resolve(char *name_or_ip, ip_addr_t *ip)
if (ipaddr_aton(name_or_ip, ip))
return 0;
-#if defined(CONFIG_CMD_DNS)
+#if defined(CONFIG_DNS)
if (do_dns(NULL, 0, argc, argv) != CMD_RET_SUCCESS)
return -1;
diff --git a/net/net.c b/net/net.c
index 5219367e391..382a27e0a77 100644
--- a/net/net.c
+++ b/net/net.c
@@ -115,7 +115,7 @@
#include "bootp.h"
#include "cdp.h"
#include "dhcpv6.h"
-#if defined(CONFIG_CMD_DNS)
+#if defined(CONFIG_DNS)
#include "dns.h"
#endif
#include "link_local.h"
@@ -288,7 +288,7 @@ static int on_vlan(const char *name, const char *value, enum env_op op,
}
U_BOOT_ENV_CALLBACK(vlan, on_vlan);
-#if defined(CONFIG_CMD_DNS)
+#if defined(CONFIG_DNS)
static int on_dnsip(const char *name, const char *value, enum env_op op,
int flags)
{
@@ -582,7 +582,7 @@ restart:
nc_start();
break;
#endif
-#if defined(CONFIG_CMD_DNS)
+#if defined(CONFIG_DNS)
case DNS:
dns_start();
break;
@@ -1507,7 +1507,7 @@ static int net_check_prereq(enum proto_t protocol)
}
goto common;
#endif
-#if defined(CONFIG_CMD_DNS)
+#if defined(CONFIG_DNS)
case DNS:
if (net_dns_server.s_addr == 0) {
puts("*** ERROR: DNS server address not given\n");
@@ -1540,7 +1540,7 @@ static int net_check_prereq(enum proto_t protocol)
return 1;
}
#if defined(CONFIG_CMD_PING) || \
- defined(CONFIG_CMD_DNS) || defined(CONFIG_PROT_UDP)
+ defined(CONFIG_DNS) || defined(CONFIG_PROT_UDP)
common:
#endif
/* Fall through */
diff --git a/net/wget.c b/net/wget.c
index 3c0fff488eb..e65ce15ccb3 100644
--- a/net/wget.c
+++ b/net/wget.c
@@ -393,7 +393,7 @@ int wget_do_request(ulong dst_addr, char *uri)
if (string_to_ip(host_name).s_addr) {
s = host_name;
} else {
-#if IS_ENABLED(CONFIG_CMD_DNS)
+#if IS_ENABLED(CONFIG_DNS)
net_dns_resolve = host_name;
net_dns_env_var = "httpserverip";
if (net_loop(DNS) < 0) {
--
2.43.0
base-commit: 0f83825802d8938fb584c12f115bde900efe71c1
branch: introduce-dns-kconfig
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