[PATCHv8 03/15] net/lwip: implement dns cmd

[Maxim Uvarov]

U-Boot recently got support for an alternative network stack using LWIP.
Replace dns command with the LWIP variant while keeping the output and
error messages identical.

Signed-off-by: Maxim Uvarov <maxim.uvarov at linaro.org>
---
 include/net/lwip.h           | 19 +++++++++++
 net/lwip/Makefile            |  2 ++
 net/lwip/apps/dns/lwip-dns.c | 63 ++++++++++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+)
 create mode 100644 include/net/lwip.h
 create mode 100644 net/lwip/apps/dns/lwip-dns.c

diff --git a/include/net/lwip.h b/include/net/lwip.h
new file mode 100644
index 0000000000..ab3db1a214
--- /dev/null
+++ b/include/net/lwip.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+int do_lwip_dns(struct cmd_tbl *cmdtp, int flag, int argc,
+		char *const argv[]);
+
+/**
+ * ulwip_dns() - creates the DNS request to resolve a domain host name
+ *
+ * This function creates the DNS request to resolve a domain host name. Function
+ * can return immediately if previous request was cached or it might require
+ * entering the polling loop for a request to a remote server.
+ *
+ * @name:    dns name to resolve
+ * @varname: (optional) U-Boot variable name to store the result
+ * Returns: ERR_OK(0) for fetching entry from the cache
+ *          -EINPROGRESS success, can go to the polling loop
+ *          Other value < 0, if error
+ */
+int ulwip_dns(char *name, char *varname);
diff --git a/net/lwip/Makefile b/net/lwip/Makefile
index 3fd5d34564..5d8d5527c6 100644
--- a/net/lwip/Makefile
+++ b/net/lwip/Makefile
@@ -62,3 +62,5 @@ obj-$(CONFIG_NET) += lwip-external/src/netif/ethernet.o
 
 obj-$(CONFIG_NET) += port/if.o
 obj-$(CONFIG_NET) += port/sys-arch.o
+
+obj-y += apps/dns/lwip-dns.o
diff --git a/net/lwip/apps/dns/lwip-dns.c b/net/lwip/apps/dns/lwip-dns.c
new file mode 100644
index 0000000000..b340302f2c
--- /dev/null
+++ b/net/lwip/apps/dns/lwip-dns.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * (C) Copyright 2023 Linaro Ltd. <maxim.uvarov at linaro.org>
+ */
+
+#include <common.h>
+#include <command.h>
+#include <console.h>
+
+#include <lwip/dns.h>
+#include <lwip/ip_addr.h>
+
+#include <net/ulwip.h>
+
+static void dns_found_cb(const char *name, const ip_addr_t *ipaddr, void *callback_arg)
+{
+	char *varname = (char *)callback_arg;
+	char *ipstr = ip4addr_ntoa(ipaddr);
+
+	if (varname)
+		env_set(varname, ipstr);
+	log_info("resolved %s to %s\n",  name, ipstr);
+	ulwip_exit(0);
+}
+
+int ulwip_dns(char *name, char *varname)
+{
+	int err;
+	ip_addr_t ipaddr; /* not used */
+	ip_addr_t dns1;
+	ip_addr_t dns2;
+	char *dnsenv = env_get("dnsip");
+	char *dns2env = env_get("dnsip2");
+
+	if (!dnsenv && !dns2env) {
+		log_err("nameserver is not set with dnsip and dnsip2 vars\n");
+		return -ENOENT;
+	}
+
+	if (!dnsenv)
+		log_warning("dnsip var is not set\n");
+	if (!dns2env)
+		log_warning("dnsip2 var is not set\n");
+
+	dns_init();
+
+	if (ipaddr_aton(dnsenv, &dns1))
+		dns_setserver(0, &dns1);
+
+	if (ipaddr_aton(dns2env, &dns2))
+		dns_setserver(1, &dns2);
+
+	err = dns_gethostbyname(name, &ipaddr, dns_found_cb, varname);
+	if (err == ERR_OK)
+		dns_found_cb(name, &ipaddr, varname);
+
+	/* convert lwIP ERR_INPROGRESS to U-Boot -EINPROGRESS */
+	if (err == ERR_INPROGRESS)
+		err = -EINPROGRESS;
+
+	return err;
+}
-- 
2.30.2