From 3081eeb556bd35abf2cf46f27d6252bb12dbca8e Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Sat, 10 Jul 2021 15:05:03 +0200
Subject: [PATCH] netutils: add netutils_get_ipv6()

---
 sys/Makefile              |  3 ++
 sys/Makefile.dep          |  4 ++
 sys/include/net/utils.h   | 52 ++++++++++++++++++++++++++
 sys/net/netutils/Makefile |  3 ++
 sys/net/netutils/util.c   | 78 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 140 insertions(+)
 create mode 100644 sys/include/net/utils.h
 create mode 100644 sys/net/netutils/Makefile
 create mode 100644 sys/net/netutils/util.c

diff --git a/sys/Makefile b/sys/Makefile
index eade1daea3..50a11546f5 100644
--- a/sys/Makefile
+++ b/sys/Makefile
@@ -113,6 +113,9 @@ endif
 ifneq (,$(filter netstats_neighbor,$(USEMODULE)))
   DIRS += net/netstats
 endif
+ifneq (,$(filter netutils,$(USEMODULE)))
+  DIRS += net/netutils
+endif
 ifneq (,$(filter sema,$(USEMODULE)))
   DIRS += sema
 endif
diff --git a/sys/Makefile.dep b/sys/Makefile.dep
index 9e1bd58772..04598a119b 100644
--- a/sys/Makefile.dep
+++ b/sys/Makefile.dep
@@ -185,6 +185,10 @@ ifneq (,$(filter od_string,$(USEMODULE)))
   USEMODULE += od
 endif
 
+ifneq (,$(filter netutils,$(USEMODULE)))
+  USEMODULE += ipv6_addr
+endif
+
 ifneq (,$(filter newlib_gnu_source,$(USEMODULE)))
   FEATURES_REQUIRED += newlib
 endif
diff --git a/sys/include/net/utils.h b/sys/include/net/utils.h
new file mode 100644
index 0000000000..662c3704b0
--- /dev/null
+++ b/sys/include/net/utils.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup    net_utils   Network helper functions
+ * @ingroup     net
+ * @brief       Common network helper functions
+ * @{
+ *
+ * @file
+ * @brief       Common network interface API definitions
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+
+#ifndef NET_UTILS_H
+#define NET_UTILS_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+#include "net/ipv6/addr.h"
+#include "net/netif.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Parse an IPv6 address / hostname string.
+ *          If the @ref net_sock_dns module is used, this will
+ *          attempt to resolve hostnames via DNS to IPv6 addresses.
+ *
+ * @param[out]  addr        IPv6 address of the host
+ * @param[out]  netif       Interface if address is link-local
+ * @param[in]   hostname    IPv6 address string or hostname
+ *
+ * @return  0 on success, error otherwise
+ */
+int netutils_get_ipv6(ipv6_addr_t *addr, netif_t **netif, const char *hostname);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NET_UTILS_H */
+/** @} */
diff --git a/sys/net/netutils/Makefile b/sys/net/netutils/Makefile
new file mode 100644
index 0000000000..dc07bd13e5
--- /dev/null
+++ b/sys/net/netutils/Makefile
@@ -0,0 +1,3 @@
+MODULE = netutils
+
+include $(RIOTBASE)/Makefile.base
diff --git a/sys/net/netutils/util.c b/sys/net/netutils/util.c
new file mode 100644
index 0000000000..5fbaaabd1c
--- /dev/null
+++ b/sys/net/netutils/util.c
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2021 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @{
+ *
+ * @file
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "net/utils.h"
+#ifdef MODULE_SOCK_DNS
+#include "net/af.h"
+#include "net/sock/dns.h"
+#endif
+
+/* get the next netif, returns true if there are more */
+static bool _netif_get(netif_t **current_netif)
+{
+    netif_t *netif = *current_netif;
+    netif = netif_iter(netif);
+
+    *current_netif = netif;
+    return netif_iter(netif);
+}
+
+int netutils_get_ipv6(ipv6_addr_t *addr, netif_t **netif, const char *hostname)
+{
+    *netif = NULL;
+
+    if (hostname == NULL) {
+        return -EINVAL;
+    }
+
+#ifdef MODULE_SOCK_DNS
+    /* hostname is not an IPv6 address */
+    if (strchr(hostname, ':') == NULL) {
+        int res = sock_dns_query(hostname, addr, AF_INET6);
+        if (res < 0) {
+            return res;
+        }
+        return 0;
+    }
+#endif
+
+    /* search for interface ID */
+    size_t len = strlen(hostname);
+    char *iface = strchr(hostname, '%');
+    if (iface) {
+        *netif = netif_get_by_id(atoi(iface + 1));
+        len -= strlen(iface);
+
+        if (*netif == NULL) {
+            return -EINVAL;
+        }
+    }
+    /* preliminary select the first interface */
+    else if (_netif_get(netif)) {
+        /* don't take it if there is more than one interface */
+        *netif = NULL;
+    }
+
+    if (ipv6_addr_from_buf(addr, hostname, len) == NULL) {
+         return -EINVAL;
+    }
+
+    return 0;
+}
+/** @} */