net: Add hostname setting to Kconfig

User can configure hostname of the device in Kconfig. This can
be used by mDNS responder to answer <hostname>.local queries.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

include/net/hostname.h

@@ -0,0 +1,82 @@
+/** @file
+ * @brief Hostname configuration definitions
+ */
+
+/*
+ * Copyright (c) 2017 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef __NET_HOSTNAME_H
+#define __NET_HOSTNAME_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Network hostname configuration library
+ * @defgroup net_hostname Network Hostname Library
+ * @{
+ */
+
+#if defined(CONFIG_NET_HOSTNAME_ENABLE)
+/**
+ * @brief Get the device hostname
+ *
+ * @details Return pointer to device hostname.
+ *
+ * @return Pointer to hostname or NULL if not set.
+ */
+const char *net_hostname_get(void);
+
+/**
+ * @brief Initialize and set the device hostname.
+ *
+ */
+void net_hostname_init(void);
+
+#else
+static inline const char *net_hostname_get(void)
+{
+	return NULL;
+}
+
+static inline void net_hostname_init(void)
+{
+}
+#endif /* CONFIG_NET_HOSTNAME_ENABLE */
+
+#if defined(CONFIG_NET_HOSTNAME_UNIQUE)
+/**
+ * @brief Set the device hostname postfix
+ *
+ * @details Set the device hostname to some value. This is only used if
+ * CONFIG_NET_HOSTNAME_UNIQUE is set.
+ *
+ * @param hostname_postfix Usually link address. The function will convert this
+ * to a string.
+ * @param postfix_len Length of the hostname_postfix array.
+ *
+ * @return 0 if ok, <0 if error
+ */
+int net_hostname_set_postfix(const u8_t *hostname_postfix,
+			      int postfix_len);
+#else
+static inline int net_hostname_set_postfix(const u8_t *hostname_postfix,
+					   int postfix_len)
+{
+	return -EMSGSIZE;
+}
+#endif /* CONFIG_NET_HOSTNAME_UNIQUE */
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __NET_HOSTNAME_H */

include/net/net_if.h

@@ -22,6 +22,7 @@
 #include <misc/slist.h>
 
 #include <net/net_core.h>
+#include <net/hostname.h>
 #include <net/net_linkaddr.h>
 #include <net/net_ip.h>
 #include <net/net_l2.h>
@@ -453,6 +454,8 @@ static inline int net_if_set_link_addr(struct net_if *iface,
 	iface->link_addr.len = len;
 	iface->link_addr.type = type;
 
+	net_hostname_set_postfix(addr, len);
+
 	return 0;
 }
 

subsys/net/Kconfig

@@ -81,6 +81,8 @@ config  NETWORKING
 
 if NETWORKING
 
+source "subsys/net/Kconfig.hostname"
+
 source "subsys/net/ip/Kconfig"
 
 source "subsys/net/lib/Kconfig"

subsys/net/Kconfig.hostname

@@ -0,0 +1,39 @@
+# Kconfig - Hostname config
+
+#
+# Copyright (c) 2017 Intel Corporation.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+config NET_HOSTNAME_ENABLE
+	bool "Add hostname to the device"
+	default n
+	help
+	This is used for example in mDNS to respond to <hostname>.local
+	mDNS queries.
+
+if NET_HOSTNAME_ENABLE
+
+config NET_HOSTNAME
+	string "The hostname of this device"
+	default "zephyr"
+	help
+	The string should be a valid hostname.
+
+config NET_HOSTNAME_UNIQUE
+	bool "Make hostname unique"
+	default n
+	help
+	This will append link address to hostname to create a unique
+	hostname. For example, zephyr00005e005357 could be the hostname
+	if this	setting is enabled.
+
+config  NET_DEBUG_HOSTNAME
+	bool "Debug hostname configuration"
+	default n
+	depends on NET_LOG
+	help
+	Enables hostname configuration functions to output debug messages
+
+endif

subsys/net/Makefile

@@ -1,4 +1,5 @@
 obj-$(CONFIG_NET_BUF) += buf.o
+obj-$(CONFIG_NET_HOSTNAME_ENABLE) += hostname.o
 
 ifeq ($(CONFIG_NETWORKING),y)
 ifeq ($(CONFIG_NET_L2_RAW_CHANNEL),y)

subsys/net/hostname.c

@@ -0,0 +1,72 @@
+/** @file
+ * @brief Hostname configuration
+ */
+
+/*
+ * Copyright (c) 2017 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#if defined(CONFIG_NET_DEBUG_HOSTNAME)
+#define SYS_LOG_DOMAIN "net/hostname"
+#define NET_LOG_ENABLED 1
+#endif
+
+#include <zephyr.h>
+
+#include <net/net_core.h>
+
+#if defined(CONFIG_NET_HOSTNAME_UNIQUE)
+/* Allocate extra space to append MAC address to hostname */
+#define EXTRA_SPACE (8 * 2)
+#else
+#define EXTRA_SPACE 0
+#endif /* CONFIG_NET_HOSTNAME_UNIQUE */
+
+static char hostname[sizeof(CONFIG_NET_HOSTNAME) - 1 + EXTRA_SPACE];
+
+const char *net_hostname_get(void)
+{
+	return hostname;
+}
+
+#if defined(CONFIG_NET_HOSTNAME_UNIQUE)
+int net_hostname_set_postfix(const u8_t *hostname_postfix,
+			     int postfix_len)
+{
+	static bool postfix_set;
+	int pos = 0;
+	int i;
+
+	if (postfix_set) {
+		return -EALREADY;
+	}
+
+	NET_ASSERT(postfix_len > 0);
+
+	/* Note that we convert the postfix to hex (2 chars / byte) */
+	if ((postfix_len * 2) >
+	    ((sizeof(hostname) - 1) - (sizeof(CONFIG_NET_HOSTNAME) - 1))) {
+		return -EMSGSIZE;
+	}
+
+	for (i = 0; i < postfix_len; i++, pos += 2) {
+		snprintk(&hostname[sizeof(CONFIG_NET_HOSTNAME) - 1 + pos],
+			 2 + 1, "%02x", hostname_postfix[i]);
+	}
+
+	NET_DBG("New hostname %s", hostname);
+
+	postfix_set = true;
+
+	return 0;
+}
+#endif /* CONFIG_NET_HOSTNAME_UNIQUE */
+
+void net_hostname_init(void)
+{
+	memcpy(hostname, CONFIG_NET_HOSTNAME, sizeof(CONFIG_NET_HOSTNAME) - 1);
+
+	NET_DBG("Hostname set to %s", hostname);
+}

subsys/net/ip/net_core.c

@@ -381,6 +381,8 @@ static int net_init(struct device *unused)
 {
 	int status = 0;
 
+	net_hostname_init();
+
 	NET_DBG("Priority %d", CONFIG_NET_INIT_PRIO);
 
 	net_pkt_init();