From 9587a271f602a0c15c3b858c27f23a4800935bf9 Mon Sep 17 00:00:00 2001
From: Luuk Bosma <l.bosma@interay.com>
Date: Fri, 21 Feb 2020 12:24:22 +0100
Subject: [PATCH] net/ip/dhcpv4: Set Host Name in DHCP Request

This option specifies the name of the client.
See https://tools.ietf.org/html/rfc2132#section-3.14

This is useful for identification when looking in DHCP lease table.

Signed-off-by: Luuk Bosma <l.bosma@interay.com>
---
 subsys/net/ip/dhcpv4.c | 26 ++++++++++++++++++++++++++
 subsys/net/ip/dhcpv4.h |  2 ++
 2 files changed, 28 insertions(+)

diff --git a/subsys/net/ip/dhcpv4.c b/subsys/net/ip/dhcpv4.c
index f0a8b0add52..c028bb4de1c 100644
--- a/subsys/net/ip/dhcpv4.c
+++ b/subsys/net/ip/dhcpv4.c
@@ -117,6 +117,15 @@ static bool dhcpv4_add_req_ipaddr(struct net_pkt *pkt,
 					      4, addr->s4_addr);
 }
 
+#if defined(CONFIG_NET_HOSTNAME_ENABLE)
+static bool dhcpv4_add_hostname(struct net_pkt *pkt,
+				 const char *hostname, const size_t size)
+{
+	return dhcpv4_add_option_length_value(pkt, DHCPV4_OPTIONS_HOST_NAME,
+					      size, hostname);
+}
+#endif
+
 /* Add DHCPv4 Options end, rest of the message can be padded wit zeros */
 static inline bool dhcpv4_add_end(struct net_pkt *pkt)
 {
@@ -159,6 +168,10 @@ static struct net_pkt *dhcpv4_create_message(struct net_if *iface, u8_t type,
 	size_t size = DHCPV4_MESSAGE_SIZE;
 	struct net_pkt *pkt;
 	struct dhcp_msg *msg;
+#if defined(CONFIG_NET_HOSTNAME_ENABLE)
+	const char *hostname = net_hostname_get();
+	const size_t hostname_size = strlen(hostname);
+#endif
 
 	if (src_addr == NULL) {
 		addr = net_ipv4_unspecified_address();
@@ -178,6 +191,12 @@ static struct net_pkt *dhcpv4_create_message(struct net_if *iface, u8_t type,
 		size +=  DHCPV4_OLV_MSG_REQ_LIST;
 	}
 
+#if defined(CONFIG_NET_HOSTNAME_ENABLE)
+	if (hostname_size > 0) {
+		size += DHCPV4_OLV_MSG_HOST_NAME + hostname_size;
+	}
+#endif
+
 	pkt = net_pkt_alloc_with_buffer(iface, size, AF_INET,
 					IPPROTO_UDP, K_FOREVER);
 
@@ -232,6 +251,13 @@ static struct net_pkt *dhcpv4_create_message(struct net_if *iface, u8_t type,
 		goto fail;
 	}
 
+#if defined(CONFIG_NET_HOSTNAME_ENABLE)
+	if (hostname_size > 0 &&
+	     !dhcpv4_add_hostname(pkt, hostname, hostname_size)) {
+		goto fail;
+	}
+#endif
+
 	if (!dhcpv4_add_end(pkt)) {
 		goto fail;
 	}
diff --git a/subsys/net/ip/dhcpv4.h b/subsys/net/ip/dhcpv4.h
index 6e1ab31f57e..1828b142973 100644
--- a/subsys/net/ip/dhcpv4.h
+++ b/subsys/net/ip/dhcpv4.h
@@ -69,6 +69,7 @@ enum dhcpv4_msg_type {
 #define DHCPV4_OPTIONS_SUBNET_MASK	1
 #define DHCPV4_OPTIONS_ROUTER		3
 #define DHCPV4_OPTIONS_DNS_SERVER	6
+#define DHCPV4_OPTIONS_HOST_NAME	12
 #define DHCPV4_OPTIONS_REQ_IPADDR	50
 #define DHCPV4_OPTIONS_LEASE_TIME	51
 #define DHCPV4_OPTIONS_MSG_TYPE		53
@@ -79,6 +80,7 @@ enum dhcpv4_msg_type {
 #define DHCPV4_OPTIONS_END		255
 
 /* Useful size macros */
+#define DHCPV4_OLV_MSG_HOST_NAME	2
 #define DHCPV4_OLV_MSG_REQ_IPADDR	6
 #define DHCPV4_OLV_MSG_TYPE_SIZE	3
 #define DHCPV4_OLV_MSG_SERVER_ID	6