opt.h, netif.h, dhcp.h, dhcp.c: New configuration option LWIP_NETIF_HOSTNAME allow to define a hostname in netif struct (this is just a pointer, so, you can use a hardcoded string, point on one of your's ethernetif field, or alloc a string you will free yourself). It will be used by DHCP to register a client hostname, but can also be use when you call snmp_set_sysname.

src/include/lwip/dhcp.h

@@ -210,6 +210,7 @@ void dhcp_fine_tmr(void);
 
 #define DHCP_OPTION_T1 58 /* T1 renewal time */
 #define DHCP_OPTION_T2 59 /* T2 rebinding time */
+#define DHCP_OPTION_US 60
 #define DHCP_OPTION_CLIENT_ID 61
 #define DHCP_OPTION_TFTP_SERVERNAME 66
 #define DHCP_OPTION_BOOTFILE 67

src/include/lwip/netif.h

@@ -104,6 +104,10 @@ struct netif {
   /** the DHCP client state information for this netif */
   struct dhcp *dhcp;
 #endif /* LWIP_DHCP */
+#if LWIP_NETIF_HOSTNAME
+  /* the hostname for this netif, NULL is a valid value */
+  char*  hostname;
+#endif /* LWIP_NETIF_HOSTNAME */
   /** number of bytes used in hwaddr */
   u8_t hwaddr_len;
   /** link level hardware address of this interface */

src/include/lwip/opt.h

@@ -383,6 +383,13 @@ a lot of data that needs to be copied, this should be set high. */
 #define TCP_SNDLOWAT                    TCP_SND_BUF/2
 #endif
 
+
+/* ---- Network Interfaces options ---- */
+/* 1 if you want to use DHCP_OPTION_HOSTNAME with netif's hostname field */
+#ifndef LWIP_NETIF_HOSTNAME
+#define LWIP_NETIF_HOSTNAME             0
+#endif
+
 /* Support network interface callbacks */
 #ifndef LWIP_NETIF_CALLBACK
 #define LWIP_NETIF_CALLBACK             0
@@ -401,6 +408,8 @@ a lot of data that needs to be copied, this should be set high. */
 #define LWIP_CALLBACK_API               0
 #endif 
 
+
+/* ---------- Thread options ---------- */
 #ifndef TCPIP_THREAD_PRIO
 #define TCPIP_THREAD_PRIO               1
 #endif
@@ -418,7 +427,7 @@ a lot of data that needs to be copied, this should be set high. */
 #endif
 
 
-/* ---------- Socket Options ---------- */
+/* ---------- Socket options ---------- */
 /* Enable BSD-style sockets functions names */
 #ifndef LWIP_COMPAT_SOCKETS
 #define LWIP_COMPAT_SOCKETS             1