From f9cb6ec2fa2895fb206befda0eb4506e85ef5537 Mon Sep 17 00:00:00 2001
From: Adam Dunkels <adam@thingsquare.com>
Date: Sat, 16 Nov 2013 14:42:57 +0100
Subject: [PATCH 1/2] Added the const keyword to IP address arguments that are
 not (and should not be) changed by the callee

---
 core/net/nbr-table.c             |  6 +++---
 core/net/nbr-table.h             |  2 +-
 core/net/rpl/rpl-dag.c           |  8 ++++----
 core/net/rpl/rpl.h               |  2 +-
 core/net/sicslowpan.c            |  2 +-
 core/net/tcpip.c                 |  6 +++---
 core/net/tcpip.h                 |  4 ++--
 core/net/uip-ds6-nbr.c           | 24 ++++++++++++------------
 core/net/uip-ds6-nbr.h           | 14 +++++++-------
 core/net/uip-ds6-route.c         |  4 ++--
 core/net/uip-nd6.c               |  4 ++--
 examples/ravenusbstick/fakeuip.c |  4 ++--
 12 files changed, 40 insertions(+), 40 deletions(-)

diff --git a/core/net/nbr-table.c b/core/net/nbr-table.c
index f5d53c333..d8eaaa385 100644
--- a/core/net/nbr-table.c
+++ b/core/net/nbr-table.c
@@ -86,7 +86,7 @@ index_from_key(nbr_table_key_t *key)
 /*---------------------------------------------------------------------------*/
 /* Get the neighbor index of an item */
 static int
-index_from_item(nbr_table_t *table, nbr_table_item_t *item)
+index_from_item(nbr_table_t *table, const nbr_table_item_t *item)
 {
   return table != NULL && item != NULL ? ((int)((char *)item - (char *)table->data)) / table->item_size : -1;
 }
@@ -100,7 +100,7 @@ item_from_key(nbr_table_t *table, nbr_table_key_t *key)
 /*---------------------------------------------------------------------------*/
 /* Get the key af an item */
 static nbr_table_key_t *
-key_from_item(nbr_table_t *table, nbr_table_item_t *item)
+key_from_item(nbr_table_t *table, const nbr_table_item_t *item)
 {
   return key_from_index(index_from_item(table, item));
 }
@@ -343,7 +343,7 @@ nbr_table_unlock(nbr_table_t *table, void *item)
 /*---------------------------------------------------------------------------*/
 /* Get link-layer address of an item */
 rimeaddr_t *
-nbr_table_get_lladdr(nbr_table_t *table, void *item)
+nbr_table_get_lladdr(nbr_table_t *table, const void *item)
 {
   nbr_table_key_t *key = key_from_item(table, item);
   return key != NULL ? &key->lladdr : NULL;
diff --git a/core/net/nbr-table.h b/core/net/nbr-table.h
index 113db94b6..763c0d2a5 100644
--- a/core/net/nbr-table.h
+++ b/core/net/nbr-table.h
@@ -97,7 +97,7 @@ int nbr_table_unlock(nbr_table_t *table, nbr_table_item_t *item);
 
 /** \name Neighbor tables: address manipulation */
 /** @{ */
-rimeaddr_t *nbr_table_get_lladdr(nbr_table_t *table, nbr_table_item_t *item);
+rimeaddr_t *nbr_table_get_lladdr(nbr_table_t *table, const nbr_table_item_t *item);
 /** @} */
 
 #endif /* _NBR_TABLE_H_ */
diff --git a/core/net/rpl/rpl-dag.c b/core/net/rpl/rpl-dag.c
index 9f396202f..f7d37a6e5 100644
--- a/core/net/rpl/rpl-dag.c
+++ b/core/net/rpl/rpl-dag.c
@@ -96,9 +96,9 @@ rpl_get_parent_rank(uip_lladdr_t *addr)
 }
 /*---------------------------------------------------------------------------*/
 uint16_t
-rpl_get_parent_link_metric(uip_lladdr_t *addr)
+rpl_get_parent_link_metric(const uip_lladdr_t *addr)
 {
-  rpl_parent_t *p = nbr_table_get_from_lladdr(rpl_parents, (rimeaddr_t *)addr);
+  rpl_parent_t *p = nbr_table_get_from_lladdr(rpl_parents, (const rimeaddr_t *)addr);
   if(p != NULL) {
     return p->link_metric;
   } else {
@@ -539,7 +539,7 @@ rpl_add_parent(rpl_dag_t *dag, rpl_dio_t *dio, uip_ipaddr_t *addr)
   rpl_parent_t *p = NULL;
   /* Is the parent known by ds6? Drop this request if not.
    * Typically, the parent is added upon receiving a DIO. */
-  uip_lladdr_t *lladdr = uip_ds6_nbr_lladdr_from_ipaddr(addr);
+  const uip_lladdr_t *lladdr = uip_ds6_nbr_lladdr_from_ipaddr(addr);
 
   PRINTF("RPL: rpl_add_parent lladdr %p\n", lladdr);
   if(lladdr != NULL) {
@@ -561,7 +561,7 @@ static rpl_parent_t *
 find_parent_any_dag_any_instance(uip_ipaddr_t *addr)
 {
   uip_ds6_nbr_t *ds6_nbr = uip_ds6_nbr_lookup(addr);
-  uip_lladdr_t *lladdr = uip_ds6_nbr_get_ll(ds6_nbr);
+  const uip_lladdr_t *lladdr = uip_ds6_nbr_get_ll(ds6_nbr);
   return nbr_table_get_from_lladdr(rpl_parents, (rimeaddr_t *)lladdr);
 }
 /*---------------------------------------------------------------------------*/
diff --git a/core/net/rpl/rpl.h b/core/net/rpl/rpl.h
index dd3ccd9eb..b83e140ed 100644
--- a/core/net/rpl/rpl.h
+++ b/core/net/rpl/rpl.h
@@ -245,7 +245,7 @@ void rpl_remove_header(void);
 uint8_t rpl_invert_header(void);
 uip_ipaddr_t *rpl_get_parent_ipaddr(rpl_parent_t *nbr);
 rpl_rank_t rpl_get_parent_rank(uip_lladdr_t *addr);
-uint16_t rpl_get_parent_link_metric(uip_lladdr_t *addr);
+uint16_t rpl_get_parent_link_metric(const uip_lladdr_t *addr);
 void rpl_dag_init(void);
 /*---------------------------------------------------------------------------*/
 #endif /* RPL_H */
diff --git a/core/net/sicslowpan.c b/core/net/sicslowpan.c
index cdbe33fc8..be6a2dc8d 100644
--- a/core/net/sicslowpan.c
+++ b/core/net/sicslowpan.c
@@ -1354,7 +1354,7 @@ send_packet(rimeaddr_t *dest)
  *  MAC.
  */
 static uint8_t
-output(uip_lladdr_t *localdest)
+output(const uip_lladdr_t *localdest)
 {
   int framer_hdrlen;
 
diff --git a/core/net/tcpip.c b/core/net/tcpip.c
index 1bd84f6e2..5d9d8858a 100644
--- a/core/net/tcpip.c
+++ b/core/net/tcpip.c
@@ -109,10 +109,10 @@ enum {
 /* Called on IP packet output. */
 #if UIP_CONF_IPV6
 
-static uint8_t (* outputfunc)(uip_lladdr_t *a);
+static uint8_t (* outputfunc)(const uip_lladdr_t *a);
 
 uint8_t
-tcpip_output(uip_lladdr_t *a)
+tcpip_output(const uip_lladdr_t *a)
 {
   int ret;
   if(outputfunc != NULL) {
@@ -124,7 +124,7 @@ tcpip_output(uip_lladdr_t *a)
 }
 
 void
-tcpip_set_outputfunc(uint8_t (*f)(uip_lladdr_t *))
+tcpip_set_outputfunc(uint8_t (*f)(const uip_lladdr_t *))
 {
   outputfunc = f;
 }
diff --git a/core/net/tcpip.h b/core/net/tcpip.h
index 705fe4554..bb4b412b5 100644
--- a/core/net/tcpip.h
+++ b/core/net/tcpip.h
@@ -340,8 +340,8 @@ CCIF void tcpip_input(void);
  * The eventual parameter is the MAC address of the destination.
  */
 #if UIP_CONF_IPV6
-uint8_t tcpip_output(uip_lladdr_t *);
-void tcpip_set_outputfunc(uint8_t (* f)(uip_lladdr_t *));
+uint8_t tcpip_output(const uip_lladdr_t *);
+void tcpip_set_outputfunc(uint8_t (* f)(const uip_lladdr_t *));
 #else
 uint8_t tcpip_output(void);
 void tcpip_set_outputfunc(uint8_t (* f)(void));
diff --git a/core/net/uip-ds6-nbr.c b/core/net/uip-ds6-nbr.c
index 924e9ba3d..2f07154dc 100644
--- a/core/net/uip-ds6-nbr.c
+++ b/core/net/uip-ds6-nbr.c
@@ -78,7 +78,7 @@ uip_ds6_neighbors_init(void)
 }
 /*---------------------------------------------------------------------------*/
 uip_ds6_nbr_t *
-uip_ds6_nbr_add(uip_ipaddr_t *ipaddr, uip_lladdr_t *lladdr,
+uip_ds6_nbr_add(const uip_ipaddr_t *ipaddr, const uip_lladdr_t *lladdr,
                 uint8_t isrouter, uint8_t state)
 {
   uip_ds6_nbr_t *nbr = nbr_table_add_lladdr(ds6_neighbors, (rimeaddr_t*)lladdr);
@@ -125,17 +125,17 @@ uip_ds6_nbr_rm(uip_ds6_nbr_t *nbr)
 }
 
 /*---------------------------------------------------------------------------*/
-uip_ipaddr_t *
-uip_ds6_nbr_get_ipaddr(uip_ds6_nbr_t *nbr)
+const uip_ipaddr_t *
+uip_ds6_nbr_get_ipaddr(const uip_ds6_nbr_t *nbr)
 {
   return (nbr != NULL) ? &nbr->ipaddr : NULL;
 }
 
 /*---------------------------------------------------------------------------*/
-uip_lladdr_t *
-uip_ds6_nbr_get_ll(uip_ds6_nbr_t *nbr)
+const uip_lladdr_t *
+uip_ds6_nbr_get_ll(const uip_ds6_nbr_t *nbr)
 {
-  return (uip_lladdr_t *)nbr_table_get_lladdr(ds6_neighbors, nbr);
+  return (const uip_lladdr_t *)nbr_table_get_lladdr(ds6_neighbors, nbr);
 }
 /*---------------------------------------------------------------------------*/
 int
@@ -154,7 +154,7 @@ uip_ds6_nbr_num(void)
 }
 /*---------------------------------------------------------------------------*/
 uip_ds6_nbr_t *
-uip_ds6_nbr_lookup(uip_ipaddr_t *ipaddr)
+uip_ds6_nbr_lookup(const uip_ipaddr_t *ipaddr)
 {
   uip_ds6_nbr_t *nbr = nbr_table_head(ds6_neighbors);
   if(ipaddr != NULL) {
@@ -169,22 +169,22 @@ uip_ds6_nbr_lookup(uip_ipaddr_t *ipaddr)
 }
 /*---------------------------------------------------------------------------*/
 uip_ds6_nbr_t *
-uip_ds6_nbr_ll_lookup(uip_lladdr_t *lladdr)
+uip_ds6_nbr_ll_lookup(const uip_lladdr_t *lladdr)
 {
   return nbr_table_get_from_lladdr(ds6_neighbors, (rimeaddr_t*)lladdr);
 }
 
 /*---------------------------------------------------------------------------*/
 uip_ipaddr_t *
-uip_ds6_nbr_ipaddr_from_lladdr(uip_lladdr_t *lladdr)
+uip_ds6_nbr_ipaddr_from_lladdr(const uip_lladdr_t *lladdr)
 {
   uip_ds6_nbr_t *nbr = uip_ds6_nbr_ll_lookup(lladdr);
   return nbr ? &nbr->ipaddr : NULL;
 }
 
 /*---------------------------------------------------------------------------*/
-uip_lladdr_t *
-uip_ds6_nbr_lladdr_from_ipaddr(uip_ipaddr_t *ipaddr)
+const uip_lladdr_t *
+uip_ds6_nbr_lladdr_from_ipaddr(const uip_ipaddr_t *ipaddr)
 {
   uip_ds6_nbr_t *nbr = uip_ds6_nbr_lookup(ipaddr);
   return nbr ? uip_ds6_nbr_get_ll(nbr) : NULL;
@@ -276,7 +276,6 @@ uip_ds6_neighbor_periodic(void)
     nbr = nbr_table_next(ds6_neighbors, nbr);
   }
 }
-
 /*---------------------------------------------------------------------------*/
 uip_ds6_nbr_t *
 uip_ds6_get_least_lifetime_neighbor(void)
@@ -296,3 +295,4 @@ uip_ds6_get_least_lifetime_neighbor(void)
   }
   return nbr_expiring;
 }
+/*---------------------------------------------------------------------------*/
diff --git a/core/net/uip-ds6-nbr.h b/core/net/uip-ds6-nbr.h
index 18251e189..059162710 100644
--- a/core/net/uip-ds6-nbr.h
+++ b/core/net/uip-ds6-nbr.h
@@ -83,15 +83,15 @@ typedef struct uip_ds6_nbr {
 void uip_ds6_neighbors_init(void);
 
 /** \brief Neighbor Cache basic routines */
-uip_ds6_nbr_t *uip_ds6_nbr_add(uip_ipaddr_t *ipaddr, uip_lladdr_t *lladdr,
+uip_ds6_nbr_t *uip_ds6_nbr_add(const uip_ipaddr_t *ipaddr, const uip_lladdr_t *lladdr,
                                uint8_t isrouter, uint8_t state);
 void uip_ds6_nbr_rm(uip_ds6_nbr_t *nbr);
-uip_lladdr_t *uip_ds6_nbr_get_ll(uip_ds6_nbr_t *nbr);
-uip_ipaddr_t *uip_ds6_nbr_get_ipaddr(uip_ds6_nbr_t *nbr);
-uip_ds6_nbr_t *uip_ds6_nbr_lookup(uip_ipaddr_t *ipaddr);
-uip_ds6_nbr_t *uip_ds6_nbr_ll_lookup(uip_lladdr_t *lladdr);
-uip_ipaddr_t *uip_ds6_nbr_ipaddr_from_lladdr(uip_lladdr_t *lladdr);
-uip_lladdr_t *uip_ds6_nbr_lladdr_from_ipaddr(uip_ipaddr_t *ipaddr);
+const uip_lladdr_t *uip_ds6_nbr_get_ll(const uip_ds6_nbr_t *nbr);
+const uip_ipaddr_t *uip_ds6_nbr_get_ipaddr(const uip_ds6_nbr_t *nbr);
+uip_ds6_nbr_t *uip_ds6_nbr_lookup(const uip_ipaddr_t *ipaddr);
+uip_ds6_nbr_t *uip_ds6_nbr_ll_lookup(const uip_lladdr_t *lladdr);
+uip_ipaddr_t *uip_ds6_nbr_ipaddr_from_lladdr(const uip_lladdr_t *lladdr);
+const uip_lladdr_t *uip_ds6_nbr_lladdr_from_ipaddr(const uip_ipaddr_t *ipaddr);
 void uip_ds6_link_neighbor_callback(int status, int numtx);
 void uip_ds6_neighbor_periodic(void);
 int uip_ds6_nbr_num(void);
diff --git a/core/net/uip-ds6-route.c b/core/net/uip-ds6-route.c
index 917ee266e..137191f55 100644
--- a/core/net/uip-ds6-route.c
+++ b/core/net/uip-ds6-route.c
@@ -261,7 +261,7 @@ uip_ds6_route_add(uip_ipaddr_t *ipaddr, uint8_t length,
 #endif /* DEBUG != DEBUG_NONE */
 
   /* Get link-layer address of next hop, make sure it is in neighbor table */
-  uip_lladdr_t *nexthop_lladdr = uip_ds6_nbr_lladdr_from_ipaddr(nexthop);
+  const uip_lladdr_t *nexthop_lladdr = uip_ds6_nbr_lladdr_from_ipaddr(nexthop);
   if(nexthop_lladdr == NULL) {
     PRINTF("uip_ds6_route_add: neighbor link-local address unknown ");
     PRINT6ADDR(ipaddr);
@@ -440,7 +440,7 @@ void
 uip_ds6_route_rm_by_nexthop(uip_ipaddr_t *nexthop)
 {
   /* Get routing entry list of this neighbor */
-  uip_lladdr_t *nexthop_lladdr;
+  const uip_lladdr_t *nexthop_lladdr;
   struct uip_ds6_route_neighbor_routes *routes;
 
   nexthop_lladdr = uip_ds6_nbr_lladdr_from_ipaddr(nexthop);
diff --git a/core/net/uip-nd6.c b/core/net/uip-nd6.c
index 85b7e6154..4c9c1b775 100644
--- a/core/net/uip-nd6.c
+++ b/core/net/uip-nd6.c
@@ -191,7 +191,7 @@ uip_nd6_ns_input(void)
 			  (uip_lladdr_t *)&nd6_opt_llao[UIP_ND6_OPT_DATA_OFFSET],
 			  0, NBR_STALE);
         } else {
-          uip_lladdr_t *lladdr = uip_ds6_nbr_get_ll(nbr);
+          uip_lladdr_t *lladdr = (uip_lladdr_t *)uip_ds6_nbr_get_ll(nbr);
           if(memcmp(&nd6_opt_llao[UIP_ND6_OPT_DATA_OFFSET],
 		    lladdr, UIP_LLADDR_LEN) != 0) {
             memcpy(lladdr, &nd6_opt_llao[UIP_ND6_OPT_DATA_OFFSET],
@@ -463,7 +463,7 @@ uip_nd6_na_input(void)
   } else {
     uip_lladdr_t *lladdr;
     nbr = uip_ds6_nbr_lookup(&UIP_ND6_NA_BUF->tgtipaddr);
-    lladdr = uip_ds6_nbr_get_ll(nbr);
+    lladdr = (uip_lladdr_t *)uip_ds6_nbr_get_ll(nbr);
     if(nbr == NULL) {
       goto discard;
     }
diff --git a/examples/ravenusbstick/fakeuip.c b/examples/ravenusbstick/fakeuip.c
index f7d4fff81..a1e980aab 100644
--- a/examples/ravenusbstick/fakeuip.c
+++ b/examples/ravenusbstick/fakeuip.c
@@ -25,14 +25,14 @@ void tcpip_input( void )
   mac_LowpanToEthernet();
 }
 
-uint8_t tcpip_output(uip_lladdr_t * lladdr){
+uint8_t tcpip_output(const uip_lladdr_t * lladdr){
   if(output != NULL) {
     return output(lladdr);
   }
  return 0;
 }
 //Called from  sicslowpan.c
-void tcpip_set_outputfunc(uint8_t (* f)(uip_lladdr_t *)) {
+void tcpip_set_outputfunc(uint8_t (* f)(const uip_lladdr_t *)) {
   output = f;
 }
 

From 469884171a100197de264e6bf4cc5d182bab129a Mon Sep 17 00:00:00 2001
From: Adam Dunkels <adam@thingsquare.com>
Date: Mon, 18 Nov 2013 23:26:37 +0100
Subject: [PATCH 2/2] Added the const keyword to functions that use the
 tcpip_set_outputfunc(), which now takes a const argument

---
 cpu/native/net/tapdev6.c                   | 5 +++--
 cpu/native/net/tapdev6.h                   | 2 +-
 cpu/native/net/wpcap.c                     | 6 +++---
 cpu/native/net/wpcap.h                     | 4 ++--
 tools/sky/uip6-bridge/uip6-bridge-tap.c    | 6 +++---
 tools/stm32w/uip6_bridge/uip6-bridge-tap.c | 6 +++---
 6 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/cpu/native/net/tapdev6.c b/cpu/native/net/tapdev6.c
index 71a250792..22815dd42 100644
--- a/cpu/native/net/tapdev6.c
+++ b/cpu/native/net/tapdev6.c
@@ -98,7 +98,7 @@ static unsigned long lasttime;
 #endif
 
 static void do_send(void);
-uint8_t tapdev_send(uip_lladdr_t *lladdr);
+uint8_t tapdev_send(const uip_lladdr_t *lladdr);
 
 /*---------------------------------------------------------------------------*/
 int
@@ -371,7 +371,8 @@ do_send(void)
   }
 }
 /*---------------------------------------------------------------------------*/
-uint8_t tapdev_send(uip_lladdr_t *lladdr)
+uint8_t
+tapdev_send(const uip_lladdr_t *lladdr)
 {
   /*
    * If L3 dest is multicast, build L2 multicast address
diff --git a/cpu/native/net/tapdev6.h b/cpu/native/net/tapdev6.h
index 4e7fe0f63..5fbd2f9bd 100644
--- a/cpu/native/net/tapdev6.h
+++ b/cpu/native/net/tapdev6.h
@@ -39,7 +39,7 @@
 #include "contiki-net.h"
 
 void tapdev_init(void);
-uint8_t tapdev_send(uip_lladdr_t *lladdr);
+uint8_t tapdev_send(const uip_lladdr_t *lladdr);
 uint16_t tapdev_poll(void);
 void tapdev_do_send(void);
 void tapdev_exit(void); //math
diff --git a/cpu/native/net/wpcap.c b/cpu/native/net/wpcap.c
index 062cc476b..ddb698a05 100644
--- a/cpu/native/net/wpcap.c
+++ b/cpu/native/net/wpcap.c
@@ -185,7 +185,7 @@ init(void)
 /* Nothing to do here */
 }
 /*---------------------------------------------------------------------------*/
-uint8_t wfall_send(uip_lladdr_t *lladdr);
+uint8_t wfall_send(const uip_lladdr_t *lladdr);
 #if FALLBACK_HAS_ETHERNET_HEADERS
 #undef IPBUF
 #define IPBUF ((struct uip_tcpip_hdr *)&uip_buf[14])
@@ -708,7 +708,7 @@ wfall_poll(void)
 /*---------------------------------------------------------------------------*/
 #if UIP_CONF_IPV6
 uint8_t
-wpcap_send(uip_lladdr_t *lladdr)
+wpcap_send(const uip_lladdr_t *lladdr)
 {
   if(lladdr == NULL) {
 /* the dest must be multicast*/
@@ -745,7 +745,7 @@ return 0;
 }
 #ifdef UIP_FALLBACK_INTERFACE
 uint8_t
-wfall_send(uip_lladdr_t *lladdr)
+wfall_send(const uip_lladdr_t *lladdr)
 {
 #if FALLBACK_HAS_ETHERNET_HEADERS
 	//make room for ethernet header
diff --git a/cpu/native/net/wpcap.h b/cpu/native/net/wpcap.h
index e5b641f88..04a8ca0a7 100644
--- a/cpu/native/net/wpcap.h
+++ b/cpu/native/net/wpcap.h
@@ -39,8 +39,8 @@ void wpcap_init(void);
 uint16_t wpcap_poll(void);
 uint16_t wfall_poll(void);
 #if UIP_CONF_IPV6
-uint8_t wpcap_send(uip_lladdr_t *lladdr);
-uint8_t wfall_send(uip_lladdr_t *lladdr);
+uint8_t wpcap_send(const uip_lladdr_t *lladdr);
+uint8_t wfall_send(const uip_lladdr_t *lladdr);
 #else
 void wpcap_send(void);
 #endif
diff --git a/tools/sky/uip6-bridge/uip6-bridge-tap.c b/tools/sky/uip6-bridge/uip6-bridge-tap.c
index 64c9f6cf7..375c5e045 100644
--- a/tools/sky/uip6-bridge/uip6-bridge-tap.c
+++ b/tools/sky/uip6-bridge/uip6-bridge-tap.c
@@ -55,9 +55,9 @@ PROCESS(tcpip_process, "tcpip dummy");
 AUTOSTART_PROCESSES(&uip6_bridge);
 
 /*---------------------------------------------------------------------------*/
-static uint8_t (* outputfunc)(uip_lladdr_t *a);
+static uint8_t (* outputfunc)(const uip_lladdr_t *a);
 uint8_t
-tcpip_output(uip_lladdr_t *a)
+tcpip_output(const uip_lladdr_t *a)
 {
   if(outputfunc != NULL) {
     outputfunc(a);
@@ -73,7 +73,7 @@ tcpip_ipv6_output(void)
 {
 }
 void
-tcpip_set_outputfunc(uint8_t (*f)(uip_lladdr_t *))
+tcpip_set_outputfunc(uint8_t (*f)(const uip_lladdr_t *))
 {
   outputfunc = f;
 }
diff --git a/tools/stm32w/uip6_bridge/uip6-bridge-tap.c b/tools/stm32w/uip6_bridge/uip6-bridge-tap.c
index 0f9da30ee..e5d2cb695 100644
--- a/tools/stm32w/uip6_bridge/uip6-bridge-tap.c
+++ b/tools/stm32w/uip6_bridge/uip6-bridge-tap.c
@@ -57,9 +57,9 @@ PROCESS(tcpip_process, "tcpip dummy");
 AUTOSTART_PROCESSES(&uip6_bridge);
 
 /*---------------------------------------------------------------------------*/
-static uint8_t (* outputfunc)(uip_lladdr_t *a);
+static uint8_t (* outputfunc)(const uip_lladdr_t *a);
 uint8_t
-tcpip_output(uip_lladdr_t *a)
+tcpip_output(const uip_lladdr_t *a)
 {
   if(outputfunc != NULL) {
     leds_on(LEDS_GREEN);
@@ -76,7 +76,7 @@ tcpip_ipv6_output(void)
 {
 }
 void
-tcpip_set_outputfunc(uint8_t (*f)(uip_lladdr_t *))
+tcpip_set_outputfunc(uint8_t (*f)(const uip_lladdr_t *))
 {
   outputfunc = f;
 }