use lwip memp pools for allocating coap_queue_t

lwippools.h

@@ -0,0 +1,13 @@
+/** Memory pool definitions for the libcoap when used with lwIP (which has its
+ * own mechanism for quickly allocating chunks of data with known sizes). Has
+ * to be findable by lwIP (ie. an #include <lwippools.h> must either directly
+ * include this or include something more generic which includes this), and
+ * MEMP_USE_CUSTOM_POOLS has to be set in lwipopts.h. */
+
+#include <net.h>
+
+#ifndef MEMP_NUM_COAPNODE
+#define MEMP_NUM_COAPNODE 4
+#endif
+
+LWIP_MEMPOOL(COAP_NODE, MEMP_NUM_COAPNODE, sizeof(coap_queue_t), "COAP_NODE")

net.c

@@ -40,9 +40,7 @@
 #include "encode.h"
 #include "net.h"
 
-#if defined(WITH_POSIX) || defined(WITH_LWIP)
-
-/* FIXME: in lwip, we'll use pbufs later */
+#if defined(WITH_POSIX)
 
 time_t clock_offset;
 
@@ -55,7 +53,24 @@ static inline void
 coap_free_node(coap_queue_t *node) {
   coap_free(node);
 }
-#endif /* WITH_POSIX || WITH_LWIP */
+#endif /* WITH_POSIX */
+#ifdef WITH_LWIP
+
+#include <lwip/memp.h>
+
+time_t clock_offset; /* FIXME timing is currently ignored */
+
+static inline coap_queue_t *
+coap_malloc_node() {
+	return (coap_queue_t *)memp_malloc(MEMP_COAP_NODE);
+}
+
+static inline void
+coap_free_node(coap_queue_t *node) {
+	memp_free(MEMP_COAP_NODE, node);
+}
+
+#endif /* WITH_LWIP */
 #ifdef WITH_CONTIKI
 # ifndef DEBUG
 #  define DEBUG DEBUG_PRINT