new file mode 100644
--- /dev/null
+++ b/src/core/ngx_radix_tree.c
@@ -0,0 +1,152 @@
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+/* STUB: page size */
+#define NGX_RADIX_TREE_POOL_SIZE  4096
+
+
+static void *ngx_radix_alloc(ngx_radix_tree_t *tree, size_t size);
+
+
+ngx_radix_tree_t *ngx_radix_tree_create(ngx_pool_t *pool)
+{
+    ngx_radix_tree_t  *tree;
+
+    if (!(tree = ngx_palloc(pool, sizeof(ngx_radix_tree_t)))) {
+        return NULL;
+    }
+
+    tree->root = NULL;
+    tree->pool = pool;
+    tree->free = NULL;
+    tree->size = 0;
+
+    return tree;
+}
+
+
+ngx_int_t ngx_radix32tree_insert(ngx_radix_tree_t *tree,
+                                 uint32_t key, uint32_t mask, uintptr_t value)
+{
+    uint32_t           bit;
+    ngx_radix_node_t  *node, *new;
+
+    bit = 0x80000000;
+    node = tree->root;
+
+    while (node && (bit & mask)) {
+        if (key & bit) {
+            node = node->right;
+
+        } else {
+            node = node->left;
+        }
+
+        bit >>= 1;
+    }
+
+    if (node) {
+        if (node->value) {
+            return NGX_BUSY;
+        }
+
+        node->value = value;
+        return NGX_OK;
+    }
+
+    while (bit & mask) {
+        if (!(new = ngx_radix_alloc(tree, sizeof(ngx_radix_node_t)))) {
+            return NGX_ERROR;
+        }
+
+        new->value = value;
+
+        if (key & bit) {
+            node->right = new;
+
+        } else {
+            node->left = new;
+        }
+
+        bit >>= 1;
+        new = node;
+    }
+
+    return NGX_OK;
+}
+
+
+void ngx_radix32tree_delete(ngx_radix_tree_t *tree, uint32_t key, uint32_t mask)
+{
+    uint32_t           bit;
+    ngx_radix_node_t  *node;
+
+    bit = 0x80000000;
+    node = tree->root;
+
+    while (node && (bit & mask)) {
+        if (key & bit) {
+            node = node->right;
+
+        } else {
+            node = node->left;
+        }
+
+        bit >>= 1;
+    }
+
+    if (node) {
+        node->value = (uintptr_t) 0;
+    }
+}
+
+
+uintptr_t ngx_radix32tree_find(ngx_radix_tree_t *tree, uint32_t key)
+{
+    uint32_t           bit;
+    uintptr_t          value;
+    ngx_radix_node_t  *node;
+
+    bit = 0x80000000;
+    value = NULL;
+    node = tree->root;
+
+    while (node) {
+        if (node->value) {
+            value = node->value;
+        }
+
+        if (key & bit) {
+            node = node->right;
+
+        } else {
+            node = node->left;
+        }
+
+        bit >>= 1;
+    }
+
+    return value;
+}
+
+
+static void *ngx_radix_alloc(ngx_radix_tree_t *tree, size_t size)
+{
+    char  *p;
+
+    if (tree->size < size) {
+        if (!(tree->free = ngx_palloc(tree->pool, NGX_RADIX_TREE_POOL_SIZE))) {
+            return NULL;
+        }
+
+        tree->size = NGX_RADIX_TREE_POOL_SIZE;
+    }
+
+    p = tree->free;
+    tree->free += size;
+    tree->size -= size;
+
+    return p;
+}