[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit

Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/app/iptables/libiptc/libiptc.c b/ap/app/iptables/libiptc/libiptc.c
new file mode 100755
index 0000000..4c3437e
--- /dev/null
+++ b/ap/app/iptables/libiptc/libiptc.c
@@ -0,0 +1,2765 @@
+/* Library which manipulates firewall rules.  Version $Revision$ */
+
+/* Architecture of firewall rules is as follows:
+ *
+ * Chains go INPUT, FORWARD, OUTPUT then user chains.
+ * Each user chain starts with an ERROR node.
+ * Every chain ends with an unconditional jump: a RETURN for user chains,
+ * and a POLICY for built-ins.
+ */
+
+/* (C) 1999 Paul ``Rusty'' Russell - Placed under the GNU GPL (See
+ * COPYING for details).
+ * (C) 2000-2004 by the Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * 2003-Jun-20: Harald Welte <laforge@netfilter.org>:
+ *	- Reimplementation of chain cache to use offsets instead of entries
+ * 2003-Jun-23: Harald Welte <laforge@netfilter.org>:
+ * 	- performance optimization, sponsored by Astaro AG (http://www.astaro.com/)
+ * 	  don't rebuild the chain cache after every operation, instead fix it
+ * 	  up after a ruleset change.
+ * 2004-Aug-18: Harald Welte <laforge@netfilter.org>:
+ * 	- further performance work: total reimplementation of libiptc.
+ * 	- libiptc now has a real internal (linked-list) represntation of the
+ * 	  ruleset and a parser/compiler from/to this internal representation
+ * 	- again sponsored by Astaro AG (http://www.astaro.com/)
+ *
+ * 2008-Jan+Jul: Jesper Dangaard Brouer <hawk@comx.dk>
+ * 	- performance work: speedup chain list "name" searching.
+ * 	- performance work: speedup initial ruleset parsing.
+ * 	- sponsored by ComX Networks A/S (http://www.comx.dk/)
+ */
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <xtables.h>
+
+#include "linux_list.h"
+
+//#define IPTC_DEBUG2 1
+
+#ifdef IPTC_DEBUG2
+#include <fcntl.h>
+#define DEBUGP(x, args...)	fprintf(stderr, "%s: " x, __FUNCTION__, ## args)
+#define DEBUGP_C(x, args...)	fprintf(stderr, x, ## args)
+#else
+#define DEBUGP(x, args...)
+#define DEBUGP_C(x, args...)
+#endif
+
+#ifdef DEBUG
+#define debug(x, args...)	fprintf(stderr, x, ## args)
+#else
+#define debug(x, args...)
+#endif
+
+static void *iptc_fn = NULL;
+
+static const char *hooknames[] = {
+	[HOOK_PRE_ROUTING]	= "PREROUTING",
+	[HOOK_LOCAL_IN]		= "INPUT",
+	[HOOK_FORWARD]		= "FORWARD",
+	[HOOK_LOCAL_OUT]	= "OUTPUT",
+	[HOOK_POST_ROUTING]	= "POSTROUTING",
+#ifdef HOOK_DROPPING
+	[HOOK_DROPPING]		= "DROPPING"
+#endif
+};
+
+/* Convenience structures */
+struct ipt_error_target
+{
+	STRUCT_ENTRY_TARGET t;
+	char error[TABLE_MAXNAMELEN];
+};
+
+struct chain_head;
+struct rule_head;
+
+struct counter_map
+{
+	enum {
+		COUNTER_MAP_NOMAP,
+		COUNTER_MAP_NORMAL_MAP,
+		COUNTER_MAP_ZEROED,
+		COUNTER_MAP_SET
+	} maptype;
+	unsigned int mappos;
+};
+
+enum iptcc_rule_type {
+	IPTCC_R_STANDARD,		/* standard target (ACCEPT, ...) */
+	IPTCC_R_MODULE,			/* extension module (SNAT, ...) */
+	IPTCC_R_FALLTHROUGH,		/* fallthrough rule */
+	IPTCC_R_JUMP,			/* jump to other chain */
+};
+
+struct rule_head
+{
+	struct list_head list;
+	struct chain_head *chain;
+	struct counter_map counter_map;
+
+	unsigned int index;		/* index (needed for counter_map) */
+	unsigned int offset;		/* offset in rule blob */
+
+	enum iptcc_rule_type type;
+	struct chain_head *jump;	/* jump target, if IPTCC_R_JUMP */
+
+	unsigned int size;		/* size of entry data */
+	STRUCT_ENTRY entry[0];
+};
+
+struct chain_head
+{
+	struct list_head list;
+	char name[TABLE_MAXNAMELEN];
+	unsigned int hooknum;		/* hook number+1 if builtin */
+	unsigned int references;	/* how many jumps reference us */
+	int verdict;			/* verdict if builtin */
+
+	STRUCT_COUNTERS counters;	/* per-chain counters */
+	struct counter_map counter_map;
+
+	unsigned int num_rules;		/* number of rules in list */
+	struct list_head rules;		/* list of rules */
+
+	unsigned int index;		/* index (needed for jump resolval) */
+	unsigned int head_offset;	/* offset in rule blob */
+	unsigned int foot_index;	/* index (needed for counter_map) */
+	unsigned int foot_offset;	/* offset in rule blob */
+};
+
+STRUCT_TC_HANDLE
+{
+	int sockfd;
+	int changed;			 /* Have changes been made? */
+
+	struct list_head chains;
+
+	struct chain_head *chain_iterator_cur;
+	struct rule_head *rule_iterator_cur;
+
+	unsigned int num_chains;         /* number of user defined chains */
+
+	struct chain_head **chain_index;   /* array for fast chain list access*/
+	unsigned int        chain_index_sz;/* size of chain index array */
+
+	int sorted_offsets; /* if chains are received sorted from kernel,
+			     * then the offsets are also sorted. Says if its
+			     * possible to bsearch offsets using chain_index.
+			     */
+
+	STRUCT_GETINFO info;
+	STRUCT_GET_ENTRIES *entries;
+};
+
+enum bsearch_type {
+	BSEARCH_NAME,	/* Binary search after chain name */
+	BSEARCH_OFFSET,	/* Binary search based on offset */
+};
+
+/* allocate a new chain head for the cache */
+static struct chain_head *iptcc_alloc_chain_head(const char *name, int hooknum)
+{
+	struct chain_head *c = malloc(sizeof(*c));
+	if (!c)
+		return NULL;
+	memset(c, 0, sizeof(*c));
+
+	strncpy(c->name, name, TABLE_MAXNAMELEN);
+	c->hooknum = hooknum;
+	INIT_LIST_HEAD(&c->rules);
+
+	return c;
+}
+
+/* allocate and initialize a new rule for the cache */
+static struct rule_head *iptcc_alloc_rule(struct chain_head *c, unsigned int size)
+{
+	struct rule_head *r = malloc(sizeof(*r)+size);
+	if (!r)
+		return NULL;
+	memset(r, 0, sizeof(*r));
+
+	r->chain = c;
+	r->size = size;
+
+	return r;
+}
+
+/* notify us that the ruleset has been modified by the user */
+static inline void
+set_changed(struct xtc_handle *h)
+{
+	h->changed = 1;
+}
+
+#ifdef IPTC_DEBUG
+static void do_check(struct xtc_handle *h, unsigned int line);
+#define CHECK(h) do { if (!getenv("IPTC_NO_CHECK")) do_check((h), __LINE__); } while(0)
+#else
+#define CHECK(h)
+#endif
+
+
+/**********************************************************************
+ * iptc blob utility functions (iptcb_*)
+ **********************************************************************/
+
+static inline int
+iptcb_get_number(const STRUCT_ENTRY *i,
+	   const STRUCT_ENTRY *seek,
+	   unsigned int *pos)
+{
+	if (i == seek)
+		return 1;
+	(*pos)++;
+	return 0;
+}
+
+static inline int
+iptcb_get_entry_n(STRUCT_ENTRY *i,
+	    unsigned int number,
+	    unsigned int *pos,
+	    STRUCT_ENTRY **pe)
+{
+	if (*pos == number) {
+		*pe = i;
+		return 1;
+	}
+	(*pos)++;
+	return 0;
+}
+
+static inline STRUCT_ENTRY *
+iptcb_get_entry(struct xtc_handle *h, unsigned int offset)
+{
+	return (STRUCT_ENTRY *)((char *)h->entries->entrytable + offset);
+}
+
+static unsigned int
+iptcb_entry2index(struct xtc_handle *const h, const STRUCT_ENTRY *seek)
+{
+	unsigned int pos = 0;
+
+	if (ENTRY_ITERATE(h->entries->entrytable, h->entries->size,
+			  iptcb_get_number, seek, &pos) == 0) {
+		fprintf(stderr, "ERROR: offset %u not an entry!\n",
+			(unsigned int)((char *)seek - (char *)h->entries->entrytable));
+		abort();
+	}
+	return pos;
+}
+
+static inline STRUCT_ENTRY *
+iptcb_offset2entry(struct xtc_handle *h, unsigned int offset)
+{
+	return (STRUCT_ENTRY *) ((void *)h->entries->entrytable+offset);
+}
+
+
+static inline unsigned long
+iptcb_entry2offset(struct xtc_handle *const h, const STRUCT_ENTRY *e)
+{
+	return (void *)e - (void *)h->entries->entrytable;
+}
+
+static inline unsigned int
+iptcb_offset2index(struct xtc_handle *const h, unsigned int offset)
+{
+	return iptcb_entry2index(h, iptcb_offset2entry(h, offset));
+}
+
+/* Returns 0 if not hook entry, else hooknumber + 1 */
+static inline unsigned int
+iptcb_ent_is_hook_entry(STRUCT_ENTRY *e, struct xtc_handle *h)
+{
+	unsigned int i;
+
+	for (i = 0; i < NUMHOOKS; i++) {
+		if ((h->info.valid_hooks & (1 << i))
+		    && iptcb_get_entry(h, h->info.hook_entry[i]) == e)
+			return i+1;
+	}
+	return 0;
+}
+
+
+/**********************************************************************
+ * Chain index (cache utility) functions
+ **********************************************************************
+ * The chain index is an array with pointers into the chain list, with
+ * CHAIN_INDEX_BUCKET_LEN spacing.  This facilitates the ability to
+ * speedup chain list searching, by find a more optimal starting
+ * points when searching the linked list.
+ *
+ * The starting point can be found fast by using a binary search of
+ * the chain index. Thus, reducing the previous search complexity of
+ * O(n) to O(log(n/k) + k) where k is CHAIN_INDEX_BUCKET_LEN.
+ *
+ * A nice property of the chain index, is that the "bucket" list
+ * length is max CHAIN_INDEX_BUCKET_LEN (when just build, inserts will
+ * change this). Oppose to hashing, where the "bucket" list length can
+ * vary a lot.
+ */
+#ifndef CHAIN_INDEX_BUCKET_LEN
+#define CHAIN_INDEX_BUCKET_LEN 40
+#endif
+
+/* Another nice property of the chain index is that inserting/creating
+ * chains in chain list don't change the correctness of the chain
+ * index, it only causes longer lists in the buckets.
+ *
+ * To mitigate the performance penalty of longer bucket lists and the
+ * penalty of rebuilding, the chain index is rebuild only when
+ * CHAIN_INDEX_INSERT_MAX chains has been added.
+ */
+#ifndef CHAIN_INDEX_INSERT_MAX
+#define CHAIN_INDEX_INSERT_MAX 355
+#endif
+
+static inline unsigned int iptcc_is_builtin(struct chain_head *c);
+
+/* Use binary search in the chain index array, to find a chain_head
+ * pointer closest to the place of the searched name element.
+ *
+ * Notes that, binary search (obviously) requires that the chain list
+ * is sorted by name.
+ *
+ * The not so obvious: The chain index array, is actually both sorted
+ * by name and offset, at the same time!.  This is only true because,
+ * chain are stored sorted in the kernel (as we pushed it in sorted).
+ *
+ */
+static struct list_head *
+__iptcc_bsearch_chain_index(const char *name, unsigned int offset,
+			    unsigned int *idx, struct xtc_handle *handle,
+			    enum bsearch_type type)
+{
+	unsigned int pos, end;
+	int res;
+
+	struct list_head *list_pos;
+	list_pos=&handle->chains;
+
+	/* Check for empty array, e.g. no user defined chains */
+	if (handle->chain_index_sz == 0) {
+		debug("WARNING: handle->chain_index_sz == 0\n");
+		return list_pos;
+	}
+
+	/* Init */
+	end = handle->chain_index_sz;
+	pos = end / 2;
+
+	debug("bsearch Find chain:%s (pos:%d end:%d) (offset:%d)\n",
+	      name, pos, end, offset);
+
+	/* Loop */
+ loop:
+	if (!handle->chain_index[pos]) {
+		fprintf(stderr, "ERROR: NULL pointer chain_index[%d]\n", pos);
+		return &handle->chains; /* Be safe, return orig start pos */
+	}
+
+	debug("bsearch Index[%d] name:%s ",
+	      pos, handle->chain_index[pos]->name);
+
+	/* Support for different compare functions */
+	switch (type) {
+	case BSEARCH_NAME:
+		res = strcmp(name, handle->chain_index[pos]->name);
+		break;
+	case BSEARCH_OFFSET:
+		debug("head_offset:[%d] foot_offset:[%d] ",
+		      handle->chain_index[pos]->head_offset,
+		      handle->chain_index[pos]->foot_offset);
+		res = offset - handle->chain_index[pos]->head_offset;
+		break;
+	default:
+		fprintf(stderr, "ERROR: %d not a valid bsearch type\n",
+			type);
+		abort();
+		break;
+	}
+	debug("res:%d ", res);
+
+
+	list_pos = &handle->chain_index[pos]->list;
+	*idx = pos;
+
+	if (res == 0) { /* Found element, by direct hit */
+		debug("[found] Direct hit pos:%d end:%d\n", pos, end);
+		return list_pos;
+	} else if (res < 0) { /* Too far, jump back */
+		end = pos;
+		pos = pos / 2;
+
+		/* Exit case: First element of array */
+		if (end == 0) {
+			debug("[found] Reached first array elem (end%d)\n",end);
+			return list_pos;
+		}
+		debug("jump back to pos:%d (end:%d)\n", pos, end);
+		goto loop;
+	} else if (res > 0 ){ /* Not far enough, jump forward */
+
+		/* Exit case: Last element of array */
+		if (pos == handle->chain_index_sz-1) {
+			debug("[found] Last array elem (end:%d)\n", end);
+			return list_pos;
+		}
+
+		/* Exit case: Next index less, thus elem in this list section */
+		switch (type) {
+		case BSEARCH_NAME:
+			res = strcmp(name, handle->chain_index[pos+1]->name);
+			break;
+		case BSEARCH_OFFSET:
+			res = offset - handle->chain_index[pos+1]->head_offset;
+			break;
+		}
+
+		if (res < 0) {
+			debug("[found] closest list (end:%d)\n", end);
+			return list_pos;
+		}
+
+		pos = (pos+end)/2;
+		debug("jump forward to pos:%d (end:%d)\n", pos, end);
+		goto loop;
+	}
+
+	return list_pos;
+}
+
+/* Wrapper for string chain name based bsearch */
+static struct list_head *
+iptcc_bsearch_chain_index(const char *name, unsigned int *idx,
+			  struct xtc_handle *handle)
+{
+	return __iptcc_bsearch_chain_index(name, 0, idx, handle, BSEARCH_NAME);
+}
+
+
+/* Wrapper for offset chain based bsearch */
+static struct list_head *
+iptcc_bsearch_chain_offset(unsigned int offset, unsigned int *idx,
+			  struct xtc_handle *handle)
+{
+	struct list_head *pos;
+
+	/* If chains were not received sorted from kernel, then the
+	 * offset bsearch is not possible.
+	 */
+	if (!handle->sorted_offsets)
+		pos = handle->chains.next;
+	else
+		pos = __iptcc_bsearch_chain_index(NULL, offset, idx, handle,
+						  BSEARCH_OFFSET);
+	return pos;
+}
+
+
+#ifdef DEBUG
+/* Trivial linear search of chain index. Function used for verifying
+   the output of bsearch function */
+static struct list_head *
+iptcc_linearly_search_chain_index(const char *name, struct xtc_handle *handle)
+{
+	unsigned int i=0;
+	int res=0;
+
+	struct list_head *list_pos;
+	list_pos = &handle->chains;
+
+	if (handle->chain_index_sz)
+		list_pos = &handle->chain_index[0]->list;
+
+	/* Linearly walk of chain index array */
+
+	for (i=0; i < handle->chain_index_sz; i++) {
+		if (handle->chain_index[i]) {
+			res = strcmp(handle->chain_index[i]->name, name);
+			if (res > 0)
+				break; // One step too far
+			list_pos = &handle->chain_index[i]->list;
+			if (res == 0)
+				break; // Direct hit
+		}
+	}
+
+	return list_pos;
+}
+#endif
+
+static int iptcc_chain_index_alloc(struct xtc_handle *h)
+{
+	unsigned int list_length = CHAIN_INDEX_BUCKET_LEN;
+	unsigned int array_elems;
+	unsigned int array_mem;
+
+	/* Allocate memory for the chain index array */
+	array_elems = (h->num_chains / list_length) +
+                      (h->num_chains % list_length ? 1 : 0);
+	array_mem   = sizeof(h->chain_index) * array_elems;
+
+	debug("Alloc Chain index, elems:%d mem:%d bytes\n",
+	      array_elems, array_mem);
+
+	h->chain_index = malloc(array_mem);
+	if (h->chain_index == NULL && array_mem > 0) {
+		h->chain_index_sz = 0;
+		return -ENOMEM;
+	}
+	memset(h->chain_index, 0, array_mem);
+	h->chain_index_sz = array_elems;
+
+	return 1;
+}
+
+static void iptcc_chain_index_free(struct xtc_handle *h)
+{
+	h->chain_index_sz = 0;
+	free(h->chain_index);
+}
+
+
+#ifdef DEBUG
+static void iptcc_chain_index_dump(struct xtc_handle *h)
+{
+	unsigned int i = 0;
+
+	/* Dump: contents of chain index array */
+	for (i=0; i < h->chain_index_sz; i++) {
+		if (h->chain_index[i]) {
+			fprintf(stderr, "Chain index[%d].name: %s\n",
+				i, h->chain_index[i]->name);
+		}
+	}
+}
+#endif
+
+/* Build the chain index */
+static int iptcc_chain_index_build(struct xtc_handle *h)
+{
+	unsigned int list_length = CHAIN_INDEX_BUCKET_LEN;
+	unsigned int chains = 0;
+	unsigned int cindex = 0;
+	struct chain_head *c;
+
+	/* Build up the chain index array here */
+	debug("Building chain index\n");
+
+	debug("Number of user defined chains:%d bucket_sz:%d array_sz:%d\n",
+		h->num_chains, list_length, h->chain_index_sz);
+
+	if (h->chain_index_sz == 0)
+		return 0;
+
+	list_for_each_entry(c, &h->chains, list) {
+
+		/* Issue: The index array needs to start after the
+		 * builtin chains, as they are not sorted */
+		if (!iptcc_is_builtin(c)) {
+			cindex=chains / list_length;
+
+			/* Safe guard, break out on array limit, this
+			 * is useful if chains are added and array is
+			 * rebuild, without realloc of memory. */
+			if (cindex >= h->chain_index_sz)
+				break;
+
+			if ((chains % list_length)== 0) {
+				debug("\nIndex[%d] Chains:", cindex);
+				h->chain_index[cindex] = c;
+			}
+			chains++;
+		}
+		debug("%s, ", c->name);
+	}
+	debug("\n");
+
+	return 1;
+}
+
+static int iptcc_chain_index_rebuild(struct xtc_handle *h)
+{
+	debug("REBUILD chain index array\n");
+	iptcc_chain_index_free(h);
+	if ((iptcc_chain_index_alloc(h)) < 0)
+		return -ENOMEM;
+	iptcc_chain_index_build(h);
+	return 1;
+}
+
+/* Delete chain (pointer) from index array.  Removing an element from
+ * the chain list only affects the chain index array, if the chain
+ * index points-to/uses that list pointer.
+ *
+ * There are different strategies, the simple and safe is to rebuild
+ * the chain index every time.  The more advanced is to update the
+ * array index to point to the next element, but that requires some
+ * house keeping and boundry checks.  The advanced is implemented, as
+ * the simple approach behaves badly when all chains are deleted
+ * because list_for_each processing will always hit the first chain
+ * index, thus causing a rebuild for every chain.
+ */
+static int iptcc_chain_index_delete_chain(struct chain_head *c, struct xtc_handle *h)
+{
+	struct list_head *index_ptr, *index_ptr2, *next;
+	struct chain_head *c2;
+	unsigned int idx, idx2;
+
+	index_ptr = iptcc_bsearch_chain_index(c->name, &idx, h);
+
+	debug("Del chain[%s] c->list:%p index_ptr:%p\n",
+	      c->name, &c->list, index_ptr);
+
+	/* Save the next pointer */
+	next = c->list.next;
+	list_del(&c->list);
+
+	if (index_ptr == &c->list) { /* Chain used as index ptr */
+
+		/* See if its possible to avoid a rebuild, by shifting
+		 * to next pointer.  Its possible if the next pointer
+		 * is located in the same index bucket.
+		 */
+		c2         = list_entry(next, struct chain_head, list);
+		index_ptr2 = iptcc_bsearch_chain_index(c2->name, &idx2, h);
+		if (idx != idx2) {
+			/* Rebuild needed */
+			return iptcc_chain_index_rebuild(h);
+		} else {
+			/* Avoiding rebuild */
+			debug("Update cindex[%d] with next ptr name:[%s]\n",
+			      idx, c2->name);
+			h->chain_index[idx]=c2;
+			return 0;
+		}
+	}
+	return 0;
+}
+
+
+/**********************************************************************
+ * iptc cache utility functions (iptcc_*)
+ **********************************************************************/
+
+/* Is the given chain builtin (1) or user-defined (0) */
+static inline unsigned int iptcc_is_builtin(struct chain_head *c)
+{
+	return (c->hooknum ? 1 : 0);
+}
+
+/* Get a specific rule within a chain */
+static struct rule_head *iptcc_get_rule_num(struct chain_head *c,
+					    unsigned int rulenum)
+{
+	struct rule_head *r;
+	unsigned int num = 0;
+
+	list_for_each_entry(r, &c->rules, list) {
+		num++;
+		if (num == rulenum)
+			return r;
+	}
+	return NULL;
+}
+
+/* Get a specific rule within a chain backwards */
+static struct rule_head *iptcc_get_rule_num_reverse(struct chain_head *c,
+					    unsigned int rulenum)
+{
+	struct rule_head *r;
+	unsigned int num = 0;
+
+	list_for_each_entry_reverse(r, &c->rules, list) {
+		num++;
+		if (num == rulenum)
+			return r;
+	}
+	return NULL;
+}
+
+/* Returns chain head if found, otherwise NULL. */
+static struct chain_head *
+iptcc_find_chain_by_offset(struct xtc_handle *handle, unsigned int offset)
+{
+	struct list_head *pos;
+	struct list_head *list_start_pos;
+	unsigned int i;
+
+	if (list_empty(&handle->chains))
+		return NULL;
+
+	/* Find a smart place to start the search */
+  	list_start_pos = iptcc_bsearch_chain_offset(offset, &i, handle);
+
+	/* Note that iptcc_bsearch_chain_offset() skips builtin
+	 * chains, but this function is only used for finding jump
+	 * targets, and a buildin chain is not a valid jump target */
+
+	debug("Offset:[%u] starting search at index:[%u]\n", offset, i);
+//	list_for_each(pos, &handle->chains) {
+	list_for_each(pos, list_start_pos->prev) {
+		struct chain_head *c = list_entry(pos, struct chain_head, list);
+		debug(".");
+		if (offset >= c->head_offset && offset <= c->foot_offset) {
+			debug("Offset search found chain:[%s]\n", c->name);
+			return c;
+		}
+	}
+
+	return NULL;
+}
+
+/* Returns chain head if found, otherwise NULL. */
+static struct chain_head *
+iptcc_find_label(const char *name, struct xtc_handle *handle)
+{
+	struct list_head *pos;
+	struct list_head *list_start_pos;
+	unsigned int i=0;
+	int res;
+
+	if (list_empty(&handle->chains))
+		return NULL;
+
+	/* First look at builtin chains */
+	list_for_each(pos, &handle->chains) {
+		struct chain_head *c = list_entry(pos, struct chain_head, list);
+		if (!iptcc_is_builtin(c))
+			break;
+		if (!strcmp(c->name, name))
+			return c;
+	}
+
+	/* Find a smart place to start the search via chain index */
+  	//list_start_pos = iptcc_linearly_search_chain_index(name, handle);
+  	list_start_pos = iptcc_bsearch_chain_index(name, &i, handle);
+
+	/* Handel if bsearch bails out early */
+	if (list_start_pos == &handle->chains) {
+		list_start_pos = pos;
+	}
+#ifdef DEBUG
+	else {
+		/* Verify result of bsearch against linearly index search */
+		struct list_head *test_pos;
+		struct chain_head *test_c, *tmp_c;
+		test_pos = iptcc_linearly_search_chain_index(name, handle);
+		if (list_start_pos != test_pos) {
+			debug("BUG in chain_index search\n");
+			test_c=list_entry(test_pos,      struct chain_head,list);
+			tmp_c =list_entry(list_start_pos,struct chain_head,list);
+			debug("Verify search found:\n");
+			debug(" Chain:%s\n", test_c->name);
+			debug("BSearch found:\n");
+			debug(" Chain:%s\n", tmp_c->name);
+			exit(42);
+		}
+	}
+#endif
+
+	/* Initial/special case, no user defined chains */
+	if (handle->num_chains == 0)
+		return NULL;
+
+	/* Start searching through the chain list */
+	list_for_each(pos, list_start_pos->prev) {
+		struct chain_head *c = list_entry(pos, struct chain_head, list);
+		res = strcmp(c->name, name);
+		debug("List search name:%s == %s res:%d\n", name, c->name, res);
+		if (res==0)
+			return c;
+
+		/* We can stop earlier as we know list is sorted */
+		if (res>0 && !iptcc_is_builtin(c)) { /* Walked too far*/
+			debug(" Not in list, walked too far, sorted list\n");
+			return NULL;
+		}
+
+		/* Stop on wrap around, if list head is reached */
+		if (pos == &handle->chains) {
+			debug("Stop, list head reached\n");
+			return NULL;
+		}
+	}
+
+	debug("List search NOT found name:%s\n", name);
+	return NULL;
+}
+
+/* called when rule is to be removed from cache */
+static void iptcc_delete_rule(struct rule_head *r)
+{
+	DEBUGP("deleting rule %p (offset %u)\n", r, r->offset);
+	/* clean up reference count of called chain */
+	if (r->type == IPTCC_R_JUMP
+	    && r->jump)
+		r->jump->references--;
+
+	list_del(&r->list);
+	free(r);
+}
+
+
+/**********************************************************************
+ * RULESET PARSER (blob -> cache)
+ **********************************************************************/
+
+/* Delete policy rule of previous chain, since cache doesn't contain
+ * chain policy rules.
+ * WARNING: This function has ugly design and relies on a lot of context, only
+ * to be called from specific places within the parser */
+static int __iptcc_p_del_policy(struct xtc_handle *h, unsigned int num)
+{
+	if (h->chain_iterator_cur) {
+		/* policy rule is last rule */
+		struct rule_head *pr = (struct rule_head *)
+			h->chain_iterator_cur->rules.prev;
+
+		/* save verdict */
+		h->chain_iterator_cur->verdict =
+			*(int *)GET_TARGET(pr->entry)->data;
+
+		/* save counter and counter_map information */
+		h->chain_iterator_cur->counter_map.maptype =
+						COUNTER_MAP_NORMAL_MAP;
+		h->chain_iterator_cur->counter_map.mappos = num-1;
+		memcpy(&h->chain_iterator_cur->counters, &pr->entry->counters,
+			sizeof(h->chain_iterator_cur->counters));
+
+		/* foot_offset points to verdict rule */
+		h->chain_iterator_cur->foot_index = num;
+		h->chain_iterator_cur->foot_offset = pr->offset;
+
+		/* delete rule from cache */
+		iptcc_delete_rule(pr);
+		h->chain_iterator_cur->num_rules--;
+
+		return 1;
+	}
+	return 0;
+}
+
+/* alphabetically insert a chain into the list */
+static void iptc_insert_chain(struct xtc_handle *h, struct chain_head *c)
+{
+	struct chain_head *tmp;
+	struct list_head  *list_start_pos;
+	unsigned int i=1;
+
+	/* Find a smart place to start the insert search */
+  	list_start_pos = iptcc_bsearch_chain_index(c->name, &i, h);
+
+	/* Handle the case, where chain.name is smaller than index[0] */
+	if (i==0 && strcmp(c->name, h->chain_index[0]->name) <= 0) {
+		h->chain_index[0] = c; /* Update chain index head */
+		list_start_pos = h->chains.next;
+		debug("Update chain_index[0] with %s\n", c->name);
+	}
+
+	/* Handel if bsearch bails out early */
+	if (list_start_pos == &h->chains) {
+		list_start_pos = h->chains.next;
+	}
+
+	/* sort only user defined chains */
+	if (!c->hooknum) {
+		list_for_each_entry(tmp, list_start_pos->prev, list) {
+			if (!tmp->hooknum && strcmp(c->name, tmp->name) <= 0) {
+				list_add(&c->list, tmp->list.prev);
+				return;
+			}
+
+			/* Stop if list head is reached */
+			if (&tmp->list == &h->chains) {
+				debug("Insert, list head reached add to tail\n");
+				break;
+			}
+		}
+	}
+
+	/* survived till end of list: add at tail */
+	list_add_tail(&c->list, &h->chains);
+}
+
+/* Another ugly helper function split out of cache_add_entry to make it less
+ * spaghetti code */
+static void __iptcc_p_add_chain(struct xtc_handle *h, struct chain_head *c,
+				unsigned int offset, unsigned int *num)
+{
+	struct list_head  *tail = h->chains.prev;
+	struct chain_head *ctail;
+
+	__iptcc_p_del_policy(h, *num);
+
+	c->head_offset = offset;
+	c->index = *num;
+
+	/* Chains from kernel are already sorted, as they are inserted
+	 * sorted. But there exists an issue when shifting to 1.4.0
+	 * from an older version, as old versions allow last created
+	 * chain to be unsorted.
+	 */
+	if (iptcc_is_builtin(c)) /* Only user defined chains are sorted*/
+		list_add_tail(&c->list, &h->chains);
+	else {
+		ctail = list_entry(tail, struct chain_head, list);
+
+		if (strcmp(c->name, ctail->name) > 0 ||
+		    iptcc_is_builtin(ctail))
+			list_add_tail(&c->list, &h->chains);/* Already sorted*/
+		else {
+			iptc_insert_chain(h, c);/* Was not sorted */
+
+			/* Notice, if chains were not received sorted
+			 * from kernel, then an offset bsearch is no
+			 * longer valid.
+			 */
+			h->sorted_offsets = 0;
+
+			debug("NOTICE: chain:[%s] was NOT sorted(ctail:%s)\n",
+			      c->name, ctail->name);
+		}
+	}
+
+	h->chain_iterator_cur = c;
+}
+
+/* main parser function: add an entry from the blob to the cache */
+static int cache_add_entry(STRUCT_ENTRY *e,
+			   struct xtc_handle *h,
+			   STRUCT_ENTRY **prev,
+			   unsigned int *num)
+{
+	unsigned int builtin;
+	unsigned int offset = (char *)e - (char *)h->entries->entrytable;
+
+	DEBUGP("entering...");
+
+	/* Last entry ("policy rule"). End it.*/
+	if (iptcb_entry2offset(h,e) + e->next_offset == h->entries->size) {
+		/* This is the ERROR node at the end of the chain */
+		DEBUGP_C("%u:%u: end of table:\n", *num, offset);
+
+		__iptcc_p_del_policy(h, *num);
+
+		h->chain_iterator_cur = NULL;
+		goto out_inc;
+	}
+
+	/* We know this is the start of a new chain if it's an ERROR
+	 * target, or a hook entry point */
+
+	if (strcmp(GET_TARGET(e)->u.user.name, ERROR_TARGET) == 0) {
+		struct chain_head *c =
+			iptcc_alloc_chain_head((const char *)GET_TARGET(e)->data, 0);
+		DEBUGP_C("%u:%u:new userdefined chain %s: %p\n", *num, offset,
+			(char *)c->name, c);
+		if (!c) {
+			errno = -ENOMEM;
+			return -1;
+		}
+		h->num_chains++; /* New user defined chain */
+
+		__iptcc_p_add_chain(h, c, offset, num);
+
+	} else if ((builtin = iptcb_ent_is_hook_entry(e, h)) != 0) {
+		struct chain_head *c =
+			iptcc_alloc_chain_head((char *)hooknames[builtin-1],
+						builtin);
+		DEBUGP_C("%u:%u new builtin chain: %p (rules=%p)\n",
+			*num, offset, c, &c->rules);
+		if (!c) {
+			errno = -ENOMEM;
+			return -1;
+		}
+
+		c->hooknum = builtin;
+
+		__iptcc_p_add_chain(h, c, offset, num);
+
+		/* FIXME: this is ugly. */
+		goto new_rule;
+	} else {
+		/* has to be normal rule */
+		struct rule_head *r;
+new_rule:
+
+		if (!(r = iptcc_alloc_rule(h->chain_iterator_cur,
+					   e->next_offset))) {
+			errno = ENOMEM;
+			return -1;
+		}
+		DEBUGP_C("%u:%u normal rule: %p: ", *num, offset, r);
+
+		r->index = *num;
+		r->offset = offset;
+		memcpy(r->entry, e, e->next_offset);
+		r->counter_map.maptype = COUNTER_MAP_NORMAL_MAP;
+		r->counter_map.mappos = r->index;
+
+		/* handling of jumps, etc. */
+		if (!strcmp(GET_TARGET(e)->u.user.name, STANDARD_TARGET)) {
+			STRUCT_STANDARD_TARGET *t;
+
+			t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
+			if (t->target.u.target_size
+			    != ALIGN(sizeof(STRUCT_STANDARD_TARGET))) {
+				errno = EINVAL;
+				return -1;
+			}
+
+			if (t->verdict < 0) {
+				DEBUGP_C("standard, verdict=%d\n", t->verdict);
+				r->type = IPTCC_R_STANDARD;
+			} else if (t->verdict == r->offset+e->next_offset) {
+				DEBUGP_C("fallthrough\n");
+				r->type = IPTCC_R_FALLTHROUGH;
+			} else {
+				DEBUGP_C("jump, target=%u\n", t->verdict);
+				r->type = IPTCC_R_JUMP;
+				/* Jump target fixup has to be deferred
+				 * until second pass, since we migh not
+				 * yet have parsed the target */
+			}
+		} else {
+			DEBUGP_C("module, target=%s\n", GET_TARGET(e)->u.user.name);
+			r->type = IPTCC_R_MODULE;
+		}
+
+		list_add_tail(&r->list, &h->chain_iterator_cur->rules);
+		h->chain_iterator_cur->num_rules++;
+	}
+out_inc:
+	(*num)++;
+	return 0;
+}
+
+
+/* parse an iptables blob into it's pieces */
+static int parse_table(struct xtc_handle *h)
+{
+	STRUCT_ENTRY *prev;
+	unsigned int num = 0;
+	struct chain_head *c;
+
+	/* Assume that chains offsets are sorted, this verified during
+	   parsing of ruleset (in __iptcc_p_add_chain())*/
+	h->sorted_offsets = 1;
+
+	/* First pass: over ruleset blob */
+	ENTRY_ITERATE(h->entries->entrytable, h->entries->size,
+			cache_add_entry, h, &prev, &num);
+
+	/* Build the chain index, used for chain list search speedup */
+	if ((iptcc_chain_index_alloc(h)) < 0)
+		return -ENOMEM;
+	iptcc_chain_index_build(h);
+
+	/* Second pass: fixup parsed data from first pass */
+	list_for_each_entry(c, &h->chains, list) {
+		struct rule_head *r;
+		list_for_each_entry(r, &c->rules, list) {
+			struct chain_head *lc;
+			STRUCT_STANDARD_TARGET *t;
+
+			if (r->type != IPTCC_R_JUMP)
+				continue;
+
+			t = (STRUCT_STANDARD_TARGET *)GET_TARGET(r->entry);
+			lc = iptcc_find_chain_by_offset(h, t->verdict);
+			if (!lc)
+				return -1;
+			r->jump = lc;
+			lc->references++;
+		}
+	}
+
+	return 1;
+}
+
+
+/**********************************************************************
+ * RULESET COMPILATION (cache -> blob)
+ **********************************************************************/
+
+/* Convenience structures */
+struct iptcb_chain_start{
+	STRUCT_ENTRY e;
+	struct ipt_error_target name;
+};
+#define IPTCB_CHAIN_START_SIZE	(sizeof(STRUCT_ENTRY) +			\
+				 ALIGN(sizeof(struct ipt_error_target)))
+
+struct iptcb_chain_foot {
+	STRUCT_ENTRY e;
+	STRUCT_STANDARD_TARGET target;
+};
+#define IPTCB_CHAIN_FOOT_SIZE	(sizeof(STRUCT_ENTRY) +			\
+				 ALIGN(sizeof(STRUCT_STANDARD_TARGET)))
+
+struct iptcb_chain_error {
+	STRUCT_ENTRY entry;
+	struct ipt_error_target target;
+};
+#define IPTCB_CHAIN_ERROR_SIZE	(sizeof(STRUCT_ENTRY) +			\
+				 ALIGN(sizeof(struct ipt_error_target)))
+
+
+
+/* compile rule from cache into blob */
+static inline int iptcc_compile_rule (struct xtc_handle *h, STRUCT_REPLACE *repl, struct rule_head *r)
+{
+	/* handle jumps */
+	if (r->type == IPTCC_R_JUMP) {
+		STRUCT_STANDARD_TARGET *t;
+		t = (STRUCT_STANDARD_TARGET *)GET_TARGET(r->entry);
+		/* memset for memcmp convenience on delete/replace */
+		memset(t->target.u.user.name, 0, FUNCTION_MAXNAMELEN);
+		strcpy(t->target.u.user.name, STANDARD_TARGET);
+		/* Jumps can only happen to builtin chains, so we
+		 * can safely assume that they always have a header */
+		t->verdict = r->jump->head_offset + IPTCB_CHAIN_START_SIZE;
+	} else if (r->type == IPTCC_R_FALLTHROUGH) {
+		STRUCT_STANDARD_TARGET *t;
+		t = (STRUCT_STANDARD_TARGET *)GET_TARGET(r->entry);
+		t->verdict = r->offset + r->size;
+	}
+
+	/* copy entry from cache to blob */
+	memcpy((char *)repl->entries+r->offset, r->entry, r->size);
+
+	return 1;
+}
+
+/* compile chain from cache into blob */
+static int iptcc_compile_chain(struct xtc_handle *h, STRUCT_REPLACE *repl, struct chain_head *c)
+{
+	int ret;
+	struct rule_head *r;
+	struct iptcb_chain_start *head;
+	struct iptcb_chain_foot *foot;
+
+	/* only user-defined chains have heaer */
+	if (!iptcc_is_builtin(c)) {
+		/* put chain header in place */
+		head = (void *)repl->entries + c->head_offset;
+		head->e.target_offset = sizeof(STRUCT_ENTRY);
+		head->e.next_offset = IPTCB_CHAIN_START_SIZE;
+		strcpy(head->name.t.u.user.name, ERROR_TARGET);
+		head->name.t.u.target_size =
+				ALIGN(sizeof(struct ipt_error_target));
+		strcpy(head->name.error, c->name);
+	} else {
+		repl->hook_entry[c->hooknum-1] = c->head_offset;
+		repl->underflow[c->hooknum-1] = c->foot_offset;
+	}
+
+	/* iterate over rules */
+	list_for_each_entry(r, &c->rules, list) {
+		ret = iptcc_compile_rule(h, repl, r);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* put chain footer in place */
+	foot = (void *)repl->entries + c->foot_offset;
+	foot->e.target_offset = sizeof(STRUCT_ENTRY);
+	foot->e.next_offset = IPTCB_CHAIN_FOOT_SIZE;
+	strcpy(foot->target.target.u.user.name, STANDARD_TARGET);
+	foot->target.target.u.target_size =
+				ALIGN(sizeof(STRUCT_STANDARD_TARGET));
+	/* builtin targets have verdict, others return */
+	if (iptcc_is_builtin(c))
+		foot->target.verdict = c->verdict;
+	else
+		foot->target.verdict = RETURN;
+	/* set policy-counters */
+	memcpy(&foot->e.counters, &c->counters, sizeof(STRUCT_COUNTERS));
+
+	return 0;
+}
+
+/* calculate offset and number for every rule in the cache */
+static int iptcc_compile_chain_offsets(struct xtc_handle *h, struct chain_head *c,
+				       unsigned int *offset, unsigned int *num)
+{
+	struct rule_head *r;
+
+	c->head_offset = *offset;
+	DEBUGP("%s: chain_head %u, offset=%u\n", c->name, *num, *offset);
+
+	if (!iptcc_is_builtin(c))  {
+		/* Chain has header */
+		*offset += sizeof(STRUCT_ENTRY)
+			     + ALIGN(sizeof(struct ipt_error_target));
+		(*num)++;
+	}
+
+	list_for_each_entry(r, &c->rules, list) {
+		DEBUGP("rule %u, offset=%u, index=%u\n", *num, *offset, *num);
+		r->offset = *offset;
+		r->index = *num;
+		*offset += r->size;
+		(*num)++;
+	}
+
+	DEBUGP("%s; chain_foot %u, offset=%u, index=%u\n", c->name, *num,
+		*offset, *num);
+	c->foot_offset = *offset;
+	c->foot_index = *num;
+	*offset += sizeof(STRUCT_ENTRY)
+		   + ALIGN(sizeof(STRUCT_STANDARD_TARGET));
+	(*num)++;
+
+	return 1;
+}
+
+/* put the pieces back together again */
+static int iptcc_compile_table_prep(struct xtc_handle *h, unsigned int *size)
+{
+	struct chain_head *c;
+	unsigned int offset = 0, num = 0;
+	int ret = 0;
+
+	/* First pass: calculate offset for every rule */
+	list_for_each_entry(c, &h->chains, list) {
+		ret = iptcc_compile_chain_offsets(h, c, &offset, &num);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* Append one error rule at end of chain */
+	num++;
+	offset += sizeof(STRUCT_ENTRY)
+		  + ALIGN(sizeof(struct ipt_error_target));
+
+	/* ruleset size is now in offset */
+	*size = offset;
+	return num;
+}
+
+static int iptcc_compile_table(struct xtc_handle *h, STRUCT_REPLACE *repl)
+{
+	struct chain_head *c;
+	struct iptcb_chain_error *error;
+
+	/* Second pass: copy from cache to offsets, fill in jumps */
+	list_for_each_entry(c, &h->chains, list) {
+		int ret = iptcc_compile_chain(h, repl, c);
+		if (ret < 0)
+			return ret;
+	}
+
+	/* Append error rule at end of chain */
+	error = (void *)repl->entries + repl->size - IPTCB_CHAIN_ERROR_SIZE;
+	error->entry.target_offset = sizeof(STRUCT_ENTRY);
+	error->entry.next_offset = IPTCB_CHAIN_ERROR_SIZE;
+	error->target.t.u.user.target_size =
+		ALIGN(sizeof(struct ipt_error_target));
+	strcpy((char *)&error->target.t.u.user.name, ERROR_TARGET);
+	strcpy((char *)&error->target.error, "ERROR");
+
+	return 1;
+}
+
+/**********************************************************************
+ * EXTERNAL API (operates on cache only)
+ **********************************************************************/
+
+/* Allocate handle of given size */
+static struct xtc_handle *
+alloc_handle(const char *tablename, unsigned int size, unsigned int num_rules)
+{
+	size_t len;
+	struct xtc_handle *h;
+
+	len = sizeof(STRUCT_TC_HANDLE) + size;
+
+	h = malloc(sizeof(STRUCT_TC_HANDLE));
+	if (!h) {
+		errno = ENOMEM;
+		return NULL;
+	}
+	memset(h, 0, sizeof(*h));
+	INIT_LIST_HEAD(&h->chains);
+	strcpy(h->info.name, tablename);
+
+	h->entries = malloc(sizeof(STRUCT_GET_ENTRIES) + size);
+	if (!h->entries)
+		goto out_free_handle;
+
+	strcpy(h->entries->name, tablename);
+	h->entries->size = size;
+
+	return h;
+
+out_free_handle:
+	free(h);
+
+	return NULL;
+}
+
+
+struct xtc_handle *
+TC_INIT(const char *tablename)
+{
+	struct xtc_handle *h;
+	STRUCT_GETINFO info;
+	unsigned int tmp;
+	socklen_t s;
+	int sockfd;
+
+	iptc_fn = TC_INIT;
+
+	if (strlen(tablename) >= TABLE_MAXNAMELEN) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	sockfd = socket(TC_AF, SOCK_RAW, IPPROTO_RAW);
+	if (sockfd < 0)
+		return NULL;
+
+retry:
+	s = sizeof(info);
+
+	strcpy(info.name, tablename);
+	if (getsockopt(sockfd, TC_IPPROTO, SO_GET_INFO, &info, &s) < 0) {
+		close(sockfd);
+		return NULL;
+	}
+
+	DEBUGP("valid_hooks=0x%08x, num_entries=%u, size=%u\n",
+		info.valid_hooks, info.num_entries, info.size);
+
+	if ((h = alloc_handle(info.name, info.size, info.num_entries))
+	    == NULL) {
+		close(sockfd);
+		return NULL;
+	}
+
+	/* Initialize current state */
+	h->sockfd = sockfd;
+	h->info = info;
+
+	h->entries->size = h->info.size;
+
+	tmp = sizeof(STRUCT_GET_ENTRIES) + h->info.size;
+
+	if (getsockopt(h->sockfd, TC_IPPROTO, SO_GET_ENTRIES, h->entries,
+		       &tmp) < 0)
+		goto error;
+
+#ifdef IPTC_DEBUG2
+	{
+		int fd = open("/tmp/libiptc-so_get_entries.blob",
+				O_CREAT|O_WRONLY);
+		if (fd >= 0) {
+			write(fd, h->entries, tmp);
+			close(fd);
+		}
+	}
+#endif
+
+	if (parse_table(h) < 0)
+		goto error;
+
+	CHECK(h);
+	return h;
+error:
+	TC_FREE(h);
+	/* A different process changed the ruleset size, retry */
+	if (errno == EAGAIN)
+		goto retry;
+	return NULL;
+}
+
+void
+TC_FREE(struct xtc_handle *h)
+{
+	struct chain_head *c, *tmp;
+
+	iptc_fn = TC_FREE;
+	close(h->sockfd);
+
+	list_for_each_entry_safe(c, tmp, &h->chains, list) {
+		struct rule_head *r, *rtmp;
+
+		list_for_each_entry_safe(r, rtmp, &c->rules, list) {
+			free(r);
+		}
+
+		free(c);
+	}
+
+	iptcc_chain_index_free(h);
+
+	free(h->entries);
+	free(h);
+}
+
+static inline int
+print_match(const STRUCT_ENTRY_MATCH *m)
+{
+	printf("Match name: `%s'\n", m->u.user.name);
+	return 0;
+}
+
+static int dump_entry(STRUCT_ENTRY *e, struct xtc_handle *const handle);
+
+void
+TC_DUMP_ENTRIES(struct xtc_handle *const handle)
+{
+	iptc_fn = TC_DUMP_ENTRIES;
+	CHECK(handle);
+
+	printf("libiptc v%s. %u bytes.\n",
+	       XTABLES_VERSION, handle->entries->size);
+	printf("Table `%s'\n", handle->info.name);
+	printf("Hooks: pre/in/fwd/out/post = %x/%x/%x/%x/%x\n",
+	       handle->info.hook_entry[HOOK_PRE_ROUTING],
+	       handle->info.hook_entry[HOOK_LOCAL_IN],
+	       handle->info.hook_entry[HOOK_FORWARD],
+	       handle->info.hook_entry[HOOK_LOCAL_OUT],
+	       handle->info.hook_entry[HOOK_POST_ROUTING]);
+	printf("Underflows: pre/in/fwd/out/post = %x/%x/%x/%x/%x\n",
+	       handle->info.underflow[HOOK_PRE_ROUTING],
+	       handle->info.underflow[HOOK_LOCAL_IN],
+	       handle->info.underflow[HOOK_FORWARD],
+	       handle->info.underflow[HOOK_LOCAL_OUT],
+	       handle->info.underflow[HOOK_POST_ROUTING]);
+
+	ENTRY_ITERATE(handle->entries->entrytable, handle->entries->size,
+		      dump_entry, handle);
+}
+
+/* Does this chain exist? */
+int TC_IS_CHAIN(const char *chain, struct xtc_handle *const handle)
+{
+	iptc_fn = TC_IS_CHAIN;
+	return iptcc_find_label(chain, handle) != NULL;
+}
+
+static void iptcc_chain_iterator_advance(struct xtc_handle *handle)
+{
+	struct chain_head *c = handle->chain_iterator_cur;
+
+	if (c->list.next == &handle->chains)
+		handle->chain_iterator_cur = NULL;
+	else
+		handle->chain_iterator_cur =
+			list_entry(c->list.next, struct chain_head, list);
+}
+
+/* Iterator functions to run through the chains. */
+const char *
+TC_FIRST_CHAIN(struct xtc_handle *handle)
+{
+	struct chain_head *c = list_entry(handle->chains.next,
+					  struct chain_head, list);
+
+	iptc_fn = TC_FIRST_CHAIN;
+
+
+	if (list_empty(&handle->chains)) {
+		DEBUGP(": no chains\n");
+		return NULL;
+	}
+
+	handle->chain_iterator_cur = c;
+	iptcc_chain_iterator_advance(handle);
+
+	DEBUGP(": returning `%s'\n", c->name);
+	return c->name;
+}
+
+/* Iterator functions to run through the chains.  Returns NULL at end. */
+const char *
+TC_NEXT_CHAIN(struct xtc_handle *handle)
+{
+	struct chain_head *c = handle->chain_iterator_cur;
+
+	iptc_fn = TC_NEXT_CHAIN;
+
+	if (!c) {
+		DEBUGP(": no more chains\n");
+		return NULL;
+	}
+
+	iptcc_chain_iterator_advance(handle);
+
+	DEBUGP(": returning `%s'\n", c->name);
+	return c->name;
+}
+
+/* Get first rule in the given chain: NULL for empty chain. */
+const STRUCT_ENTRY *
+TC_FIRST_RULE(const char *chain, struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+
+	iptc_fn = TC_FIRST_RULE;
+
+	DEBUGP("first rule(%s): ", chain);
+
+	c = iptcc_find_label(chain, handle);
+	if (!c) {
+		errno = ENOENT;
+		return NULL;
+	}
+
+	/* Empty chain: single return/policy rule */
+	if (list_empty(&c->rules)) {
+		DEBUGP_C("no rules, returning NULL\n");
+		return NULL;
+	}
+
+	r = list_entry(c->rules.next, struct rule_head, list);
+	handle->rule_iterator_cur = r;
+	DEBUGP_C("%p\n", r);
+
+	return r->entry;
+}
+
+/* Returns NULL when rules run out. */
+const STRUCT_ENTRY *
+TC_NEXT_RULE(const STRUCT_ENTRY *prev, struct xtc_handle *handle)
+{
+	struct rule_head *r;
+
+	iptc_fn = TC_NEXT_RULE;
+	DEBUGP("rule_iterator_cur=%p...", handle->rule_iterator_cur);
+
+	if (handle->rule_iterator_cur == NULL) {
+		DEBUGP_C("returning NULL\n");
+		return NULL;
+	}
+
+	r = list_entry(handle->rule_iterator_cur->list.next,
+			struct rule_head, list);
+
+	iptc_fn = TC_NEXT_RULE;
+
+	DEBUGP_C("next=%p, head=%p...", &r->list,
+		&handle->rule_iterator_cur->chain->rules);
+
+	if (&r->list == &handle->rule_iterator_cur->chain->rules) {
+		handle->rule_iterator_cur = NULL;
+		DEBUGP_C("finished, returning NULL\n");
+		return NULL;
+	}
+
+	handle->rule_iterator_cur = r;
+
+	/* NOTE: prev is without any influence ! */
+	DEBUGP_C("returning rule %p\n", r);
+	return r->entry;
+}
+
+/* How many rules in this chain? */
+static unsigned int
+TC_NUM_RULES(const char *chain, struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	iptc_fn = TC_NUM_RULES;
+	CHECK(handle);
+
+	c = iptcc_find_label(chain, handle);
+	if (!c) {
+		errno = ENOENT;
+		return (unsigned int)-1;
+	}
+
+	return c->num_rules;
+}
+
+static const STRUCT_ENTRY *
+TC_GET_RULE(const char *chain, unsigned int n, struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+
+	iptc_fn = TC_GET_RULE;
+
+	CHECK(handle);
+
+	c = iptcc_find_label(chain, handle);
+	if (!c) {
+		errno = ENOENT;
+		return NULL;
+	}
+
+	r = iptcc_get_rule_num(c, n);
+	if (!r)
+		return NULL;
+	return r->entry;
+}
+
+/* Returns a pointer to the target name of this position. */
+static const char *standard_target_map(int verdict)
+{
+	switch (verdict) {
+		case RETURN:
+			return LABEL_RETURN;
+			break;
+		case -NF_ACCEPT-1:
+			return LABEL_ACCEPT;
+			break;
+		case -NF_DROP-1:
+			return LABEL_DROP;
+			break;
+		case -NF_QUEUE-1:
+			return LABEL_QUEUE;
+			break;
+		default:
+			fprintf(stderr, "ERROR: %d not a valid target)\n",
+				verdict);
+			abort();
+			break;
+	}
+	/* not reached */
+	return NULL;
+}
+
+/* Returns a pointer to the target name of this position. */
+const char *TC_GET_TARGET(const STRUCT_ENTRY *ce,
+			  struct xtc_handle *handle)
+{
+	STRUCT_ENTRY *e = (STRUCT_ENTRY *)ce;
+	struct rule_head *r = container_of(e, struct rule_head, entry[0]);
+
+	iptc_fn = TC_GET_TARGET;
+
+	switch(r->type) {
+		int spos;
+		case IPTCC_R_FALLTHROUGH:
+			return "";
+			break;
+		case IPTCC_R_JUMP:
+			DEBUGP("r=%p, jump=%p, name=`%s'\n", r, r->jump, r->jump->name);
+			return r->jump->name;
+			break;
+		case IPTCC_R_STANDARD:
+			spos = *(int *)GET_TARGET(e)->data;
+			DEBUGP("r=%p, spos=%d'\n", r, spos);
+			return standard_target_map(spos);
+			break;
+		case IPTCC_R_MODULE:
+			return GET_TARGET(e)->u.user.name;
+			break;
+	}
+	return NULL;
+}
+/* Is this a built-in chain?  Actually returns hook + 1. */
+int
+TC_BUILTIN(const char *chain, struct xtc_handle *const handle)
+{
+	struct chain_head *c;
+
+	iptc_fn = TC_BUILTIN;
+
+	c = iptcc_find_label(chain, handle);
+	if (!c) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	return iptcc_is_builtin(c);
+}
+
+/* Get the policy of a given built-in chain */
+const char *
+TC_GET_POLICY(const char *chain,
+	      STRUCT_COUNTERS *counters,
+	      struct xtc_handle *handle)
+{
+	struct chain_head *c;
+
+	iptc_fn = TC_GET_POLICY;
+
+	DEBUGP("called for chain %s\n", chain);
+
+	c = iptcc_find_label(chain, handle);
+	if (!c) {
+		errno = ENOENT;
+		return NULL;
+	}
+
+	if (!iptcc_is_builtin(c))
+		return NULL;
+
+	*counters = c->counters;
+
+	return standard_target_map(c->verdict);
+}
+
+static int
+iptcc_standard_map(struct rule_head *r, int verdict)
+{
+	STRUCT_ENTRY *e = r->entry;
+	STRUCT_STANDARD_TARGET *t;
+
+	t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
+
+	if (t->target.u.target_size
+	    != ALIGN(sizeof(STRUCT_STANDARD_TARGET))) {
+		errno = EINVAL;
+		return 0;
+	}
+	/* memset for memcmp convenience on delete/replace */
+	memset(t->target.u.user.name, 0, FUNCTION_MAXNAMELEN);
+	strcpy(t->target.u.user.name, STANDARD_TARGET);
+	t->verdict = verdict;
+
+	r->type = IPTCC_R_STANDARD;
+
+	return 1;
+}
+
+static int
+iptcc_map_target(struct xtc_handle *const handle,
+	   struct rule_head *r)
+{
+	STRUCT_ENTRY *e = r->entry;
+	STRUCT_ENTRY_TARGET *t = GET_TARGET(e);
+
+	/* Maybe it's empty (=> fall through) */
+	if (strcmp(t->u.user.name, "") == 0) {
+		r->type = IPTCC_R_FALLTHROUGH;
+		return 1;
+	}
+	/* Maybe it's a standard target name... */
+	else if (strcmp(t->u.user.name, LABEL_ACCEPT) == 0)
+		return iptcc_standard_map(r, -NF_ACCEPT - 1);
+	else if (strcmp(t->u.user.name, LABEL_DROP) == 0)
+		return iptcc_standard_map(r, -NF_DROP - 1);
+	else if (strcmp(t->u.user.name, LABEL_QUEUE) == 0)
+		return iptcc_standard_map(r, -NF_QUEUE - 1);
+	else if (strcmp(t->u.user.name, LABEL_RETURN) == 0)
+		return iptcc_standard_map(r, RETURN);
+	else if (TC_BUILTIN(t->u.user.name, handle)) {
+		/* Can't jump to builtins. */
+		errno = EINVAL;
+		return 0;
+	} else {
+		/* Maybe it's an existing chain name. */
+		struct chain_head *c;
+		DEBUGP("trying to find chain `%s': ", t->u.user.name);
+
+		c = iptcc_find_label(t->u.user.name, handle);
+		if (c) {
+			DEBUGP_C("found!\n");
+			r->type = IPTCC_R_JUMP;
+			r->jump = c;
+			c->references++;
+			return 1;
+		}
+		DEBUGP_C("not found :(\n");
+	}
+
+	/* Must be a module?  If not, kernel will reject... */
+	/* memset to all 0 for your memcmp convenience: don't clear version */
+	memset(t->u.user.name + strlen(t->u.user.name),
+	       0,
+	       FUNCTION_MAXNAMELEN - 1 - strlen(t->u.user.name));
+	r->type = IPTCC_R_MODULE;
+	set_changed(handle);
+	return 1;
+}
+
+/* Insert the entry `fw' in chain `chain' into position `rulenum'. */
+int
+TC_INSERT_ENTRY(const IPT_CHAINLABEL chain,
+		const STRUCT_ENTRY *e,
+		unsigned int rulenum,
+		struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+	struct list_head *prev;
+
+	iptc_fn = TC_INSERT_ENTRY;
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	/* first rulenum index = 0
+	   first c->num_rules index = 1 */
+	if (rulenum > c->num_rules) {
+		errno = E2BIG;
+		return 0;
+	}
+
+	/* If we are inserting at the end just take advantage of the
+	   double linked list, insert will happen before the entry
+	   prev points to. */
+	if (rulenum == c->num_rules) {
+		prev = &c->rules;
+	} else if (rulenum + 1 <= c->num_rules/2) {
+		r = iptcc_get_rule_num(c, rulenum + 1);
+		prev = &r->list;
+	} else {
+		r = iptcc_get_rule_num_reverse(c, c->num_rules - rulenum);
+		prev = &r->list;
+	}
+
+	if (!(r = iptcc_alloc_rule(c, e->next_offset))) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	memcpy(r->entry, e, e->next_offset);
+	r->counter_map.maptype = COUNTER_MAP_SET;
+
+	if (!iptcc_map_target(handle, r)) {
+		free(r);
+		return 0;
+	}
+
+	list_add_tail(&r->list, prev);
+	c->num_rules++;
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Atomically replace rule `rulenum' in `chain' with `fw'. */
+int
+TC_REPLACE_ENTRY(const IPT_CHAINLABEL chain,
+		 const STRUCT_ENTRY *e,
+		 unsigned int rulenum,
+		 struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r, *old;
+
+	iptc_fn = TC_REPLACE_ENTRY;
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (rulenum >= c->num_rules) {
+		errno = E2BIG;
+		return 0;
+	}
+
+	/* Take advantage of the double linked list if possible. */
+	if (rulenum + 1 <= c->num_rules/2) {
+		old = iptcc_get_rule_num(c, rulenum + 1);
+	} else {
+		old = iptcc_get_rule_num_reverse(c, c->num_rules - rulenum);
+	}
+
+	if (!(r = iptcc_alloc_rule(c, e->next_offset))) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	memcpy(r->entry, e, e->next_offset);
+	r->counter_map.maptype = COUNTER_MAP_SET;
+
+	if (!iptcc_map_target(handle, r)) {
+		free(r);
+		return 0;
+	}
+
+	list_add(&r->list, &old->list);
+	iptcc_delete_rule(old);
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Append entry `fw' to chain `chain'.  Equivalent to insert with
+   rulenum = length of chain. */
+int
+TC_APPEND_ENTRY(const IPT_CHAINLABEL chain,
+		const STRUCT_ENTRY *e,
+		struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+
+	iptc_fn = TC_APPEND_ENTRY;
+	if (!(c = iptcc_find_label(chain, handle))) {
+		DEBUGP("unable to find chain `%s'\n", chain);
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (!(r = iptcc_alloc_rule(c, e->next_offset))) {
+		DEBUGP("unable to allocate rule for chain `%s'\n", chain);
+		errno = ENOMEM;
+		return 0;
+	}
+
+	memcpy(r->entry, e, e->next_offset);
+	r->counter_map.maptype = COUNTER_MAP_SET;
+
+	if (!iptcc_map_target(handle, r)) {
+		DEBUGP("unable to map target of rule for chain `%s'\n", chain);
+		free(r);
+		return 0;
+	}
+
+	list_add_tail(&r->list, &c->rules);
+	c->num_rules++;
+
+	set_changed(handle);
+
+	return 1;
+}
+
+static inline int
+match_different(const STRUCT_ENTRY_MATCH *a,
+		const unsigned char *a_elems,
+		const unsigned char *b_elems,
+		unsigned char **maskptr)
+{
+	const STRUCT_ENTRY_MATCH *b;
+	unsigned int i;
+
+	/* Offset of b is the same as a. */
+	b = (void *)b_elems + ((unsigned char *)a - a_elems);
+
+	if (a->u.match_size != b->u.match_size)
+		return 1;
+
+	if (strcmp(a->u.user.name, b->u.user.name) != 0)
+		return 1;
+
+	*maskptr += ALIGN(sizeof(*a));
+
+	for (i = 0; i < a->u.match_size - ALIGN(sizeof(*a)); i++)
+		if (((a->data[i] ^ b->data[i]) & (*maskptr)[i]) != 0)
+			return 1;
+	*maskptr += i;
+	return 0;
+}
+
+static inline int
+target_same(struct rule_head *a, struct rule_head *b,const unsigned char *mask)
+{
+	unsigned int i;
+	STRUCT_ENTRY_TARGET *ta, *tb;
+
+	if (a->type != b->type)
+		return 0;
+
+	ta = GET_TARGET(a->entry);
+	tb = GET_TARGET(b->entry);
+
+	switch (a->type) {
+	case IPTCC_R_FALLTHROUGH:
+		return 1;
+	case IPTCC_R_JUMP:
+		return a->jump == b->jump;
+	case IPTCC_R_STANDARD:
+		return ((STRUCT_STANDARD_TARGET *)ta)->verdict
+			== ((STRUCT_STANDARD_TARGET *)tb)->verdict;
+	case IPTCC_R_MODULE:
+		if (ta->u.target_size != tb->u.target_size)
+			return 0;
+		if (strcmp(ta->u.user.name, tb->u.user.name) != 0)
+			return 0;
+
+		for (i = 0; i < ta->u.target_size - sizeof(*ta); i++)
+			if (((ta->data[i] ^ tb->data[i]) & mask[i]) != 0)
+				return 0;
+		return 1;
+	default:
+		fprintf(stderr, "ERROR: bad type %i\n", a->type);
+		abort();
+	}
+}
+
+static unsigned char *
+is_same(const STRUCT_ENTRY *a,
+	const STRUCT_ENTRY *b,
+	unsigned char *matchmask);
+
+/* Delete the first rule in `chain' which matches `fw'. */
+int
+TC_DELETE_ENTRY(const IPT_CHAINLABEL chain,
+		const STRUCT_ENTRY *origfw,
+		unsigned char *matchmask,
+		struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r, *i;
+
+	iptc_fn = TC_DELETE_ENTRY;
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	/* Create a rule_head from origfw. */
+	r = iptcc_alloc_rule(c, origfw->next_offset);
+	if (!r) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	memcpy(r->entry, origfw, origfw->next_offset);
+	r->counter_map.maptype = COUNTER_MAP_NOMAP;
+	if (!iptcc_map_target(handle, r)) {
+		DEBUGP("unable to map target of rule for chain `%s'\n", chain);
+		free(r);
+		return 0;
+	} else {
+		/* iptcc_map_target increment target chain references
+		 * since this is a fake rule only used for matching
+		 * the chain references count is decremented again.
+		 */
+		if (r->type == IPTCC_R_JUMP
+		    && r->jump)
+			r->jump->references--;
+	}
+
+	list_for_each_entry(i, &c->rules, list) {
+		unsigned char *mask;
+
+		mask = is_same(r->entry, i->entry, matchmask);
+		if (!mask)
+			continue;
+
+		if (!target_same(r, i, mask))
+			continue;
+
+		/* If we are about to delete the rule that is the
+		 * current iterator, move rule iterator back.  next
+		 * pointer will then point to real next node */
+		if (i == handle->rule_iterator_cur) {
+			handle->rule_iterator_cur =
+				list_entry(handle->rule_iterator_cur->list.prev,
+					   struct rule_head, list);
+		}
+
+		c->num_rules--;
+		iptcc_delete_rule(i);
+
+		set_changed(handle);
+		free(r);
+		return 1;
+	}
+
+	free(r);
+	errno = ENOENT;
+	return 0;
+}
+
+
+/* Delete the rule in position `rulenum' in `chain'. */
+int
+TC_DELETE_NUM_ENTRY(const IPT_CHAINLABEL chain,
+		    unsigned int rulenum,
+		    struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+
+	iptc_fn = TC_DELETE_NUM_ENTRY;
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (rulenum >= c->num_rules) {
+		errno = E2BIG;
+		return 0;
+	}
+
+	/* Take advantage of the double linked list if possible. */
+	if (rulenum + 1 <= c->num_rules/2) {
+		r = iptcc_get_rule_num(c, rulenum + 1);
+	} else {
+		r = iptcc_get_rule_num_reverse(c, c->num_rules - rulenum);
+	}
+
+	/* If we are about to delete the rule that is the current
+	 * iterator, move rule iterator back.  next pointer will then
+	 * point to real next node */
+	if (r == handle->rule_iterator_cur) {
+		handle->rule_iterator_cur =
+			list_entry(handle->rule_iterator_cur->list.prev,
+				   struct rule_head, list);
+	}
+
+	c->num_rules--;
+	iptcc_delete_rule(r);
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Flushes the entries in the given chain (ie. empties chain). */
+int
+TC_FLUSH_ENTRIES(const IPT_CHAINLABEL chain, struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r, *tmp;
+
+	iptc_fn = TC_FLUSH_ENTRIES;
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	list_for_each_entry_safe(r, tmp, &c->rules, list) {
+		iptcc_delete_rule(r);
+	}
+
+	c->num_rules = 0;
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Zeroes the counters in a chain. */
+int
+TC_ZERO_ENTRIES(const IPT_CHAINLABEL chain, struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+
+	iptc_fn = TC_ZERO_ENTRIES;
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (c->counter_map.maptype == COUNTER_MAP_NORMAL_MAP)
+		c->counter_map.maptype = COUNTER_MAP_ZEROED;
+
+	list_for_each_entry(r, &c->rules, list) {
+		if (r->counter_map.maptype == COUNTER_MAP_NORMAL_MAP)
+			r->counter_map.maptype = COUNTER_MAP_ZEROED;
+	}
+
+	set_changed(handle);
+
+	return 1;
+}
+
+STRUCT_COUNTERS *
+TC_READ_COUNTER(const IPT_CHAINLABEL chain,
+		unsigned int rulenum,
+		struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+
+	iptc_fn = TC_READ_COUNTER;
+	CHECK(*handle);
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return NULL;
+	}
+
+	if (!(r = iptcc_get_rule_num(c, rulenum))) {
+		errno = E2BIG;
+		return NULL;
+	}
+
+	return &r->entry[0].counters;
+}
+
+int
+TC_ZERO_COUNTER(const IPT_CHAINLABEL chain,
+		unsigned int rulenum,
+		struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+
+	iptc_fn = TC_ZERO_COUNTER;
+	CHECK(handle);
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (!(r = iptcc_get_rule_num(c, rulenum))) {
+		errno = E2BIG;
+		return 0;
+	}
+
+	if (r->counter_map.maptype == COUNTER_MAP_NORMAL_MAP)
+		r->counter_map.maptype = COUNTER_MAP_ZEROED;
+
+	set_changed(handle);
+
+	return 1;
+}
+
+int
+TC_SET_COUNTER(const IPT_CHAINLABEL chain,
+	       unsigned int rulenum,
+	       STRUCT_COUNTERS *counters,
+	       struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	struct rule_head *r;
+	STRUCT_ENTRY *e;
+
+	iptc_fn = TC_SET_COUNTER;
+	CHECK(handle);
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (!(r = iptcc_get_rule_num(c, rulenum))) {
+		errno = E2BIG;
+		return 0;
+	}
+
+	e = r->entry;
+	r->counter_map.maptype = COUNTER_MAP_SET;
+
+	memcpy(&e->counters, counters, sizeof(STRUCT_COUNTERS));
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Creates a new chain. */
+/* To create a chain, create two rules: error node and unconditional
+ * return. */
+int
+TC_CREATE_CHAIN(const IPT_CHAINLABEL chain, struct xtc_handle *handle)
+{
+	static struct chain_head *c;
+	int capacity;
+	int exceeded;
+
+	iptc_fn = TC_CREATE_CHAIN;
+
+	/* find_label doesn't cover built-in targets: DROP, ACCEPT,
+           QUEUE, RETURN. */
+	if (iptcc_find_label(chain, handle)
+	    || strcmp(chain, LABEL_DROP) == 0
+	    || strcmp(chain, LABEL_ACCEPT) == 0
+	    || strcmp(chain, LABEL_QUEUE) == 0
+	    || strcmp(chain, LABEL_RETURN) == 0) {
+		DEBUGP("Chain `%s' already exists\n", chain);
+		errno = EEXIST;
+		return 0;
+	}
+
+	if (strlen(chain)+1 > sizeof(IPT_CHAINLABEL)) {
+		DEBUGP("Chain name `%s' too long\n", chain);
+		errno = EINVAL;
+		return 0;
+	}
+
+	c = iptcc_alloc_chain_head(chain, 0);
+	if (!c) {
+		DEBUGP("Cannot allocate memory for chain `%s'\n", chain);
+		errno = ENOMEM;
+		return 0;
+
+	}
+	handle->num_chains++; /* New user defined chain */
+
+	DEBUGP("Creating chain `%s'\n", chain);
+	iptc_insert_chain(handle, c); /* Insert sorted */
+
+	/* Inserting chains don't change the correctness of the chain
+	 * index (except if its smaller than index[0], but that
+	 * handled by iptc_insert_chain).  It only causes longer lists
+	 * in the buckets. Thus, only rebuild chain index when the
+	 * capacity is exceed with CHAIN_INDEX_INSERT_MAX chains.
+	 */
+	capacity = handle->chain_index_sz * CHAIN_INDEX_BUCKET_LEN;
+	exceeded = handle->num_chains - capacity;
+	if (exceeded > CHAIN_INDEX_INSERT_MAX) {
+		debug("Capacity(%d) exceeded(%d) rebuild (chains:%d)\n",
+		      capacity, exceeded, handle->num_chains);
+		iptcc_chain_index_rebuild(handle);
+	}
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Get the number of references to this chain. */
+int
+TC_GET_REFERENCES(unsigned int *ref, const IPT_CHAINLABEL chain,
+		  struct xtc_handle *handle)
+{
+	struct chain_head *c;
+
+	iptc_fn = TC_GET_REFERENCES;
+	if (!(c = iptcc_find_label(chain, handle))) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	*ref = c->references;
+
+	return 1;
+}
+
+/* Deletes a chain. */
+int
+TC_DELETE_CHAIN(const IPT_CHAINLABEL chain, struct xtc_handle *handle)
+{
+	unsigned int references;
+	struct chain_head *c;
+
+	iptc_fn = TC_DELETE_CHAIN;
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		DEBUGP("cannot find chain `%s'\n", chain);
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (TC_BUILTIN(chain, handle)) {
+		DEBUGP("cannot remove builtin chain `%s'\n", chain);
+		errno = EINVAL;
+		return 0;
+	}
+
+	if (!TC_GET_REFERENCES(&references, chain, handle)) {
+		DEBUGP("cannot get references on chain `%s'\n", chain);
+		return 0;
+	}
+
+	if (references > 0) {
+		DEBUGP("chain `%s' still has references\n", chain);
+		errno = EMLINK;
+		return 0;
+	}
+
+	if (c->num_rules) {
+		DEBUGP("chain `%s' is not empty\n", chain);
+		errno = ENOTEMPTY;
+		return 0;
+	}
+
+	/* If we are about to delete the chain that is the current
+	 * iterator, move chain iterator forward. */
+	if (c == handle->chain_iterator_cur)
+		iptcc_chain_iterator_advance(handle);
+
+	handle->num_chains--; /* One user defined chain deleted */
+
+	//list_del(&c->list); /* Done in iptcc_chain_index_delete_chain() */
+	iptcc_chain_index_delete_chain(c, handle);
+	free(c);
+
+	DEBUGP("chain `%s' deleted\n", chain);
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Renames a chain. */
+int TC_RENAME_CHAIN(const IPT_CHAINLABEL oldname,
+		    const IPT_CHAINLABEL newname,
+		    struct xtc_handle *handle)
+{
+	struct chain_head *c;
+	iptc_fn = TC_RENAME_CHAIN;
+
+	/* find_label doesn't cover built-in targets: DROP, ACCEPT,
+           QUEUE, RETURN. */
+	if (iptcc_find_label(newname, handle)
+	    || strcmp(newname, LABEL_DROP) == 0
+	    || strcmp(newname, LABEL_ACCEPT) == 0
+	    || strcmp(newname, LABEL_QUEUE) == 0
+	    || strcmp(newname, LABEL_RETURN) == 0) {
+		errno = EEXIST;
+		return 0;
+	}
+
+	if (!(c = iptcc_find_label(oldname, handle))
+	    || TC_BUILTIN(oldname, handle)) {
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (strlen(newname)+1 > sizeof(IPT_CHAINLABEL)) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	/* This only unlinks "c" from the list, thus no free(c) */
+	iptcc_chain_index_delete_chain(c, handle);
+
+	/* Change the name of the chain */
+	strncpy(c->name, newname, sizeof(IPT_CHAINLABEL));
+
+	/* Insert sorted into to list again */
+	iptc_insert_chain(handle, c);
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Sets the policy on a built-in chain. */
+int
+TC_SET_POLICY(const IPT_CHAINLABEL chain,
+	      const IPT_CHAINLABEL policy,
+	      STRUCT_COUNTERS *counters,
+	      struct xtc_handle *handle)
+{
+	struct chain_head *c;
+
+	iptc_fn = TC_SET_POLICY;
+
+	if (!(c = iptcc_find_label(chain, handle))) {
+		DEBUGP("cannot find chain `%s'\n", chain);
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (!iptcc_is_builtin(c)) {
+		DEBUGP("cannot set policy of userdefinedchain `%s'\n", chain);
+		errno = ENOENT;
+		return 0;
+	}
+
+	if (strcmp(policy, LABEL_ACCEPT) == 0)
+		c->verdict = -NF_ACCEPT - 1;
+	else if (strcmp(policy, LABEL_DROP) == 0)
+		c->verdict = -NF_DROP - 1;
+	else {
+		errno = EINVAL;
+		return 0;
+	}
+
+	if (counters) {
+		/* set byte and packet counters */
+		memcpy(&c->counters, counters, sizeof(STRUCT_COUNTERS));
+		c->counter_map.maptype = COUNTER_MAP_SET;
+	} else {
+		c->counter_map.maptype = COUNTER_MAP_NOMAP;
+	}
+
+	set_changed(handle);
+
+	return 1;
+}
+
+/* Without this, on gcc 2.7.2.3, we get:
+   libiptc.c: In function `TC_COMMIT':
+   libiptc.c:833: fixed or forbidden register was spilled.
+   This may be due to a compiler bug or to impossible asm
+   statements or clauses.
+*/
+static void
+subtract_counters(STRUCT_COUNTERS *answer,
+		  const STRUCT_COUNTERS *a,
+		  const STRUCT_COUNTERS *b)
+{
+	answer->pcnt = a->pcnt - b->pcnt;
+	answer->bcnt = a->bcnt - b->bcnt;
+}
+
+
+static void counters_nomap(STRUCT_COUNTERS_INFO *newcounters, unsigned int idx)
+{
+	newcounters->counters[idx] = ((STRUCT_COUNTERS) { 0, 0});
+	DEBUGP_C("NOMAP => zero\n");
+}
+
+static void counters_normal_map(STRUCT_COUNTERS_INFO *newcounters,
+				STRUCT_REPLACE *repl, unsigned int idx,
+				unsigned int mappos)
+{
+	/* Original read: X.
+	 * Atomic read on replacement: X + Y.
+	 * Currently in kernel: Z.
+	 * Want in kernel: X + Y + Z.
+	 * => Add in X + Y
+	 * => Add in replacement read.
+	 */
+	newcounters->counters[idx] = repl->counters[mappos];
+	DEBUGP_C("NORMAL_MAP => mappos %u \n", mappos);
+}
+
+static void counters_map_zeroed(STRUCT_COUNTERS_INFO *newcounters,
+				STRUCT_REPLACE *repl, unsigned int idx,
+				unsigned int mappos, STRUCT_COUNTERS *counters)
+{
+	/* Original read: X.
+	 * Atomic read on replacement: X + Y.
+	 * Currently in kernel: Z.
+	 * Want in kernel: Y + Z.
+	 * => Add in Y.
+	 * => Add in (replacement read - original read).
+	 */
+	subtract_counters(&newcounters->counters[idx],
+			  &repl->counters[mappos],
+			  counters);
+	DEBUGP_C("ZEROED => mappos %u\n", mappos);
+}
+
+static void counters_map_set(STRUCT_COUNTERS_INFO *newcounters,
+                             unsigned int idx, STRUCT_COUNTERS *counters)
+{
+	/* Want to set counter (iptables-restore) */
+
+	memcpy(&newcounters->counters[idx], counters,
+		sizeof(STRUCT_COUNTERS));
+
+	DEBUGP_C("SET\n");
+}
+
+
+int
+TC_COMMIT(struct xtc_handle *handle)
+{
+	/* Replace, then map back the counters. */
+	STRUCT_REPLACE *repl;
+	STRUCT_COUNTERS_INFO *newcounters;
+	struct chain_head *c;
+	int ret;
+	size_t counterlen;
+	int new_number;
+	unsigned int new_size;
+
+	iptc_fn = TC_COMMIT;
+	CHECK(*handle);
+
+	/* Don't commit if nothing changed. */
+	if (!handle->changed)
+		goto finished;
+
+	new_number = iptcc_compile_table_prep(handle, &new_size);
+	if (new_number < 0) {
+		errno = ENOMEM;
+		goto out_zero;
+	}
+
+	repl = malloc(sizeof(*repl) + new_size);
+	if (!repl) {
+		errno = ENOMEM;
+		goto out_zero;
+	}
+	memset(repl, 0, sizeof(*repl) + new_size);
+
+#if 0
+	TC_DUMP_ENTRIES(*handle);
+#endif
+
+	counterlen = sizeof(STRUCT_COUNTERS_INFO)
+			+ sizeof(STRUCT_COUNTERS) * new_number;
+
+	/* These are the old counters we will get from kernel */
+	repl->counters = malloc(sizeof(STRUCT_COUNTERS)
+				* handle->info.num_entries);
+	if (!repl->counters) {
+		errno = ENOMEM;
+		goto out_free_repl;
+	}
+	/* These are the counters we're going to put back, later. */
+	newcounters = malloc(counterlen);
+	if (!newcounters) {
+		errno = ENOMEM;
+		goto out_free_repl_counters;
+	}
+	memset(newcounters, 0, counterlen);
+
+	strcpy(repl->name, handle->info.name);
+	repl->num_entries = new_number;
+	repl->size = new_size;
+
+	repl->num_counters = handle->info.num_entries;
+	repl->valid_hooks  = handle->info.valid_hooks;
+
+	DEBUGP("num_entries=%u, size=%u, num_counters=%u\n",
+		repl->num_entries, repl->size, repl->num_counters);
+
+	ret = iptcc_compile_table(handle, repl);
+	if (ret < 0) {
+		errno = ret;
+		goto out_free_newcounters;
+	}
+
+
+#ifdef IPTC_DEBUG2
+	{
+		int fd = open("/tmp/libiptc-so_set_replace.blob",
+				O_CREAT|O_WRONLY);
+		if (fd >= 0) {
+			write(fd, repl, sizeof(*repl) + repl->size);
+			close(fd);
+		}
+	}
+#endif
+
+	ret = setsockopt(handle->sockfd, TC_IPPROTO, SO_SET_REPLACE, repl,
+			 sizeof(*repl) + repl->size);
+	if (ret < 0)
+		goto out_free_newcounters;
+
+	/* Put counters back. */
+	strcpy(newcounters->name, handle->info.name);
+	newcounters->num_counters = new_number;
+
+	list_for_each_entry(c, &handle->chains, list) {
+		struct rule_head *r;
+
+		/* Builtin chains have their own counters */
+		if (iptcc_is_builtin(c)) {
+			DEBUGP("counter for chain-index %u: ", c->foot_index);
+			switch(c->counter_map.maptype) {
+			case COUNTER_MAP_NOMAP:
+				counters_nomap(newcounters, c->foot_index);
+				break;
+			case COUNTER_MAP_NORMAL_MAP:
+				counters_normal_map(newcounters, repl,
+						    c->foot_index,
+						    c->counter_map.mappos);
+				break;
+			case COUNTER_MAP_ZEROED:
+				counters_map_zeroed(newcounters, repl,
+						    c->foot_index,
+						    c->counter_map.mappos,
+						    &c->counters);
+				break;
+			case COUNTER_MAP_SET:
+				counters_map_set(newcounters, c->foot_index,
+						 &c->counters);
+				break;
+			}
+		}
+
+		list_for_each_entry(r, &c->rules, list) {
+			DEBUGP("counter for index %u: ", r->index);
+			switch (r->counter_map.maptype) {
+			case COUNTER_MAP_NOMAP:
+				counters_nomap(newcounters, r->index);
+				break;
+
+			case COUNTER_MAP_NORMAL_MAP:
+				counters_normal_map(newcounters, repl,
+						    r->index,
+						    r->counter_map.mappos);
+				break;
+
+			case COUNTER_MAP_ZEROED:
+				counters_map_zeroed(newcounters, repl,
+						    r->index,
+						    r->counter_map.mappos,
+						    &r->entry->counters);
+				break;
+
+			case COUNTER_MAP_SET:
+				counters_map_set(newcounters, r->index,
+						 &r->entry->counters);
+				break;
+			}
+		}
+	}
+
+#ifdef IPTC_DEBUG2
+	{
+		int fd = open("/tmp/libiptc-so_set_add_counters.blob",
+				O_CREAT|O_WRONLY);
+		if (fd >= 0) {
+			write(fd, newcounters, counterlen);
+			close(fd);
+		}
+	}
+#endif
+
+	ret = setsockopt(handle->sockfd, TC_IPPROTO, SO_SET_ADD_COUNTERS,
+			 newcounters, counterlen);
+	if (ret < 0)
+		goto out_free_newcounters;
+
+	free(repl->counters);
+	free(repl);
+	free(newcounters);
+
+finished:
+	return 1;
+
+out_free_newcounters:
+	free(newcounters);
+out_free_repl_counters:
+	free(repl->counters);
+out_free_repl:
+	free(repl);
+out_zero:
+	return 0;
+}
+
+/* Translates errno numbers into more human-readable form than strerror. */
+const char *
+TC_STRERROR(int err)
+{
+	unsigned int i;
+	struct table_struct {
+		void *fn;
+		int err;
+		const char *message;
+	} table [] =
+	  { { TC_INIT, EPERM, "Permission denied (you must be root)" },
+	    { TC_INIT, EINVAL, "Module is wrong version" },
+	    { TC_INIT, ENOENT,
+		    "Table does not exist (do you need to insmod?)" },
+	    { TC_DELETE_CHAIN, ENOTEMPTY, "Chain is not empty" },
+	    { TC_DELETE_CHAIN, EINVAL, "Can't delete built-in chain" },
+	    { TC_DELETE_CHAIN, EMLINK,
+	      "Can't delete chain with references left" },
+	    { TC_CREATE_CHAIN, EEXIST, "Chain already exists" },
+	    { TC_INSERT_ENTRY, E2BIG, "Index of insertion too big" },
+	    { TC_REPLACE_ENTRY, E2BIG, "Index of replacement too big" },
+	    { TC_DELETE_NUM_ENTRY, E2BIG, "Index of deletion too big" },
+	    { TC_READ_COUNTER, E2BIG, "Index of counter too big" },
+	    { TC_ZERO_COUNTER, E2BIG, "Index of counter too big" },
+	    { TC_INSERT_ENTRY, ELOOP, "Loop found in table" },
+	    { TC_INSERT_ENTRY, EINVAL, "Target problem" },
+	    /* ENOENT for DELETE probably means no matching rule */
+	    { TC_DELETE_ENTRY, ENOENT,
+	      "Bad rule (does a matching rule exist in that chain?)" },
+	    { TC_SET_POLICY, ENOENT,
+	      "Bad built-in chain name" },
+	    { TC_SET_POLICY, EINVAL,
+	      "Bad policy name" },
+
+	    { NULL, 0, "Incompatible with this kernel" },
+	    { NULL, ENOPROTOOPT, "iptables who? (do you need to insmod?)" },
+	    { NULL, ENOSYS, "Will be implemented real soon.  I promise ;)" },
+	    { NULL, ENOMEM, "Memory allocation problem" },
+	    { NULL, ENOENT, "No chain/target/match by that name" },
+	  };
+
+	for (i = 0; i < sizeof(table)/sizeof(struct table_struct); i++) {
+		if ((!table[i].fn || table[i].fn == iptc_fn)
+		    && table[i].err == err)
+			return table[i].message;
+	}
+
+	return strerror(err);
+}