text: /* Library which manipulates firewall rules.  Version 0.1. */
  
  /* 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). */
  
  #include <assert.h>
  #include <string.h>
  #include <errno.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <unistd.h>
  
  #ifdef DEBUG_CONNTRACK
  #define inline
  #endif
  
  #if !defined(__GLIBC__) || (__GLIBC__ < 2)
  typedef unsigned int socklen_t;
  #endif
  
  #include "libiptc/libiptc.h"
  
  #define IP_VERSION	4
  #define IP_OFFSET	0x1FFF
  
  #define HOOK_PRE_ROUTING	NF_IP_PRE_ROUTING
  #define HOOK_LOCAL_IN		NF_IP_LOCAL_IN
  #define HOOK_FORWARD		NF_IP_FORWARD
  #define HOOK_LOCAL_OUT		NF_IP_LOCAL_OUT
  #define HOOK_POST_ROUTING	NF_IP_POST_ROUTING
  
  #define STRUCT_ENTRY_TARGET	struct xt_entry_target
  #define STRUCT_ENTRY		struct ipt_entry
  #define STRUCT_ENTRY_MATCH	struct xt_entry_match
  #define STRUCT_GETINFO		struct ipt_getinfo
  #define STRUCT_GET_ENTRIES	struct ipt_get_entries
  #define STRUCT_COUNTERS		struct xt_counters
  #define STRUCT_COUNTERS_INFO	struct xt_counters_info
  #define STRUCT_STANDARD_TARGET	struct xt_standard_target
  #define STRUCT_REPLACE		struct ipt_replace
  
  #define ENTRY_ITERATE		IPT_ENTRY_ITERATE
  #define TABLE_MAXNAMELEN	XT_TABLE_MAXNAMELEN
  #define FUNCTION_MAXNAMELEN	XT_FUNCTION_MAXNAMELEN
  
  #define GET_TARGET		ipt_get_target
  
  #define ERROR_TARGET		XT_ERROR_TARGET
  #define NUMHOOKS		NF_IP_NUMHOOKS
  
  #define IPT_CHAINLABEL		xt_chainlabel
  
  #define TC_DUMP_ENTRIES		dump_entries
  #define TC_IS_CHAIN		iptc_is_chain
  #define TC_FIRST_CHAIN		iptc_first_chain
  #define TC_NEXT_CHAIN		iptc_next_chain
  #define TC_FIRST_RULE		iptc_first_rule
  #define TC_NEXT_RULE		iptc_next_rule
  #define TC_GET_TARGET		iptc_get_target
  #define TC_BUILTIN		iptc_builtin
  #define TC_GET_POLICY		iptc_get_policy
  #define TC_INSERT_ENTRY		iptc_insert_entry
  #define TC_REPLACE_ENTRY	iptc_replace_entry
  #define TC_APPEND_ENTRY		iptc_append_entry
  #define TC_CHECK_ENTRY		iptc_check_entry
  #define TC_DELETE_ENTRY		iptc_delete_entry
  #define TC_DELETE_NUM_ENTRY	iptc_delete_num_entry
  #define TC_FLUSH_ENTRIES	iptc_flush_entries
  #define TC_ZERO_ENTRIES		iptc_zero_entries
  #define TC_READ_COUNTER		iptc_read_counter
  #define TC_ZERO_COUNTER		iptc_zero_counter
  #define TC_SET_COUNTER		iptc_set_counter
  #define TC_CREATE_CHAIN		iptc_create_chain
  #define TC_GET_REFERENCES	iptc_get_references
  #define TC_DELETE_CHAIN		iptc_delete_chain
  #define TC_RENAME_CHAIN		iptc_rename_chain
  #define TC_SET_POLICY		iptc_set_policy
  #define TC_GET_RAW_SOCKET	iptc_get_raw_socket
  #define TC_INIT			iptc_init
  #define TC_FREE			iptc_free
  #define TC_COMMIT		iptc_commit
  #define TC_STRERROR		iptc_strerror
  #define TC_NUM_RULES		iptc_num_rules
  #define TC_GET_RULE		iptc_get_rule
  #define TC_OPS			iptc_ops
  
  #define TC_AF			AF_INET
  #define TC_IPPROTO		IPPROTO_IP
  
  #define SO_SET_REPLACE		IPT_SO_SET_REPLACE
  #define SO_SET_ADD_COUNTERS	IPT_SO_SET_ADD_COUNTERS
  #define SO_GET_INFO		IPT_SO_GET_INFO
  #define SO_GET_ENTRIES		IPT_SO_GET_ENTRIES
  #define SO_GET_VERSION		IPT_SO_GET_VERSION
  
  #define STANDARD_TARGET		XT_STANDARD_TARGET
  #define LABEL_RETURN		IPTC_LABEL_RETURN
  #define LABEL_ACCEPT		IPTC_LABEL_ACCEPT
  #define LABEL_DROP		IPTC_LABEL_DROP
  #define LABEL_QUEUE		IPTC_LABEL_QUEUE
  
  #define ALIGN			XT_ALIGN
  #define RETURN			XT_RETURN
  
  #include "libiptc.c"
  
  #define IP_PARTS_NATIVE(n)			\
  (unsigned int)((n)>>24)&0xFF,			\
  (unsigned int)((n)>>16)&0xFF,			\
  (unsigned int)((n)>>8)&0xFF,			\
  (unsigned int)((n)&0xFF)
  
  #define IP_PARTS(n) IP_PARTS_NATIVE(ntohl(n))
  
  static int
  dump_entry(struct ipt_entry *e, struct xtc_handle *const handle)
  {
  	size_t i;
  	STRUCT_ENTRY_TARGET *t;
  
  	printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
  	       iptcb_entry2offset(handle, e));
  	printf("SRC IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
  	       IP_PARTS(e->ip.src.s_addr),IP_PARTS(e->ip.smsk.s_addr));
  	printf("DST IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
  	       IP_PARTS(e->ip.dst.s_addr),IP_PARTS(e->ip.dmsk.s_addr));
  	printf("Interface: `%s'/", e->ip.iniface);
  	for (i = 0; i < IFNAMSIZ; i++)
  		printf("%c", e->ip.iniface_mask[i] ? 'X' : '.');
  	printf("to `%s'/", e->ip.outiface);
  	for (i = 0; i < IFNAMSIZ; i++)
  		printf("%c", e->ip.outiface_mask[i] ? 'X' : '.');
  	printf("\nProtocol: %u\n", e->ip.proto);
  	printf("Flags: %02X\n", e->ip.flags);
  	printf("Invflags: %02X\n", e->ip.invflags);
  	printf("Counters: %llu packets, %llu bytes\n",
  	       (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
  	printf("Cache: %08X\n", e->nfcache);
  
  	IPT_MATCH_ITERATE(e, print_match);
  
  	t = GET_TARGET(e);
  	printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
  	if (strcmp(t->u.user.name, STANDARD_TARGET) == 0) {
  		const unsigned char *data = t->data;
  		int pos = *(const int *)data;
  		if (pos < 0)
  			printf("verdict=%s\n",
  			       pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
  			       : pos == -NF_DROP-1 ? "NF_DROP"
  			       : pos == -NF_QUEUE-1 ? "NF_QUEUE"
  			       : pos == RETURN ? "RETURN"
  			       : "UNKNOWN");
  		else
  			printf("verdict=%u\n", pos);
  	} else if (strcmp(t->u.user.name, XT_ERROR_TARGET) == 0)
  		printf("error=`%s'\n", t->data);
  
  	printf("\n");
  	return 0;
  }
  
  static unsigned char *
  is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask)
  {
  	unsigned int i;
  	unsigned char *mptr;
  
  	/* Always compare head structures: ignore mask here. */
  	if (a->ip.src.s_addr != b->ip.src.s_addr
  	    || a->ip.dst.s_addr != b->ip.dst.s_addr
  	    || a->ip.smsk.s_addr != b->ip.smsk.s_addr
  	    || a->ip.dmsk.s_addr != b->ip.dmsk.s_addr
  	    || a->ip.proto != b->ip.proto
  	    || (a->ip.flags & ~IPT_F_NO_DEF_MATCH) != (b->ip.flags & ~IPT_F_NO_DEF_MATCH)
  	    || a->ip.invflags != b->ip.invflags)
  		return NULL;
  
  	for (i = 0; i < IFNAMSIZ; i++) {
  		if (a->ip.iniface_mask[i] != b->ip.iniface_mask[i])
  			return NULL;
  		if ((a->ip.iniface[i] & a->ip.iniface_mask[i])
  		    != (b->ip.iniface[i] & b->ip.iniface_mask[i]))
  			return NULL;
  		if (a->ip.outiface_mask[i] != b->ip.outiface_mask[i])
  			return NULL;
  		if ((a->ip.outiface[i] & a->ip.outiface_mask[i])
  		    != (b->ip.outiface[i] & b->ip.outiface_mask[i]))
  			return NULL;
  	}
  
  	if (a->target_offset != b->target_offset
  	    || a->next_offset != b->next_offset)
  		return NULL;
  
  	mptr = matchmask + sizeof(STRUCT_ENTRY);
  	if (IPT_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
  		return NULL;
  	mptr += XT_ALIGN(sizeof(struct xt_entry_target));
  
  	return mptr;
  }
  
  #if 0
  /***************************** DEBUGGING ********************************/
  static inline int
  unconditional(const struct ipt_ip *ip)
  {
  	unsigned int i;
  
  	for (i = 0; i < sizeof(*ip)/sizeof(uint32_t); i++)
  		if (((uint32_t *)ip)[i])
  			return 0;
  
  	return 1;
  }
  
  static inline int
  check_match(const STRUCT_ENTRY_MATCH *m, unsigned int *off)
  {
  	assert(m->u.match_size >= sizeof(STRUCT_ENTRY_MATCH));
  	assert(ALIGN(m->u.match_size) == m->u.match_size);
  
  	(*off) += m->u.match_size;
  	return 0;
  }
  
  static inline int
  check_entry(const STRUCT_ENTRY *e, unsigned int *i, unsigned int *off,
  	    unsigned int user_offset, int *was_return,
  	    struct xtc_handle *h)
  {
  	unsigned int toff;
  	STRUCT_STANDARD_TARGET *t;
  
  	assert(e->target_offset >= sizeof(STRUCT_ENTRY));
  	assert(e->next_offset >= e->target_offset
  	       + sizeof(STRUCT_ENTRY_TARGET));
  	toff = sizeof(STRUCT_ENTRY);
  	IPT_MATCH_ITERATE(e, check_match, &toff);
  
  	assert(toff == e->target_offset);
  
  	t = (STRUCT_STANDARD_TARGET *)
  		GET_TARGET((STRUCT_ENTRY *)e);
  	/* next_offset will have to be multiple of entry alignment. */
  	assert(e->next_offset == ALIGN(e->next_offset));
  	assert(e->target_offset == ALIGN(e->target_offset));
  	assert(t->target.u.target_size == ALIGN(t->target.u.target_size));
  	assert(!TC_IS_CHAIN(t->target.u.user.name, h));
  
  	if (strcmp(t->target.u.user.name, STANDARD_TARGET) == 0) {
  		assert(t->target.u.target_size
  		       == ALIGN(sizeof(STRUCT_STANDARD_TARGET)));
  
  		assert(t->verdict == -NF_DROP-1
  		       || t->verdict == -NF_ACCEPT-1
  		       || t->verdict == RETURN
  		       || t->verdict < (int)h->entries->size);
  
  		if (t->verdict >= 0) {
  			STRUCT_ENTRY *te = get_entry(h, t->verdict);
  			int idx;
  
  			idx = iptcb_entry2index(h, te);
  			assert(strcmp(GET_TARGET(te)->u.user.name,
  				      XT_ERROR_TARGET)
  			       != 0);
  			assert(te != e);
  
  			/* Prior node must be error node, or this node. */
  			assert(t->verdict == iptcb_entry2offset(h, e)+e->next_offset
  			       || strcmp(GET_TARGET(index2entry(h, idx-1))
  					 ->u.user.name, XT_ERROR_TARGET)
  			       == 0);
  		}
  
  		if (t->verdict == RETURN
  		    && unconditional(&e->ip)
  		    && e->target_offset == sizeof(*e))
  			*was_return = 1;
  		else
  			*was_return = 0;
  	} else if (strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0) {
  		assert(t->target.u.target_size
  		       == ALIGN(sizeof(struct ipt_error_target)));
  
  		/* If this is in user area, previous must have been return */
  		if (*off > user_offset)
  			assert(*was_return);
  
  		*was_return = 0;
  	}
  	else *was_return = 0;
  
  	if (*off == user_offset)
  		assert(strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0);
  
  	(*off) += e->next_offset;
  	(*i)++;
  	return 0;
  }
  
  #ifdef IPTC_DEBUG
  /* Do every conceivable sanity check on the handle */
  static void
  do_check(struct xtc_handle *h, unsigned int line)
  {
  	unsigned int i, n;
  	unsigned int user_offset; /* Offset of first user chain */
  	int was_return;
  
  	assert(h->changed == 0 || h->changed == 1);
  	if (strcmp(h->info.name, "filter") == 0) {
  		assert(h->info.valid_hooks
  		       == (1 << NF_IP_LOCAL_IN
  			   | 1 << NF_IP_FORWARD
  			   | 1 << NF_IP_LOCAL_OUT));
  
  		/* Hooks should be first three */
  		assert(h->info.hook_entry[NF_IP_LOCAL_IN] == 0);
  
  		n = get_chain_end(h, 0);
  		n += get_entry(h, n)->next_offset;
  		assert(h->info.hook_entry[NF_IP_FORWARD] == n);
  
  		n = get_chain_end(h, n);
  		n += get_entry(h, n)->next_offset;
  		assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
  
  		user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
  	} else if (strcmp(h->info.name, "nat") == 0) {
  		assert((h->info.valid_hooks
  		        == (1 << NF_IP_PRE_ROUTING
  			    | 1 << NF_IP_POST_ROUTING
  			    | 1 << NF_IP_LOCAL_OUT)) ||
  		       (h->info.valid_hooks
  			== (1 << NF_IP_PRE_ROUTING
  			    | 1 << NF_IP_LOCAL_IN
  			    | 1 << NF_IP_POST_ROUTING
  			    | 1 << NF_IP_LOCAL_OUT)));
  
  		assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
  
  		n = get_chain_end(h, 0);
  
  		n += get_entry(h, n)->next_offset;
  		assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
  		n = get_chain_end(h, n);
  
  		n += get_entry(h, n)->next_offset;
  		assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
  		user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
  
  		if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
  			n = get_chain_end(h, n);
  			n += get_entry(h, n)->next_offset;
  			assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
  			user_offset = h->info.hook_entry[NF_IP_LOCAL_IN];
  		}
  
  	} else if (strcmp(h->info.name, "mangle") == 0) {
  		/* This code is getting ugly because linux < 2.4.18-pre6 had
  		 * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
  		 * */
  		assert((h->info.valid_hooks
  			== (1 << NF_IP_PRE_ROUTING
  			    | 1 << NF_IP_LOCAL_OUT)) || 
  		       (h->info.valid_hooks
  			== (1 << NF_IP_PRE_ROUTING
  			    | 1 << NF_IP_LOCAL_IN
  			    | 1 << NF_IP_FORWARD
  			    | 1 << NF_IP_LOCAL_OUT
  			    | 1 << NF_IP_POST_ROUTING)));
  
  		/* Hooks should be first five */
  		assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
  
  		n = get_chain_end(h, 0);
  
  		if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
  			n += get_entry(h, n)->next_offset;
  			assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
  			n = get_chain_end(h, n);
  		}
  
  		if (h->info.valid_hooks & (1 << NF_IP_FORWARD)) {
  			n += get_entry(h, n)->next_offset;
  			assert(h->info.hook_entry[NF_IP_FORWARD] == n);
  			n = get_chain_end(h, n);
  		}
  
  		n += get_entry(h, n)->next_offset;
  		assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
  		user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
  
  		if (h->info.valid_hooks & (1 << NF_IP_POST_ROUTING)) {
  			n = get_chain_end(h, n);
  			n += get_entry(h, n)->next_offset;
  			assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
  			user_offset = h->info.hook_entry[NF_IP_POST_ROUTING];
  		}
  	} else if (strcmp(h->info.name, "raw") == 0) {
  		assert(h->info.valid_hooks
  		       == (1 << NF_IP_PRE_ROUTING
  			   | 1 << NF_IP_LOCAL_OUT));
  
  		/* Hooks should be first three */
  		assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
  
  		n = get_chain_end(h, n);
  		n += get_entry(h, n)->next_offset;
  		assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
  
  		user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
  	} else {
  		fprintf(stderr, "Unknown table `%s'\n", h->info.name);
  		abort();
  	}
  
  	/* User chain == end of last builtin + policy entry */
  	user_offset = get_chain_end(h, user_offset);
  	user_offset += get_entry(h, user_offset)->next_offset;
  
  	/* Overflows should be end of entry chains, and unconditional
             policy nodes. */
  	for (i = 0; i < NUMHOOKS; i++) {
  		STRUCT_ENTRY *e;
  		STRUCT_STANDARD_TARGET *t;
  
  		if (!(h->info.valid_hooks & (1 << i)))
  			continue;
  		assert(h->info.underflow[i]
  		       == get_chain_end(h, h->info.hook_entry[i]));
  
  		e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
  		assert(unconditional(&e->ip));
  		assert(e->target_offset == sizeof(*e));
  		t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
  		assert(t->target.u.target_size == ALIGN(sizeof(*t)));
  		assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
  
  		assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
  		assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
  
  		/* Hooks and underflows must be valid entries */
  		entry2index(h, get_entry(h, h->info.hook_entry[i]));
  		entry2index(h, get_entry(h, h->info.underflow[i]));
  	}
  
  	assert(h->info.size
  	       >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
  					 +sizeof(STRUCT_STANDARD_TARGET)));
  
  	assert(h->entries.size
  	       >= (h->new_number
  		   * (sizeof(STRUCT_ENTRY)
  		      + sizeof(STRUCT_STANDARD_TARGET))));
  	assert(strcmp(h->info.name, h->entries.name) == 0);
  
  	i = 0; n = 0;
  	was_return = 0;
  	/* Check all the entries. */
  	ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
  		      check_entry, &i, &n, user_offset, &was_return, h);
  
  	assert(i == h->new_number);
  	assert(n == h->entries.size);
  
  	/* Final entry must be error node */
  	assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
  		      ->u.user.name,
  		      ERROR_TARGET) == 0);
  }
  #endif /*IPTC_DEBUG*/
  
  #endif
  