C++ CTINFO2DIR函数代码示例

static unsigned int
nf_nat_local_fn(unsigned int hooknum,
		struct sk_buff *skb,
		const struct net_device *in,
		const struct net_device *out,
		int (*okfn)(struct sk_buff *))
{
	const struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	unsigned int ret;

	/* root is playing with raw sockets. */
	if (skb->len < sizeof(struct iphdr) ||
	    ip_hdrlen(skb) < sizeof(struct iphdr))
		return NF_ACCEPT;

	ret = nf_nat_fn(hooknum, skb, in, out, okfn);
	if (ret != NF_DROP && ret != NF_STOLEN &&
	    (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);

		if (ct->tuplehash[dir].tuple.dst.u3.ip !=
		    ct->tuplehash[!dir].tuple.src.u3.ip) {
			if (ip_route_me_harder(skb, RTN_UNSPEC))
				ret = NF_DROP;
		}
#ifdef CONFIG_XFRM
		else if (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
			 ct->tuplehash[dir].tuple.dst.u.all !=
			 ct->tuplehash[!dir].tuple.src.u.all)
			if (ip_xfrm_me_harder(skb))
				ret = NF_DROP;
#endif
	}
	return ret;
}

static unsigned int
nf_nat_ipv6_local_fn(unsigned int hooknum,
		     struct sk_buff *skb,
		     const struct net_device *in,
		     const struct net_device *out,
		     int (*okfn)(struct sk_buff *))
{
	const struct nf_conn *ct;
	enum ip_conntrack_info ctinfo;
	unsigned int ret;

	/* root is playing with raw sockets. */
	if (skb->len < sizeof(struct ipv6hdr))
		return NF_ACCEPT;

	ret = nf_nat_ipv6_fn(hooknum, skb, in, out, okfn);
	if (ret != NF_DROP && ret != NF_STOLEN &&
	    (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);

		if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
				      &ct->tuplehash[!dir].tuple.src.u3)) {
			if (ip6_route_me_harder(skb))
				ret = NF_DROP;
		}
#ifdef CONFIG_XFRM
		else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
			 ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
			 ct->tuplehash[dir].tuple.dst.u.all !=
			 ct->tuplehash[!dir].tuple.src.u.all)
			if (nf_xfrm_me_harder(skb, AF_INET6))
				ret = NF_DROP;
#endif
	}
	return ret;
}

/* Returns verdict for packet, or -1 for invalid. */
static int tcp_packet(struct nf_conn *ct,
		      const struct sk_buff *skb,
		      unsigned int dataoff,
		      enum ip_conntrack_info ctinfo,
		      u_int8_t pf,
		      unsigned int hooknum)
{
	struct net *net = nf_ct_net(ct);
	struct nf_conntrack_tuple *tuple;
#if defined(CONFIG_MV_ETH_NFP_CT_LEARN)
	struct nf_conntrack_tuple *tupleInverseDir;
#endif
	enum tcp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	unsigned long timeout;
	unsigned int index;

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);

	spin_lock_bh(&ct->lock);
	old_state = ct->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(th);
	new_state = tcp_conntracks[dir][index][old_state];
	tuple = &ct->tuplehash[dir].tuple;
#if defined(CONFIG_MV_ETH_NFP_CT_LEARN)
	tupleInverseDir	= &ct->tuplehash[!dir].tuple;
#endif
	switch (new_state) {
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state < TCP_CONNTRACK_TIME_WAIT)
			break;
		/* RFC 1122: "When a connection is closed actively,
		 * it MUST linger in TIME-WAIT state for a time 2xMSL
		 * (Maximum Segment Lifetime). However, it MAY accept
		 * a new SYN from the remote TCP to reopen the connection
		 * directly from TIME-WAIT state, if..."
		 * We ignore the conditions because we are in the
		 * TIME-WAIT state anyway.
		 *
		 * Handle aborted connections: we and the server
		 * think there is an existing connection but the client
		 * aborts it and starts a new one.
		 */
		if (((ct->proto.tcp.seen[dir].flags
		      | ct->proto.tcp.seen[!dir].flags)
		     & IP_CT_TCP_FLAG_CLOSE_INIT)
		    || (ct->proto.tcp.last_dir == dir
		        && ct->proto.tcp.last_index == TCP_RST_SET)) {
			/* Attempt to reopen a closed/aborted connection.
			 * Delete this connection and look up again. */
			spin_unlock_bh(&ct->lock);

			/* Only repeat if we can actually remove the timer.
			 * Destruction may already be in progress in process
			 * context and we must give it a chance to terminate.
			 */
			if (nf_ct_kill(ct))
				return -NF_REPEAT;
			return NF_DROP;
		}
		/* Fall through */
	case TCP_CONNTRACK_IGNORE:
		/* Ignored packets:
		 *
		 * Our connection entry may be out of sync, so ignore
		 * packets which may signal the real connection between
		 * the client and the server.
		 *
		 * a) SYN in ORIGINAL
		 * b) SYN/ACK in REPLY
		 * c) ACK in reply direction after initial SYN in original.
		 *
		 * If the ignored packet is invalid, the receiver will send
		 * a RST we'll catch below.
		 */
		if (index == TCP_SYNACK_SET
		    && ct->proto.tcp.last_index == TCP_SYN_SET
		    && ct->proto.tcp.last_dir != dir
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			/* b) This SYN/ACK acknowledges a SYN that we earlier
			 * ignored as invalid. This means that the client and
			 * the server are both in sync, while the firewall is
			 * not. We kill this session and block the SYN/ACK so
			 * that the client cannot but retransmit its SYN and
			 * thus initiate a clean new session.
			 */
			spin_unlock_bh(&ct->lock);
			if (LOG_INVALID(net, IPPROTO_TCP))
				nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
					  "nf_ct_tcp: killing out of sync session ");
			nf_ct_kill(ct);
			return NF_DROP;
		}
		ct->proto.tcp.last_index = index;
		ct->proto.tcp.last_dir = dir;
//.........这里部分代码省略.........

static int quake3_help(struct sk_buff **pskb,
	struct ip_conntrack *ct,
	enum ip_conntrack_info ctinfo)
{
	struct udphdr _udph, *uh;
	struct ip_conntrack_expect *exp;
	void *data, *qb_ptr;
	int dir = CTINFO2DIR(ctinfo);
	int i, dataoff;
	int ret = NF_ACCEPT;

	
	/* Until there's been traffic both ways, don't look in packets. note:
	 * it's UDP ! */
	if (ctinfo != IP_CT_ESTABLISHED
	    && ctinfo != IP_CT_IS_REPLY) {
	        DEBUGP("ip_conntrack_quake3: not ok ! Conntrackinfo = %u\n",
			ctinfo);
	        return NF_ACCEPT;
	} else { 
		DEBUGP("ip_conntrack_quake3: it's ok ! Conntrackinfo = %u\n",
			ctinfo);
	}

	/* Valid UDP header? */
	uh = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
				sizeof(_udph), &_udph);
	if (!uh)
		return NF_ACCEPT;

	/* Any data? */
	dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);
	if (dataoff >= (*pskb)->len)
		return NF_ACCEPT;

	spin_lock_bh(&quake3_buffer_lock);
	qb_ptr = skb_header_pointer(*pskb, dataoff,
				    (*pskb)->len - dataoff, quake3_buffer);
	BUG_ON(qb_ptr == NULL);
	data = qb_ptr;

	
	if (strnicmp(data + 4, quake3s_conntrack.pattern, 
		     quake3s_conntrack.plen) == 0) {
		for(i=23;    /* 4 bytes filler, 18 bytes "getserversResponse", 
				1 byte "\" */
		    i+6 < ntohs(uh->len);
		    i+=7) {
			u_int32_t *ip = data+i;
			u_int16_t *port = data+i+4;
#if 0
			DEBUGP("ip_conntrack_quake3: adding server at offset "
			       "%u/%u %u.%u.%u.%u:%u\n", i, ntohs(uh->len),
			       NIPQUAD(*ip), ntohs(*port));
#endif

			exp = ip_conntrack_expect_alloc(ct);
			if (!exp) { 
				ret = NF_DROP;
				goto out;
			}

			memset(exp, 0, sizeof(*exp));

			exp->tuple.src.ip = ct->tuplehash[!dir].tuple.src.ip;
			exp->tuple.dst.ip = *ip;
			exp->tuple.dst.u.udp.port = *port;
			exp->tuple.dst.protonum = IPPROTO_UDP;

			exp->mask.src.ip = 0xffffffff;
			exp->mask.dst.ip = 0xffffffff;
			exp->mask.dst.u.udp.port = 0xffff;
			exp->mask.dst.protonum = 0xff;

			if (ip_nat_quake3_hook) 
				ret = ip_nat_quake3_hook(exp);
			else if (ip_conntrack_expect_related(exp) != 0) {
				ip_conntrack_expect_put(exp);
				ret = NF_DROP;
			}
			goto out;
		}
	}
	
out:
	spin_unlock_bh(&quake3_buffer_lock);

	return ret;
}

static unsigned int
ip_nat_fn(unsigned int hooknum,
	  struct sk_buff **pskb,
	  const struct net_device *in,
	  const struct net_device *out,
	  int (*okfn)(struct sk_buff *))
{
	struct ip_conntrack *ct;
	enum ip_conntrack_info ctinfo;
	struct ip_nat_info *info;
	/* maniptype == SRC for postrouting. */
	enum ip_nat_manip_type maniptype = HOOK2MANIP(hooknum);

	/* We never see fragments: conntrack defrags on pre-routing
	   and local-out, and ip_nat_out protects post-routing. */
	IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
		       & htons(IP_MF|IP_OFFSET)));

	(*pskb)->nfcache |= NFC_UNKNOWN;

	/* If we had a hardware checksum before, it's now invalid */
	if ((*pskb)->ip_summed == CHECKSUM_HW)
		(*pskb)->ip_summed = CHECKSUM_NONE;

	ct = ip_conntrack_get(*pskb, &ctinfo);
	/* Can't track?  It's not due to stress, or conntrack would
	   have dropped it.  Hence it's the user's responsibilty to
	   packet filter it out, or implement conntrack/NAT for that
	   protocol. 8) --RR */
	if (!ct) {
		/* Exception: ICMP redirect to new connection (not in
                   hash table yet).  We must not let this through, in
                   case we're doing NAT to the same network. */
		struct iphdr *iph = (*pskb)->nh.iph;
		struct icmphdr *hdr = (struct icmphdr *)
			((u_int32_t *)iph + iph->ihl);
		if (iph->protocol == IPPROTO_ICMP
		    && hdr->type == ICMP_REDIRECT)
			return NF_DROP;
		return NF_ACCEPT;
	}

	switch (ctinfo) {
	case IP_CT_RELATED:
	case IP_CT_RELATED+IP_CT_IS_REPLY:
		if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP) {
			return icmp_reply_translation(*pskb, ct, hooknum,
						      CTINFO2DIR(ctinfo));
		}
		/* Fall thru... (Only ICMPs can be IP_CT_IS_REPLY) */
	case IP_CT_NEW:
#ifdef CONFIG_IP_NF_NAT_LOCAL
		/* LOCAL_IN hook doesn't have a chain and thus doesn't care
		 * about new packets -HW */
		if (hooknum == NF_IP_LOCAL_IN)
			return NF_ACCEPT;
#endif
		info = &ct->nat.info;

		WRITE_LOCK(&ip_nat_lock);
		/* Seen it before?  This can happen for loopback, retrans,
		   or local packets.. */
		if (!(info->initialized & (1 << maniptype))) {
			int in_hashes = info->initialized;
			unsigned int ret;

			if (ct->master
			    && master_ct(ct)->nat.info.helper
			    && master_ct(ct)->nat.info.helper->expect) {
				ret = call_expect(master_ct(ct), pskb, 
						  hooknum, ct, info);
			} else {
				ret = ip_nat_rule_find(pskb, hooknum, in, out,
						       ct, info);
			}

			if (ret != NF_ACCEPT) {
				WRITE_UNLOCK(&ip_nat_lock);
				return ret;
			}

			if (in_hashes) {
				IP_NF_ASSERT(info->bysource.conntrack);
				replace_in_hashes(ct, info);
			} else {
				place_in_hashes(ct, info);
			}
		} else
			DEBUGP("Already setup manip %s for ct %p\n",
			       maniptype == IP_NAT_MANIP_SRC ? "SRC" : "DST",
			       ct);
		WRITE_UNLOCK(&ip_nat_lock);
		break;

	default:
		/* ESTABLISHED */
		IP_NF_ASSERT(ctinfo == IP_CT_ESTABLISHED
			     || ctinfo == (IP_CT_ESTABLISHED+IP_CT_IS_REPLY));
		info = &ct->nat.info;
	}
//.........这里部分代码省略.........

static int help(struct sk_buff *skb, unsigned int protoff,
		struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff;
	const struct iphdr *iph;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	const char *data_limit;
	char *data, *ib_ptr;
	int dir = CTINFO2DIR(ctinfo);
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_tuple *tuple;
	__be32 dcc_ip;
	u_int16_t dcc_port;
	__be16 port;
	int i, ret = NF_ACCEPT;
	char *addr_beg_p, *addr_end_p;
	typeof(nf_nat_irc_hook) nf_nat_irc;

	/* If packet is coming from IRC server */
	if (dir == IP_CT_DIR_REPLY)
		return NF_ACCEPT;

	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
		return NF_ACCEPT;

	/* Not a full tcp header? */
	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	/* No data? */
	dataoff = protoff + th->doff*4;
	if (dataoff >= skb->len)
		return NF_ACCEPT;

	spin_lock_bh(&irc_buffer_lock);
	ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
				    irc_buffer);
	BUG_ON(ib_ptr == NULL);

	data = ib_ptr;
	data_limit = ib_ptr + skb->len - dataoff;

	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
	 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
	while (data < data_limit - (19 + MINMATCHLEN)) {
		if (memcmp(data, "\1DCC ", 5)) {
			data++;
			continue;
		}
		data += 5;
		/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */

		iph = ip_hdr(skb);
		pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
			 &iph->saddr, ntohs(th->source),
			 &iph->daddr, ntohs(th->dest));

		for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
			if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
				/* no match */
				continue;
			}
			data += strlen(dccprotos[i]);
			pr_debug("DCC %s detected\n", dccprotos[i]);

			/* we have at least
			 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
			 * data left (== 14/13 bytes) */
			if (parse_dcc(data, data_limit, &dcc_ip,
				       &dcc_port, &addr_beg_p, &addr_end_p)) {
				pr_debug("unable to parse dcc command\n");
				continue;
			}

			pr_debug("DCC bound ip/port: %pI4:%u\n",
				 &dcc_ip, dcc_port);

			/* dcc_ip can be the internal OR external (NAT'ed) IP */
			tuple = &ct->tuplehash[dir].tuple;
			if (tuple->src.u3.ip != dcc_ip &&
			    tuple->dst.u3.ip != dcc_ip) {
				net_warn_ratelimited("Forged DCC command from %pI4: %pI4:%u\n",
						     &tuple->src.u3.ip,
						     &dcc_ip, dcc_port);
				continue;
			}

			exp = nf_ct_expect_alloc(ct);
			if (exp == NULL) {
				nf_ct_helper_log(skb, ct,
						 "cannot alloc expectation");
				ret = NF_DROP;
				goto out;
			}
			tuple = &ct->tuplehash[!dir].tuple;
			port = htons(dcc_port);
			nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
//.........这里部分代码省略.........

static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,
			       const char **dptr, unsigned int *datalen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	unsigned int coff, matchoff, matchlen;
	enum sip_header_types hdr;
	union nf_inet_addr addr;
	__be16 port;
	int request, in_header;

	/* Basic rules: requests and responses. */
	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
		if (ct_sip_parse_request(ct, *dptr, *datalen,
					 &matchoff, &matchlen,
					 &addr, &port) > 0 &&
		    !map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
			      &addr, port))
			return NF_DROP;
		request = 1;
	} else
		request = 0;

	if (nf_ct_protonum(ct) == IPPROTO_TCP)
		hdr = SIP_HDR_VIA_TCP;
	else
		hdr = SIP_HDR_VIA_UDP;

	/* Translate topmost Via header and parameters */
	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
				    hdr, NULL, &matchoff, &matchlen,
				    &addr, &port) > 0) {
		unsigned int matchend, poff, plen, buflen, n;
		char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];

		/* We're only interested in headers related to this
		 * connection */
		if (request) {
			if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip ||
			    port != ct->tuplehash[dir].tuple.src.u.udp.port)
				goto next;
		} else {
			if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip ||
			    port != ct->tuplehash[dir].tuple.dst.u.udp.port)
				goto next;
		}

		if (!map_addr(skb, dataoff, dptr, datalen, matchoff, matchlen,
			      &addr, port))
			return NF_DROP;

		matchend = matchoff + matchlen;

		/* The maddr= parameter (RFC 2361) specifies where to send
		 * the reply. */
		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
					       "maddr=", &poff, &plen,
					       &addr) > 0 &&
		    addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
		    addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) {
			buflen = sprintf(buffer, "%pI4",
					&ct->tuplehash[!dir].tuple.dst.u3.ip);
			if (!mangle_packet(skb, dataoff, dptr, datalen,
					   poff, plen, buffer, buflen))
				return NF_DROP;
		}

		/* The received= parameter (RFC 2361) contains the address
		 * from which the server received the request. */
		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
					       "received=", &poff, &plen,
					       &addr) > 0 &&
		    addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
		    addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) {
			buflen = sprintf(buffer, "%pI4",
					&ct->tuplehash[!dir].tuple.src.u3.ip);
			if (!mangle_packet(skb, dataoff, dptr, datalen,
					   poff, plen, buffer, buflen))
				return NF_DROP;
		}

		/* The rport= parameter (RFC 3581) contains the port number
		 * from which the server received the request. */
		if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen,
						 "rport=", &poff, &plen,
						 &n) > 0 &&
		    htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
		    htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
			__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
			buflen = sprintf(buffer, "%u", ntohs(p));
			if (!mangle_packet(skb, dataoff, dptr, datalen,
					   poff, plen, buffer, buflen))
				return NF_DROP;
		}
	}

next:
	/* Translate Contact headers */
	coff = 0;
//.........这里部分代码省略.........

static int help(struct sk_buff **pskb,
		struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff;
	struct tcphdr _tcph, *th;
	char *data, *data_limit, *ib_ptr;
	int dir = CTINFO2DIR(ctinfo);
	struct ip_conntrack_expect *exp;
	u32 seq;
	u_int32_t dcc_ip;
	u_int16_t dcc_port;
	int i, ret = NF_ACCEPT;
	char *addr_beg_p, *addr_end_p;

	DEBUGP("entered\n");

	/* If packet is coming from IRC server */
	if (dir == IP_CT_DIR_REPLY)
		return NF_ACCEPT;

	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED
	    && ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
		DEBUGP("Conntrackinfo = %u\n", ctinfo);
		return NF_ACCEPT;
	}

	/* Not a full tcp header? */
	th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
				sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	/* No data? */
	dataoff = (*pskb)->nh.iph->ihl*4 + th->doff*4;
	if (dataoff >= (*pskb)->len)
		return NF_ACCEPT;

	spin_lock_bh(&irc_buffer_lock);
	ib_ptr = skb_header_pointer(*pskb, dataoff,
				    (*pskb)->len - dataoff, irc_buffer);
	BUG_ON(ib_ptr == NULL);

	data = ib_ptr;
	data_limit = ib_ptr + (*pskb)->len - dataoff;

	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
	 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
	while (data < (data_limit - (19 + MINMATCHLEN))) {
		if (memcmp(data, "\1DCC ", 5)) {
			data++;
			continue;
		}

		data += 5;
		/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */

		DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n",
			NIPQUAD(iph->saddr), ntohs(th->source),
			NIPQUAD(iph->daddr), ntohs(th->dest));

		for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
			if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
				/* no match */
				continue;
			}

			DEBUGP("DCC %s detected\n", dccprotos[i]);
			data += strlen(dccprotos[i]);
			/* we have at least 
			 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
			 * data left (== 14/13 bytes) */
			if (parse_dcc((char *)data, data_limit, &dcc_ip,
				       &dcc_port, &addr_beg_p, &addr_end_p)) {
				/* unable to parse */
				DEBUGP("unable to parse dcc command\n");
				continue;
			}
			DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n",
				HIPQUAD(dcc_ip), dcc_port);

			/* dcc_ip can be the internal OR external (NAT'ed) IP
			 * Tiago Sousa <[email protected]> */
			if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip)
			    && ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip != htonl(dcc_ip)) {
				if (net_ratelimit())
					printk(KERN_WARNING
						"Forged DCC command from "
						"%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
				NIPQUAD(ct->tuplehash[dir].tuple.src.ip),
						HIPQUAD(dcc_ip), dcc_port);

				continue;
			}

			exp = ip_conntrack_expect_alloc(ct);
			if (exp == NULL) {
				ret = NF_DROP;
				goto out;
			}
//.........这里部分代码省略.........

static unsigned int ip_nat_sip(struct sk_buff **pskb,
			       enum ip_conntrack_info ctinfo,
			       struct ip_conntrack *ct,
			       const char **dptr)
{
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	unsigned int bufflen, dataoff;
	u_int32_t ip;
	u_int16_t port;

	dataoff = (*pskb)->nh.iph->ihl*4 + sizeof(struct udphdr);

	ip   = ct->tuplehash[!dir].tuple.dst.ip;
	port = ct->tuplehash[!dir].tuple.dst.u.udp.port;
	bufflen = sprintf(buffer, "%u.%u.%u.%u:%u", NIPQUAD(ip), ntohs(port));

	/* short packet ? */
	if (((*pskb)->len - dataoff) < (sizeof("SIP/2.0") - 1))
		return 0;

	/* Basic rules: requests and responses. */
	if (memcmp(*dptr, "SIP/2.0", sizeof("SIP/2.0") - 1) == 0) {
		const char *aux;

		if ((ctinfo) < IP_CT_IS_REPLY) {
			mangle_sip_packet(pskb, ctinfo, ct, dptr,
			                  (*pskb)->len - dataoff,
			                  buffer, bufflen,
			                  &ct_sip_hdrs[POS_CONTACT]);
			return 1;
		}

		if (!mangle_sip_packet(pskb, ctinfo, ct, dptr,
				       (*pskb)->len - dataoff,
		                       buffer, bufflen, &ct_sip_hdrs[POS_VIA]))
			return 0;

		/* This search should ignore case, but later.. */
		aux = ct_sip_search("CSeq:", *dptr, sizeof("CSeq:") - 1,
		                    (*pskb)->len - dataoff);
		if (!aux)
			return 0;

		if (!ct_sip_search("REGISTER", aux, sizeof("REGISTER"),
		    ct_sip_lnlen(aux, *dptr + (*pskb)->len - dataoff)))
			return 1;

		return mangle_sip_packet(pskb, ctinfo, ct, dptr,
					 (*pskb)->len - dataoff,
		                         buffer, bufflen,
					 &ct_sip_hdrs[POS_CONTACT]);
	}
	if ((ctinfo) < IP_CT_IS_REPLY) {
		if (!mangle_sip_packet(pskb, ctinfo, ct, dptr,
				       (*pskb)->len - dataoff,
		                       buffer, bufflen, &ct_sip_hdrs[POS_VIA]))
			return 0;

		/* Mangle Contact if exists only. - watch udp_nat_mangle()! */
		mangle_sip_packet(pskb, ctinfo, ct, dptr, (*pskb)->len - dataoff,
		                  buffer, bufflen, &ct_sip_hdrs[POS_CONTACT]);
		return 1;
	}
	/* This mangle requests headers. */
	return mangle_sip_packet(pskb, ctinfo, ct, dptr,
	                         ct_sip_lnlen(*dptr,
				              *dptr + (*pskb)->len - dataoff),
	                         buffer, bufflen, &ct_sip_hdrs[POS_REQ_HEADER]);
}

static unsigned int ip_nat_sdp_media(struct sk_buff *skb, unsigned int dataoff,
				     const char **dptr, unsigned int *datalen,
				     struct nf_conntrack_expect *rtp_exp,
				     struct nf_conntrack_expect *rtcp_exp,
				     unsigned int mediaoff,
				     unsigned int medialen,
				     union nf_inet_addr *rtp_addr)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	u_int16_t port;

	
	if (ct->tuplehash[dir].tuple.src.u3.ip ==
	    ct->tuplehash[!dir].tuple.dst.u3.ip)
		rtp_addr->ip = rtp_exp->tuple.dst.u3.ip;
	else
		rtp_addr->ip = ct->tuplehash[!dir].tuple.dst.u3.ip;

	rtp_exp->saved_ip = rtp_exp->tuple.dst.u3.ip;
	rtp_exp->tuple.dst.u3.ip = rtp_addr->ip;
	rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
	rtp_exp->dir = !dir;
	rtp_exp->expectfn = ip_nat_sip_expected;

	rtcp_exp->saved_ip = rtcp_exp->tuple.dst.u3.ip;
	rtcp_exp->tuple.dst.u3.ip = rtp_addr->ip;
	rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
	rtcp_exp->dir = !dir;
	rtcp_exp->expectfn = ip_nat_sip_expected;

	
	for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
	     port != 0; port += 2) {
		int ret;

		rtp_exp->tuple.dst.u.udp.port = htons(port);
		ret = nf_ct_expect_related(rtp_exp);
		if (ret == -EBUSY)
			continue;
		else if (ret < 0) {
			port = 0;
			break;
		}
		rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
		ret = nf_ct_expect_related(rtcp_exp);
		if (ret == 0)
			break;
		else if (ret == -EBUSY) {
			nf_ct_unexpect_related(rtp_exp);
			continue;
		} else if (ret < 0) {
			nf_ct_unexpect_related(rtp_exp);
			port = 0;
			break;
		}
	}

	if (port == 0)
		goto err1;

	
	if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
	    !ip_nat_sdp_port(skb, dataoff, dptr, datalen,
			     mediaoff, medialen, port))
		goto err2;

	return NF_ACCEPT;

err2:
	nf_ct_unexpect_related(rtp_exp);
	nf_ct_unexpect_related(rtcp_exp);
err1:
	return NF_DROP;
}

static unsigned int ip_nat_sip_expect(struct sk_buff *skb, unsigned int dataoff,
				      const char **dptr, unsigned int *datalen,
				      struct nf_conntrack_expect *exp,
				      unsigned int matchoff,
				      unsigned int matchlen)
{
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
	__be32 newip;
	u_int16_t port;
	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
	unsigned buflen;

	
	if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip)
		newip = exp->tuple.dst.u3.ip;
	else
		newip = ct->tuplehash[!dir].tuple.dst.u3.ip;

	if (exp->tuple.dst.u.udp.port ==
	    ct->tuplehash[dir].tuple.src.u.udp.port)
		port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
	else
		port = ntohs(exp->tuple.dst.u.udp.port);

	exp->saved_ip = exp->tuple.dst.u3.ip;
	exp->tuple.dst.u3.ip = newip;
	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
	exp->dir = !dir;
	exp->expectfn = ip_nat_sip_expected;

	for (; port != 0; port++) {
		int ret;

		exp->tuple.dst.u.udp.port = htons(port);
		ret = nf_ct_expect_related(exp);
		if (ret == 0)
			break;
		else if (ret != -EBUSY) {
			port = 0;
			break;
		}
	}

	if (port == 0)
		return NF_DROP;

	if (exp->tuple.dst.u3.ip != exp->saved_ip ||
	    exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
		buflen = sprintf(buffer, "%pI4:%u", &newip, port);
		if (!mangle_packet(skb, dataoff, dptr, datalen,
				   matchoff, matchlen, buffer, buflen))
			goto err;
	}
	return NF_ACCEPT;

err:
	nf_ct_unexpect_related(exp);
	return NF_DROP;
}

static unsigned int help(struct ip_conntrack *ct,
         		 struct ip_conntrack_expect *exp,
			 struct ip_nat_info *info,
			 enum ip_conntrack_info ctinfo,
			 unsigned int hooknum,
			 struct sk_buff **pskb)
{
	struct iphdr *iph = (*pskb)->nh.iph;
	struct tcphdr *tcph = (void *)iph + iph->ihl*4;
	unsigned int datalen;
	int dir;
	int score;
	struct ip_ct_sc_expect *exp_sc_info = &exp->help.exp_sc_info;

	/* Only mangle things once: original direction in POST_ROUTING
	   and reply direction on PRE_ROUTING. */
	dir = CTINFO2DIR(ctinfo);
	DEBUGP("nat_sc: help()\n");
	
#if 0
	if (!((hooknum == NF_IP_POST_ROUTING && dir == IP_CT_DIR_REPLY)
	      || (hooknum == NF_IP_PRE_ROUTING && dir == IP_CT_DIR_ORIGINAL))) {
#if 1
		DEBUGP("nat_sc: Not touching dir %s at hook %s\n",
		       dir == IP_CT_DIR_ORIGINAL ? "ORIG" : "REPLY",
		       hooknum == NF_IP_POST_ROUTING ? "POSTROUTING"
		       : hooknum == NF_IP_PRE_ROUTING ? "PREROUTING"
		       : hooknum == NF_IP_LOCAL_OUT ? "OUTPUT" : "???");
#endif
		return NF_ACCEPT;
	}
#endif

	datalen = (*pskb)->len - iph->ihl * 4 - tcph->doff * 4;
	score = 0;
	LOCK_BH(&ip_sc_lock);
	
	if (exp_sc_info->len) {
		/* If it's in the right range... */
		score += between(exp_sc_info->seq, ntohl(tcph->seq),
				 ntohl(tcph->seq) + datalen);
		score += between(exp_sc_info->seq + exp_sc_info->len,
				 ntohl(tcph->seq),
				 ntohl(tcph->seq) + datalen);
		if (score == 1) {
			/* Half a match?  This means a partial retransmisison.
			   It's a cracker being funky. */
			if (net_ratelimit()) {
				printk("SC_NAT: partial packet %u/%u in %u/%u\n",
				       exp_sc_info->seq, exp_sc_info->len,
				       ntohl(tcph->seq),
				       ntohl(tcph->seq) + datalen);
			}
			UNLOCK_BH(&ip_sc_lock);
			return NF_DROP;
		} else if (score == 2) {
			if (!sc_data_fixup(exp_sc_info, ct, datalen, pskb, ctinfo)) {
				UNLOCK_BH(&ip_sc_lock);
				return NF_DROP;
			}
			/* skb may have been reallocated */
			iph = (*pskb)->nh.iph;
			tcph = (void *)iph + iph->ihl*4;
		}
	}

	UNLOCK_BH(&ip_sc_lock);
	
	DEBUGP("nat_sc: ip_nat_seq_adjust()\n");
	ip_nat_seq_adjust(*pskb, ct, ctinfo);

	return NF_ACCEPT;
}

static int help(struct sk_buff *skb,
		unsigned int protoff,
		struct nf_conn *ct,
		enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff, datalen;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	void *sb_ptr;
	int ret = NF_ACCEPT;
	int dir = CTINFO2DIR(ctinfo);
	struct nf_ct_sane_master *ct_sane_info;
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_tuple *tuple;
	struct sane_request *req;
	struct sane_reply_net_start *reply;

	ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED &&
	    ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY)
		return NF_ACCEPT;

	/* Not a full tcp header? */
	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	/* No data? */
	dataoff = protoff + th->doff * 4;
	if (dataoff >= skb->len)
		return NF_ACCEPT;

	datalen = skb->len - dataoff;

	spin_lock_bh(&nf_sane_lock);
	sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer);
	BUG_ON(sb_ptr == NULL);

	if (dir == IP_CT_DIR_ORIGINAL) {
		if (datalen != sizeof(struct sane_request))
			goto out;

		req = sb_ptr;
		if (req->RPC_code != htonl(SANE_NET_START)) {
			/* Not an interesting command */
			ct_sane_info->state = SANE_STATE_NORMAL;
			goto out;
		}

		/* We're interested in the next reply */
		ct_sane_info->state = SANE_STATE_START_REQUESTED;
		goto out;
	}

	/* Is it a reply to an uninteresting command? */
	if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
		goto out;

	/* It's a reply to SANE_NET_START. */
	ct_sane_info->state = SANE_STATE_NORMAL;

	if (datalen < sizeof(struct sane_reply_net_start)) {
		pr_debug("nf_ct_sane: NET_START reply too short\n");
		goto out;
	}

	reply = sb_ptr;
	if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
		/* saned refused the command */
		pr_debug("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
			 ntohl(reply->status));
		goto out;
	}

	/* Invalid saned reply? Ignore it. */
	if (reply->zero != 0)
		goto out;

	exp = nf_ct_expect_alloc(ct);
	if (exp == NULL) {
		ret = NF_DROP;
		goto out;
	}

	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &tuple->src.u3, &tuple->dst.u3,
			  IPPROTO_TCP, NULL, &reply->port);

	pr_debug("nf_ct_sane: expect: ");
	nf_ct_dump_tuple(&exp->tuple);

	/* Can't expect this?  Best to drop packet now. */
	if (nf_ct_expect_related(exp) != 0)
		ret = NF_DROP;

	nf_ct_expect_put(exp);

out:
//.........这里部分代码省略.........

static int help(struct sk_buff *skb, unsigned int protoff,
		struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff;
	const struct iphdr *iph;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	const char *data_limit;
	char *data, *ib_ptr;
	int dir = CTINFO2DIR(ctinfo);
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_tuple *tuple;
	__be32 dcc_ip;
	u_int16_t dcc_port;
	__be16 port;
	int i, ret = NF_ACCEPT;
	char *addr_beg_p, *addr_end_p;
	typeof(nf_nat_irc_hook) nf_nat_irc;

	
	if (dir == IP_CT_DIR_REPLY)
		return NF_ACCEPT;

	
	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
		return NF_ACCEPT;

	
	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	
	dataoff = protoff + th->doff*4;
	if (dataoff >= skb->len)
		return NF_ACCEPT;

	spin_lock_bh(&irc_buffer_lock);
	ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
				    irc_buffer);
	BUG_ON(ib_ptr == NULL);

	data = ib_ptr;
	data_limit = ib_ptr + skb->len - dataoff;

	while (data < data_limit - (19 + MINMATCHLEN)) {
		if (memcmp(data, "\1DCC ", 5)) {
			data++;
			continue;
		}
		data += 5;
		

		iph = ip_hdr(skb);
		pr_debug("DCC found in master %pI4:%u %pI4:%u\n",
			 &iph->saddr, ntohs(th->source),
			 &iph->daddr, ntohs(th->dest));

		for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
			if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
				
				continue;
			}
			data += strlen(dccprotos[i]);
			pr_debug("DCC %s detected\n", dccprotos[i]);

			if (parse_dcc(data, data_limit, &dcc_ip,
				       &dcc_port, &addr_beg_p, &addr_end_p)) {
				pr_debug("unable to parse dcc command\n");
				continue;
			}

			pr_debug("DCC bound ip/port: %pI4:%u\n",
				 &dcc_ip, dcc_port);

			
			tuple = &ct->tuplehash[dir].tuple;
			if (tuple->src.u3.ip != dcc_ip &&
			    tuple->dst.u3.ip != dcc_ip) {
				if (net_ratelimit())
					printk(KERN_WARNING
						"Forged DCC command from %pI4: %pI4:%u\n",
						&tuple->src.u3.ip,
						&dcc_ip, dcc_port);
				continue;
			}

			exp = nf_ct_expect_alloc(ct);
			if (exp == NULL) {
				ret = NF_DROP;
				goto out;
			}
			tuple = &ct->tuplehash[!dir].tuple;
			port = htons(dcc_port);
			nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
					  tuple->src.l3num,
					  NULL, &tuple->dst.u3,
					  IPPROTO_TCP, NULL, &port);

			nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
//.........这里部分代码省略.........

static int tcp_packet(struct nf_conn *ct,
		      const struct sk_buff *skb,
		      unsigned int dataoff,
		      enum ip_conntrack_info ctinfo,
		      u_int8_t pf,
		      unsigned int hooknum,
		      unsigned int *timeouts)
{
	struct net *net = nf_ct_net(ct);
	struct nf_conntrack_tuple *tuple;
	enum tcp_conntrack new_state, old_state;
	enum ip_conntrack_dir dir;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	unsigned long timeout;
	unsigned int index;

	th = skb_header_pointer(skb, dataoff, sizeof(_tcph), &_tcph);
	BUG_ON(th == NULL);

	spin_lock_bh(&ct->lock);
	old_state = ct->proto.tcp.state;
	dir = CTINFO2DIR(ctinfo);
	index = get_conntrack_index(th);
	new_state = tcp_conntracks[dir][index][old_state];
	tuple = &ct->tuplehash[dir].tuple;

	switch (new_state) {
	case TCP_CONNTRACK_SYN_SENT:
		if (old_state < TCP_CONNTRACK_TIME_WAIT)
			break;
		if (((ct->proto.tcp.seen[dir].flags
		      | ct->proto.tcp.seen[!dir].flags)
		     & IP_CT_TCP_FLAG_CLOSE_INIT)
		    || (ct->proto.tcp.last_dir == dir
		        && ct->proto.tcp.last_index == TCP_RST_SET)) {
			spin_unlock_bh(&ct->lock);

			if (nf_ct_kill(ct))
				return -NF_REPEAT;
			return NF_DROP;
		}
		
	case TCP_CONNTRACK_IGNORE:
		if (index == TCP_SYNACK_SET
		    && ct->proto.tcp.last_index == TCP_SYN_SET
		    && ct->proto.tcp.last_dir != dir
		    && ntohl(th->ack_seq) == ct->proto.tcp.last_end) {
			old_state = TCP_CONNTRACK_SYN_SENT;
			new_state = TCP_CONNTRACK_SYN_RECV;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_end =
				ct->proto.tcp.last_end;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxend =
				ct->proto.tcp.last_end;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_maxwin =
				ct->proto.tcp.last_win == 0 ?
					1 : ct->proto.tcp.last_win;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].td_scale =
				ct->proto.tcp.last_wscale;
			ct->proto.tcp.seen[ct->proto.tcp.last_dir].flags =
				ct->proto.tcp.last_flags;
			memset(&ct->proto.tcp.seen[dir], 0,
			       sizeof(struct ip_ct_tcp_state));
			break;
		}
		ct->proto.tcp.last_index = index;
		ct->proto.tcp.last_dir = dir;
		ct->proto.tcp.last_seq = ntohl(th->seq);
		ct->proto.tcp.last_end =
		    segment_seq_plus_len(ntohl(th->seq), skb->len, dataoff, th);
		ct->proto.tcp.last_win = ntohs(th->window);

		if (index == TCP_SYN_SET && dir == IP_CT_DIR_ORIGINAL) {
			struct ip_ct_tcp_state seen = {};

			ct->proto.tcp.last_flags =
			ct->proto.tcp.last_wscale = 0;
			tcp_options(skb, dataoff, th, &seen);
			if (seen.flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
				ct->proto.tcp.last_flags |=
					IP_CT_TCP_FLAG_WINDOW_SCALE;
				ct->proto.tcp.last_wscale = seen.td_scale;
			}
			if (seen.flags & IP_CT_TCP_FLAG_SACK_PERM) {
				ct->proto.tcp.last_flags |=
					IP_CT_TCP_FLAG_SACK_PERM;
			}
		}
		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
				  "nf_ct_tcp: invalid packet ignored ");
		return NF_ACCEPT;
	case TCP_CONNTRACK_MAX:
		
		pr_debug("nf_ct_tcp: Invalid dir=%i index=%u ostate=%u\n",
			 dir, get_conntrack_index(th), old_state);
		spin_unlock_bh(&ct->lock);
		if (LOG_INVALID(net, IPPROTO_TCP))
			nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
//.........这里部分代码省略.........