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/*
* (C)opyright 1995 by Darren Reed.
*
* Redistribution and use in source and binary forms are permitted
* provided that this notice is preserved and due credit is given
* to the original author and the contributors.
*/
#ifndef lint
static char sccsid[] = "@(#)ip_state.c 1.6 3/24/96 (C) 1993-1995 Darren Reed";
#endif
#if !defined(_KERNEL) && !defined(KERNEL)
# include <stdlib.h>
# include <string.h>
#endif
#ifndef linux
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <sys/uio.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#if !defined(__SVR4) && !defined(__svr4__)
# include <sys/dir.h>
# include <sys/mbuf.h>
#else
# include <sys/byteorder.h>
# include <sys/dditypes.h>
# include <sys/stream.h>
# include <sys/kmem.h>
#endif
#include <net/if.h>
#ifdef sun
#include <net/af.h>
#endif
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/tcpip.h>
#include <netinet/ip_icmp.h>
#include <syslog.h>
#endif
#include "ip_fil.h"
#include "ip_state.h"
#ifndef MIN
#define MIN(a,b) (((a)<(b))?(a):(b))
#endif
#define TCP_CLOSE (TH_FIN|TH_RST)
ipstate_t *ips_table[IPSTATE_SIZE];
int ips_num = 0;
ips_stat_t ips_stats;
#if SOLARIS
extern kmutex_t ipf_state;
# if !defined(_KERNEL)
#define bcopy(a,b,c) memmove(b,a,c)
# endif
#endif
ips_stat_t *fr_statetstats()
{
ips_stats.iss_active = ips_num;
ips_stats.iss_table = ips_table;
return &ips_stats;
}
#define PAIRS(s1,d1,s2,d2) ((((s1) == (s2)) && ((d1) == (d2))) ||\
(((s1) == (d2)) && ((d1) == (s2))))
#define IPPAIR(s1,d1,s2,d2) PAIRS((s1).s_addr, (d1).s_addr, \
(s2).s_addr, (d2).s_addr)
/*
* Create a new ipstate structure and hang it off the hash table.
*/
int fr_addstate(ip, hlen, pass)
ip_t *ip;
int hlen;
u_int pass;
{
ipstate_t ips;
register ipstate_t *is = &ips;
register u_int hv;
if (ips_num == IPSTATE_MAX) {
ips_stats.iss_max++;
return -1;
}
/*
* Copy and calculate...
*/
hv = (is->is_p = ip->ip_p);
hv += (is->is_src.s_addr = ip->ip_src.s_addr);
hv += (is->is_dst.s_addr = ip->ip_dst.s_addr);
switch (ip->ip_p)
{
case IPPROTO_ICMP :
{
struct icmp *ic = (struct icmp *)((char *)ip + hlen);
switch (ic->icmp_type)
{
case ICMP_ECHO :
is->is_icmp.ics_type = 0;
hv += (is->is_icmp.ics_id = ic->icmp_id);
hv += (is->is_icmp.ics_seq = ic->icmp_seq);
break;
case ICMP_TSTAMP :
case ICMP_IREQ :
case ICMP_MASKREQ :
is->is_icmp.ics_type = ic->icmp_type + 1;
break;
default :
return -1;
}
ips_stats.iss_icmp++;
is->is_age = 120;
break;
}
case IPPROTO_TCP :
{
register tcphdr_t *tcp = (tcphdr_t *)((char *)ip + hlen);
/*
* The endian of the ports doesn't matter, but the ack and
* sequence numbers do as we do mathematics on them later.
*/
hv += (is->is_dport = tcp->th_dport);
hv += (is->is_sport = tcp->th_sport);
is->is_seq = ntohl(tcp->th_seq);
is->is_ack = ntohl(tcp->th_ack);
is->is_win = ntohs(tcp->th_win);
ips_stats.iss_tcp++;
/*
* If we're creating state for a starting connectoin, start the
* timer on it as we'll never see an error if it fails to
* connect.
*/
if ((tcp->th_flags & (TH_SYN|TH_ACK)) == TH_SYN)
is->is_age = 120;
else
is->is_age = 0;
break;
}
case IPPROTO_UDP :
{
register tcphdr_t *tcp = (tcphdr_t *)((char *)ip + hlen);
hv += (is->is_dport = tcp->th_dport);
hv += (is->is_sport = tcp->th_sport);
ips_stats.iss_udp++;
is->is_age = 120;
break;
}
default :
return -1;
}
if (!(is = (ipstate_t *)KMALLOC(sizeof(*is)))) {
ips_stats.iss_nomem++;
return -1;
}
bcopy((char *)&ips, (char *)is, sizeof(*is));
hv %= IPSTATE_SIZE;
MUTEX_ENTER(&ipf_state);
is->is_next = ips_table[hv];
ips_table[hv] = is;
is->is_pass = pass & ~(FR_LOGFIRST|FR_LOG);
ips_num++;
MUTEX_EXIT(&ipf_state);
return 0;
}
/*
* Check if a packet has a registered state.
*/
int fr_checkstate(ip, fin)
ip_t *ip;
fr_info_t *fin;
{
register struct in_addr dst, src;
register ipstate_t *is, **isp;
register u_char pr;
struct icmp *ic;
tcphdr_t *tcp;
u_int hv, hlen;
if ((ip->ip_off & 0x1fff) && !(fin->fin_fi.fi_fl & FI_SHORT))
return 0;
hlen = fin->fin_hlen;
tcp = (tcphdr_t *)((char *)ip + hlen);
ic = (struct icmp *)tcp;
hv = (pr = ip->ip_p);
hv += (src.s_addr = ip->ip_src.s_addr);
hv += (dst.s_addr = ip->ip_dst.s_addr);
/*
* Search the hash table for matching packet header info.
*/
switch (ip->ip_p)
{
case IPPROTO_ICMP :
hv += ic->icmp_id;
hv += ic->icmp_seq;
hv %= IPSTATE_SIZE;
MUTEX_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_next)
if ((is->is_p == pr) &&
(ic->icmp_id == is->is_icmp.ics_id) &&
(ic->icmp_seq == is->is_icmp.ics_seq) &&
IPPAIR(src, dst, is->is_src, is->is_dst)) {
/*
* If we have type 0 stored, allow any icmp
* replies through.
*/
if (is->is_icmp.ics_type &&
is->is_icmp.ics_type != ic->icmp_type)
continue;
is->is_age = 120;
ips_stats.iss_hits++;
MUTEX_EXIT(&ipf_state);
return is->is_pass;
}
MUTEX_EXIT(&ipf_state);
break;
case IPPROTO_TCP :
{
register u_short dport = tcp->th_dport, sport = tcp->th_sport;
register u_short win = ntohs(tcp->th_win);
tcp_seq seq, ack;
hv += dport;
hv += sport;
hv %= IPSTATE_SIZE;
MUTEX_ENTER(&ipf_state);
for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_next) {
register int dl, seqskew, ackskew;
if ((is->is_p == pr) &&
PAIRS(sport, dport, is->is_sport, is->is_dport) &&
IPPAIR(src, dst, is->is_src, is->is_dst)) {
dl = ip->ip_len - hlen - sizeof(tcphdr_t);
/*
* Find difference between last checked packet
* and this packet.
*/
seq = ntohl(tcp->th_seq);
ack = ntohl(tcp->th_ack);
if (sport == is->is_sport) {
seqskew = seq - is->is_seq;
ackskew = ack - is->is_ack;
} else {
seqskew = ack - is->is_seq;
if (!is->is_ack) {
/*
* Must be a SYN-ACK in reply
* to a SYN. Set age timeout
* to 0 to stop deletion.
*/
is->is_ack = seq;
is->is_age = 0;
}
ackskew = seq - is->is_ack;
}
/*
* Make skew values absolute
*/
if (seqskew < 0)
seqskew = -seqskew;
if (ackskew < 0)
ackskew = -ackskew;
/*
* If the difference in sequence and ack
* numbers is within the window size of the
* connection, store these values and match
* the packet.
*/
if ((seqskew <= win) && (ackskew <= win)) {
is->is_win = win;
if (sport == is->is_sport) {
is->is_seq = seq;
is->is_ack = ack;
} else {
is->is_seq = ack;
is->is_ack = seq;
}
ips_stats.iss_hits++;
/*
* Nearing end of connection, start
* timeout.
*/
#ifdef _KERNEL
if ((tcp->th_flags & TCP_CLOSE) &&
!is->is_age)
is->is_age = 120;
MUTEX_EXIT(&ipf_state);
return is->is_pass;
#else
if (tcp->th_flags & TCP_CLOSE) {
int pass = is->is_pass;
*isp = is->is_next;
isp = &ips_table[hv];
KFREE(is);
return pass;
}
return is->is_pass;
#endif
}
}
}
MUTEX_EXIT(&ipf_state);
break;
}
case IPPROTO_UDP :
{
register u_short dport = tcp->th_dport, sport = tcp->th_sport;
hv += dport;
hv += sport;
hv %= IPSTATE_SIZE;
/*
* Nothing else to match on but ports. and IP#'s
*/
MUTEX_ENTER(&ipf_state);
for (is = ips_table[hv]; is; is = is->is_next)
if ((is->is_p == pr) &&
PAIRS(sport, dport, is->is_sport, is->is_dport) &&
IPPAIR(src, dst, is->is_src, is->is_dst)) {
ips_stats.iss_hits++;
is->is_age = 120;
MUTEX_EXIT(&ipf_state);
return is->is_pass;
}
MUTEX_EXIT(&ipf_state);
break;
}
default :
break;
}
ips_stats.iss_miss++;
return 0;
}
/*
* Free memory in use by all state info. kept.
*/
void fr_stateunload()
{
register int i;
register ipstate_t *is, **isp;
MUTEX_ENTER(&ipf_state);
for (i = 0; i < IPSTATE_SIZE; i++)
for (isp = &ips_table[i]; (is = *isp); ) {
*isp = is->is_next;
KFREE(is);
}
MUTEX_EXIT(&ipf_state);
}
/*
* Slowly expire held state for thingslike UDP and ICMP. Timeouts are set
* in expectation of this being called twice per second.
*/
void fr_timeoutstate()
{
register int i;
register ipstate_t *is, **isp;
MUTEX_ENTER(&ipf_state);
for (i = 0; i < IPSTATE_SIZE; i++)
for (isp = &ips_table[i]; (is = *isp); )
if (is->is_age && !--is->is_age) {
*isp = is->is_next;
if (is->is_p == IPPROTO_TCP)
ips_stats.iss_fin++;
else
ips_stats.iss_expire++;
KFREE(is);
ips_num--;
} else
isp = &is->is_next;
MUTEX_EXIT(&ipf_state);
}
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