543 lines
12 KiB
C
543 lines
12 KiB
C
/*
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* (C)opyright 1995 by Darren Reed.
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*
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* Redistribution and use in source and binary forms are permitted
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* provided that this notice is preserved and due credit is given
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* to the original author and the contributors.
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*/
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#if !defined(lint) && defined(LIBC_SCCS)
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static char sccsid[] = "@(#)ip_state.c 1.8 6/5/96 (C) 1993-1995 Darren Reed";
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static char rcsid[] = "$Id: ip_state.c,v 2.0.1.3 1997/02/16 06:18:36 darrenr Exp $";
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#endif
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#if !defined(_KERNEL) && !defined(KERNEL)
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# include <stdlib.h>
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# include <string.h>
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#endif
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#include <sys/errno.h>
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/file.h>
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#include <sys/ioctl.h>
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#include <sys/uio.h>
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#ifdef _KERNEL
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# include <sys/systm.h>
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#endif
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#if !defined(__SVR4) && !defined(__svr4__)
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# include <sys/mbuf.h>
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#else
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# include <sys/byteorder.h>
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# include <sys/dditypes.h>
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# include <sys/stream.h>
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# include <sys/kmem.h>
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#endif
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#include <net/if.h>
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#ifdef sun
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#include <net/af.h>
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#endif
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/udp.h>
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#include <netinet/tcpip.h>
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#include <netinet/ip_icmp.h>
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#include "ip_fil.h"
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#include "ip_compat.h"
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#include "ip_state.h"
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#ifndef MIN
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#define MIN(a,b) (((a)<(b))?(a):(b))
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#endif
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void set_tcp_age();
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#define TCP_CLOSE (TH_FIN|TH_RST)
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ipstate_t *ips_table[IPSTATE_SIZE];
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int ips_num = 0;
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ips_stat_t ips_stats;
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#if SOLARIS
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extern kmutex_t ipf_state;
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# if !defined(_KERNEL)
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#define bcopy(a,b,c) memmove(b,a,c)
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# endif
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#endif
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#define FIVE_DAYS (2 * 5 * 86400) /* 5 days: half closed session */
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u_long fr_tcpidletimeout = FIVE_DAYS,
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fr_tcpclosewait = 60,
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fr_tcplastack = 20,
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fr_tcptimeout = 120,
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fr_tcpclosed = 1,
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fr_udptimeout = 120,
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fr_icmptimeout = 120;
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ips_stat_t *fr_statetstats()
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{
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ips_stats.iss_active = ips_num;
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ips_stats.iss_table = ips_table;
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return &ips_stats;
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}
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#define PAIRS(s1,d1,s2,d2) ((((s1) == (s2)) && ((d1) == (d2))) ||\
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(((s1) == (d2)) && ((d1) == (s2))))
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#define IPPAIR(s1,d1,s2,d2) PAIRS((s1).s_addr, (d1).s_addr, \
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(s2).s_addr, (d2).s_addr)
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/*
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* Create a new ipstate structure and hang it off the hash table.
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*/
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int fr_addstate(ip, fin, pass)
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ip_t *ip;
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fr_info_t *fin;
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u_int pass;
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{
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ipstate_t ips;
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register ipstate_t *is = &ips;
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register u_int hv;
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if ((ip->ip_off & 0x1fff) || (fin->fin_fi.fi_fl & FI_SHORT))
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return -1;
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if (ips_num == IPSTATE_MAX) {
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ips_stats.iss_max++;
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return -1;
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}
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ips.is_age = 1;
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ips.is_state[0] = 0;
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ips.is_state[1] = 0;
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/*
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* Copy and calculate...
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*/
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hv = (is->is_p = ip->ip_p);
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hv += (is->is_src.s_addr = ip->ip_src.s_addr);
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hv += (is->is_dst.s_addr = ip->ip_dst.s_addr);
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switch (ip->ip_p)
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{
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case IPPROTO_ICMP :
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{
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struct icmp *ic = (struct icmp *)fin->fin_dp;
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switch (ic->icmp_type)
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{
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case ICMP_ECHO :
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is->is_icmp.ics_type = 0;
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hv += (is->is_icmp.ics_id = ic->icmp_id);
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hv += (is->is_icmp.ics_seq = ic->icmp_seq);
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break;
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case ICMP_TSTAMP :
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case ICMP_IREQ :
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case ICMP_MASKREQ :
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is->is_icmp.ics_type = ic->icmp_type + 1;
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break;
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default :
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return -1;
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}
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ips_stats.iss_icmp++;
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is->is_age = fr_icmptimeout;
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break;
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}
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case IPPROTO_TCP :
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{
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register tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
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/*
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* The endian of the ports doesn't matter, but the ack and
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* sequence numbers do as we do mathematics on them later.
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*/
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hv += (is->is_dport = tcp->th_dport);
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hv += (is->is_sport = tcp->th_sport);
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is->is_seq = ntohl(tcp->th_seq);
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is->is_ack = ntohl(tcp->th_ack);
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is->is_swin = ntohs(tcp->th_win);
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is->is_dwin = is->is_swin; /* start them the same */
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ips_stats.iss_tcp++;
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/*
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* If we're creating state for a starting connectoin, start the
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* timer on it as we'll never see an error if it fails to
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* connect.
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*/
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if ((tcp->th_flags & (TH_SYN|TH_ACK)) == TH_SYN)
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is->is_ack = 0; /* Trumpet WinSock 'ism */
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set_tcp_age(&is->is_age, is->is_state, ip, fin,
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tcp->th_sport == is->is_sport);
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break;
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}
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case IPPROTO_UDP :
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{
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register tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
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hv += (is->is_dport = tcp->th_dport);
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hv += (is->is_sport = tcp->th_sport);
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ips_stats.iss_udp++;
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is->is_age = fr_udptimeout;
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break;
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}
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default :
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return -1;
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}
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if (!(is = (ipstate_t *)KMALLOC(sizeof(*is)))) {
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ips_stats.iss_nomem++;
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return -1;
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}
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bcopy((char *)&ips, (char *)is, sizeof(*is));
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hv %= IPSTATE_SIZE;
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MUTEX_ENTER(&ipf_state);
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is->is_next = ips_table[hv];
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ips_table[hv] = is;
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is->is_pass = pass;
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if (pass & FR_LOGFIRST)
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is->is_pass &= ~(FR_LOGFIRST|FR_LOG);
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ips_num++;
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MUTEX_EXIT(&ipf_state);
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return 0;
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}
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/*
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* check to see if a packet with TCP headers fits within the TCP window.
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* change timeout depending on whether new packet is a SYN-ACK returning for a
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* SYN or a RST or FIN which indicate time to close up shop.
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*/
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int fr_tcpstate(is, fin, ip, tcp, sport
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#ifndef _KERNEL
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,isp)
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ipstate_t **isp;
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#else
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)
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#endif
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register ipstate_t *is;
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fr_info_t *fin;
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ip_t *ip;
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tcphdr_t *tcp;
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u_short sport;
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{
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register int seqskew, ackskew;
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register u_short swin, dwin;
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register tcp_seq seq, ack;
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int source;
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/*
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* Find difference between last checked packet and this packet.
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*/
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seq = ntohl(tcp->th_seq);
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ack = ntohl(tcp->th_ack);
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if (sport == is->is_sport) {
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seqskew = seq - is->is_seq;
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ackskew = ack - is->is_ack;
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} else {
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seqskew = ack - is->is_seq;
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if (!is->is_ack)
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/*
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* Must be a SYN-ACK in reply to a SYN.
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*/
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is->is_ack = seq;
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ackskew = seq - is->is_ack;
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}
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/*
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* Make skew values absolute
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*/
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if (seqskew < 0)
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seqskew = -seqskew;
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if (ackskew < 0)
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ackskew = -ackskew;
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/*
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* If the difference in sequence and ack numbers is within the
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* window size of the connection, store these values and match
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* the packet.
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*/
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if ((source = (sport == is->is_sport))) {
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swin = is->is_swin;
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dwin = is->is_dwin;
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} else {
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dwin = is->is_swin;
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swin = is->is_dwin;
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}
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if ((seqskew <= swin) && (ackskew <= dwin)) {
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if (source) {
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is->is_seq = seq;
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is->is_ack = ack;
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is->is_swin = ntohs(tcp->th_win);
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} else {
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is->is_seq = ack;
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is->is_ack = seq;
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is->is_dwin = ntohs(tcp->th_win);
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}
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ips_stats.iss_hits++;
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/*
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* Nearing end of connection, start timeout.
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*/
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set_tcp_age(&is->is_age, is->is_state, ip, fin,
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tcp->th_sport == is->is_sport);
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return 1;
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}
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return 0;
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}
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/*
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* Check if a packet has a registered state.
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*/
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int fr_checkstate(ip, fin)
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ip_t *ip;
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fr_info_t *fin;
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{
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register struct in_addr dst, src;
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register ipstate_t *is, **isp;
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register u_char pr;
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struct icmp *ic;
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tcphdr_t *tcp;
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u_int hv, hlen;
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if ((ip->ip_off & 0x1fff) || (fin->fin_fi.fi_fl & FI_SHORT))
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return 0;
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hlen = fin->fin_hlen;
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tcp = (tcphdr_t *)((char *)ip + hlen);
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ic = (struct icmp *)tcp;
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hv = (pr = ip->ip_p);
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hv += (src.s_addr = ip->ip_src.s_addr);
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hv += (dst.s_addr = ip->ip_dst.s_addr);
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/*
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* Search the hash table for matching packet header info.
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*/
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switch (ip->ip_p)
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{
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case IPPROTO_ICMP :
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hv += ic->icmp_id;
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hv += ic->icmp_seq;
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hv %= IPSTATE_SIZE;
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MUTEX_ENTER(&ipf_state);
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for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_next)
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if ((is->is_p == pr) &&
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(ic->icmp_id == is->is_icmp.ics_id) &&
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(ic->icmp_seq == is->is_icmp.ics_seq) &&
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IPPAIR(src, dst, is->is_src, is->is_dst)) {
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/*
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* If we have type 0 stored, allow any icmp
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* replies through.
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*/
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if (is->is_icmp.ics_type &&
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is->is_icmp.ics_type != ic->icmp_type)
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continue;
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is->is_age = fr_icmptimeout;
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ips_stats.iss_hits++;
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MUTEX_EXIT(&ipf_state);
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return is->is_pass;
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}
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MUTEX_EXIT(&ipf_state);
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break;
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case IPPROTO_TCP :
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{
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register u_short dport = tcp->th_dport, sport = tcp->th_sport;
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hv += dport;
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hv += sport;
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hv %= IPSTATE_SIZE;
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MUTEX_ENTER(&ipf_state);
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for (isp = &ips_table[hv]; (is = *isp); isp = &is->is_next) {
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if ((is->is_p == pr) &&
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PAIRS(sport, dport, is->is_sport, is->is_dport) &&
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IPPAIR(src, dst, is->is_src, is->is_dst))
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if (fr_tcpstate(is, fin, ip, tcp, sport)) {
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#ifdef _KERNEL
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MUTEX_EXIT(&ipf_state);
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return is->is_pass;
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#else
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int pass = is->is_pass;
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if (tcp->th_flags & TCP_CLOSE) {
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*isp = is->is_next;
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isp = &ips_table[hv];
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KFREE(is);
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}
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return pass;
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#endif
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}
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}
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MUTEX_EXIT(&ipf_state);
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break;
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}
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case IPPROTO_UDP :
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{
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register u_short dport = tcp->th_dport, sport = tcp->th_sport;
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hv += dport;
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hv += sport;
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hv %= IPSTATE_SIZE;
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/*
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* Nothing else to match on but ports. and IP#'s
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*/
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MUTEX_ENTER(&ipf_state);
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for (is = ips_table[hv]; is; is = is->is_next)
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if ((is->is_p == pr) &&
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PAIRS(sport, dport, is->is_sport, is->is_dport) &&
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IPPAIR(src, dst, is->is_src, is->is_dst)) {
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ips_stats.iss_hits++;
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is->is_age = fr_udptimeout;
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MUTEX_EXIT(&ipf_state);
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return is->is_pass;
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}
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MUTEX_EXIT(&ipf_state);
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break;
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}
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default :
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break;
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}
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ips_stats.iss_miss++;
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return 0;
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}
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/*
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* Free memory in use by all state info. kept.
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*/
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void fr_stateunload()
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{
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register int i;
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register ipstate_t *is, **isp;
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int s;
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MUTEX_ENTER(&ipf_state);
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SPLNET(s);
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for (i = 0; i < IPSTATE_SIZE; i++)
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for (isp = &ips_table[i]; (is = *isp); ) {
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*isp = is->is_next;
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KFREE(is);
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}
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SPLX(s);
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MUTEX_EXIT(&ipf_state);
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}
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/*
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* Slowly expire held state for thingslike UDP and ICMP. Timeouts are set
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* in expectation of this being called twice per second.
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*/
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void fr_timeoutstate()
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{
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register int i;
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register ipstate_t *is, **isp;
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int s;
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MUTEX_ENTER(&ipf_state);
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SPLNET(s);
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for (i = 0; i < IPSTATE_SIZE; i++)
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for (isp = &ips_table[i]; (is = *isp); )
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if (is->is_age && !--is->is_age) {
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*isp = is->is_next;
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if (is->is_p == IPPROTO_TCP)
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ips_stats.iss_fin++;
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else
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ips_stats.iss_expire++;
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KFREE(is);
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ips_num--;
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} else
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isp = &is->is_next;
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SPLX(s);
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MUTEX_EXIT(&ipf_state);
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}
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/*
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* Original idea freom Pradeep Krishnan for use primarily with NAT code.
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* (pkrishna@netcom.com)
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*/
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void set_tcp_age(age, state, ip, fin, dir)
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int *age;
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u_char *state;
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ip_t *ip;
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fr_info_t *fin;
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int dir;
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{
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tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
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u_char flags = tcp->th_flags;
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int dlen, ostate;
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ostate = state[1 - dir];
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dlen = ip->ip_len - fin->fin_hlen - (tcp->th_off << 2);
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if (flags & TH_RST) {
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if (!(tcp->th_flags & TH_PUSH) && !dlen) {
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*age = fr_tcpclosed;
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state[dir] = TCPS_CLOSED;
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} else {
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*age = fr_tcpclosewait;
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state[dir] = TCPS_CLOSE_WAIT;
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}
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return;
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}
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*age = fr_tcptimeout; /* 1 min */
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switch(state[dir])
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{
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case TCPS_FIN_WAIT_2:
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case TCPS_CLOSED:
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if ((flags & TH_OPENING) == TH_OPENING)
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state[dir] = TCPS_SYN_RECEIVED;
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else if (flags & TH_SYN)
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state[dir] = TCPS_SYN_SENT;
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break;
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case TCPS_SYN_RECEIVED:
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if ((flags & (TH_FIN|TH_ACK)) == TH_ACK) {
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state[dir] = TCPS_ESTABLISHED;
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*age = fr_tcpidletimeout;
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}
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break;
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case TCPS_SYN_SENT:
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if ((flags & (TH_FIN|TH_ACK)) == TH_ACK) {
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state[dir] = TCPS_ESTABLISHED;
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*age = fr_tcpidletimeout;
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}
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break;
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case TCPS_ESTABLISHED:
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if (flags & TH_FIN) {
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state[dir] = TCPS_CLOSE_WAIT;
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|
if (!(flags & TH_PUSH) && !dlen &&
|
|
ostate > TCPS_ESTABLISHED)
|
|
*age = fr_tcplastack;
|
|
else
|
|
*age = fr_tcpclosewait;
|
|
} else
|
|
*age = fr_tcpidletimeout;
|
|
break;
|
|
case TCPS_CLOSE_WAIT:
|
|
if ((flags & TH_FIN) && !(flags & TH_PUSH) && !dlen &&
|
|
ostate > TCPS_ESTABLISHED) {
|
|
*age = fr_tcplastack;
|
|
state[dir] = TCPS_LAST_ACK;
|
|
} else
|
|
*age = fr_tcpclosewait;
|
|
break;
|
|
case TCPS_LAST_ACK:
|
|
if (flags & TH_ACK) {
|
|
state[dir] = TCPS_FIN_WAIT_2;
|
|
if (!(flags & TH_PUSH) && !dlen &&
|
|
ostate > TCPS_ESTABLISHED)
|
|
*age = fr_tcplastack;
|
|
else {
|
|
*age = fr_tcpclosewait;
|
|
state[dir] = TCPS_CLOSE_WAIT;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|