ip_ftp_pxy.c

/*
 * Simple FTP transparent proxy for in-kernel use.  For use with the NAT
 * code.
 *
 * $Id$
 */
#if SOLARIS && defined(_KERNEL)
extern	kmutex_t	ipf_rw;
#endif

#define	isdigit(x)	((x) >= '0' && (x) <= '9')
#define	isupper(x)	(((unsigned)(x) >= 'A') && ((unsigned)(x) <= 'Z'))
#define	islower(x)	(((unsigned)(x) >= 'a') && ((unsigned)(x) <= 'z'))
#define	isalpha(x)	(isupper(x) || islower(x))
#define	toupper(x)	(isupper(x) ? (x) : (x) - 'a' + 'A')

#define	IPF_FTP_PROXY

#define	IPF_MINPORTLEN	18
#define	IPF_MAXPORTLEN	30
#define	IPF_MIN227LEN	39
#define	IPF_MAX227LEN	51
#define	IPF_FTPBUFSZ	96	/* This *MUST* be >= 53! */

#define	FTPXY_GO	0
#define	FTPXY_INIT	1
#define	FTPXY_USER_1	2
#define	FTPXY_USOK_1	3
#define	FTPXY_PASS_1	4
#define	FTPXY_PAOK_1	5
#define	FTPXY_AUTH_1	6
#define	FTPXY_AUOK_1	7
#define	FTPXY_ADAT_1	8
#define	FTPXY_ADOK_1	9
#define	FTPXY_ACCT_1	10
#define	FTPXY_ACOK_1	11
#define	FTPXY_USER_2	12
#define	FTPXY_USOK_2	13
#define	FTPXY_PASS_2	14
#define	FTPXY_PAOK_2	15

/*
 * Values for FTP commands.  Numerics cover 0-999
 */
#define	FTPXY_C_PASV	1000

int ippr_ftp_client __P((fr_info_t *, ip_t *, nat_t *, ftpinfo_t *, int));
int ippr_ftp_complete __P((char *, size_t));
int ippr_ftp_in __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *));
int ippr_ftp_init __P((void));
int ippr_ftp_new __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *));
int ippr_ftp_out __P((fr_info_t *, ip_t *, ap_session_t *, nat_t *));
int ippr_ftp_pasv __P((fr_info_t *, ip_t *, nat_t *, ftpinfo_t *, int));
int ippr_ftp_port __P((fr_info_t *, ip_t *, nat_t *, ftpside_t *, int));
int ippr_ftp_process __P((fr_info_t *, ip_t *, nat_t *, ftpinfo_t *, int));
int ippr_ftp_server __P((fr_info_t *, ip_t *, nat_t *, ftpinfo_t *, int));
int ippr_ftp_valid __P((ftpinfo_t *, int, char *, size_t));
int ippr_ftp_server_valid __P((ftpside_t *, char *, size_t));
int ippr_ftp_client_valid __P((ftpside_t *, char *, size_t));
u_short ippr_ftp_atoi __P((char **));

static	frentry_t	ftppxyfr;
int	ippr_ftp_pasvonly = 0;
int	ippr_ftp_insecure = 0;
int	ippr_ftp_forcepasv = 0;


/*
 * Initialize local structures.
 */
int ippr_ftp_init()
{
	bzero((char *)&ftppxyfr, sizeof(ftppxyfr));
	ftppxyfr.fr_ref = 1;
	ftppxyfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
	return 0;
}


int ippr_ftp_new(fin, ip, aps, nat)
fr_info_t *fin;
ip_t *ip;
ap_session_t *aps;
nat_t *nat;
{
	ftpinfo_t *ftp;
	ftpside_t *f;

	KMALLOC(ftp, ftpinfo_t *);
	if (ftp == NULL)
		return -1;
	aps->aps_data = ftp;
	aps->aps_psiz = sizeof(ftpinfo_t);

	bzero((char *)ftp, sizeof(*ftp));
	f = &ftp->ftp_side[0];
	f->ftps_rptr = f->ftps_buf;
	f->ftps_wptr = f->ftps_buf;
	f = &ftp->ftp_side[1];
	f->ftps_rptr = f->ftps_buf;
	f->ftps_wptr = f->ftps_buf;
	ftp->ftp_passok = FTPXY_INIT;
	return 0;
}


int ippr_ftp_port(fin, ip, nat, f, dlen)
fr_info_t *fin;
ip_t *ip;
nat_t *nat;
ftpside_t *f;
int dlen;
{
	tcphdr_t *tcp, tcph, *tcp2 = &tcph;
	char newbuf[IPF_FTPBUFSZ], *s;
	u_int a1, a2, a3, a4;
	struct in_addr swip;
	u_short a5, a6, sp;
	size_t nlen, olen;
	fr_info_t fi;
	int inc, off;
	nat_t *ipn;
	mb_t *m;
#if	SOLARIS && defined(_KERNEL)
	mb_t *m1;
#endif

	tcp = (tcphdr_t *)fin->fin_dp;
	/*
	 * Check for client sending out PORT message.
	 */
	if (dlen < IPF_MINPORTLEN) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout,
			"ippr_ftp_port:dlen(%d) < IPF_MINPORTLEN\n", dlen);
#endif
		return 0;
	}
	off = fin->fin_hlen + (tcp->th_off << 2);
	/*
	 * Skip the PORT command + space
	 */
	s = f->ftps_rptr + 5;
	/*
	 * Pick out the address components, two at a time.
	 */
	a1 = ippr_ftp_atoi(&s);
	if (s == NULL) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_port:ippr_ftp_atoi(1) failed\n");
#endif
		return 0;
	}
	a2 = ippr_ftp_atoi(&s);
	if (s == NULL) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_port:ippr_ftp_atoi(2) failed\n");
#endif
		return 0;
	}
	/*
	 * check that IP address in the PORT/PASV reply is the same as the
	 * sender of the command - prevents using PORT for port scanning.
	 */
	a1 <<= 16;
	a1 |= a2;
	if (a1 != ntohl(nat->nat_inip.s_addr)) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_port:a1 != nat->nat_inip\n");
#endif
		return 0;
	}

	a5 = ippr_ftp_atoi(&s);
	if (s == NULL) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_port:ippr_ftp_atoi(3) failed\n");
#endif
		return 0;
	}
	if (*s == ')')
		s++;

	/*
	 * check for CR-LF at the end.
	 */
	if (*s == '\n')
		s--;
	if ((*s == '\r') && (*(s + 1) == '\n')) {
		s += 2;
		a6 = a5 & 0xff;
	} else {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_port:missing cr-lf\n");
#endif
		return 0;
	}
	a5 >>= 8;
	a5 &= 0xff;
	/*
	 * Calculate new address parts for PORT command
	 */
	a1 = ntohl(ip->ip_src.s_addr);
	a2 = (a1 >> 16) & 0xff;
	a3 = (a1 >> 8) & 0xff;
	a4 = a1 & 0xff;
	a1 >>= 24;
	olen = s - f->ftps_rptr;
	/* DO NOT change this to snprintf! */
#if defined(OpenBSD) && (200311 >= 200311)
	(void) snprintf(newbuf, sizeof(newbuf), "%s %u,%u,%u,%u,%u,%u\r\n",
		        "PORT", a1, a2, a3, a4, a5, a6);
#else
	(void) sprintf(newbuf, "%s %u,%u,%u,%u,%u,%u\r\n",
		       "PORT", a1, a2, a3, a4, a5, a6);
#endif

	nlen = strlen(newbuf);
	inc = nlen - olen;
	if ((inc + ip->ip_len) > 65535) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout,
			"ippr_ftp_port:inc(%d) + ip->ip_len > 65535\n", inc);
#endif
		return 0;
	}

#if !defined(_KERNEL)
	m = *fin->fin_mp;
	bcopy(newbuf, (char *)m + off, nlen);
#else
# if SOLARIS
	m = fin->fin_qfm;
	for (m1 = m; m1->b_cont; m1 = m1->b_cont)
		;
	if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) {
		mblk_t *nm;

		/* alloc enough to keep same trailer space for lower driver */
		nm = allocb(nlen, BPRI_MED);
		PANIC((!nm),("ippr_ftp_out: allocb failed"));

		nm->b_band = m1->b_band;
		nm->b_wptr += nlen;

		m1->b_wptr -= olen;
		PANIC((m1->b_wptr < m1->b_rptr),
		      ("ippr_ftp_out: cannot handle fragmented data block"));

		linkb(m1, nm);
	} else {
		if (m1->b_datap->db_struiolim == m1->b_wptr)
			m1->b_datap->db_struiolim += inc;
		m1->b_datap->db_struioflag &= ~STRUIO_IP;
		m1->b_wptr += inc;
	}
	copyin_mblk(m, off, nlen, newbuf);
# else
	m = *fin->fin_mp;
	if (inc < 0)
		m_adj(m, inc);
	/* the mbuf chain will be extended if necessary by m_copyback() */
	m_copyback(m, off, nlen, newbuf);
#  ifdef	M_PKTHDR
	if (!(m->m_flags & M_PKTHDR))
		m->m_pkthdr.len += inc;
#  endif
# endif
#endif
	if (inc != 0) {
#if ((SOLARIS || defined(__sgi)) && defined(_KERNEL)) || !defined(_KERNEL)
		register u_32_t	sum1, sum2;

		sum1 = ip->ip_len;
		sum2 = ip->ip_len + inc;

		/* Because ~1 == -2, We really need ~1 == -1 */
		if (sum1 > sum2)
			sum2--;
		sum2 -= sum1;
		sum2 = (sum2 & 0xffff) + (sum2 >> 16);

		fix_outcksum(fin, &ip->ip_sum, sum2);
#endif
		ip->ip_len += inc;
	}

	/*
	 * Add skeleton NAT entry for connection which will come back the
	 * other way.
	 */
	sp = (a5 << 8 | a6);
	/*
	 * Don't allow the PORT command to specify a port < 1024 due to
	 * security crap.
	 */
	if (sp < 1024) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_port:sp(%d) < 1024\n", sp);
#endif
		return 0;
	}

	/*
	 * The server may not make the connection back from port 20, but
	 * it is the most likely so use it here to check for a conflicting
	 * mapping.
	 */
	bcopy((char *)fin, (char *)&fi, sizeof(fi));
	fi.fin_data[0] = sp;
	fi.fin_data[1] = fin->fin_data[1] - 1;
	ipn = nat_outlookup(&fi, IPN_TCP, nat->nat_p, nat->nat_inip,
			    ip->ip_dst, 0);
	if (ipn == NULL) {
		int slen;

		slen = ip->ip_len;
		ip->ip_len = fin->fin_hlen + sizeof(*tcp2);
		bzero((char *)tcp2, sizeof(*tcp2));
		tcp2->th_win = htons(8192);
		tcp2->th_sport = htons(sp);
		tcp2->th_off = 5;
		tcp2->th_flags = TH_SYN;
		tcp2->th_dport = 0; /* XXX - don't specify remote port */
		fi.fin_data[1] = 0;
		fi.fin_dlen = sizeof(*tcp2);
		fi.fin_dp = (char *)tcp2;
		fi.fin_fr = &ftppxyfr;
		fi.fin_out = 1;
		swip = ip->ip_src;
		fi.fin_fi.fi_saddr = nat->nat_inip.s_addr;
		ip->ip_src = nat->nat_inip;
		ipn = nat_new(&fi, ip, nat->nat_ptr, NULL, IPN_TCP|FI_W_DPORT,
			      NAT_OUTBOUND);
		if (ipn != NULL) {
			ipn->nat_age = fr_defnatage;
			(void) fr_addstate(ip, &fi, NULL,
					   FI_W_DPORT|FI_IGNOREPKT);
		}
		ip->ip_len = slen;
		ip->ip_src = swip;
	}
	return inc;
}


int ippr_ftp_client(fin, ip, nat, ftp, dlen)
fr_info_t *fin;
nat_t *nat;
ftpinfo_t *ftp;
ip_t *ip;
int dlen;
{
	char *rptr, *wptr, cmd[6], c;
	ftpside_t *f;
	int inc, i;

	inc = 0;
	f = &ftp->ftp_side[0];
	rptr = f->ftps_rptr;
	wptr = f->ftps_wptr;

	for (i = 0; (i < 5) && (i < dlen); i++) {
		c = rptr[i];
		if (isalpha(c)) {
			cmd[i] = toupper(c);
		} else {
			cmd[i] = c;
		}
	}
	cmd[i] = '\0';

	ftp->ftp_incok = 0;
	if (!strncmp(cmd, "USER ", 5) || !strncmp(cmd, "XAUT ", 5)) {
		if (ftp->ftp_passok == FTPXY_ADOK_1 ||
		    ftp->ftp_passok == FTPXY_AUOK_1) {
			ftp->ftp_passok = FTPXY_USER_2;
			ftp->ftp_incok = 1;
		} else {
			ftp->ftp_passok = FTPXY_USER_1;
			ftp->ftp_incok = 1;
		}
	} else if (!strncmp(cmd, "AUTH ", 5)) {
		ftp->ftp_passok = FTPXY_AUTH_1;
		ftp->ftp_incok = 1;
	} else if (!strncmp(cmd, "PASS ", 5)) {
		if (ftp->ftp_passok == FTPXY_USOK_1) {
			ftp->ftp_passok = FTPXY_PASS_1;
			ftp->ftp_incok = 1;
		} else if (ftp->ftp_passok == FTPXY_USOK_2) {
			ftp->ftp_passok = FTPXY_PASS_2;
			ftp->ftp_incok = 1;
		}
	} else if ((ftp->ftp_passok == FTPXY_AUOK_1) &&
		   !strncmp(cmd, "ADAT ", 5)) {
		ftp->ftp_passok = FTPXY_ADAT_1;
		ftp->ftp_incok = 1;
	} else if ((ftp->ftp_passok == FTPXY_PAOK_1 ||
		    ftp->ftp_passok == FTPXY_PAOK_2) &&
		 !strncmp(cmd, "ACCT ", 5)) {
		ftp->ftp_passok = FTPXY_ACCT_1;
		ftp->ftp_incok = 1;
	} else if ((ftp->ftp_passok == FTPXY_GO) && !ippr_ftp_pasvonly &&
		 !strncmp(cmd, "PORT ", 5)) {
		inc = ippr_ftp_port(fin, ip, nat, f, dlen);
	} else if (ippr_ftp_insecure && !ippr_ftp_pasvonly &&
		   !strncmp(cmd, "PORT ", 5)) {
		inc = ippr_ftp_port(fin, ip, nat, f, dlen);
	}

	while ((*rptr++ != '\n') && (rptr < wptr))
		;
	f->ftps_rptr = rptr;
	return inc;
}


int ippr_ftp_pasv(fin, ip, nat, ftp, dlen)
fr_info_t *fin;
ip_t *ip;
nat_t *nat;
ftpinfo_t *ftp;
int dlen;
{
	tcphdr_t *tcp, tcph, *tcp2 = &tcph;
	struct in_addr swip, swip2;
	u_int a1, a2, a3, a4;
	u_short a5, a6, dp;
	fr_info_t fi;
	ftpside_t *f;
	nat_t *ipn;
	int inc;
	char *s;

	if (ippr_ftp_forcepasv != 0 &&
	    ftp->ftp_side[0].ftps_cmds != FTPXY_C_PASV) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout,
			"ippr_ftp_pasv:ftps_cmds(%d) != FTPXY_C_PASV\n",
			ftp->ftp_side[0].ftps_cmds);
#endif
		return 0;
	}

	f = &ftp->ftp_side[1];

#define	PASV_REPLEN	24
	/*
	 * Check for PASV reply message.
	 */
	if (dlen < IPF_MIN227LEN) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout,
			"ippr_ftp_pasv:dlen(%d) < IPF_MIN227LEN\n", dlen);
#endif
		return 0;
	} else if (strncmp(f->ftps_rptr,
			   "227 Entering Passive Mod", PASV_REPLEN)) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_pasv:227 reply wrong\n");
#endif
		return 0;
	}

	tcp = (tcphdr_t *)fin->fin_dp;

	/*
	 * Skip the PASV reply + space
	 */
	s = f->ftps_rptr + PASV_REPLEN;
	while (*s && !isdigit(*s))
		s++;
	/*
	 * Pick out the address components, two at a time.
	 */
	a1 = ippr_ftp_atoi(&s);
	if (s == NULL) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_pasv:ippr_ftp_atoi(1) failed\n");
#endif
		return 0;
	}
	a2 = ippr_ftp_atoi(&s);
	if (s == NULL) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_pasv:ippr_ftp_atoi(2) failed\n");
#endif
		return 0;
	}

	/*
	 * check that IP address in the PORT/PASV reply is the same as the
	 * sender of the command - prevents using PORT for port scanning.
	 */
	a1 <<= 16;
	a1 |= a2;
	if (a1 != ntohl(nat->nat_oip.s_addr)) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_pasv:a1 != nat->nat_oip\n");
#endif
		return 0;
	}

	a5 = ippr_ftp_atoi(&s);
	if (s == NULL) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_pasv:ippr_ftp_atoi(3) failed\n");
#endif
		return 0;
	}

	if (*s == ')')
		s++;
	if (*s == '.')
		s++;
	if (*s == '\n')
		s--;
	/*
	 * check for CR-LF at the end.
	 */
	if ((*s == '\r') && (*(s + 1) == '\n')) {
		s += 2;
		a6 = a5 & 0xff;
	} else {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_pasv:missing cr-lf\n");
#endif
		return 0;
	}
	a5 >>= 8;
	/*
	 * Calculate new address parts for 227 reply
	 */
	a1 = ntohl(ip->ip_src.s_addr);
	a2 = (a1 >> 16) & 0xff;
	a3 = (a1 >> 8) & 0xff;
	a4 = a1 & 0xff;
	a1 >>= 24;
	inc = 0;
#if 0
	olen = s - f->ftps_rptr;
	(void) sprintf(newbuf, "%s %u,%u,%u,%u,%u,%u\r\n",
		       "227 Entering Passive Mode", a1, a2, a3, a4, a5, a6);
	nlen = strlen(newbuf);
	inc = nlen - olen;
	if ((inc + ip->ip_len) > 65535)
		return 0;

#if !defined(_KERNEL)
	m = *fin->fin_mp;
	m_copyback(m, off, nlen, newbuf);
#else
# if SOLARIS
	m = fin->fin_qfm;
	for (m1 = m; m1->b_cont; m1 = m1->b_cont)
		;
	if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) {
		mblk_t *nm;

		/* alloc enough to keep same trailer space for lower driver */
		nm = allocb(nlen, BPRI_MED);
		PANIC((!nm),("ippr_ftp_out: allocb failed"));

		nm->b_band = m1->b_band;
		nm->b_wptr += nlen;

		m1->b_wptr -= olen;
		PANIC((m1->b_wptr < m1->b_rptr),
		      ("ippr_ftp_out: cannot handle fragmented data block"));

		linkb(m1, nm);
	} else {
		m1->b_wptr += inc;
	}
	/*copyin_mblk(m, off, nlen, newbuf);*/
# else /* SOLARIS */
	m = *fin->fin_mp;
	if (inc < 0)
		m_adj(m, inc);
	/* the mbuf chain will be extended if necessary by m_copyback() */
	/*m_copyback(m, off, nlen, newbuf);*/
# endif /* SOLARIS */
#endif /* _KERNEL */
	if (inc != 0) {
#if ((SOLARIS || defined(__sgi)) && defined(_KERNEL)) || !defined(_KERNEL)
		register u_32_t	sum1, sum2;

		sum1 = ip->ip_len;
		sum2 = ip->ip_len + inc;

		/* Because ~1 == -2, We really need ~1 == -1 */
		if (sum1 > sum2)
			sum2--;
		sum2 -= sum1;
		sum2 = (sum2 & 0xffff) + (sum2 >> 16);

		fix_outcksum(fin, &ip->ip_sum, sum2);
#endif /* SOLARIS || defined(__sgi) */
		ip->ip_len += inc;
	}
#endif /* 0 */

	/*
	 * Add skeleton NAT entry for connection which will come back the
	 * other way.
	 */
	bcopy((char *)fin, (char *)&fi, sizeof(fi));
	fi.fin_data[0] = 0;
	dp = htons(fin->fin_data[1] - 1);
	fi.fin_data[1] = ntohs(dp);
	ipn = nat_outlookup(&fi, IPN_TCP, nat->nat_p, nat->nat_inip,
			    ip->ip_dst, 0);
	if (ipn == NULL) {
		int slen;

		slen = ip->ip_len;
		ip->ip_len = fin->fin_hlen + sizeof(*tcp2);
		bzero((char *)tcp2, sizeof(*tcp2));
		tcp2->th_win = htons(8192);
		tcp2->th_sport = 0;		/* XXX - fake it for nat_new */
		tcp2->th_off = 5;
		tcp2->th_flags = TH_SYN;
		fi.fin_data[1] = a5 << 8 | a6;
		fi.fin_dlen = sizeof(*tcp2);
		tcp2->th_dport = htons(fi.fin_data[1]);
		fi.fin_data[0] = 0;
		fi.fin_dp = (char *)tcp2;
		fi.fin_fr = &ftppxyfr;
		fi.fin_out = 1;
		swip = ip->ip_src;
		swip2 = ip->ip_dst;
		fi.fin_fi.fi_daddr = ip->ip_src.s_addr;
		fi.fin_fi.fi_saddr = nat->nat_inip.s_addr;
		ip->ip_dst = ip->ip_src;
		ip->ip_src = nat->nat_inip;
		ipn = nat_new(&fi, ip, nat->nat_ptr, NULL, IPN_TCP|FI_W_SPORT,
			      NAT_OUTBOUND);
		if (ipn != NULL) {
			ipn->nat_age = fr_defnatage;
			(void) fr_addstate(ip, &fi, NULL,
					   FI_W_SPORT|FI_IGNOREPKT);
		}
		ip->ip_len = slen;
		ip->ip_src = swip;
		ip->ip_dst = swip2;
	}
	return inc;
}


int ippr_ftp_server(fin, ip, nat, ftp, dlen)
fr_info_t *fin;
ip_t *ip;
nat_t *nat;
ftpinfo_t *ftp;
int dlen;
{
	char *rptr, *wptr;
	ftpside_t *f;
	int inc;

	inc = 0;
	f = &ftp->ftp_side[1];
	rptr = f->ftps_rptr;
	wptr = f->ftps_wptr;

	if (!isdigit(*rptr) || !isdigit(*(rptr + 1)) || !isdigit(*(rptr + 2)))
		return 0;
	if (ftp->ftp_passok == FTPXY_GO) {
		if (!strncmp(rptr, "227 ", 4))
			inc = ippr_ftp_pasv(fin, ip, nat, ftp, dlen);
	} else if (ippr_ftp_insecure && !strncmp(rptr, "227 ", 4)) {
		inc = ippr_ftp_pasv(fin, ip, nat, ftp, dlen);
	} else if (*rptr == '5' || *rptr == '4')
		ftp->ftp_passok = FTPXY_INIT;
	else if (ftp->ftp_incok) {
		if (*rptr == '3') {
			if (ftp->ftp_passok == FTPXY_ACCT_1)
				ftp->ftp_passok = FTPXY_GO;
			else
				ftp->ftp_passok++;
		} else if (*rptr == '2') {
			switch (ftp->ftp_passok)
			{
			case FTPXY_USER_1 :
			case FTPXY_USER_2 :
			case FTPXY_PASS_1 :
			case FTPXY_PASS_2 :
			case FTPXY_ACCT_1 :
				ftp->ftp_passok = FTPXY_GO;
				break;
			default :
				ftp->ftp_passok += 3;
				break;
			}
		}
	}
	ftp->ftp_incok = 0;

	while ((*rptr++ != '\n') && (rptr < wptr))
		;
	f->ftps_rptr = rptr;
	return inc;
}


/*
 * Look to see if the buffer starts with something which we recognise as
 * being the correct syntax for the FTP protocol.
 */
int ippr_ftp_client_valid(ftps, buf, len)
ftpside_t *ftps;
char *buf;
size_t len;
{
	register char *s, c;
	register size_t i = len;
	char cmd[5];

	if (i < 5) {
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout, "ippr_ftp_client_valid:i(%lu) < 5\n",
			(u_long)i);
#endif
		return 2;
	}
	s = buf;
	c = *s++;
	i--;

	if (isalpha(c)) {
		cmd[0] = toupper(c);
		c = *s++;
		i--;
		if (isalpha(c)) {
			cmd[1] = toupper(c);
			c = *s++;
			i--;
			if (isalpha(c)) {
				cmd[2] = toupper(c);
				c = *s++;
				i--;
				if (isalpha(c)) {
					cmd[3] = toupper(c);
					c = *s++;
					i--;
					if ((c != ' ') && (c != '\r'))
						goto bad_client_command;
				} else if ((c != ' ') && (c != '\r'))
					goto bad_client_command;
			} else
				goto bad_client_command;
		} else
			goto bad_client_command;
	} else {
bad_client_command:
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout,
			"ippr_ftp_client_valid:bad cmd:len %lu i %lu c 0x%x\n",
			(u_long)i, (u_long)len, c);
#endif
		return 1;
	}

	for (; i; i--) {
		c = *s++;
		if (c == '\n') {
			cmd[4] = '\0';
			if (!strcmp(cmd, "PASV"))
				ftps->ftps_cmds = FTPXY_C_PASV;
			else
				ftps->ftps_cmds = 0;
			return 0;
		}
	}
#if !defined(_KERNEL) && !defined(KERNEL)
	fprintf(stdout, "ippr_ftp_client_valid:junk after cmd[%s]\n", buf);
#endif
	return 2;
}


int ippr_ftp_server_valid(ftps, buf, len)
ftpside_t *ftps;
char *buf;
size_t len;
{
	register char *s, c;
	register size_t i = len;
	int cmd;

	if (i < 5)
		return 2;
	s = buf;
	c = *s++;
	cmd = 0;
	i--;

	if (isdigit(c)) {
		cmd = (c - '0') * 100;
		c = *s++;
		i--;
		if (isdigit(c)) {
			cmd += (c - '0') * 10;
			c = *s++;
			i--;
			if (isdigit(c)) {
				cmd += (c - '0');
				c = *s++;
				i--;
				if ((c != '-') && (c != ' '))
					goto bad_server_command;
			} else
				goto bad_server_command;
		} else
			goto bad_server_command;
	} else {
bad_server_command:
#if !defined(_KERNEL) && !defined(KERNEL)
		fprintf(stdout,
			"ippr_ftp_server_valid:bad cmd:len %lu i %lu c 0x%x\n",
			(u_long)i, (u_long)len, c);
#endif
		return 1;
	}

	for (; i; i--) {
		c = *s++;
		if (c == '\n') {
			ftps->ftps_cmds = cmd;
			return 0;
		}
	}
#if !defined(_KERNEL) && !defined(KERNEL)
	fprintf(stdout, "ippr_ftp_server_valid:junk after cmd[%s]\n", buf);
#endif
	return 2;
}


int ippr_ftp_valid(ftp, side, buf, len)
ftpinfo_t *ftp;
int side;
char *buf;
size_t len;
{
	ftpside_t *ftps;
	int ret;

	ftps = &ftp->ftp_side[side];

	if (side == 0)
		ret = ippr_ftp_client_valid(ftps, buf, len);
	else
		ret = ippr_ftp_server_valid(ftps, buf, len);
	return ret;
}


/*
 * rv == 0 for outbound processing,
 * rv == 1 for inbound processing.
 */
int ippr_ftp_process(fin, ip, nat, ftp, rv)
fr_info_t *fin;
ip_t *ip;
nat_t *nat;
ftpinfo_t *ftp;
int rv;
{
	int mlen, len, off, inc, i, sel, sel2, ok, ackoff, seqoff;
	u_32_t thseq, thack;
	char *rptr, *wptr;
	ap_session_t *aps;
	ftpside_t *f, *t;
	tcphdr_t *tcp;
	mb_t *m;

	tcp = (tcphdr_t *)fin->fin_dp;
	off = fin->fin_hlen + (tcp->th_off << 2);
#if	SOLARIS && defined(_KERNEL)
	m = fin->fin_qfm;
#else
	m = *fin->fin_mp;
#endif

#ifndef	_KERNEL
	mlen = mbuflen(m);
#else
# if	SOLARIS
	mlen = msgdsize(m);
# else
	mlen = mbufchainlen(m);
# endif
#endif
	mlen -= off;

	aps = nat->nat_aps;
	t = &ftp->ftp_side[1 - rv];
	f = &ftp->ftp_side[rv];
	thseq = ntohl(tcp->th_seq);
	thack = ntohl(tcp->th_ack);

	sel = aps->aps_sel[1 - rv];
	sel2 = aps->aps_sel[rv];
	if (rv == 0) {
		seqoff = aps->aps_seqoff[sel];
		if (aps->aps_seqmin[sel] > seqoff + thseq)
			seqoff = aps->aps_seqoff[!sel];
		ackoff = aps->aps_ackoff[sel2];
		if (aps->aps_ackmin[sel2] > ackoff + thack)
			ackoff = aps->aps_ackoff[!sel2];
	} else {
#if PROXY_DEBUG
		printf("seqoff %d thseq %x ackmin %x\n", seqoff, thseq,
			aps->aps_ackmin[sel]);
#endif
		seqoff = aps->aps_ackoff[sel];
		if (aps->aps_ackmin[sel] > seqoff + thseq)
			seqoff = aps->aps_ackoff[!sel];

#if PROXY_DEBUG
		printf("ackoff %d thack %x seqmin %x\n", ackoff, thack,
			aps->aps_seqmin[sel2]);
#endif
		ackoff = aps->aps_seqoff[sel2];
		if (ackoff > 0) {
			if (aps->aps_seqmin[sel2] > ackoff + thack)
				ackoff = aps->aps_seqoff[!sel2];
		} else {
			if (aps->aps_seqmin[sel2] > thack)
				ackoff = aps->aps_seqoff[!sel2];
		}
	}
#if PROXY_DEBUG
	printf("%s: %x seq %x/%d ack %x/%d len %d\n", rv ? "IN" : "OUT",
		tcp->th_flags, thseq, seqoff, thack, ackoff, mlen);
	printf("sel %d seqmin %x/%x offset %d/%d\n", sel,
		aps->aps_seqmin[sel], aps->aps_seqmin[sel2],
		aps->aps_seqoff[sel], aps->aps_seqoff[sel2]);
	printf("sel %d ackmin %x/%x offset %d/%d\n", sel2,
		aps->aps_ackmin[sel], aps->aps_ackmin[sel2],
		aps->aps_ackoff[sel], aps->aps_ackoff[sel2]);
#endif

	/*
	 * XXX - Ideally, this packet should get dropped because we now know
	 * that it is out of order (and there is no real danger in doing so
	 * apart from causing packets to go through here ordered).
	 */
#if PROXY_DEBUG
	printf("rv %d t:seq[0] %x seq[1] %x %d/%d\n",
		rv, t->ftps_seq[0], t->ftps_seq[1], seqoff, ackoff);
#endif

	ok = 0;
	if (t->ftps_seq[0] == 0) {
		t->ftps_seq[0] = thack;
		ok = 1;
	} else {
		if (ackoff == 0) {
			if (t->ftps_seq[0] == thack)
				ok = 1;
			else if (t->ftps_seq[1] == thack) {
				t->ftps_seq[0] = thack;
				ok = 1;
			}
		} else {
			if (t->ftps_seq[0] + ackoff == thack)
				ok = 1;
			else if (t->ftps_seq[0] == thack + ackoff)
				ok = 1;
			else if (t->ftps_seq[1] + ackoff == thack) {
				t->ftps_seq[0] = thack - ackoff;
				ok = 1;
			} else if (t->ftps_seq[1] == thack + ackoff) {
				t->ftps_seq[0] = thack - ackoff;
				ok = 1;
			}
		}
	}

#if PROXY_DEBUG
	if (!ok)
		printf("not  ok\n");
#endif

	if (!mlen) {
		if (t->ftps_seq[0] + ackoff != thack) {
#if !defined(_KERNEL) && !defined(KERNEL)
			fprintf(stdout,
		"ippr_ftp_process:seq[0](%x) + ackoff(%x) != thack(%x)\n",
				t->ftps_seq[0], ackoff, thack);
#endif
			return APR_ERR(1);
		}

#if PROXY_DEBUG
	printf("f:seq[0] %x seq[1] %x\n", f->ftps_seq[0], f->ftps_seq[1]);
#endif
		if (tcp->th_flags & TH_FIN) {
			if (thseq == f->ftps_seq[1]) {
				f->ftps_seq[0] = f->ftps_seq[1] - seqoff;
				f->ftps_seq[1] = thseq + 1 - seqoff;
			} else {
#if PROXY_DEBUG || (!defined(_KERNEL) && !defined(KERNEL))
				printf("FIN: thseq %x seqoff %d ftps_seq %x\n",
					thseq, seqoff, f->ftps_seq[0]);
#endif
				return APR_ERR(1);
			}
		}
		f->ftps_len = 0;
		return 0;
	}

	ok = 0;
	if ((thseq == f->ftps_seq[0]) || (thseq == f->ftps_seq[1])) {
		ok = 1;
	/*
	 * Retransmitted data packet.
	 */
	} else if ((thseq + mlen == f->ftps_seq[0]) ||
		   (thseq + mlen == f->ftps_seq[1])) {
		ok = 1;
	}

	if (ok == 0) {
		inc = thseq - f->ftps_seq[0];
#if PROXY_DEBUG || (!defined(_KERNEL) && !defined(KERNEL))
		printf("inc %d sel %d rv %d\n", inc, sel, rv);
		printf("th_seq %x ftps_seq %x/%x\n", thseq, f->ftps_seq[0],
			f->ftps_seq[1]);
		printf("ackmin %x ackoff %d\n", (u_int)aps->aps_ackmin[sel],
			aps->aps_ackoff[sel]);
		printf("seqmin %x seqoff %d\n", (u_int)aps->aps_seqmin[sel],
			aps->aps_seqoff[sel]);
#endif

		return APR_ERR(1);
	}

	inc = 0;
	rptr = f->ftps_rptr;
	wptr = f->ftps_wptr;
	f->ftps_seq[0] = thseq;
	f->ftps_seq[1] = f->ftps_seq[0] + mlen;
	f->ftps_len = mlen;

	while (mlen > 0) {
		len = MIN(mlen, FTP_BUFSZ / 2);

#if !defined(_KERNEL)
		bcopy((char *)m + off, wptr, len);
#else
# if SOLARIS
		copyout_mblk(m, off, len, wptr);
# else
		m_copydata(m, off, len, wptr);
# endif
#endif
		mlen -= len;
		off += len;
		wptr += len;
		f->ftps_wptr = wptr;
		if (f->ftps_junk == 2)
			f->ftps_junk = ippr_ftp_valid(ftp, rv, rptr,
						      wptr - rptr);

		while ((f->ftps_junk == 0) && (wptr > rptr)) {
			f->ftps_junk = ippr_ftp_valid(ftp, rv, rptr,
						      wptr - rptr);
			if (f->ftps_junk == 0) {
				f->ftps_cmds++;
				len = wptr - rptr;
				f->ftps_rptr = rptr;
				if (rv)
					inc += ippr_ftp_server(fin, ip, nat,
							       ftp, len);
				else
					inc += ippr_ftp_client(fin, ip, nat,
							       ftp, len);
				rptr = f->ftps_rptr;
				wptr = f->ftps_wptr;
			}
		}

		/*
		 * Off to a bad start so lets just forget about using the
		 * ftp proxy for this connection.
		 */
		if ((f->ftps_cmds == 0) && (f->ftps_junk == 1)) {
			/* f->ftps_seq[1] += inc; */
#if !defined(_KERNEL) && !defined(KERNEL)
			fprintf(stdout,
				"ippr_ftp_process:cmds == 0 junk == 1\n");
#endif
			return APR_ERR(2);
		}

		while ((f->ftps_junk == 1) && (rptr < wptr)) {
			while ((rptr < wptr) && (*rptr != '\r'))
				rptr++;

			if (*rptr == '\r') {
				if (rptr + 1 < wptr) {
					if (*(rptr + 1) == '\n') {
						rptr += 2;
						f->ftps_junk = 0;
					} else
						rptr++;
				} else
					break;
			}
		}
		f->ftps_rptr = rptr;

		if (rptr == wptr) {
			rptr = wptr = f->ftps_buf;
		} else {
			if ((wptr > f->ftps_buf + FTP_BUFSZ / 2)) {
				i = wptr - rptr;
				if ((rptr == f->ftps_buf) ||
				    (wptr - rptr > FTP_BUFSZ / 2)) {
					f->ftps_junk = 1;
					rptr = wptr = f->ftps_buf;
				} else {
					bcopy(rptr, f->ftps_buf, i);
					wptr = f->ftps_buf + i;
					rptr = f->ftps_buf;
				}
			}
			f->ftps_rptr = rptr;
			f->ftps_wptr = wptr;
		}
	}

	/* f->ftps_seq[1] += inc; */
	if (tcp->th_flags & TH_FIN)
		f->ftps_seq[1]++;
#if PROXY_DEBUG
# ifndef	_KERNEL
	mlen = mbuflen(m);
# else
#  if	SOLARIS
	mlen = msgdsize(m);
#  else
	mlen = mbufchainlen(m);
#  endif
# endif
	mlen -= off;
	printf("ftps_seq[1] = %x inc %d len %d\n", f->ftps_seq[1], inc, mlen);
#endif

	f->ftps_rptr = rptr;
	f->ftps_wptr = wptr;
	return APR_INC(inc);
}


int ippr_ftp_out(fin, ip, aps, nat)
fr_info_t *fin;
ip_t *ip;
ap_session_t *aps;
nat_t *nat;
{
	ftpinfo_t *ftp;

	ftp = aps->aps_data;
	if (ftp == NULL)
		return 0;
	return ippr_ftp_process(fin, ip, nat, ftp, 0);
}


int ippr_ftp_in(fin, ip, aps, nat)
fr_info_t *fin;
ip_t *ip;
ap_session_t *aps;
nat_t *nat;
{
	ftpinfo_t *ftp;

	ftp = aps->aps_data;
	if (ftp == NULL)
		return 0;
	return ippr_ftp_process(fin, ip, nat, ftp, 1);
}


/*
 * ippr_ftp_atoi - implement a version of atoi which processes numbers in
 * pairs separated by commas (which are expected to be in the range 0 - 255),
 * returning a 16 bit number combining either side of the , as the MSB and
 * LSB.
 */
u_short ippr_ftp_atoi(ptr)
char **ptr;
{
	register char *s = *ptr, c;
	register u_char i = 0, j = 0;

	while ((c = *s++) && isdigit(c)) {
		i *= 10;
		i += c - '0';
	}
	if (c != ',') {
		*ptr = NULL;
		return 0;
	}
	while ((c = *s++) && isdigit(c)) {
		j *= 10;
		j += c - '0';
	}
	*ptr = s;
	i &= 0xff;
	j &= 0xff;
	return (i << 8) | j;
}