/*
 * Copyright (C) 2002-2003 by Darren Reed
 *
 * Simple PPTP transparent proxy for in-kernel use.  For use with the NAT
 * code.
 *
 * $Id: ip_pptp_pxy.c,v 2.10.2.10 2005/07/15 21:56:52 darrenr Exp $
 *
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#define IPF_PPTP_PROXY

typedef struct ifs_pptppxy {
        frentry_t       pptpfr;
        int             pptp_proxy_init;
} ifs_pptppxy_t;

typedef struct pptp_hdr {
        u_short pptph_len;
        u_short pptph_type;
        u_32_t  pptph_cookie;
} pptp_hdr_t;

#define PPTP_MSGTYPE_CTL        1
#define PPTP_MTCTL_STARTREQ     1
#define PPTP_MTCTL_STARTREP     2
#define PPTP_MTCTL_STOPREQ      3
#define PPTP_MTCTL_STOPREP      4
#define PPTP_MTCTL_ECHOREQ      5
#define PPTP_MTCTL_ECHOREP      6
#define PPTP_MTCTL_OUTREQ       7
#define PPTP_MTCTL_OUTREP       8
#define PPTP_MTCTL_INREQ        9
#define PPTP_MTCTL_INREP        10
#define PPTP_MTCTL_INCONNECT    11
#define PPTP_MTCTL_CLEAR        12
#define PPTP_MTCTL_DISCONNECT   13
#define PPTP_MTCTL_WANERROR     14
#define PPTP_MTCTL_LINKINFO     15


int ippr_pptp_init __P((void **, ipf_stack_t *));
void ippr_pptp_fini __P((void **, ipf_stack_t *));
int ippr_pptp_new __P((fr_info_t *, ap_session_t *, nat_t *, void *));
void ippr_pptp_del __P((ap_session_t *, void *, ipf_stack_t *));
int ippr_pptp_inout __P((fr_info_t *, ap_session_t *, nat_t *, void *));
void ippr_pptp_donatstate __P((fr_info_t *, nat_t *, pptp_pxy_t *, ifs_pptppxy_t *));
int ippr_pptp_message __P((fr_info_t *, nat_t *, pptp_pxy_t *, pptp_side_t *, ifs_pptppxy_t *));
int ippr_pptp_nextmessage __P((fr_info_t *, nat_t *, pptp_pxy_t *, int, ifs_pptppxy_t *));
int ippr_pptp_mctl __P((fr_info_t *, nat_t *, pptp_pxy_t *, pptp_side_t *, ifs_pptppxy_t *));

int     ippr_pptp_debug = 0;                    /* It never changes */
int     ippr_pptp_gretimeout = IPF_TTLVAL(120); /* 2 minutes, never changes */

/*
 * PPTP application proxy initialization.
 */
/*ARGSUSED*/
int ippr_pptp_init(private, ifs)
void **private;
ipf_stack_t *ifs;
{
        ifs_pptppxy_t *ifspptp;

        KMALLOC(ifspptp, ifs_pptppxy_t *);
        if (ifspptp == NULL)
                return -1;

        bzero((char *)&ifspptp->pptpfr, sizeof(ifspptp->pptpfr));
        ifspptp->pptpfr.fr_ref = 1;
        ifspptp->pptpfr.fr_age[0] = ippr_pptp_gretimeout;
        ifspptp->pptpfr.fr_age[1] = ippr_pptp_gretimeout;
        ifspptp->pptpfr.fr_flags = FR_OUTQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
        MUTEX_INIT(&ifspptp->pptpfr.fr_lock, "PPTP proxy rule lock");
        ifspptp->pptp_proxy_init = 1;

        *private = (void *)ifspptp;

        return 0;
}


/*ARGSUSED*/
void ippr_pptp_fini(private, ifs)
void **private;
ipf_stack_t *ifs;
{
        ifs_pptppxy_t *ifspptp = *((ifs_pptppxy_t **)private);

        if (ifspptp->pptp_proxy_init == 1) {
                MUTEX_DESTROY(&ifspptp->pptpfr.fr_lock);
                ifspptp->pptp_proxy_init = 0;
        }

        KFREE(ifspptp);
        *private = NULL;
}


/*
 * Setup for a new PPTP proxy.
 */
/*ARGSUSED*/
int ippr_pptp_new(fin, aps, nat, private)
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
void *private;
{
        pptp_pxy_t *pptp;
        ipnat_t *ipn;
        ip_t *ip;

        ip = fin->fin_ip;

        if (nat_outlookup(fin, 0, IPPROTO_GRE, nat->nat_inip,
                          ip->ip_dst) != NULL) {
                if (ippr_pptp_debug > 0)
                        printf("ippr_pptp_new: GRE session already exists\n");
                return -1;
        }

        aps->aps_psiz = sizeof(*pptp);
        KMALLOCS(aps->aps_data, pptp_pxy_t *, sizeof(*pptp));
        if (aps->aps_data == NULL) {
                if (ippr_pptp_debug > 0)
                        printf("ippr_pptp_new: malloc for aps_data failed\n");
                return -1;
        }

        /*
         * Create NAT rule against which the tunnel/transport mapping is
         * created.  This is required because the current NAT rule does not
         * describe GRE but TCP instead.
         */
        pptp = aps->aps_data;
        bzero((char *)pptp, sizeof(*pptp));
        ipn = &pptp->pptp_rule;
        ipn->in_ifps[0] = fin->fin_ifp;
        ipn->in_apr = NULL;
        ipn->in_use = 1;
        ipn->in_hits = 1;
        ipn->in_ippip = 1;
        if (nat->nat_dir == NAT_OUTBOUND) {
                ipn->in_nip = ntohl(nat->nat_outip.s_addr);
                ipn->in_outip = fin->fin_saddr;
                ipn->in_redir = NAT_MAP;
        } else if (nat->nat_dir == NAT_INBOUND) {
                ipn->in_nip = 0;
                ipn->in_outip = nat->nat_outip.s_addr;
                ipn->in_redir = NAT_REDIRECT;
        }
        ipn->in_inip = nat->nat_inip.s_addr;
        ipn->in_inmsk = 0xffffffff;
        ipn->in_outmsk = 0xffffffff;
        ipn->in_srcip = fin->fin_saddr;
        ipn->in_srcmsk = 0xffffffff;
        bcopy(nat->nat_ptr->in_ifnames[0], ipn->in_ifnames[0],
              sizeof(ipn->in_ifnames[0]));
        ipn->in_p = IPPROTO_GRE;

        pptp->pptp_side[0].pptps_wptr = pptp->pptp_side[0].pptps_buffer;
        pptp->pptp_side[1].pptps_wptr = pptp->pptp_side[1].pptps_buffer;
        return 0;
}


void ippr_pptp_donatstate(fin, nat, pptp, ifspptp)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
ifs_pptppxy_t *ifspptp;
{
        fr_info_t fi;
        grehdr_t gre;
        nat_t *nat2;
        u_char p;
        ip_t *ip;
        ipf_stack_t *ifs = fin->fin_ifs;

        ip = fin->fin_ip;
        p = ip->ip_p;

        nat2 = pptp->pptp_nat;
        if ((nat2 == NULL) || (pptp->pptp_state == NULL)) {
                bcopy((char *)fin, (char *)&fi, sizeof(fi));
                bzero((char *)&gre, sizeof(gre));
                fi.fin_fi.fi_p = IPPROTO_GRE;
                fi.fin_fr = &ifspptp->pptpfr;
                if ((nat->nat_dir == NAT_OUTBOUND && fin->fin_out) ||
                    (nat->nat_dir == NAT_INBOUND && !fin->fin_out)) {
                        fi.fin_data[0] = pptp->pptp_call[0];
                        fi.fin_data[1] = pptp->pptp_call[1];
                } else {
                        fi.fin_data[0] = pptp->pptp_call[1];
                        fi.fin_data[1] = pptp->pptp_call[0];
                }
                ip = fin->fin_ip;
                ip->ip_p = IPPROTO_GRE;
                fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
                fi.fin_flx |= FI_IGNORE;
                fi.fin_dp = &gre;
                gre.gr_flags = htons(1 << 13);
                if (fin->fin_out && nat->nat_dir == NAT_INBOUND) {
                        fi.fin_fi.fi_saddr = fin->fin_fi.fi_daddr;
                        fi.fin_fi.fi_daddr = nat->nat_outip.s_addr;
                } else if (!fin->fin_out && nat->nat_dir == NAT_OUTBOUND) {
                        fi.fin_fi.fi_saddr = nat->nat_inip.s_addr;
                        fi.fin_fi.fi_daddr = fin->fin_fi.fi_saddr;
                }
        }

        /*
         * Update NAT timeout/create NAT if missing.
         */
        if (nat2 != NULL)
                fr_queueback(&nat2->nat_tqe, ifs);
        else {
                nat2 = nat_new(&fi, &pptp->pptp_rule, &pptp->pptp_nat,
                               NAT_SLAVE, nat->nat_dir);
                pptp->pptp_nat = nat2;
                if (nat2 != NULL) {
                        (void) nat_proto(&fi, nat2, 0);
                        nat_update(&fi, nat2, nat2->nat_ptr);
                }
        }

        READ_ENTER(&ifs->ifs_ipf_state);
        if (pptp->pptp_state != NULL) {
                fr_queueback(&pptp->pptp_state->is_sti, ifs);
                RWLOCK_EXIT(&ifs->ifs_ipf_state);
        } else {
                RWLOCK_EXIT(&ifs->ifs_ipf_state);
                if (nat->nat_dir == NAT_INBOUND)
                        fi.fin_fi.fi_daddr = nat2->nat_inip.s_addr;
                else
                        fi.fin_fi.fi_saddr = nat2->nat_inip.s_addr;
                fi.fin_ifp = NULL;
                pptp->pptp_state = fr_addstate(&fi, &pptp->pptp_state,
                                               0);
        }
        ip->ip_p = p;
        return;
}


/*
 * Try and build up the next PPTP message in the TCP stream and if we can
 * build it up completely (fits in our buffer) then pass it off to the message
 * parsing function.
 */
int ippr_pptp_nextmessage(fin, nat, pptp, rev, ifspptp)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
int rev;
ifs_pptppxy_t *ifspptp;
{
        static char *funcname = "ippr_pptp_nextmessage";
        pptp_side_t *pptps;
        u_32_t start, end;
        pptp_hdr_t *hdr;
        tcphdr_t *tcp;
        int dlen, off;
        u_short len;
        char *msg;

        tcp = fin->fin_dp;
        dlen = fin->fin_dlen - (TCP_OFF(tcp) << 2);
        start = ntohl(tcp->th_seq);
        pptps = &pptp->pptp_side[rev];
        off = (char *)tcp - (char *)fin->fin_ip + (TCP_OFF(tcp) << 2) +
              fin->fin_ipoff;

        if (dlen <= 0)
                return 0;
        /*
         * If the complete data packet is before what we expect to see
         * "next", just ignore it as the chances are we've already seen it.
         * The next if statement following this one really just causes packets
         * ahead of what we've seen to be dropped, implying that something in
         * the middle went missing and we want to see that first.
         */
        end = start + dlen;
        if (pptps->pptps_next > end && pptps->pptps_next > start)
                return 0;

        if (pptps->pptps_next != start) {
                if (ippr_pptp_debug > 5)
                        printf("%s: next (%x) != start (%x)\n", funcname,
                                pptps->pptps_next, start);
                return -1;
        }

        msg = (char *)fin->fin_dp + (TCP_OFF(tcp) << 2);

        while (dlen > 0) {
                off += pptps->pptps_bytes;
                if (pptps->pptps_gothdr == 0) {
                        /*
                         * PPTP has an 8 byte header that inclues the cookie.
                         * The start of every message should include one and
                         * it should match 1a2b3c4d.  Byte order is ignored,
                         * deliberately, when printing out the error.
                         */
                        len = MIN(8 - pptps->pptps_bytes, dlen);
                        COPYDATA(fin->fin_m, off, len, pptps->pptps_wptr);
                        pptps->pptps_bytes += len;
                        pptps->pptps_wptr += len;
                        hdr = (pptp_hdr_t *)pptps->pptps_buffer;
                        if (pptps->pptps_bytes == 8) {
                                pptps->pptps_next += 8;
                                if (ntohl(hdr->pptph_cookie) != 0x1a2b3c4d) {
                                        if (ippr_pptp_debug > 1)
                                                printf("%s: bad cookie (%x)\n",
                                                       funcname,
                                                       hdr->pptph_cookie);
                                        return -1;
                                }
                        }
                        dlen -= len;
                        msg += len;
                        off += len;

                        pptps->pptps_gothdr = 1;
                        len = ntohs(hdr->pptph_len);
                        pptps->pptps_len = len;
                        pptps->pptps_nexthdr += len;

                        /*
                         * If a message is too big for the buffer, just set
                         * the fields for the next message to come along.
                         * The messages defined in RFC 2637 will not exceed
                         * 512 bytes (in total length) so this is likely a
                         * bad data packet, anyway.
                         */
                        if (len > sizeof(pptps->pptps_buffer)) {
                                if (ippr_pptp_debug > 3)
                                        printf("%s: message too big (%d)\n",
                                               funcname, len);
                                pptps->pptps_next = pptps->pptps_nexthdr;
                                pptps->pptps_wptr = pptps->pptps_buffer;
                                pptps->pptps_gothdr = 0;
                                pptps->pptps_bytes = 0;
                                pptps->pptps_len = 0;
                                break;
                        }
                }

                len = MIN(pptps->pptps_len - pptps->pptps_bytes, dlen);
                COPYDATA(fin->fin_m, off, len, pptps->pptps_wptr);
                pptps->pptps_bytes += len;
                pptps->pptps_wptr += len;
                pptps->pptps_next += len;

                if (pptps->pptps_len > pptps->pptps_bytes)
                        break;

                (void) ippr_pptp_message(fin, nat, pptp, pptps, ifspptp);
                pptps->pptps_wptr = pptps->pptps_buffer;
                pptps->pptps_gothdr = 0;
                pptps->pptps_bytes = 0;
                pptps->pptps_len = 0;

                start += len;
                msg += len;
                dlen -= len;
        }

        return 0;
}


/*
 * handle a complete PPTP message
 */
int ippr_pptp_message(fin, nat, pptp, pptps, ifspptp)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
pptp_side_t *pptps;
ifs_pptppxy_t *ifspptp;
{
        pptp_hdr_t *hdr = (pptp_hdr_t *)pptps->pptps_buffer;

        switch (ntohs(hdr->pptph_type))
        {
        case PPTP_MSGTYPE_CTL :
                (void) ippr_pptp_mctl(fin, nat, pptp, pptps, ifspptp);
                break;

        default :
                break;
        }
        return 0;
}


/*
 * handle a complete PPTP control message
 */
int ippr_pptp_mctl(fin, nat, pptp, pptps, ifspptp)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
pptp_side_t *pptps;
ifs_pptppxy_t *ifspptp;
{
        u_short *buffer = (u_short *)(pptps->pptps_buffer);
        pptp_side_t *pptpo;

        if (pptps == &pptp->pptp_side[0])
                pptpo = &pptp->pptp_side[1];
        else
                pptpo = &pptp->pptp_side[0];

        /*
         * Breakout to handle all the various messages.  Most are just state
         * transition.
         */
        switch (ntohs(buffer[4]))
        {
        case PPTP_MTCTL_STARTREQ :
                pptps->pptps_state = PPTP_MTCTL_STARTREQ;
                break;
        case PPTP_MTCTL_STARTREP :
                if (pptpo->pptps_state == PPTP_MTCTL_STARTREQ)
                        pptps->pptps_state = PPTP_MTCTL_STARTREP;
                break;
        case PPTP_MTCTL_STOPREQ :
                pptps->pptps_state = PPTP_MTCTL_STOPREQ;
                break;
        case PPTP_MTCTL_STOPREP :
                if (pptpo->pptps_state == PPTP_MTCTL_STOPREQ)
                        pptps->pptps_state = PPTP_MTCTL_STOPREP;
                break;
        case PPTP_MTCTL_ECHOREQ :
                pptps->pptps_state = PPTP_MTCTL_ECHOREQ;
                break;
        case PPTP_MTCTL_ECHOREP :
                if (pptpo->pptps_state == PPTP_MTCTL_ECHOREQ)
                        pptps->pptps_state = PPTP_MTCTL_ECHOREP;
                break;
        case PPTP_MTCTL_OUTREQ :
                pptps->pptps_state = PPTP_MTCTL_OUTREQ;
                break;
        case PPTP_MTCTL_OUTREP :
                if (pptpo->pptps_state == PPTP_MTCTL_OUTREQ) {
                        pptps->pptps_state = PPTP_MTCTL_OUTREP;
                        pptp->pptp_call[0] = buffer[7];
                        pptp->pptp_call[1] = buffer[6];
                        ippr_pptp_donatstate(fin, nat, pptp, ifspptp);
                }
                break;
        case PPTP_MTCTL_INREQ :
                pptps->pptps_state = PPTP_MTCTL_INREQ;
                break;
        case PPTP_MTCTL_INREP :
                if (pptpo->pptps_state == PPTP_MTCTL_INREQ) {
                        pptps->pptps_state = PPTP_MTCTL_INREP;
                        pptp->pptp_call[0] = buffer[7];
                        pptp->pptp_call[1] = buffer[6];
                        ippr_pptp_donatstate(fin, nat, pptp, ifspptp);
                }
                break;
        case PPTP_MTCTL_INCONNECT :
                pptps->pptps_state = PPTP_MTCTL_INCONNECT;
                break;
        case PPTP_MTCTL_CLEAR :
                pptps->pptps_state = PPTP_MTCTL_CLEAR;
                break;
        case PPTP_MTCTL_DISCONNECT :
                pptps->pptps_state = PPTP_MTCTL_DISCONNECT;
                break;
        case PPTP_MTCTL_WANERROR :
                pptps->pptps_state = PPTP_MTCTL_WANERROR;
                break;
        case PPTP_MTCTL_LINKINFO :
                pptps->pptps_state = PPTP_MTCTL_LINKINFO;
                break;
        }

        return 0;
}


/*
 * For outgoing PPTP packets.  refresh timeouts for NAT & state entries, if
 * we can.  If they have disappeared, recreate them.
 */
int ippr_pptp_inout(fin, aps, nat, private)
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
void *private;
{
        pptp_pxy_t *pptp;
        tcphdr_t *tcp;
        int rev;

        if ((fin->fin_out == 1) && (nat->nat_dir == NAT_INBOUND))
                rev = 1;
        else if ((fin->fin_out == 0) && (nat->nat_dir == NAT_OUTBOUND))
                rev = 1;
        else
                rev = 0;

        tcp = (tcphdr_t *)fin->fin_dp;
        if ((tcp->th_flags & TH_OPENING) == TH_OPENING) {
                pptp = (pptp_pxy_t *)aps->aps_data;
                pptp->pptp_side[1 - rev].pptps_next = ntohl(tcp->th_ack);
                pptp->pptp_side[1 - rev].pptps_nexthdr = ntohl(tcp->th_ack);
                pptp->pptp_side[rev].pptps_next = ntohl(tcp->th_seq) + 1;
                pptp->pptp_side[rev].pptps_nexthdr = ntohl(tcp->th_seq) + 1;
        }
        return ippr_pptp_nextmessage(fin, nat, (pptp_pxy_t *)aps->aps_data,
                                     rev, (ifs_pptppxy_t *)private);
}


/*
 * clean up after ourselves.
 */
/*ARGSUSED*/
void ippr_pptp_del(aps, private, ifs)
ap_session_t *aps;
void *private;
ipf_stack_t *ifs;
{
        pptp_pxy_t *pptp;

        pptp = aps->aps_data;

        if (pptp != NULL) {
                /*
                 * Don't bother changing any of the NAT structure details,
                 * *_del() is on a callback from aps_free(), from nat_delete()
                 */

                READ_ENTER(&ifs->ifs_ipf_state);
                if (pptp->pptp_state != NULL) {
                        pptp->pptp_state->is_die = ifs->ifs_fr_ticks + 1;
                        pptp->pptp_state->is_me = NULL;
                        fr_queuefront(&pptp->pptp_state->is_sti);
                }
                RWLOCK_EXIT(&ifs->ifs_ipf_state);

                pptp->pptp_state = NULL;
                pptp->pptp_nat = NULL;

        }
}