/*
 * demand.c - Support routines for demand-dialling.
 *
 * Copyright (c) 1996-2002 Paul Mackerras. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. The name(s) of the authors of this software must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by Paul Mackerras
 *     <paulus@samba.org>".
 *
 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT && DEMAND_SUPPORT  /* don't build if not configured for use in lwipopts.h */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#ifdef PPP_FILTER
#include <pcap-bpf.h>
#endif

#include "netif/ppp/ppp_impl.h"

#include "netif/ppp/fsm.h"
#include "netif/ppp/ipcp.h"
#include "netif/ppp/lcp.h"

char *frame;
int framelen;
int framemax;
int escape_flag;
int flush_flag;
int fcs;

struct packet {
    int length;
    struct packet *next;
    unsigned char data[1];
};

struct packet *pend_q;
struct packet *pend_qtail;

static int active_packet (unsigned char *, int);

/*
 * demand_conf - configure the interface for doing dial-on-demand.
 */
void
demand_conf()
{
    int i;
    const struct protent *protp;

/*    framemax = lcp_allowoptions[0].mru;
    if (framemax < PPP_MRU) */
    framemax = PPP_MRU;
    framemax += PPP_HDRLEN + PPP_FCSLEN;
    frame = malloc(framemax);
    if (frame == NULL)
    novm("demand frame");
    framelen = 0;
    pend_q = NULL;
    escape_flag = 0;
    flush_flag = 0;
    fcs = PPP_INITFCS;

    netif_set_mtu(pcb, LWIP_MIN(lcp_allowoptions[0].mru, PPP_MRU));
    if (ppp_send_config(pcb, PPP_MRU, (u32_t) 0, 0, 0) < 0
    || ppp_recv_config(pcb, PPP_MRU, (u32_t) 0, 0, 0) < 0)
        fatal("Couldn't set up demand-dialled PPP interface: %m");

#ifdef PPP_FILTER
    set_filters(&pass_filter, &active_filter);
#endif

    /*
     * Call the demand_conf procedure for each protocol that's got one.
     */
    for (i = 0; (protp = protocols[i]) != NULL; ++i)
    if (protp->demand_conf != NULL)
        ((*protp->demand_conf)(pcb));
/* FIXME: find a way to die() here */
#if 0
        if (!((*protp->demand_conf)(pcb)))
        die(1);
#endif
}


/*
 * demand_block - set each network protocol to block further packets.
 */
void
demand_block()
{
    int i;
    const struct protent *protp;

    for (i = 0; (protp = protocols[i]) != NULL; ++i)
    if (protp->demand_conf != NULL)
        sifnpmode(pcb, protp->protocol & ~0x8000, NPMODE_QUEUE);
    get_loop_output();
}

/*
 * demand_discard - set each network protocol to discard packets
 * with an error.
 */
void
demand_discard()
{
    struct packet *pkt, *nextpkt;
    int i;
    const struct protent *protp;

    for (i = 0; (protp = protocols[i]) != NULL; ++i)
    if (protp->demand_conf != NULL)
        sifnpmode(pcb, protp->protocol & ~0x8000, NPMODE_ERROR);
    get_loop_output();

    /* discard all saved packets */
    for (pkt = pend_q; pkt != NULL; pkt = nextpkt) {
    nextpkt = pkt->next;
    free(pkt);
    }
    pend_q = NULL;
    framelen = 0;
    flush_flag = 0;
    escape_flag = 0;
    fcs = PPP_INITFCS;
}

/*
 * demand_unblock - set each enabled network protocol to pass packets.
 */
void
demand_unblock()
{
    int i;
    const struct protent *protp;

    for (i = 0; (protp = protocols[i]) != NULL; ++i)
    if (protp->demand_conf != NULL)
        sifnpmode(pcb, protp->protocol & ~0x8000, NPMODE_PASS);
}

/*
 * FCS lookup table as calculated by genfcstab.
 */
static u_short fcstab[256] = {
    0x0000,    0x1189,    0x2312,    0x329b,    0x4624,    0x57ad,    0x6536,    0x74bf,
    0x8c48,    0x9dc1,    0xaf5a,    0xbed3,    0xca6c,    0xdbe5,    0xe97e,    0xf8f7,
    0x1081,    0x0108,    0x3393,    0x221a,    0x56a5,    0x472c,    0x75b7,    0x643e,
    0x9cc9,    0x8d40,    0xbfdb,    0xae52,    0xdaed,    0xcb64,    0xf9ff,    0xe876,
    0x2102,    0x308b,    0x0210,    0x1399,    0x6726,    0x76af,    0x4434,    0x55bd,
    0xad4a,    0xbcc3,    0x8e58,    0x9fd1,    0xeb6e,    0xfae7,    0xc87c,    0xd9f5,
    0x3183,    0x200a,    0x1291,    0x0318,    0x77a7,    0x662e,    0x54b5,    0x453c,
    0xbdcb,    0xac42,    0x9ed9,    0x8f50,    0xfbef,    0xea66,    0xd8fd,    0xc974,
    0x4204,    0x538d,    0x6116,    0x709f,    0x0420,    0x15a9,    0x2732,    0x36bb,
    0xce4c,    0xdfc5,    0xed5e,    0xfcd7,    0x8868,    0x99e1,    0xab7a,    0xbaf3,
    0x5285,    0x430c,    0x7197,    0x601e,    0x14a1,    0x0528,    0x37b3,    0x263a,
    0xdecd,    0xcf44,    0xfddf,    0xec56,    0x98e9,    0x8960,    0xbbfb,    0xaa72,
    0x6306,    0x728f,    0x4014,    0x519d,    0x2522,    0x34ab,    0x0630,    0x17b9,
    0xef4e,    0xfec7,    0xcc5c,    0xddd5,    0xa96a,    0xb8e3,    0x8a78,    0x9bf1,
    0x7387,    0x620e,    0x5095,    0x411c,    0x35a3,    0x242a,    0x16b1,    0x0738,
    0xffcf,    0xee46,    0xdcdd,    0xcd54,    0xb9eb,    0xa862,    0x9af9,    0x8b70,
    0x8408,    0x9581,    0xa71a,    0xb693,    0xc22c,    0xd3a5,    0xe13e,    0xf0b7,
    0x0840,    0x19c9,    0x2b52,    0x3adb,    0x4e64,    0x5fed,    0x6d76,    0x7cff,
    0x9489,    0x8500,    0xb79b,    0xa612,    0xd2ad,    0xc324,    0xf1bf,    0xe036,
    0x18c1,    0x0948,    0x3bd3,    0x2a5a,    0x5ee5,    0x4f6c,    0x7df7,    0x6c7e,
    0xa50a,    0xb483,    0x8618,    0x9791,    0xe32e,    0xf2a7,    0xc03c,    0xd1b5,
    0x2942,    0x38cb,    0x0a50,    0x1bd9,    0x6f66,    0x7eef,    0x4c74,    0x5dfd,
    0xb58b,    0xa402,    0x9699,    0x8710,    0xf3af,    0xe226,    0xd0bd,    0xc134,
    0x39c3,    0x284a,    0x1ad1,    0x0b58,    0x7fe7,    0x6e6e,    0x5cf5,    0x4d7c,
    0xc60c,    0xd785,    0xe51e,    0xf497,    0x8028,    0x91a1,    0xa33a,    0xb2b3,
    0x4a44,    0x5bcd,    0x6956,    0x78df,    0x0c60,    0x1de9,    0x2f72,    0x3efb,
    0xd68d,    0xc704,    0xf59f,    0xe416,    0x90a9,    0x8120,    0xb3bb,    0xa232,
    0x5ac5,    0x4b4c,    0x79d7,    0x685e,    0x1ce1,    0x0d68,    0x3ff3,    0x2e7a,
    0xe70e,    0xf687,    0xc41c,    0xd595,    0xa12a,    0xb0a3,    0x8238,    0x93b1,
    0x6b46,    0x7acf,    0x4854,    0x59dd,    0x2d62,    0x3ceb,    0x0e70,    0x1ff9,
    0xf78f,    0xe606,    0xd49d,    0xc514,    0xb1ab,    0xa022,    0x92b9,    0x8330,
    0x7bc7,    0x6a4e,    0x58d5,    0x495c,    0x3de3,    0x2c6a,    0x1ef1,    0x0f78
};

/*
 * loop_chars - process characters received from the loopback.
 * Calls loop_frame when a complete frame has been accumulated.
 * Return value is 1 if we need to bring up the link, 0 otherwise.
 */
int
loop_chars(p, n)
    unsigned char *p;
    int n;
{
    int c, rv;

    rv = 0;

/* check for synchronous connection... */

    if ( (p[0] == 0xFF) && (p[1] == 0x03) ) {
        rv = loop_frame(p,n);
        return rv;
    }

    for (; n > 0; --n) {
    c = *p++;
    if (c == PPP_FLAG) {
        if (!escape_flag && !flush_flag
        && framelen > 2 && fcs == PPP_GOODFCS) {
        framelen -= 2;
        if (loop_frame((unsigned char *)frame, framelen))
            rv = 1;
        }
        framelen = 0;
        flush_flag = 0;
        escape_flag = 0;
        fcs = PPP_INITFCS;
        continue;
    }
    if (flush_flag)
        continue;
    if (escape_flag) {
        c ^= PPP_TRANS;
        escape_flag = 0;
    } else if (c == PPP_ESCAPE) {
        escape_flag = 1;
        continue;
    }
    if (framelen >= framemax) {
        flush_flag = 1;
        continue;
    }
    frame[framelen++] = c;
    fcs = PPP_FCS(fcs, c);
    }
    return rv;
}

/*
 * loop_frame - given a frame obtained from the loopback,
 * decide whether to bring up the link or not, and, if we want
 * to transmit this frame later, put it on the pending queue.
 * Return value is 1 if we need to bring up the link, 0 otherwise.
 * We assume that the kernel driver has already applied the
 * pass_filter, so we won't get packets it rejected.
 * We apply the active_filter to see if we want this packet to
 * bring up the link.
 */
int
loop_frame(frame, len)
    unsigned char *frame;
    int len;
{
    struct packet *pkt;

    /* dbglog("from loop: %P", frame, len); */
    if (len < PPP_HDRLEN)
    return 0;
    if ((PPP_PROTOCOL(frame) & 0x8000) != 0)
    return 0;        /* shouldn't get any of these anyway */
    if (!active_packet(frame, len))
    return 0;

    pkt = (struct packet *) malloc(sizeof(struct packet) + len);
    if (pkt != NULL) {
    pkt->length = len;
    pkt->next = NULL;
    memcpy(pkt->data, frame, len);
    if (pend_q == NULL)
        pend_q = pkt;
    else
        pend_qtail->next = pkt;
    pend_qtail = pkt;
    }
    return 1;
}

/*
 * demand_rexmit - Resend all those frames which we got via the
 * loopback, now that the real serial link is up.
 */
void
demand_rexmit(proto, newip)
    int proto;
    u32_t newip;
{
    struct packet *pkt, *prev, *nextpkt;
    unsigned short checksum;
    unsigned short pkt_checksum = 0;
    unsigned iphdr;
    struct timeval tv;
    char cv = 0;
    char ipstr[16];

    prev = NULL;
    pkt = pend_q;
    pend_q = NULL;
    tv.tv_sec = 1;
    tv.tv_usec = 0;
    select(0,NULL,NULL,NULL,&tv);    /* Sleep for 1 Seconds */
    for (; pkt != NULL; pkt = nextpkt) {
    nextpkt = pkt->next;
    if (PPP_PROTOCOL(pkt->data) == proto) {
            if ( (proto == PPP_IP) && newip ) {
        /* Get old checksum */

        iphdr = (pkt->data[4] & 15) << 2;
        checksum = *((unsigned short *) (pkt->data+14));
                if (checksum == 0xFFFF) {
                    checksum = 0;
                }

 
                if (pkt->data[13] == 17) {
                    pkt_checksum =  *((unsigned short *) (pkt->data+10+iphdr));
            if (pkt_checksum) {
                        cv = 1;
                        if (pkt_checksum == 0xFFFF) {
                            pkt_checksum = 0;
                        }
                    }
                    else {
                       cv = 0;
                    }
                }

        if (pkt->data[13] == 6) {
            pkt_checksum = *((unsigned short *) (pkt->data+20+iphdr));
            cv = 1;
                    if (pkt_checksum == 0xFFFF) {
                        pkt_checksum = 0;
                    }
        }

        /* Delete old Source-IP-Address */
                checksum -= *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
                checksum -= *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;

        pkt_checksum -= *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
        pkt_checksum -= *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;

        /* Change Source-IP-Address */
                * ((u32_t *) (pkt->data + 16)) = newip;

        /* Add new Source-IP-Address */
                checksum += *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
                checksum += *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;

                pkt_checksum += *((unsigned short *) (pkt->data+16)) ^ 0xFFFF;
                pkt_checksum += *((unsigned short *) (pkt->data+18)) ^ 0xFFFF;

        /* Write new checksum */
                if (!checksum) {
                    checksum = 0xFFFF;
                }
                *((unsigned short *) (pkt->data+14)) = checksum;
        if (pkt->data[13] == 6) {
            *((unsigned short *) (pkt->data+20+iphdr)) = pkt_checksum;
        }
        if (cv && (pkt->data[13] == 17) ) {
            *((unsigned short *) (pkt->data+10+iphdr)) = pkt_checksum;
        }

        /* Log Packet */
        strcpy(ipstr,inet_ntoa(*( (struct in_addr *) (pkt->data+16))));
        if (pkt->data[13] == 1) {
            syslog(LOG_INFO,"Open ICMP %s -> %s\n",
            ipstr,
            inet_ntoa(*( (struct in_addr *) (pkt->data+20))));
        } else {
            syslog(LOG_INFO,"Open %s %s:%d -> %s:%d\n",
            pkt->data[13] == 6 ? "TCP" : "UDP",
            ipstr,
            ntohs(*( (short *) (pkt->data+iphdr+4))),
            inet_ntoa(*( (struct in_addr *) (pkt->data+20))),
            ntohs(*( (short *) (pkt->data+iphdr+6))));
                }
            }
        output(pcb, pkt->data, pkt->length);
        free(pkt);
    } else {
        if (prev == NULL)
        pend_q = pkt;
        else
        prev->next = pkt;
        prev = pkt;
    }
    }
    pend_qtail = prev;
    if (prev != NULL)
    prev->next = NULL;
}

/*
 * Scan a packet to decide whether it is an "active" packet,
 * that is, whether it is worth bringing up the link for.
 */
static int
active_packet(p, len)
    unsigned char *p;
    int len;
{
    int proto, i;
    const struct protent *protp;

    if (len < PPP_HDRLEN)
    return 0;
    proto = PPP_PROTOCOL(p);
#ifdef PPP_FILTER
    p[0] = 1;        /* outbound packet indicator */
    if ((pass_filter.bf_len != 0
     && bpf_filter(pass_filter.bf_insns, p, len, len) == 0)
    || (active_filter.bf_len != 0
        && bpf_filter(active_filter.bf_insns, p, len, len) == 0)) {
    p[0] = 0xff;
    return 0;
    }
    p[0] = 0xff;
#endif
    for (i = 0; (protp = protocols[i]) != NULL; ++i) {
    if (protp->protocol < 0xC000 && (protp->protocol & ~0x8000) == proto) {
        if (protp->active_pkt == NULL)
        return 1;
        return (*protp->active_pkt)(p, len);
    }
    }
    return 0;            /* not a supported protocol !!?? */
}

#endif /* PPP_SUPPORT && DEMAND_SUPPORT */
