/*
 *  PPP.C   -- Send and receive datagrams on serial lines with
 *         Point-to-Point Protocol
 *
 *  This implementation of PPP is declared to be in the public domain.
 *
 *  Based (in part) upon previous implementations by:
 *  1989    -- Drew Daniel Perkins      (ddp@andrew.cmu.edu)
 *         Carnegie Mellon University
 *  09-90   -- Katie Stevens        (dkstevens@ucdavis.edu)
 *         UC Davis, Computing Services
 *
 *  Jan 91  Bill_Simpson@um.cc.umich.edu
 *      Computer Systems Consulting Services
 *
 *  Feb 91  Glenn McGregor          (ghm@merit.edu)
 *      Testing and suggestions.
 *
 *  May 91  Bill Simpson & Glenn McGregor
 *      Update to newest LCP and IPCP draft RFCs.
 *      Add quick installation features.
 *      Add support for echo and discard message sending.
 *
 *  Jul 91  Glenn McGregor & Bill Simpson
 *      Improve PAP user interface and fix related bugs.
 *      Remove pwaits and "phase machine".
 */
  
#include "global.h"
#ifdef PPP
#include "mbuf.h"
#include "proc.h"
#include "iface.h"
#include "internet.h"
#include "ip.h"
#include "slhc.h"
#ifdef LINUX
#include "lxasy.h"
#else
#include "i8250.h"
#endif
#include "asy.h"
#include "pktdrvr.h"
#include "socket.h"
#include "devparam.h"
#include "ppp.h"
#include "pppfsm.h"
#include "ppplcp.h"
#include "ppppap.h"
#include "pppipcp.h"
#include "trace.h"
  
/* Routines local to this file */
static struct mbuf *htonppp __ARGS((struct ppp_hdr *ppp, struct mbuf *data));
  
static void ppp_log __ARGS((struct ppp_s *ppp_p, char *comment));
static void ppp_error __ARGS((struct ppp_s *ppp_p, struct mbuf *bp, char *comment));
static void ppp_skipped __ARGS((struct ppp_s *ppp_p, struct mbuf *bp, char *comment));
  
static int ppp_raw __ARGS((struct iface *ifp, struct mbuf *data));
  
static void ppp_recv __ARGS((int dev, void *p1, void *p2));
  
static int ppp_iostatus __ARGS((struct iface *ifp, int command, int32 value));
static int ppp_discard  __ARGS((struct iface *ifp, struct mbuf *bp));
static int ppp_echo __ARGS((struct iface *ifp, struct mbuf *bp));
  
  
/*
 * FCS lookup table as generated by fcsgen.c
 */
int16 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
};
  
#define pppfcs(fcs, c)      ((fcs >> 8) ^ fcstab[(fcs ^ c) & 0x00ff])
#define SP_CHAR         0x20
  
  
/****************************************************************************/
  
/* Convert PPP header in host form to network form */
static struct mbuf *
htonppp(ppp, data)
struct ppp_hdr *ppp;
struct mbuf *data;
{
    struct mbuf *bp;
    register char *cp;
  
    /* Prepend header onto packet data */
    if ((bp = pushdown(data, PPP_HDR_LEN)) == NULLBUF) {
        free_p( data );
        return NULLBUF;
    }
  
    /* Load header with proper values */
    cp = bp->data;
    *cp++ = ppp->addr;
    *cp++ = ppp->control;
    cp = put16(cp,ppp->protocol);
  
    return bp;
}
  
  
/************************************************************************/
/* General log routine */
static void
ppp_log( ppp_p, comment )
struct ppp_s *ppp_p;
char *comment;
{
    if (ppp_p->trace)
        trace_log(ppp_p->iface,"%s PPP %s",
        ppp_p->iface->name,
        comment);
}
  
  
/* Bad packet */
static void
ppp_error(ppp_p, bp, comment)
struct ppp_s *ppp_p;
struct mbuf *bp;
char *comment;
{
    free_p(bp);
    ppp_log( ppp_p, comment );
}
  
  
/* Unknown type input packet */
static void
ppp_skipped(ppp_p, bp, comment)
struct ppp_s *ppp_p;
struct mbuf *bp;
char *comment;
{
    struct ipcp_s *ipcp_p;
  
    if ( (ipcp_p = ppp_p->fsm[IPcp].pdv) != NULL ) {
        slhc_toss( ipcp_p->slhcp );
    }
    ppp_error( ppp_p, bp, comment );
}
  
  
/****************************************************************************/
/* Send IP datagram with Point-to-Point Protocol */
int
ppp_send(bp,ifp,gateway,prec,del,tput,rel)
struct mbuf *bp;    /* Buffer to send */
struct iface *ifp;  /* Pointer to interface control block */
int32 gateway;      /* Ignored (PPP is point-to-point) */
int prec;
int del;
int tput;
int rel;
{
    struct ppp_s *ppp_p;
    struct ipcp_s *ipcp_p;
    int protocol = PPP_IP_PROTOCOL;
  
    if (ifp == NULLIF
    || (ppp_p = ifp->edv) == NULL) {
        free_p(bp);
        return -1;
    }
  
    if (ppp_p->fsm[IPcp].state != fsmOPENED) {
        ppp_error( ppp_p, bp, "not open for IP traffic" );
        ppp_p->OutError++;
        return -1;
    }
  
    ipcp_p = ppp_p->fsm[IPcp].pdv;
    if (ipcp_p->remote.work.negotiate & IPCP_N_COMPRESS) {
        /* Attempt IP/TCP header compression */
        switch ( slhc_compress(ipcp_p->slhcp, &bp,
        ipcp_p->remote.work.slot_compress) ) {
            case SL_TYPE_IP:
                protocol = PPP_IP_PROTOCOL;
                break;
            case SL_TYPE_COMPRESSED_TCP:
                protocol = PPP_COMPR_PROTOCOL;
                break;
            case SL_TYPE_UNCOMPRESSED_TCP:
                protocol = PPP_UNCOMP_PROTOCOL;
                break;
            default:
                ppp_error( ppp_p, bp, "bad IP packet" );
                ppp_p->OutError++;
                return -1;
        };
    }
    return (*ifp->output)(ifp,NULLCHAR,NULLCHAR,protocol,bp);
}
  
  
/* Send a packet with PPP header */
int
ppp_output(ifp,dest,source,protocol,data)
struct iface *ifp;  /* Pointer to interface control block */
char *dest;     /* Dest addr (ignored; PPP is point-to-point) */
char *source;       /* Source addr (ignored; PPP is point-to-point) */
int16 protocol;     /* PPP Protocol Type field */
struct mbuf *data;  /* Actual data to be sent */
{
    struct ppp_s *ppp_p;
    struct mbuf *bp;
    struct ppp_hdr hdr;
  
    if (ifp == NULLIF
    || (ppp_p = ifp->edv) == NULL) {
        free_p(data);
        return -1;
    }
  
    if (ppp_p->phase == pppDEAD) {
        ppp_error( ppp_p, data, "line not up" );
        ppp_p->OutError++;
        return -1;
    }
  
    hdr.addr = HDLC_ALL_ADDR;
    hdr.control = HDLC_UI;
    hdr.protocol = protocol;
  
    if ((bp = htonppp(&hdr, data)) == NULLBUF) {
        ppp_log( ppp_p, Nospace );
        ppp_p->OutMemory++;
        return -1;
    }
  
    return (*ifp->raw)(ifp,bp);
}
  
  
/* Encode a raw packet in PPP framing, put on link output queue */
static int
ppp_raw(ifp,bp)
struct iface *ifp;
struct mbuf *bp;
{
    struct ppp_s *ppp_p = ifp->edv;
    struct lcp_s *lcp_p = ppp_p->fsm[Lcp].pdv;
    int full_lcp, full_ac, full_p;
    int16 calc_fcs = HDLC_FCS_START;
    int32 accm = LCP_ACCM_DEFAULT;
    struct ppp_hdr ph;
    int len = PPP_HDR_LEN;
    struct mbuf *vbp;
    register char *cp;
    register int c;
  
    dump(ifp,IF_TRACE_OUT,CL_PPP,bp);
    ppp_p->OutTxOctetCount += len_p(bp) + 2;  /* count FCS bytes */
    ifp->rawsndcnt++;
    ifp->lastsent = secclock();
  
    /* Get the HDLC/PPP header, without actually pulling mbuf up */
    if ( bp == NULLBUF || bp->cnt < PPP_HDR_LEN ) {
        ppp_error( ppp_p, bp, "link header missing" );
        ppp_p->OutError++;
        return -1;
    }
  
    ph.addr = bp->data[0];
    ph.control = bp->data[1];
    ph.protocol = get16(&bp->data[2]);
  
    if ( ( full_lcp = (ph.protocol == PPP_LCP_PROTOCOL) ) == 0
    && (lcp_p->remote.work.negotiate & LCP_N_ACCM) ) {
        accm = lcp_p->remote.work.accm;
    }
  
    if ( ( full_p = ( full_lcp
        ||  !(lcp_p->remote.work.negotiate & LCP_N_PFC)
        ||  ph.protocol >= 0x00ff ) )
    == 0 ) {
        --len;
    }
  
    /* Discard HDLC address and control fields if possible */
    if ( ( full_ac = ( full_lcp
        ||  !(lcp_p->remote.work.negotiate & LCP_N_ACFC) ) )
    == 0 ) {
        len -= 2;
    }
  
    /* Load header with proper values */
    bp->cnt -= PPP_HDR_LEN - len;
    cp = (bp->data += PPP_HDR_LEN - len);
  
    if ( full_ac ) {
        *cp++ = ph.addr;
        *cp++ = ph.control;
    }
    if ( full_p )
        *cp++ = (ph.protocol >> 8);
    *cp++ = (ph.protocol & 0x00ff);
  
    /* Allocate output mbuf that's twice as long as the packet.
     * This is a worst-case guess (consider a packet full of HDLC_FLAGs!)
     */
    if ((vbp = alloc_mbuf((int16)(2*len_p(bp) + HDLC_ENVLEN))) == NULLBUF) {
        ppp_error( ppp_p, bp, Nospace );
        ppp_p->OutMemory++;
        return -1;
    }
    cp = vbp->data;
  
    /* No need to send an opening flag if the previous packet is still
     * being transmitted.
     */
#ifdef LINUX
    if (Asy[ifp->dev].sndq == 0) {
#else
        if ( Asy[ifp->dev].dma.flags == 0 ) {
#endif
        /* Flush out any line garbage */
            *cp++ = HDLC_FLAG;
            ppp_p->OutOpenFlag++;
        }
  
    /* Copy input to output, escaping special characters */
        while ((c = PULLCHAR(&bp)) != -1) {
        /* Fold char value into FCS calculated so far */
            calc_fcs = pppfcs(calc_fcs, c);
  
            if ( ((c < SP_CHAR) && (accm & (1L << c)))
                || (c == HDLC_ESC_ASYNC)
            || (c == HDLC_FLAG)) {
                *cp++ = HDLC_ESC_ASYNC;
                *cp++ = (c ^ HDLC_ESC_COMPL);
            } else {
                *cp++ = c;
            }
        }
  
    /* Final FCS calculation */
        calc_fcs ^= 0xffff;
        c = (calc_fcs & 0x00ff);    /* Least significant byte first */
        if ( ((c < SP_CHAR) && (accm & (1L << c)))
            ||(c == HDLC_ESC_ASYNC)
        ||(c == HDLC_FLAG)) {
            *cp++ = HDLC_ESC_ASYNC;
            *cp++ = (c ^ HDLC_ESC_COMPL);
        } else {
            *cp++ = c;
        }
        c = (calc_fcs >> 8);        /* Most significant byte next */
        if ( ((c < SP_CHAR) && (accm & (1L << c)))
            ||(c == HDLC_ESC_ASYNC)
        ||(c == HDLC_FLAG)) {
            *cp++ = HDLC_ESC_ASYNC;
            *cp++ = (c ^ HDLC_ESC_COMPL);
        } else {
            *cp++ = c;
        }
  
    /* Tie off the packet */
        *cp++ = HDLC_FLAG;
        vbp->cnt = cp - vbp->data;
  
        if (ifp->trace & IF_TRACE_RAW)
            raw_dump(ifp,IF_TRACE_OUT,vbp);
        return asy_send(ifp->dev,vbp);
    }
  
  
/****************************************************************************/
/* Packetize PPP input from device */
/* (process started by ppp_init) */
    void
    ppp_recv(dev,p1,p2)
    int dev;
    void *p1;
    void *p2;
    {
        struct iface *ifp = p1;
        struct ppp_s *ppp_p = ifp->edv;
        int32 accm = LCP_ACCM_DEFAULT;
        int16 calc_fcs = HDLC_FCS_START;
        struct mbuf *raw_bp = NULLBUF;
        struct mbuf *head_bp = NULLBUF;
        register struct mbuf *tail_bp = NULLBUF;
        char *cp;           /* next byte in tail mbuf */
        register int mode = FALSE;
        register int c;
  
        while ( (c = get_asy(dev)) != -1 ) {
#ifdef PPP_DEBUG_RAW
            if (ifp->trace & IF_TRACE_RAW) {
                if ( raw_bp != NULLBUF
                || (raw_bp = alloc_mbuf( LCP_MRU_HI * 2 )) != NULLBUF ) {
                    *raw_bp->data++ = c;
                    raw_bp->cnt++;
                    if ( raw_bp->cnt != 1 && c == HDLC_FLAG ) {
                        raw_bp->data = (char *)(raw_bp + 1);
                        raw_dump( ifp, IF_TRACE_IN, raw_bp );
                        raw_bp->cnt = 0;
                    }
                }
            }
#endif
            if ( c == HDLC_FLAG ) {
                if ( mode & PPP_ESCAPED ) {
                    ppp_skipped( ppp_p, head_bp,
                    "deliberate cancellation" );
                    ppp_p->InFrame++;
                } else if ( mode & PPP_TOSS ) {
                    free_p( head_bp );
                } else if ( head_bp != NULLBUF ) {
                    if ( calc_fcs != HDLC_FCS_FINAL ) {
                        ppp_skipped( ppp_p, head_bp,
                        "checksum error" );
                        ppp_p->InChecksum++;
                    } else {
                    /* trim off FCS bytes */
                        trim_mbuf(&head_bp, len_p(head_bp)-2);
  
                        net_route( ifp, CL_PPP, head_bp );
                    }
                } else {
                    ppp_p->InOpenFlag++;
                }
  
            /* setup for next buffer */
                mode = FALSE;
                head_bp = tail_bp = NULLBUF;
                calc_fcs = HDLC_FCS_START;
                accm = LCP_ACCM_DEFAULT;
  
            /* Use negotiated values if LCP finished */
                if (ppp_p->fsm[Lcp].state == fsmOPENED) {
                    struct lcp_s *lcp_p = ppp_p->fsm[Lcp].pdv;
  
                    if (lcp_p->local.work.negotiate & LCP_N_ACCM) {
                        accm = lcp_p->local.work.accm;
                    }
                }
#ifdef PPP_DEBUG_RAW
                if (!(ifp->trace & IF_TRACE_RAW)) {
                    if ( raw_bp != NULLBUF ) {
                        free_p( raw_bp );
                        raw_bp = NULLBUF;
                    }
                }
#endif
                continue;
            }
  
        /* We reach here for every byte inside a frame.
         * (The order of the following tests is important.)
         * Discard spurious control characters.
         * Check for escape sequence.
         * (Allow escaped escape.)
         */
            if ( c < SP_CHAR && (accm & (1L << c)) ) {
                continue;
            } else if ( mode & PPP_ESCAPED ) {
                mode &= ~PPP_ESCAPED;
                c ^= HDLC_ESC_COMPL;
            } else if ( c == HDLC_ESC_ASYNC ) {
                mode |= PPP_ESCAPED;
                continue;
            }
  
        /* We reach here with a byte for the buffer.
         * Make sure there is room for it.
         */
            if ( tail_bp == NULLBUF ) {
                if ((tail_bp = alloc_mbuf(PPP_ALLOC)) == NULLBUF) {
                    ppp_skipped( ppp_p, tail_bp, Nospace );
                    ppp_p->InMemory++;
                    mode |= PPP_TOSS;
                    continue;
                }
                head_bp = tail_bp;
                cp = tail_bp->data;
            } else if ( tail_bp->cnt >= tail_bp->size ) {
            /* Current mbuf is full */
                if ( (tail_bp->next = alloc_mbuf(PPP_ALLOC)) == NULLBUF ) {
                /* No memory, drop the whole packet */
                    ppp_skipped( ppp_p, head_bp, Nospace );
                    ppp_p->InMemory++;
                    head_bp = NULLBUF;
                    mode |= PPP_TOSS;
                    continue;
                }
                tail_bp = tail_bp->next;
                cp = tail_bp->data;
            }
  
        /* Store the byte, increment counts */
            *cp++ = c;
            tail_bp->cnt++;
            calc_fcs = pppfcs(calc_fcs, c);
        }
  
    /* clean up afterward */
        free_p(raw_bp);
        free_p(head_bp);
        ifp->rxproc = NULLPROC;
    }
  
#ifdef TURBOC_SWITCH_BUG
#pragma option -G-
#endif
  
/* Process incoming PPP packets */
/* (called from network task) */
    void
    ppp_proc(ifp,bp)
    struct iface *ifp;
    struct mbuf *bp;
    {
        struct ppp_s *ppp_p;
        struct ipcp_s *ipcp_p;
        struct ppp_hdr ph;
        struct mbuf *hbp;
        int16 negotiated = FALSE;
  
        if ( ifp == NULLIF ) {
            log(-1, "ppp_proc: missing iface" );
            return;
        }
        if ( bp == NULLBUF ) {
            trace_log(ifp, "ppp_proc: missing buffer" );
            return;
        }
  
        ppp_p = ifp->edv;
        ppp_p->InRxOctetCount += len_p(bp) + 2;   /* count FCS bytes */
  
    /* Use negotiated values if LCP finished */
        if (ppp_p->fsm[Lcp].state == fsmOPENED) {
            struct lcp_s *lcp_p = ppp_p->fsm[Lcp].pdv;
  
            negotiated = lcp_p->local.work.negotiate;
        }
  
    /* HDLC address and control fields may be compressed out */
        if ((byte_t)bp->data[0] != HDLC_ALL_ADDR) {
            if (!(negotiated & LCP_N_ACFC)) {
                ppp_skipped( ppp_p, bp, "missing ALL address" );
                ppp_p->InFrame++;
                return;
            }
        } else if ((byte_t)bp->data[1] != HDLC_UI) {
            if (!(negotiated & LCP_N_ACFC)
            || !(negotiated & LCP_N_PFC)) {
                ppp_skipped( ppp_p, bp, "missing UI" );
                ppp_p->InFrame++;
                return;
            }
        } else {
        /* skip address/control fields */
            pull16(&bp);
        }
  
    /* Initialize the expected header */
        ph.addr = HDLC_ALL_ADDR;
        ph.control = HDLC_UI;
        ph.protocol = PULLCHAR(&bp);
  
    /* First byte of PPP protocol field may be compressed out */
        if ( ph.protocol & 0x01 ) {
            if (!(negotiated & LCP_N_PFC)) {
                ppp_skipped( ppp_p, bp, "missing upper protocol byte" );
                ppp_p->InFrame++;
                return;
            }
        } else {
            ph.protocol = (ph.protocol << 8) | PULLCHAR(&bp);
  
        /* Second byte of PPP protocol field must be odd */
            if ( !(ph.protocol & 0x01) ) {
                ppp_skipped( ppp_p, bp, "missing lower protocol byte" );
                ppp_p->InFrame++;
                return;
            }
        }
  
  
        switch(ph.protocol) {
            case PPP_IP_PROTOCOL:   /* Regular IP */
                if ( ppp_p->fsm[IPcp].state != fsmOPENED ) {
                    ppp_error( ppp_p, bp, "not open for IP traffic" );
                    ppp_p->InError++;
                    break;
                }
                ip_route(ifp,bp,0);
                break;
  
            case PPP_COMPR_PROTOCOL:    /* Van Jacobson Compressed TCP/IP */
                if ( ppp_p->fsm[IPcp].state != fsmOPENED ) {
                    ppp_skipped( ppp_p, bp, "not open for Compressed TCP/IP traffic" );
                    ppp_p->InError++;
                    break;
                }
  
                ipcp_p = ppp_p->fsm[IPcp].pdv;
                if (!(ipcp_p->local.work.negotiate & IPCP_N_COMPRESS)) {
                    ppp_skipped( ppp_p, bp, "Compressed TCP/IP not enabled" );
                    ppp_p->InError++;
                    break;
                }
  
                if ( slhc_uncompress(ipcp_p->slhcp, &bp) <= 0 ) {
                    ppp_error( ppp_p, bp, "Compressed TCP/IP packet error" );
                    ppp_p->InError++;
                    break;
                }
                ip_route(ifp,bp,0);
                break;
  
            case PPP_UNCOMP_PROTOCOL:   /* Van Jacobson Uncompressed TCP/IP */
                if ( ppp_p->fsm[IPcp].state != fsmOPENED ) {
                    ppp_skipped( ppp_p, bp, "not open for Uncompressed TCP/IP traffic" );
                    ppp_p->InError++;
                    break;
                }
  
                ipcp_p = ppp_p->fsm[IPcp].pdv;
                if (!(ipcp_p->local.work.negotiate & IPCP_N_COMPRESS)) {
                    ppp_skipped( ppp_p, bp, "Uncompressed TCP/IP not enabled" );
                    ppp_p->InError++;
                    break;
                }
  
                if ( slhc_remember(ipcp_p->slhcp, &bp) <= 0 ) {
                    ppp_error( ppp_p, bp, "Uncompressed TCP/IP packet error" );
                    ppp_p->InError++;
                    break;
                }
                ip_route(ifp,bp,0);
                break;
  
            case PPP_LCP_PROTOCOL:  /* Link Control Protocol */
                ppp_p->InNCP[Lcp]++;
                fsm_proc(&(ppp_p->fsm[Lcp]),bp);
                break;
  
            case PPP_PAP_PROTOCOL:  /* Password Authenticate Protocol */
                if (ppp_p->phase != pppAP
                && ppp_p->phase != pppREADY) {
                    ppp_error( ppp_p, bp, "not ready for Authentication" );
                    ppp_p->InError++;
                    break;
                }
                ppp_p->InNCP[Pap]++;
                pap_proc(&(ppp_p->fsm[Pap]),bp);
                break;
  
            case PPP_IPCP_PROTOCOL: /* IP Control Protocol */
                if (ppp_p->phase != pppREADY) {
                    ppp_error( ppp_p, bp, "not ready for IPCP traffic" );
                    ppp_p->InError++;
                    break;
                }
                ppp_p->InNCP[IPcp]++;
                fsm_proc(&(ppp_p->fsm[IPcp]),bp);
                break;
  
            default:
                if ( ppp_p->trace )
                    trace_log(ppp_p->iface, "%s PPP Unknown packet protocol: %x;",
                    ppp_p->iface->name,
                    ph.protocol);
                ppp_p->InUnknown++;
  
        /* Build Protocol Reject packet:
         * put the header back on ...
         */
                if ((hbp = htonppp(&ph,bp)) == NULLBUF){
                    ppp_log( ppp_p, Nospace );
                    ppp_p->InMemory++;
                    return;
                }
        /* ... then pull off the address and control fields ... */
                pull16(&hbp);
        /* ... and send it as an LCP packet */
                fsm_send( &(ppp_p->fsm[Lcp]), PROT_REJ, 0, hbp );
                break;
        };
    }
  
#ifdef TURBOC_SWITCH_BUG
#pragma option -G
#endif
  
/************************************************************************/
  
/* Keep track of changes in I-O status */
/* (called through iface iostatus vector) */
    static int
    ppp_iostatus( ifp, command, value )
    struct iface *ifp;
    int command;
    int32 value;
    {
        struct ppp_s *ppp_p = ifp->edv;
  
        switch ( command ) {
            case PARAM_UP:
                ppp_log( ppp_p, "Physical layer up" );
  
                if ( ppp_p->phase == pppDEAD ) {
                    ppp_p->phase = pppLCP;
                }
                fsm_start( &(ppp_p->fsm[Lcp]) );
                return 0;
  
            case PARAM_DOWN:
                ppp_log( ppp_p, "Physical layer down" );
  
                fsm_down( &(ppp_p->fsm[Lcp]) );
                ppp_p->phase = pppDEAD;
                return 0;
        };
        return -1;
    }
  
  
    static int
    ppp_discard(ifp,bp)
    struct iface *ifp;
    struct mbuf *bp;
    {
        struct ppp_s *ppp_p = ifp->edv;
  
        return fsm_send(&(ppp_p->fsm[Lcp]), DISCARD_REQ, 0, bp);
    }
  
  
    static int
    ppp_echo(ifp,bp)
    struct iface *ifp;
    struct mbuf *bp;
    {
        struct ppp_s *ppp_p = ifp->edv;
  
        return fsm_send(&(ppp_p->fsm[Lcp]), ECHO_REQ, 0, bp);
    }
  
  
/****************************************************************************/
/* Initialize PPP control structures for a Point-to-Point interface */
    int
    ppp_init(ifp)
    struct iface *ifp;
    {
        struct ppp_s *ppp_p;
        char *ifn;
  
        ppp_p = callocw(1,sizeof(struct ppp_s));
  
        ifp->edv = ppp_p;
        ifp->iostatus = ppp_iostatus;
        ifp->raw = ppp_raw;
        ifp->show = ppp_show;
        ifp->echo = ppp_echo;
        ifp->discard = ppp_discard;
  
        ppp_p->iface = ifp;
        ppp_p->phase = pppDEAD;
  
        lcp_init(ppp_p);
        pap_init(ppp_p);
        ipcp_init(ppp_p);
  
        ifp->rxproc = newproc( ifn = if_name( ifp, " receive" ),
        320, ppp_recv, ifp->dev, ifp, NULL, 0);
        free(ifn);
        return 0;
    }
  
  
    int
    ppp_free(ifp)
    struct iface *ifp;
    {
        struct ppp_s *ppp_p = ifp->edv;
        int fsmi;
  
        alert( ifp->rxproc, -1 );
  
        for ( fsmi = Lcp; fsmi < fsmi_Size; ) {
            fsm_free( &(ppp_p->fsm[fsmi++]) );
        }
        free( ppp_p->peername );
        free( ppp_p );
        return 0;
    }
#endif /* PPP */
  
