/*
 * input.c
 *
 * Written by Archie Cobbs <archie@freebsd.org>
 * Copyright (c) 1995-1999 Whistle Communications, Inc. All rights reserved.
 * See ``COPYRIGHT.whistle''
 */

#include "ppp.h"
#include "input.h"
#include "ipcp.h"
#include "chap.h"
#include "pap.h"
#include "eap.h"
#include "lcp.h"
#include "ip.h"
#include "ccp.h"
#include "ecp.h"
#include "ngfunc.h"

/*
 * INTERNAL FUNCTIONS
 */

  static int	InputLinkCheck(Link l, int proto);
  static void	InputMPLink(Bund b, int proto, Mbuf pkt);
  static int	InputDispatch(Bund b, Link l, int proto, Mbuf bp);

/*
 * InputFrame()
 *
 * Input a PPP frame having protocol "proto" from link "linkNum",
 * which may be either a link number or NG_PPP_BUNDLE_LINKNUM.
 * This always consumes the mbuf.
 */

void
InputFrame(Bund b, Link l, int proto, Mbuf bp)
{
    Mbuf	protoRej;
    u_int16_t	nprot;

    /* Check the link */
    if (l == NULL) {
	/* Only limited link-layer stuff allowed over the MP bundle */
	if (PROT_LINK_LAYER(proto)) {
    	    InputMPLink(b, proto, bp);
    	    return;
	}
    } else {
	/* Check protocol vs. link state */
	if (!InputLinkCheck(l, proto)) {
    	    mbfree(bp);
    	    return;
	}
    }

    /* Dispatch frame to the appropriate protocol engine */
    if (InputDispatch(b, l, proto, bp) >= 0)
	return;

    /* Unknown protocol, so find a link to send protocol reject on */
    if (l == NULL) {
	int	k;
	for (k = 0; k < NG_PPP_MAX_LINKS && 
	    (!b->links[k] || b->links[k]->lcp.phase != PHASE_NETWORK);
    	    k++);
	if (k == NG_PPP_MAX_LINKS) {
    	    mbfree(bp);
    	    return;
	}
	l = b->links[k];
    }

    /* Send a protocol reject on the chosen link */
    nprot = htons((u_int16_t) proto);
    protoRej = mbcopyback(bp, -2, (u_char *) &nprot, 2);
    FsmOutputMbuf(&l->lcp.fsm, CODE_PROTOREJ, l->lcp.fsm.rejid++, protoRej);
}

/*
 * InputDispatch()
 *
 * Given an unwrapped PPP frame of type "proto", dispatch to wherever.
 * Returns negative if protocol was unknown, otherwise returns zero
 * and consumes packet. Any packets we expect the peer to send but
 * shouldn't be received by this daemon are logged and dropped.
 */

static int
InputDispatch(Bund b, Link l, int proto, Mbuf bp)
{
    int reject = 0;

    /* link level protos */
    if (l) {
	switch (proto) {
        case PROTO_LCP:
            LcpInput(l, bp);
            return(0);
        case PROTO_PAP:
        case PROTO_CHAP:
        case PROTO_EAP:
            AuthInput(l, proto, bp);
            return(0);
	case PROTO_MP:
    	    if (!Enabled(&l->conf.options, LINK_CONF_MULTILINK))
		reject = 1;
    	    goto done;
        }
    }

    /* bundle level protos */
    if (b) {
	switch (proto) {
	case PROTO_IPCP:
	case PROTO_IP:
        case PROTO_VJUNCOMP:
        case PROTO_VJCOMP:
    	    if (!Enabled(&b->conf.options, BUND_CONF_IPCP))
		reject = 1;
    	    else if (proto == PROTO_IPCP) {
    		IpcpInput(b, bp);
    		return(0);
    	    }
    	    break;
	case PROTO_IPV6CP:
	case PROTO_IPV6:
    	    if (!Enabled(&b->conf.options, BUND_CONF_IPV6CP))
		reject = 1;
    	    else if (proto == PROTO_IPV6CP) {
    		Ipv6cpInput(b, bp);
    		return(0);
    	    }
    	    break;
	case PROTO_CCP:
	case PROTO_COMPD:
    	    if (!Enabled(&b->conf.options, BUND_CONF_COMPRESSION))
		reject = 1;
    	    else if (proto == PROTO_CCP) {
		CcpInput(b, bp);
		return(0);
    	    }
    	    break;
	case PROTO_ECP:
	case PROTO_CRYPT:
    	    if (!Enabled(&b->conf.options, BUND_CONF_ENCRYPTION))
		reject = 1;
    	    else if (proto == PROTO_ECP) {
		EcpInput(b, bp);
		return(0);
    	    }
    	    break;
	default:	/* completely unknown protocol, reject it */
    	    reject = 1;
    	    break;
	}
    }

done:
    /* Protocol unexpected, so either reject or drop */
    Log(LG_LINK|LG_BUND, ("[%s] rec'd unexpected protocol %s%s",
	(l ? l->name : b->name), ProtoName(proto), reject ? ", rejecting" : ""));
    if (!reject)
	mbfree(bp);
    return (reject ? -1 : 0);
}

/*
 * InputLinkCheck()
 *
 * Make sure this protocol is acceptable and makes sense on this link.
 * Returns TRUE if so and the frame should be handled further.
 */

static int
InputLinkCheck(Link l, int proto)
{
  /* Check link LCP state */
  switch (l->lcp.phase) {
    case PHASE_DEAD:
      Log(LG_LINK, ("[%s] rec'd proto %s while dead",
	l->name, ProtoName(proto)));
      return(FALSE);
    case PHASE_ESTABLISH:
      if (proto != PROTO_LCP) {
	Log(LG_LINK, ("[%s] rec'd proto %s during establishment phase",
	  l->name, ProtoName(proto)));
	return(FALSE);
      }
      break;
    case PHASE_AUTHENTICATE:
      if (!PROT_LINK_LAYER(proto)) {
	Log(LG_LINK, ("[%s] rec'd proto %s during authenticate phase",
	  l->name, ProtoName(proto)));
	return(FALSE);
      }
      break;
    case PHASE_NETWORK:
      break;
    case PHASE_TERMINATE:
      if (proto != PROTO_LCP) {
	Log(LG_LINK, ("[%s] rec'd proto %s during terminate phase",
	  l->name, ProtoName(proto)));
	return(FALSE);
      }
      break;
    default:
      assert(0);
  }

  /* OK */
  return(TRUE);
}

/*
 * InputMPLink()
 *
 * Deal with an incoming link-level packet on the virtual link (!)
 * Only certain link-level packets make sense coming over the bundle.
 * In any case, this consumes the mbuf.
 */

static void
InputMPLink(Bund b, int proto, Mbuf pkt)
{
    struct fsmheader	*hdr;
    int			k;

    switch (proto) {
	case PROTO_LCP:
    	    if (MBLEN(pkt) < sizeof(hdr))
		break;
    	    hdr = (struct fsmheader *)(void *)MBDATA(pkt);
    	    switch (hdr->code) {
		case CODE_CODEREJ:		/* these two are OK */
		case CODE_PROTOREJ:
		    for (k = 0; k < NG_PPP_MAX_LINKS && !b->links[k]; k++)
		    if (k < NG_PPP_MAX_LINKS) {
			InputFrame(b, b->links[k], proto, pkt);
			return;
		    }
		    break;

		case CODE_ECHOREQ:
		    Log(LG_ECHO, ("[%s] rec'd %s #%d, replying...",
			b->name, FsmCodeName(hdr->code), hdr->id));
		    MBDATAU(pkt)[0] = CODE_ECHOREP;
		    NgFuncWritePppFrame(b, NG_PPP_BUNDLE_LINKNUM, PROTO_LCP, pkt);
		    return;

		case CODE_ECHOREP:
		    Log(LG_ECHO, ("[%s] rec'd %s #%d",
			b->name, FsmCodeName(hdr->code), hdr->id));
		    break;

	        default:
		    Log(LG_ERR, ("[%s] rec'd LCP %s #%d on MP link! (ignoring)",
			b->name, FsmCodeName(hdr->code), hdr->id));
		    break;
	    }
	    break;

	default:
    	    Log(LG_ERR, ("[%s] rec'd proto %s on MP link! (ignoring)",
		b->name, ProtoName(proto)));
    	    break;
    }
    mbfree(pkt);
}