ccp.c

自己精简过的PPPD代码。在嵌入中应用可以更好的发挥。比原先的小了很多

		/* Check state opt */
		if (ho->mppe & MPPE_OPT_STATEFUL) {
		    /*
		     * We can Nak and request stateless, but it's a
		     * lot easier to just assume the peer will request
		     * it if he can do it; stateful mode is bad over
		     * the Internet -- which is where we expect MPPE.
		     */
		   if (refuse_mppe_stateful) {
			error("Refusing MPPE stateful mode offered by peer");
			newret = CONFREJ;
			break;
		    }
		}

		/* Find out which of {S,L} are set. */
		if ((ho->mppe & MPPE_OPT_128)
		     && (ho->mppe & MPPE_OPT_40)) {
		    /* Both are set, negotiate the strongest. */
		    newret = CONFNAK;
		    if (ao->mppe & MPPE_OPT_128)
			ho->mppe &= ~MPPE_OPT_40;
		    else if (ao->mppe & MPPE_OPT_40)
			ho->mppe &= ~MPPE_OPT_128;
		    else {
			newret = CONFREJ;
			break;
		    }
		} else if (ho->mppe & MPPE_OPT_128) {
		    if (!(ao->mppe & MPPE_OPT_128)) {
			newret = CONFREJ;
			break;
		    }
		} else if (ho->mppe & MPPE_OPT_40) {
		    if (!(ao->mppe & MPPE_OPT_40)) {
			newret = CONFREJ;
			break;
		    }
		} else {
		    /* Neither are set. */
		    /* We cannot accept this.  */
		    newret = CONFNAK;
		    /* Give the peer our idea of what can be used,
		       so it can choose and confirm */
		    ho->mppe = ao->mppe;
		}

		/* rebuild the opts */
		MPPE_OPTS_TO_CI(ho->mppe, &p[2]);
		if (newret == CONFACK) {
		    u_char opt_buf[CILEN_MPPE + MPPE_MAX_KEY_LEN];
		    int mtu;

		    BCOPY(p, opt_buf, CILEN_MPPE);
		    BCOPY(mppe_send_key, &opt_buf[CILEN_MPPE],
			  MPPE_MAX_KEY_LEN);
		    if (ccp_test(f->unit, opt_buf,
				 CILEN_MPPE + MPPE_MAX_KEY_LEN, 1) <= 0) {
			/* This shouldn't happen, we've already tested it! */
			error("MPPE required, but kernel has no support.");
			lcp_close(f->unit, "MPPE required but not available");
			newret = CONFREJ;
			break;
		    }
		    /*
		     * We need to decrease the interface MTU by MPPE_PAD
		     * because MPPE frames **grow**.  The kernel [must]
		     * allocate MPPE_PAD extra bytes in xmit buffers.
		     */
		    mtu = netif_get_mtu(f->unit);
		    if (mtu)
			netif_set_mtu(f->unit, mtu - MPPE_PAD);
		    else
			newret = CONFREJ;
		}

		/*
		 * We have accepted MPPE or are willing to negotiate
		 * MPPE parameters.  A CONFREJ is due to subsequent
		 * (non-MPPE) processing.
		 */
		rej_for_ci_mppe = 0;
		break;
#endif /* MPPE */
	    case CI_DEFLATE:
	    case CI_DEFLATE_DRAFT:
		if (!ao->deflate || clen != CILEN_DEFLATE
		    || (!ao->deflate_correct && type == CI_DEFLATE)
		    || (!ao->deflate_draft && type == CI_DEFLATE_DRAFT)) {
		    newret = CONFREJ;
		    break;
		}

		ho->deflate = 1;
		ho->deflate_size = nb = DEFLATE_SIZE(p[2]);
		if (DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL
		    || p[3] != DEFLATE_CHK_SEQUENCE
		    || nb > ao->deflate_size || nb < DEFLATE_MIN_WORKS) {
		    newret = CONFNAK;
		    if (!dont_nak) {
			p[2] = DEFLATE_MAKE_OPT(ao->deflate_size);
			p[3] = DEFLATE_CHK_SEQUENCE;
			/* fall through to test this #bits below */
		    } else
			break;
		}

		/*
		 * Check whether we can do Deflate with the window
		 * size they want.  If the window is too big, reduce
		 * it until the kernel can cope and nak with that.
		 * We only check this for the first option.
		 */
		if (p == p0) {
		    for (;;) {
			res = ccp_test(f->unit, p, CILEN_DEFLATE, 1);
			if (res > 0)
			    break;		/* it's OK now */
			if (res < 0 || nb == DEFLATE_MIN_WORKS || dont_nak) {
			    newret = CONFREJ;
			    p[2] = DEFLATE_MAKE_OPT(ho->deflate_size);
			    break;
			}
			newret = CONFNAK;
			--nb;
			p[2] = DEFLATE_MAKE_OPT(nb);
		    }
		}
		break;

	    case CI_BSD_COMPRESS:
		if (!ao->bsd_compress || clen != CILEN_BSD_COMPRESS) {
		    newret = CONFREJ;
		    break;
		}

		ho->bsd_compress = 1;
		ho->bsd_bits = nb = BSD_NBITS(p[2]);
		if (BSD_VERSION(p[2]) != BSD_CURRENT_VERSION
		    || nb > ao->bsd_bits || nb < BSD_MIN_BITS) {
		    newret = CONFNAK;
		    if (!dont_nak) {
			p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, ao->bsd_bits);
			/* fall through to test this #bits below */
		    } else
			break;
		}

		/*
		 * Check whether we can do BSD-Compress with the code
		 * size they want.  If the code size is too big, reduce
		 * it until the kernel can cope and nak with that.
		 * We only check this for the first option.
		 */
		if (p == p0) {
		    for (;;) {
			res = ccp_test(f->unit, p, CILEN_BSD_COMPRESS, 1);
			if (res > 0)
			    break;
			if (res < 0 || nb == BSD_MIN_BITS || dont_nak) {
			    newret = CONFREJ;
			    p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION,
						ho->bsd_bits);
			    break;
			}
			newret = CONFNAK;
			--nb;
			p[2] = BSD_MAKE_OPT(BSD_CURRENT_VERSION, nb);
		    }
		}
		break;

	    case CI_PREDICTOR_1:
		if (!ao->predictor_1 || clen != CILEN_PREDICTOR_1) {
		    newret = CONFREJ;
		    break;
		}

		ho->predictor_1 = 1;
		if (p == p0
		    && ccp_test(f->unit, p, CILEN_PREDICTOR_1, 1) <= 0) {
		    newret = CONFREJ;
		}
		break;

	    case CI_PREDICTOR_2:
		if (!ao->predictor_2 || clen != CILEN_PREDICTOR_2) {
		    newret = CONFREJ;
		    break;
		}

		ho->predictor_2 = 1;
		if (p == p0
		    && ccp_test(f->unit, p, CILEN_PREDICTOR_2, 1) <= 0) {
		    newret = CONFREJ;
		}
		break;

	    default:
		newret = CONFREJ;
	    }
	}

	if (newret == CONFNAK && dont_nak)
	    newret = CONFREJ;
	if (!(newret == CONFACK || (newret == CONFNAK && ret == CONFREJ))) {
	    /* we're returning this option */
	    if (newret == CONFREJ && ret == CONFNAK)
		retp = p0;
	    ret = newret;
	    if (p != retp)
		BCOPY(p, retp, clen);
	    retp += clen;
	}

	p += clen;
	len -= clen;
    }

    if (ret != CONFACK) {
	if (ret == CONFREJ && *lenp == retp - p0)
	    all_rejected[f->unit] = 1;
	else
	    *lenp = retp - p0;
    }
#ifdef MPPE
    if (ret == CONFREJ && ao->mppe && rej_for_ci_mppe) {
	error("MPPE required but peer negotiation failed");
	lcp_close(f->unit, "MPPE required but peer negotiation failed");
    }
#endif
    return ret;
}

/*
 * Make a string name for a compression method (or 2).
 */
static char *
method_name(opt, opt2)
    ccp_options *opt, *opt2;
{
    static char result[64];

    if (!ANY_COMPRESS(*opt))
	return "(none)";
    switch (opt->method) {
#ifdef MPPE
    case CI_MPPE:
    {
	char *p = result;
	char *q = result + sizeof(result); /* 1 past result */

	slprintf(p, q - p, "MPPE ");
	p += 5;
	if (opt->mppe & MPPE_OPT_128) {
	    slprintf(p, q - p, "128-bit ");
	    p += 8;
	}
	if (opt->mppe & MPPE_OPT_40) {
	    slprintf(p, q - p, "40-bit ");
	    p += 7;
	}
	if (opt->mppe & MPPE_OPT_STATEFUL)
	    slprintf(p, q - p, "stateful");
	else
	    slprintf(p, q - p, "stateless");

	break;
    }
#endif
    case CI_DEFLATE:
    case CI_DEFLATE_DRAFT:
	if (opt2 != NULL && opt2->deflate_size != opt->deflate_size)
	    slprintf(result, sizeof(result), "Deflate%s (%d/%d)",
		     (opt->method == CI_DEFLATE_DRAFT? "(old#)": ""),
		     opt->deflate_size, opt2->deflate_size);
	else
	    slprintf(result, sizeof(result), "Deflate%s (%d)",
		     (opt->method == CI_DEFLATE_DRAFT? "(old#)": ""),
		     opt->deflate_size);
	break;
    case CI_BSD_COMPRESS:
	if (opt2 != NULL && opt2->bsd_bits != opt->bsd_bits)
	    slprintf(result, sizeof(result), "BSD-Compress (%d/%d)",
		     opt->bsd_bits, opt2->bsd_bits);
	else
	    slprintf(result, sizeof(result), "BSD-Compress (%d)",
		     opt->bsd_bits);
	break;
    case CI_PREDICTOR_1:
	return "Predictor 1";
    case CI_PREDICTOR_2:
	return "Predictor 2";
    default:
	slprintf(result, sizeof(result), "Method %d", opt->method);
    }
    return result;
}

/*
 * CCP has come up - inform the kernel driver and log a message.
 */
static void
ccp_up(f)
    fsm *f;
{
    ccp_options *go = &ccp_gotoptions[f->unit];
    ccp_options *ho = &ccp_hisoptions[f->unit];
    char method1[64];

    ccp_flags_set(f->unit, 1, 1);
    if (ANY_COMPRESS(*go)) {
	if (ANY_COMPRESS(*ho)) {
	    if (go->method == ho->method) {
		notice("%s compression enabled", method_name(go, ho));
	    } else {
		strlcpy(method1, method_name(go, NULL), sizeof(method1));
		notice("%s / %s compression enabled",
		       method1, method_name(ho, NULL));
	    }
	} else
	    notice("%s receive compression enabled", method_name(go, NULL));
    } else if (ANY_COMPRESS(*ho))
	notice("%s transmit compression enabled", method_name(ho, NULL));
#ifdef MPPE
    if (go->mppe) {
	BZERO(mppe_recv_key, MPPE_MAX_KEY_LEN);
	BZERO(mppe_send_key, MPPE_MAX_KEY_LEN);
	continue_networks(f->unit);		/* Bring up IP et al */
    }
#endif
}

/*
 * CCP has gone down - inform the kernel driver.
 */
static void
ccp_down(f)
    fsm *f;
{
    if (ccp_localstate[f->unit] & RACK_PENDING)
	UNTIMEOUT(ccp_rack_timeout, f);
    ccp_localstate[f->unit] = 0;
    ccp_flags_set(f->unit, 1, 0);
#ifdef MPPE
    if (ccp_gotoptions[f->unit].mppe) {
	ccp_gotoptions[f->unit].mppe = 0;
	if (lcp_fsm[f->unit].state == OPENED) {
	    /* If LCP is not already going down, make sure it does. */
	    error("MPPE disabled");
	    lcp_close(f->unit, "MPPE disabled");
	}
    }
#endif
}

/*
 * Print the contents of a CCP packet.
 */
static char *ccp_codenames[] = {
    "ConfReq", "ConfAck", "ConfNak", "ConfRej",
    "TermReq", "TermAck", "CodeRej",
    NULL, NULL, NULL, NULL, NULL, NULL,
    "ResetReq", "ResetAck",
};

static int
ccp_printpkt(p, plen, printer, arg)
    u_char *p;
    int plen;
    void (*printer) __P((void *, char *, ...));
    void *arg;
{
    u_char *p0, *optend;
    int code, id, len;
    int optlen;

    p0 = p;
    if (plen < HEADERLEN)
	return 0;
    code = p[0];
    id = p[1];
    len = (p[2] << 8) + p[3];
    if (len < HEADERLEN || len > plen)
	return 0;

    if (code >= 1 && code <= sizeof(ccp_codenames) / sizeof(char *)
	&& ccp_codenames[code-1] != NULL)
	printer(arg, " %s", ccp_codenames[code-1]);
    else
	printer(arg, " code=0x%x", code);
    printer(arg, " id=0x%x", id);
    len -= HEADERLEN;
    p += HEADERLEN;

    switch (code) {
    case CONFREQ:
    case CONFACK:
    case CONFNAK:
    case CONFREJ:
	/* print list of possible compression methods */
	while (len >= 2) {
	    code = p[0];
	    optlen = p[1];
	    if (optlen < 2 || optlen > len)
		break;
	    printer(arg, " <");
	    len -= optlen;
	    optend = p + optlen;
	    switch (code) {
#ifdef MPPE
	    case CI_MPPE:
		if (optlen >= CILEN_MPPE) {
		    u_char mppe_opts;

		    MPPE_CI_TO_OPTS(&p[2], mppe_opts);
		    printer(arg, "mppe %s %s %s %s %s %s%s",
			    (p[2] & MPPE_H_BIT)? "+H": "-H",
			    (p[5] & MPPE_M_BIT)? "+M": "-M",
			    (p[5] & MPPE_S_BIT)? "+S": "-S",
			    (p[5] & MPPE_L_BIT)? "+L": "-L",
			    (p[5] & MPPE_D_BIT)? "+D": "-D",
			    (p[5] & MPPE_C_BIT)? "+C": "-C",
			    (mppe_opts & MPPE_OPT_UNKNOWN)? " +U": "");
		    if (mppe_opts & MPPE_OPT_UNKNOWN)
			printer(arg, " (%.2x %.2x %.2x %.2x)",
				p[2], p[3], p[4], p[5]);
		    p += CILEN_MPPE;
		}
		break;
#endif
	    case CI_DEFLATE:
	    case CI_DEFLATE_DRAFT:
		if (optlen >= CILEN_DEFLATE) {
		    printer(arg, "deflate%s %d",
			    (code == CI_DEFLATE_DRAFT? "(old#)": ""),
			    DEFLATE_SIZE(p[2]));
		    if (DEFLATE_METHOD(p[2]) != DEFLATE_METHOD_VAL)
			printer(arg, " method %d", DEFLATE_METHOD(p[2]));
		    if (p[3] != DEFLATE_CHK_SEQUENCE)
			printer(arg, " check %d", p[3]);
		    p += CILEN_DEFLATE;
		}
		break;
	    case CI_BSD_COMPRESS:
		if (optlen >= CILEN_BSD_COMPRESS) {
		    printer(arg, "bsd v%d %d", BSD_VERSION(p[2]),
			    BSD_NBITS(p[2]));
		    p += CILEN_BSD_COMPRESS;
		}
		break;
	    case CI_PREDICTOR_1:
		if (optlen >= CILEN_PREDICTOR_1) {
		    printer(arg, "predictor 1");
		    p += CILEN_PREDICTOR_1;
		}
		break;
	    case CI_PREDICTOR_2:
		if (optlen >= CILEN_PREDICTOR_2) {
		    printer(arg, "predictor 2");
		    p += CILEN_PREDICTOR_2;
		}
		break;
	    }
	    while (p < optend)
		printer(arg, " %.2x", *p++);
	    printer(arg, ">");
	}
	break;

    case TERMACK:
    case TERMREQ:
	if (len > 0 && *p >= ' ' && *p < 0x7f) {
	    print_string((char *)p, len, printer, arg);
	    p += len;
	    len = 0;
	}
	break;
    }

    /* dump out the rest of the packet in hex */
    while (--len >= 0)
	printer(arg, " %.2x", *p++);

    return p - p0;
}

/*
 * We have received a packet that the decompressor failed to
 * decompress.  Here we would expect to issue a reset-request, but
 * Motorola has a patent on resetting the compressor as a result of
 * detecting an error in the decompressed data after decompression.
 * (See US patent 5,130,993; international patent publication number
 * WO 91/10289; Australian patent 73296/91.)
 *
 * So we ask the kernel whether the error was detected after
 * decompression; if it was, we take CCP down, thus disabling
 * compression :-(, otherwise we issue the reset-request.
 */
static void
ccp_datainput(unit, pkt, len)
    int unit;
    u_char *pkt;
    int len;
{
    fsm *f;

    f = &ccp_fsm[unit];
    if (f->state == OPENED) {
	if (ccp_fatal_error(unit)) {
	    /*
	     * Disable compression by taking CCP down.
	     */
	    error("Lost compression sync: disabling compression");
	    ccp_close(unit, "Lost compression sync");
#ifdef MPPE
	    /*
	     * If we were doing MPPE, we must also take the link down.
	     */
	    if (ccp_gotoptions[unit].mppe) {
		error("Too many MPPE errors, closing LCP");
		lcp_close(unit, "Too many MPPE errors");
	    }
#endif
	} else {
	    /*
	     * Send a reset-request to reset the peer's compressor.
	     * We don't do that if we are still waiting for an
	     * acknowledgement to a previous reset-request.
	     */
	    if (!(ccp_localstate[f->unit] & RACK_PENDING)) {
		fsm_sdata(f, CCP_RESETREQ, f->reqid = ++f->id, NULL, 0);
		TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
		ccp_localstate[f->unit] |= RACK_PENDING;
	    } else
		ccp_localstate[f->unit] |= RREQ_REPEAT;
	}
    }
}

/*
 * Timeout waiting for reset-ack.
 */
static void
ccp_rack_timeout(arg)
    void *arg;
{
    fsm *f = arg;

    if (f->state == OPENED && ccp_localstate[f->unit] & RREQ_REPEAT) {
	fsm_sdata(f, CCP_RESETREQ, f->reqid, NULL, 0);
	TIMEOUT(ccp_rack_timeout, f, RACKTIMEOUT);
	ccp_localstate[f->unit] &= ~RREQ_REPEAT;
    } else
	ccp_localstate[f->unit] &= ~RACK_PENDING;
}