/*
 * multilink.c - support routines for multilink.
 *
 * Copyright (c) 2000-2001 by Sun Microsystems, Inc.
 * All rights reserved.
 *
 * Copyright (c) 2000 Paul Mackerras.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms.  The name of the author may not be
 * used to endorse or promote products derived from this software
 * without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <netdb.h>
#include <errno.h>
#include <signal.h>
#include <netinet/in.h>

#include "pppd.h"
#include "fsm.h"
#include "lcp.h"

#ifdef HAVE_MULTILINK
#include "tdb.h"
#endif

#define set_ip_epdisc(ep, addr) (       \
        ep->length = 4,                 \
        ep->value[0] = addr >> 24,      \
        ep->value[1] = addr >> 16,      \
        ep->value[2] = addr >> 8,       \
        ep->value[3] = addr             \
)

#ifdef HAVE_MULTILINK
bool endpoint_specified;        /* user gave explicit endpoint discriminator */
char *bundle_id;                /* identifier for our bundle */

static int get_default_epdisc __P((struct epdisc *));
static int parse_num __P((char *str, const char *key, int *valp));
static int owns_unit __P((TDB_DATA pid, int unit));

#define process_exists(n)       (kill(0, (n)) == 0 || errno != ESRCH)

void
mp_check_options()
{
        lcp_options *wo = &lcp_wantoptions[0];
        lcp_options *ao = &lcp_allowoptions[0];

        if (!multilink)
                return;
        /* if we're doing multilink, we have to negotiate MRRU */
        if (!wo->neg_mrru) {
                /* mrru not specified, default to mru */
                wo->mrru = wo->mru;
                wo->neg_mrru = 1;
        }
        ao->mrru = ao->mru;
        ao->neg_mrru = 1;

        if (!wo->neg_endpoint && !noendpoint) {
                /* get a default endpoint value */
                wo->neg_endpoint = get_default_epdisc(&wo->endpoint);
                if (wo->neg_endpoint)
                        dbglog("using default endpoint %s",
                               epdisc_to_str(&wo->endpoint));
        }
}

/*
 * Make a new bundle or join us to an existing bundle
 * if we are doing multilink.
 */
int
mp_join_bundle()
{
        lcp_options *go = &lcp_gotoptions[0];
        lcp_options *ho = &lcp_hisoptions[0];
        int unit, pppd_pid;
        int l;
        char *p;
        TDB_DATA key, pid, rec;

        if (!go->neg_mrru || !ho->neg_mrru) {
                /* not doing multilink */
                if (go->neg_mrru)
                        notice("oops, multilink negotiated only for receive");
                multilink = 0;
                if (demand) {
                        /* already have a bundle */
                        cfg_bundle(0, 0, 0, 0);
                        return 0;
                }
                make_new_bundle(0, 0, 0, 0);
                set_ifunit(1);
                return 0;
        }

        /*
         * Find the appropriate bundle or join a new one.
         * First we make up a name for the bundle.
         * The length estimate is worst-case assuming every
         * character has to be quoted.
         *
         * Note - RFC 1990 requires that an unnegotiated endpoint
         * discriminator value be equivalent to negotiating with class
         * zero.  Do not test ho->neg_endpoint here.
         */
        l = 4 * strlen(peer_authname) + 10;
        l += 3 * ho->endpoint.length + 8;
        if (bundle_name)
                l += 3 * strlen(bundle_name) + 2;
        bundle_id = malloc(l);
        if (bundle_id == NULL)
                novm("bundle identifier");

        p = bundle_id;
        p += slprintf(p, l-1, "BUNDLE=\"%q\"", peer_authname);
        *p++ = '/';
        p += slprintf(p, bundle_id+l-p, "%s", epdisc_to_str(&ho->endpoint));
        if (bundle_name)
                p += slprintf(p, bundle_id+l-p, "/%v", bundle_name);
        dbglog("bundle_id = %s", bundle_id+7);

        /*
         * For demand mode, we only need to configure the bundle
         * and attach the link.
         */
        if (demand) {
                cfg_bundle(go->mrru, ho->mrru, go->neg_ssnhf, ho->neg_ssnhf);
                script_setenv("BUNDLE", bundle_id + 7, 1);
                return 0;
        }

        /*
         * Check if the bundle ID is already in the database.
         */
        unit = -1;
        tdb_writelock(pppdb);
        key.dptr = bundle_id;
        key.dsize = p - bundle_id;
        pid = tdb_fetch(pppdb, key);
        if (pid.dptr != NULL) {
                /* bundle ID exists, see if the pppd record exists */
                rec = tdb_fetch(pppdb, pid);
                if (rec.dptr != NULL) {
                        /* it does, parse the interface number */
                        parse_num(rec.dptr, "IFNAME=ppp", &unit);
                        /* check the pid value */
                        if (!parse_num(rec.dptr, "PPPD_PID=", &pppd_pid)
                            || !process_exists(pppd_pid)
                            || !owns_unit(pid, unit))
                                unit = -1;
                        free(rec.dptr);
                }
                free(pid.dptr);
        }

        if (unit >= 0) {
                /* attach to existing unit */
                if (bundle_attach(unit)) {
                        set_ifunit(0);
                        script_setenv("BUNDLE", bundle_id + 7, 0);
                        tdb_writeunlock(pppdb);
                        info("Link attached to %s", ifname);
                        return 1;
                }
                /* attach failed because bundle doesn't exist */
        }

        /* we have to make a new bundle */
        make_new_bundle(go->mrru, ho->mrru, go->neg_ssnhf, ho->neg_ssnhf);
        set_ifunit(1);
        script_setenv("BUNDLE", bundle_id + 7, 1);
        tdb_writeunlock(pppdb);
        info("New bundle %s created", ifname);
        return 0;
}

static int
parse_num(str, key, valp)
     char *str;
     const char *key;
     int *valp;
{
        char *p, *endp;
        int i;

        p = strstr(str, key);
        if (p != 0) {
                p += strlen(key);
                i = strtol(p, &endp, 10);
                if (endp != p && (*endp == 0 || *endp == ';')) {
                        *valp = i;
                        return 1;
                }
        }
        return 0;
}

/*
 * Check whether the pppd identified by `key' still owns ppp unit `unit'.
 */
static int
owns_unit(key, unit)
     TDB_DATA key;
     int unit;
{
        char ifkey[32];
        TDB_DATA kd, vd;
        int ret = 0;

        (void) slprintf(ifkey, sizeof(ifkey), "IFNAME=ppp%d", unit);
        kd.dptr = ifkey;
        kd.dsize = strlen(ifkey);
        vd = tdb_fetch(pppdb, kd);
        if (vd.dptr != NULL) {
                ret = vd.dsize == key.dsize
                        && memcmp(vd.dptr, key.dptr, vd.dsize) == 0;
                free(vd.dptr);
        }
        return ret;
}

static int
get_default_epdisc(ep)
     struct epdisc *ep;
{
        struct hostent *hp;
        u_int32_t addr;

        if (get_first_hwaddr(ep->value, sizeof(ep->value))) {
                ep->class = EPD_MAC;
                ep->length = 6;
                return 1;
        }

        /* see if our hostname corresponds to a reasonable IP address */
        hp = gethostbyname(hostname);
        if (hp != NULL) {
                addr = *(u_int32_t *)hp->h_addr;
                if (!bad_ip_adrs(addr)) {
                        addr = ntohl(addr);
                        if (!LOCAL_IP_ADDR(addr)) {
                                ep->class = EPD_IP;
                                set_ip_epdisc(ep, addr);
                                return 1;
                        }
                }
        }

        return 0;
}
#endif /* HAVE_MULTILINK */

/*
 * epdisc_to_str - make a printable string from an endpoint discriminator.
 */

static char *endp_class_names[] = {
    "null", "local", "IP", "MAC", "magic", "phone"
};

char *
epdisc_to_str(ep)
     struct epdisc *ep;
{
        static char str[MAX_ENDP_LEN*3+8];
        u_char *p = ep->value;
        int i, mask = 0;
        char *q, c, c2;

        if (ep->class == EPD_NULL && ep->length == 0)
                return "null";
        if (ep->class == EPD_IP && ep->length == 4) {
                u_int32_t addr;

                GETLONG(addr, p);
                (void) slprintf(str, sizeof(str), "IP:%I", htonl(addr));
                return str;
        }

        c = ':';
        c2 = '.';
        if (ep->class == EPD_MAC && ep->length == 6)
                c2 = ':';
        else if (ep->class == EPD_MAGIC && (ep->length % 4) == 0)
                mask = 3;
        q = str;
        if (ep->class <= EPD_PHONENUM)
                q += slprintf(q, sizeof(str)-1, "%s",
                              endp_class_names[ep->class]);
        else
                q += slprintf(q, sizeof(str)-1, "%d", ep->class);
        c = ':';
        for (i = 0; i < ep->length && i < MAX_ENDP_LEN; ++i) {
                if ((i & mask) == 0) {
                        *q++ = c;
                        c = c2;
                }
                q += slprintf(q, str + sizeof(str) - q, "%.2x", ep->value[i]);
        }
        return str;
}

static int hexc_val(int c)
{
        if (c >= 'a')
                return c - 'a' + 10;
        if (c >= 'A')
                return c - 'A' + 10;
        return c - '0';
}

int
str_to_epdisc(ep, str)
     struct epdisc *ep;
     char *str;
{
        int i, l;
        char *p, *endp;

        for (i = EPD_NULL; i <= EPD_PHONENUM; ++i) {
                int sl = strlen(endp_class_names[i]);
                if (strncasecmp(str, endp_class_names[i], sl) == 0) {
                        str += sl;
                        break;
                }
        }
        if (i > EPD_PHONENUM) {
                /* not a class name, try a decimal class number */
                i = strtol(str, &endp, 10);
                if (endp == str) {
                        option_error("cannot parse endpoint class in \"%s\"",
                            str);
                        return 0;       /* can't parse class number */
                }
                str = endp;
        }
        ep->class = i;
        if (*str == 0) {
                ep->length = 0;
                return 1;
        }
        if (*str != ':' && *str != '.') {
                option_error("invalid class/value separator '%c'", *str);
                return 0;
        }
        ++str;

        if (i == EPD_IP) {
                u_int32_t addr;
                i = parse_dotted_ip(str, &addr);
                if (i == 0 || str[i] != 0)
                        return 0;
                set_ip_epdisc(ep, addr);
                dbglog("str_to_epdisc -> %s", epdisc_to_str(ep));
                return 1;
        }
        if (i == EPD_MAC &&
            get_if_hwaddr(ep->value, sizeof(ep->value), str) >= 0) {
                ep->length = 6;
                dbglog("str_to_epdisc -> %s", epdisc_to_str(ep));
                return 1;
        }

        p = str;
        for (l = 0; l < MAX_ENDP_LEN; ++l) {
                if (*str == 0)
                        break;
                if (p <= str)
                        for (p = str; isxdigit(*p); ++p)
                                ;
                i = p - str;
                if (i == 0) {
                        option_error("no valid hex digits in \"%s\"", str);
                        return 0;
                }
                ep->value[l] = hexc_val(*str++);
                if ((i & 1) == 0)
                        ep->value[l] = (ep->value[l] << 4) + hexc_val(*str++);
                if (*str == ':' || *str == '.')
                        ++str;
        }
        if (*str != 0) {
                option_error("too many bytes in value; max is %d",
                    MAX_ENDP_LEN);
                return 0;
        }
        if (ep->class == EPD_MAC && l != 6) {
                option_error("bad endpoint; MAC address must have 6 bytes");
                return 0;
        }
        ep->length = l;
        dbglog("str_to_epdisc -> %s", epdisc_to_str(ep));
        return 1;
}