multilink.c

/*
 * multilink.c - support routines for multilink.
 *
 * Copyright (c) 2000-2002 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 && defined(HAVE_MULTILINK) /* don't build if not configured for use in lwipopts.h */

/* Multilink support
 *
 * Multilink uses Samba TDB (Trivial Database Library), which
 * we cannot port, because it needs a filesystem.
 *
 * We have to choose between doing a memory-shared TDB-clone,
 * or dropping multilink support at all.
 */

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

#include "netif/ppp/ppp_impl.h"

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

bool endpoint_specified;    /* user gave explicit endpoint discriminator */
char *bundle_id;        /* identifier for our bundle */
char *blinks_id;        /* key for the list of links */
bool doing_multilink;       /* multilink was enabled and agreed to */
bool multilink_master;      /* we own the multilink bundle */

extern TDB_CONTEXT *pppdb;
extern char db_key[];

static void make_bundle_links (int append);
static void remove_bundle_link (void);
static void iterate_bundle_links (void (*func) (char *));

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

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

#define LOCAL_IP_ADDR(addr)                       \
    (((addr) & 0xff000000) == 0x0a000000        /* 10.x.x.x */    \
     || ((addr) & 0xfff00000) == 0xac100000     /* 172.16.x.x */  \
     || ((addr) & 0xffff0000) == 0xc0a80000)    /* 192.168.x.x */

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

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

    doing_multilink = 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);
    }
}

/*
 * 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];
    lcp_options *ao = &lcp_allowoptions[0];
    int unit, pppd_pid;
    int l, mtu;
    char *p;
    TDB_DATA key, pid, rec;

    if (doing_multilink) {
        /* have previously joined a bundle */
        if (!go->neg_mrru || !ho->neg_mrru) {
            notice("oops, didn't get multilink on renegotiation");
            lcp_close(pcb, "multilink required");
            return 0;
        }
        /* XXX should check the peer_authname and ho->endpoint
           are the same as previously */
        return 0;
    }

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

    doing_multilink = 1;

    /*
     * 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.
     */
    l = 4 * strlen(peer_authname) + 10;
    if (ho->neg_endpoint)
        l += 3 * ho->endpoint.length + 8;
    if (bundle_name)
        l += 3 * strlen(bundle_name) + 2;
    bundle_id = malloc(l);
    if (bundle_id == 0)
        novm("bundle identifier");

    p = bundle_id;
    p += slprintf(p, l-1, "BUNDLE=\"%q\"", peer_authname);
    if (ho->neg_endpoint || bundle_name)
        *p++ = '/';
    if (ho->neg_endpoint)
        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);

    /* Make the key for the list of links belonging to the bundle */
    l = p - bundle_id;
    blinks_id = malloc(l + 7);
    if (blinks_id == NULL)
        novm("bundle links key");
    slprintf(blinks_id, l + 7, "BUNDLE_LINKS=%s", bundle_id + 7);

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

    /*
     * Check if the bundle ID is already in the database.
     */
    unit = -1;
    lock_db();
    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 && rec.dsize > 0) {
            /* make sure the string is null-terminated */
            rec.dptr[rec.dsize-1] = 0;
            /* 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);
            make_bundle_links(1);
            unlock_db();
            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);
    netif_set_mtu(pcb, mtu);
    script_setenv("BUNDLE", bundle_id + 7, 1);
    make_bundle_links(pcb);
    unlock_db();
    info("New bundle %s created", ifname);
    multilink_master = 1;
    return 0;
}

void mp_exit_bundle()
{
    lock_db();
    remove_bundle_link();
    unlock_db();
}

static void sendhup(char *str)
{
    int pid;

    if (parse_num(str, "PPPD_PID=", &pid) && pid != getpid()) {
        if (debug)
            dbglog("sending SIGHUP to process %d", pid);
        kill(pid, SIGHUP);
    }
}

void mp_bundle_terminated()
{
    TDB_DATA key;

    bundle_terminating = 1;
    upper_layers_down(pcb);
    notice("Connection terminated.");
#if PPP_STATS_SUPPORT
    print_link_stats();
#endif /* PPP_STATS_SUPPORT */
    if (!demand) {
        remove_pidfiles();
        script_unsetenv("IFNAME");
    }

    lock_db();
    destroy_bundle();
    iterate_bundle_links(sendhup);
    key.dptr = blinks_id;
    key.dsize = strlen(blinks_id);
    tdb_delete(pppdb, key);
    unlock_db();

    new_phase(PPP_PHASE_DEAD);

    doing_multilink = 0;
    multilink_master = 0;
}

static void make_bundle_links(int append)
{
    TDB_DATA key, rec;
    char *p;
    char entry[32];
    int l;

    key.dptr = blinks_id;
    key.dsize = strlen(blinks_id);
    slprintf(entry, sizeof(entry), "%s;", db_key);
    p = entry;
    if (append) {
        rec = tdb_fetch(pppdb, key);
        if (rec.dptr != NULL && rec.dsize > 0) {
            rec.dptr[rec.dsize-1] = 0;
            if (strstr(rec.dptr, db_key) != NULL) {
                /* already in there? strange */
                warn("link entry already exists in tdb");
                return;
            }
            l = rec.dsize + strlen(entry);
            p = malloc(l);
            if (p == NULL)
                novm("bundle link list");
            slprintf(p, l, "%s%s", rec.dptr, entry);
        } else {
            warn("bundle link list not found");
        }
        if (rec.dptr != NULL)
            free(rec.dptr);
    }
    rec.dptr = p;
    rec.dsize = strlen(p) + 1;
    if (tdb_store(pppdb, key, rec, TDB_REPLACE))
        error("couldn't %s bundle link list",
              append? "update": "create");
    if (p != entry)
        free(p);
}

static void remove_bundle_link()
{
    TDB_DATA key, rec;
    char entry[32];
    char *p, *q;
    int l;

    key.dptr = blinks_id;
    key.dsize = strlen(blinks_id);
    slprintf(entry, sizeof(entry), "%s;", db_key);

    rec = tdb_fetch(pppdb, key);
    if (rec.dptr == NULL || rec.dsize <= 0) {
        if (rec.dptr != NULL)
            free(rec.dptr);
        return;
    }
    rec.dptr[rec.dsize-1] = 0;
    p = strstr(rec.dptr, entry);
    if (p != NULL) {
        q = p + strlen(entry);
        l = strlen(q) + 1;
        memmove(p, q, l);
        rec.dsize = p - rec.dptr + l;
        if (tdb_store(pppdb, key, rec, TDB_REPLACE))
            error("couldn't update bundle link list (removal)");
    }
    free(rec.dptr);
}

static void iterate_bundle_links(void (*func)(char *))
{
    TDB_DATA key, rec, pp;
    char *p, *q;

    key.dptr = blinks_id;
    key.dsize = strlen(blinks_id);
    rec = tdb_fetch(pppdb, key);
    if (rec.dptr == NULL || rec.dsize <= 0) {
        error("bundle link list not found (iterating list)");
        if (rec.dptr != NULL)
            free(rec.dptr);
        return;
    }
    p = rec.dptr;
    p[rec.dsize-1] = 0;
    while ((q = strchr(p, ';')) != NULL) {
        *q = 0;
        key.dptr = p;
        key.dsize = q - p;
        pp = tdb_fetch(pppdb, key);
        if (pp.dptr != NULL && pp.dsize > 0) {
            pp.dptr[pp.dsize-1] = 0;
            func(pp.dptr);
        }
        if (pp.dptr != NULL)
            free(pp.dptr);
        p = q + 1;
    }
    free(rec.dptr);
}

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;

    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;
{
    char *p;
    struct hostent *hp;
    u32_t addr;

    /* First try for an ethernet MAC address */
    p = get_first_ethernet();
    if (p != 0 && get_if_hwaddr(ep->value, p) >= 0) {
        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 = *(u32_t *)hp->h_addr;
        if (!bad_ip_adrs(addr)) {
            addr = lwip_ntohl(addr);
            if (!LOCAL_IP_ADDR(addr)) {
                ep->class = EPD_IP;
                set_ip_epdisc(ep, addr);
                return 1;
            }
        }
    }

    return 0;
}

/*
 * 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) {
        u32_t addr;

        GETLONG(addr, p);
        slprintf(str, sizeof(str), "IP:%I", lwip_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)
            return 0;   /* can't parse class number */
        str = endp;
    }
    ep->class = i;
    if (*str == 0) {
        ep->length = 0;
        return 1;
    }
    if (*str != ':' && *str != '.')
        return 0;
    ++str;

    if (i == EPD_IP) {
        u32_t addr;
        i = parse_dotted_ip(str, &addr);
        if (i == 0 || str[i] != 0)
            return 0;
        set_ip_epdisc(ep, addr);
        return 1;
    }
    if (i == EPD_MAC && get_if_hwaddr(ep->value, str) >= 0) {
        ep->length = 6;
        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)
            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 || (ep->class == EPD_MAC && l != 6))
        return 0;
    ep->length = l;
    return 1;
}

#endif /* PPP_SUPPORT && HAVE_MULTILINK */