/*
 * $NetBSD: util.c,v 1.4 2000/08/03 00:04:30 fvdl Exp $
 */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Frank van der Linden.
 *
 * 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. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <net/if.h>
#include <netinet/in.h>
#include <ifaddrs.h>
#include <sys/poll.h>
#include <rpc/rpc.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <netconfig.h>
#include <stdio.h>
#include <arpa/inet.h>

#include "rpcbind.h"

static struct sockaddr_in *local_in4;
#ifdef INET6
static struct sockaddr_in6 *local_in6;
#endif

static int bitmaskcmp(struct sockaddr *, struct sockaddr *, struct sockaddr *);

/*
 * For all bits set in "mask", compare the corresponding bits in
 * "dst" and "src", and see if they match. Returns 0 if the addresses
 * match.
 */
static int
bitmaskcmp(struct sockaddr *dst, struct sockaddr *src, struct sockaddr *mask)
{
        int i;
        u_int8_t *p1, *p2, *netmask;
        int bytelen;

        if (dst->sa_family != src->sa_family ||
            dst->sa_family != mask->sa_family)
                return (1);

        switch (dst->sa_family) {
        case AF_INET:
                p1 = (uint8_t*) &SA2SINADDR(dst);
                p2 = (uint8_t*) &SA2SINADDR(src);
                netmask = (uint8_t*) &SA2SINADDR(mask);
                bytelen = sizeof(struct in_addr);
                break;
#ifdef INET6
        case AF_INET6:
                p1 = (uint8_t*) &SA2SIN6ADDR(dst);
                p2 = (uint8_t*) &SA2SIN6ADDR(src);
                netmask = (uint8_t*) &SA2SIN6ADDR(mask);
                bytelen = sizeof(struct in6_addr);
                break;
#endif
        default:
                return (1);
        }

        for (i = 0; i < bytelen; i++)
                if ((p1[i] & netmask[i]) != (p2[i] & netmask[i]))
                        return (1);
        return (0);
}

/*
 * Find a server address that can be used by `caller' to contact
 * the local service specified by `serv_uaddr'. If `contct_uaddr' is
 * non-NULL, it is used instead of `caller' as a hint suggesting
 * the best address (e.g. the `r_addr' field of an rpc, which
 * contains the rpcbind server address that the caller used).
 *
 * Returns the best server address as a malloc'd "universal address"
 * string which should be freed by the caller. On error, returns NULL.
 */
char *
addrmerge(struct netbuf *caller, const char *serv_uaddr,
    const char *contct_uaddr, const char *netid)
{
        struct ifaddrs *ifap, *ifp = NULL, *bestif;
        struct netbuf *serv_nbp = NULL, *hint_nbp = NULL, tbuf;
        struct sockaddr *caller_sa, *hint_sa, *ifsa, *ifmasksa, *serv_sa;
        struct sockaddr_storage ss;
        struct netconfig *nconf;
        char *caller_uaddr = NULL;
#ifdef ND_DEBUG
        const char *hint_uaddr = NULL;
#endif
        char *ret = NULL;
        int bestif_goodness;

#ifdef ND_DEBUG
        if (debugging)
                fprintf(stderr, "addrmerge(caller, %s, %s, %s\n", serv_uaddr,
                    contct_uaddr == NULL ? "NULL" : contct_uaddr, netid);
#endif
        caller_sa = caller->buf;
        if ((nconf = rpcbind_get_conf(netid)) == NULL)
                goto freeit;
        if ((caller_uaddr = taddr2uaddr(nconf, caller)) == NULL)
                goto freeit;

        /*
         * Use `contct_uaddr' as the hint if non-NULL, but ignore it if its
         * address family is different from that of the caller.
         */
        hint_sa = NULL;
        if (contct_uaddr != NULL) {
#ifdef ND_DEBUG
                hint_uaddr = contct_uaddr;
#endif
                if ((hint_nbp = uaddr2taddr(nconf, contct_uaddr)) == NULL)
                        goto freeit;
                hint_sa = hint_nbp->buf;
        }
        if (hint_sa == NULL || hint_sa->sa_family != caller_sa->sa_family) {
#ifdef ND_DEBUG
                hint_uaddr = caller_uaddr;
#endif
                hint_sa = caller->buf;
        }

#ifdef ND_DEBUG
        if (debugging)
                fprintf(stderr, "addrmerge: hint %s\n", hint_uaddr);
#endif
        /* Local caller, just return the server address. */
        if (strncmp(caller_uaddr, "0.0.0.0.", 8) == 0 ||
            strncmp(caller_uaddr, "::.", 3) == 0 || caller_uaddr[0] == '/') {
                ret = strdup(serv_uaddr);
                goto freeit;
        }

        if (getifaddrs(&ifp) < 0)
                goto freeit;

        /*
         * Loop through all interface addresses.  We are listening to an address
         * if any of the following are true:
         * a) It's a loopback address
         * b) It was specified with the -h command line option
         * c) There were no -h command line options.
         *
         * Among addresses on which we are listening, choose in order of
         * preference an address that is:
         *
         * a) Equal to the hint
         * b) A link local address with the same scope ID as the client's
         *    address, if the client's address is also link local
         * c) An address on the same subnet as the client's address
         * d) A non-localhost, non-p2p address
         * e) Any usable address
         */
        bestif = NULL;
        bestif_goodness = 0;
        for (ifap = ifp; ifap != NULL; ifap = ifap->ifa_next) {
                ifsa = ifap->ifa_addr;
                ifmasksa = ifap->ifa_netmask;

                /* Skip addresses where we don't listen */
                if (ifsa == NULL || ifsa->sa_family != hint_sa->sa_family ||
                    !(ifap->ifa_flags & IFF_UP))
                        continue;

                if (!(ifap->ifa_flags & IFF_LOOPBACK) && !listen_addr(ifsa))
                        continue;

                if ((hint_sa->sa_family == AF_INET) &&
                    ((((struct sockaddr_in*)hint_sa)->sin_addr.s_addr == 
                      ((struct sockaddr_in*)ifsa)->sin_addr.s_addr))) {
                        const int goodness = 4;

                        bestif_goodness = goodness;
                        bestif = ifap;
                        goto found;
                }
#ifdef INET6
                if ((hint_sa->sa_family == AF_INET6) &&
                    (0 == memcmp(&((struct sockaddr_in6*)hint_sa)->sin6_addr,
                                 &((struct sockaddr_in6*)ifsa)->sin6_addr,
                                 sizeof(struct in6_addr))) &&
                    (((struct sockaddr_in6*)hint_sa)->sin6_scope_id ==
                    (((struct sockaddr_in6*)ifsa)->sin6_scope_id))) {
                        const int goodness = 4;

                        bestif_goodness = goodness;
                        bestif = ifap;
                        goto found;
                }
                if (hint_sa->sa_family == AF_INET6) {
                        /*
                         * For v6 link local addresses, if the caller is on
                         * a link-local address then use the scope id to see
                         * which one.
                         */
                        if (IN6_IS_ADDR_LINKLOCAL(&SA2SIN6ADDR(ifsa))) {
                                if (IN6_IS_ADDR_LINKLOCAL(&SA2SIN6ADDR(caller_sa)) &&
                                    IN6_IS_ADDR_LINKLOCAL(&SA2SIN6ADDR(hint_sa)) &&
                                    (SA2SIN6(ifsa)->sin6_scope_id ==
                                     SA2SIN6(caller_sa)->sin6_scope_id)) {
                                        const int goodness = 3;

                                        if (bestif_goodness < goodness) {
                                                bestif = ifap;
                                                bestif_goodness = goodness;
                                        }
                                } else {
                                        continue;
                                }
                        }
                }
#endif /* INET6 */
                if (0 == bitmaskcmp(hint_sa, ifsa, ifmasksa)) {
                        const int goodness = 2;

                        if (bestif_goodness < goodness) {
                                bestif = ifap;
                                bestif_goodness = goodness;
                        }
                }
                if (!(ifap->ifa_flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) {
                        const int goodness = 1;

                        if (bestif_goodness < goodness) {
                                bestif = ifap;
                                bestif_goodness = goodness;
                        }
                }
                if (bestif == NULL)
                        bestif = ifap;
        }
        if (bestif == NULL)
                goto freeit;

found:
        /*
         * Construct the new address using the address from
         * `bestif', and the port number from `serv_uaddr'.
         */
        serv_nbp = uaddr2taddr(nconf, serv_uaddr);
        if (serv_nbp == NULL)
                goto freeit;
        serv_sa = serv_nbp->buf;

        memcpy(&ss, bestif->ifa_addr, bestif->ifa_addr->sa_len);
        switch (ss.ss_family) {
        case AF_INET:
                SA2SIN(&ss)->sin_port = SA2SIN(serv_sa)->sin_port;
                break;
#ifdef INET6
        case AF_INET6:
                SA2SIN6(&ss)->sin6_port = SA2SIN6(serv_sa)->sin6_port;
                break;
#endif
        }
        tbuf.len = ss.ss_len;
        tbuf.maxlen = sizeof(ss);
        tbuf.buf = &ss;
        ret = taddr2uaddr(nconf, &tbuf);

freeit:
        free(caller_uaddr);
        if (hint_nbp != NULL) {
                free(hint_nbp->buf);
                free(hint_nbp);
        }
        if (serv_nbp != NULL) {
                free(serv_nbp->buf);
                free(serv_nbp);
        }
        if (ifp != NULL)
                freeifaddrs(ifp);

#ifdef ND_DEBUG
        if (debugging)
                fprintf(stderr, "addrmerge: returning %s\n", ret);
#endif
        return ret;
}

void
network_init(void)
{
#ifdef INET6
        struct ifaddrs *ifap, *ifp;
        struct ipv6_mreq mreq6;
        unsigned int ifindex;
        int s;
#endif
        int ecode;
        struct addrinfo hints, *res;

        memset(&hints, 0, sizeof hints);
        hints.ai_family = AF_INET;
        if ((ecode = getaddrinfo(NULL, "sunrpc", &hints, &res))) {
                if (debugging)
                        fprintf(stderr, "can't get local ip4 address: %s\n",
                            gai_strerror(ecode));
        } else {
                local_in4 = (struct sockaddr_in *)malloc(sizeof *local_in4);
                if (local_in4 == NULL) {
                        if (debugging)
                                fprintf(stderr, "can't alloc local ip4 addr\n");
                        exit(1);
                }
                memcpy(local_in4, res->ai_addr, sizeof *local_in4);
                freeaddrinfo(res);
        }

#ifdef INET6
        hints.ai_family = AF_INET6;
        if ((ecode = getaddrinfo(NULL, "sunrpc", &hints, &res))) {
                if (debugging)
                        fprintf(stderr, "can't get local ip6 address: %s\n",
                            gai_strerror(ecode));
        } else {
                local_in6 = (struct sockaddr_in6 *)malloc(sizeof *local_in6);
                if (local_in6 == NULL) {
                        if (debugging)
                                fprintf(stderr, "can't alloc local ip6 addr\n");
                        exit(1);
                }
                memcpy(local_in6, res->ai_addr, sizeof *local_in6);
                freeaddrinfo(res);
        }

        /*
         * Now join the RPC ipv6 multicast group on all interfaces.
         */
        if (getifaddrs(&ifp) < 0)
                return;

        mreq6.ipv6mr_interface = 0;
        inet_pton(AF_INET6, RPCB_MULTICAST_ADDR, &mreq6.ipv6mr_multiaddr);

        s = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
        if (s == -1) {
                if (debugging)
                        fprintf(stderr, "couldn't create ip6 socket");
                goto done_inet6;
        }

        /*
         * Loop through all interfaces. For each IPv6 multicast-capable
         * interface, join the RPC multicast group on that interface.
         */
        for (ifap = ifp; ifap != NULL; ifap = ifap->ifa_next) {
                if (ifap->ifa_addr->sa_family != AF_INET6 ||
                    !(ifap->ifa_flags & IFF_MULTICAST))
                        continue;
                ifindex = if_nametoindex(ifap->ifa_name);
                if (ifindex == mreq6.ipv6mr_interface)
                        /*
                         * Already did this one.
                         */
                        continue;
                mreq6.ipv6mr_interface = ifindex;
                if (setsockopt(s, IPPROTO_IPV6, IPV6_JOIN_GROUP, &mreq6,
                    sizeof mreq6) < 0)
                        if (debugging)
                                perror("setsockopt v6 multicast");
        }
done_inet6:
        freeifaddrs(ifp);
#endif

        /* close(s); */
}

struct sockaddr *
local_sa(int af)
{
        switch (af) {
        case AF_INET:
                return (struct sockaddr *)local_in4;
#ifdef INET6
        case AF_INET6:
                return (struct sockaddr *)local_in6;
#endif
        default:
                return NULL;
        }
}