text: /*
   * $NetBSD: util.c,v 1.4 2000/08/03 00:04:30 fvdl Exp $
   * $FreeBSD: releng/11.0/usr.sbin/rpcbind/util.c 300973 2016-05-29 20:28:01Z ngie $
   */
  
  /*-
   * 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 <errno.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.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 `clnt_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 *clnt_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,
  		    clnt_uaddr == NULL ? "NULL" : clnt_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 `clnt_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 (clnt_uaddr != NULL) {
  #ifdef ND_DEBUG
  		hint_uaddr = clnt_uaddr;
  #endif
  		if ((hint_nbp = uaddr2taddr(nconf, clnt_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)) &&
  			    IN6_IS_ADDR_LINKLOCAL(&SA2SIN6ADDR(caller_sa)) &&
  			    IN6_IS_ADDR_LINKLOCAL(&SA2SIN6ADDR(hint_sa))) {
  				if (SA2SIN6(ifsa)->sin6_scope_id ==
  				    SA2SIN6(caller_sa)->sin6_scope_id) {
  					const int goodness = 3;
  
  					if (bestif_goodness < goodness) {
  						bestif = ifap;
  						bestif_goodness = goodness;
  					}
  				}
  			}
  		}
  #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;
  	}
  }
  