text: /*
   * Copyright (c) 2000-2018 Apple Inc. All rights reserved.
   *
   * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   *
   * This file contains Original Code and/or Modifications of Original Code
   * as defined in and that are subject to the Apple Public Source License
   * Version 2.0 (the 'License'). You may not use this file except in
   * compliance with the License. The rights granted to you under the License
   * may not be used to create, or enable the creation or redistribution of,
   * unlawful or unlicensed copies of an Apple operating system, or to
   * circumvent, violate, or enable the circumvention or violation of, any
   * terms of an Apple operating system software license agreement.
   *
   * Please obtain a copy of the License at
   * http://www.opensource.apple.com/apsl/ and read it before using this file.
   *
   * The Original Code and all software distributed under the License are
   * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
   * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
   * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
   * Please see the License for the specific language governing rights and
   * limitations under the License.
   *
   * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
   */
  /*
   * Copyright (c) 1982, 1986, 1988, 1993
   *	The Regents of the University of California.  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. 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.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This product includes software developed by the University of
   *	California, Berkeley and its contributors.
   * 4. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
   *
   *	@(#)ip_icmp.c	8.2 (Berkeley) 1/4/94
   */
  /*
   * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce
   * support for mandatory and extensible security protections.  This notice
   * is included in support of clause 2.2 (b) of the Apple Public License,
   * Version 2.0.
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/mbuf.h>
  #include <sys/mcache.h>
  #include <sys/protosw.h>
  #include <sys/socket.h>
  #include <sys/time.h>
  #include <sys/kernel.h>
  #include <sys/sysctl.h>
  
  #include <machine/endian.h>
  
  #include <net/if.h>
  #include <net/route.h>
  
  #define _IP_VHL
  #include <netinet/in.h>
  #include <netinet/in_systm.h>
  #include <netinet/in_var.h>
  #include <netinet/ip.h>
  #include <netinet/ip_icmp.h>
  #include <netinet/ip_var.h>
  #include <netinet/icmp_var.h>
  #include <netinet/tcp.h>
  #include <netinet/tcp_fsm.h>
  #include <netinet/tcp_seq.h>
  #include <netinet/tcp_timer.h>
  #include <netinet/tcp_var.h>
  #include <netinet/tcpip.h>
  
  #if IPSEC
  #include <netinet6/ipsec.h>
  #include <netkey/key.h>
  #endif
  
  #if NECP
  #include <net/necp.h>
  #endif /* NECP */
  
  /* XXX This one should go in sys/mbuf.h. It is used to avoid that
   * a firewall-generated packet loops forever through the firewall.
   */
  #ifndef M_SKIP_FIREWALL
  #define M_SKIP_FIREWALL         0x4000
  #endif
  
  #if CONFIG_MACF_NET
  #include <security/mac_framework.h>
  #endif /* MAC_NET */
  
  
  /*
   * ICMP routines: error generation, receive packet processing, and
   * routines to turnaround packets back to the originator, and
   * host table maintenance routines.
   */
  
  struct  icmpstat icmpstat;
  SYSCTL_STRUCT(_net_inet_icmp, ICMPCTL_STATS, stats,
      CTLFLAG_RD | CTLFLAG_LOCKED,
      &icmpstat, icmpstat, "");
  
  static int      icmpmaskrepl = 0;
  SYSCTL_INT(_net_inet_icmp, ICMPCTL_MASKREPL, maskrepl,
      CTLFLAG_RW | CTLFLAG_LOCKED,
      &icmpmaskrepl, 0, "");
  
  static int      icmptimestamp = 0;
  SYSCTL_INT(_net_inet_icmp, ICMPCTL_TIMESTAMP, timestamp,
      CTLFLAG_RW | CTLFLAG_LOCKED,
      &icmptimestamp, 0, "");
  
  static int      drop_redirect = 1;
  SYSCTL_INT(_net_inet_icmp, OID_AUTO, drop_redirect,
      CTLFLAG_RW | CTLFLAG_LOCKED,
      &drop_redirect, 0, "");
  
  static int      log_redirect = 0;
  SYSCTL_INT(_net_inet_icmp, OID_AUTO, log_redirect,
      CTLFLAG_RW | CTLFLAG_LOCKED,
      &log_redirect, 0, "");
  
  const static int icmp_datalen = 8;
  
  #if ICMP_BANDLIM
  
  /* Default values in case CONFIG_ICMP_BANDLIM is not defined in the MASTER file */
  #ifndef CONFIG_ICMP_BANDLIM
  #if !CONFIG_EMBEDDED
  #define CONFIG_ICMP_BANDLIM 250
  #else /* CONFIG_EMBEDDED */
  #define CONFIG_ICMP_BANDLIM 50
  #endif /* CONFIG_EMBEDDED */
  #endif /* CONFIG_ICMP_BANDLIM */
  
  /*
   * ICMP error-response bandwidth limiting sysctl.  If not enabled, sysctl
   *      variable content is -1 and read-only.
   */
  
  static int      icmplim = CONFIG_ICMP_BANDLIM;
  SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RW | CTLFLAG_LOCKED,
      &icmplim, 0, "");
  
  #else /* ICMP_BANDLIM */
  
  static int      icmplim = -1;
  SYSCTL_INT(_net_inet_icmp, ICMPCTL_ICMPLIM, icmplim, CTLFLAG_RD | CTLFLAG_LOCKED,
      &icmplim, 0, "");
  
  #endif /* ICMP_BANDLIM */
  
  /*
   * ICMP broadcast echo sysctl
   */
  
  static int      icmpbmcastecho = 1;
  SYSCTL_INT(_net_inet_icmp, OID_AUTO, bmcastecho, CTLFLAG_RW | CTLFLAG_LOCKED,
      &icmpbmcastecho, 0, "");
  
  #if (DEBUG | DEVELOPMENT)
  static int      icmpprintfs = 0;
  SYSCTL_INT(_net_inet_icmp, OID_AUTO, verbose, CTLFLAG_RW | CTLFLAG_LOCKED,
      &icmpprintfs, 0, "");
  #endif
  
  static void     icmp_reflect(struct mbuf *);
  static void     icmp_send(struct mbuf *, struct mbuf *);
  
  /*
   * Generate an error packet of type error
   * in response to bad packet ip.
   */
  void
  icmp_error(
  	struct mbuf *n,
  	int type,
  	int code,
  	u_int32_t dest,
  	u_int32_t nextmtu)
  {
  	struct ip *oip = NULL;
  	struct ip *nip = NULL;
  	struct icmp *icp = NULL;
  	struct mbuf *m = NULL;
  	u_int32_t oiphlen = 0;
  	u_int32_t icmplen = 0;
  	u_int32_t icmpelen = 0;
  	u_int32_t nlen = 0;
  
  	VERIFY((u_int)type <= ICMP_MAXTYPE);
  	/* Expect 32-bit aligned data pointer on strict-align platforms */
  	MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(n);
  
  	if (type != ICMP_REDIRECT) {
  		icmpstat.icps_error++;
  	}
  	/*
  	 * Don't send error:
  	 *   if not the first fragment of message
  	 *   if original packet was a multicast or broadcast packet
  	 *   if the old packet protocol was ICMP
  	 *   error message, only known informational types.
  	 */
  	if (n->m_flags & (M_BCAST | M_MCAST)) {
  		goto freeit;
  	}
  
  	/*
  	 * Drop if IP header plus ICMP_MINLEN bytes are not contiguous
  	 * in first mbuf.
  	 */
  	if (n->m_len < sizeof(struct ip) + ICMP_MINLEN) {
  		goto freeit;
  	}
  
  	oip = mtod(n, struct ip *);
  	oiphlen = IP_VHL_HL(oip->ip_vhl) << 2;
  	if (n->m_len < oiphlen + ICMP_MINLEN) {
  		goto freeit;
  	}
  
  #if (DEBUG | DEVELOPMENT)
  	if (icmpprintfs > 1) {
  		printf("icmp_error(0x%llx, %x, %d)\n",
  		    (uint64_t)VM_KERNEL_ADDRPERM(oip), type, code);
  	}
  #endif
  
  	if (oip->ip_off & ~(IP_MF | IP_DF)) {
  		goto freeit;
  	}
  
  	if (oip->ip_p == IPPROTO_ICMP && type != ICMP_REDIRECT &&
  	    n->m_len >= oiphlen + ICMP_MINLEN &&
  	    !ICMP_INFOTYPE(((struct icmp *)(void *)((caddr_t)oip + oiphlen))->
  	    icmp_type)) {
  		icmpstat.icps_oldicmp++;
  		goto freeit;
  	}
  
  	/*
  	 * Calculate the length to quote from original packet and prevent
  	 * the ICMP mbuf from overflowing.
  	 * Unfortunatly this is non-trivial since ip_forward()
  	 * sends us truncated packets.
  	 */
  	nlen = m_length(n);
  	if (oip->ip_p == IPPROTO_TCP) {
  		struct tcphdr *th = NULL;
  		u_int16_t tcphlen = 0;
  
  		/*
  		 * If the packet got truncated and TCP header
  		 * is not contained in the packet, send out
  		 * standard reply with only IP header as payload
  		 */
  		if (oiphlen + sizeof(struct tcphdr) > n->m_len &&
  		    n->m_next == NULL) {
  			goto stdreply;
  		}
  
  		/*
  		 * Otherwise, pull up to get IP and TCP headers
  		 * together
  		 */
  		if (n->m_len < (oiphlen + sizeof(struct tcphdr)) &&
  		    (n = m_pullup(n, (oiphlen + sizeof(struct tcphdr)))) == NULL) {
  			goto freeit;
  		}
  
  		/*
  		 * Reinit pointers derived from mbuf data pointer
  		 * as things might have moved around with m_pullup
  		 */
  		oip = mtod(n, struct ip *);
  		th = (struct tcphdr *)(void *)((caddr_t)oip + oiphlen);
  
  		if (th != ((struct tcphdr *)P2ROUNDDOWN(th,
  		    sizeof(u_int32_t)))) {
  			goto freeit;
  		}
  		tcphlen = th->th_off << 2;
  
  		/* Sanity checks */
  		if (tcphlen < sizeof(struct tcphdr)) {
  			goto freeit;
  		}
  		if (oip->ip_len < (oiphlen + tcphlen)) {
  			goto freeit;
  		}
  		if ((oiphlen + tcphlen) > n->m_len && n->m_next == NULL) {
  			goto stdreply;
  		}
  		if (n->m_len < (oiphlen + tcphlen) &&
  		    (n = m_pullup(n, (oiphlen + tcphlen))) == NULL) {
  			goto freeit;
  		}
  
  		/*
  		 * Reinit pointers derived from mbuf data pointer
  		 * as things might have moved around with m_pullup
  		 */
  		oip = mtod(n, struct ip *);
  		th = (struct tcphdr *)(void *)((caddr_t)oip + oiphlen);
  
  		icmpelen = max(tcphlen, min(icmp_datalen,
  		    (oip->ip_len - oiphlen)));
  	} else {
  stdreply:       icmpelen = max(ICMP_MINLEN, min(icmp_datalen,
  		    (oip->ip_len - oiphlen)));
  	}
  
  	icmplen = min(oiphlen + icmpelen, nlen);
  	if (icmplen < sizeof(struct ip)) {
  		goto freeit;
  	}
  
  	/*
  	 * First, formulate icmp message
  	 * Allocate enough space for the IP header, ICMP header
  	 * and the payload (part of the original message to be sent back).
  	 */
  	if (MHLEN > (sizeof(struct ip) + ICMP_MINLEN + icmplen)) {
  		m = m_gethdr(M_DONTWAIT, MT_HEADER);    /* MAC-OK */
  	} else {
  		m = m_getcl(M_DONTWAIT, MT_DATA, M_PKTHDR);
  	}
  
  	if (m == NULL) {
  		goto freeit;
  	}
  
  #if CONFIG_MACF_NET
  	mac_mbuf_label_associate_netlayer(n, m);
  #endif
  	/*
  	 * Further refine the payload length to the space
  	 * remaining in mbuf after including the IP header and ICMP
  	 * header.
  	 */
  	icmplen = min(icmplen, M_TRAILINGSPACE(m) -
  	    sizeof(struct ip) - ICMP_MINLEN);
  	m_align(m, ICMP_MINLEN + icmplen);
  	m->m_len = ICMP_MINLEN + icmplen; /* for ICMP header and data */
  
  	icp = mtod(m, struct icmp *);
  	icmpstat.icps_outhist[type]++;
  	icp->icmp_type = type;
  	if (type == ICMP_REDIRECT) {
  		icp->icmp_gwaddr.s_addr = dest;
  	} else {
  		icp->icmp_void = 0;
  		/*
  		 * The following assignments assume an overlay with the
  		 * zeroed icmp_void field.
  		 */
  		if (type == ICMP_PARAMPROB) {
  			icp->icmp_pptr = code;
  			code = 0;
  		} else if (type == ICMP_UNREACH &&
  		    code == ICMP_UNREACH_NEEDFRAG && nextmtu != 0) {
  			icp->icmp_nextmtu = htons(nextmtu);
  		}
  	}
  
  	icp->icmp_code = code;
  
  	/*
  	 * Copy icmplen worth of content from original
  	 * mbuf (n) to the new packet after ICMP header.
  	 */
  	m_copydata(n, 0, icmplen, (caddr_t)&icp->icmp_ip);
  	nip = &icp->icmp_ip;
  
  	/*
  	 * Convert fields to network representation.
  	 */
  #if BYTE_ORDER != BIG_ENDIAN
  	HTONS(nip->ip_len);
  	HTONS(nip->ip_off);
  #endif
  	/*
  	 * Set up ICMP message mbuf and copy old IP header (without options
  	 * in front of ICMP message.
  	 * If the original mbuf was meant to bypass the firewall, the error
  	 * reply should bypass as well.
  	 */
  	m->m_flags |= n->m_flags & M_SKIP_FIREWALL;
  	m->m_data -= sizeof(struct ip);
  	m->m_len += sizeof(struct ip);
  	m->m_pkthdr.len = m->m_len;
  	m->m_pkthdr.rcvif = n->m_pkthdr.rcvif;
  	nip = mtod(m, struct ip *);
  	bcopy((caddr_t)oip, (caddr_t)nip, sizeof(struct ip));
  	nip->ip_len = m->m_len;
  	nip->ip_vhl = IP_VHL_BORING;
  	nip->ip_p = IPPROTO_ICMP;
  	nip->ip_tos = 0;
  	nip->ip_off = 0;
  	icmp_reflect(m);
  freeit:
  	m_freem(n);
  }
  
  /*
   * Process a received ICMP message.
   */
  void
  icmp_input(struct mbuf *m, int hlen)
  {
  	struct sockaddr_in icmpsrc, icmpdst, icmpgw;
  	struct icmp *icp;
  	struct ip *ip = mtod(m, struct ip *);
  	int icmplen;
  	int i;
  	struct in_ifaddr *ia;
  	void (*ctlfunc)(int, struct sockaddr *, void *, struct ifnet *);
  	int code;
  	boolean_t should_log_redirect = false;
  
  	/* Expect 32-bit aligned data pointer on strict-align platforms */
  	MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
  
  	icmplen = ip->ip_len;
  
  	/*
  	 * Locate icmp structure in mbuf, and check
  	 * that not corrupted and of at least minimum length.
  	 */
  #if (DEBUG | DEVELOPMENT)
  	if (icmpprintfs > 2) {
  		char src_str[MAX_IPv4_STR_LEN];
  		char dst_str[MAX_IPv4_STR_LEN];
  
  		inet_ntop(AF_INET, &ip->ip_src, src_str, sizeof(src_str));
  		inet_ntop(AF_INET, &ip->ip_dst, dst_str, sizeof(dst_str));
  		printf("%s: from %s to %s, len %d\n",
  		    __func__, src_str, dst_str, icmplen);
  	}
  #endif
  	if (icmplen < ICMP_MINLEN) {
  		icmpstat.icps_tooshort++;
  		goto freeit;
  	}
  	i = hlen + min(icmplen, ICMP_ADVLENMIN);
  	if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
  		icmpstat.icps_tooshort++;
  		return;
  	}
  	ip = mtod(m, struct ip *);
  	m->m_len -= hlen;
  	m->m_data += hlen;
  	icp = mtod(m, struct icmp *);
  	if (in_cksum(m, icmplen)) {
  		icmpstat.icps_checksum++;
  		goto freeit;
  	}
  	m->m_len += hlen;
  	m->m_data -= hlen;
  
  #if (DEBUG | DEVELOPMENT)
  	if (icmpprintfs > 2) {
  		printf("icmp_input, type %d code %d\n", icp->icmp_type,
  		    icp->icmp_code);
  	}
  #endif
  
  	/*
  	 * Message type specific processing.
  	 */
  	if (icp->icmp_type > ICMP_MAXTYPE) {
  		goto raw;
  	}
  
  	/* Initialize */
  	bzero(&icmpsrc, sizeof(icmpsrc));
  	icmpsrc.sin_len = sizeof(struct sockaddr_in);
  	icmpsrc.sin_family = AF_INET;
  	bzero(&icmpdst, sizeof(icmpdst));
  	icmpdst.sin_len = sizeof(struct sockaddr_in);
  	icmpdst.sin_family = AF_INET;
  	bzero(&icmpgw, sizeof(icmpgw));
  	icmpgw.sin_len = sizeof(struct sockaddr_in);
  	icmpgw.sin_family = AF_INET;
  
  	icmpstat.icps_inhist[icp->icmp_type]++;
  	code = icp->icmp_code;
  	switch (icp->icmp_type) {
  	case ICMP_UNREACH:
  		switch (code) {
  		case ICMP_UNREACH_NET:
  		case ICMP_UNREACH_HOST:
  		case ICMP_UNREACH_SRCFAIL:
  		case ICMP_UNREACH_NET_UNKNOWN:
  		case ICMP_UNREACH_HOST_UNKNOWN:
  		case ICMP_UNREACH_ISOLATED:
  		case ICMP_UNREACH_TOSNET:
  		case ICMP_UNREACH_TOSHOST:
  		case ICMP_UNREACH_HOST_PRECEDENCE:
  		case ICMP_UNREACH_PRECEDENCE_CUTOFF:
  			code = PRC_UNREACH_NET;
  			break;
  
  		case ICMP_UNREACH_NEEDFRAG:
  			code = PRC_MSGSIZE;
  			break;
  
  		/*
  		 * RFC 1122, Sections 3.2.2.1 and 4.2.3.9.
  		 * Treat subcodes 2,3 as immediate RST
  		 */
  		case ICMP_UNREACH_PROTOCOL:
  		case ICMP_UNREACH_PORT:
  			code = PRC_UNREACH_PORT;
  			break;
  
  		case ICMP_UNREACH_NET_PROHIB:
  		case ICMP_UNREACH_HOST_PROHIB:
  		case ICMP_UNREACH_FILTER_PROHIB:
  			code = PRC_UNREACH_ADMIN_PROHIB;
  			break;
  
  		default:
  			goto badcode;
  		}
  		goto deliver;
  
  	case ICMP_TIMXCEED:
  		if (code > 1) {
  			goto badcode;
  		}
  		code += PRC_TIMXCEED_INTRANS;
  		goto deliver;
  
  	case ICMP_PARAMPROB:
  		if (code > 1) {
  			goto badcode;
  		}
  		code = PRC_PARAMPROB;
  		goto deliver;
  
  	case ICMP_SOURCEQUENCH:
  		if (code) {
  			goto badcode;
  		}
  		code = PRC_QUENCH;
  deliver:
  		/*
  		 * Problem with datagram; advise higher level routines.
  		 */
  		if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp)
  		    || IP_VHL_HL(icp->icmp_ip.ip_vhl) <
  		    (sizeof(struct ip) >> 2) ||
  		    (m = m_pullup(m, hlen + ICMP_ADVLEN(icp))) == NULL) {
  			icmpstat.icps_badlen++;
  			goto freeit;
  		}
  
  		ip = mtod(m, struct ip *);
  		icp = (struct icmp *)(void *)(mtod(m, uint8_t *) + hlen);
  
  #if BYTE_ORDER != BIG_ENDIAN
  		NTOHS(icp->icmp_ip.ip_len);
  #endif
  
  		/* Discard ICMP's in response to multicast packets */
  		if (IN_MULTICAST(ntohl(icp->icmp_ip.ip_dst.s_addr))) {
  			goto badcode;
  		}
  #if (DEBUG | DEVELOPMENT)
  		if (icmpprintfs > 2) {
  			printf("deliver to protocol %d\n",
  			    icp->icmp_ip.ip_p);
  		}
  #endif
  		icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
  
  		/*
  		 * if the packet contains [IPv4 AH TCP], we can't make a
  		 * notification to TCP layer.
  		 */
  		ctlfunc = ip_protox[icp->icmp_ip.ip_p]->pr_ctlinput;
  
  		if (ctlfunc) {
  			LCK_MTX_ASSERT(inet_domain_mutex, LCK_MTX_ASSERT_OWNED);
  
  			lck_mtx_unlock(inet_domain_mutex);
  
  			(*ctlfunc)(code, (struct sockaddr *)&icmpsrc,
  			    (void *)&icp->icmp_ip, m->m_pkthdr.rcvif);
  
  			lck_mtx_lock(inet_domain_mutex);
  		}
  		break;
  
  badcode:
  		icmpstat.icps_badcode++;
  		break;
  
  	case ICMP_ECHO:
  		if ((m->m_flags & (M_MCAST | M_BCAST))) {
  			if (icmpbmcastecho == 0) {
  				icmpstat.icps_bmcastecho++;
  				break;
  			}
  		}
  
  		/*
  		 * rdar://18644769
  		 * Do not reply when the destination is link local multicast or broadcast
  		 * and the source is not from a directly connected subnet
  		 */
  		if ((IN_LOCAL_GROUP(ntohl(ip->ip_dst.s_addr)) ||
  		    in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) &&
  		    in_localaddr(ip->ip_src) == 0) {
  			icmpstat.icps_bmcastecho++;
  #if (DEBUG | DEVELOPMENT)
  			if (icmpprintfs > 0) {
  				char src_str[MAX_IPv4_STR_LEN];
  				char dst_str[MAX_IPv4_STR_LEN];
  
  				inet_ntop(AF_INET, &ip->ip_src, src_str, sizeof(src_str));
  				inet_ntop(AF_INET, &ip->ip_dst, dst_str, sizeof(dst_str));
  				printf("%s: non local (B|M)CAST %s to %s, len %d\n",
  				    __func__, src_str, dst_str, icmplen);
  			}
  #endif
  			break;
  		}
  
  		icp->icmp_type = ICMP_ECHOREPLY;
  #if ICMP_BANDLIM
  		if (badport_bandlim(BANDLIM_ICMP_ECHO) < 0) {
  			goto freeit;
  		} else
  #endif
  		goto reflect;
  
  	case ICMP_TSTAMP:
  		if (icmptimestamp == 0) {
  			break;
  		}
  
  		if (!icmpbmcastecho
  		    && (m->m_flags & (M_MCAST | M_BCAST)) != 0) {
  			icmpstat.icps_bmcasttstamp++;
  			break;
  		}
  		if (icmplen < ICMP_TSLEN) {
  			icmpstat.icps_badlen++;
  			break;
  		}
  		icp->icmp_type = ICMP_TSTAMPREPLY;
  		icp->icmp_rtime = iptime();
  		icp->icmp_ttime = icp->icmp_rtime;      /* bogus, do later! */
  #if ICMP_BANDLIM
  		if (badport_bandlim(BANDLIM_ICMP_TSTAMP) < 0) {
  			goto freeit;
  		} else
  #endif
  		goto reflect;
  
  	case ICMP_MASKREQ:
  		if (icmpmaskrepl == 0) {
  			break;
  		}
  		/*
  		 * We are not able to respond with all ones broadcast
  		 * unless we receive it over a point-to-point interface.
  		 */
  		if (icmplen < ICMP_MASKLEN) {
  			break;
  		}
  		switch (ip->ip_dst.s_addr) {
  		case INADDR_BROADCAST:
  		case INADDR_ANY:
  			icmpdst.sin_addr = ip->ip_src;
  			break;
  
  		default:
  			icmpdst.sin_addr = ip->ip_dst;
  		}
  		ia = (struct in_ifaddr *)ifaof_ifpforaddr(
  			(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
  		if (ia == 0) {
  			break;
  		}
  		IFA_LOCK(&ia->ia_ifa);
  		if (ia->ia_ifp == 0) {
  			IFA_UNLOCK(&ia->ia_ifa);
  			IFA_REMREF(&ia->ia_ifa);
  			ia = NULL;
  			break;
  		}
  		icp->icmp_type = ICMP_MASKREPLY;
  		icp->icmp_mask = ia->ia_sockmask.sin_addr.s_addr;
  		if (ip->ip_src.s_addr == 0) {
  			if (ia->ia_ifp->if_flags & IFF_BROADCAST) {
  				ip->ip_src = satosin(&ia->ia_broadaddr)->sin_addr;
  			} else if (ia->ia_ifp->if_flags & IFF_POINTOPOINT) {
  				ip->ip_src = satosin(&ia->ia_dstaddr)->sin_addr;
  			}
  		}
  		IFA_UNLOCK(&ia->ia_ifa);
  		IFA_REMREF(&ia->ia_ifa);
  reflect:
  		ip->ip_len += hlen;     /* since ip_input deducts this */
  		icmpstat.icps_reflect++;
  		icmpstat.icps_outhist[icp->icmp_type]++;
  		icmp_reflect(m);
  		return;
  
  	case ICMP_REDIRECT:
  		if (drop_redirect) {
  			break;
  		}
  		if (code > 3) {
  			goto badcode;
  		}
  		if (icmplen < ICMP_ADVLENMIN || icmplen < ICMP_ADVLEN(icp) ||
  		    IP_VHL_HL(icp->icmp_ip.ip_vhl) < (sizeof(struct ip) >> 2)) {
  			icmpstat.icps_badlen++;
  			break;
  		}
  
  #if (DEBUG | DEVELOPMENT)
  		should_log_redirect = log_redirect || (icmpprintfs > 0);
  #else
  		should_log_redirect = log_redirect;
  #endif
  		/*
  		 * Short circuit routing redirects to force
  		 * immediate change in the kernel's routing
  		 * tables.  The message is also handed to anyone
  		 * listening on a raw socket (e.g. the routing
  		 * daemon for use in updating its tables).
  		 */
  		icmpgw.sin_addr = ip->ip_src;
  		icmpdst.sin_addr = icp->icmp_gwaddr;
  
  		if (should_log_redirect) {
  			char src_str[MAX_IPv4_STR_LEN];
  			char dst_str[MAX_IPv4_STR_LEN];
  			char gw_str[MAX_IPv4_STR_LEN];
  
  			inet_ntop(AF_INET, &ip->ip_src, src_str, sizeof(src_str));
  			inet_ntop(AF_INET, &icp->icmp_ip.ip_dst, dst_str, sizeof(dst_str));
  			inet_ntop(AF_INET, &icp->icmp_gwaddr, gw_str, sizeof(gw_str));
  			printf("%s: redirect dst %s to %s from %s\n", __func__,
  			    dst_str, gw_str, src_str);
  		}
  		icmpsrc.sin_addr = icp->icmp_ip.ip_dst;
  		rtredirect(m->m_pkthdr.rcvif, (struct sockaddr *)&icmpsrc,
  		    (struct sockaddr *)&icmpdst, NULL, RTF_GATEWAY | RTF_HOST,
  		    (struct sockaddr *)&icmpgw, NULL);
  		pfctlinput(PRC_REDIRECT_HOST, (struct sockaddr *)&icmpsrc);
  #if IPSEC
  		key_sa_routechange((struct sockaddr *)&icmpsrc);
  #endif
  		break;
  
  	/*
  	 * No kernel processing for the following;
  	 * just fall through to send to raw listener.
  	 */
  	case ICMP_ECHOREPLY:
  	case ICMP_ROUTERADVERT:
  	case ICMP_ROUTERSOLICIT:
  	case ICMP_TSTAMPREPLY:
  	case ICMP_IREQREPLY:
  	case ICMP_MASKREPLY:
  	default:
  		break;
  	}
  
  raw:
  	rip_input(m, hlen);
  	return;
  
  freeit:
  	m_freem(m);
  }
  
  /*
   * Reflect the ip packet back to the source
   */
  static void
  icmp_reflect(struct mbuf *m)
  {
  	struct ip *ip = mtod(m, struct ip *);
  	struct sockaddr_in icmpdst;
  	struct in_ifaddr *ia;
  	struct in_addr t;
  	struct mbuf *opts = NULL;
  	int optlen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof(struct ip);
  
  	if (!in_canforward(ip->ip_src) &&
  	    ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) !=
  	    (IN_LOOPBACKNET << IN_CLASSA_NSHIFT))) {
  		m_freem(m);     /* Bad return address */
  		goto done;      /* Ip_output() will check for broadcast */
  	}
  	t = ip->ip_dst;
  	ip->ip_dst = ip->ip_src;
  	/*
  	 * If the incoming packet was addressed directly to us,
  	 * use dst as the src for the reply.  Otherwise (broadcast
  	 * or anonymous), use the address which corresponds
  	 * to the incoming interface.
  	 */
  	lck_rw_lock_shared(in_ifaddr_rwlock);
  	TAILQ_FOREACH(ia, INADDR_HASH(t.s_addr), ia_hash) {
  		IFA_LOCK(&ia->ia_ifa);
  		if (t.s_addr == IA_SIN(ia)->sin_addr.s_addr) {
  			IFA_ADDREF_LOCKED(&ia->ia_ifa);
  			IFA_UNLOCK(&ia->ia_ifa);
  			goto match;
  		}
  		IFA_UNLOCK(&ia->ia_ifa);
  	}
  	/*
  	 * Slow path; check for broadcast addresses.  Find a source
  	 * IP address to use when replying to the broadcast request;
  	 * let IP handle the source interface selection work.
  	 */
  	for (ia = in_ifaddrhead.tqh_first; ia; ia = ia->ia_link.tqe_next) {
  		IFA_LOCK(&ia->ia_ifa);
  		if (ia->ia_ifp && (ia->ia_ifp->if_flags & IFF_BROADCAST) &&
  		    t.s_addr == satosin(&ia->ia_broadaddr)->sin_addr.s_addr) {
  			IFA_ADDREF_LOCKED(&ia->ia_ifa);
  			IFA_UNLOCK(&ia->ia_ifa);
  			break;
  		}
  		IFA_UNLOCK(&ia->ia_ifa);
  	}
  match:
  	lck_rw_done(in_ifaddr_rwlock);
  
  	/* Initialize */
  	bzero(&icmpdst, sizeof(icmpdst));
  	icmpdst.sin_len = sizeof(struct sockaddr_in);
  	icmpdst.sin_family = AF_INET;
  	icmpdst.sin_addr = t;
  	if ((ia == (struct in_ifaddr *)0) && m->m_pkthdr.rcvif) {
  		ia = (struct in_ifaddr *)ifaof_ifpforaddr(
  			(struct sockaddr *)&icmpdst, m->m_pkthdr.rcvif);
  	}
  	/*
  	 * The following happens if the packet was not addressed to us,
  	 * and was received on an interface with no IP address.
  	 */
  	if (ia == (struct in_ifaddr *)0) {
  		lck_rw_lock_shared(in_ifaddr_rwlock);
  		ia = in_ifaddrhead.tqh_first;
  		if (ia == (struct in_ifaddr *)0) {/* no address yet, bail out */
  			lck_rw_done(in_ifaddr_rwlock);
  			m_freem(m);
  			goto done;
  		}
  		IFA_ADDREF(&ia->ia_ifa);
  		lck_rw_done(in_ifaddr_rwlock);
  	}
  #if CONFIG_MACF_NET
  	mac_netinet_icmp_reply(m);
  #endif
  	IFA_LOCK_SPIN(&ia->ia_ifa);
  	t = IA_SIN(ia)->sin_addr;
  	IFA_UNLOCK(&ia->ia_ifa);
  	ip->ip_src = t;
  	ip->ip_ttl = ip_defttl;
  	IFA_REMREF(&ia->ia_ifa);
  	ia = NULL;
  
  	if (optlen > 0) {
  		u_char *cp;
  		int opt, cnt;
  		u_int len;
  
  		/*
  		 * Retrieve any source routing from the incoming packet;
  		 * add on any record-route or timestamp options.
  		 */
  		cp = (u_char *) (ip + 1);
  		if ((opts = ip_srcroute()) == 0 &&
  		    (opts = m_gethdr(M_DONTWAIT, MT_HEADER))) { /* MAC-OK */
  			opts->m_len = sizeof(struct in_addr);
  			mtod(opts, struct in_addr *)->s_addr = 0;
  		}
  		if (opts) {
  #if (DEBUG | DEVELOPMENT)
  			if (icmpprintfs > 1) {
  				printf("icmp_reflect optlen %d rt %d => ",
  				    optlen, opts->m_len);
  			}
  #endif
  			for (cnt = optlen; cnt > 0; cnt -= len, cp += len) {
  				opt = cp[IPOPT_OPTVAL];
  				if (opt == IPOPT_EOL) {
  					break;
  				}
  				if (opt == IPOPT_NOP) {
  					len = 1;
  				} else {
  					if (cnt < IPOPT_OLEN + sizeof(*cp)) {
  						break;
  					}
  					len = cp[IPOPT_OLEN];
  					if (len < IPOPT_OLEN + sizeof(*cp) ||
  					    len > cnt) {
  						break;
  					}
  				}
  				/*
  				 * Should check for overflow, but it "can't happen"
  				 */
  				if (opt == IPOPT_RR || opt == IPOPT_TS ||
  				    opt == IPOPT_SECURITY) {
  					bcopy((caddr_t)cp,
  					    mtod(opts, caddr_t) + opts->m_len, len);
  					opts->m_len += len;
  				}
  			}
  			/* Terminate & pad, if necessary */
  			cnt = opts->m_len % 4;
  			if (cnt) {
  				for (; cnt < 4; cnt++) {
  					*(mtod(opts, caddr_t) + opts->m_len) =
  					    IPOPT_EOL;
  					opts->m_len++;
  				}
  			}
  #if (DEBUG | DEVELOPMENT)
  			if (icmpprintfs > 1) {
  				printf("%d\n", opts->m_len);
  			}
  #endif
  		}
  		/*
  		 * Now strip out original options by copying rest of first
  		 * mbuf's data back, and adjust the IP length.
  		 */
  		ip->ip_len -= optlen;
  		ip->ip_vhl = IP_VHL_BORING;
  		m->m_len -= optlen;
  		if (m->m_flags & M_PKTHDR) {
  			m->m_pkthdr.len -= optlen;
  		}
  		optlen += sizeof(struct ip);
  		bcopy((caddr_t)ip + optlen, (caddr_t)(ip + 1),
  		    (unsigned)(m->m_len - sizeof(struct ip)));
  	}
  	m->m_flags &= ~(M_BCAST | M_MCAST);
  	icmp_send(m, opts);
  done:
  	if (opts) {
  		(void)m_free(opts);
  	}
  }
  
  /*
   * Send an icmp packet back to the ip level,
   * after supplying a checksum.
   */
  static void
  icmp_send(struct mbuf *m, struct mbuf *opts)
  {
  	struct ip *ip = mtod(m, struct ip *);
  	int hlen;
  	struct icmp *icp;
  	struct route ro;
  	struct ip_out_args ipoa;
  
  	bzero(&ipoa, sizeof(ipoa));
  	ipoa.ipoa_boundif = IFSCOPE_NONE;
  	ipoa.ipoa_flags = IPOAF_SELECT_SRCIF | IPOAF_BOUND_SRCADDR;
  	ipoa.ipoa_sotc = SO_TC_UNSPEC;
  	ipoa.ipoa_netsvctype = _NET_SERVICE_TYPE_UNSPEC;
  
  	if (!(m->m_pkthdr.pkt_flags & PKTF_LOOP) && m->m_pkthdr.rcvif != NULL) {
  		ipoa.ipoa_boundif = m->m_pkthdr.rcvif->if_index;
  		ipoa.ipoa_flags |= IPOAF_BOUND_IF;
  	}
  
  	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
  	m->m_data += hlen;
  	m->m_len -= hlen;
  	icp = mtod(m, struct icmp *);
  	icp->icmp_cksum = 0;
  	icp->icmp_cksum = in_cksum(m, ip->ip_len - hlen);
  	m->m_data -= hlen;
  	m->m_len += hlen;
  	m->m_pkthdr.rcvif = NULL;
  	m->m_pkthdr.csum_data = 0;
  	m->m_pkthdr.csum_flags = 0;
  #if (DEBUG | DEVELOPMENT)
  	if (icmpprintfs > 2) {
  		char src_str[MAX_IPv4_STR_LEN];
  		char dst_str[MAX_IPv4_STR_LEN];
  
  		inet_ntop(AF_INET, &ip->ip_src, src_str, sizeof(src_str));
  		inet_ntop(AF_INET, &ip->ip_dst, dst_str, sizeof(dst_str));
  		printf("%s: dst %s src %s\n", __func__, dst_str, src_str);
  	}
  #endif
  	bzero(&ro, sizeof ro);
  	(void) ip_output(m, opts, &ro, IP_OUTARGS, NULL, &ipoa);
  	ROUTE_RELEASE(&ro);
  }
  
  u_int32_t
  iptime(void)
  {
  	struct timeval atv;
  	u_int32_t t;
  
  	getmicrotime(&atv);
  	t = (atv.tv_sec % (24 * 60 * 60)) * 1000 + atv.tv_usec / 1000;
  	return htonl(t);
  }
  
  #if 1
  /*
   * Return the next larger or smaller MTU plateau (table from RFC 1191)
   * given current value MTU.  If DIR is less than zero, a larger plateau
   * is returned; otherwise, a smaller value is returned.
   */
  int
  ip_next_mtu(int mtu, int dir)
  {
  	static int mtutab[] = {
  		65535, 32000, 17914, 8166, 4352, 2002, 1492, 1006, 508, 296,
  		68, 0
  	};
  	int i;
  
  	for (i = 0; i < (sizeof mtutab) / (sizeof mtutab[0]); i++) {
  		if (mtu >= mtutab[i]) {
  			break;
  		}
  	}
  
  	if (dir < 0) {
  		if (i == 0) {
  			return 0;
  		} else {
  			return mtutab[i - 1];
  		}
  	} else {
  		if (mtutab[i] == 0) {
  			return 0;
  		} else if (mtu > mtutab[i]) {
  			return mtutab[i];
  		} else {
  			return mtutab[i + 1];
  		}
  	}
  }
  #endif
  
  #if ICMP_BANDLIM
  
  /*
   * badport_bandlim() - check for ICMP bandwidth limit
   *
   *	Return 0 if it is ok to send an ICMP error response, -1 if we have
   *	hit our bandwidth limit and it is not ok.
   *
   *	If icmplim is <= 0, the feature is disabled and 0 is returned.
   *
   *	For now we separate the TCP and UDP subsystems w/ different 'which'
   *	values.  We may eventually remove this separation (and simplify the
   *	code further).
   *
   *	Note that the printing of the error message is delayed so we can
   *	properly print the icmp error rate that the system was trying to do
   *	(i.e. 22000/100 pps, etc...).  This can cause long delays in printing
   *	the 'final' error, but it doesn't make sense to solve the printing
   *	delay with more complex code.
   */
  
  int
  badport_bandlim(int which)
  {
  	static uint64_t lticks[BANDLIM_MAX + 1];
  	static int lpackets[BANDLIM_MAX + 1];
  	uint64_t time = net_uptime();
  	int secs;
  
  	const char *bandlimittype[] = {
  		"Limiting icmp unreach response",
  		"Limiting icmp ping response",
  		"Limiting icmp tstamp response",
  		"Limiting closed port RST response",
  		"Limiting open port RST response"
  	};
  
  	/*
  	 * Return ok status if feature disabled or argument out of
  	 * ranage.
  	 */
  
  	if (icmplim <= 0 || which > BANDLIM_MAX || which < 0) {
  		return 0;
  	}
  
  	secs = time - lticks[which];
  
  	/*
  	 * reset stats when cumulative delta exceeds one second.
  	 */
  
  	if (secs > 1) {
  		if (lpackets[which] > icmplim) {
  			printf("%s from %d to %d packets per second\n",
  			    bandlimittype[which],
  			    lpackets[which],
  			    icmplim
  			    );
  		}
  		lticks[which] = time;
  		lpackets[which] = 0;
  	}
  
  	/*
  	 * bump packet count
  	 */
  
  	if (++lpackets[which] > icmplim) {
  		return -1;
  	}
  	return 0;
  }
  
  #endif
  
  #if __APPLE__
  
  /*
   * Non-privileged ICMP socket operations
   * - send ICMP echo request
   * - all ICMP
   * - limited socket options
   */
  
  #include <netinet/ip_icmp.h>
  #include <netinet/in_pcb.h>
  
  extern u_int32_t rip_sendspace;
  extern u_int32_t rip_recvspace;
  extern struct inpcbinfo ripcbinfo;
  
  int rip_abort(struct socket *);
  int rip_bind(struct socket *, struct sockaddr *, struct proc *);
  int rip_connect(struct socket *, struct sockaddr *, struct proc *);
  int rip_detach(struct socket *);
  int rip_disconnect(struct socket *);
  int rip_shutdown(struct socket *);
  
  __private_extern__ int icmp_dgram_send(struct socket *so, int flags, struct mbuf *m, struct sockaddr *nam, struct mbuf *control, struct proc *p);
  __private_extern__ int icmp_dgram_attach(struct socket *so, int proto, struct proc *p);
  __private_extern__ int icmp_dgram_ctloutput(struct socket *so, struct sockopt *sopt);
  
  __private_extern__ struct pr_usrreqs icmp_dgram_usrreqs = {
  	.pru_abort =            rip_abort,
  	.pru_attach =           icmp_dgram_attach,
  	.pru_bind =             rip_bind,
  	.pru_connect =          rip_connect,
  	.pru_control =          in_control,
  	.pru_detach =           rip_detach,
  	.pru_disconnect =       rip_disconnect,
  	.pru_peeraddr =         in_getpeeraddr,
  	.pru_send =             icmp_dgram_send,
  	.pru_shutdown =         rip_shutdown,
  	.pru_sockaddr =         in_getsockaddr,
  	.pru_sosend =           sosend,
  	.pru_soreceive =        soreceive,
  };
  
  /* Like rip_attach but without root privilege enforcement */
  __private_extern__ int
  icmp_dgram_attach(struct socket *so, __unused int proto, struct proc *p)
  {
  	struct inpcb *inp;
  	int error;
  
  	inp = sotoinpcb(so);
  	if (inp) {
  		panic("icmp_dgram_attach");
  	}
  
  	error = soreserve(so, rip_sendspace, rip_recvspace);
  	if (error) {
  		return error;
  	}
  	error = in_pcballoc(so, &ripcbinfo, p);
  	if (error) {
  		return error;
  	}
  	inp = (struct inpcb *)so->so_pcb;
  	inp->inp_vflag |= INP_IPV4;
  	inp->inp_ip_p = IPPROTO_ICMP;
  	inp->inp_ip_ttl = ip_defttl;
  	return 0;
  }
  
  /*
   * Raw IP socket option processing.
   */
  __private_extern__ int
  icmp_dgram_ctloutput(struct socket *so, struct sockopt *sopt)
  {
  	int     error;
  
  	if (sopt->sopt_level != IPPROTO_IP) {
  		return EINVAL;
  	}
  
  	switch (sopt->sopt_name) {
  	case IP_OPTIONS:
  	case IP_HDRINCL:
  	case IP_TOS:
  	case IP_TTL:
  	case IP_RECVOPTS:
  	case IP_RECVRETOPTS:
  	case IP_RECVDSTADDR:
  	case IP_RETOPTS:
  	case IP_MULTICAST_IF:
  	case IP_MULTICAST_IFINDEX:
  	case IP_MULTICAST_TTL:
  	case IP_MULTICAST_LOOP:
  	case IP_ADD_MEMBERSHIP:
  	case IP_DROP_MEMBERSHIP:
  	case IP_MULTICAST_VIF:
  	case IP_PORTRANGE:
  	case IP_RECVIF:
  	case IP_IPSEC_POLICY:
  	case IP_STRIPHDR:
  	case IP_RECVTTL:
  	case IP_BOUND_IF:
  	case IP_NO_IFT_CELLULAR:
  		error = rip_ctloutput(so, sopt);
  		break;
  
  	default:
  		error = EINVAL;
  		break;
  	}
  
  	return error;
  }
  
  __private_extern__ int
  icmp_dgram_send(struct socket *so, int flags, struct mbuf *m,
      struct sockaddr *nam, struct mbuf *control, struct proc *p)
  {
  	struct ip *ip;
  	struct inpcb *inp = sotoinpcb(so);
  	int hlen;
  	struct icmp *icp;
  	struct in_ifaddr *ia = NULL;
  	int icmplen;
  	int error = EINVAL;
  
  	if (inp == NULL
  #if NECP
  	    || (necp_socket_should_use_flow_divert(inp))
  #endif /* NECP */
  	    ) {
  		if (inp != NULL) {
  			error = EPROTOTYPE;
  		}
  		goto bad;
  	}
  
  	if ((inp->inp_flags & INP_HDRINCL) != 0) {
  		/* Expect 32-bit aligned data ptr on strict-align platforms */
  		MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m);
  		/*
  		 * This is not raw IP, we liberal only for fields TOS,
  		 * id and TTL.
  		 */
  		ip = mtod(m, struct ip *);
  
  		hlen = IP_VHL_HL(ip->ip_vhl) << 2;
  		/* Some sanity checks */
  		if (m->m_pkthdr.len < hlen + ICMP_MINLEN) {
  			goto bad;
  		}
  		/* Only IPv4 */
  		if (IP_VHL_V(ip->ip_vhl) != 4) {
  			goto bad;
  		}
  		if (hlen < 20 || hlen > 40 || ip->ip_len != m->m_pkthdr.len) {
  			goto bad;
  		}
  		/* Bogus fragments can tie up peer resources */
  		if ((ip->ip_off & ~IP_DF) != 0) {
  			goto bad;
  		}
  		/* Allow only ICMP even for user provided IP header */
  		if (ip->ip_p != IPPROTO_ICMP) {
  			goto bad;
  		}
  		/*
  		 * To prevent spoofing, specified source address must
  		 * be one of ours.
  		 */
  		if (ip->ip_src.s_addr != INADDR_ANY) {
  			socket_unlock(so, 0);
  			lck_rw_lock_shared(in_ifaddr_rwlock);
  			if (TAILQ_EMPTY(&in_ifaddrhead)) {
  				lck_rw_done(in_ifaddr_rwlock);
  				socket_lock(so, 0);
  				goto bad;
  			}
  			TAILQ_FOREACH(ia, INADDR_HASH(ip->ip_src.s_addr),
  			    ia_hash) {
  				IFA_LOCK(&ia->ia_ifa);
  				if (IA_SIN(ia)->sin_addr.s_addr ==
  				    ip->ip_src.s_addr) {
  					IFA_UNLOCK(&ia->ia_ifa);
  					lck_rw_done(in_ifaddr_rwlock);
  					socket_lock(so, 0);
  					goto ours;
  				}
  				IFA_UNLOCK(&ia->ia_ifa);
  			}
  			lck_rw_done(in_ifaddr_rwlock);
  			socket_lock(so, 0);
  			goto bad;
  		}
  ours:
  		/* Do not trust we got a valid checksum */
  		ip->ip_sum = 0;
  
  		icp = (struct icmp *)(void *)(((char *)m->m_data) + hlen);
  		icmplen = m->m_pkthdr.len - hlen;
  	} else {
  		if ((icmplen = m->m_pkthdr.len) < ICMP_MINLEN) {
  			goto bad;
  		}
  		icp = mtod(m, struct icmp *);
  	}
  	/*
  	 * Allow only to send request types with code 0
  	 */
  	if (icp->icmp_code != 0) {
  		goto bad;
  	}
  	switch (icp->icmp_type) {
  	case ICMP_ECHO:
  		break;
  	case ICMP_TSTAMP:
  		if (icmplen != 20) {
  			goto bad;
  		}
  		break;
  	case ICMP_MASKREQ:
  		if (icmplen != 12) {
  			goto bad;
  		}
  		break;
  	default:
  		goto bad;
  	}
  	return rip_send(so, flags, m, nam, control, p);
  bad:
  	VERIFY(error != 0);
  
  	if (m != NULL) {
  		m_freem(m);
  	}
  	if (control != NULL) {
  		m_freem(control);
  	}
  
  	return error;
  }
  
  #endif /* __APPLE__ */
  