mDNSPosix/mDNSUNP.c

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2002-2004 Apple Computer, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "mDNSUNP.h"

#include <errno.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <sys/uio.h>
#include <sys/ioctl.h>
#include <signal.h>
#include <unistd.h>
#include <stdio.h>

/* Some weird platforms derived from 4.4BSD Lite (e.g. EFI) need the ALIGN(P)
   macro, usually defined in <sys/param.h> or someplace like that, to make sure the
   CMSG_NXTHDR macro is well-formed. On such platforms, the symbol NEED_ALIGN_MACRO
   should be set to the name of the header to include to get the ALIGN(P) macro.
*/
#ifdef NEED_ALIGN_MACRO
#include NEED_ALIGN_MACRO
#endif

/* Solaris defined SIOCGIFCONF etc in <sys/sockio.h> but 
   other platforms don't even have that include file.  So, 
   if we haven't yet got a definition, let's try to find 
   <sys/sockio.h>.
*/

#ifndef SIOCGIFCONF
    #include <sys/sockio.h>
#endif

/* sockaddr_dl is only referenced if we're using IP_RECVIF, 
   so only include the header in that case.
*/

#ifdef  IP_RECVIF
    #include <net/if_dl.h>
#endif

#if defined(AF_INET6) && HAVE_IPV6 && !HAVE_LINUX
#include <net/if_var.h>
#include <netinet/in_var.h>
// Note: netinet/in_var.h implicitly includes netinet6/in6_var.h for us
#endif

#if defined(AF_INET6) && HAVE_IPV6 && HAVE_LINUX
#include <netdb.h>
#include <arpa/inet.h>

/* Converts a prefix length to IPv6 network mask */
void plen_to_mask(int plen, char *addr) {
	int i;
	int colons=7; /* Number of colons in IPv6 address */
	int bits_in_block=16; /* Bits per IPv6 block */
	for(i=0;i<=colons;i++) {
		int block, ones=0xffff, ones_in_block;
		if (plen>bits_in_block) ones_in_block=bits_in_block;
		else                    ones_in_block=plen;
		block = ones & (ones << (bits_in_block-ones_in_block));
		i==0 ? sprintf(addr, "%x", block) : sprintf(addr, "%s:%x", addr, block);
		plen -= ones_in_block;
		}
	}

/* Gets IPv6 interface information from the /proc filesystem in linux*/
struct ifi_info *get_ifi_info_linuxv6(int family, int doaliases)
	{
		struct ifi_info *ifi, *ifihead, **ifipnext, *ifipold, **ifiptr;
	FILE *fp = NULL;
	char addr[8][5];
	int flags, myflags, index, plen, scope;
	char ifname[9], lastname[IFNAMSIZ];
	char addr6[32+7+1]; /* don't forget the seven ':' */
	struct addrinfo hints, *res0;
	struct sockaddr_in6 *sin6;
	struct in6_addr *addrptr;
	int err;
	int sockfd = -1;
	struct ifreq ifr;

	res0=NULL;
	ifihead = NULL;
	ifipnext = &ifihead;
	lastname[0] = 0;

	if ((fp = fopen(PROC_IFINET6_PATH, "r")) != NULL) {
		sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
		if (sockfd < 0) {
			goto gotError;
		}
		while (fscanf(fp,
					  "%4s%4s%4s%4s%4s%4s%4s%4s %02x %02x %02x %02x %8s\n",
					  addr[0],addr[1],addr[2],addr[3],
					  addr[4],addr[5],addr[6],addr[7],
					  &index, &plen, &scope, &flags, ifname) != EOF) {

			myflags = 0;
			if (strncmp(lastname, ifname, IFNAMSIZ) == 0) {
				if (doaliases == 0)
					continue;   /* already processed this interface */
				myflags = IFI_ALIAS;
				}
			strncpy(lastname, ifname, IFNAMSIZ);
			ifi = (struct ifi_info*)calloc(1, sizeof(struct ifi_info));
			if (ifi == NULL) {
				goto gotError;
			}
			
			ifipold   = *ifipnext;       /* need this later */
			ifiptr    = ifipnext;
			*ifipnext = ifi;            /* prev points to this new one */
			ifipnext = &ifi->ifi_next;  /* pointer to next one goes here */

			sprintf(addr6, "%s:%s:%s:%s:%s:%s:%s:%s",
					addr[0],addr[1],addr[2],addr[3],
					addr[4],addr[5],addr[6],addr[7]);

			/* Add address of the interface */
			memset(&hints, 0, sizeof(hints));
			hints.ai_family = AF_INET6;
			hints.ai_flags = AI_NUMERICHOST;
			err = getaddrinfo(addr6, NULL, &hints, &res0);
			if (err) {
				goto gotError;
				}
			ifi->ifi_addr = calloc(1, sizeof(struct sockaddr_in6));
			if (ifi->ifi_addr == NULL) {
				goto gotError;
				}
			memcpy(ifi->ifi_addr, res0->ai_addr, sizeof(struct sockaddr_in6));

			/* Add netmask of the interface */
			char ipv6addr[INET6_ADDRSTRLEN];
			plen_to_mask(plen, ipv6addr);
			ifi->ifi_netmask = calloc(1, sizeof(struct sockaddr_in6));
			if (ifi->ifi_addr == NULL) {
				goto gotError;
				}
			sin6=calloc(1, sizeof(struct sockaddr_in6));
			addrptr=calloc(1, sizeof(struct in6_addr));
			inet_pton(family, ipv6addr, addrptr);
			sin6->sin6_family=family;
			sin6->sin6_addr=*addrptr;
			sin6->sin6_scope_id=scope;
			memcpy(ifi->ifi_netmask, sin6, sizeof(struct sockaddr_in6));
			free(sin6);


			/* Add interface name */
			strncpy(ifi->ifi_name, ifname, IFI_NAME);

			/* Add interface index */
			ifi->ifi_index = index;

			/* Add interface flags*/
			strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
			if (ioctl(sockfd, SIOCGIFFLAGS, &ifr) < 0) {
				if (errno == EADDRNOTAVAIL) {
					/* 
					 * If the main interface is configured with no IP address but 
					 * an alias interface exists with an IP address, you get 
					 * EADDRNOTAVAIL for the main interface 
					 */
					free(ifi->ifi_addr);
					free(ifi);
					ifipnext  = ifiptr; 
					*ifipnext = ifipold;
					continue;
				} else {
					goto gotError;
				}
			}
			ifi->ifi_flags = ifr.ifr_flags;
			freeaddrinfo(res0);
			res0=NULL;
			}
		}
	goto done;

	gotError:
	if (ifihead != NULL) {
		free_ifi_info(ifihead);
		ifihead = NULL;
		}
	if (res0 != NULL) {
		freeaddrinfo(res0);
		res0=NULL;
		}
	done:
	if (sockfd != -1) {
// __ANDROID__ : replaced assert(close(..))
		int sockfd_closed = close(sockfd);
		assert(sockfd_closed == 0);
		}
// __ANDROID__ : if fp was opened, it needs to be closed
	if (fp != NULL) {
		int fd_closed = fclose(fp);
		assert(fd_closed == 0);
		}
	return(ifihead);    /* pointer to first structure in linked list */
	}
#endif // defined(AF_INET6) && HAVE_IPV6 && HAVE_LINUX

struct ifi_info *get_ifi_info(int family, int doaliases)
{
    int                 junk;
    struct ifi_info     *ifi, *ifihead, **ifipnext, *ifipold, **ifiptr;
    int                 sockfd, sockf6, len, lastlen, flags, myflags;
#ifdef NOT_HAVE_IF_NAMETOINDEX
    int                 index = 200;
#endif
    char                *ptr, *buf, lastname[IFNAMSIZ], *cptr;
    struct ifconf       ifc;
    struct ifreq        *ifr, ifrcopy;
    struct sockaddr_in  *sinptr;
    
#if defined(AF_INET6) && HAVE_IPV6
    struct sockaddr_in6 *sinptr6;
#endif

#if defined(AF_INET6) && HAVE_IPV6 && HAVE_LINUX
 if (family == AF_INET6) return get_ifi_info_linuxv6(family, doaliases);
#endif

	sockfd = -1;
    sockf6 = -1;
    buf = NULL;
    ifihead = NULL;
    
    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0) {
        goto gotError;
    }

    lastlen = 0;
    len = 100 * sizeof(struct ifreq);   /* initial buffer size guess */
    for ( ; ; ) {
        buf = (char*)malloc(len);
        if (buf == NULL) {
            goto gotError;
        }
        ifc.ifc_len = len;
        ifc.ifc_buf = buf;
        if (ioctl(sockfd, SIOCGIFCONF, &ifc) < 0) {
            if (errno != EINVAL || lastlen != 0) {
                goto gotError;
            }
        } else {
            if (ifc.ifc_len == lastlen)
                break;      /* success, len has not changed */
            lastlen = ifc.ifc_len;
        }
        len += 10 * sizeof(struct ifreq);   /* increment */
        free(buf);
    }
    ifihead = NULL;
    ifipnext = &ifihead;
    lastname[0] = 0;
/* end get_ifi_info1 */

/* include get_ifi_info2 */
    for (ptr = buf; ptr < buf + ifc.ifc_len; ) {
        ifr = (struct ifreq *) ptr;

        /* Advance to next one in buffer */
        if (sizeof(struct ifreq) > sizeof(ifr->ifr_name) + GET_SA_LEN(ifr->ifr_addr))
            ptr += sizeof(struct ifreq);
        else
            ptr += sizeof(ifr->ifr_name) + GET_SA_LEN(ifr->ifr_addr);

//      fprintf(stderr, "intf %p name=%s AF=%d\n", index, ifr->ifr_name, ifr->ifr_addr.sa_family);
        
        if (ifr->ifr_addr.sa_family != family)
            continue;   /* ignore if not desired address family */

        myflags = 0;
        if ( (cptr = strchr(ifr->ifr_name, ':')) != NULL)
            *cptr = 0;      /* replace colon will null */
        if (strncmp(lastname, ifr->ifr_name, IFNAMSIZ) == 0) {
            if (doaliases == 0)
                continue;   /* already processed this interface */
            myflags = IFI_ALIAS;
        }
        memcpy(lastname, ifr->ifr_name, IFNAMSIZ);

        ifrcopy = *ifr;
        if (ioctl(sockfd, SIOCGIFFLAGS, &ifrcopy) < 0) {
            goto gotError;
        }
        
        flags = ifrcopy.ifr_flags;
        if ((flags & IFF_UP) == 0)
            continue;   /* ignore if interface not up */

        ifi = (struct ifi_info*)calloc(1, sizeof(struct ifi_info));
        if (ifi == NULL) {
            goto gotError;
        }
		ifipold   = *ifipnext;       /* need this later */
		ifiptr    = ifipnext;
		*ifipnext = ifi;             /* prev points to this new one */
		ifipnext  = &ifi->ifi_next;  /* pointer to next one goes here */
		
        ifi->ifi_flags = flags;     /* IFF_xxx values */
        ifi->ifi_myflags = myflags; /* IFI_xxx values */
#ifndef NOT_HAVE_IF_NAMETOINDEX
        ifi->ifi_index = if_nametoindex(ifr->ifr_name);
#else
        ifrcopy = *ifr;
#ifdef SIOCGIFINDEX
		if ( 0 >= ioctl(sockfd, SIOCGIFINDEX, &ifrcopy))
            ifi->ifi_index = ifrcopy.ifr_index;
        else
#endif
            ifi->ifi_index = index++;	/* SIOCGIFINDEX is broken on Solaris 2.5ish, so fake it */
#endif
        memcpy(ifi->ifi_name, ifr->ifr_name, IFI_NAME);
        ifi->ifi_name[IFI_NAME-1] = '\0';
/* end get_ifi_info2 */
/* include get_ifi_info3 */
        switch (ifr->ifr_addr.sa_family) {
        case AF_INET:
            sinptr = (struct sockaddr_in *) &ifr->ifr_addr;
            if (ifi->ifi_addr == NULL) {
                ifi->ifi_addr = (struct sockaddr*)calloc(1, sizeof(struct sockaddr_in));
                if (ifi->ifi_addr == NULL) {
                    goto gotError;
                }
                memcpy(ifi->ifi_addr, sinptr, sizeof(struct sockaddr_in));

#ifdef  SIOCGIFNETMASK
				if (ioctl(sockfd, SIOCGIFNETMASK, &ifrcopy) < 0) {
					if (errno == EADDRNOTAVAIL) {
						/* 
						 * If the main interface is configured with no IP address but 
						 * an alias interface exists with an IP address, you get 
						 * EADDRNOTAVAIL for the main interface 
						 */
						free(ifi->ifi_addr);
						free(ifi);
						ifipnext  = ifiptr; 
						*ifipnext = ifipold;
						continue;
					} else {
						goto gotError;
					}				
				}

				ifi->ifi_netmask = (struct sockaddr*)calloc(1, sizeof(struct sockaddr_in));
				if (ifi->ifi_netmask == NULL) goto gotError;
				sinptr = (struct sockaddr_in *) &ifrcopy.ifr_addr;
				/* The BSD ioctls (including Mac OS X) stick some weird values in for sin_len and sin_family */
#ifndef NOT_HAVE_SA_LEN
				sinptr->sin_len    = sizeof(struct sockaddr_in);
#endif
				sinptr->sin_family = AF_INET;
				memcpy(ifi->ifi_netmask, sinptr, sizeof(struct sockaddr_in));
#endif

#ifdef  SIOCGIFBRDADDR
                if (flags & IFF_BROADCAST) {
                    if (ioctl(sockfd, SIOCGIFBRDADDR, &ifrcopy) < 0) {
                        goto gotError;
                    }
                    sinptr = (struct sockaddr_in *) &ifrcopy.ifr_broadaddr;
					/* The BSD ioctls (including Mac OS X) stick some weird values in for sin_len and sin_family */
#ifndef NOT_HAVE_SA_LEN
					sinptr->sin_len    = sizeof( struct sockaddr_in );
#endif
					sinptr->sin_family = AF_INET;
                    ifi->ifi_brdaddr = (struct sockaddr*)calloc(1, sizeof(struct sockaddr_in));
                    if (ifi->ifi_brdaddr == NULL) {
                        goto gotError;
                    }
                    memcpy(ifi->ifi_brdaddr, sinptr, sizeof(struct sockaddr_in));
                }
#endif

#ifdef  SIOCGIFDSTADDR
                if (flags & IFF_POINTOPOINT) {
                    if (ioctl(sockfd, SIOCGIFDSTADDR, &ifrcopy) < 0) {
                        goto gotError;
                    }
                    sinptr = (struct sockaddr_in *) &ifrcopy.ifr_dstaddr;
                    /* The BSD ioctls (including Mac OS X) stick some weird values in for sin_len and sin_family */
#ifndef NOT_HAVE_SA_LEN
					sinptr->sin_len    = sizeof( struct sockaddr_in );
#endif
					sinptr->sin_family = AF_INET;
                    ifi->ifi_dstaddr = (struct sockaddr*)calloc(1, sizeof(struct sockaddr_in));
                    if (ifi->ifi_dstaddr == NULL) {
                        goto gotError;
                    }
                    memcpy(ifi->ifi_dstaddr, sinptr, sizeof(struct sockaddr_in));
                }
#endif
            }
            break;

#if defined(AF_INET6) && HAVE_IPV6
        case AF_INET6:
            sinptr6 = (struct sockaddr_in6 *) &ifr->ifr_addr;
            if (ifi->ifi_addr == NULL) {
                ifi->ifi_addr = calloc(1, sizeof(struct sockaddr_in6));
                if (ifi->ifi_addr == NULL) {
                    goto gotError;
                }
                
                /* Some platforms (*BSD) inject the prefix in IPv6LL addresses */
                /* We need to strip that out */
                if (IN6_IS_ADDR_LINKLOCAL(&sinptr6->sin6_addr))
                	sinptr6->sin6_addr.s6_addr[2] = sinptr6->sin6_addr.s6_addr[3] = 0;
                memcpy(ifi->ifi_addr, sinptr6, sizeof(struct sockaddr_in6));

#ifdef  SIOCGIFNETMASK_IN6
				{
				struct in6_ifreq ifr6;
				if (sockf6 == -1)
					sockf6 = socket(AF_INET6, SOCK_DGRAM, 0);
				memset(&ifr6, 0, sizeof(ifr6));
				memcpy(&ifr6.ifr_name,           &ifr->ifr_name, sizeof(ifr6.ifr_name          ));
				memcpy(&ifr6.ifr_ifru.ifru_addr, &ifr->ifr_addr, sizeof(ifr6.ifr_ifru.ifru_addr));
				if (ioctl(sockf6, SIOCGIFNETMASK_IN6, &ifr6) < 0) {
					if (errno == EADDRNOTAVAIL) {
						/* 
						 * If the main interface is configured with no IP address but 
						 * an alias interface exists with an IP address, you get 
						 * EADDRNOTAVAIL for the main interface 
						 */
						free(ifi->ifi_addr);
						free(ifi);
						ifipnext  = ifiptr; 
						*ifipnext = ifipold;
						continue;
					} else {
						goto gotError;
					}				
				}
				ifi->ifi_netmask = (struct sockaddr*)calloc(1, sizeof(struct sockaddr_in6));
				if (ifi->ifi_netmask == NULL) goto gotError;
				sinptr6 = (struct sockaddr_in6 *) &ifr6.ifr_ifru.ifru_addr;
				memcpy(ifi->ifi_netmask, sinptr6, sizeof(struct sockaddr_in6));
				}
#endif
            }
            break;
#endif

        default:
            break;
        }
    }
    goto done;
    
gotError:
    if (ifihead != NULL) {
        free_ifi_info(ifihead);
        ifihead = NULL;
    }

done:
    if (buf != NULL) {
        free(buf);
    }
    if (sockfd != -1) {
        junk = close(sockfd);
        assert(junk == 0);
    }
    if (sockf6 != -1) {
        junk = close(sockf6);
        assert(junk == 0);
    }
    return(ifihead);    /* pointer to first structure in linked list */
}
/* end get_ifi_info3 */

/* include free_ifi_info */
void
free_ifi_info(struct ifi_info *ifihead)
{
    struct ifi_info *ifi, *ifinext;

    for (ifi = ifihead; ifi != NULL; ifi = ifinext) {
        if (ifi->ifi_addr != NULL)
            free(ifi->ifi_addr);
        if (ifi->ifi_netmask != NULL)
            free(ifi->ifi_netmask);
        if (ifi->ifi_brdaddr != NULL)
            free(ifi->ifi_brdaddr);
        if (ifi->ifi_dstaddr != NULL)
            free(ifi->ifi_dstaddr);
        ifinext = ifi->ifi_next;    /* can't fetch ifi_next after free() */
        free(ifi);                  /* the ifi_info{} itself */
    }
}
/* end free_ifi_info */

ssize_t 
recvfrom_flags(int fd, void *ptr, size_t nbytes, int *flagsp,
               struct sockaddr *sa, socklen_t *salenptr, struct my_in_pktinfo *pktp, u_char *ttl)
{
    struct msghdr   msg;
    struct iovec    iov[1];
    ssize_t         n;

#ifdef CMSG_FIRSTHDR
    struct cmsghdr  *cmptr;
    union {
      struct cmsghdr    cm;
      char              control[1024];
    } control_un;

	*ttl = 255;			// If kernel fails to provide TTL data then assume the TTL was 255 as it should be

    msg.msg_control = control_un.control;
    msg.msg_controllen = sizeof(control_un.control);
    msg.msg_flags = 0;
#else
    memset(&msg, 0, sizeof(msg));   /* make certain msg_accrightslen = 0 */
#endif /* CMSG_FIRSTHDR */

    msg.msg_name = (char *) sa;
    msg.msg_namelen = *salenptr;
    iov[0].iov_base = (char *)ptr;
    iov[0].iov_len = nbytes;
    msg.msg_iov = iov;
    msg.msg_iovlen = 1;

    if ( (n = recvmsg(fd, &msg, *flagsp)) < 0)
        return(n);

    *salenptr = msg.msg_namelen;    /* pass back results */
    if (pktp) {
        /* 0.0.0.0, i/f = -1 */
        /* We set the interface to -1 so that the caller can 
           tell whether we returned a meaningful value or 
           just some default.  Previously this code just 
           set the value to 0, but I'm concerned that 0 
           might be a valid interface value.
        */
        memset(pktp, 0, sizeof(struct my_in_pktinfo));
        pktp->ipi_ifindex = -1;
    }
/* end recvfrom_flags1 */

/* include recvfrom_flags2 */
#ifndef CMSG_FIRSTHDR
	#warning CMSG_FIRSTHDR not defined. Will not be able to determine destination address, received interface, etc.
    *flagsp = 0;                    /* pass back results */
    return(n);
#else

    *flagsp = msg.msg_flags;        /* pass back results */
    if (msg.msg_controllen < (socklen_t)sizeof(struct cmsghdr) ||
        (msg.msg_flags & MSG_CTRUNC) || pktp == NULL)
        return(n);

    for (cmptr = CMSG_FIRSTHDR(&msg); cmptr != NULL;
         cmptr = CMSG_NXTHDR(&msg, cmptr)) {

#ifdef  IP_PKTINFO
#if in_pktinfo_definition_is_missing
struct in_pktinfo
{
        int             ipi_ifindex;
        struct in_addr  ipi_spec_dst;
        struct in_addr  ipi_addr;
};
#endif
        if (cmptr->cmsg_level == IPPROTO_IP && 
            cmptr->cmsg_type == IP_PKTINFO) {
            struct in_pktinfo *tmp;
            struct sockaddr_in *sin = (struct sockaddr_in*)&pktp->ipi_addr;
            
            tmp = (struct in_pktinfo *) CMSG_DATA(cmptr);
            sin->sin_family = AF_INET;
            sin->sin_addr = tmp->ipi_addr;
            sin->sin_port = 0;
            pktp->ipi_ifindex = tmp->ipi_ifindex;
            continue;
        }
#endif

#ifdef  IP_RECVDSTADDR
        if (cmptr->cmsg_level == IPPROTO_IP &&
            cmptr->cmsg_type == IP_RECVDSTADDR) {
            struct sockaddr_in *sin = (struct sockaddr_in*)&pktp->ipi_addr;
            
            sin->sin_family = AF_INET;
            sin->sin_addr = *(struct in_addr*)CMSG_DATA(cmptr);
            sin->sin_port = 0;
            continue;
        }
#endif

#ifdef  IP_RECVIF
        if (cmptr->cmsg_level == IPPROTO_IP &&
            cmptr->cmsg_type == IP_RECVIF) {
            struct sockaddr_dl  *sdl = (struct sockaddr_dl *) CMSG_DATA(cmptr);
#ifndef HAVE_BROKEN_RECVIF_NAME
            int nameLen = (sdl->sdl_nlen < IFI_NAME - 1) ? sdl->sdl_nlen : (IFI_NAME - 1);
            strncpy(pktp->ipi_ifname, sdl->sdl_data, nameLen);
#endif
            pktp->ipi_ifindex = sdl->sdl_index;
#ifdef HAVE_BROKEN_RECVIF_NAME
			if (sdl->sdl_index == 0) {
				pktp->ipi_ifindex = *(uint_t*)sdl;
			}
#endif            
            assert(pktp->ipi_ifname[IFI_NAME - 1] == 0);
            // null terminated because of memset above
            continue;
        }
#endif

#ifdef  IP_RECVTTL
        if (cmptr->cmsg_level == IPPROTO_IP &&
            cmptr->cmsg_type == IP_RECVTTL) {
			*ttl = *(u_char*)CMSG_DATA(cmptr);
            continue;
        }
        else if (cmptr->cmsg_level == IPPROTO_IP &&
            cmptr->cmsg_type == IP_TTL) {		// some implementations seem to send IP_TTL instead of IP_RECVTTL
			*ttl = *(int*)CMSG_DATA(cmptr);
            continue;
        }
#endif

#if defined(IPV6_PKTINFO) && HAVE_IPV6 
		if (cmptr->cmsg_level == IPPROTO_IPV6 && 
            cmptr->cmsg_type  == IPV6_2292_PKTINFO) {
            struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)&pktp->ipi_addr;
			struct in6_pktinfo *ip6_info = (struct in6_pktinfo*)CMSG_DATA(cmptr);
			
            sin6->sin6_family   = AF_INET6;
#ifndef NOT_HAVE_SA_LEN
            sin6->sin6_len      = sizeof(*sin6);
#endif
            sin6->sin6_addr     = ip6_info->ipi6_addr;
            sin6->sin6_flowinfo = 0;
            sin6->sin6_scope_id = 0;
            sin6->sin6_port     = 0;
			pktp->ipi_ifindex   = ip6_info->ipi6_ifindex;
            continue;
        }
#endif

#if defined(IPV6_HOPLIMIT) && HAVE_IPV6
        if (cmptr->cmsg_level == IPPROTO_IPV6 && 
            cmptr->cmsg_type == IPV6_2292_HOPLIMIT) {
			*ttl = *(int*)CMSG_DATA(cmptr);
            continue;
        }
#endif
        assert(0);  // unknown ancillary data
    }
    return(n);
#endif /* CMSG_FIRSTHDR */
}

// **********************************************************************************************

// daemonize the process. Adapted from "Unix Network Programming" vol 1 by Stevens, section 12.4.
// Returns 0 on success, -1 on failure.

#ifdef NOT_HAVE_DAEMON
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/signal.h>

int daemon(int nochdir, int noclose)
    {
	switch (fork())
		{
		case -1: return (-1);	// Fork failed
		case 0: break;		// Child -- continue
		default: _exit(0);	// Parent -- exit
		}

	if (setsid() == -1) return(-1);

	signal(SIGHUP, SIG_IGN);

	switch (fork())				// Fork again, primarily for reasons of Unix trivia
		{
		case -1: return (-1);	// Fork failed
		case 0:  break;			// Child -- continue
		default: _exit(0);		// Parent -- exit
		}

	if (!nochdir) (void)chdir("/");
	umask(0);

	if (!noclose)
		{
		int fd = open("/dev/null", O_RDWR, 0);
		if (fd != -1)
			{
			// Avoid unnecessarily duplicating a file descriptor to itself
			if (fd != STDIN_FILENO) (void)dup2(fd, STDIN_FILENO);
			if (fd != STDOUT_FILENO) (void)dup2(fd, STDOUT_FILENO);
			if (fd != STDERR_FILENO) (void)dup2(fd, STDERR_FILENO);
			if (fd != STDIN_FILENO && fd != STDOUT_FILENO && fd != STDERR_FILENO) 
				(void)close (fd);
			}
		}
	return (0);
    }
#endif /* NOT_HAVE_DAEMON */