xref: /src/external/apache2/mDNSResponder/dist/mDNSPosix/mDNSBSD.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 <ifaddrs.h>

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netinet/in_var.h>
#include <net/if_dl.h>

static int
copyaddr(struct sockaddr **dst, const struct sockaddr *src, socklen_t len)
{
	if (src == NULL)
		return 1;

	*dst = calloc(1, len);
	if (*dst == NULL)
		return 0;

	memcpy(*dst, src, len);
	return 1;
}

struct ifi_info *
get_ifi_info(int family, int doaliases)
{
	struct ifi_info *ifi, *ifihead, **ifipnext, *ifipold, **ifiptr;
	struct ifaddrs *ifal, *ifa;

	if (getifaddrs(&ifal) == -1) {
		warn("getifaddrs");
		return NULL;
	}

	ifihead = NULL;
	ifipnext = &ifihead;

	for (ifa = ifal; ifa; ifa = ifa->ifa_next) {
		struct sockaddr *sa = ifa->ifa_addr;
		int flags = ifa->ifa_flags;
		int addrflags = ifa->ifa_addrflags;

#if 0
		/*
		 * Include the loopback so that we return at least one
		 * address, so that mdnsd does not exit before we get
		 * a dhcp address
		 */
		if (flags & IFF_LOOPBACK)
			continue;	/* ignore loopback interfaces */
#endif

		if ((flags & IFF_UP) == 0)
			continue;	/* ignore if interface not up */

		if (sa == NULL || sa->sa_family != family)
			continue; 	/* ignore if not the desired family */

		switch (sa->sa_family) {
		case AF_INET:
			if (addrflags & (IN_IFF_NOTREADY | IN_IFF_DETACHED))
				continue;

			break;
#if defined(AF_INET6) && HAVE_IPV6
		case AF_INET6:
			if (addrflags & (IN6_IFF_NOTREADY | IN6_IFF_DETACHED))
				continue;
#endif
			break;
		default:
			continue;
		}

		ifi = calloc(1, sizeof(*ifi));
		if (ifi == NULL)
			goto gotError;

		ifipold   = *ifipnext;		/* need this later */
		ifiptr    = ifipnext;
		*ifipnext = ifi;		/* prev points to new one */
		ifipnext  = &ifi->ifi_next;	/* pointer to next one */

		ifi->ifi_flags = flags;		/* IFF_xxx values */
		ifi->ifi_myflags = 0;		/* IFI_xxx values */
		ifi->ifi_index = if_nametoindex(ifa->ifa_name);
		memcpy(ifi->ifi_name, ifa->ifa_name, IFI_NAME);
		ifi->ifi_name[IFI_NAME-1] = '\0';
		if (!copyaddr(&ifi->ifi_addr, ifa->ifa_addr, sa->sa_len))
			goto gotError;
		if (!copyaddr(&ifi->ifi_netmask, ifa->ifa_netmask, sa->sa_len))
			goto gotError;

		if ((flags & IFF_BROADCAST) && !copyaddr(&ifi->ifi_brdaddr,
		    ifa->ifa_broadaddr, sa->sa_len))
			goto gotError;
		if ((flags & IFF_POINTOPOINT) && !copyaddr(&ifi->ifi_dstaddr,
		    ifa->ifa_dstaddr, sa->sa_len))
			goto gotError;
	}

	goto done;

gotError:
	warn("can't allocate memory");
	if (ifihead != NULL) {
		free_ifi_info(ifihead);
		ifihead = NULL;
	}

	freeifaddrs(ifal);
done:
	return ifihead;    /* pointer to first structure in linked list */
}

void
free_ifi_info(struct ifi_info *ifihead)
{
	struct ifi_info *ifi, *ififree;

	for (ifi = ifihead; (ififree = ifi) != NULL;) {
		free(ifi->ifi_addr);
		free(ifi->ifi_netmask);
		free(ifi->ifi_brdaddr);
		free(ifi->ifi_dstaddr);
		ifi = ifi->ifi_next;
		free(ififree);
	}
}

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 */
}