X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fsocket.c;fp=src%2Fsocket.c;h=151625aea5ce6e2fa1e27a563abd04a573069b06;hb=37d19f15523b6fe4d1fef2329abe421221b3d4b3;hp=0000000000000000000000000000000000000000;hpb=e8d28c50c6d3a73d1a6f514095304bfe0973ff2a;p=catta

diff --git a/src/socket.c b/src/socket.c
new file mode 100644
index 0000000..151625a
--- /dev/null
+++ b/src/socket.c
@@ -0,0 +1,993 @@
+/***
+  This file is part of avahi.
+
+  avahi is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  avahi is distributed in the hope that it will be useful, but WITHOUT
+  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
+  Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with avahi; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+  USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <inttypes.h>
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/ioctl.h>
+#ifdef HAVE_SYS_FILIO_H
+#include <sys/filio.h>
+#endif
+#include <assert.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <net/if.h>
+#include <sys/uio.h>
+
+#ifdef IP_RECVIF
+#include <net/if_dl.h>
+#endif
+
+#include <avahi/log.h>
+#include "dns.h"
+#include "fdutil.h"
+#include "socket.h"
+#include "addr-util.h"
+
+/* this is a portability hack */
+#ifndef IPV6_ADD_MEMBERSHIP
+#ifdef  IPV6_JOIN_GROUP
+#define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
+#endif
+#endif
+
+#ifndef IPV6_DROP_MEMBERSHIP
+#ifdef  IPV6_LEAVE_GROUP
+#define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
+#endif
+#endif
+
+static void mdns_mcast_group_ipv4(struct sockaddr_in *ret_sa) {
+    assert(ret_sa);
+
+    memset(ret_sa, 0, sizeof(struct sockaddr_in));
+    ret_sa->sin_family = AF_INET;
+    ret_sa->sin_port = htons(AVAHI_MDNS_PORT);
+    inet_pton(AF_INET, AVAHI_IPV4_MCAST_GROUP, &ret_sa->sin_addr);
+}
+
+static void mdns_mcast_group_ipv6(struct sockaddr_in6 *ret_sa) {
+    assert(ret_sa);
+
+    memset(ret_sa, 0, sizeof(struct sockaddr_in6));
+    ret_sa->sin6_family = AF_INET6;
+    ret_sa->sin6_port = htons(AVAHI_MDNS_PORT);
+    inet_pton(AF_INET6, AVAHI_IPV6_MCAST_GROUP, &ret_sa->sin6_addr);
+}
+
+static void ipv4_address_to_sockaddr(struct sockaddr_in *ret_sa, const AvahiIPv4Address *a, uint16_t port) {
+    assert(ret_sa);
+    assert(a);
+    assert(port > 0);
+
+    memset(ret_sa, 0, sizeof(struct sockaddr_in));
+    ret_sa->sin_family = AF_INET;
+    ret_sa->sin_port = htons(port);
+    memcpy(&ret_sa->sin_addr, a, sizeof(AvahiIPv4Address));
+}
+
+static void ipv6_address_to_sockaddr(struct sockaddr_in6 *ret_sa, const AvahiIPv6Address *a, uint16_t port) {
+    assert(ret_sa);
+    assert(a);
+    assert(port > 0);
+
+    memset(ret_sa, 0, sizeof(struct sockaddr_in6));
+    ret_sa->sin6_family = AF_INET6;
+    ret_sa->sin6_port = htons(port);
+    memcpy(&ret_sa->sin6_addr, a, sizeof(AvahiIPv6Address));
+}
+
+int avahi_mdns_mcast_join_ipv4(int fd, const AvahiIPv4Address *a, int idx, int join) {
+#ifdef HAVE_STRUCT_IP_MREQN
+    struct ip_mreqn mreq;
+#else
+    struct ip_mreq mreq;
+#endif
+    struct sockaddr_in sa;
+
+    assert(fd >= 0);
+    assert(idx >= 0);
+    assert(a);
+
+    memset(&mreq, 0, sizeof(mreq));
+#ifdef HAVE_STRUCT_IP_MREQN
+    mreq.imr_ifindex = idx;
+    mreq.imr_address.s_addr = a->address;
+#else
+    mreq.imr_interface.s_addr = a->address;
+#endif
+    mdns_mcast_group_ipv4(&sa);
+    mreq.imr_multiaddr = sa.sin_addr;
+
+    /* Some network drivers have issues with dropping membership of
+     * mcast groups when the iface is down, but don't allow rejoining
+     * when it comes back up. This is an ugly workaround */
+    if (join)
+        setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
+
+    if (setsockopt(fd, IPPROTO_IP, join ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
+        avahi_log_warn("%s failed: %s", join ? "IP_ADD_MEMBERSHIP" : "IP_DROP_MEMBERSHIP", strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+int avahi_mdns_mcast_join_ipv6(int fd, const AvahiIPv6Address *a, int idx, int join) {
+    struct ipv6_mreq mreq6;
+    struct sockaddr_in6 sa6;
+
+    assert(fd >= 0);
+    assert(idx >= 0);
+    assert(a);
+
+    memset(&mreq6, 0, sizeof(mreq6));
+    mdns_mcast_group_ipv6 (&sa6);
+    mreq6.ipv6mr_multiaddr = sa6.sin6_addr;
+    mreq6.ipv6mr_interface = idx;
+
+    if (join)
+        setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
+
+    if (setsockopt(fd, IPPROTO_IPV6, join ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) {
+        avahi_log_warn("%s failed: %s", join ? "IPV6_ADD_MEMBERSHIP" : "IPV6_DROP_MEMBERSHIP", strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+static int reuseaddr(int fd) {
+    int yes;
+
+    yes = 1;
+    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("SO_REUSEADDR failed: %s", strerror(errno));
+        return -1;
+    }
+
+#ifdef SO_REUSEPORT
+    yes = 1;
+    if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("SO_REUSEPORT failed: %s", strerror(errno));
+        return -1;
+    }
+#endif
+
+    return 0;
+}
+
+static int bind_with_warn(int fd, const struct sockaddr *sa, socklen_t l) {
+
+    assert(fd >= 0);
+    assert(sa);
+    assert(l > 0);
+
+    if (bind(fd, sa, l) < 0) {
+
+        if (errno != EADDRINUSE) {
+            avahi_log_warn("bind() failed: %s", strerror(errno));
+            return -1;
+        }
+
+        avahi_log_warn("*** WARNING: Detected another %s mDNS stack running on this host. This makes mDNS unreliable and is thus not recommended. ***",
+                       sa->sa_family == AF_INET ? "IPv4" : "IPv6");
+
+        /* Try again, this time with SO_REUSEADDR set */
+        if (reuseaddr(fd) < 0)
+            return -1;
+
+        if (bind(fd, sa, l) < 0) {
+            avahi_log_warn("bind() failed: %s", strerror(errno));
+            return -1;
+        }
+    } else {
+
+        /* We enable SO_REUSEADDR afterwards, to make sure that the
+         * user may run other mDNS implementations if he really
+         * wants. */
+
+        if (reuseaddr(fd) < 0)
+            return -1;
+    }
+
+    return 0;
+}
+
+static int ipv4_pktinfo(int fd) {
+    int yes;
+
+#ifdef IP_PKTINFO
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IP_PKTINFO failed: %s", strerror(errno));
+        return -1;
+    }
+#else
+
+#ifdef IP_RECVINTERFACE
+    yes = 1;
+    if (setsockopt (fd, IPPROTO_IP, IP_RECVINTERFACE, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IP_RECVINTERFACE failed: %s", strerror(errno));
+        return -1;
+    }
+#elif defined(IP_RECVIF)
+    yes = 1;
+    if (setsockopt (fd, IPPROTO_IP, IP_RECVIF, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IP_RECVIF failed: %s", strerror(errno));
+        return -1;
+    }
+#endif
+
+#ifdef IP_RECVDSTADDR
+    yes = 1;
+    if (setsockopt (fd, IPPROTO_IP, IP_RECVDSTADDR, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IP_RECVDSTADDR failed: %s", strerror(errno));
+        return -1;
+    }
+#endif
+
+#endif /* IP_PKTINFO */
+
+#ifdef IP_RECVTTL
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IP_RECVTTL failed: %s", strerror(errno));
+        return -1;
+    }
+#endif
+
+    return 0;
+}
+
+static int ipv6_pktinfo(int fd) {
+    int yes;
+
+#ifdef IPV6_RECVPKTINFO
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_RECVPKTINFO failed: %s", strerror(errno));
+        return -1;
+    }
+#elif defined(IPV6_PKTINFO)
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_PKTINFO failed: %s", strerror(errno));
+        return -1;
+    }
+#endif
+
+#ifdef IPV6_RECVHOPS
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPS, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_RECVHOPS failed: %s", strerror(errno));
+        return -1;
+    }
+#elif defined(IPV6_RECVHOPLIMIT)
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_RECVHOPLIMIT failed: %s", strerror(errno));
+        return -1;
+    }
+#elif defined(IPV6_HOPLIMIT)
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_HOPLIMIT, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_HOPLIMIT failed: %s", strerror(errno));
+        return -1;
+    }
+#endif
+
+    return 0;
+}
+
+int avahi_open_socket_ipv4(int no_reuse) {
+    struct sockaddr_in local;
+    int fd = -1, r, ittl;
+    uint8_t ttl, cyes;
+
+    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+        avahi_log_warn("socket() failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    ttl = 255;
+    if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0) {
+        avahi_log_warn("IP_MULTICAST_TTL failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    ittl = 255;
+    if (setsockopt(fd, IPPROTO_IP, IP_TTL, &ittl, sizeof(ittl)) < 0) {
+        avahi_log_warn("IP_TTL failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    cyes = 1;
+    if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &cyes, sizeof(cyes)) < 0) {
+        avahi_log_warn("IP_MULTICAST_LOOP failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    memset(&local, 0, sizeof(local));
+    local.sin_family = AF_INET;
+    local.sin_port = htons(AVAHI_MDNS_PORT);
+
+    if (no_reuse)
+        r = bind(fd, (struct sockaddr*) &local, sizeof(local));
+    else
+        r = bind_with_warn(fd, (struct sockaddr*) &local, sizeof(local));
+
+    if (r < 0)
+        goto fail;
+
+    if (ipv4_pktinfo (fd) < 0)
+         goto fail;
+
+    if (avahi_set_cloexec(fd) < 0) {
+        avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (avahi_set_nonblock(fd) < 0) {
+        avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    return fd;
+
+fail:
+    if (fd >= 0)
+        close(fd);
+
+    return -1;
+}
+
+int avahi_open_socket_ipv6(int no_reuse) {
+    struct sockaddr_in6 sa, local;
+    int fd = -1, yes, r;
+    int ttl;
+
+    mdns_mcast_group_ipv6(&sa);
+
+    if ((fd = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
+        avahi_log_warn("socket() failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    ttl = 255;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0) {
+        avahi_log_warn("IPV6_MULTICAST_HOPS failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    ttl = 255;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)) < 0) {
+        avahi_log_warn("IPV6_UNICAST_HOPS failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_V6ONLY failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_MULTICAST_LOOP failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    memset(&local, 0, sizeof(local));
+    local.sin6_family = AF_INET6;
+    local.sin6_port = htons(AVAHI_MDNS_PORT);
+
+    if (no_reuse)
+        r = bind(fd, (struct sockaddr*) &local, sizeof(local));
+    else
+        r = bind_with_warn(fd, (struct sockaddr*) &local, sizeof(local));
+
+    if (r < 0)
+        goto fail;
+
+    if (ipv6_pktinfo(fd) < 0)
+        goto fail;
+
+    if (avahi_set_cloexec(fd) < 0) {
+        avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (avahi_set_nonblock(fd) < 0) {
+        avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    return fd;
+
+fail:
+    if (fd >= 0)
+        close(fd);
+
+    return -1;
+}
+
+static int sendmsg_loop(int fd, struct msghdr *msg, int flags) {
+    assert(fd >= 0);
+    assert(msg);
+
+    for (;;) {
+
+        if (sendmsg(fd, msg, flags) >= 0)
+            break;
+
+        if (errno == EINTR)
+            continue;
+
+        if (errno != EAGAIN) {
+            char where[64];
+            struct sockaddr_in *sin = msg->msg_name;
+
+            inet_ntop(sin->sin_family, &sin->sin_addr, where, sizeof(where));
+            avahi_log_debug("sendmsg() to %s failed: %s", where, strerror(errno));
+            return -1;
+        }
+
+        if (avahi_wait_for_write(fd) < 0)
+            return -1;
+    }
+
+    return 0;
+}
+
+int avahi_send_dns_packet_ipv4(
+        int fd,
+        AvahiIfIndex interface,
+        AvahiDnsPacket *p,
+        const AvahiIPv4Address *src_address,
+        const AvahiIPv4Address *dst_address,
+        uint16_t dst_port) {
+
+    struct sockaddr_in sa;
+    struct msghdr msg;
+    struct iovec io;
+#ifdef IP_PKTINFO
+    struct cmsghdr *cmsg;
+    size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
+#elif !defined(IP_MULTICAST_IF) && defined(IP_SENDSRCADDR)
+    struct cmsghdr *cmsg;
+    size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_addr)) / sizeof(size_t)) + 1];
+#endif
+
+    assert(fd >= 0);
+    assert(p);
+    assert(avahi_dns_packet_check_valid(p) >= 0);
+    assert(!dst_address || dst_port > 0);
+
+    if (!dst_address)
+        mdns_mcast_group_ipv4(&sa);
+    else
+        ipv4_address_to_sockaddr(&sa, dst_address, dst_port);
+
+    memset(&io, 0, sizeof(io));
+    io.iov_base = AVAHI_DNS_PACKET_DATA(p);
+    io.iov_len = p->size;
+
+    memset(&msg, 0, sizeof(msg));
+    msg.msg_name = &sa;
+    msg.msg_namelen = sizeof(sa);
+    msg.msg_iov = &io;
+    msg.msg_iovlen = 1;
+    msg.msg_flags = 0;
+    msg.msg_control = NULL;
+    msg.msg_controllen = 0;
+
+#ifdef IP_PKTINFO
+    if (interface > 0 || src_address) {
+        struct in_pktinfo *pkti;
+
+        memset(cmsg_data, 0, sizeof(cmsg_data));
+        msg.msg_control = cmsg_data;
+        msg.msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo));
+
+        cmsg = CMSG_FIRSTHDR(&msg);
+        cmsg->cmsg_len = msg.msg_controllen;
+        cmsg->cmsg_level = IPPROTO_IP;
+        cmsg->cmsg_type = IP_PKTINFO;
+
+        pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
+
+        if (interface > 0)
+            pkti->ipi_ifindex = interface;
+
+        if (src_address)
+            pkti->ipi_spec_dst.s_addr = src_address->address;
+    }
+#elif defined(IP_MULTICAST_IF)
+    if (src_address) {
+        struct in_addr any = { INADDR_ANY };
+        if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, src_address ? &src_address->address : &any, sizeof(struct in_addr)) < 0) {
+            avahi_log_warn("IP_MULTICAST_IF failed: %s", strerror(errno));
+            return -1;
+        }
+    }
+#elif defined(IP_SENDSRCADDR)
+    if (src_address) {
+        struct in_addr *addr;
+
+        memset(cmsg_data, 0, sizeof(cmsg_data));
+        msg.msg_control = cmsg_data;
+        msg.msg_controllen = CMSG_LEN(sizeof(struct in_addr));
+
+        cmsg = CMSG_FIRSTHDR(&msg);
+        cmsg->cmsg_len = msg.msg_controllen;
+        cmsg->cmsg_level = IPPROTO_IP;
+        cmsg->cmsg_type = IP_SENDSRCADDR;
+
+        addr = (struct in_addr *)CMSG_DATA(cmsg);
+        addr->s_addr =  src_address->address;
+    }
+#elif defined(__GNUC__)
+#warning "FIXME: We need some code to set the outgoing interface/local address here if IP_PKTINFO/IP_MULTICAST_IF is not available"
+#endif
+
+    return sendmsg_loop(fd, &msg, 0);
+}
+
+int avahi_send_dns_packet_ipv6(
+        int fd,
+        AvahiIfIndex interface,
+        AvahiDnsPacket *p,
+        const AvahiIPv6Address *src_address,
+        const AvahiIPv6Address *dst_address,
+        uint16_t dst_port) {
+
+    struct sockaddr_in6 sa;
+    struct msghdr msg;
+    struct iovec io;
+    struct cmsghdr *cmsg;
+    size_t cmsg_data[(CMSG_SPACE(sizeof(struct in6_pktinfo))/sizeof(size_t)) + 1];
+
+    assert(fd >= 0);
+    assert(p);
+    assert(avahi_dns_packet_check_valid(p) >= 0);
+    assert(!dst_address || dst_port > 0);
+
+    if (!dst_address)
+        mdns_mcast_group_ipv6(&sa);
+    else
+        ipv6_address_to_sockaddr(&sa, dst_address, dst_port);
+
+    memset(&io, 0, sizeof(io));
+    io.iov_base = AVAHI_DNS_PACKET_DATA(p);
+    io.iov_len = p->size;
+
+    memset(&msg, 0, sizeof(msg));
+    msg.msg_name = &sa;
+    msg.msg_namelen = sizeof(sa);
+    msg.msg_iov = &io;
+    msg.msg_iovlen = 1;
+    msg.msg_flags = 0;
+
+    if (interface > 0 || src_address) {
+        struct in6_pktinfo *pkti;
+
+        memset(cmsg_data, 0, sizeof(cmsg_data));
+        msg.msg_control = cmsg_data;
+        msg.msg_controllen = CMSG_LEN(sizeof(struct in6_pktinfo));
+
+        cmsg = CMSG_FIRSTHDR(&msg);
+        cmsg->cmsg_len = msg.msg_controllen;
+        cmsg->cmsg_level = IPPROTO_IPV6;
+        cmsg->cmsg_type = IPV6_PKTINFO;
+
+        pkti = (struct in6_pktinfo*) CMSG_DATA(cmsg);
+
+        if (interface > 0)
+            pkti->ipi6_ifindex = interface;
+
+        if (src_address)
+            memcpy(&pkti->ipi6_addr, src_address->address, sizeof(src_address->address));
+    } else {
+        msg.msg_control = NULL;
+        msg.msg_controllen = 0;
+    }
+
+    return sendmsg_loop(fd, &msg, 0);
+}
+
+AvahiDnsPacket *avahi_recv_dns_packet_ipv4(
+        int fd,
+        AvahiIPv4Address *ret_src_address,
+        uint16_t *ret_src_port,
+        AvahiIPv4Address *ret_dst_address,
+        AvahiIfIndex *ret_iface,
+        uint8_t *ret_ttl) {
+
+    AvahiDnsPacket *p= NULL;
+    struct msghdr msg;
+    struct iovec io;
+    size_t aux[1024 / sizeof(size_t)]; /* for alignment on ia64 ! */
+    ssize_t l;
+    struct cmsghdr *cmsg;
+    int found_addr = 0;
+    int ms;
+    struct sockaddr_in sa;
+
+    assert(fd >= 0);
+
+    if (ioctl(fd, FIONREAD, &ms) < 0) {
+        avahi_log_warn("ioctl(): %s", strerror(errno));
+        goto fail;
+    }
+
+    if (ms < 0) {
+        avahi_log_warn("FIONREAD returned negative value.");
+        goto fail;
+    }
+
+    p = avahi_dns_packet_new(ms + AVAHI_DNS_PACKET_EXTRA_SIZE);
+
+    io.iov_base = AVAHI_DNS_PACKET_DATA(p);
+    io.iov_len = p->max_size;
+
+    memset(&msg, 0, sizeof(msg));
+    msg.msg_name = &sa;
+    msg.msg_namelen = sizeof(sa);
+    msg.msg_iov = &io;
+    msg.msg_iovlen = 1;
+    msg.msg_control = aux;
+    msg.msg_controllen = sizeof(aux);
+    msg.msg_flags = 0;
+
+    if ((l = recvmsg(fd, &msg, 0)) < 0) {
+        /* Linux returns EAGAIN when an invalid IP packet has been
+        received. We suppress warnings in this case because this might
+        create quite a bit of log traffic on machines with unstable
+        links. (See #60) */
+
+        if (errno != EAGAIN)
+            avahi_log_warn("recvmsg(): %s", strerror(errno));
+
+        goto fail;
+    }
+
+    /* For corrupt packets FIONREAD returns zero size (See rhbz #607297). So
+     * fail after having read them. */
+    if (!ms)
+        goto fail;
+
+    if (sa.sin_addr.s_addr == INADDR_ANY)
+        /* Linux 2.4 behaves very strangely sometimes! */
+        goto fail;
+
+    assert(!(msg.msg_flags & MSG_CTRUNC));
+    assert(!(msg.msg_flags & MSG_TRUNC));
+
+    p->size = (size_t) l;
+
+    if (ret_src_port)
+        *ret_src_port = avahi_port_from_sockaddr((struct sockaddr*) &sa);
+
+    if (ret_src_address) {
+        AvahiAddress a;
+        avahi_address_from_sockaddr((struct sockaddr*) &sa, &a);
+        *ret_src_address = a.data.ipv4;
+    }
+
+    if (ret_ttl)
+        *ret_ttl = 255;
+
+    if (ret_iface)
+        *ret_iface = AVAHI_IF_UNSPEC;
+
+    for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+
+        if (cmsg->cmsg_level == IPPROTO_IP) {
+
+            switch (cmsg->cmsg_type) {
+#ifdef IP_RECVTTL
+                case IP_RECVTTL:
+#endif
+                case IP_TTL:
+                    if (ret_ttl)
+                        *ret_ttl = (uint8_t) (*(int *) CMSG_DATA(cmsg));
+
+                    break;
+
+#ifdef IP_PKTINFO
+                case IP_PKTINFO: {
+                    struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg);
+
+                    if (ret_iface && i->ipi_ifindex > 0)
+                        *ret_iface = (int) i->ipi_ifindex;
+
+                    if (ret_dst_address)
+                        ret_dst_address->address = i->ipi_addr.s_addr;
+
+                    found_addr = 1;
+
+                    break;
+                }
+#endif
+
+#ifdef IP_RECVIF
+                case IP_RECVIF: {
+                    struct sockaddr_dl *sdl = (struct sockaddr_dl *) CMSG_DATA (cmsg);
+
+                    if (ret_iface) {
+#ifdef __sun
+                        if (*(uint_t*) sdl > 0)
+                            *ret_iface = *(uint_t*) sdl;
+#else
+
+                        if (sdl->sdl_index > 0)
+                            *ret_iface = (int) sdl->sdl_index;
+#endif
+                    }
+
+                    break;
+                }
+#endif
+
+#ifdef IP_RECVDSTADDR
+                case IP_RECVDSTADDR:
+                    if (ret_dst_address)
+                        memcpy(&ret_dst_address->address, CMSG_DATA (cmsg), 4);
+
+                    found_addr = 1;
+                    break;
+#endif
+
+                default:
+                    avahi_log_warn("Unhandled cmsg_type: %d", cmsg->cmsg_type);
+                    break;
+            }
+        }
+    }
+
+    assert(found_addr);
+
+    return p;
+
+fail:
+    if (p)
+        avahi_dns_packet_free(p);
+
+    return NULL;
+}
+
+AvahiDnsPacket *avahi_recv_dns_packet_ipv6(
+        int fd,
+        AvahiIPv6Address *ret_src_address,
+        uint16_t *ret_src_port,
+        AvahiIPv6Address *ret_dst_address,
+        AvahiIfIndex *ret_iface,
+        uint8_t *ret_ttl) {
+
+    AvahiDnsPacket *p = NULL;
+    struct msghdr msg;
+    struct iovec io;
+    size_t aux[1024 / sizeof(size_t)];
+    ssize_t l;
+    int ms;
+    struct cmsghdr *cmsg;
+    int found_ttl = 0, found_iface = 0;
+    struct sockaddr_in6 sa;
+
+    assert(fd >= 0);
+
+    if (ioctl(fd, FIONREAD, &ms) < 0) {
+        avahi_log_warn("ioctl(): %s", strerror(errno));
+        goto fail;
+    }
+
+    if (ms < 0) {
+        avahi_log_warn("FIONREAD returned negative value.");
+        goto fail;
+    }
+
+    p = avahi_dns_packet_new(ms + AVAHI_DNS_PACKET_EXTRA_SIZE);
+
+    io.iov_base = AVAHI_DNS_PACKET_DATA(p);
+    io.iov_len = p->max_size;
+
+    memset(&msg, 0, sizeof(msg));
+    msg.msg_name = (struct sockaddr*) &sa;
+    msg.msg_namelen = sizeof(sa);
+
+    msg.msg_iov = &io;
+    msg.msg_iovlen = 1;
+    msg.msg_control = aux;
+    msg.msg_controllen = sizeof(aux);
+    msg.msg_flags = 0;
+
+    if ((l = recvmsg(fd, &msg, 0)) < 0) {
+        /* Linux returns EAGAIN when an invalid IP packet has been
+        received. We suppress warnings in this case because this might
+        create quite a bit of log traffic on machines with unstable
+        links. (See #60) */
+
+        if (errno != EAGAIN)
+            avahi_log_warn("recvmsg(): %s", strerror(errno));
+
+        goto fail;
+    }
+
+    /* For corrupt packets FIONREAD returns zero size (See rhbz #607297). So
+     * fail after having read them. */
+    if (!ms)
+        goto fail;
+
+    assert(!(msg.msg_flags & MSG_CTRUNC));
+    assert(!(msg.msg_flags & MSG_TRUNC));
+
+    p->size = (size_t) l;
+
+    if (ret_src_port)
+        *ret_src_port = avahi_port_from_sockaddr((struct sockaddr*) &sa);
+
+    if (ret_src_address) {
+        AvahiAddress a;
+        avahi_address_from_sockaddr((struct sockaddr*) &sa, &a);
+        *ret_src_address = a.data.ipv6;
+    }
+
+    for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
+
+        if (cmsg->cmsg_level == IPPROTO_IPV6) {
+
+            switch (cmsg->cmsg_type) {
+
+                case IPV6_HOPLIMIT:
+
+                    if (ret_ttl)
+                        *ret_ttl = (uint8_t) (*(int *) CMSG_DATA(cmsg));
+
+                    found_ttl = 1;
+
+                    break;
+
+                case IPV6_PKTINFO: {
+                    struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg);
+
+                    if (ret_iface && i->ipi6_ifindex > 0)
+                        *ret_iface = i->ipi6_ifindex;
+
+                    if (ret_dst_address)
+                        memcpy(ret_dst_address->address, i->ipi6_addr.s6_addr, 16);
+
+                    found_iface = 1;
+                    break;
+                }
+
+                default:
+                    avahi_log_warn("Unhandled cmsg_type: %d", cmsg->cmsg_type);
+                    break;
+            }
+        }
+    }
+
+    assert(found_iface);
+    assert(found_ttl);
+
+    return p;
+
+fail:
+    if (p)
+        avahi_dns_packet_free(p);
+
+    return NULL;
+}
+
+int avahi_open_unicast_socket_ipv4(void) {
+    struct sockaddr_in local;
+    int fd = -1;
+
+    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+        avahi_log_warn("socket() failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    memset(&local, 0, sizeof(local));
+    local.sin_family = AF_INET;
+
+    if (bind(fd, (struct sockaddr*) &local, sizeof(local)) < 0) {
+        avahi_log_warn("bind() failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (ipv4_pktinfo(fd) < 0) {
+         goto fail;
+    }
+
+    if (avahi_set_cloexec(fd) < 0) {
+        avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (avahi_set_nonblock(fd) < 0) {
+        avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    return fd;
+
+fail:
+    if (fd >= 0)
+        close(fd);
+
+    return -1;
+}
+
+int avahi_open_unicast_socket_ipv6(void) {
+    struct sockaddr_in6 local;
+    int fd = -1, yes;
+
+    if ((fd = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
+        avahi_log_warn("socket() failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    yes = 1;
+    if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &yes, sizeof(yes)) < 0) {
+        avahi_log_warn("IPV6_V6ONLY failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    memset(&local, 0, sizeof(local));
+    local.sin6_family = AF_INET6;
+
+    if (bind(fd, (struct sockaddr*) &local, sizeof(local)) < 0) {
+        avahi_log_warn("bind() failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (ipv6_pktinfo(fd) < 0)
+        goto fail;
+
+    if (avahi_set_cloexec(fd) < 0) {
+        avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    if (avahi_set_nonblock(fd) < 0) {
+        avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));
+        goto fail;
+    }
+
+    return fd;
+
+fail:
+    if (fd >= 0)
+        close(fd);
+
+    return -1;
+}