ssize_t
Recvfrom_flags(int fd, void *ptr, size_t nbytes, int *flagsp,
SA *sa, socklen_t *salenptr, void *dstaddrp)
{
ssize_t n;
n = recvfrom_flags(fd, ptr, nbytes, flagsp, sa, salenptr, dstaddrp);
if (n < 0)
err_quit("recvfrom_flags error");
return(n);
}
// This routine is called when the main loop detects that data is available on a socket.
static void SocketDataReady(mDNS *const m, PosixNetworkInterface *intf, int skt)
{
mDNSAddr senderAddr, destAddr;
mDNSIPPort senderPort;
ssize_t packetLen;
DNSMessage packet;
struct my_in_pktinfo packetInfo;
struct sockaddr_storage from;
socklen_t fromLen;
int flags;
mDNSBool reject;
assert(m != NULL);
assert(intf != NULL);
assert(skt >= 0);
fromLen = sizeof(from);
flags = 0;
packetLen = recvfrom_flags(skt, &packet, sizeof(packet), &flags, (struct sockaddr *) &from, &fromLen, &packetInfo);
if (packetLen >= 0)
{
SockAddrTomDNSAddr((struct sockaddr*)&from, &senderAddr, &senderPort);
SockAddrTomDNSAddr((struct sockaddr*)&packetInfo.ipi_addr, &destAddr, NULL);
// If we have broken IP_RECVDSTADDR functionality (so far
// I've only seen this on OpenBSD) then apply a hack to
// convince mDNS Core that this isn't a spoof packet.
// Basically what we do is check to see whether the
// packet arrived as a multicast and, if so, set its
// destAddr to the mDNS address.
//
// I must admit that I could just be doing something
// wrong on OpenBSD and hence triggering this problem
// but I'm at a loss as to how.
//
// If this platform doesn't have IP_PKTINFO or IP_RECVDSTADDR, then we have
// no way to tell the destination address or interface this packet arrived on,
// so all we can do is just assume it's a multicast
#if HAVE_BROKEN_RECVDSTADDR || (!defined(IP_PKTINFO) && !defined(IP_RECVDSTADDR))
if ( (destAddr.NotAnInteger == 0) && (flags & MSG_MCAST) )
{
destAddr.type == senderAddr.type;
if (senderAddr.type == mDNSAddrType_IPv4) destAddr.ip.v4 = AllDNSLinkGroup;
else if (senderAddr.type == mDNSAddrType_IPv6) destAddr.ip.v6 = AllDNSLinkGroupv6;
}
#endif
// We only accept the packet if the interface on which it came
// in matches the interface associated with this socket.
// We do this match by name or by index, depending on which
// information is available. recvfrom_flags sets the name
// to "" if the name isn't available, or the index to -1
// if the index is available. This accomodates the various
// different capabilities of our target platforms.
reject = mDNSfalse;
if ( packetInfo.ipi_ifname[0] != 0 ) reject = (strcmp(packetInfo.ipi_ifname, intf->intfName) != 0);
else if ( packetInfo.ipi_ifindex != -1 ) reject = (packetInfo.ipi_ifindex != intf->index);
if (reject)
{
verbosedebugf("SocketDataReady ignored a packet from %#a to %#a on interface %s/%d expecting %#a/%s/%d",
&senderAddr, &destAddr, packetInfo.ipi_ifname, packetInfo.ipi_ifindex,
&intf->coreIntf.ip, intf->intfName, intf->index);
packetLen = -1;
num_pkts_rejected++;
if (num_pkts_rejected > (num_pkts_accepted + 1) * (num_registered_interfaces + 1) * 2)
{
fprintf(stderr,
"*** WARNING: Received %d packets; Accepted %d packets; Rejected %d packets because of interface mismatch\n",
num_pkts_accepted + num_pkts_rejected, num_pkts_accepted, num_pkts_rejected);
num_pkts_accepted = 0;
num_pkts_rejected = 0;
}
}
else
{
verbosedebugf("SocketDataReady got a packet from %#a to %#a on interface %#a/%s/%d",
&senderAddr, &destAddr, &intf->coreIntf.ip, intf->intfName, intf->index);
num_pkts_accepted++;
}
}
if (packetLen >= 0 && packetLen < (ssize_t)sizeof(DNSMessageHeader))
{
debugf("SocketDataReady packet length (%d) too short", packetLen);
packetLen = -1;
}
if (packetLen >= 0)
mDNSCoreReceive(m, &packet, (mDNSu8 *)&packet + packetLen,
&senderAddr, senderPort, &destAddr, MulticastDNSPort, intf->coreIntf.InterfaceID, 255);
}
