mDNSexport void ExampleClientEventLoop(mDNS *const m)
{
signal(SIGINT, HandleSIG); // SIGINT is what you get for a Ctrl-C
signal(SIGTERM, HandleSIG);
while (!StopNow)
{
int nfds = 0;
fd_set readfds;
struct timeval timeout;
int result;
// 1. Set up the fd_set as usual here.
// This example client has no file descriptors of its own,
// but a real application would call FD_SET to add them to the set here
FD_ZERO(&readfds);
// 2. Set up the timeout.
// This example client has no other work it needs to be doing,
// so we set an effectively infinite timeout
timeout.tv_sec = 0x3FFFFFFF;
timeout.tv_usec = 0;
// 3. Give the mDNSPosix layer a chance to add its information to the fd_set and timeout
mDNSPosixGetFDSet(m, &nfds, &readfds, &timeout);
// 4. Call select as normal
verbosedebugf("select(%d, %d.%06d)", nfds, timeout.tv_sec, timeout.tv_usec);
result = select(nfds, &readfds, NULL, NULL, &timeout);
if (result < 0)
{
verbosedebugf("select() returned %d errno %d", result, errno);
if (errno != EINTR) StopNow = mDNStrue;
}
else
{
// 5. Call mDNSPosixProcessFDSet to let the mDNSPosix layer do its work
mDNSPosixProcessFDSet(m, &readfds);
// 6. This example client has no other work it needs to be doing,
// but a real client would do its work here
// ... (do work) ...
}
}
debugf("Exiting");
}
static void SockAddrTomDNSAddr(const struct sockaddr *const sa, mDNSAddr *ipAddr, mDNSIPPort *ipPort)
{
switch (sa->sa_family)
{
case AF_INET:
{
struct sockaddr_in* sin = (struct sockaddr_in*)sa;
ipAddr->type = mDNSAddrType_IPv4;
ipAddr->ip.v4.NotAnInteger = sin->sin_addr.s_addr;
if (ipPort) ipPort->NotAnInteger = sin->sin_port;
break;
}
#ifdef mDNSIPv6Support
case AF_INET6:
{
struct sockaddr_in6* sin6 = (struct sockaddr_in6*)sa;
assert(sin6->sin6_len == sizeof(*sin6));
ipAddr->type = mDNSAddrType_IPv6;
ipAddr->ip.v6 = *(mDNSv6Addr*)&sin6->sin6_addr;
if (ipPort) ipPort->NotAnInteger = sin6->sin6_port;
break;
}
#endif
default:
verbosedebugf("SockAddrTomDNSAddr: Uknown address family %d\n", sa->sa_family);
ipAddr->type = mDNSAddrType_None;
if (ipPort) ipPort->NotAnInteger = 0;
break;
}
}
mDNSlocal int NSEC3SameName(const mDNSu8 *name, int namelen, const mDNSu8 *nsecName, int nsecLen)
{
int i;
// Note: With NSEC3, the lengths should always be same.
if (namelen != nsecLen)
{
LogMsg("NSEC3SameName: ERROR!! namelen %d, nsecLen %d", namelen, nsecLen);
return ((namelen < nsecLen) ? -1 : 1);
}
for (i = 0; i < namelen; i++)
{
mDNSu8 ac = *name++;
mDNSu8 bc = *nsecName++;
if (mDNSIsUpperCase(ac)) ac += 'a' - 'A';
if (mDNSIsUpperCase(bc)) bc += 'a' - 'A';
if (ac != bc)
{
verbosedebugf("NSEC3SameName: returning ac %c, bc %c", ac, bc);
return ((ac < bc) ? -1 : 1);
}
}
return 0;
}
// mDNS core calls this routine when it needs to send a packet.
mDNSexport mStatus mDNSPlatformSendUDP(const mDNS *const m, const DNSMessage *const msg, const mDNSu8 *const end,
mDNSInterfaceID InterfaceID, mDNSIPPort srcPort, const mDNSAddr *dst, mDNSIPPort dstPort)
{
int err;
struct sockaddr_storage to;
PosixNetworkInterface * thisIntf;
assert(m != NULL);
assert(msg != NULL);
assert(end != NULL);
assert( (((char *) end) - ((char *) msg)) > 0 );
assert(InterfaceID != 0); // Can't send from zero source address
assert(srcPort.NotAnInteger != 0); // Nor from a zero source port
assert(dstPort.NotAnInteger != 0); // Nor from a zero source port
if (dst->type == mDNSAddrType_IPv4)
{
struct sockaddr_in *sin = (struct sockaddr_in*)&to;
#ifndef NOT_HAVE_SA_LEN
sin->sin_len = sizeof(*sin);
#endif
sin->sin_family = AF_INET;
sin->sin_port = dstPort.NotAnInteger;
sin->sin_addr.s_addr = dst->ip.v4.NotAnInteger;
}
#ifdef mDNSIPv6Support
else if (dst->type == mDNSAddrType_IPv6)
{
struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)&to;
mDNSPlatformMemZero(sin6, sizeof(*sin6));
sin6->sin6_len = sizeof(*sin6);
sin6->sin6_family = AF_INET6;
sin6->sin6_port = dstPort.NotAnInteger;
sin6->sin6_addr = *(struct in6_addr*)&dst->ip.v6;
}
#endif
err = 0;
thisIntf = (PosixNetworkInterface *)(InterfaceID);
if (dst->type == mDNSAddrType_IPv4)
err = sendto(thisIntf->multicastSocket, msg, (char*)end - (char*)msg, 0, (struct sockaddr *)&to, GET_SA_LEN(to));
#ifdef mDNSIPv6Support
else if (dst->type == mDNSAddrType_IPv6)
err = sendto(thisIntf->multicastSocketv6, msg, (char*)end - (char*)msg, 0, (struct sockaddr *)&to, GET_SA_LEN(to));
#endif
if (err > 0) err = 0;
else if (err < 0)
verbosedebugf("mDNSPlatformSendUDP got error %d (%s) sending packet to %#a on interface %#a/%s/%d",
errno, strerror(errno), dst, &thisIntf->coreIntf.ip, thisIntf->intfName, thisIntf->index);
return PosixErrorToStatus(err);
}
// Sets up a multicast send/receive socket for the specified
// port on the interface specified by the IP addrelss intfAddr.
static int SetupSocket(struct sockaddr *intfAddr, mDNSIPPort port, int interfaceIndex, int *sktPtr)
{
int err = 0;
static const int kOn = 1;
static const int kIntTwoFiveFive = 255;
static const unsigned char kByteTwoFiveFive = 255;
(void) interfaceIndex; // Unused
assert(intfAddr != NULL);
assert(sktPtr != NULL);
assert(*sktPtr == -1);
// Open the socket...
if (intfAddr->sa_family == AF_INET) *sktPtr = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
#ifdef mDNSIPv6Support
else if (intfAddr->sa_family == AF_INET6) *sktPtr = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
#endif
else return EINVAL;
if (*sktPtr < 0) { err = errno; perror("socket"); }
// ... with a shared UDP port
if (err == 0)
{
#if defined(SO_REUSEPORT)
err = setsockopt(*sktPtr, SOL_SOCKET, SO_REUSEPORT, &kOn, sizeof(kOn));
#elif defined(SO_REUSEADDR)
err = setsockopt(*sktPtr, SOL_SOCKET, SO_REUSEADDR, &kOn, sizeof(kOn));
#else
#error This platform has no way to avoid address busy errors on multicast.
#endif
if (err < 0) { err = errno; perror("setsockopt - SO_REUSExxxx"); }
}
// We want to receive destination addresses and interface identifiers.
if (intfAddr->sa_family == AF_INET)
{
struct ip_mreq imr;
struct sockaddr_in bindAddr;
if (err == 0)
{
#if defined(IP_PKTINFO) // Linux
err = setsockopt(*sktPtr, IPPROTO_IP, IP_PKTINFO, &kOn, sizeof(kOn));
if (err < 0) { err = errno; perror("setsockopt - IP_PKTINFO"); }
#elif defined(IP_RECVDSTADDR) || defined(IP_RECVIF) // BSD and Solaris
#if defined(IP_RECVDSTADDR)
err = setsockopt(*sktPtr, IPPROTO_IP, IP_RECVDSTADDR, &kOn, sizeof(kOn));
if (err < 0) { err = errno; perror("setsockopt - IP_RECVDSTADDR"); }
#endif
#if defined(IP_RECVIF)
if (err == 0)
{
err = setsockopt(*sktPtr, IPPROTO_IP, IP_RECVIF, &kOn, sizeof(kOn));
if (err < 0) { err = errno; perror("setsockopt - IP_RECVIF"); }
}
#endif
#else
#warning This platform has no way to get the destination interface information -- will only work for single-homed hosts
#endif
}
// Add multicast group membership on this interface
if (err == 0)
{
imr.imr_multiaddr.s_addr = AllDNSLinkGroup.NotAnInteger;
imr.imr_interface = ((struct sockaddr_in*)intfAddr)->sin_addr;
err = setsockopt(*sktPtr, IPPROTO_IP, IP_ADD_MEMBERSHIP, &imr, sizeof(imr));
if (err < 0) { err = errno; perror("setsockopt - IP_ADD_MEMBERSHIP"); }
}
// Specify outgoing interface too
if (err == 0)
{
err = setsockopt(*sktPtr, IPPROTO_IP, IP_MULTICAST_IF, &((struct sockaddr_in*)intfAddr)->sin_addr, sizeof(struct in_addr));
if (err < 0) { err = errno; perror("setsockopt - IP_MULTICAST_IF"); }
}
// Per the mDNS spec, send unicast packets with TTL 255
if (err == 0)
{
err = setsockopt(*sktPtr, IPPROTO_IP, IP_TTL, &kIntTwoFiveFive, sizeof(kIntTwoFiveFive));
if (err < 0) { err = errno; perror("setsockopt - IP_TTL"); }
}
// and multicast packets with TTL 255 too
// There's some debate as to whether IP_MULTICAST_TTL is an int or a byte so we just try both.
if (err == 0)
{
err = setsockopt(*sktPtr, IPPROTO_IP, IP_MULTICAST_TTL, &kByteTwoFiveFive, sizeof(kByteTwoFiveFive));
if (err < 0 && errno == EINVAL)
err = setsockopt(*sktPtr, IPPROTO_IP, IP_MULTICAST_TTL, &kIntTwoFiveFive, sizeof(kIntTwoFiveFive));
if (err < 0) { err = errno; perror("setsockopt - IP_MULTICAST_TTL"); }
}
// And start listening for packets
if (err == 0)
{
bindAddr.sin_family = AF_INET;
bindAddr.sin_port = port.NotAnInteger;
bindAddr.sin_addr.s_addr = INADDR_ANY; // Want to receive multicasts AND unicasts on this socket
err = bind(*sktPtr, (struct sockaddr *) &bindAddr, sizeof(bindAddr));
if (err < 0) { err = errno; perror("bind"); fflush(stderr); }
}
} // endif (intfAddr->sa_family == AF_INET)
#ifdef mDNSIPv6Support
else if (intfAddr->sa_family == AF_INET6)
{
struct ipv6_mreq imr6;
struct sockaddr_in6 bindAddr6;
if (err == 0)
{
#if defined(IPV6_PKTINFO)
err = setsockopt(*sktPtr, IPPROTO_IPV6, IPV6_PKTINFO, &kOn, sizeof(kOn));
if (err < 0) { err = errno; perror("setsockopt - IPV6_PKTINFO"); }
#else
#warning This platform has no way to get the destination interface information for IPv6 -- will only work for single-homed hosts
#endif
}
// Add multicast group membership on this interface
if (err == 0)
{
imr6.ipv6mr_multiaddr = *(const struct in6_addr*)&AllDNSLinkGroupv6;
imr6.ipv6mr_interface = interfaceIndex;
err = setsockopt(*sktPtr, IPPROTO_IPV6, IPV6_JOIN_GROUP, &imr6, sizeof(imr6));
if (err < 0)
{
err = errno;
verbosedebugf("IPV6_JOIN_GROUP %.16a on %d failed.\n", &imr6.ipv6mr_multiaddr, imr6.ipv6mr_interface);
perror("setsockopt - IPV6_JOIN_GROUP");
}
}
// Specify outgoing interface too
if (err == 0)
{
u_int multicast_if = interfaceIndex;
err = setsockopt(*sktPtr, IPPROTO_IPV6, IPV6_MULTICAST_IF, &multicast_if, sizeof(multicast_if));
if (err < 0) { err = errno; perror("setsockopt - IPV6_MULTICAST_IF"); }
}
// We want to receive only IPv6 packets on this socket.
// Without this option, we may get IPv4 addresses as mapped addresses.
if (err == 0)
{
err = setsockopt(*sktPtr, IPPROTO_IPV6, IPV6_V6ONLY, &kOn, sizeof(kOn));
if (err < 0) { err = errno; perror("setsockopt - IPV6_V6ONLY"); }
}
// Per the mDNS spec, send unicast packets with TTL 255
if (err == 0)
{
err = setsockopt(*sktPtr, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &kIntTwoFiveFive, sizeof(kIntTwoFiveFive));
if (err < 0) { err = errno; perror("setsockopt - IPV6_UNICAST_HOPS"); }
}
// and multicast packets with TTL 255 too
// There's some debate as to whether IPV6_MULTICAST_HOPS is an int or a byte so we just try both.
if (err == 0)
{
err = setsockopt(*sktPtr, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &kByteTwoFiveFive, sizeof(kByteTwoFiveFive));
if (err < 0 && errno == EINVAL)
err = setsockopt(*sktPtr, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &kIntTwoFiveFive, sizeof(kIntTwoFiveFive));
if (err < 0) { err = errno; perror("setsockopt - IPV6_MULTICAST_HOPS"); }
}
// And start listening for packets
if (err == 0)
{
mDNSPlatformMemZero(&bindAddr6, sizeof(bindAddr6));
bindAddr6.sin6_len = sizeof(bindAddr6);
bindAddr6.sin6_family = AF_INET6;
bindAddr6.sin6_port = port.NotAnInteger;
bindAddr6.sin6_flowinfo = 0;
// bindAddr6.sin6_addr.s_addr = IN6ADDR_ANY_INIT; // Want to receive multicasts AND unicasts on this socket
bindAddr6.sin6_scope_id = 0;
err = bind(*sktPtr, (struct sockaddr *) &bindAddr6, sizeof(bindAddr6));
if (err < 0) { err = errno; perror("bind"); fflush(stderr); }
}
} // endif (intfAddr->sa_family == AF_INET6)
#endif
// Set the socket to non-blocking.
if (err == 0)
{
err = fcntl(*sktPtr, F_GETFL, 0);
if (err < 0) err = errno;
else
{
err = fcntl(*sktPtr, F_SETFL, err | O_NONBLOCK);
if (err < 0) err = errno;
}
}
// Clean up
if (err != 0 && *sktPtr != -1) { assert(close(*sktPtr) == 0); *sktPtr = -1; }
assert( (err == 0) == (*sktPtr != -1) );
return err;
}
// 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);
}
int main(int argc, char **argv)
{
mStatus status;
int result;
// Parse our command line arguments. This won't come back if there's an error.
ParseArguments(argc, argv);
// If we're told to run as a daemon, then do that straight away.
// Note that we don't treat the inability to create our PID
// file as an error. Also note that we assign getpid to a long
// because printf has no format specified for pid_t.
if (gDaemon) {
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr, "%s: Starting in daemon mode\n", gProgramName);
}
daemon(0,0);
{
FILE *fp;
int junk;
fp = fopen(gPIDFile, "w");
if (fp != NULL) {
fprintf(fp, "%ld\n", (long) getpid());
junk = fclose(fp);
assert(junk == 0);
}
}
} else {
if (gMDNSPlatformPosixVerboseLevel > 0) {
fprintf(stderr, "%s: Starting in foreground mode, PID %ld\n", gProgramName, (long) getpid());
}
}
status = mDNS_Init(&mDNSStorage, &PlatformStorage,
mDNS_Init_NoCache, mDNS_Init_ZeroCacheSize,
mDNS_Init_AdvertiseLocalAddresses,
mDNS_Init_NoInitCallback, mDNS_Init_NoInitCallbackContext);
if (status != mStatus_NoError) return(2);
status = RegisterOurServices();
if (status != mStatus_NoError) return(2);
signal(SIGHUP, HandleSigHup); // SIGHUP has to be sent by kill -HUP <pid>
signal(SIGINT, HandleSigInt); // SIGINT is what you get for a Ctrl-C
signal(SIGQUIT, HandleSigQuit); // SIGQUIT is what you get for a Ctrl-\ (indeed)
signal(SIGUSR1, HandleSigUsr1); // SIGUSR1 has to be sent by kill -USR1 <pid>
while (!gStopNow)
{
int nfds = 0;
fd_set readfds;
struct timeval timeout;
int result;
// 1. Set up the fd_set as usual here.
// This example client has no file descriptors of its own,
// but a real application would call FD_SET to add them to the set here
FD_ZERO(&readfds);
// 2. Set up the timeout.
// This example client has no other work it needs to be doing,
// so we set an effectively infinite timeout
timeout.tv_sec = 0x3FFFFFFF;
timeout.tv_usec = 0;
// 3. Give the mDNSPosix layer a chance to add its information to the fd_set and timeout
mDNSPosixGetFDSet(&mDNSStorage, &nfds, &readfds, &timeout);
// 4. Call select as normal
verbosedebugf("select(%d, %d.%06d)", nfds, timeout.tv_sec, timeout.tv_usec);
result = select(nfds, &readfds, NULL, NULL, &timeout);
if (result < 0)
{
verbosedebugf("select() returned %d errno %d", result, errno);
if (errno != EINTR) gStopNow = mDNStrue;
else
{
if (gReceivedSigUsr1)
{
gReceivedSigUsr1 = mDNSfalse;
gMDNSPlatformPosixVerboseLevel += 1;
if (gMDNSPlatformPosixVerboseLevel > 2)
gMDNSPlatformPosixVerboseLevel = 0;
if ( gMDNSPlatformPosixVerboseLevel > 0 )
fprintf(stderr, "\nVerbose level %d\n", gMDNSPlatformPosixVerboseLevel);
}
if (gReceivedSigHup)
{
if (gMDNSPlatformPosixVerboseLevel > 0)
fprintf(stderr, "\nSIGHUP\n");
gReceivedSigHup = mDNSfalse;
DeregisterOurServices();
status = mDNSPlatformPosixRefreshInterfaceList(&mDNSStorage);
if (status != mStatus_NoError) break;
status = RegisterOurServices();
if (status != mStatus_NoError) break;
}
}
}
else
{
// 5. Call mDNSPosixProcessFDSet to let the mDNSPosix layer do its work
mDNSPosixProcessFDSet(&mDNSStorage, &readfds);
// 6. This example client has no other work it needs to be doing,
// but a real client would do its work here
// ... (do work) ...
}
}
debugf("Exiting");
DeregisterOurServices();
mDNS_Close(&mDNSStorage);
if (status == mStatus_NoError) {
result = 0;
} else {
result = 2;
}
if ( (result != 0) || (gMDNSPlatformPosixVerboseLevel > 0) ) {
fprintf(stderr, "%s: Finished with status %ld, result %d\n", gProgramName, status, result);
}
return result;
}
