Multicast socket API

net/udp/udp_socket_win.cc

Index: net/udp/udp_socket_win.cc
diff --git a/net/udp/udp_socket_win.cc b/net/udp/udp_socket_win.cc
index 5c6da9fc47c154dfd9e40ad682e980512eb19002..cd3e83c20a22ebf7eb112154e4e4ced8d7b75b79 100644
--- a/net/udp/udp_socket_win.cc
+++ b/net/udp/udp_socket_win.cc
@@ -163,7 +163,10 @@ UDPSocketWin::UDPSocketWin(DatagramSocket::BindType bind_type,
                            net::NetLog* net_log,
                            const net::NetLog::Source& source)
     : socket_(INVALID_SOCKET),
+      sock_addr_family_(0),
       socket_options_(0),
+      multicast_time_to_live_(1),
+      multicast_loopback_mode_(true),
       bind_type_(bind_type),
       rand_int_cb_(rand_int_cb),
       recv_from_address_(NULL),
@@ -355,7 +358,8 @@ int UDPSocketWin::Bind(const IPEndPoint& address) {
 }
 
 int UDPSocketWin::CreateSocket(const IPEndPoint& address) {
-  socket_ = WSASocket(address.GetSockAddrFamily(), SOCK_DGRAM, IPPROTO_UDP,
+  sock_addr_family_ = address.GetSockAddrFamily();
+  socket_ = WSASocket(sock_addr_family_, SOCK_DGRAM, IPPROTO_UDP,
                       NULL, 0, WSA_FLAG_OVERLAPPED);
   if (socket_ == INVALID_SOCKET)
     return MapSystemError(WSAGetLastError());
@@ -584,6 +588,16 @@ int UDPSocketWin::SetSocketOptions() {
     if (rv < 0)
       return MapSystemError(errno);
   }
+  if (multicast_time_to_live_ != 1) {

[wtc, 2013/04/16 19:59:42]

Can you cite a MSDN page or some Microsoft documentation
that says the default value of IP_MULTICAST_TTL is 1 on
Windows?  Or is this default value specified by an RFC?

[Bei Zhang, 2013/04/17 17:53:03]

http://ibiblio.org/pub/linux/docs/HOWTO/other-formats/html_single/Multicast-H...
mentioned the default value is 1. Also the loopback is by default enabled.

On 2013/04/16 19:59:42, wtc wrote:

+    int rv = SetMulticastTimeToLive(multicast_time_to_live_);
+    if (rv != OK)
+      return rv;
+  }
+  if (!multicast_loopback_mode_) {
+    int rv = SetMulticastLoopbackMode(multicast_loopback_mode_);
+    if (rv != OK)
+      return rv;
+  }
   return OK;
 }
 
@@ -614,4 +628,103 @@ bool UDPSocketWin::ReceiveAddressToIPEndpoint(IPEndPoint* address) const {
   return address->FromSockAddr(storage.addr, storage.addr_len);
 }
 
+
+int UDPSocketWin::JoinGroup(
+    const net::IPAddressNumber& group_address) const {
+  DCHECK(CalledOnValidThread());
+  DCHECK(is_connected());
+  int rv = -1;

[wtc, 2013/04/16 19:59:42]

Nit: initialize |rv| to SOCKET_ERROR (which has the value -1).

[Bei Zhang, 2013/04/17 17:53:03]

Done.

+  switch (group_address.size()) {
+    case kIPv4AddressSize: {
+      if (sock_addr_family_ != AF_INET)
+        return ERR_ADDRESS_INVALID;
+      ip_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.imr_multiaddr, &group_address[0], kIPv4AddressSize);
+      rv = setsockopt(socket_, IPPROTO_IP, IP_ADD_MEMBERSHIP,
+                      reinterpret_cast<const char*>(&mreq),
+                      sizeof(mreq));
+      break;
+    }
+    case kIPv6AddressSize: {
+      if (sock_addr_family_ != AF_INET6)
+        return ERR_ADDRESS_INVALID;
+      ipv6_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.ipv6mr_multiaddr, &group_address[0], kIPv6AddressSize);
+      rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
+                      reinterpret_cast<const char*>(&mreq),
+                      sizeof(mreq));
+      break;

[wtc, 2013/04/16 19:59:42]

NOTE: all of my comments on JoinGroup also apply to LeaveGroup.
For brevity I won't repeat them.

Add a default case:
    default:
      NOTREACHED();
      return ERR_ADDRESS_INVALID;

[Bei Zhang, 2013/04/17 17:53:03]

Done.

+    }
+  }
+  return MapSystemError(rv);

[wtc, 2013/04/16 19:59:42]

BUG: this should be:
  if (rv != 0)
    return MapSystemError(WSAGetLastError());
  return OK;

[Bei Zhang, 2013/04/17 17:53:03]

Done.

+}
+
+int UDPSocketWin::LeaveGroup(
+    const net::IPAddressNumber& group_address) const {
+  DCHECK(CalledOnValidThread());
+  DCHECK(is_connected());
+  int rv = -1;
+  switch (group_address.size()) {
+    case kIPv4AddressSize: {
+      if (sock_addr_family_ != AF_INET)
+        return ERR_ADDRESS_INVALID;
+      ip_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.imr_multiaddr, &group_address[0], kIPv4AddressSize);
+      rv = setsockopt(socket_, IPPROTO_IP, IP_DROP_MEMBERSHIP,
+                      reinterpret_cast<const char*>(&mreq),
+                      sizeof(mreq));
+      break;
+    }
+    case kIPv6AddressSize: {
+      if (sock_addr_family_ != AF_INET6)
+        return ERR_ADDRESS_INVALID;
+      ipv6_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.ipv6mr_multiaddr, &group_address[0], kIPv6AddressSize);
+      rv = setsockopt(socket_, IPPROTO_IPV6, IP_DROP_MEMBERSHIP,
+                      reinterpret_cast<const char*>(&mreq),
+                      sizeof(mreq));
+      break;
+    }
+  }
+  return MapSystemError(rv);
+}
+
+int UDPSocketWin::SetMulticastTimeToLive(int time_to_live) {
+  DCHECK(CalledOnValidThread());
+  if (is_connected()) {
+    if (time_to_live < 0 || time_to_live > 255)
+      return ERR_INVALID_ARGUMENT;

[wtc, 2013/04/16 19:59:42]

This check should be moved to line 709, before we save
time_to_live in multicast_time_to_live_.

[Bei Zhang, 2013/04/17 17:53:03]

I'm changing the behavior to make it only works before Bind/Connect to be
consist with other methods. This also applies to SetMulticastLoopbackMode()

On 2013/04/16 19:59:42, wtc wrote:

+    uint8 ttl = time_to_live;
+    int ip_family = sock_addr_family_ == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
+    return MapSystemError(setsockopt(socket_,
+        ip_family,
+        IP_MULTICAST_TTL,
+        reinterpret_cast<const char*>(&ttl),
+        sizeof(ttl)));
+  } else {
+    multicast_time_to_live_ = time_to_live;
+    return OK;
+  }
+}
+
+int UDPSocketWin::SetMulticastLoopbackMode(bool loopback) {
+  DCHECK(CalledOnValidThread());
+  if (is_connected()) {
+    uint8 loop = loopback;

[wtc, 2013/04/16 19:59:42]

NOTE: all of my comments on SetMulticastLoopbackMode also
apply to SetMulticastTimeToLive. For brevity, I won't repeat
them.

BUG?: Are you sure |loop| should be a uint8?  Winsock
usually uses 'int' or 'BOOL' for socket options that are
boolean flags.  These two MSDN pages say |loop| should be a
DWORD:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms738586(v=vs.85).aspx

http://msdn.microsoft.com/en-us/library/windows/desktop/ms738574(v=vs.85).aspx

The second MSDN page says IPV6_MULTICAST_LOOP should be
used with IPPROTO_IPV6.

Also note the "Note" in this MSDN page about the difference
of IP_MULTICAST_LOOP between Windows and Unix:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms739161(v=vs.85).aspx

[Bei Zhang, 2013/04/17 17:53:03]

Thank you for pointing that out. Adding the notes to the  documents about this
issue.

On 2013/04/16 19:59:42, wtc wrote:

[wtc, 2013/04/17 22:06:50]

I think you should also add the notes to the
udp_socket_libevent.h and udp_socket_win.h header files.

+    int ip_family = sock_addr_family_ == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
+    return MapSystemError(setsockopt(socket_,

[wtc, 2013/04/16 19:59:42]

BUG: MapSystemError() takes a socket error code
(WSAGetLastError(), or errno for POSIX). But setsockopt()
returns a success/failure status (0 or -1/SOCKET_ERROR).

[Bei Zhang, 2013/04/17 17:53:03]

Done.

+        ip_family,
+        IP_MULTICAST_LOOP,
+        reinterpret_cast<const char*>(&loop),
+        sizeof(loop)));
+  } else {
+    multicast_loopback_mode_ = loopback;

[wtc, 2013/04/16 19:59:42]

I think this function should always store |loopback| in
multicast_loopback_mode_, like this:

  int UDPSocketWin::SetMulticastLoopbackMode(bool loopback) {
    DCHECK(CalledOnValidThread());
    multicast_loopback_mode_ = loopback;
    if (is_connected()) {
      // call setsockopt
      ...
    }
    return OK;
  }

Are you sure this socket option cannot be set before the
UDP socket is connected?

[Bei Zhang, 2013/04/17 17:53:03]

Done.

+    return OK;
+  }
+}
+
 }  // namespace net