net: ListenMulticastUDP to listen concurrently across multiple listeners
This CL introduces new function ListenMulticastUDP to fix
multicast UDP listening across multiple listeners issue,
to replace old multicast methods JoinGroup and LeaveGroup
on UDPConn.
This CL also enables multicast testing by default.
Fixes #2730.
R=rsc, paul.a.lalonde, fullung, devon.odell
CC=golang-dev
https://golang.org/cl/5562048
diff --git a/src/pkg/net/udpsock_posix.go b/src/pkg/net/udpsock_posix.go
index 0f63e95..6108373 100644
--- a/src/pkg/net/udpsock_posix.go
+++ b/src/pkg/net/udpsock_posix.go
@@ -61,7 +61,7 @@
// Implementation of the Conn interface - see Conn for documentation.
// Read implements the Conn Read method.
-func (c *UDPConn) Read(b []byte) (n int, err error) {
+func (c *UDPConn) Read(b []byte) (int, error) {
if !c.ok() {
return 0, os.EINVAL
}
@@ -69,7 +69,7 @@
}
// Write implements the Conn Write method.
-func (c *UDPConn) Write(b []byte) (n int, err error) {
+func (c *UDPConn) Write(b []byte) (int, error) {
if !c.ok() {
return 0, os.EINVAL
}
@@ -167,7 +167,7 @@
}
// ReadFrom implements the PacketConn ReadFrom method.
-func (c *UDPConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
+func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
if !c.ok() {
return 0, nil, os.EINVAL
}
@@ -207,6 +207,11 @@
return c.WriteToUDP(b, a)
}
+// File returns a copy of the underlying os.File, set to blocking mode.
+// It is the caller's responsibility to close f when finished.
+// Closing c does not affect f, and closing f does not affect c.
+func (c *UDPConn) File() (f *os.File, err error) { return c.fd.dup() }
+
// DialUDP connects to the remote address raddr on the network net,
// which must be "udp", "udp4", or "udp6". If laddr is not nil, it is used
// as the local address for the connection.
@@ -246,36 +251,75 @@
return newUDPConn(fd), nil
}
-// File returns a copy of the underlying os.File, set to blocking mode.
-// It is the caller's responsibility to close f when finished.
-// Closing c does not affect f, and closing f does not affect c.
-func (c *UDPConn) File() (f *os.File, err error) { return c.fd.dup() }
-
-// JoinGroup joins the IP multicast group named by addr on ifi,
-// which specifies the interface to join. JoinGroup uses the
-// default multicast interface if ifi is nil.
-func (c *UDPConn) JoinGroup(ifi *Interface, addr IP) error {
- if !c.ok() {
- return os.EINVAL
+// ListenMulticastUDP listens for incoming multicast UDP packets
+// addressed to the group address gaddr on ifi, which specifies
+// the interface to join. ListenMulticastUDP uses default
+// multicast interface if ifi is nil.
+func ListenMulticastUDP(net string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
+ switch net {
+ case "udp", "udp4", "udp6":
+ default:
+ return nil, UnknownNetworkError(net)
}
- setDefaultMulticastSockopts(c.fd)
- ip := addr.To4()
- if ip != nil {
- return joinIPv4GroupUDP(c, ifi, ip)
+ if gaddr == nil || gaddr.IP == nil {
+ return nil, &OpError{"listenmulticastudp", "udp", nil, errMissingAddress}
}
- return joinIPv6GroupUDP(c, ifi, addr)
+ fd, err := internetSocket(net, gaddr.toAddr(), nil, syscall.SOCK_DGRAM, 0, "listen", sockaddrToUDP)
+ if err != nil {
+ return nil, err
+ }
+ c := newUDPConn(fd)
+ ip4 := gaddr.IP.To4()
+ if ip4 != nil {
+ err := listenIPv4MulticastUDP(c, ifi, ip4)
+ if err != nil {
+ c.Close()
+ return nil, err
+ }
+ } else {
+ err := listenIPv6MulticastUDP(c, ifi, gaddr.IP)
+ if err != nil {
+ c.Close()
+ return nil, err
+ }
+ }
+ return c, nil
}
-// LeaveGroup exits the IP multicast group named by addr on ifi.
-func (c *UDPConn) LeaveGroup(ifi *Interface, addr IP) error {
- if !c.ok() {
- return os.EINVAL
+func listenIPv4MulticastUDP(c *UDPConn, ifi *Interface, ip IP) error {
+ if ifi != nil {
+ err := setIPv4MulticastInterface(c.fd, ifi)
+ if err != nil {
+ return err
+ }
}
- ip := addr.To4()
- if ip != nil {
- return leaveIPv4GroupUDP(c, ifi, ip)
+ err := setIPv4MulticastLoopback(c.fd, false)
+ if err != nil {
+ return err
}
- return leaveIPv6GroupUDP(c, ifi, addr)
+ err = joinIPv4GroupUDP(c, ifi, ip)
+ if err != nil {
+ return err
+ }
+ return nil
+}
+
+func listenIPv6MulticastUDP(c *UDPConn, ifi *Interface, ip IP) error {
+ if ifi != nil {
+ err := setIPv6MulticastInterface(c.fd, ifi)
+ if err != nil {
+ return err
+ }
+ }
+ err := setIPv6MulticastLoopback(c.fd, false)
+ if err != nil {
+ return err
+ }
+ err = joinIPv6GroupUDP(c, ifi, ip)
+ if err != nil {
+ return err
+ }
+ return nil
}
func joinIPv4GroupUDP(c *UDPConn, ifi *Interface, ip IP) error {
