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New option in server config: DisableMulticastLoopback. #32

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New option in server config: DisableMulticastLoopback. #32

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a12b948
New option in server config: DisableMulticastLoopback.
reddaly Apr 9, 2015
80d6231
Only set multicast loopback property of valid connections in mdns ser…
gonzojive Apr 21, 2015
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33 changes: 31 additions & 2 deletions server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@ import (
"strings"
"sync"

"github.com/hashicorp/go.net/ipv4"
"github.com/hashicorp/go.net/ipv6"
"github.com/miekg/dns"
)

Expand Down Expand Up @@ -37,6 +39,12 @@ type Config struct {
// interface. If not provided, the system default multicase interface
// is used.
Iface *net.Interface

// Whether to set the IP_MULTICAST_LOOP socket option on the multicast sockets
// opened. Setting this to false allows mDNS clients on the same machine to
// discover the service. See
// http://stackoverflow.com/questions/1719156/is-there-a-way-to-test-multicast-ip-on-same-box
DisableMulticastLoopback bool
}

// mDNS server is used to listen for mDNS queries and respond if we
Expand All @@ -55,8 +63,29 @@ type Server struct {
// NewServer is used to create a new mDNS server from a config
func NewServer(config *Config) (*Server, error) {
// Create the listeners
ipv4List, _ := net.ListenMulticastUDP("udp4", config.Iface, ipv4Addr)
ipv6List, _ := net.ListenMulticastUDP("udp6", config.Iface, ipv6Addr)
ipv4List, err := net.ListenMulticastUDP("udp4", config.Iface, ipv4Addr)
if err != nil {
// TODO(reddaly): Handle this error beyond printing a log message.
log.Printf("[ERR] mdns: Failed to listen to IPv4 mdns multicast address: %v", err)
}
ipv6List, err := net.ListenMulticastUDP("udp6", config.Iface, ipv6Addr)
if err != nil {
// TODO(reddaly): Handle this error beyond printing a log message.
log.Printf("[ERR] mdns: Failed to listen to IPv6 mdns multicast address: %v", err)
}

if ipv4List != nil {
p := ipv4.NewPacketConn(ipv4List)
if err := p.SetMulticastLoopback(!config.DisableMulticastLoopback); err != nil {
return nil, fmt.Errorf("could not set multicast loopback attribute of ipv4 connection: %v", err)
}
}
if ipv6List != nil {
p := ipv6.NewPacketConn(ipv6List)
if err := p.SetMulticastLoopback(!config.DisableMulticastLoopback); err != nil {
return nil, fmt.Errorf("could not set multicast loopback attribute of ipv6 connection: %v", err)
}
}

// Check if we have any listener
if ipv4List == nil && ipv6List == nil {
Expand Down