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Fix windows libp2p #29

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merged 2 commits into from
Aug 7, 2022
Merged

Fix windows libp2p #29

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7ada6b0
Fix client multicast sending on Windows
davidflowerday Jul 27, 2022
3208875
Put in a platform dependent fix for windows to WriteTo on client.go a…
Jul 27, 2022
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26 changes: 24 additions & 2 deletions client.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,10 @@ package zeroconf
import (
"context"
"fmt"
"log"
"math/rand"
"net"
"runtime"
"strings"
"time"

Expand Down Expand Up @@ -436,16 +438,36 @@ func (c *client) sendQuery(msg *dns.Msg) error {
return err
}
if c.ipv4conn != nil {
// See https://pkg.go.dev/golang.org/x/net/ipv4#pkg-note-BUG
// As of Golang 1.18.4
// On Windows, the ControlMessage for ReadFrom and WriteTo methods of PacketConn is not implemented.
var wcm ipv4.ControlMessage
for ifi := range c.ifaces {
wcm.IfIndex = c.ifaces[ifi].Index
switch runtime.GOOS {
case "darwin", "ios", "linux":
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Why is this special-casing darwin, ios and linux, and not windows?

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As I was looking at all the examples of using SetMulticastInterface I saw this example on Google's own Golang docs
https://pkg.go.dev/golang.org/x/net/ipv4#example-RawConn-AdvertisingOSPFHello

I believe it comes down to ControlMessage only being implemented on linux/iOS/darwin mac based platforms and none others. It didn't make sense to specifically call out windows. See https://pkg.go.dev/golang.org/x/net/ipv4#PacketConn.WriteTo

wcm.IfIndex = c.ifaces[ifi].Index
default:
if err := c.ipv4conn.SetMulticastInterface(&c.ifaces[ifi]); err != nil {
log.Printf("[WARN] mdns: Failed to set multicast interface: %v", err)
}
}
c.ipv4conn.WriteTo(buf, &wcm, ipv4Addr)
}
}
if c.ipv6conn != nil {
// See https://pkg.go.dev/golang.org/x/net/ipv6#pkg-note-BUG
// As of Golang 1.18.4
// On Windows, the ControlMessage for ReadFrom and WriteTo methods of PacketConn is not implemented.
var wcm ipv6.ControlMessage
for ifi := range c.ifaces {
wcm.IfIndex = c.ifaces[ifi].Index
switch runtime.GOOS {
case "darwin", "ios", "linux":
wcm.IfIndex = c.ifaces[ifi].Index
default:
if err := c.ipv6conn.SetMulticastInterface(&c.ifaces[ifi]); err != nil {
log.Printf("[WARN] mdns: Failed to set multicast interface: %v", err)
}
}
c.ipv6conn.WriteTo(buf, &wcm, ipv6Addr)
}
}
Expand Down
45 changes: 41 additions & 4 deletions server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ import (
"math/rand"
"net"
"os"
"runtime"
"strings"
"sync"
"time"
Expand Down Expand Up @@ -764,26 +765,62 @@ func (s *Server) multicastResponse(msg *dns.Msg, ifIndex int) error {
return fmt.Errorf("failed to pack msg %v: %w", msg, err)
}
if s.ipv4conn != nil {
// See https://pkg.go.dev/golang.org/x/net/ipv4#pkg-note-BUG
// As of Golang 1.18.4
// On Windows, the ControlMessage for ReadFrom and WriteTo methods of PacketConn is not implemented.
var wcm ipv4.ControlMessage
if ifIndex != 0 {
wcm.IfIndex = ifIndex
switch runtime.GOOS {
case "darwin", "ios", "linux":
wcm.IfIndex = ifIndex
default:
iface, _ := net.InterfaceByIndex(ifIndex)
if err := s.ipv4conn.SetMulticastInterface(iface); err != nil {
log.Printf("[WARN] mdns: Failed to set multicast interface: %v", err)
}
}
s.ipv4conn.WriteTo(buf, &wcm, ipv4Addr)
} else {
for _, intf := range s.ifaces {
wcm.IfIndex = intf.Index
switch runtime.GOOS {
case "darwin", "ios", "linux":
wcm.IfIndex = intf.Index
default:
if err := s.ipv4conn.SetMulticastInterface(&intf); err != nil {
log.Printf("[WARN] mdns: Failed to set multicast interface: %v", err)
}
}
s.ipv4conn.WriteTo(buf, &wcm, ipv4Addr)
}
}
}

if s.ipv6conn != nil {
// See https://pkg.go.dev/golang.org/x/net/ipv6#pkg-note-BUG
// As of Golang 1.18.4
// On Windows, the ControlMessage for ReadFrom and WriteTo methods of PacketConn is not implemented.
var wcm ipv6.ControlMessage
if ifIndex != 0 {
wcm.IfIndex = ifIndex
switch runtime.GOOS {
case "darwin", "ios", "linux":
wcm.IfIndex = ifIndex
default:
iface, _ := net.InterfaceByIndex(ifIndex)
if err := s.ipv6conn.SetMulticastInterface(iface); err != nil {
log.Printf("[WARN] mdns: Failed to set multicast interface: %v", err)
}
}
s.ipv6conn.WriteTo(buf, &wcm, ipv6Addr)
} else {
for _, intf := range s.ifaces {
wcm.IfIndex = intf.Index
switch runtime.GOOS {
case "darwin", "ios", "linux":
wcm.IfIndex = intf.Index
default:
if err := s.ipv6conn.SetMulticastInterface(&intf); err != nil {
log.Printf("[WARN] mdns: Failed to set multicast interface: %v", err)
}
}
s.ipv6conn.WriteTo(buf, &wcm, ipv6Addr)
}
}
Expand Down