Allow arbitrary addresses to be set in listen_addresses

Only works on OpenBSD/FreeBSD/Linux (including Android)

Fixes #1362

dnscrypt-proxy/proxy.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	crypto_rand "crypto/rand"
 	"encoding/binary"
 	"net"
@@ -288,16 +289,6 @@ func (proxy *Proxy) udpListener(clientPc *net.UDPConn) {
 	}
 }
 
-func (proxy *Proxy) udpListenerFromAddr(listenAddr *net.UDPAddr) error {
-	clientPc, err := net.ListenUDP("udp", listenAddr)
-	if err != nil {
-		return err
-	}
-	proxy.registerUDPListener(clientPc)
-	dlog.Noticef("Now listening to %v [UDP]", listenAddr)
-	return nil
-}
-
 func (proxy *Proxy) tcpListener(acceptPc *net.TCPListener) {
 	defer acceptPc.Close()
 	for {
@@ -326,22 +317,44 @@ func (proxy *Proxy) tcpListener(acceptPc *net.TCPListener) {
 	}
 }
 
-func (proxy *Proxy) tcpListenerFromAddr(listenAddr *net.TCPAddr) error {
+func (proxy *Proxy) udpListenerFromAddr(listenAddr *net.UDPAddr) error {
-	acceptPc, err := net.ListenTCP("tcp", listenAddr)
+	listenConfig, err := proxy.udpListenerConfig()
 	if err != nil {
 		return err
 	}
-	proxy.registerTCPListener(acceptPc)
+	clientPc, err := listenConfig.ListenPacket(context.Background(), "udp", listenAddr.String())
+	if err != nil {
+		return err
+	}
+	proxy.registerUDPListener(clientPc.(*net.UDPConn))
+	dlog.Noticef("Now listening to %v [UDP]", listenAddr)
+	return nil
+}
+
+func (proxy *Proxy) tcpListenerFromAddr(listenAddr *net.TCPAddr) error {
+	listenConfig, err := proxy.tcpListenerConfig()
+	if err != nil {
+		return err
+	}
+	acceptPc, err := listenConfig.Listen(context.Background(), "tcp", listenAddr.String())
+	if err != nil {
+		return err
+	}
+	proxy.registerTCPListener(acceptPc.(*net.TCPListener))
 	dlog.Noticef("Now listening to %v [TCP]", listenAddr)
 	return nil
 }
 
 func (proxy *Proxy) localDoHListenerFromAddr(listenAddr *net.TCPAddr) error {
-	acceptPc, err := net.ListenTCP("tcp", listenAddr)
+	listenConfig, err := proxy.tcpListenerConfig()
 	if err != nil {
 		return err
 	}
-	proxy.registerLocalDoHListener(acceptPc)
+	acceptPc, err := listenConfig.Listen(context.Background(), "tcp", listenAddr.String())
+	if err != nil {
+		return err
+	}
+	proxy.registerLocalDoHListener(acceptPc.(*net.TCPListener))
 	dlog.Noticef("Now listening to https://%v%v [DoH]", listenAddr, proxy.localDoHPath)
 	return nil
 }

dnscrypt-proxy/setsockopts_darwin.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"net"
+	"syscall"
+)
+
+func (proxy *Proxy) udpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_DF, 0)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_RCVBUF, 4096)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_SNDBUF, 4096)
+			})
+			return nil
+		},
+	}, nil
+}
+
+func (proxy *Proxy) tcpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+			})
+			return nil
+		},
+	}, nil
+}

dnscrypt-proxy/setsockopts_freebsd.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"net"
+	"syscall"
+)
+
+func (proxy *Proxy) udpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_BINDANY, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IPV6, syscall.IPV6_BINDANY, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_DF, 0)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_RCVBUF, 4096)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_SNDBUF, 4096)
+			})
+			return nil
+		},
+	}, nil
+}
+
+func (proxy *Proxy) tcpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_BINDANY, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IPV6, syscall.IPV6_BINDANY, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+			})
+			return nil
+		},
+	}, nil
+}

dnscrypt-proxy/setsockopts_linux.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"net"
+	"syscall"
+)
+
+func (proxy *Proxy) udpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_FREEBIND, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_DF, 0)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_MTU_DISCOVER, syscall.IP_PMTUDISC_DONT)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_RCVBUFFORCE, 4096)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_SNDBUFFORCE, 4096)
+			})
+			return nil
+		},
+	}, nil
+}
+
+func (proxy *Proxy) tcpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_FREEBIND, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_QUICKACK, 1)
+			})
+			return nil
+		},
+	}, nil
+}

dnscrypt-proxy/setsockopts_openbsd.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"net"
+	"syscall"
+)
+
+func (proxy *Proxy) udpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_BINDANY, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_DF, 0)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_RCVBUF, 4096)
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_SNDBUF, 4096)
+			})
+			return nil
+		},
+	}, nil
+}
+
+func (proxy *Proxy) tcpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_BINDANY, 1)
+				_ = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+			})
+			return nil
+		},
+	}, nil
+}

dnscrypt-proxy/setsockopts_others.go

@@ -0,0 +1,15 @@
+// +build !freebsd,!openbsd,!windows,!darwin,!linux
+
+package main
+
+import (
+	"net"
+)
+
+func (proxy *Proxy) udpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{}, nil
+}
+
+func (proxy *Proxy) tcpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{}, nil
+}

dnscrypt-proxy/setsockopts_windows.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"net"
+	"syscall"
+)
+
+func (proxy *Proxy) udpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+				_ = syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, syscall.SO_RCVBUF, 4096)
+				_ = syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, syscall.SO_SNDBUF, 4096)
+			})
+			return nil
+		},
+	}, nil
+}
+
+func (proxy *Proxy) tcpListenerConfig() (*net.ListenConfig, error) {
+	return &net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			_ = c.Control(func(fd uintptr) {
+				_ = syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IP, syscall.IP_TOS, 0x70)
+			})
+			return nil
+		},
+	}, nil
+}