device: receive: do not exit immediately on transient UDP receive errors

Some users report seeing lines like:

> Routine: receive incoming IPv4 - stopped

Popping up unexpectedly. Let's sleep and try again before failing, and
also log the error, and perhaps we'll eventually understand this
situation better in future versions.

Because we have to distinguish between the socket being closed
explicitly and whatever error this is, we bump the module to require Go
1.16.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

4 files changed, 32 insertions, 23 deletions

diff --git a/conn/conn_linux.go b/conn/conn_linux.go
index ef5c0ba..642ad7d 100644
--- a/conn/conn_linux.go
+++ b/conn/conn_linux.go
@@ -204,7 +204,7 @@ func (bind *nativeBind) ReceiveIPv6(buff []byte) (int, Endpoint, error) {
 
 	var end NativeEndpoint
 	if bind.sock6 == -1 {
-		return 0, nil, syscall.EAFNOSUPPORT
+		return 0, nil, net.ErrClosed
 	}
 	n, err := receive6(
 		bind.sock6,
@@ -220,7 +220,7 @@ func (bind *nativeBind) ReceiveIPv4(buff []byte) (int, Endpoint, error) {
 
 	var end NativeEndpoint
 	if bind.sock4 == -1 {
-		return 0, nil, syscall.EAFNOSUPPORT
+		return 0, nil, net.ErrClosed
 	}
 	n, err := receive4(
 		bind.sock4,
@@ -237,12 +237,12 @@ func (bind *nativeBind) Send(buff []byte, end Endpoint) error {
 	nend := end.(*NativeEndpoint)
 	if !nend.isV6 {
 		if bind.sock4 == -1 {
-			return syscall.EAFNOSUPPORT
+			return net.ErrClosed
 		}
 		return send4(bind.sock4, nend, buff)
 	} else {
 		if bind.sock6 == -1 {
-			return syscall.EAFNOSUPPORT
+			return net.ErrClosed
 		}
 		return send6(bind.sock6, nend, buff)
 	}
diff --git a/device/receive.go b/device/receive.go
index 0bd22bf..fa31a1a 100644
--- a/device/receive.go
+++ b/device/receive.go
@@ -8,6 +8,7 @@ package device
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"net"
 	"strconv"
 	"sync"
@@ -17,6 +18,7 @@ import (
 	"golang.org/x/crypto/chacha20poly1305"
 	"golang.org/x/net/ipv4"
 	"golang.org/x/net/ipv6"
+
 	"golang.zx2c4.com/wireguard/conn"
 )
 
@@ -117,15 +119,13 @@ func (device *Device) RoutineReceiveIncoming(IP int, bind conn.Bind) {
 	buffer := device.GetMessageBuffer()
 
 	var (
-		err      error
-		size     int
-		endpoint conn.Endpoint
+		err         error
+		size        int
+		endpoint    conn.Endpoint
+		deathSpiral int
 	)
 
 	for {
-
-		// read next datagram
-
 		switch IP {
 		case ipv4.Version:
 			size, endpoint, err = bind.ReceiveIPv4(buffer[:])
@@ -137,8 +137,18 @@ func (device *Device) RoutineReceiveIncoming(IP int, bind conn.Bind) {
 
 		if err != nil {
 			device.PutMessageBuffer(buffer)
+			if errors.Is(err, net.ErrClosed) {
+				return
+			}
+			device.log.Error.Printf("Failed to receive packet: %v", err)
+			if deathSpiral < 10 {
+				deathSpiral++
+				time.Sleep(time.Second / 3)
+				continue
+			}
 			return
 		}
+		deathSpiral = 0
 
 		if size < MinMessageSize {
 			continue
diff --git a/go.mod b/go.mod
index 1dbdb67..11b6c7f 100644
--- a/go.mod
+++ b/go.mod
@@ -1,9 +1,9 @@
 module golang.zx2c4.com/wireguard
 
-go 1.14
+go 1.16
 
 require (
-	golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392
-	golang.org/x/net v0.0.0-20201110031124-69a78807bb2b
-	golang.org/x/sys v0.0.0-20201126233918-771906719818
+	golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad
+	golang.org/x/net v0.0.0-20201224014010-6772e930b67b
+	golang.org/x/sys v0.0.0-20210105210732-16f7687f5001
 )
diff --git a/go.sum b/go.sum
index 96e4ae0..a58d796 100644
--- a/go.sum
+++ b/go.sum
@@ -1,17 +1,16 @@
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392 h1:xYJJ3S178yv++9zXV/hnr29plCAGO9vAFG9dorqaFQc=
-golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
+golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad h1:DN0cp81fZ3njFcrLCytUHRSUkqBjfTo4Tx9RJTWs0EY=
+golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20201110031124-69a78807bb2b h1:uwuIcX0g4Yl1NC5XAz37xsr2lTtcqevgzYNVt49waME=
-golang.org/x/net v0.0.0-20201110031124-69a78807bb2b/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
+golang.org/x/net v0.0.0-20201224014010-6772e930b67b h1:iFwSg7t5GZmB/Q5TjiEAsdoLDrdJRC1RiF2WhuV29Qw=
+golang.org/x/net v0.0.0-20201224014010-6772e930b67b/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
-golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20201126233918-771906719818 h1:f1CIuDlJhwANEC2MM87MBEVMr3jl5bifgsfj90XAF9c=
-golang.org/x/sys v0.0.0-20201126233918-771906719818/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210105210732-16f7687f5001 h1:/dSxr6gT0FNI1MO5WLJo8mTmItROeOKTkDn+7OwWBos=
+golang.org/x/sys v0.0.0-20210105210732-16f7687f5001/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=