diff --git a/p2p/netutil/error.go b/p2p/netutil/error.go
new file mode 100644
index 0000000000..cb21b9cd4c
--- /dev/null
+++ b/p2p/netutil/error.go
@@ -0,0 +1,25 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see .
+
+package netutil
+
+// IsTemporaryError checks whether the given error should be considered temporary.
+func IsTemporaryError(err error) bool {
+ tempErr, ok := err.(interface {
+ Temporary() bool
+ })
+ return ok && tempErr.Temporary() || isPacketTooBig(err)
+}
diff --git a/p2p/netutil/error_test.go b/p2p/netutil/error_test.go
new file mode 100644
index 0000000000..645e48f837
--- /dev/null
+++ b/p2p/netutil/error_test.go
@@ -0,0 +1,73 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see .
+
+package netutil
+
+import (
+ "net"
+ "testing"
+ "time"
+)
+
+// This test checks that isPacketTooBig correctly identifies
+// errors that result from receiving a UDP packet larger
+// than the supplied receive buffer.
+func TestIsPacketTooBig(t *testing.T) {
+ listener, err := net.ListenPacket("udp", "127.0.0.1:0")
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer listener.Close()
+ sender, err := net.Dial("udp", listener.LocalAddr().String())
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer sender.Close()
+
+ sendN := 1800
+ recvN := 300
+ for i := 0; i < 20; i++ {
+ go func() {
+ buf := make([]byte, sendN)
+ for i := range buf {
+ buf[i] = byte(i)
+ }
+ sender.Write(buf)
+ }()
+
+ buf := make([]byte, recvN)
+ listener.SetDeadline(time.Now().Add(1 * time.Second))
+ n, _, err := listener.ReadFrom(buf)
+ if err != nil {
+ if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
+ continue
+ }
+ if !isPacketTooBig(err) {
+ t.Fatalf("unexpected read error: %v", err)
+ }
+ continue
+ }
+ if n != recvN {
+ t.Fatalf("short read: %d, want %d", n, recvN)
+ }
+ for i := range buf {
+ if buf[i] != byte(i) {
+ t.Fatalf("error in pattern")
+ break
+ }
+ }
+ }
+}
diff --git a/p2p/netutil/net.go b/p2p/netutil/net.go
new file mode 100644
index 0000000000..3c3715788d
--- /dev/null
+++ b/p2p/netutil/net.go
@@ -0,0 +1,166 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see .
+
+// Package netutil contains extensions to the net package.
+package netutil
+
+import (
+ "errors"
+ "net"
+ "strings"
+)
+
+var lan4, lan6, special4, special6 Netlist
+
+func init() {
+ // Lists from RFC 5735, RFC 5156,
+ // https://www.iana.org/assignments/iana-ipv4-special-registry/
+ lan4.Add("0.0.0.0/8") // "This" network
+ lan4.Add("10.0.0.0/8") // Private Use
+ lan4.Add("172.16.0.0/12") // Private Use
+ lan4.Add("192.168.0.0/16") // Private Use
+ lan6.Add("fe80::/10") // Link-Local
+ lan6.Add("fc00::/7") // Unique-Local
+ special4.Add("192.0.0.0/29") // IPv4 Service Continuity
+ special4.Add("192.0.0.9/32") // PCP Anycast
+ special4.Add("192.0.0.170/32") // NAT64/DNS64 Discovery
+ special4.Add("192.0.0.171/32") // NAT64/DNS64 Discovery
+ special4.Add("192.0.2.0/24") // TEST-NET-1
+ special4.Add("192.31.196.0/24") // AS112
+ special4.Add("192.52.193.0/24") // AMT
+ special4.Add("192.88.99.0/24") // 6to4 Relay Anycast
+ special4.Add("192.175.48.0/24") // AS112
+ special4.Add("198.18.0.0/15") // Device Benchmark Testing
+ special4.Add("198.51.100.0/24") // TEST-NET-2
+ special4.Add("203.0.113.0/24") // TEST-NET-3
+ special4.Add("255.255.255.255/32") // Limited Broadcast
+
+ // http://www.iana.org/assignments/iana-ipv6-special-registry/
+ special6.Add("100::/64")
+ special6.Add("2001::/32")
+ special6.Add("2001:1::1/128")
+ special6.Add("2001:2::/48")
+ special6.Add("2001:3::/32")
+ special6.Add("2001:4:112::/48")
+ special6.Add("2001:5::/32")
+ special6.Add("2001:10::/28")
+ special6.Add("2001:20::/28")
+ special6.Add("2001:db8::/32")
+ special6.Add("2002::/16")
+}
+
+// Netlist is a list of IP networks.
+type Netlist []net.IPNet
+
+// ParseNetlist parses a comma-separated list of CIDR masks.
+// Whitespace and extra commas are ignored.
+func ParseNetlist(s string) (*Netlist, error) {
+ ws := strings.NewReplacer(" ", "", "\n", "", "\t", "")
+ masks := strings.Split(ws.Replace(s), ",")
+ l := make(Netlist, 0)
+ for _, mask := range masks {
+ if mask == "" {
+ continue
+ }
+ _, n, err := net.ParseCIDR(mask)
+ if err != nil {
+ return nil, err
+ }
+ l = append(l, *n)
+ }
+ return &l, nil
+}
+
+// Add parses a CIDR mask and appends it to the list. It panics for invalid masks and is
+// intended to be used for setting up static lists.
+func (l *Netlist) Add(cidr string) {
+ _, n, err := net.ParseCIDR(cidr)
+ if err != nil {
+ panic(err)
+ }
+ *l = append(*l, *n)
+}
+
+// Contains reports whether the given IP is contained in the list.
+func (l *Netlist) Contains(ip net.IP) bool {
+ if l == nil {
+ return false
+ }
+ for _, net := range *l {
+ if net.Contains(ip) {
+ return true
+ }
+ }
+ return false
+}
+
+// IsLAN reports whether an IP is a local network address.
+func IsLAN(ip net.IP) bool {
+ if ip.IsLoopback() {
+ return true
+ }
+ if v4 := ip.To4(); v4 != nil {
+ return lan4.Contains(v4)
+ }
+ return lan6.Contains(ip)
+}
+
+// IsSpecialNetwork reports whether an IP is located in a special-use network range
+// This includes broadcast, multicast and documentation addresses.
+func IsSpecialNetwork(ip net.IP) bool {
+ if ip.IsMulticast() {
+ return true
+ }
+ if v4 := ip.To4(); v4 != nil {
+ return special4.Contains(v4)
+ }
+ return special6.Contains(ip)
+}
+
+var (
+ errInvalid = errors.New("invalid IP")
+ errUnspecified = errors.New("zero address")
+ errSpecial = errors.New("special network")
+ errLoopback = errors.New("loopback address from non-loopback host")
+ errLAN = errors.New("LAN address from WAN host")
+)
+
+// CheckRelayIP reports whether an IP relayed from the given sender IP
+// is a valid connection target.
+//
+// There are four rules:
+// - Special network addresses are never valid.
+// - Loopback addresses are OK if relayed by a loopback host.
+// - LAN addresses are OK if relayed by a LAN host.
+// - All other addresses are always acceptable.
+func CheckRelayIP(sender, addr net.IP) error {
+ if len(addr) != net.IPv4len && len(addr) != net.IPv6len {
+ return errInvalid
+ }
+ if addr.IsUnspecified() {
+ return errUnspecified
+ }
+ if IsSpecialNetwork(addr) {
+ return errSpecial
+ }
+ if addr.IsLoopback() && !sender.IsLoopback() {
+ return errLoopback
+ }
+ if IsLAN(addr) && !IsLAN(sender) {
+ return errLAN
+ }
+ return nil
+}
diff --git a/p2p/netutil/net_test.go b/p2p/netutil/net_test.go
new file mode 100644
index 0000000000..1ee1fcb4d6
--- /dev/null
+++ b/p2p/netutil/net_test.go
@@ -0,0 +1,173 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see .
+
+package netutil
+
+import (
+ "net"
+ "reflect"
+ "testing"
+
+ "github.com/davecgh/go-spew/spew"
+)
+
+func TestParseNetlist(t *testing.T) {
+ var tests = []struct {
+ input string
+ wantErr error
+ wantList *Netlist
+ }{
+ {
+ input: "",
+ wantList: &Netlist{},
+ },
+ {
+ input: "127.0.0.0/8",
+ wantErr: nil,
+ wantList: &Netlist{{IP: net.IP{127, 0, 0, 0}, Mask: net.CIDRMask(8, 32)}},
+ },
+ {
+ input: "127.0.0.0/44",
+ wantErr: &net.ParseError{Type: "CIDR address", Text: "127.0.0.0/44"},
+ },
+ {
+ input: "127.0.0.0/16, 23.23.23.23/24,",
+ wantList: &Netlist{
+ {IP: net.IP{127, 0, 0, 0}, Mask: net.CIDRMask(16, 32)},
+ {IP: net.IP{23, 23, 23, 0}, Mask: net.CIDRMask(24, 32)},
+ },
+ },
+ }
+
+ for _, test := range tests {
+ l, err := ParseNetlist(test.input)
+ if !reflect.DeepEqual(err, test.wantErr) {
+ t.Errorf("%q: got error %q, want %q", test.input, err, test.wantErr)
+ continue
+ }
+ if !reflect.DeepEqual(l, test.wantList) {
+ spew.Dump(l)
+ spew.Dump(test.wantList)
+ t.Errorf("%q: got %v, want %v", test.input, l, test.wantList)
+ }
+ }
+}
+
+func TestNilNetListContains(t *testing.T) {
+ var list *Netlist
+ checkContains(t, list.Contains, nil, []string{"1.2.3.4"})
+}
+
+func TestIsLAN(t *testing.T) {
+ checkContains(t, IsLAN,
+ []string{ // included
+ "0.0.0.0",
+ "0.2.0.8",
+ "127.0.0.1",
+ "10.0.1.1",
+ "10.22.0.3",
+ "172.31.252.251",
+ "192.168.1.4",
+ "fe80::f4a1:8eff:fec5:9d9d",
+ "febf::ab32:2233",
+ "fc00::4",
+ },
+ []string{ // excluded
+ "192.0.2.1",
+ "1.0.0.0",
+ "172.32.0.1",
+ "fec0::2233",
+ },
+ )
+}
+
+func TestIsSpecialNetwork(t *testing.T) {
+ checkContains(t, IsSpecialNetwork,
+ []string{ // included
+ "192.0.2.1",
+ "192.0.2.44",
+ "2001:db8:85a3:8d3:1319:8a2e:370:7348",
+ "255.255.255.255",
+ "224.0.0.22", // IPv4 multicast
+ "ff05::1:3", // IPv6 multicast
+ },
+ []string{ // excluded
+ "192.0.3.1",
+ "1.0.0.0",
+ "172.32.0.1",
+ "fec0::2233",
+ },
+ )
+}
+
+func checkContains(t *testing.T, fn func(net.IP) bool, inc, exc []string) {
+ for _, s := range inc {
+ if !fn(parseIP(s)) {
+ t.Error("returned false for included address", s)
+ }
+ }
+ for _, s := range exc {
+ if fn(parseIP(s)) {
+ t.Error("returned true for excluded address", s)
+ }
+ }
+}
+
+func parseIP(s string) net.IP {
+ ip := net.ParseIP(s)
+ if ip == nil {
+ panic("invalid " + s)
+ }
+ return ip
+}
+
+func TestCheckRelayIP(t *testing.T) {
+ tests := []struct {
+ sender, addr string
+ want error
+ }{
+ {"127.0.0.1", "0.0.0.0", errUnspecified},
+ {"192.168.0.1", "0.0.0.0", errUnspecified},
+ {"23.55.1.242", "0.0.0.0", errUnspecified},
+ {"127.0.0.1", "255.255.255.255", errSpecial},
+ {"192.168.0.1", "255.255.255.255", errSpecial},
+ {"23.55.1.242", "255.255.255.255", errSpecial},
+ {"192.168.0.1", "127.0.2.19", errLoopback},
+ {"23.55.1.242", "192.168.0.1", errLAN},
+
+ {"127.0.0.1", "127.0.2.19", nil},
+ {"127.0.0.1", "192.168.0.1", nil},
+ {"127.0.0.1", "23.55.1.242", nil},
+ {"192.168.0.1", "192.168.0.1", nil},
+ {"192.168.0.1", "23.55.1.242", nil},
+ {"23.55.1.242", "23.55.1.242", nil},
+ }
+
+ for _, test := range tests {
+ err := CheckRelayIP(parseIP(test.sender), parseIP(test.addr))
+ if err != test.want {
+ t.Errorf("%s from %s: got %q, want %q", test.addr, test.sender, err, test.want)
+ }
+ }
+}
+
+func BenchmarkCheckRelayIP(b *testing.B) {
+ sender := parseIP("23.55.1.242")
+ addr := parseIP("23.55.1.2")
+ for i := 0; i < b.N; i++ {
+ CheckRelayIP(sender, addr)
+ }
+}
diff --git a/p2p/netutil/toobig_notwindows.go b/p2p/netutil/toobig_notwindows.go
new file mode 100644
index 0000000000..47b6438572
--- /dev/null
+++ b/p2p/netutil/toobig_notwindows.go
@@ -0,0 +1,26 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see .
+
+//+build !windows
+
+package netutil
+
+// isPacketTooBig reports whether err indicates that a UDP packet didn't
+// fit the receive buffer. There is no such error on
+// non-Windows platforms.
+func isPacketTooBig(err error) bool {
+ return false
+}
diff --git a/p2p/netutil/toobig_windows.go b/p2p/netutil/toobig_windows.go
new file mode 100644
index 0000000000..dfbb6d44f0
--- /dev/null
+++ b/p2p/netutil/toobig_windows.go
@@ -0,0 +1,40 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see .
+
+//+build windows
+
+package netutil
+
+import (
+ "net"
+ "os"
+ "syscall"
+)
+
+const _WSAEMSGSIZE = syscall.Errno(10040)
+
+// isPacketTooBig reports whether err indicates that a UDP packet didn't
+// fit the receive buffer. On Windows, WSARecvFrom returns
+// code WSAEMSGSIZE and no data if this happens.
+func isPacketTooBig(err error) bool {
+ if opErr, ok := err.(*net.OpError); ok {
+ if scErr, ok := opErr.Err.(*os.SyscallError); ok {
+ return scErr.Err == _WSAEMSGSIZE
+ }
+ return opErr.Err == _WSAEMSGSIZE
+ }
+ return false
+}