p2p/netutil: new package for network utilities

The new package contains three things for now:

- IP network list parsing and matching
- The WSAEMSGSIZE workaround, which is duplicated in p2p/discover and
  p2p/discv5.

6 files changed, 503 insertions, 0 deletions

diff --git a/p2p/netutil/error.go b/p2p/netutil/error.go
new file mode 100644
index 000000000..cb21b9cd4
--- /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 <http://www.gnu.org/licenses/>.
+
+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 000000000..645e48f83
--- /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 <http://www.gnu.org/licenses/>.
+
+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 000000000..3c3715788
--- /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 <http://www.gnu.org/licenses/>.
+
+// 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 000000000..1ee1fcb4d
--- /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 <http://www.gnu.org/licenses/>.
+
+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 000000000..47b643857
--- /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 <http://www.gnu.org/licenses/>.
+
+//+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 000000000..dfbb6d44f
--- /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 <http://www.gnu.org/licenses/>.
+
+//+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
+}