From 75b959099f2ef93424f2ef3aa67f996cfba77f35 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 1 Dec 2016 15:41:52 +1100
Subject: [PATCH] iplist: Begin adding support for parsing CIDR lists

---
 iplist/cidr.go      | 41 +++++++++++++++++++++++++++++++++++++++++
 iplist/cidr_test.go | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)
 create mode 100644 iplist/cidr.go
 create mode 100644 iplist/cidr_test.go

diff --git a/iplist/cidr.go b/iplist/cidr.go
new file mode 100644
index 00000000..e1319641
--- /dev/null
+++ b/iplist/cidr.go
@@ -0,0 +1,41 @@
+package iplist
+
+import (
+	"bufio"
+	"io"
+	"net"
+)
+
+func ParseCIDRListReader(r io.Reader) (ret []Range, err error) {
+	s := bufio.NewScanner(r)
+	for s.Scan() {
+		err = func() (err error) {
+			_, in, err := net.ParseCIDR(s.Text())
+			if err != nil {
+				return
+			}
+			ret = append(ret, Range{
+				First: in.IP,
+				Last:  IPNetLast(in),
+			})
+			return
+		}()
+		if err != nil {
+			return
+		}
+	}
+	return
+}
+
+// Returns the last, inclusive IP in a net.IPNet.
+func IPNetLast(in *net.IPNet) (last net.IP) {
+	n := len(in.IP)
+	if n != len(in.Mask) {
+		panic("wat")
+	}
+	last = make(net.IP, n)
+	for i := 0; i < n; i++ {
+		last[i] = in.IP[i] | ^in.Mask[i]
+	}
+	return
+}
diff --git a/iplist/cidr_test.go b/iplist/cidr_test.go
new file mode 100644
index 00000000..ad904f52
--- /dev/null
+++ b/iplist/cidr_test.go
@@ -0,0 +1,41 @@
+package iplist
+
+import (
+	"bytes"
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestIPNetLast(t *testing.T) {
+	_, in, err := net.ParseCIDR("138.255.252.0/22")
+	require.NoError(t, err)
+	assert.EqualValues(t, []byte{138, 255, 252, 0}, in.IP)
+	assert.EqualValues(t, []byte{255, 255, 252, 0}, in.Mask)
+	assert.EqualValues(t, []byte{138, 255, 255, 255}, IPNetLast(in))
+	_, in, err = net.ParseCIDR("2400:cb00::/31")
+	require.NoError(t, err)
+	assert.EqualValues(t, []byte{0x24, 0, 0xcb, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, in.IP)
+	assert.EqualValues(t, []byte{255, 255, 255, 254, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, in.Mask)
+	assert.EqualValues(t, []byte{0x24, 0, 0xcb, 1, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff}, IPNetLast(in))
+}
+
+func TestParseCIDRList(t *testing.T) {
+	r := bytes.NewBufferString(`2400:cb00::/32
+2405:8100::/32
+2405:b500::/32
+2606:4700::/32
+2803:f800::/32
+2c0f:f248::/32
+2a06:98c0::/29
+`)
+	rs, err := ParseCIDRListReader(r)
+	require.NoError(t, err)
+	require.Len(t, rs, 7)
+	assert.EqualValues(t, Range{
+		First: net.IP{0x28, 3, 0xf8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+		Last:  net.IP{0x28, 3, 0xf8, 0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+	}, rs[4])
+}