From f09c0cd2ec75eb4f51944ab1f7d8aca9a0cca50d Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 17 Dec 2015 23:22:39 +1100
Subject: [PATCH] dht: Move security functions into new file

---
 dht/dht.go      | 58 ---------------------------------------------
 dht/security.go | 63 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 58 deletions(-)
 create mode 100644 dht/security.go

diff --git a/dht/dht.go b/dht/dht.go
index 4fef734d..6df2c225 100644
--- a/dht/dht.go
+++ b/dht/dht.go
@@ -3,8 +3,6 @@ package dht
 import (
 	_ "crypto/sha1"
 	"errors"
-	"fmt"
-	"hash/crc32"
 	"math/big"
 	"math/rand"
 	"net"
@@ -193,62 +191,6 @@ func jitterDuration(average time.Duration, plusMinus time.Duration) time.Duratio
 	return average - plusMinus/2 + time.Duration(rand.Int63n(int64(plusMinus)))
 }
 
-func maskForIP(ip net.IP) []byte {
-	switch {
-	case ip.To4() != nil:
-		return []byte{0x03, 0x0f, 0x3f, 0xff}
-	default:
-		return []byte{0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}
-	}
-}
-
-// Generate the CRC used to make or validate secure node ID.
-func crcIP(ip net.IP, rand uint8) uint32 {
-	if ip4 := ip.To4(); ip4 != nil {
-		ip = ip4
-	}
-	// Copy IP so we can make changes. Go sux at this.
-	ip = append(make(net.IP, 0, len(ip)), ip...)
-	mask := maskForIP(ip)
-	for i := range mask {
-		ip[i] &= mask[i]
-	}
-	r := rand & 7
-	ip[0] |= r << 5
-	return crc32.Checksum(ip[:len(mask)], crc32.MakeTable(crc32.Castagnoli))
-}
-
-// Makes a node ID secure, in-place. The ID is 20 raw bytes.
-// http://www.libtorrent.org/dht_sec.html
-func SecureNodeId(id []byte, ip net.IP) {
-	crc := crcIP(ip, id[19])
-	id[0] = byte(crc >> 24 & 0xff)
-	id[1] = byte(crc >> 16 & 0xff)
-	id[2] = byte(crc>>8&0xf8) | id[2]&7
-}
-
-// Returns whether the node ID is considered secure. The id is the 20 raw
-// bytes. http://www.libtorrent.org/dht_sec.html
-func NodeIdSecure(id string, ip net.IP) bool {
-	if len(id) != 20 {
-		panic(fmt.Sprintf("%q", id))
-	}
-	if ip4 := ip.To4(); ip4 != nil {
-		ip = ip4
-	}
-	crc := crcIP(ip, id[19])
-	if id[0] != byte(crc>>24&0xff) {
-		return false
-	}
-	if id[1] != byte(crc>>16&0xff) {
-		return false
-	}
-	if id[2]&0xf8 != byte(crc>>8&0xf8) {
-		return false
-	}
-	return true
-}
-
 type Peer struct {
 	IP   net.IP
 	Port int
diff --git a/dht/security.go b/dht/security.go
new file mode 100644
index 00000000..e91d1607
--- /dev/null
+++ b/dht/security.go
@@ -0,0 +1,63 @@
+package dht
+
+import (
+	"fmt"
+	"hash/crc32"
+	"net"
+)
+
+func maskForIP(ip net.IP) []byte {
+	switch {
+	case ip.To4() != nil:
+		return []byte{0x03, 0x0f, 0x3f, 0xff}
+	default:
+		return []byte{0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff}
+	}
+}
+
+// Generate the CRC used to make or validate secure node ID.
+func crcIP(ip net.IP, rand uint8) uint32 {
+	if ip4 := ip.To4(); ip4 != nil {
+		ip = ip4
+	}
+	// Copy IP so we can make changes. Go sux at this.
+	ip = append(make(net.IP, 0, len(ip)), ip...)
+	mask := maskForIP(ip)
+	for i := range mask {
+		ip[i] &= mask[i]
+	}
+	r := rand & 7
+	ip[0] |= r << 5
+	return crc32.Checksum(ip[:len(mask)], crc32.MakeTable(crc32.Castagnoli))
+}
+
+// Makes a node ID secure, in-place. The ID is 20 raw bytes.
+// http://www.libtorrent.org/dht_sec.html
+func SecureNodeId(id []byte, ip net.IP) {
+	crc := crcIP(ip, id[19])
+	id[0] = byte(crc >> 24 & 0xff)
+	id[1] = byte(crc >> 16 & 0xff)
+	id[2] = byte(crc>>8&0xf8) | id[2]&7
+}
+
+// Returns whether the node ID is considered secure. The id is the 20 raw
+// bytes. http://www.libtorrent.org/dht_sec.html
+func NodeIdSecure(id string, ip net.IP) bool {
+	if len(id) != 20 {
+		panic(fmt.Sprintf("%q", id))
+	}
+	if ip4 := ip.To4(); ip4 != nil {
+		ip = ip4
+	}
+	crc := crcIP(ip, id[19])
+	if id[0] != byte(crc>>24&0xff) {
+		return false
+	}
+	if id[1] != byte(crc>>16&0xff) {
+		return false
+	}
+	if id[2]&0xf8 != byte(crc>>8&0xf8) {
+		return false
+	}
+	return true
+}
-- 
2.48.1