From c6cc38c9cf0c1be72ad608dd662df1799fe63438 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Sat, 31 Jan 2015 01:53:01 +1100
Subject: [PATCH] iplist: Make range descriptions copies of substring, saves
 8MB heap on level1 blocklist!

---
 client.go             |  2 +-
 iplist/iplist.go      | 17 ++++++++---------
 iplist/iplist_test.go |  2 +-
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/client.go b/client.go
index cd65f55d..513e7871 100644
--- a/client.go
+++ b/client.go
@@ -347,7 +347,7 @@ func (cl *Client) setEnvBlocklist() (err error) {
 	var ranges []iplist.Range
 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
-		r, ok, lineErr := iplist.ParseBlocklistP2PLine(scanner.Text())
+		r, ok, lineErr := iplist.ParseBlocklistP2PLine(scanner.Bytes())
 		if lineErr != nil {
 			err = fmt.Errorf("error reading torrent blocklist line: %s", lineErr)
 			return
diff --git a/iplist/iplist.go b/iplist/iplist.go
index 9fe9871e..ed8ac06e 100644
--- a/iplist/iplist.go
+++ b/iplist/iplist.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"net"
 	"sort"
-	"strings"
 )
 
 type IPList struct {
@@ -52,16 +51,16 @@ func (me *IPList) Lookup(ip net.IP) (r *Range) {
 // Parse a line of the PeerGuardian Text Lists (P2P) Format. Returns !ok but
 // no error if a line doesn't contain a range but isn't erroneous, such as
 // comment and blank lines.
-func ParseBlocklistP2PLine(l string) (r Range, ok bool, err error) {
-	l = strings.TrimSpace(l)
-	if len(l) == 0 || strings.HasPrefix(l, "#") {
+func ParseBlocklistP2PLine(l []byte) (r Range, ok bool, err error) {
+	l = bytes.TrimSpace(l)
+	if len(l) == 0 || bytes.HasPrefix(l, []byte("#")) {
 		return
 	}
-	colon := strings.IndexByte(l, ':')
-	hyphen := strings.IndexByte(l[colon+1:], '-') + colon + 1
-	r.Description = l[:colon]
-	r.First = net.ParseIP(l[colon+1 : hyphen])
-	r.Last = net.ParseIP(l[hyphen+1:])
+	colon := bytes.IndexByte(l, ':')
+	hyphen := bytes.IndexByte(l[colon+1:], '-') + colon + 1
+	r.Description = string(l[:colon])
+	r.First = net.ParseIP(string(l[colon+1 : hyphen]))
+	r.Last = net.ParseIP(string(l[hyphen+1:]))
 	if r.First == nil || r.Last == nil {
 		return
 	}
diff --git a/iplist/iplist_test.go b/iplist/iplist_test.go
index cc934c10..08f5b80f 100644
--- a/iplist/iplist_test.go
+++ b/iplist/iplist_test.go
@@ -16,7 +16,7 @@ b:1.2.8.0-1.2.8.255`
 func sampleRanges(tb testing.TB) (ranges []Range, err error) {
 	scanner := bufio.NewScanner(strings.NewReader(sample))
 	for scanner.Scan() {
-		r, ok, _ := ParseBlocklistP2PLine(scanner.Text())
+		r, ok, _ := ParseBlocklistP2PLine(scanner.Bytes())
 		if ok {
 			// tb.Log(r)
 			ranges = append(ranges, r)
-- 
2.44.0