all: imp code, docs

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to
 
 ### Added
 
+- Hostname generating for DHCP clients which don't provide their own ([#2723]).
 - New flag `--no-etc-hosts` to disable client domain name lookups in the
   operating system's /etc/hosts files ([#1947]).
 - The ability to set up custom upstreams to resolve PTR queries for local
@@ -30,7 +31,6 @@ and this project adheres to
 
 ### Changed
 
-- Hostname generating for DHCP clients which don't provide their own ([#2723]).
 - Normalization of hostnames with spaces sent by DHCP clients ([#2945]).
 - The access to the private hosts is now forbidden for users from external
   networks ([#2889]).

internal/aghnet/addr.go

@@ -1,7 +1,6 @@
 package aghnet
 
 import (
-	"encoding/hex"
 	"fmt"
 	"net"
 	"strconv"
@@ -102,31 +101,58 @@ func ValidateDomainName(name string) (err error) {
 	return nil
 }
 
-// GenHostName builds the hostname from ip.  In case of using IPv4 the
+// The maximum lengths of generated hostnames for different IP versions.
+const (
+	ipv4HostnameMaxLen = len("192-168-100-10-")
+	ipv6HostnameMaxLen = len("ff80-f076-0000-0000-0000-0000-0000-0010")
+)
+
+// generateIPv4Hostname generates the hostname for specific IP version.
+func generateIPv4Hostname(ipv4 net.IP) (hostname string) {
+	hnData := make([]byte, 0, ipv4HostnameMaxLen)
+	for i, part := range ipv4 {
+		if i > 0 {
+			hnData = append(hnData, '-')
+		}
+		hnData = strconv.AppendUint(hnData, uint64(part), 10)
+	}
+
+	return string(hnData)
+}
+
+// generateIPv6Hostname generates the hostname for specific IP version.
+func generateIPv6Hostname(ipv6 net.IP) (hostname string) {
+	hnData := make([]byte, 0, ipv6HostnameMaxLen)
+	for i, partsNum := 0, net.IPv6len/2; i < partsNum; i++ {
+		if i > 0 {
+			hnData = append(hnData, '-')
+		}
+		for _, val := range ipv6[i*2 : i*2+2] {
+			if val < 10 {
+				hnData = append(hnData, '0')
+			}
+			hnData = strconv.AppendUint(hnData, uint64(val), 16)
+		}
+	}
+
+	return string(hnData)
+}
+
+// GenerateHostName generates the hostname from ip.  In case of using IPv4 the
 // result should be like:
 //
 //   192-168-10-1
 //
 // In case of using IPv6, the result is like:
 //
-//   ff80-f076-0000-0000-0000-0000-0000-0000-0000-0010
+//   ff80-f076-0000-0000-0000-0000-0000-0010
 //
-func GenHostName(ip net.IP) (hostname string) {
-	var parts []string
+func GenerateHostName(ip net.IP) (hostname string) {
 	if ipv4 := ip.To4(); ipv4 != nil {
-		parts = make([]string, net.IPv4len)
-		for i := range parts {
-			parts[i] = strconv.Itoa(int(ipv4[i]))
-		}
+		return generateIPv4Hostname(ipv4)
 	} else if ipv6 := ip.To16(); ipv6 != nil {
-		partsNum := net.IPv6len / 2
-		parts = make([]string, partsNum)
-		dst := make([]byte, hex.EncodedLen(net.IPv6len))
-		hex.Encode(dst, ipv6)
-		for i := 0; i < partsNum; i++ {
-			parts[i] = string(dst[i*4 : (i+1)*4])
-		}
+		return generateIPv6Hostname(ipv6)
 	}
 
-	return strings.Join(parts, "-")
+	return ""
 }

internal/aghnet/addr_test.go

@@ -166,7 +166,11 @@ func TestGenerateHostName(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			assert.Equal(t, tc.want, GenHostName(tc.ip))
+			if tc.name == "good_ipv6" {
+				t.Log("few")
+			}
+			hostname := GenerateHostName(tc.ip)
+			assert.Equal(t, tc.want, hostname)
 		})
 	}
 }

internal/dhcpd/v4.go

@@ -643,7 +643,7 @@ func (s *v4Server) processRequest(req, resp *dhcpv4.DHCPv4) (lease *Lease, ok bo
 		}
 
 		if hostname == "" {
-			hostname = aghnet.GenHostName(reqIP)
+			hostname = aghnet.GenerateHostName(reqIP)
 		}
 
 		lease.Hostname = hostname