Fix ip-range for classless subnet masks

The `LastIPInSubnet` function worked only for classful subnet
masks (e.g. /8, /16, /24). For non standard subnet masks this
returned the wrong ip address.

This works now for all subnet mask. A unit test is added to
ensure this.

Signed-off-by: Paul Holzinger <paul.holzinger@web.de>
This commit is contained in:
Paul Holzinger
2020-11-23 11:41:40 +01:00
parent 5292d5a7b8
commit 70e7acdb23
2 changed files with 69 additions and 7 deletions

View File

@ -54,14 +54,10 @@ func LastIPInSubnet(addr *net.IPNet) (net.IP, error) { //nolint:interfacer
ones, bits := cidr.Mask.Size()
if ones == bits {
return FirstIPInSubnet(cidr)
return cidr.IP, nil
}
hostStart := ones / 8
// Handle the first host byte
cidr.IP[hostStart] |= 0xff & cidr.Mask[hostStart]
// Fill the rest with ones
for i := hostStart; i < len(cidr.IP); i++ {
cidr.IP[i] = 0xff
for i := range cidr.IP {
cidr.IP[i] = cidr.IP[i] | ^cidr.Mask[i]
}
return cidr.IP, nil
}
@ -73,6 +69,10 @@ func FirstIPInSubnet(addr *net.IPNet) (net.IP, error) { //nolint:interfacer
if err != nil {
return nil, err
}
ones, bits := cidr.Mask.Size()
if ones == bits {
return cidr.IP, nil
}
cidr.IP[len(cidr.IP)-1]++
return cidr.IP, nil
}

View File

@ -33,3 +33,65 @@ func TestNextSubnet(t *testing.T) {
})
}
}
func TestFirstIPInSubnet(t *testing.T) {
tests := []struct {
name string
args *net.IPNet
want net.IP
wantErr bool
}{
{"class b", parseCIDR("192.168.0.0/16"), net.ParseIP("192.168.0.1"), false},
{"class c", parseCIDR("192.168.1.0/24"), net.ParseIP("192.168.1.1"), false},
{"cidr /23", parseCIDR("192.168.0.0/23"), net.ParseIP("192.168.0.1"), false},
{"cidr /25", parseCIDR("192.168.1.0/25"), net.ParseIP("192.168.1.1"), false},
{"cidr /26", parseCIDR("172.16.1.128/26"), net.ParseIP("172.16.1.129"), false},
{"class a", parseCIDR("10.0.0.0/8"), net.ParseIP("10.0.0.1"), false},
{"cidr /32", parseCIDR("192.168.255.4/32"), net.ParseIP("192.168.255.4"), false},
{"cidr /31", parseCIDR("192.168.255.4/31"), net.ParseIP("192.168.255.5"), false},
}
for _, tt := range tests {
test := tt
t.Run(test.name, func(t *testing.T) {
got, err := FirstIPInSubnet(test.args)
if (err != nil) != test.wantErr {
t.Errorf("FirstIPInSubnet() error = %v, wantErr %v", err, test.wantErr)
return
}
if !got.Equal(test.want) {
t.Errorf("FirstIPInSubnet() got = %v, want %v", got, test.want)
}
})
}
}
func TestLastIPInSubnet(t *testing.T) {
tests := []struct {
name string
args *net.IPNet
want net.IP
wantErr bool
}{
{"class b", parseCIDR("192.168.0.0/16"), net.ParseIP("192.168.255.255"), false},
{"class c", parseCIDR("192.168.1.0/24"), net.ParseIP("192.168.1.255"), false},
{"cidr /23", parseCIDR("192.168.0.0/23"), net.ParseIP("192.168.1.255"), false},
{"cidr /25", parseCIDR("192.168.1.0/25"), net.ParseIP("192.168.1.127"), false},
{"cidr /26", parseCIDR("172.16.1.128/26"), net.ParseIP("172.16.1.191"), false},
{"class a", parseCIDR("10.0.0.0/8"), net.ParseIP("10.255.255.255"), false},
{"cidr /32", parseCIDR("192.168.255.4/32"), net.ParseIP("192.168.255.4"), false},
{"cidr /31", parseCIDR("192.168.255.4/31"), net.ParseIP("192.168.255.5"), false},
}
for _, tt := range tests {
test := tt
t.Run(test.name, func(t *testing.T) {
got, err := LastIPInSubnet(test.args)
if (err != nil) != test.wantErr {
t.Errorf("LastIPInSubnet() error = %v, wantErr %v", err, test.wantErr)
return
}
if !got.Equal(test.want) {
t.Errorf("LastIPInSubnet() got = %v, want %v", got, test.want)
}
})
}
}