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netutil: imp code, docs, tests
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@EugeneOne1
EugeneOne1 committed Feb 11, 2022
1 parent 420e442 commit 52db891
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Showing 4 changed files with 108 additions and 87 deletions.
15 changes: 0 additions & 15 deletions netutil/ip_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -244,17 +244,8 @@ var (
ipNetSink *net.IPNet
)

// flushSinks should be used in Cleanup functions to get rid of values of global
// variables.
func flushSinks() {
errSink = nil
ipNetSink = nil
}

func BenchmarkParseSubnet(b *testing.B) {
b.Run("good_cidr", func(b *testing.B) {
b.Cleanup(flushSinks)

b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Expand All @@ -266,8 +257,6 @@ func BenchmarkParseSubnet(b *testing.B) {
})

b.Run("good_ip", func(b *testing.B) {
b.Cleanup(flushSinks)

b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Expand All @@ -279,8 +268,6 @@ func BenchmarkParseSubnet(b *testing.B) {
})

b.Run("bad_cidr", func(b *testing.B) {
b.Cleanup(flushSinks)

b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, errSink = netutil.ParseSubnet("1.2.3.4//567")
Expand All @@ -290,8 +277,6 @@ func BenchmarkParseSubnet(b *testing.B) {
})

b.Run("bad_ip", func(b *testing.B) {
b.Cleanup(flushSinks)

b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, errSink = netutil.ParseSubnet("1.2.3.4.5")
Expand Down
49 changes: 26 additions & 23 deletions netutil/reversed.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -197,42 +197,43 @@ func IPToReversedAddr(ip net.IP) (arpa string, err error) {
}

// ipv4NetFromReversed parses an IPv4 reverse network. It assumes that arpa is
// a valid domain name and not a single address IPv4 network.
// a valid domain name and is not a doman name with a full IPv4 address.
func ipv4NetFromReversed(arpa string) (subnet *net.IPNet, err error) {
var b uint64
var octet64 uint64
var octetIdx int

ip := make(net.IP, net.IPv4len)
l := 0
for arpa != "" {
dotIdx := strings.LastIndexByte(arpa, '.')
for addr := arpa; addr != ""; addr = addr[:octetIdx-1] {
octetIdx = strings.LastIndexByte(addr, '.') + 1

// Don't check for out of range since the domain is validated to have no
// empty labels.
b, err = strconv.ParseUint(arpa[dotIdx+1:], 10, 8)
octet64, err = strconv.ParseUint(addr[octetIdx:], 10, 8)
if err != nil {
return nil, err
} else if b != 0 && arpa[dotIdx+1] == '0' {
} else if octet64 != 0 && addr[octetIdx] == '0' {
// Octets of an ARPA domain name shouldn't contain leading zero
// except an octet itself equals zero.
//
// See RFC 1035 Section 3.5.
return nil, &AddrError{
Err: errors.Error("leading zero is forbidden at this position"),
Kind: AddrKindLabel,
Addr: arpa[dotIdx+1:],
Addr: addr[octetIdx:],
}
}

ip[l] = byte(b)
ip[l] = byte(octet64)
l++

if dotIdx == -1 {
if octetIdx == 0 {
// Prevent slicing with negative indices.
break
}

arpa = arpa[:dotIdx]
}

if b == 0 {
if octet64 == 0 {
return nil, ErrNotAReversedSubnet
}

Expand All @@ -243,22 +244,24 @@ func ipv4NetFromReversed(arpa string) (subnet *net.IPNet, err error) {
}

// ipv6NetFromReversed parses an IPv6 reverse network. It assumes that arpa is
// a valid domain name and not a single address IPv6 network.
// a valid domain name and is not a doman name with a full IPv6 address.
func ipv6NetFromReversed(arpa string) (subnet *net.IPNet, err error) {
nibIdx := len(arpa) - len(arpaV6Suffix) + len(".") - len("0.")
if nibIdx%2 != 0 {
const nibbleLen = len("0.")

nibbleIdx := len(arpa) - len(arpaV6Suffix) + len(".") - nibbleLen
if nibbleIdx%2 != 0 {
return nil, ErrNotAReversedSubnet
}

var b byte
ip := make(net.IP, net.IPv6len)
l := 0
var b byte
for ; nibIdx >= 0; nibIdx -= len("0.") {
if arpa[nibIdx+1] != '.' {
for ; nibbleIdx >= 0; nibbleIdx -= nibbleLen {
if arpa[nibbleIdx+1] != '.' {
return nil, ErrNotAReversedSubnet
}

c := arpa[nibIdx]
c := arpa[nibbleIdx]
b = fromHexByte(c)
if b == 0xff {
return nil, &RuneError{
Expand All @@ -277,7 +280,7 @@ func ipv6NetFromReversed(arpa string) (subnet *net.IPNet, err error) {
l++
}

if ip[l/2] == 0 {
if b == 0 {
return nil, ErrNotAReversedSubnet
}

Expand All @@ -292,7 +295,9 @@ func ipv6NetFromReversed(arpa string) (subnet *net.IPNet, err error) {
func subnetFromReversedV4(arpa string) (subnet *net.IPNet, err error) {
arpa = arpa[:len(arpa)-len(arpaV4Suffix)]

if dots := strings.Count(arpa, "."); dots == 3 {
if dots := strings.Count(arpa, "."); dots > 3 {
return nil, ErrNotAReversedSubnet
} else if dots == 3 {
var ip net.IP
ip, err = ParseIPv4(arpa)
if err != nil {
Expand All @@ -302,8 +307,6 @@ func subnetFromReversedV4(arpa string) (subnet *net.IPNet, err error) {
reverseIP(ip)

return SingleIPSubnet(ip), nil
} else if dots > 3 {
return nil, ErrNotAReversedSubnet
}

return ipv4NetFromReversed(arpa)
Expand Down
38 changes: 38 additions & 0 deletions netutil/reversed_example_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,3 +60,41 @@ func ExampleIPToReversedAddr_ipv6() {
//
// 4.3.2.1.d.c.b.a.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa
}

func ExampleSubnetFromReversedAddr() {
subnet, err := netutil.SubnetFromReversedAddr("10.in-addr.arpa")
if err != nil {
panic(err)
}

fmt.Println(subnet)

// Output:
//
// 10.0.0.0/8
}

func ExampleSubnetFromReversedAddr_ipv6() {
a := `3.2.1.d.c.b.a.ip6.arpa`
subnet, err := netutil.SubnetFromReversedAddr(a)
if err != nil {
panic(err)
}

fmt.Println(subnet)

// Output:
//
// abcd:1230::/28
}

func ExampleSubnetFromReversedAddr_domain() {
a := `in-addr.arpa`
_, err := netutil.SubnetFromReversedAddr(a)

fmt.Println(err)

// Output:
//
// bad arpa domain name "in-addr.arpa": not a reversed ip network
}
93 changes: 44 additions & 49 deletions netutil/reversed_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,14 +14,15 @@ import (
)

const (
ipv4RevGood = `4.3.2.1.in-addr.arpa`
ipv4Suffix = `.in-addr.arpa`
ipv4RevGood = `4.3.2.1` + ipv4Suffix
ipv4RevGoodUp = `4.3.2.1.In-Addr.Arpa`
ipv4NetRevGood = `10.in-addr.arpa`
ipv4NetRevGood = `10` + ipv4Suffix

ipv4RevGoodUnspecified = `0.0.0.0.in-addr.arpa`
ipv4RevGoodUnspecified = `0.0.0.0` + ipv4Suffix

ipv4Missing = `.0.0.127.in-addr.arpa`
ipv4Char = `1.0.z.127.in-addr.arpa`
ipv4Missing = `.0.0.127` + ipv4Suffix
ipv4Char = `1.0.z.127` + ipv4Suffix
)

const (
Expand Down Expand Up @@ -255,6 +256,15 @@ func TestIPToReversedAddr(t *testing.T) {
}
}

// newIPNet returns an IP network to use in test cases. It doesn't validate
// anything.
func newIPNet(ip net.IP, ones int) (n *net.IPNet) {
return &net.IPNet{
IP: ip,
Mask: net.CIDRMask(ones, len(ip)*8),
}
}

func TestSubnetFromReversedAddr(t *testing.T) {
t.Parallel()

Expand All @@ -265,47 +275,32 @@ func TestSubnetFromReversedAddr(t *testing.T) {
in string
name string
}{{
wantErrAs: nil,
want: &net.IPNet{
IP: testIPv4,
Mask: net.CIDRMask(netutil.IPv4BitLen, netutil.IPv4BitLen),
},
want: newIPNet(testIPv4, netutil.IPv4BitLen),
wantErrAs: nil,
wantErrMsg: "",
in: ipv4RevGood,
name: "good_ipv4_single_addr",
}, {
wantErrAs: nil,
want: &net.IPNet{
IP: testIPv4,
Mask: net.CIDRMask(netutil.IPv4BitLen, netutil.IPv4BitLen),
},
want: newIPNet(testIPv4, netutil.IPv4BitLen),
wantErrAs: nil,
wantErrMsg: "",
in: ipv4RevGood + ".",
name: "good_ipv4_single_addr_fqdn",
}, {
wantErrAs: nil,
want: &net.IPNet{
IP: testIPv4,
Mask: net.CIDRMask(netutil.IPv4BitLen, netutil.IPv4BitLen),
},
want: newIPNet(testIPv4, netutil.IPv4BitLen),
wantErrAs: nil,
wantErrMsg: "",
in: ipv4RevGoodUp,
name: "good_ipv4_single_addr_case",
}, {
wantErrAs: nil,
want: &net.IPNet{
IP: testIPv4ZeroTail,
Mask: net.CIDRMask(netutil.IPv4BitLen, netutil.IPv4BitLen),
},
want: newIPNet(testIPv4ZeroTail, netutil.IPv4BitLen),
wantErrAs: nil,
wantErrMsg: "",
in: `0.0.0.` + ipv4NetRevGood,
name: "good_ipv4_single_addr_leading_zero",
}, {
wantErrAs: nil,
want: &net.IPNet{
IP: testIPv4ZeroTail,
Mask: net.CIDRMask(8, netutil.IPv4BitLen),
},
want: newIPNet(testIPv4ZeroTail, 8),
wantErrAs: nil,
wantErrMsg: "",
in: ipv4NetRevGood,
name: "good_ipv4_subnet",
Expand Down Expand Up @@ -352,37 +347,25 @@ func TestSubnetFromReversedAddr(t *testing.T) {
in: `5.` + ipv4RevGood,
name: "bad_ipv4_too_long",
}, {
wantErrAs: nil,
want: &net.IPNet{
IP: testIPv6,
Mask: net.CIDRMask(netutil.IPv6BitLen, netutil.IPv6BitLen),
},
want: newIPNet(testIPv6, netutil.IPv6BitLen),
wantErrAs: nil,
wantErrMsg: "",
in: ipv6RevGood,
name: "good_ipv6_single_addr",
}, {
want: &net.IPNet{
IP: testIPv6,
Mask: net.CIDRMask(netutil.IPv6BitLen, netutil.IPv6BitLen),
},
want: newIPNet(testIPv6, netutil.IPv6BitLen),
wantErrAs: nil,
wantErrMsg: "",
in: ipv6RevGood + ".",
name: "good_ipv6_single_addr_fqdn",
}, {
want: &net.IPNet{
IP: testIPv6,
Mask: net.CIDRMask(netutil.IPv6BitLen, netutil.IPv6BitLen),
},
want: newIPNet(testIPv6, netutil.IPv6BitLen),
wantErrAs: nil,
wantErrMsg: "",
in: ipv6RevGoodUp,
name: "good_ipv6_single_addr_case",
}, {
want: &net.IPNet{
IP: testIPv6ZeroTail,
Mask: net.CIDRMask(4*17, netutil.IPv6BitLen),
},
want: newIPNet(testIPv6ZeroTail, 4*17),
wantErrAs: nil,
wantErrMsg: "",
in: ipv6NetRevGood,
Expand Down Expand Up @@ -471,6 +454,20 @@ func TestSubnetFromReversedAddr(t *testing.T) {
`not a reversed ip network`,
in: testIPv4.String(),
name: "not_a_reversed_subnet",
}, {
want: nil,
wantErrAs: new(errors.Error),
wantErrMsg: `bad arpa domain name "` + ipv4Suffix[1:] + `": ` +
`not a reversed ip network`,
in: ipv4Suffix[1:],
name: "root_arpa_v4",
}, {
want: nil,
wantErrAs: new(errors.Error),
wantErrMsg: `bad arpa domain name "` + ipv6Suffix[1:] + `": ` +
`not a reversed ip network`,
in: ipv6Suffix[1:],
name: "root_arpa_v6",
}}

for _, tc := range testCases {
Expand Down Expand Up @@ -516,8 +513,6 @@ func BenchmarkSubnetFromReversedAddr(b *testing.B) {

for _, bc := range benchCases {
b.Run(bc.name, func(b *testing.B) {
b.Cleanup(flushSinks)

b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
Expand Down

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