lang/funcs: update cidrsubnet and cidrhost for 64-bit systems (#25517)

* upgrade go-cidr to v1.1.0

* lang/funcs: refactor Subnet and Host functions to support 64-bit systems

* add test cases and remove no-longer-needed validation

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/aliyun/alibaba-cloud-sdk-go v0.0.0-20190329064014-6e358769c32a
 	github.com/aliyun/aliyun-oss-go-sdk v0.0.0-20190103054945-8205d1f41e70
 	github.com/aliyun/aliyun-tablestore-go-sdk v4.1.2+incompatible
-	github.com/apparentlymart/go-cidr v1.0.1
+	github.com/apparentlymart/go-cidr v1.1.0
 	github.com/apparentlymart/go-dump v0.0.0-20190214190832-042adf3cf4a0
 	github.com/apparentlymart/go-userdirs v0.0.0-20190512014041-4a23807e62b9
 	github.com/apparentlymart/go-versions v1.0.0

go.sum

@@ -76,6 +76,8 @@ github.com/antchfx/xquery v0.0.0-20180515051857-ad5b8c7a47b0 h1:JaCC8jz0zdMLk2m+
 github.com/antchfx/xquery v0.0.0-20180515051857-ad5b8c7a47b0/go.mod h1:LzD22aAzDP8/dyiCKFp31He4m2GPjl0AFyzDtZzUu9M=
 github.com/apparentlymart/go-cidr v1.0.1 h1:NmIwLZ/KdsjIUlhf+/Np40atNXm/+lZ5txfTJ/SpF+U=
 github.com/apparentlymart/go-cidr v1.0.1/go.mod h1:EBcsNrHc3zQeuaeCeCtQruQm+n9/YjEn/vI25Lg7Gwc=
+github.com/apparentlymart/go-cidr v1.1.0 h1:2mAhrMoF+nhXqxTzSZMUzDHkLjmIHC+Zzn4tdgBZjnU=
+github.com/apparentlymart/go-cidr v1.1.0/go.mod h1:EBcsNrHc3zQeuaeCeCtQruQm+n9/YjEn/vI25Lg7Gwc=
 github.com/apparentlymart/go-dump v0.0.0-20180507223929-23540a00eaa3/go.mod h1:oL81AME2rN47vu18xqj1S1jPIPuN7afo62yKTNn3XMM=
 github.com/apparentlymart/go-dump v0.0.0-20190214190832-042adf3cf4a0 h1:MzVXffFUye+ZcSR6opIgz9Co7WcDx6ZcY+RjfFHoA0I=
 github.com/apparentlymart/go-dump v0.0.0-20190214190832-042adf3cf4a0/go.mod h1:oL81AME2rN47vu18xqj1S1jPIPuN7afo62yKTNn3XMM=

lang/funcs/cidr.go

@@ -2,6 +2,7 @@ package funcs
 
 import (
 	"fmt"
+	"math/big"
 	"net"
 
 	"github.com/apparentlymart/go-cidr/cidr"
@@ -25,7 +26,7 @@ var CidrHostFunc = function.New(&function.Spec{
 	},
 	Type: function.StaticReturnType(cty.String),
 	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
-		var hostNum int
+		var hostNum *big.Int
 		if err := gocty.FromCtyValue(args[1], &hostNum); err != nil {
 			return cty.UnknownVal(cty.String), err
 		}
@@ -34,7 +35,7 @@ var CidrHostFunc = function.New(&function.Spec{
 			return cty.UnknownVal(cty.String), fmt.Errorf("invalid CIDR expression: %s", err)
 		}
 
-		ip, err := cidr.Host(network, hostNum)
+		ip, err := cidr.HostBig(network, hostNum)
 		if err != nil {
 			return cty.UnknownVal(cty.String), err
 		}
@@ -86,7 +87,7 @@ var CidrSubnetFunc = function.New(&function.Spec{
 		if err := gocty.FromCtyValue(args[1], &newbits); err != nil {
 			return cty.UnknownVal(cty.String), err
 		}
-		var netnum int
+		var netnum *big.Int
 		if err := gocty.FromCtyValue(args[2], &netnum); err != nil {
 			return cty.UnknownVal(cty.String), err
 		}
@@ -96,15 +97,7 @@ var CidrSubnetFunc = function.New(&function.Spec{
 			return cty.UnknownVal(cty.String), fmt.Errorf("invalid CIDR expression: %s", err)
 		}
 
-		// For portability with 32-bit systems where the subnet number
+		newNetwork, err := cidr.SubnetBig(network, newbits, netnum)
-		// will be a 32-bit int, we only allow extension of 32 bits in
-		// one call even if we're running on a 64-bit machine.
-		// (Of course, this is significant only for IPv6.)
-		if newbits > 32 {
-			return cty.UnknownVal(cty.String), fmt.Errorf("may not extend prefix by more than 32 bits")
-		}
-
-		newNetwork, err := cidr.Subnet(network, newbits, netnum)
 		if err != nil {
 			return cty.UnknownVal(cty.String), err
 		}

lang/funcs/cidr_test.go

@@ -56,6 +56,12 @@ func TestCidrHost(t *testing.T) {
 			cty.UnknownVal(cty.String),
 			true, // can't have an octet >255
 		},
+		{ // fractions are Not Ok
+			cty.StringVal("10.256.0.0/8"),
+			cty.NumberFloatVal(.75),
+			cty.UnknownVal(cty.String),
+			true,
+		},
 	}
 
 	for _, test := range tests {
@@ -165,6 +171,13 @@ func TestCidrSubnet(t *testing.T) {
 			cty.StringVal("192.168.6.0/24"),
 			false,
 		},
+		{
+			cty.StringVal("fe80::/48"),
+			cty.NumberIntVal(33),
+			cty.NumberIntVal(6),
+			cty.StringVal("fe80::3:0:0:0/81"),
+			false,
+		},
 		{ // not enough bits left
 			cty.StringVal("192.168.0.0/30"),
 			cty.NumberIntVal(4),
@@ -176,21 +189,28 @@ func TestCidrSubnet(t *testing.T) {
 			cty.StringVal("192.168.0.0/168"),
 			cty.NumberIntVal(2),
 			cty.NumberIntVal(16),
-			cty.StringVal("fe80:0:0:6::/64"),
+			cty.UnknownVal(cty.String),
 			true,
 		},
 		{ // not a valid CIDR mask
 			cty.StringVal("not-a-cidr"),
 			cty.NumberIntVal(4),
 			cty.NumberIntVal(6),
-			cty.StringVal("fe80:0:0:6::/64"),
+			cty.UnknownVal(cty.String),
 			true,
 		},
 		{ // can't have an octet >255
 			cty.StringVal("10.256.0.0/8"),
 			cty.NumberIntVal(4),
 			cty.NumberIntVal(6),
-			cty.StringVal("fe80:0:0:6::/64"),
+			cty.UnknownVal(cty.String),
+			true,
+		},
+		{ // fractions are Not Ok
+			cty.StringVal("10.256.0.0/8"),
+			cty.NumberFloatVal(2 / 3),
+			cty.NumberFloatVal(.75),
+			cty.UnknownVal(cty.String),
 			true,
 		},
 	}

vendor/github.com/apparentlymart/go-cidr/cidr/cidr.go

@@ -28,6 +28,16 @@ import (
 // For example, 10.3.0.0/16, extended by 8 bits, with a network number
 // of 5, becomes 10.3.5.0/24 .
 func Subnet(base *net.IPNet, newBits int, num int) (*net.IPNet, error) {
+	return SubnetBig(base, newBits, big.NewInt(int64(num)))
+}
+
+// SubnetBig takes a parent CIDR range and creates a subnet within it with the
+// given number of additional prefix bits and the given network number. It
+// differs from Subnet in that it takes a *big.Int for the num, instead of an int.
+//
+// For example, 10.3.0.0/16, extended by 8 bits, with a network number of 5,
+// becomes 10.3.5.0/24 .
+func SubnetBig(base *net.IPNet, newBits int, num *big.Int) (*net.IPNet, error) {
 	ip := base.IP
 	mask := base.Mask
 
@@ -39,24 +49,32 @@ func Subnet(base *net.IPNet, newBits int, num int) (*net.IPNet, error) {
 	}
 
 	maxNetNum := uint64(1<<uint64(newBits)) - 1
-	if uint64(num) > maxNetNum {
+	if num.Uint64() > maxNetNum {
 		return nil, fmt.Errorf("prefix extension of %d does not accommodate a subnet numbered %d", newBits, num)
 	}
 
 	return &net.IPNet{
-		IP:   insertNumIntoIP(ip, big.NewInt(int64(num)), newPrefixLen),
+		IP:   insertNumIntoIP(ip, num, newPrefixLen),
 		Mask: net.CIDRMask(newPrefixLen, addrLen),
 	}, nil
 }
 
-// Host takes a parent CIDR range and turns it into a host IP address with
+// Host takes a parent CIDR range and turns it into a host IP address with the
-// the given host number.
+// given host number.
 //
 // For example, 10.3.0.0/16 with a host number of 2 gives 10.3.0.2.
 func Host(base *net.IPNet, num int) (net.IP, error) {
+	return HostBig(base, big.NewInt(int64(num)))
+}
+
+// HostBig takes a parent CIDR range and turns it into a host IP address with
+// the given host number. It differs from Host in that it takes a *big.Int for
+// the num, instead of an int.
+//
+// For example, 10.3.0.0/16 with a host number of 2 gives 10.3.0.2.
+func HostBig(base *net.IPNet, num *big.Int) (net.IP, error) {
 	ip := base.IP
 	mask := base.Mask
-	bigNum := big.NewInt(int64(num))
 
 	parentLen, addrLen := mask.Size()
 	hostLen := addrLen - parentLen
@@ -65,11 +83,11 @@ func Host(base *net.IPNet, num int) (net.IP, error) {
 	maxHostNum.Lsh(maxHostNum, uint(hostLen))
 	maxHostNum.Sub(maxHostNum, big.NewInt(1))
 
-	numUint64 := big.NewInt(int64(bigNum.Uint64()))
+	numUint64 := big.NewInt(int64(num.Uint64()))
-	if bigNum.Cmp(big.NewInt(0)) == -1 {
+	if num.Cmp(big.NewInt(0)) == -1 {
-		numUint64.Neg(bigNum)
+		numUint64.Neg(num)
 		numUint64.Sub(numUint64, big.NewInt(int64(1)))
-		bigNum.Sub(maxHostNum, numUint64)
+		num.Sub(maxHostNum, numUint64)
 	}
 
 	if numUint64.Cmp(maxHostNum) == 1 {
@@ -81,7 +99,7 @@ func Host(base *net.IPNet, num int) (net.IP, error) {
 	} else {
 		bitlength = 128
 	}
-	return insertNumIntoIP(ip, bigNum, bitlength), nil
+	return insertNumIntoIP(ip, num, bitlength), nil
 }
 
 // AddressRange returns the first and last addresses in the given CIDR range.

vendor/modules.txt

@@ -87,7 +87,7 @@ github.com/aliyun/aliyun-tablestore-go-sdk/tablestore/search
 github.com/antchfx/xpath
 # github.com/antchfx/xquery v0.0.0-20180515051857-ad5b8c7a47b0
 github.com/antchfx/xquery/xml
-# github.com/apparentlymart/go-cidr v1.0.1
+# github.com/apparentlymart/go-cidr v1.1.0
 ## explicit
 github.com/apparentlymart/go-cidr/cidr
 # github.com/apparentlymart/go-dump v0.0.0-20190214190832-042adf3cf4a0