macaroons: add ip range checker

config_builder.go

@@ -472,7 +472,7 @@ func (d *DefaultWalletImpl) BuildWalletConfig(ctx context.Context,
 		}
 		macaroonService, err = macaroons.NewService(
 			rootKeyStore, "lnd", walletInitParams.StatelessInit,
-			macaroons.IPLockChecker,
+			macaroons.IPLockChecker, macaroons.IPRangeLockChecker,
 			macaroons.CustomChecker(interceptorChain),
 		)
 		if err != nil {

macaroons/constraints.go

@@ -3,6 +3,7 @@ package macaroons
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"strings"
@@ -21,6 +22,10 @@ const (
 	// in the serialized macaroon. We choose a single space as the delimiter
 	// between the because that is also used by the macaroon bakery library.
 	CondLndCustom = "lnd-custom"
+
+	// CondIPRange is the caveat condition name that is used for tying an IP
+	// range to a macaroon.
+	CondIPRange = "iprange"
 )
 
 // CustomCaveatAcceptor is an interface that contains a single method for
@@ -80,9 +85,9 @@ func TimeoutConstraint(seconds int64) func(*macaroon.Macaroon) error {
 	}
 }
 
-// IPLockConstraint locks macaroon to a specific IP address.
+// IPLockConstraint locks a macaroon to a specific IP address. If ipAddr is an
-// If address is an empty string, this constraint does nothing to
+// empty string, this constraint does nothing to accommodate  default value's
-// accommodate default value's desired behavior.
+// desired behavior.
 func IPLockConstraint(ipAddr string) func(*macaroon.Macaroon) error {
 	return func(mac *macaroon.Macaroon) error {
 		if ipAddr != "" {
@@ -93,8 +98,32 @@ func IPLockConstraint(ipAddr string) func(*macaroon.Macaroon) error {
 			}
 			caveat := checkers.Condition("ipaddr",
 				macaroonIPAddr.String())
+
 			return mac.AddFirstPartyCaveat([]byte(caveat))
 		}
+
+		return nil
+	}
+}
+
+// IPRangeLockConstraint locks a macaroon to a specific IP address range. If
+// ipRange is an empty string, this constraint does nothing to accommodate
+// default value's desired behavior.
+func IPRangeLockConstraint(ipRange string) func(*macaroon.Macaroon) error {
+	return func(mac *macaroon.Macaroon) error {
+		if ipRange != "" {
+			_, parsedNet, err := net.ParseCIDR(ipRange)
+			if err != nil {
+				return fmt.Errorf("incorrect macaroon IP "+
+					"range: %w", err)
+			}
+			caveat := checkers.Condition(
+				CondIPRange, parsedNet.String(),
+			)
+
+			return mac.AddFirstPartyCaveat([]byte(caveat))
+		}
+
 		return nil
 	}
 }
@@ -122,6 +151,39 @@ func IPLockChecker() (string, checkers.Func) {
 	}
 }
 
+// IPRangeLockChecker accepts client IP range from the validation context and
+// compares it with the IP range locked in the macaroon. It is of the `Checker`
+// type.
+func IPRangeLockChecker() (string, checkers.Func) {
+	return CondIPRange, func(ctx context.Context, cond, arg string) error {
+		// Get peer info and extract IP range from it for macaroon
+		// check.
+		pr, ok := peer.FromContext(ctx)
+		if !ok {
+			return errors.New("unable to get peer info from " +
+				"context")
+		}
+		peerAddr, _, err := net.SplitHostPort(pr.Addr.String())
+		if err != nil {
+			return fmt.Errorf("unable to parse peer address: %w",
+				err)
+		}
+
+		_, ipNet, err := net.ParseCIDR(arg)
+		if err != nil {
+			return fmt.Errorf("unable to parse macaroon IP "+
+				"range: %w", err)
+		}
+
+		if !ipNet.Contains(net.ParseIP(peerAddr)) {
+			return errors.New("macaroon locked to different " +
+				"IP range")
+		}
+
+		return nil
+	}
+}
+
 // CustomConstraint returns a function that adds a custom caveat condition to
 // a macaroon.
 func CustomConstraint(name, condition string) func(*macaroon.Macaroon) error {