lnd.xprv/lncfg/address.go
Olaoluwa Osuntokun 3ad8b86bac
Merge pull request #5007 from Roasbeef/ipv6-tor-parse-fix
lncfg: add IPv6 resolution bypass & account for local hostname aliases
2021-02-10 23:49:47 -08:00

366 lines
11 KiB
Go

package lncfg
import (
"context"
"crypto/tls"
"encoding/hex"
"fmt"
"net"
"strconv"
"strings"
"github.com/btcsuite/btcd/btcec"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/tor"
)
var (
loopBackAddrs = []string{"localhost", "127.0.0.1", "[::1]"}
)
// TCPResolver is a function signature that resolves an address on a given
// network.
type TCPResolver = func(network, addr string) (*net.TCPAddr, error)
// NormalizeAddresses returns a new slice with all the passed addresses
// normalized with the given default port and all duplicates removed.
func NormalizeAddresses(addrs []string, defaultPort string,
tcpResolver TCPResolver) ([]net.Addr, error) {
result := make([]net.Addr, 0, len(addrs))
seen := map[string]struct{}{}
for _, addr := range addrs {
parsedAddr, err := ParseAddressString(
addr, defaultPort, tcpResolver,
)
if err != nil {
return nil, err
}
if _, ok := seen[parsedAddr.String()]; !ok {
result = append(result, parsedAddr)
seen[parsedAddr.String()] = struct{}{}
}
}
return result, nil
}
// EnforceSafeAuthentication enforces "safe" authentication taking into account
// the interfaces that the RPC servers are listening on, and if macaroons and
// TLS is activated or not. To protect users from using dangerous config
// combinations, we'll prevent disabling authentication if the server is
// listening on a public interface.
func EnforceSafeAuthentication(addrs []net.Addr, macaroonsActive,
tlsActive bool) error {
// We'll now examine all addresses that this RPC server is listening
// on. If it's a localhost address or a private address, we'll skip it,
// otherwise, we'll return an error if macaroons are inactive.
for _, addr := range addrs {
if IsLoopback(addr.String()) || IsUnix(addr) || IsPrivate(addr) {
continue
}
if !macaroonsActive {
return fmt.Errorf("detected RPC server listening on "+
"publicly reachable interface %v with "+
"authentication disabled! Refusing to start "+
"with --no-macaroons specified", addr)
}
if !tlsActive {
return fmt.Errorf("detected RPC server listening on "+
"publicly reachable interface %v with "+
"encryption disabled! Refusing to start "+
"with --no-rest-tls specified", addr)
}
}
return nil
}
// parseNetwork parses the network type of the given address.
func parseNetwork(addr net.Addr) string {
switch addr := addr.(type) {
// TCP addresses resolved through net.ResolveTCPAddr give a default
// network of "tcp", so we'll map back the correct network for the given
// address. This ensures that we can listen on the correct interface
// (IPv4 vs IPv6).
case *net.TCPAddr:
if addr.IP.To4() != nil {
return "tcp4"
}
return "tcp6"
default:
return addr.Network()
}
}
// ListenOnAddress creates a listener that listens on the given address.
func ListenOnAddress(addr net.Addr) (net.Listener, error) {
return net.Listen(parseNetwork(addr), addr.String())
}
// TLSListenOnAddress creates a TLS listener that listens on the given address.
func TLSListenOnAddress(addr net.Addr,
config *tls.Config) (net.Listener, error) {
return tls.Listen(parseNetwork(addr), addr.String(), config)
}
// IsLoopback returns true if an address describes a loopback interface.
func IsLoopback(addr string) bool {
for _, loopback := range loopBackAddrs {
if strings.Contains(addr, loopback) {
return true
}
}
return false
}
// isIPv6Host returns true if the host is IPV6 and false otherwise.
func isIPv6Host(host string) bool {
v6Addr := net.ParseIP(host)
if v6Addr == nil {
return false
}
// The documentation states that if the IP address is an IPv6 address,
// then To4() will return nil.
return v6Addr.To4() == nil
}
// IsUnix returns true if an address describes an Unix socket address.
func IsUnix(addr net.Addr) bool {
return strings.HasPrefix(addr.Network(), "unix")
}
// IsPrivate returns true if the address is private. The definitions are,
// https://en.wikipedia.org/wiki/Link-local_address
// https://en.wikipedia.org/wiki/Multicast_address
// Local IPv4 addresses, https://tools.ietf.org/html/rfc1918
// Local IPv6 addresses, https://tools.ietf.org/html/rfc4193
func IsPrivate(addr net.Addr) bool {
switch addr := addr.(type) {
case *net.TCPAddr:
// Check 169.254.0.0/16 and fe80::/10.
if addr.IP.IsLinkLocalUnicast() {
return true
}
// Check 224.0.0.0/4 and ff00::/8.
if addr.IP.IsLinkLocalMulticast() {
return true
}
// Check 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16.
if ip4 := addr.IP.To4(); ip4 != nil {
return ip4[0] == 10 ||
(ip4[0] == 172 && ip4[1]&0xf0 == 16) ||
(ip4[0] == 192 && ip4[1] == 168)
}
// Check fc00::/7.
return len(addr.IP) == net.IPv6len && addr.IP[0]&0xfe == 0xfc
default:
return false
}
}
// ParseAddressString converts an address in string format to a net.Addr that is
// compatible with lnd. UDP is not supported because lnd needs reliable
// connections. We accept a custom function to resolve any TCP addresses so
// that caller is able control exactly how resolution is performed.
func ParseAddressString(strAddress string, defaultPort string,
tcpResolver TCPResolver) (net.Addr, error) {
var parsedNetwork, parsedAddr string
// Addresses can either be in network://address:port format,
// network:address:port, address:port, or just port. We want to support
// all possible types.
if strings.Contains(strAddress, "://") {
parts := strings.Split(strAddress, "://")
parsedNetwork, parsedAddr = parts[0], parts[1]
} else if strings.Contains(strAddress, ":") {
parts := strings.Split(strAddress, ":")
parsedNetwork = parts[0]
parsedAddr = strings.Join(parts[1:], ":")
}
// Only TCP and Unix socket addresses are valid. We can't use IP or
// UDP only connections for anything we do in lnd.
switch parsedNetwork {
case "unix", "unixpacket":
return net.ResolveUnixAddr(parsedNetwork, parsedAddr)
case "tcp", "tcp4", "tcp6":
return tcpResolver(
parsedNetwork, verifyPort(parsedAddr, defaultPort),
)
case "ip", "ip4", "ip6", "udp", "udp4", "udp6", "unixgram":
return nil, fmt.Errorf("only TCP or unix socket "+
"addresses are supported: %s", parsedAddr)
default:
// We'll now possibly apply the default port, use the local
// host short circuit, or parse out an all interfaces listen.
addrWithPort := verifyPort(strAddress, defaultPort)
rawHost, rawPort, _ := net.SplitHostPort(addrWithPort)
// If we reach this point, then we'll check to see if we have
// an onion addresses, if so, we can directly pass the raw
// address and port to create the proper address.
if tor.IsOnionHost(rawHost) {
portNum, err := strconv.Atoi(rawPort)
if err != nil {
return nil, err
}
return &tor.OnionAddr{
OnionService: rawHost,
Port: portNum,
}, nil
}
// Otherwise, we'll attempt the resolve the host. The Tor
// resolver is unable to resolve local or IPv6 addresses, so
// we'll use the system resolver instead.
if rawHost == "" || IsLoopback(rawHost) ||
isIPv6Host(rawHost) {
return net.ResolveTCPAddr("tcp", addrWithPort)
}
// If we've reached this point, then it's possible that this
// resolve returns an error if it isn't able to resolve the
// host. For eaxmple, local entries in /etc/hosts will fail to
// be resolved by Tor. In order to handle this case, we'll fall
// back to the normal system resolver if we fail with an
// identifiable error.
addr, err := tcpResolver("tcp", addrWithPort)
if err != nil {
torErrStr := "tor host is unreachable"
if strings.Contains(err.Error(), torErrStr) {
return net.ResolveTCPAddr("tcp", addrWithPort)
}
return nil, err
}
return addr, nil
}
}
// ParseLNAddressString converts a string of the form <pubkey>@<addr> into an
// lnwire.NetAddress. The <pubkey> must be presented in hex, and result in a
// 33-byte, compressed public key that lies on the secp256k1 curve. The <addr>
// may be any address supported by ParseAddressString. If no port is specified,
// the defaultPort will be used. Any tcp addresses that need resolving will be
// resolved using the custom TCPResolver.
func ParseLNAddressString(strAddress string, defaultPort string,
tcpResolver TCPResolver) (*lnwire.NetAddress, error) {
// Split the address string around the @ sign.
parts := strings.Split(strAddress, "@")
// The string is malformed if there are not exactly two parts.
if len(parts) != 2 {
return nil, fmt.Errorf("invalid lightning address %s: "+
"must be of the form <pubkey-hex>@<addr>", strAddress)
}
// Now, take the first portion as the hex pubkey, and the latter as the
// address string.
parsedPubKey, parsedAddr := parts[0], parts[1]
// Decode the hex pubkey to get the raw compressed pubkey bytes.
pubKeyBytes, err := hex.DecodeString(parsedPubKey)
if err != nil {
return nil, fmt.Errorf("invalid lightning address pubkey: %v", err)
}
// The compressed pubkey should have a length of exactly 33 bytes.
if len(pubKeyBytes) != 33 {
return nil, fmt.Errorf("invalid lightning address pubkey: "+
"length must be 33 bytes, found %d", len(pubKeyBytes))
}
// Parse the pubkey bytes to verify that it corresponds to valid public
// key on the secp256k1 curve.
pubKey, err := btcec.ParsePubKey(pubKeyBytes, btcec.S256())
if err != nil {
return nil, fmt.Errorf("invalid lightning address pubkey: %v", err)
}
// Finally, parse the address string using our generic address parser.
addr, err := ParseAddressString(parsedAddr, defaultPort, tcpResolver)
if err != nil {
return nil, fmt.Errorf("invalid lightning address address: %v", err)
}
return &lnwire.NetAddress{
IdentityKey: pubKey,
Address: addr,
}, nil
}
// verifyPort makes sure that an address string has both a host and a port. If
// there is no port found, the default port is appended. If the address is just
// a port, then we'll assume that the user is using the short cut to specify a
// localhost:port address.
func verifyPort(address string, defaultPort string) string {
host, port, err := net.SplitHostPort(address)
if err != nil {
// If the address itself is just an integer, then we'll assume
// that we're mapping this directly to a localhost:port pair.
// This ensures we maintain the legacy behavior.
if _, err := strconv.Atoi(address); err == nil {
return net.JoinHostPort("localhost", address)
}
// Otherwise, we'll assume that the address just failed to
// attach its own port, so we'll use the default port. In the
// case of IPv6 addresses, if the host is already surrounded by
// brackets, then we'll avoid using the JoinHostPort function,
// since it will always add a pair of brackets.
if strings.HasPrefix(address, "[") {
return address + ":" + defaultPort
}
return net.JoinHostPort(address, defaultPort)
}
// In the case that both the host and port are empty, we'll use the
// default port.
if host == "" && port == "" {
return ":" + defaultPort
}
return address
}
// ClientAddressDialer creates a gRPC dialer that can also dial unix socket
// addresses instead of just TCP addresses.
func ClientAddressDialer(defaultPort string) func(context.Context,
string) (net.Conn, error) {
return func(ctx context.Context, addr string) (net.Conn, error) {
parsedAddr, err := ParseAddressString(
addr, defaultPort, net.ResolveTCPAddr,
)
if err != nil {
return nil, err
}
d := net.Dialer{}
return d.DialContext(
ctx, parsedAddr.Network(), parsedAddr.String(),
)
}
}