implement ident.me WAN option provider

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"encoding/xml"
 	"flag"
 	"fmt"
@@ -9,6 +10,7 @@ import (
 	"lux/node"
 	"lux/proto"
 	"lux/rpc"
+	"net"
 	"net/netip"
 	"os"
 	"os/signal"
@@ -383,6 +385,92 @@ func (wan *HostStaticWAN) Provide() (host.LuxOption, error) {
 	return &host.LuxOptionWAN{Addr4: wan.addr4, Addr6: wan.addr6}, nil
 }
 
+type HostIdentWAN struct{}
+
+func dialIdentMe(identIp netip.Addr) (netip.Addr, error) {
+	var network string
+	if identIp.Is6() {
+		network = "tcp6"
+	} else {
+		network = "tcp4"
+	}
+
+	cl, err := net.DialTCP(network, nil,
+		net.TCPAddrFromAddrPort(netip.AddrPortFrom(identIp, 80)))
+	if err != nil {
+		return netip.Addr{}, err
+	}
+	defer cl.Close()
+
+	// I dont want to bundle http package for embedded reasons,
+	// so I will just bang http headers directly
+	const req = "GET / HTTP/1.1\r\nHost: ident.me\r\nUser-Agent: LUX-v1\r\nAccept: */*\r\n\r\n"
+	_, err = cl.Write([]byte(req))
+	if err != nil {
+		return netip.Addr{}, err
+	}
+
+	res := make([]byte, 1024)
+	n, err := cl.Read(res)
+	if err != nil {
+		return netip.Addr{}, err
+	}
+
+	// parse http headers to get response
+	sep := []byte{0x0D, 0x0A, 0x0D, 0x0A}
+
+	ipStr := ""
+	for i := 0; i < n-4; i++ {
+		if bytes.Equal(res[i:i+4], sep) {
+			ipStr = string(res[i+4 : n])
+		}
+	}
+
+	// parse ip
+	if ipStr == "" {
+		return netip.Addr{}, fmt.Errorf("IP not found in ident.me response: %s", string(res))
+	}
+
+	// to prevent panics
+	parsedIp := net.ParseIP(ipStr)
+	if parsedIp == nil {
+		return netip.Addr{}, fmt.Errorf("failed to parse ident.me IP")
+	}
+
+	return proto.LuxProtoIPToAddr(parsedIp), nil
+}
+
+func (*HostIdentWAN) Provide() (host.LuxOption, error) {
+	wan := host.NewLuxOptionWAN()
+	// so first we gonna resolve ident.me and see if there is IPv6
+	addrs, err := net.LookupHost("ident.me")
+	if err != nil {
+		return &wan, err
+	}
+
+	for _, addr := range addrs {
+		ip := net.ParseIP(addr)
+		if ip.To4() == nil && wan.Addr6.IsUnspecified() {
+			// we gonna resolve IPv6
+			addr, err := dialIdentMe(proto.LuxProtoIPToAddr(ip))
+			if err == nil {
+				// we got IPv6
+				wan.Addr6 = addr
+			}
+		} else if wan.Addr4.IsUnspecified() {
+			addr, err := dialIdentMe(proto.LuxProtoIPToAddr(ip))
+			if err != nil {
+				// if no IPv4 its considered catastrophic error
+				return &wan, err
+			} else {
+				wan.Addr4 = addr
+			}
+		}
+	}
+
+	return &wan, nil
+}
+
 func hostMain() {
 	xmlBytes, err := os.ReadFile(configPath)
 	if err != nil {
@@ -444,6 +532,8 @@ func hostMain() {
 				}
 
 				host.AddOptionProvider(&provider)
+			} else if wan.Method == "identme" {
+				host.AddOptionProvider(&HostIdentWAN{})
 			}
 		}
 	}