25-modify-code-to-use-public-api

Modify the code to use a public IP address by default if none is
specified

pkg/lib/ip.go

@@ -1,8 +1,11 @@
 package lib
 
 import (
+	"encoding/json"
+	"io"
 	"log"
 	"net"
+	"net/http"
 )
 
 // GetOutboundIP: gets the oubound IP of this packet
@@ -15,3 +18,44 @@ func GetOutboundIP() net.IP {
 	localAddr := conn.LocalAddr().(*net.UDPAddr)
 	return localAddr.IP
 }
+
+const IP_SERVICE = "https://api.ipify.org?format=json"
+
+type IpResponse struct {
+	Ip string `json:"ip"`
+}
+
+func (i *IpResponse) GetIP() net.IP {
+	return net.ParseIP(i.Ip)
+}
+
+// GetPublicIP: get the nodes public IP address. For when a node is behind NAT
+func GetPublicIP() (net.IP, error) {
+	req, err := http.NewRequest(http.MethodGet, IP_SERVICE, nil)
+
+	if err != nil {
+		return nil, err
+	}
+
+	res, err := http.DefaultClient.Do(req)
+
+	if err != nil {
+		return nil, err
+	}
+
+	resBody, err := io.ReadAll(res.Body)
+
+	if err != nil {
+		return nil, err
+	}
+
+	var jsonResponse IpResponse
+
+	err = json.Unmarshal([]byte(resBody), &jsonResponse)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return jsonResponse.GetIP(), nil
+}