Update public address handling in P2P initialization

Add logic to fetch and set public address if not provided. This includes
making an HTTP request to get the public IP and updating the address
port to match the listen address. This ensures the P2P node can
correctly identify and use its public address when not explicitly set.

p2p/p2p.go

@@ -3,9 +3,12 @@ package p2p
 import (
 	"context"
 	"encoding/hex"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"math/rand"
+	"net/http"
 	"strings"
 	"sync"
 	"time"
@@ -73,6 +76,37 @@ func New(addr, publicAddr, version, peers, privKeyStr string, feederNode bool, b
 		if err != nil {
 			return nil, err
 		}
+	} else {
+		timeout := 5 * time.Second
+		ctx, cancel := context.WithTimeout(context.Background(), timeout)
+		defer cancel()
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, "http://ip-api.com/json/", http.NoBody)
+		if err != nil {
+			return nil, err
+		}
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			return nil, err
+		}
+		defer resp.Body.Close()
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return nil, err
+		}
+		var ip struct {
+			Query string
+		}
+		err = json.Unmarshal(body, &ip)
+		if err != nil {
+			return nil, err
+		}
+		guessedPublicAddr := ip.Query
+		addrPort := addr[strings.LastIndex(addr, "/")+1:]
+		guessedPublicAddr = fmt.Sprintf("/ip4/%s/tcp/%s", guessedPublicAddr, addrPort)
+		publicMultiAddr, err = multiaddr.NewMultiaddr(guessedPublicAddr)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	prvKey, err := privateKey(privKeyStr)
@@ -110,6 +144,16 @@ func New(addr, publicAddr, version, peers, privKeyStr string, feederNode bool, b
 	if err != nil {
 		return nil, err
 	}
+	// Update public address port to match the listen address.
+	if publicAddr == "" {
+		// Update the port of publicMultiAddr to match the port of p2pHost.Addrs()[0]
+		port := p2pHost.Addrs()[0].String()
+		port = port[strings.LastIndex(port, "/")+1:]
+		publicMultiAddr, err = multiaddr.NewMultiaddr(fmt.Sprintf("%s/tcp/%s", publicMultiAddr.String(), port))
+		if err != nil {
+			return nil, err
+		}
+	}
 	// Todo: try to understand what will happen if user passes a multiaddr with p2p public and a private key which doesn't match.
 	// For example, a user passes the following multiaddr: --p2p-addr=/ip4/0.0.0.0/tcp/7778/p2p/(SomePublicKey) and also passes a
 	// --p2p-private-key="SomePrivateKey". However, the private public key pair don't match, in this case what will happen?