add port flag to serve

cmd/ipfs/serve.go

 package main
 
 import (
+	"errors"
 	"github.com/gonuts/flag"
 	"github.com/jbenet/commander"
 	h "github.com/jbenet/go-ipfs/http"
@@ -14,11 +15,20 @@ var cmdIpfsServe = &commander.Command{
 	Flag:      *flag.NewFlagSet("ipfs-serve", flag.ExitOnError),
 }
 
+func init() {
+	cmdIpfsServe.Flag.Uint("port", 80, "Port number")
+}
+
 func serveCmd(c *commander.Command, _ []string) error {
+	port := c.Flag.Lookup("port").Value.Get().(uint)
+	if port < 1 || port > 65535 {
+		return errors.New("invalid port number")
+	}
+
 	n, err := localNode()
 	if err != nil {
 		return err
 	}
 
-	return h.Serve("127.0.0.1", 80, n)
+	return h.Serve("127.0.0.1", port, n)
 }

http/http.go

@@ -24,7 +24,7 @@ func (i *ipfsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprintf(w, "%s", nd.Data)
 }
 
-func Serve(host string, port uint16, node *core.IpfsNode) error {
+func Serve(host string, port uint, node *core.IpfsNode) error {
 	r := mux.NewRouter()
 	r.PathPrefix("/").Handler(&ipfsHandler{node}).Methods("GET")
 	http.Handle("/", r)