feat: implement http support

Signed-off-by: Kairee Wu <kaireewu@gmail.com>

server.go

@@ -4,7 +4,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"log"
 	"net"
+	"net/http"
 	"strings"
 	"sync"
 	"time"
@@ -110,3 +112,35 @@ func Register(rcvr interface{}) error {
 }
 
 func Accept(lis net.Listener) { DefaultServer.Accept(lis) }
+
+const (
+	connected = "200 Connected to kRPC"
+	defaultRPCPath = "/_krpc_"
+	defaultDebugPath = "/debug/krpc"
+)
+
+func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodConnect {
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		_, _ = fmt.Fprintln(w, "405 method not allowed")
+		return
+	}
+	conn, _, err := w.(http.Hijacker).Hijack()
+	if err != nil {
+		log.Printf("rpc hijacking %s: %s", r.RemoteAddr, err.Error())
+		return
+	}
+	_, _ = fmt.Fprintf(conn, "HTTP/1.0 %s\n\n", connected)
+	s.ServeConn(conn)
+}
+
+func (s *Server) HandleHTTP() {
+	http.Handle(defaultRPCPath, s)
+	http.Handle(defaultDebugPath, debugHTTP{s})
+	log.Println("rpc: server debug path:", defaultDebugPath)
+}
+
+func HandleHTTP() {
+	DefaultServer.HandleHTTP()
+}