server/prpc: updated server according to protocol

server/prpc/server.go

Index: server/prpc/server.go
diff --git a/server/prpc/server.go b/server/prpc/server.go
index df43971e712a79a6b1a1ac4ed34302ea92bf26fd..202aa1c20d8543984b69d9bacb7d29403a064f45 100644
--- a/server/prpc/server.go
+++ b/server/prpc/server.go
@@ -5,6 +5,7 @@
 package prpc
 
 import (
+	"fmt"
 	"net/http"
 	"sort"
 	"sync"
@@ -12,7 +13,9 @@ import (
 	"github.com/julienschmidt/httprouter"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 
+	"github.com/luci/luci-go/common/logging"
 	"github.com/luci/luci-go/server/auth"
 	"github.com/luci/luci-go/server/middleware"
 )
@@ -55,7 +58,7 @@ func (s *Server) RegisterService(desc *grpc.ServiceDesc, impl interface{}) {
 	if s.services == nil {
 		s.services = map[string]*service{}
 	} else if _, ok := s.services[desc.ServiceName]; ok {
-		panicf("service %q is already registered", desc.ServiceName)
+		panic(fmt.Errorf("service %q is already registered", desc.ServiceName))
 	}
 
 	s.services[desc.ServiceName] = serv
@@ -65,7 +68,7 @@ func (s *Server) RegisterService(desc *grpc.ServiceDesc, impl interface{}) {
 func (s *Server) authenticate(base middleware.Base) middleware.Base {
 	a := GetDefaultAuth()
 	if a == nil {
-		panicf("prpc: CustomAuthenticator is false, but default authenticator was not registered. " +
+		panic("prpc: CustomAuthenticator is false, but default authenticator was not registered. " +
 			"Forgot to import appengine/gaeauth/server package?")
 	}
 
@@ -74,7 +77,8 @@ func (s *Server) authenticate(base middleware.Base) middleware.Base {
 			c = auth.SetAuthenticator(c, a)
 			c, err := a.Authenticate(c, r)
 			if err != nil {
-				writeError(c, w, withStatus(err, http.StatusUnauthorized))
+				res := errResponse(codes.Unauthenticated, http.StatusUnauthorized, escapeFmt(err.Error()))
+				res.write(c, w)
 				return
 			}
 			h(c, w, r, p)
@@ -82,8 +86,9 @@ func (s *Server) authenticate(base middleware.Base) middleware.Base {
 	}
 }
 
-// InstallHandlers installs HTTP POST handlers at
-// /prpc/{service_name}/{method_name} for all registered services.
+// InstallHandlers installs HTTP handlers at /prpc/:service/:method.
+// See https://godoc.org/github.com/luci/luci-go/common/prpc#hdr-Protocol
+// for pRPC protocol.
 func (s *Server) InstallHandlers(r *httprouter.Router, base middleware.Base) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -92,11 +97,45 @@ func (s *Server) InstallHandlers(r *httprouter.Router, base middleware.Base) {
 		base = s.authenticate(base)
 	}
 
-	for _, service := range s.services {
-		for _, m := range service.methods {
-			m.InstallHandlers(r, base)
-		}
+	r.POST("/prpc/:service/:method", base(s.handle))
+}
+
+// handle handles RPCs.
+// See https://godoc.org/github.com/luci/luci-go/common/prpc#hdr-Protocol
+// for pRPC protocol.
+func (s *Server) handle(c context.Context, w http.ResponseWriter, r *http.Request, p httprouter.Params) {
+	serviceName := p.ByName("service")
+	methodName := p.ByName("method")
+	res := s.respond(c, w, r, serviceName, methodName)
+
+	c = logging.SetFields(c, logging.Fields{
+		"service": serviceName,
+		"method":  methodName,
+	})
+	res.write(c, w)
+}
+
+func (s *Server) respond(c context.Context, w http.ResponseWriter, r *http.Request, serviceName, methodName string) *response {
+	service := s.services[serviceName]
+	if service == nil {
+		return errResponse(
+			codes.Unimplemented,
+			http.StatusNotImplemented,
+			"service %q is not implemented",
+			serviceName)
+	}
+
+	method := service.methods[methodName]
+	if method == nil {
+		return errResponse(
+			codes.Unimplemented,
+			http.StatusNotImplemented,
+			"method %q in service %q is not implemented",
+			methodName,
+			serviceName)
 	}
+
+	return method.handle(c, w, r)
 }
 
 // ServiceNames returns a sorted list of full names of all registered services.