cmd/geth, node: allow configuring JSON-RPC on custom path prefix (#22184)

This change allows users to set a custom path prefix on which to mount the http-rpc
or ws-rpc handlers via the new flags --http.rpcprefix and --ws.rpcprefix.

Fixes #21826

Co-authored-by: Felix Lange <fjl@twurst.com>

cmd/geth/main.go

@@ -181,6 +181,7 @@ var (
 		utils.GraphQLCORSDomainFlag,
 		utils.GraphQLVirtualHostsFlag,
 		utils.HTTPApiFlag,
+		utils.HTTPPathPrefixFlag,
 		utils.LegacyRPCApiFlag,
 		utils.WSEnabledFlag,
 		utils.WSListenAddrFlag,
@@ -190,6 +191,7 @@ var (
 		utils.WSApiFlag,
 		utils.LegacyWSApiFlag,
 		utils.WSAllowedOriginsFlag,
+		utils.WSPathPrefixFlag,
 		utils.LegacyWSAllowedOriginsFlag,
 		utils.IPCDisabledFlag,
 		utils.IPCPathFlag,

cmd/geth/usage.go

@@ -138,12 +138,14 @@ var AppHelpFlagGroups = []flags.FlagGroup{
 			utils.HTTPListenAddrFlag,
 			utils.HTTPPortFlag,
 			utils.HTTPApiFlag,
+			utils.HTTPPathPrefixFlag,
 			utils.HTTPCORSDomainFlag,
 			utils.HTTPVirtualHostsFlag,
 			utils.WSEnabledFlag,
 			utils.WSListenAddrFlag,
 			utils.WSPortFlag,
 			utils.WSApiFlag,
+			utils.WSPathPrefixFlag,
 			utils.WSAllowedOriginsFlag,
 			utils.GraphQLEnabledFlag,
 			utils.GraphQLCORSDomainFlag,

cmd/utils/flags.go

@@ -531,6 +531,11 @@ var (
 		Usage: "API's offered over the HTTP-RPC interface",
 		Value: "",
 	}
+	HTTPPathPrefixFlag = cli.StringFlag{
+		Name:  "http.rpcprefix",
+		Usage: "HTTP path path prefix on which JSON-RPC is served. Use '/' to serve on all paths.",
+		Value: "",
+	}
 	GraphQLEnabledFlag = cli.BoolFlag{
 		Name:  "graphql",
 		Usage: "Enable GraphQL on the HTTP-RPC server. Note that GraphQL can only be started if an HTTP server is started as well.",
@@ -569,6 +574,11 @@ var (
 		Usage: "Origins from which to accept websockets requests",
 		Value: "",
 	}
+	WSPathPrefixFlag = cli.StringFlag{
+		Name:  "ws.rpcprefix",
+		Usage: "HTTP path prefix on which JSON-RPC is served. Use '/' to serve on all paths.",
+		Value: "",
+	}
 	ExecFlag = cli.StringFlag{
 		Name:  "exec",
 		Usage: "Execute JavaScript statement",
@@ -946,6 +956,10 @@ func setHTTP(ctx *cli.Context, cfg *node.Config) {
 	if ctx.GlobalIsSet(HTTPVirtualHostsFlag.Name) {
 		cfg.HTTPVirtualHosts = SplitAndTrim(ctx.GlobalString(HTTPVirtualHostsFlag.Name))
 	}
+
+	if ctx.GlobalIsSet(HTTPPathPrefixFlag.Name) {
+		cfg.HTTPPathPrefix = ctx.GlobalString(HTTPPathPrefixFlag.Name)
+	}
 }
 
 // setGraphQL creates the GraphQL listener interface string from the set
@@ -995,6 +1009,10 @@ func setWS(ctx *cli.Context, cfg *node.Config) {
 	if ctx.GlobalIsSet(WSApiFlag.Name) {
 		cfg.WSModules = SplitAndTrim(ctx.GlobalString(WSApiFlag.Name))
 	}
+
+	if ctx.GlobalIsSet(WSPathPrefixFlag.Name) {
+		cfg.WSPathPrefix = ctx.GlobalString(WSPathPrefixFlag.Name)
+	}
 }
 
 // setIPC creates an IPC path configuration from the set command line flags,

go.sum

@@ -433,7 +433,6 @@ golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4Iltr
 golang.org/x/oauth2 v0.0.0-20191202225959-858c2ad4c8b6/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20181108010431-42b317875d0f h1:Bl/8QSvNqXvPGPGXa2z5xUTmV7VDcZyvRZ+QQXkXTZQ=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -501,7 +500,6 @@ golang.org/x/tools v0.0.0-20200108203644-89082a384178/go.mod h1:TB2adYChydJhpapK
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.0.0-20180816165407-929014505bf4/go.mod h1:Y+Yx5eoAFn32cQvJDxZx5Dpnq+c3wtXuadVZAcxbbBo=
 gonum.org/v1/gonum v0.0.0-20181121035319-3f7ecaa7e8ca/go.mod h1:Y+Yx5eoAFn32cQvJDxZx5Dpnq+c3wtXuadVZAcxbbBo=
@@ -549,15 +547,12 @@ google.golang.org/protobuf v1.23.0 h1:4MY060fB1DLGMB/7MBTLnwQUY6+F09GEiz6SsrNqyz
 google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/fsnotify.v1 v1.4.7/go.mod h1:Tz8NjZHkW78fSQdbUxIjBTcgA1z1m8ZHf0WmKUhAMys=
-gopkg.in/natefinch/npipe.v2 v2.0.0-20160621034901-c1b8fa8bdcce h1:+JknDZhAj8YMt7GC73Ei8pv4MzjDUNPHgQWJdtMAaDU=
 gopkg.in/natefinch/npipe.v2 v2.0.0-20160621034901-c1b8fa8bdcce/go.mod h1:5AcXVHNjg+BDxry382+8OKon8SEWiKktQR07RKPsv1c=
 gopkg.in/olebedev/go-duktape.v3 v3.0.0-20200619000410-60c24ae608a6 h1:a6cXbcDDUkSBlpnkWV1bJ+vv3mOgQEltEJ2rPxroVu0=
 gopkg.in/olebedev/go-duktape.v3 v3.0.0-20200619000410-60c24ae608a6/go.mod h1:uAJfkITjFhyEEuUfm7bsmCZRbW5WRq8s9EY8HZ6hCns=
-gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7 h1:uRGJdciOHaEIrze2W8Q3AKkepLTh2hOroT7a+7czfdQ=
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
 gopkg.in/urfave/cli.v1 v1.20.0 h1:NdAVW6RYxDif9DhDHaAortIu956m2c0v+09AZBPTbE0=
 gopkg.in/urfave/cli.v1 v1.20.0/go.mod h1:vuBzUtMdQeixQj8LVd+/98pzhxNGQoyuPBlsXHOQNO0=

graphql/graphql_test.go

@@ -30,6 +30,8 @@ import (
 	"github.com/ethereum/go-ethereum/eth"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/params"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestBuildSchema(t *testing.T) {
@@ -166,18 +168,8 @@ func TestGraphQLHTTPOnSamePort_GQLRequest_Unsuccessful(t *testing.T) {
 	if err != nil {
 		t.Fatalf("could not post: %v", err)
 	}
-	bodyBytes, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		t.Fatalf("could not read from response body: %v", err)
-	}
-	resp.Body.Close()
 	// make sure the request is not handled successfully
-	if want, have := "404 page not found\n", string(bodyBytes); have != want {
+	assert.Equal(t, http.StatusNotFound, resp.StatusCode)
-		t.Errorf("have:\n%v\nwant:\n%v", have, want)
-	}
-	if want, have := 404, resp.StatusCode; want != have {
-		t.Errorf("wrong statuscode, have:\n%v\nwant:%v", have, want)
-	}
 }
 
 func createNode(t *testing.T, gqlEnabled bool) *node.Node {

node/api_test.go

@@ -244,7 +244,10 @@ func TestStartRPC(t *testing.T) {
 	}
 
 	for _, test := range tests {
+		test := test
 		t.Run(test.name, func(t *testing.T) {
+			t.Parallel()
+
 			// Apply some sane defaults.
 			config := test.cfg
 			// config.Logger = testlog.Logger(t, log.LvlDebug)

node/config.go

@@ -139,6 +139,9 @@ type Config struct {
 	// interface.
 	HTTPTimeouts rpc.HTTPTimeouts
 
+	// HTTPPathPrefix specifies a path prefix on which http-rpc is to be served.
+	HTTPPathPrefix string `toml:",omitempty"`
+
 	// WSHost is the host interface on which to start the websocket RPC server. If
 	// this field is empty, no websocket API endpoint will be started.
 	WSHost string
@@ -148,6 +151,9 @@ type Config struct {
 	// ephemeral nodes).
 	WSPort int `toml:",omitempty"`
 
+	// WSPathPrefix specifies a path prefix on which ws-rpc is to be served.
+	WSPathPrefix string `toml:",omitempty"`
+
 	// WSOrigins is the list of domain to accept websocket requests from. Please be
 	// aware that the server can only act upon the HTTP request the client sends and
 	// cannot verify the validity of the request header.

node/node.go

@@ -135,6 +135,14 @@ func New(conf *Config) (*Node, error) {
 		node.server.Config.NodeDatabase = node.config.NodeDB()
 	}
 
+	// Check HTTP/WS prefixes are valid.
+	if err := validatePrefix("HTTP", conf.HTTPPathPrefix); err != nil {
+		return nil, err
+	}
+	if err := validatePrefix("WebSocket", conf.WSPathPrefix); err != nil {
+		return nil, err
+	}
+
 	// Configure RPC servers.
 	node.http = newHTTPServer(node.log, conf.HTTPTimeouts)
 	node.ws = newHTTPServer(node.log, rpc.DefaultHTTPTimeouts)
@@ -346,6 +354,7 @@ func (n *Node) startRPC() error {
 			CorsAllowedOrigins: n.config.HTTPCors,
 			Vhosts:             n.config.HTTPVirtualHosts,
 			Modules:            n.config.HTTPModules,
+			prefix:             n.config.HTTPPathPrefix,
 		}
 		if err := n.http.setListenAddr(n.config.HTTPHost, n.config.HTTPPort); err != nil {
 			return err
@@ -361,6 +370,7 @@ func (n *Node) startRPC() error {
 		config := wsConfig{
 			Modules: n.config.WSModules,
 			Origins: n.config.WSOrigins,
+			prefix:  n.config.WSPathPrefix,
 		}
 		if err := server.setListenAddr(n.config.WSHost, n.config.WSPort); err != nil {
 			return err
@@ -457,6 +467,7 @@ func (n *Node) RegisterHandler(name, path string, handler http.Handler) {
 	if n.state != initializingState {
 		panic("can't register HTTP handler on running/stopped node")
 	}
+
 	n.http.mux.Handle(path, handler)
 	n.http.handlerNames[path] = name
 }
@@ -513,17 +524,18 @@ func (n *Node) IPCEndpoint() string {
 	return n.ipc.endpoint
 }
 
-// HTTPEndpoint returns the URL of the HTTP server.
+// HTTPEndpoint returns the URL of the HTTP server. Note that this URL does not
+// contain the JSON-RPC path prefix set by HTTPPathPrefix.
 func (n *Node) HTTPEndpoint() string {
 	return "http://" + n.http.listenAddr()
 }
 
-// WSEndpoint retrieves the current WS endpoint used by the protocol stack.
+// WSEndpoint returns the current JSON-RPC over WebSocket endpoint.
 func (n *Node) WSEndpoint() string {
 	if n.http.wsAllowed() {
-		return "ws://" + n.http.listenAddr()
+		return "ws://" + n.http.listenAddr() + n.http.wsConfig.prefix
 	}
-	return "ws://" + n.ws.listenAddr()
+	return "ws://" + n.ws.listenAddr() + n.ws.wsConfig.prefix
 }
 
 // EventMux retrieves the event multiplexer used by all the network services in

node/node_test.go

@@ -390,7 +390,7 @@ func TestLifecycleTerminationGuarantee(t *testing.T) {
 }
 
 // Tests whether a handler can be successfully mounted on the canonical HTTP server
-// on the given path
+// on the given prefix
 func TestRegisterHandler_Successful(t *testing.T) {
 	node := createNode(t, 7878, 7979)
 
@@ -483,7 +483,112 @@ func TestWebsocketHTTPOnSeparatePort_WSRequest(t *testing.T) {
 	if !checkRPC(node.HTTPEndpoint()) {
 		t.Fatalf("http request failed")
 	}
+}
 
+type rpcPrefixTest struct {
+	httpPrefix, wsPrefix string
+	// These lists paths on which JSON-RPC should be served / not served.
+	wantHTTP   []string
+	wantNoHTTP []string
+	wantWS     []string
+	wantNoWS   []string
+}
+
+func TestNodeRPCPrefix(t *testing.T) {
+	t.Parallel()
+
+	tests := []rpcPrefixTest{
+		// both off
+		{
+			httpPrefix: "", wsPrefix: "",
+			wantHTTP:   []string{"/", "/?p=1"},
+			wantNoHTTP: []string{"/test", "/test?p=1"},
+			wantWS:     []string{"/", "/?p=1"},
+			wantNoWS:   []string{"/test", "/test?p=1"},
+		},
+		// only http prefix
+		{
+			httpPrefix: "/testprefix", wsPrefix: "",
+			wantHTTP:   []string{"/testprefix", "/testprefix?p=1", "/testprefix/x", "/testprefix/x?p=1"},
+			wantNoHTTP: []string{"/", "/?p=1", "/test", "/test?p=1"},
+			wantWS:     []string{"/", "/?p=1"},
+			wantNoWS:   []string{"/testprefix", "/testprefix?p=1", "/test", "/test?p=1"},
+		},
+		// only ws prefix
+		{
+			httpPrefix: "", wsPrefix: "/testprefix",
+			wantHTTP:   []string{"/", "/?p=1"},
+			wantNoHTTP: []string{"/testprefix", "/testprefix?p=1", "/test", "/test?p=1"},
+			wantWS:     []string{"/testprefix", "/testprefix?p=1", "/testprefix/x", "/testprefix/x?p=1"},
+			wantNoWS:   []string{"/", "/?p=1", "/test", "/test?p=1"},
+		},
+		// both set
+		{
+			httpPrefix: "/testprefix", wsPrefix: "/testprefix",
+			wantHTTP:   []string{"/testprefix", "/testprefix?p=1", "/testprefix/x", "/testprefix/x?p=1"},
+			wantNoHTTP: []string{"/", "/?p=1", "/test", "/test?p=1"},
+			wantWS:     []string{"/testprefix", "/testprefix?p=1", "/testprefix/x", "/testprefix/x?p=1"},
+			wantNoWS:   []string{"/", "/?p=1", "/test", "/test?p=1"},
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		name := fmt.Sprintf("http=%s ws=%s", test.httpPrefix, test.wsPrefix)
+		t.Run(name, func(t *testing.T) {
+			cfg := &Config{
+				HTTPHost:       "127.0.0.1",
+				HTTPPathPrefix: test.httpPrefix,
+				WSHost:         "127.0.0.1",
+				WSPathPrefix:   test.wsPrefix,
+			}
+			node, err := New(cfg)
+			if err != nil {
+				t.Fatal("can't create node:", err)
+			}
+			defer node.Close()
+			if err := node.Start(); err != nil {
+				t.Fatal("can't start node:", err)
+			}
+			test.check(t, node)
+		})
+	}
+}
+
+func (test rpcPrefixTest) check(t *testing.T, node *Node) {
+	t.Helper()
+	httpBase := "http://" + node.http.listenAddr()
+	wsBase := "ws://" + node.http.listenAddr()
+
+	if node.WSEndpoint() != wsBase+test.wsPrefix {
+		t.Errorf("Error: node has wrong WSEndpoint %q", node.WSEndpoint())
+	}
+
+	for _, path := range test.wantHTTP {
+		resp := rpcRequest(t, httpBase+path)
+		if resp.StatusCode != 200 {
+			t.Errorf("Error: %s: bad status code %d, want 200", path, resp.StatusCode)
+		}
+	}
+	for _, path := range test.wantNoHTTP {
+		resp := rpcRequest(t, httpBase+path)
+		if resp.StatusCode != 404 {
+			t.Errorf("Error: %s: bad status code %d, want 404", path, resp.StatusCode)
+		}
+	}
+	for _, path := range test.wantWS {
+		err := wsRequest(t, wsBase+path, "")
+		if err != nil {
+			t.Errorf("Error: %s: WebSocket connection failed: %v", path, err)
+		}
+	}
+	for _, path := range test.wantNoWS {
+		err := wsRequest(t, wsBase+path, "")
+		if err == nil {
+			t.Errorf("Error: %s: WebSocket connection succeeded for path in wantNoWS", path)
+		}
+
+	}
 }
 
 func createNode(t *testing.T, httpPort, wsPort int) *Node {

node/rpcstack.go

@@ -39,12 +39,14 @@ type httpConfig struct {
 	Modules            []string
 	CorsAllowedOrigins []string
 	Vhosts             []string
+	prefix             string // path prefix on which to mount http handler
 }
 
 // wsConfig is the JSON-RPC/Websocket configuration
 type wsConfig struct {
 	Origins []string
 	Modules []string
+	prefix  string // path prefix on which to mount ws handler
 }
 
 type rpcHandler struct {
@@ -62,6 +64,7 @@ type httpServer struct {
 	listener net.Listener // non-nil when server is running
 
 	// HTTP RPC handler things.
+
 	httpConfig  httpConfig
 	httpHandler atomic.Value // *rpcHandler
 
@@ -79,6 +82,7 @@ type httpServer struct {
 
 func newHTTPServer(log log.Logger, timeouts rpc.HTTPTimeouts) *httpServer {
 	h := &httpServer{log: log, timeouts: timeouts, handlerNames: make(map[string]string)}
+
 	h.httpHandler.Store((*rpcHandler)(nil))
 	h.wsHandler.Store((*rpcHandler)(nil))
 	return h
@@ -142,12 +146,17 @@ func (h *httpServer) start() error {
 
 	// if server is websocket only, return after logging
 	if h.wsAllowed() && !h.rpcAllowed() {
-		h.log.Info("WebSocket enabled", "url", fmt.Sprintf("ws://%v", listener.Addr()))
+		url := fmt.Sprintf("ws://%v", listener.Addr())
+		if h.wsConfig.prefix != "" {
+			url += h.wsConfig.prefix
+		}
+		h.log.Info("WebSocket enabled", "url", url)
 		return nil
 	}
 	// Log http endpoint.
 	h.log.Info("HTTP server started",
 		"endpoint", listener.Addr(),
+		"prefix", h.httpConfig.prefix,
 		"cors", strings.Join(h.httpConfig.CorsAllowedOrigins, ","),
 		"vhosts", strings.Join(h.httpConfig.Vhosts, ","),
 	)
@@ -170,26 +179,60 @@ func (h *httpServer) start() error {
 }
 
 func (h *httpServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	rpc := h.httpHandler.Load().(*rpcHandler)
+	// check if ws request and serve if ws enabled
-	if r.RequestURI == "/" {
+	ws := h.wsHandler.Load().(*rpcHandler)
-		// Serve JSON-RPC on the root path.
+	if ws != nil && isWebsocket(r) {
-		ws := h.wsHandler.Load().(*rpcHandler)
+		if checkPath(r, h.wsConfig.prefix) {
-		if ws != nil && isWebsocket(r) {
 			ws.ServeHTTP(w, r)
-			return
 		}
-		if rpc != nil {
+		return
-			rpc.ServeHTTP(w, r)
+	}
-			return
+	// if http-rpc is enabled, try to serve request
-		}
+	rpc := h.httpHandler.Load().(*rpcHandler)
-	} else if rpc != nil {
+	if rpc != nil {
+		// First try to route in the mux.
 		// Requests to a path below root are handled by the mux,
 		// which has all the handlers registered via Node.RegisterHandler.
 		// These are made available when RPC is enabled.
-		h.mux.ServeHTTP(w, r)
+		muxHandler, pattern := h.mux.Handler(r)
-		return
+		if pattern != "" {
+			muxHandler.ServeHTTP(w, r)
+			return
+		}
+
+		if checkPath(r, h.httpConfig.prefix) {
+			rpc.ServeHTTP(w, r)
+			return
+		}
 	}
-	w.WriteHeader(404)
+	w.WriteHeader(http.StatusNotFound)
+}
+
+// checkPath checks whether a given request URL matches a given path prefix.
+func checkPath(r *http.Request, path string) bool {
+	// if no prefix has been specified, request URL must be on root
+	if path == "" {
+		return r.URL.Path == "/"
+	}
+	// otherwise, check to make sure prefix matches
+	return len(r.URL.Path) >= len(path) && r.URL.Path[:len(path)] == path
+}
+
+// validatePrefix checks if 'path' is a valid configuration value for the RPC prefix option.
+func validatePrefix(what, path string) error {
+	if path == "" {
+		return nil
+	}
+	if path[0] != '/' {
+		return fmt.Errorf(`%s RPC path prefix %q does not contain leading "/"`, what, path)
+	}
+	if strings.ContainsAny(path, "?#") {
+		// This is just to avoid confusion. While these would match correctly (i.e. they'd
+		// match if URL-escaped into path), it's not easy to understand for users when
+		// setting that on the command line.
+		return fmt.Errorf("%s RPC path prefix %q contains URL meta-characters", what, path)
+	}
+	return nil
 }
 
 // stop shuts down the HTTP server.

node/rpcstack_test.go

@@ -18,7 +18,10 @@ package node
 
 import (
 	"bytes"
+	"fmt"
 	"net/http"
+	"net/url"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -31,25 +34,27 @@ import (
 
 // TestCorsHandler makes sure CORS are properly handled on the http server.
 func TestCorsHandler(t *testing.T) {
-	srv := createAndStartServer(t, httpConfig{CorsAllowedOrigins: []string{"test", "test.com"}}, false, wsConfig{})
+	srv := createAndStartServer(t, &httpConfig{CorsAllowedOrigins: []string{"test", "test.com"}}, false, &wsConfig{})
 	defer srv.stop()
+	url := "http://" + srv.listenAddr()
 
-	resp := testRequest(t, "origin", "test.com", "", srv)
+	resp := rpcRequest(t, url, "origin", "test.com")
 	assert.Equal(t, "test.com", resp.Header.Get("Access-Control-Allow-Origin"))
 
-	resp2 := testRequest(t, "origin", "bad", "", srv)
+	resp2 := rpcRequest(t, url, "origin", "bad")
 	assert.Equal(t, "", resp2.Header.Get("Access-Control-Allow-Origin"))
 }
 
 // TestVhosts makes sure vhosts are properly handled on the http server.
 func TestVhosts(t *testing.T) {
-	srv := createAndStartServer(t, httpConfig{Vhosts: []string{"test"}}, false, wsConfig{})
+	srv := createAndStartServer(t, &httpConfig{Vhosts: []string{"test"}}, false, &wsConfig{})
 	defer srv.stop()
+	url := "http://" + srv.listenAddr()
 
-	resp := testRequest(t, "", "", "test", srv)
+	resp := rpcRequest(t, url, "host", "test")
 	assert.Equal(t, resp.StatusCode, http.StatusOK)
 
-	resp2 := testRequest(t, "", "", "bad", srv)
+	resp2 := rpcRequest(t, url, "host", "bad")
 	assert.Equal(t, resp2.StatusCode, http.StatusForbidden)
 }
 
@@ -138,14 +143,15 @@ func TestWebsocketOrigins(t *testing.T) {
 		},
 	}
 	for _, tc := range tests {
-		srv := createAndStartServer(t, httpConfig{}, true, wsConfig{Origins: splitAndTrim(tc.spec)})
+		srv := createAndStartServer(t, &httpConfig{}, true, &wsConfig{Origins: splitAndTrim(tc.spec)})
+		url := fmt.Sprintf("ws://%v", srv.listenAddr())
 		for _, origin := range tc.expOk {
-			if err := attemptWebsocketConnectionFromOrigin(t, srv, origin); err != nil {
+			if err := wsRequest(t, url, origin); err != nil {
 				t.Errorf("spec '%v', origin '%v': expected ok, got %v", tc.spec, origin, err)
 			}
 		}
 		for _, origin := range tc.expFail {
-			if err := attemptWebsocketConnectionFromOrigin(t, srv, origin); err == nil {
+			if err := wsRequest(t, url, origin); err == nil {
 				t.Errorf("spec '%v', origin '%v': expected not to allow,  got ok", tc.spec, origin)
 			}
 		}
@@ -168,47 +174,118 @@ func TestIsWebsocket(t *testing.T) {
 	assert.True(t, isWebsocket(r))
 }
 
-func createAndStartServer(t *testing.T, conf httpConfig, ws bool, wsConf wsConfig) *httpServer {
+func Test_checkPath(t *testing.T) {
+	tests := []struct {
+		req      *http.Request
+		prefix   string
+		expected bool
+	}{
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/test"}},
+			prefix:   "/test",
+			expected: true,
+		},
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/testing"}},
+			prefix:   "/test",
+			expected: true,
+		},
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/"}},
+			prefix:   "/test",
+			expected: false,
+		},
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/fail"}},
+			prefix:   "/test",
+			expected: false,
+		},
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/"}},
+			prefix:   "",
+			expected: true,
+		},
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/fail"}},
+			prefix:   "",
+			expected: false,
+		},
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/"}},
+			prefix:   "/",
+			expected: true,
+		},
+		{
+			req:      &http.Request{URL: &url.URL{Path: "/testing"}},
+			prefix:   "/",
+			expected: true,
+		},
+	}
+
+	for i, tt := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			assert.Equal(t, tt.expected, checkPath(tt.req, tt.prefix))
+		})
+	}
+}
+
+func createAndStartServer(t *testing.T, conf *httpConfig, ws bool, wsConf *wsConfig) *httpServer {
 	t.Helper()
 
 	srv := newHTTPServer(testlog.Logger(t, log.LvlDebug), rpc.DefaultHTTPTimeouts)
-
+	assert.NoError(t, srv.enableRPC(nil, *conf))
-	assert.NoError(t, srv.enableRPC(nil, conf))
 	if ws {
-		assert.NoError(t, srv.enableWS(nil, wsConf))
+		assert.NoError(t, srv.enableWS(nil, *wsConf))
 	}
 	assert.NoError(t, srv.setListenAddr("localhost", 0))
 	assert.NoError(t, srv.start())
-
 	return srv
 }
 
-func attemptWebsocketConnectionFromOrigin(t *testing.T, srv *httpServer, browserOrigin string) error {
+// wsRequest attempts to open a WebSocket connection to the given URL.
+func wsRequest(t *testing.T, url, browserOrigin string) error {
 	t.Helper()
-	dialer := websocket.DefaultDialer
+	t.Logf("checking WebSocket on %s (origin %q)", url, browserOrigin)
-	_, _, err := dialer.Dial("ws://"+srv.listenAddr(), http.Header{
+
-		"Content-type":          []string{"application/json"},
+	headers := make(http.Header)
-		"Sec-WebSocket-Version": []string{"13"},
+	if browserOrigin != "" {
-		"Origin":                []string{browserOrigin},
+		headers.Set("Origin", browserOrigin)
-	})
+	}
+	conn, _, err := websocket.DefaultDialer.Dial(url, headers)
+	if conn != nil {
+		conn.Close()
+	}
 	return err
 }
 
-func testRequest(t *testing.T, key, value, host string, srv *httpServer) *http.Response {
+// rpcRequest performs a JSON-RPC request to the given URL.
+func rpcRequest(t *testing.T, url string, extraHeaders ...string) *http.Response {
 	t.Helper()
 
-	body := bytes.NewReader([]byte(`{"jsonrpc":"2.0","id":1,method":"rpc_modules"}`))
+	// Create the request.
-	req, _ := http.NewRequest("POST", "http://"+srv.listenAddr(), body)
+	body := bytes.NewReader([]byte(`{"jsonrpc":"2.0","id":1,"method":"rpc_modules","params":[]}`))
-	req.Header.Set("content-type", "application/json")
+	req, err := http.NewRequest("POST", url, body)
-	if key != "" && value != "" {
+	if err != nil {
-		req.Header.Set(key, value)
+		t.Fatal("could not create http request:", err)
 	}
-	if host != "" {
+	req.Header.Set("content-type", "application/json")
-		req.Host = host
+
+	// Apply extra headers.
+	if len(extraHeaders)%2 != 0 {
+		panic("odd extraHeaders length")
+	}
+	for i := 0; i < len(extraHeaders); i += 2 {
+		key, value := extraHeaders[i], extraHeaders[i+1]
+		if strings.ToLower(key) == "host" {
+			req.Host = value
+		} else {
+			req.Header.Set(key, value)
+		}
 	}
 
-	client := http.DefaultClient
+	// Perform the request.
-	resp, err := client.Do(req)
+	t.Logf("checking RPC/HTTP on %s %v", url, extraHeaders)
+	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		t.Fatal(err)
 	}