rpc/http: improve request handling

2 files changed, 102 insertions, 235 deletions

diff --git a/rpc/http.go b/rpc/http.go
index d9053b003..af3d29014 100644
--- a/rpc/http.go
+++ b/rpc/http.go
@@ -17,240 +17,23 @@
 package rpc
 
 import (
-	"bufio"
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"io"
 	"io/ioutil"
-	"net"
 	"net/http"
 	"net/url"
-	"strconv"
 	"strings"
-	"time"
 
-	"github.com/ethereum/go-ethereum/logger"
-	"github.com/ethereum/go-ethereum/logger/glog"
-	"gopkg.in/fatih/set.v0"
+	"io"
+
+	"github.com/rs/cors"
 )
 
 const (
-	httpReadDeadLine = 60 * time.Second // wait max httpReadDeadeline for next request
+	maxHTTPRequestContentLength = 1024 * 128
 )
 
-// httpMessageStream is the glue between a HTTP connection which is message based
-// and the RPC codecs that expect json requests to be read from a stream. It will
-// parse HTTP messages and offer the bodies of these requests as a stream through
-// the Read method. This will require full control of the connection and thus need
-// a "hijacked" HTTP connection.
-type httpMessageStream struct {
-	conn             net.Conn          // TCP connection
-	rw               *bufio.ReadWriter // buffered where HTTP requests/responses are read/written from/to
-	currentReq       *http.Request     // pending request, codec can pass in a too small buffer for a single read we need to keep track of the current requests if it was not read at once
-	payloadBytesRead int64             // number of bytes which are read from the current request
-	allowedOrigins   *set.Set          // allowed CORS domains
-	origin           string            // origin of this connection/request
-}
-
-// NewHttpMessageStream will create a new http message stream parser that can be
-// used by the codes in the RPC package. It will take full control of the given
-// connection and thus needs to be hijacked. It will read and write HTTP messages
-// from the passed rwbuf. The allowed origins are the RPC CORS domains the user has supplied.
-func NewHTTPMessageStream(c net.Conn, rwbuf *bufio.ReadWriter, initialReq *http.Request, allowdOrigins []string) *httpMessageStream {
-	r := &httpMessageStream{conn: c, rw: rwbuf, currentReq: initialReq, allowedOrigins: set.New()}
-	for _, origin := range allowdOrigins {
-		r.allowedOrigins.Add(origin)
-	}
-	return r
-}
-
-// handleOptionsRequest handles the HTTP preflight requests (OPTIONS) that browsers
-// make to enforce CORS rules. Only the POST method is allowed and the origin must
-// be on the rpccorsdomain list the user has specified.
-func (h *httpMessageStream) handleOptionsRequest(req *http.Request) error {
-	headers := req.Header
-
-	if !strings.EqualFold(req.Method, "OPTIONS") {
-		return fmt.Errorf("preflight aborted: %s!=OPTIONS", req.Method)
-	}
-
-	origin := headers.Get("Origin")
-	if origin == "" {
-		return fmt.Errorf("preflight aborted: empty origin")
-	}
-
-	responseHeaders := make(http.Header)
-	responseHeaders.Set("Access-Control-Allow-Methods", "POST")
-	if h.allowedOrigins.Has(origin) || h.allowedOrigins.Has("*") {
-		responseHeaders.Set("Access-Control-Allow-Origin", origin)
-	} else {
-		glog.V(logger.Info).Infof("origin '%s' not allowed", origin)
-	}
-	responseHeaders.Set("Access-Control-Allow-Headers", "Content-Type")
-	responseHeaders.Set("Date", string(httpTimestamp(time.Now())))
-	responseHeaders.Set("Content-Type", "text/plain; charset=utf-8")
-	responseHeaders.Set("Content-Length", "0")
-	responseHeaders.Set("Vary", "Origin")
-
-	defer h.rw.Flush()
-
-	if _, err := h.rw.WriteString("HTTP/1.1 200 OK\r\n"); err != nil {
-		glog.V(logger.Error).Infof("unable to write OPTIONS response: %v\n", err)
-		return err
-	}
-	if err := responseHeaders.Write(h.rw); err != nil {
-		glog.V(logger.Error).Infof("unable to write OPTIONS headers: %v\n", err)
-	}
-	if _, err := h.rw.WriteString("\r\n"); err != nil {
-		glog.V(logger.Error).Infof("unable to write OPTIONS response: %v\n", err)
-	}
-
-	return nil
-}
-
-// Read will read incoming HTTP requests and reads the body data from these requests
-// as an endless stream of data.
-func (h *httpMessageStream) Read(buf []byte) (n int, err error) {
-	h.conn.SetReadDeadline(time.Now().Add(httpReadDeadLine))
-	for {
-		// if the last request was read completely try to read the next request
-		if h.currentReq == nil {
-			if h.currentReq, err = http.ReadRequest(bufio.NewReader(h.rw)); err != nil {
-				return 0, err
-			}
-		}
-
-		// The "options" method is http specific and not interested for the RPC server.
-		// Handle it internally and wait for the next request.
-		if strings.EqualFold(h.currentReq.Method, "OPTIONS") {
-			if err = h.handleOptionsRequest(h.currentReq); err != nil {
-				glog.V(logger.Info).Infof("RPC/HTTP OPTIONS error: %v\n", err)
-				h.currentReq = nil
-				return 0, err
-			}
-
-			// processed valid request -> reset deadline
-			h.conn.SetReadDeadline(time.Now().Add(httpReadDeadLine))
-			h.currentReq = nil
-			continue
-		}
-
-		if strings.EqualFold(h.currentReq.Method, "GET") || strings.EqualFold(h.currentReq.Method, "POST") {
-			n, err := h.currentReq.Body.Read(buf)
-			h.payloadBytesRead += int64(n)
-
-			// entire payload read, read new request next time
-			if err == io.EOF || h.payloadBytesRead >= h.currentReq.ContentLength {
-				h.origin = h.currentReq.Header.Get("origin")
-				h.payloadBytesRead = 0
-				h.currentReq.Body.Close()
-				h.currentReq = nil
-				err = nil // io.EOF is not an error
-			} else if err != nil {
-				// unable to read body
-				h.currentReq.Body.Close()
-				h.currentReq = nil
-				h.payloadBytesRead = 0
-			}
-			// partial read of body
-			return n, err
-		}
-		return 0, fmt.Errorf("unsupported HTTP method '%s'", h.currentReq.Method)
-	}
-}
-
-// Write will create a HTTP response with the given payload and send it to the peer.
-func (h *httpMessageStream) Write(payload []byte) (int, error) {
-	defer h.rw.Flush()
-
-	responseHeaders := make(http.Header)
-	responseHeaders.Set("Content-Type", "application/json")
-	responseHeaders.Set("Content-Length", strconv.Itoa(len(payload)))
-	if h.origin != "" {
-		responseHeaders.Set("Access-Control-Allow-Origin", h.origin)
-	}
-
-	h.rw.WriteString("HTTP/1.1 200 OK\r\n")
-	responseHeaders.Write(h.rw)
-	h.rw.WriteString("\r\n")
-
-	return h.rw.Write(payload)
-}
-
-// Close will close the underlying TCP connection this instance has taken ownership over.
-func (h *httpMessageStream) Close() error {
-	h.rw.Flush()
-	return h.conn.Close()
-}
-
-// TimeFormat is the time format to use with time.Parse and time.Time.Format when
-// parsing or generating times in HTTP headers. It is like time.RFC1123 but hard
-// codes GMT as the time zone.
-const TimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"
-
-// httpTimestamp formats the given t as specified in RFC1123.
-func httpTimestamp(t time.Time) []byte {
-	const days = "SunMonTueWedThuFriSat"
-	const months = "JanFebMarAprMayJunJulAugSepOctNovDec"
-
-	b := make([]byte, 0)
-	t = t.UTC()
-	yy, mm, dd := t.Date()
-	hh, mn, ss := t.Clock()
-	day := days[3*t.Weekday():]
-	mon := months[3*(mm-1):]
-
-	return append(b,
-		day[0], day[1], day[2], ',', ' ',
-		byte('0'+dd/10), byte('0'+dd%10), ' ',
-		mon[0], mon[1], mon[2], ' ',
-		byte('0'+yy/1000), byte('0'+(yy/100)%10), byte('0'+(yy/10)%10), byte('0'+yy%10), ' ',
-		byte('0'+hh/10), byte('0'+hh%10), ':',
-		byte('0'+mn/10), byte('0'+mn%10), ':',
-		byte('0'+ss/10), byte('0'+ss%10), ' ',
-		'G', 'M', 'T')
-}
-
-// httpConnHijacker is a http.Handler implementation that will hijack the HTTP
-// connection,  wraps it in a HttpMessageStream that is then wrapped in a JSON
-// codec which will be served on the rpcServer.
-type httpConnHijacker struct {
-	corsdomains []string
-	rpcServer   *Server
-}
-
-// ServeHTTP will hijack the connection, wraps the captured connection in a
-// HttpMessageStream which is then used as codec.
-func (h *httpConnHijacker) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	hj, ok := w.(http.Hijacker)
-	if !ok {
-		http.Error(w, "webserver doesn't support hijacking", http.StatusInternalServerError)
-		return
-	}
-
-	conn, rwbuf, err := hj.Hijack()
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-
-	httpRequestStream := NewHTTPMessageStream(conn, rwbuf, req, h.corsdomains)
-
-	codec := NewJSONCodec(httpRequestStream)
-	go h.rpcServer.ServeCodec(codec)
-}
-
-// NewHTTPServer creates a new HTTP RPC server around an API provider.
-func NewHTTPServer(cors string, handler *Server) *http.Server {
-	return &http.Server{
-		Handler: &httpConnHijacker{
-			corsdomains: strings.Split(cors, ","),
-			rpcServer:   handler,
-		},
-	}
-}
-
 // httpClient connects to a geth RPC server over HTTP.
 type httpClient struct {
 	endpoint *url.URL // HTTP-RPC server endpoint
@@ -313,3 +96,55 @@ func (client *httpClient) Close() {
 func (client *httpClient) SupportedModules() (map[string]string, error) {
 	return SupportedModules(client)
 }
+
+// httpReadWriteNopCloser wraps a io.Reader and io.Writer with a NOP Close method.
+type httpReadWriteNopCloser struct {
+	io.Reader
+	io.Writer
+}
+
+// Close does nothing and returns always nil
+func (t *httpReadWriteNopCloser) Close() error {
+	return nil
+}
+
+// newJSONHTTPHandler creates a HTTP handler that will parse incoming JSON requests,
+// send the request to the given API provider and sends the response back to the caller.
+func newJSONHTTPHandler(srv *Server) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.ContentLength > maxHTTPRequestContentLength {
+			http.Error(w,
+				fmt.Sprintf("content length too large (%d>%d)", r.ContentLength, maxHTTPRequestContentLength),
+				http.StatusRequestEntityTooLarge)
+			return
+		}
+
+		w.Header().Set("content-type", "application/json")
+
+		// create a codec that reads direct from the request body until
+		// EOF and writes the response to w and order the server to process
+		// a single request.
+		codec := NewJSONCodec(&httpReadWriteNopCloser{r.Body, w})
+		defer codec.Close()
+		srv.ServeSingleRequest(codec)
+	}
+}
+
+// NewHTTPServer creates a new HTTP RPC server around an API provider.
+func NewHTTPServer(corsString string, srv *Server) *http.Server {
+	var allowedOrigins []string
+	for _, domain := range strings.Split(corsString, ",") {
+		allowedOrigins = append(allowedOrigins, strings.TrimSpace(domain))
+	}
+
+	c := cors.New(cors.Options{
+		AllowedOrigins: allowedOrigins,
+		AllowedMethods: []string{"POST", "GET"},
+	})
+
+	handler := c.Handler(newJSONHTTPHandler(srv))
+
+	return &http.Server{
+		Handler: handler,
+	}
+}
diff --git a/rpc/server.go b/rpc/server.go
index f42ee2d37..22448f8e3 100644
--- a/rpc/server.go
+++ b/rpc/server.go
@@ -117,14 +117,12 @@ func (s *Server) RegisterName(name string, rcvr interface{}) error {
 	return nil
 }
 
-// ServeCodec reads incoming requests from codec, calls the appropriate callback and writes the
-// response back using the given codec. It will block until the codec is closed.
-//
-// This server will:
-// 1. allow for asynchronous and parallel request execution
-// 2. supports notifications (pub/sub)
-// 3. supports request batches
-func (s *Server) ServeCodec(codec ServerCodec) {
+// serveRequest will reads requests from the codec, calls the RPC callback and
+// writes the response to the given codec.
+// If singleShot is true it will process a single request, otherwise it will handle
+// requests until the codec returns an error when reading a request (in most cases
+// an EOF). It executes requests in parallel when singleShot is false.
+func (s *Server) serveRequest(codec ServerCodec, singleShot bool) error {
 	defer func() {
 		if err := recover(); err != nil {
 			const size = 64 << 10
@@ -132,7 +130,12 @@ func (s *Server) ServeCodec(codec ServerCodec) {
 			buf = buf[:runtime.Stack(buf, false)]
 			glog.Errorln(string(buf))
 		}
-		codec.Close()
+
+		s.codecsMu.Lock()
+		s.codecs.Remove(codec)
+		s.codecsMu.Unlock()
+
+		return
 	}()
 
 	ctx, cancel := context.WithCancel(context.Background())
@@ -141,20 +144,22 @@ func (s *Server) ServeCodec(codec ServerCodec) {
 	s.codecsMu.Lock()
 	if atomic.LoadInt32(&s.run) != 1 { // server stopped
 		s.codecsMu.Unlock()
-		return
+		return &shutdownError{}
 	}
 	s.codecs.Add(codec)
 	s.codecsMu.Unlock()
 
+	// test if the server is ordered to stop
 	for atomic.LoadInt32(&s.run) == 1 {
 		reqs, batch, err := s.readRequest(codec)
-
 		if err != nil {
 			glog.V(logger.Debug).Infof("%v\n", err)
 			codec.Write(codec.CreateErrorResponse(nil, err))
-			break
+			return nil
 		}
 
+		// check if server is ordered to shutdown and return an error
+		// telling the client that his request failed.
 		if atomic.LoadInt32(&s.run) != 1 {
 			err = &shutdownError{}
 			if batch {
@@ -166,15 +171,42 @@ func (s *Server) ServeCodec(codec ServerCodec) {
 			} else {
 				codec.Write(codec.CreateErrorResponse(&reqs[0].id, err))
 			}
-			break
+			return nil
 		}
 
-		if batch {
+		if singleShot && batch {
+			s.execBatch(ctx, codec, reqs)
+			return nil
+		} else if singleShot && !batch {
+			s.exec(ctx, codec, reqs[0])
+			return nil
+		} else if !singleShot && batch {
 			go s.execBatch(ctx, codec, reqs)
 		} else {
 			go s.exec(ctx, codec, reqs[0])
 		}
 	}
+
+	return nil
+}
+
+// ServeCodec reads incoming requests from codec, calls the appropriate callback and writes the
+// response back using the given codec. It will block until the codec is closed or the server is
+// stopped. In either case the codec is closed.
+//
+// This server will:
+// 1. allow for asynchronous and parallel request execution
+// 2. supports notifications (pub/sub)
+// 3. supports request batches
+func (s *Server) ServeCodec(codec ServerCodec) {
+	defer codec.Close()
+	s.serveRequest(codec, false)
+}
+
+// ServeSingleRequest reads and processes a single RPC request from the given codec. It will not
+// close the codec unless a non-recoverable error has occurred.
+func (s *Server) ServeSingleRequest(codec ServerCodec) {
+	s.serveRequest(codec, true)
 }
 
 // Stop will stop reading new requests, wait for stopPendingRequestTimeout to allow pending requests to finish,