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// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rpc
import (
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"mime"
"net"
"net/http"
"strings"
"sync"
"time"
"github.com/ethereum/go-ethereum/log"
"github.com/rs/cors"
)
const (
maxRequestContentLength = 1024 * 512
contentType = "application/json"
)
// https://www.jsonrpc.org/historical/json-rpc-over-http.html#id13
var acceptedContentTypes = []string{contentType, "application/json-rpc", "application/jsonrequest"}
type httpConn struct {
client *http.Client
req *http.Request
closeOnce sync.Once
closed chan interface{}
}
// httpConn is treated specially by Client.
func (hc *httpConn) Write(context.Context, interface{}) error {
panic("Write called on httpConn")
}
func (hc *httpConn) RemoteAddr() string {
return hc.req.URL.String()
}
func (hc *httpConn) Read() ([]*jsonrpcMessage, bool, error) {
<-hc.closed
return nil, false, io.EOF
}
func (hc *httpConn) Close() {
hc.closeOnce.Do(func() { close(hc.closed) })
}
func (hc *httpConn) Closed() <-chan interface{} {
return hc.closed
}
// HTTPTimeouts represents the configuration params for the HTTP RPC server.
type HTTPTimeouts struct {
// ReadTimeout is the maximum duration for reading the entire
// request, including the body.
//
// Because ReadTimeout does not let Handlers make per-request
// decisions on each request body's acceptable deadline or
// upload rate, most users will prefer to use
// ReadHeaderTimeout. It is valid to use them both.
ReadTimeout time.Duration
// WriteTimeout is the maximum duration before timing out
// writes of the response. It is reset whenever a new
// request's header is read. Like ReadTimeout, it does not
// let Handlers make decisions on a per-request basis.
WriteTimeout time.Duration
// IdleTimeout is the maximum amount of time to wait for the
// next request when keep-alives are enabled. If IdleTimeout
// is zero, the value of ReadTimeout is used. If both are
// zero, ReadHeaderTimeout is used.
IdleTimeout time.Duration
}
// DefaultHTTPTimeouts represents the default timeout values used if further
// configuration is not provided.
var DefaultHTTPTimeouts = HTTPTimeouts{
ReadTimeout: 30 * time.Second,
WriteTimeout: 30 * time.Second,
IdleTimeout: 120 * time.Second,
}
// DialHTTPWithClient creates a new RPC client that connects to an RPC server over HTTP
// using the provided HTTP Client.
func DialHTTPWithClient(endpoint string, client *http.Client) (*Client, error) {
req, err := http.NewRequest(http.MethodPost, endpoint, nil)
if err != nil {
return nil, err
}
req.Header.Set("Content-Type", contentType)
req.Header.Set("Accept", contentType)
initctx := context.Background()
return newClient(initctx, func(context.Context) (ServerCodec, error) {
return &httpConn{client: client, req: req, closed: make(chan interface{})}, nil
})
}
// DialHTTP creates a new RPC client that connects to an RPC server over HTTP.
func DialHTTP(endpoint string) (*Client, error) {
return DialHTTPWithClient(endpoint, new(http.Client))
}
func (c *Client) sendHTTP(ctx context.Context, op *requestOp, msg interface{}) error {
hc := c.writeConn.(*httpConn)
respBody, err := hc.doRequest(ctx, msg)
if respBody != nil {
defer respBody.Close()
}
if err != nil {
if respBody != nil {
buf := new(bytes.Buffer)
if _, err2 := buf.ReadFrom(respBody); err2 == nil {
return fmt.Errorf("%v %v", err, buf.String())
}
}
return err
}
var respmsg jsonrpcMessage
if err := json.NewDecoder(respBody).Decode(&respmsg); err != nil {
return err
}
op.resp <- &respmsg
return nil
}
func (c *Client) sendBatchHTTP(ctx context.Context, op *requestOp, msgs []*jsonrpcMessage) error {
hc := c.writeConn.(*httpConn)
respBody, err := hc.doRequest(ctx, msgs)
if err != nil {
return err
}
defer respBody.Close()
var respmsgs []jsonrpcMessage
if err := json.NewDecoder(respBody).Decode(&respmsgs); err != nil {
return err
}
for i := 0; i < len(respmsgs); i++ {
op.resp <- &respmsgs[i]
}
return nil
}
func (hc *httpConn) doRequest(ctx context.Context, msg interface{}) (io.ReadCloser, error) {
body, err := json.Marshal(msg)
if err != nil {
return nil, err
}
req := hc.req.WithContext(ctx)
req.Body = ioutil.NopCloser(bytes.NewReader(body))
req.ContentLength = int64(len(body))
resp, err := hc.client.Do(req)
if err != nil {
return nil, err
}
if resp.StatusCode < 200 || resp.StatusCode >= 300 {
return resp.Body, errors.New(resp.Status)
}
return resp.Body, nil
}
// httpServerConn turns a HTTP connection into a Conn.
type httpServerConn struct {
io.Reader
io.Writer
r *http.Request
}
func newHTTPServerConn(r *http.Request, w http.ResponseWriter) ServerCodec {
body := io.LimitReader(r.Body, maxRequestContentLength)
conn := &httpServerConn{Reader: body, Writer: w, r: r}
return NewJSONCodec(conn)
}
// Close does nothing and always returns nil.
func (t *httpServerConn) Close() error { return nil }
// RemoteAddr returns the peer address of the underlying connection.
func (t *httpServerConn) RemoteAddr() string {
return t.r.RemoteAddr
}
// SetWriteDeadline does nothing and always returns nil.
func (t *httpServerConn) SetWriteDeadline(time.Time) error { return nil }
// NewHTTPServer creates a new HTTP RPC server around an API provider.
//
// Deprecated: Server implements http.Handler
func NewHTTPServer(cors []string, vhosts []string, timeouts HTTPTimeouts, srv http.Handler) *http.Server {
// Wrap the CORS-handler within a host-handler
handler := newCorsHandler(srv, cors)
handler = newVHostHandler(vhosts, handler)
// Make sure timeout values are meaningful
if timeouts.ReadTimeout < time.Second {
log.Warn("Sanitizing invalid HTTP read timeout", "provided", timeouts.ReadTimeout, "updated", DefaultHTTPTimeouts.ReadTimeout)
timeouts.ReadTimeout = DefaultHTTPTimeouts.ReadTimeout
}
if timeouts.WriteTimeout < time.Second {
log.Warn("Sanitizing invalid HTTP write timeout", "provided", timeouts.WriteTimeout, "updated", DefaultHTTPTimeouts.WriteTimeout)
timeouts.WriteTimeout = DefaultHTTPTimeouts.WriteTimeout
}
if timeouts.IdleTimeout < time.Second {
log.Warn("Sanitizing invalid HTTP idle timeout", "provided", timeouts.IdleTimeout, "updated", DefaultHTTPTimeouts.IdleTimeout)
timeouts.IdleTimeout = DefaultHTTPTimeouts.IdleTimeout
}
// Bundle and start the HTTP server
return &http.Server{
Handler: handler,
ReadTimeout: timeouts.ReadTimeout,
WriteTimeout: timeouts.WriteTimeout,
IdleTimeout: timeouts.IdleTimeout,
}
}
// ServeHTTP serves JSON-RPC requests over HTTP.
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// Permit dumb empty requests for remote health-checks (AWS)
if r.Method == http.MethodGet && r.ContentLength == 0 && r.URL.RawQuery == "" {
return
}
if code, err := validateRequest(r); err != nil {
http.Error(w, err.Error(), code)
return
}
// All checks passed, create a codec that reads direct from the request body
// untilEOF and writes the response to w and order the server to process a
// single request.
ctx := r.Context()
ctx = context.WithValue(ctx, "remote", r.RemoteAddr)
ctx = context.WithValue(ctx, "scheme", r.Proto)
ctx = context.WithValue(ctx, "local", r.Host)
if ua := r.Header.Get("User-Agent"); ua != "" {
ctx = context.WithValue(ctx, "User-Agent", ua)
}
if origin := r.Header.Get("Origin"); origin != "" {
ctx = context.WithValue(ctx, "Origin", origin)
}
w.Header().Set("content-type", contentType)
codec := newHTTPServerConn(r, w)
defer codec.Close()
s.serveSingleRequest(ctx, codec)
}
// validateRequest returns a non-zero response code and error message if the
// request is invalid.
func validateRequest(r *http.Request) (int, error) {
if r.Method == http.MethodPut || r.Method == http.MethodDelete {
return http.StatusMethodNotAllowed, errors.New("method not allowed")
}
if r.ContentLength > maxRequestContentLength {
err := fmt.Errorf("content length too large (%d>%d)", r.ContentLength, maxRequestContentLength)
return http.StatusRequestEntityTooLarge, err
}
// Allow OPTIONS (regardless of content-type)
if r.Method == http.MethodOptions {
return 0, nil
}
// Check content-type
if mt, _, err := mime.ParseMediaType(r.Header.Get("content-type")); err == nil {
for _, accepted := range acceptedContentTypes {
if accepted == mt {
return 0, nil
}
}
}
// Invalid content-type
err := fmt.Errorf("invalid content type, only %s is supported", contentType)
return http.StatusUnsupportedMediaType, err
}
func newCorsHandler(srv http.Handler, allowedOrigins []string) http.Handler {
// disable CORS support if user has not specified a custom CORS configuration
if len(allowedOrigins) == 0 {
return srv
}
c := cors.New(cors.Options{
AllowedOrigins: allowedOrigins,
AllowedMethods: []string{http.MethodPost, http.MethodGet},
MaxAge: 600,
AllowedHeaders: []string{"*"},
})
return c.Handler(srv)
}
// virtualHostHandler is a handler which validates the Host-header of incoming requests.
// The virtualHostHandler can prevent DNS rebinding attacks, which do not utilize CORS-headers,
// since they do in-domain requests against the RPC api. Instead, we can see on the Host-header
// which domain was used, and validate that against a whitelist.
type virtualHostHandler struct {
vhosts map[string]struct{}
next http.Handler
}
// ServeHTTP serves JSON-RPC requests over HTTP, implements http.Handler
func (h *virtualHostHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
// if r.Host is not set, we can continue serving since a browser would set the Host header
if r.Host == "" {
h.next.ServeHTTP(w, r)
return
}
host, _, err := net.SplitHostPort(r.Host)
if err != nil {
// Either invalid (too many colons) or no port specified
host = r.Host
}
if ipAddr := net.ParseIP(host); ipAddr != nil {
// It's an IP address, we can serve that
h.next.ServeHTTP(w, r)
return
}
// Not an ip address, but a hostname. Need to validate
if _, exist := h.vhosts["*"]; exist {
h.next.ServeHTTP(w, r)
return
}
if _, exist := h.vhosts[host]; exist {
h.next.ServeHTTP(w, r)
return
}
http.Error(w, "invalid host specified", http.StatusForbidden)
}
func newVHostHandler(vhosts []string, next http.Handler) http.Handler {
vhostMap := make(map[string]struct{})
for _, allowedHost := range vhosts {
vhostMap[strings.ToLower(allowedHost)] = struct{}{}
}
return &virtualHostHandler{vhostMap, next}
}
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