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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"
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"net/url"
"strings"
"io"
"github.com/rs/cors"
)
const (
maxHTTPRequestContentLength = 1024 * 128
)
// httpClient connects to a geth RPC server over HTTP.
type httpClient struct {
endpoint *url.URL // HTTP-RPC server endpoint
lastRes []byte // HTTP requests are synchronous, store last response
}
// NewHTTPClient create a new RPC clients that connection to a geth RPC server
// over HTTP.
func NewHTTPClient(endpoint string) (Client, error) {
url, err := url.Parse(endpoint)
if err != nil {
return nil, err
}
return &httpClient{endpoint: url}, nil
}
// Send will serialize the given msg to JSON and sends it to the RPC server.
// Since HTTP is synchronous the response is stored until Recv is called.
func (client *httpClient) Send(msg interface{}) error {
var body []byte
var err error
client.lastRes = nil
if body, err = json.Marshal(msg); err != nil {
return err
}
httpReq, err := http.NewRequest("POST", client.endpoint.String(), bytes.NewBuffer(body))
if err != nil {
return err
}
httpReq.Header.Set("Content-Type", "application/json")
httpClient := http.Client{}
resp, err := httpClient.Do(httpReq)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode == http.StatusOK {
client.lastRes, err = ioutil.ReadAll(resp.Body)
return err
}
return fmt.Errorf("unable to handle request")
}
// Recv will try to deserialize the last received response into the given msg.
func (client *httpClient) Recv(msg interface{}) error {
return json.Unmarshal(client.lastRes, &msg)
}
// Close is not necessary for httpClient
func (client *httpClient) Close() {
}
// SupportedModules will return the collection of offered RPC modules.
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,
}
}
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