aboutsummaryrefslogtreecommitdiffstats
path: root/rpc/http.go
blob: a26559b1221fdd702854a507d7990961a73d33f1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
// 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"
    "sync"
    "time"

    "github.com/rs/cors"
)

const (
    contentType                 = "application/json"
    maxHTTPRequestContentLength = 1024 * 128
)

var nullAddr, _ = net.ResolveTCPAddr("tcp", "127.0.0.1:0")

type httpConn struct {
    client    *http.Client
    req       *http.Request
    closeOnce sync.Once
    closed    chan struct{}
}

// httpConn is treated specially by Client.
func (hc *httpConn) LocalAddr() net.Addr              { return nullAddr }
func (hc *httpConn) RemoteAddr() net.Addr             { return nullAddr }
func (hc *httpConn) SetReadDeadline(time.Time) error  { return nil }
func (hc *httpConn) SetWriteDeadline(time.Time) error { return nil }
func (hc *httpConn) SetDeadline(time.Time) error      { return nil }
func (hc *httpConn) Write([]byte) (int, error)        { panic("Write called") }

func (hc *httpConn) Read(b []byte) (int, error) {
    <-hc.closed
    return 0, io.EOF
}

func (hc *httpConn) Close() error {
    hc.closeOnce.Do(func() { close(hc.closed) })
    return nil
}

// DialHTTP creates a new RPC clients that connection to an RPC server over HTTP.
func DialHTTP(endpoint string) (*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) (net.Conn, error) {
        return &httpConn{client: new(http.Client), req: req, closed: make(chan struct{})}, nil
    })
}

func (c *Client) sendHTTP(ctx context.Context, op *requestOp, msg interface{}) error {
    hc := c.writeConn.(*httpConn)
    respBody, err := hc.doRequest(ctx, msg)
    if err != nil {
        return err
    }
    defer respBody.Close()
    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
    }
    return resp.Body, nil
}

// 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
}

// NewHTTPServer creates a new HTTP RPC server around an API provider.
//
// Deprecated: Server implements http.Handler
func NewHTTPServer(cors []string, srv *Server) *http.Server {
    return &http.Server{Handler: newCorsHandler(srv, cors)}
}

// ServeHTTP serves JSON-RPC requests over HTTP.
func (srv *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.
    codec := NewJSONCodec(&httpReadWriteNopCloser{r.Body, w})
    defer codec.Close()

    w.Header().Set("content-type", contentType)
    srv.ServeSingleRequest(codec, OptionMethodInvocation)
}

// 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 > maxHTTPRequestContentLength {
        err := fmt.Errorf("content length too large (%d>%d)", r.ContentLength, maxHTTPRequestContentLength)
        return http.StatusRequestEntityTooLarge, err
    }
    mt, _, err := mime.ParseMediaType(r.Header.Get("content-type"))
    if err != nil || mt != contentType {
        err := fmt.Errorf("invalid content type, only %s is supported", contentType)
        return http.StatusUnsupportedMediaType, err
    }
    return 0, nil
}

func newCorsHandler(srv *Server, 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)
}