path: root/rpc/http.go

// 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 (
    "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"
)

const (
    httpReadDeadLine = 60 * time.Second // wait max httpReadDeadeline for next request
)

// 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
    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) (*httpClient, 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)
}