path: root/cmd/utils/client.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 utils

import (
    "encoding/json"
    "fmt"

    "strings"

    "github.com/codegangsta/cli"
    "github.com/ethereum/go-ethereum/eth"
    "github.com/ethereum/go-ethereum/logger"
    "github.com/ethereum/go-ethereum/logger/glog"
    "github.com/ethereum/go-ethereum/node"
    "github.com/ethereum/go-ethereum/rpc"
)

// NewInProcRPCClient will start a new RPC server for the given node and returns a client to interact with it.
func NewInProcRPCClient(stack *node.Node) *inProcClient {
    server := rpc.NewServer()

    offered := stack.APIs()
    for _, api := range offered {
        server.RegisterName(api.Namespace, api.Service)
    }

    web3 := node.NewPublicWeb3API(stack)
    server.RegisterName("web3", web3)

    var ethereum *eth.Ethereum
    if err := stack.Service(&ethereum); err == nil {
        net := eth.NewPublicNetAPI(stack.Server(), ethereum.NetVersion())
        server.RegisterName("net", net)
    } else {
        glog.V(logger.Warn).Infof("%v\n", err)
    }

    buf := &buf{
        requests:  make(chan []byte),
        responses: make(chan []byte),
    }
    client := &inProcClient{
        server: server,
        buf:    buf,
    }

    go func() {
        server.ServeCodec(rpc.NewJSONCodec(client.buf))
    }()

    return client
}

// buf represents the connection between the RPC server and console
type buf struct {
    readBuf   []byte      // store remaining request bytes after a partial read
    requests  chan []byte // list with raw serialized requests
    responses chan []byte // list with raw serialized responses
}

// will read the next request in json format
func (b *buf) Read(p []byte) (int, error) {
    // last read didn't read entire request, return remaining bytes
    if len(b.readBuf) > 0 {
        n := copy(p, b.readBuf)
        if n < len(b.readBuf) {
            b.readBuf = b.readBuf[:n]
        } else {
            b.readBuf = b.readBuf[:0]
        }
        return n, nil
    }

    // read next request
    req := <-b.requests
    n := copy(p, req)
    if n < len(req) {
        // buf too small, store remaining chunk for next read
        b.readBuf = req[n:]
    }

    return n, nil
}

// Write send the given buffer to the backend
func (b *buf) Write(p []byte) (n int, err error) {
    b.responses <- p
    return len(p), nil
}

// Close cleans up obtained resources.
func (b *buf) Close() error {
    close(b.requests)
    close(b.responses)

    return nil
}

// inProcClient starts a RPC server and uses buf to communicate with it.
type inProcClient struct {
    server *rpc.Server
    buf    *buf
}

// Close will stop the RPC server
func (c *inProcClient) Close() {
    c.server.Stop()
}

// Send a msg to the endpoint
func (c *inProcClient) Send(msg interface{}) error {
    d, err := json.Marshal(msg)
    if err != nil {
        return err
    }
    c.buf.requests <- d
    return nil
}

// Recv reads a message and tries to parse it into the given msg
func (c *inProcClient) Recv(msg interface{}) error {
    data := <-c.buf.responses
    return json.Unmarshal(data, &msg)
}

// Returns the collection of modules the RPC server offers.
func (c *inProcClient) SupportedModules() (map[string]string, error) {
    return rpc.SupportedModules(c)
}

// NewRemoteRPCClient returns a RPC client which connects to a running geth instance.
// Depending on the given context this can either be a IPC or a HTTP client.
func NewRemoteRPCClient(ctx *cli.Context) (rpc.Client, error) {
    if ctx.Args().Present() {
        endpoint := ctx.Args().First()
        return NewRemoteRPCClientFromString(endpoint)
    }
    // use IPC by default
    return rpc.NewIPCClient(node.DefaultIpcEndpoint())
}

// NewRemoteRPCClientFromString returns a RPC client which connects to the given
// endpoint. It must start with either `ipc:` or `rpc:` (HTTP).
func NewRemoteRPCClientFromString(endpoint string) (rpc.Client, error) {
    if strings.HasPrefix(endpoint, "ipc:") {
        return rpc.NewIPCClient(endpoint[4:])
    }
    if strings.HasPrefix(endpoint, "rpc:") {
        return rpc.NewHTTPClient(endpoint[4:])
    }
    if strings.HasPrefix(endpoint, "http://") {
        return rpc.NewHTTPClient(endpoint)
    }
    if strings.HasPrefix(endpoint, "ws:") {
        return rpc.NewWSClient(endpoint)
    }

    return nil, fmt.Errorf("invalid endpoint")
}