path: root/simulation/tcp-network.go

// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core 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 dexon-consensus-core 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 dexon-consensus-core library. If not, see
// <http://www.gnu.org/licenses/>.

package simulation

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "math/rand"
    "net/http"
    "runtime"
    "strings"
    "sync"
    "time"

    "github.com/dexon-foundation/dexon-consensus-core/core"
    "github.com/dexon-foundation/dexon-consensus-core/core/types"
)

// TCPNetwork implements the core.Network interface.
type TCPNetwork struct {
    local    bool
    port     int
    endpoint core.Endpoint

    peerServer    string
    endpointMutex sync.RWMutex
    endpoints     map[types.ValidatorID]string
    recieveChan   chan interface{}
}

// NewTCPNetwork returns pointer to a new Network instance.
func NewTCPNetwork(local bool, peerServer string) *TCPNetwork {
    port := 1024 + rand.Int()%1024
    if !local {
        port = peerPort
    }
    return &TCPNetwork{
        local:       local,
        peerServer:  peerServer,
        port:        port,
        endpoints:   make(map[types.ValidatorID]string),
        recieveChan: make(chan interface{}, msgBufferSize),
    }
}

// Start starts the http server for accepting message.
func (n *TCPNetwork) Start() {
    addr := fmt.Sprintf("0.0.0.0:%d", n.port)
    server := &http.Server{
        Addr:    addr,
        Handler: n,
    }
    fmt.Printf("Validator started at %s\n", addr)
    server.ListenAndServe()
}

// NumPeers returns the number of peers in the network.
func (n *TCPNetwork) NumPeers() int {
    n.endpointMutex.Lock()
    defer n.endpointMutex.Unlock()

    return len(n.endpoints)
}

// ServerHTTP implements the http.Handler interface.
func (n *TCPNetwork) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    defer r.Body.Close()
    body, err := ioutil.ReadAll(r.Body)
    if err != nil {
        w.WriteHeader(http.StatusBadRequest)
        return
    }

    m := struct {
        Type    string          `json:"type"`
        Payload json.RawMessage `json:"payload"`
    }{}
    if err := json.Unmarshal(body, &m); err != nil {
        w.WriteHeader(http.StatusBadRequest)
        return
    }

    switch m.Type {
    case "block":
        block := &types.Block{}
        if err := json.Unmarshal(m.Payload, block); err != nil {
            w.WriteHeader(http.StatusBadRequest)
            return
        }
        n.recieveChan <- block
    default:
        w.WriteHeader(http.StatusBadRequest)
        return
    }
}

// Join allow a client to join the network. It reutnrs a interface{} channel for
// the client to recieve information.
func (n *TCPNetwork) Join(endpoint core.Endpoint) chan interface{} {
    n.endpointMutex.Lock()
    defer n.endpointMutex.Unlock()

    n.endpoint = endpoint

    joinURL := fmt.Sprintf("http://%s:%d/join", n.peerServer, peerPort)
    peersURL := fmt.Sprintf("http://%s:%d/peers", n.peerServer, peerPort)

    client := &http.Client{Timeout: 5 * time.Second}

    // Join the peer list.
    for {
        time.Sleep(time.Second)

        req, err := http.NewRequest(http.MethodGet, joinURL, nil)
        if err != nil {
            continue
        }
        req.Header.Add("ID", endpoint.GetID().String())
        req.Header.Add("PORT", fmt.Sprintf("%d", n.port))

        resp, err := client.Do(req)
        if err == nil && resp.StatusCode == http.StatusOK {
            break
        }
    }

    var peerList map[types.ValidatorID]string

    // Wait for the server to collect all validators and return a list.
    for {
        time.Sleep(time.Second)

        req, err := http.NewRequest(http.MethodGet, peersURL, nil)
        if err != nil {
            fmt.Println(err)
            continue
        }
        req.Header.Add("ID", endpoint.GetID().String())

        resp, err := client.Do(req)
        if err != nil || resp.StatusCode != http.StatusOK {
            continue
        }

        defer resp.Body.Close()
        body, err := ioutil.ReadAll(resp.Body)

        if err := json.Unmarshal(body, &peerList); err != nil {
            fmt.Printf("error: %v", err)
            continue
        }
        break
    }

    for key, val := range peerList {
        n.endpoints[key] = val
    }
    return n.recieveChan
}

// Send sends a msg to another client.
func (n *TCPNetwork) Send(destID types.ValidatorID, msg interface{}) {
    clientAddr, exists := n.endpoints[destID]
    if !exists {
        return
    }

    message := struct {
        Type    string      `json:"type"`
        Payload interface{} `json:"payload"`
    }{}

    switch v := msg.(type) {
    case *types.Block:
        message.Type = "block"
        message.Payload = v
    default:
        fmt.Println("error: invalid message type")
        return
    }

    messageJSON, err := json.Marshal(message)
    if err != nil {
        fmt.Printf("error: failed to marshal json: %v\n%+v\n", err, message)
        return
    }

    msgURL := fmt.Sprintf("http://%s/msg", clientAddr)

    go func() {
        retries := 3
        client := &http.Client{Timeout: 5 * time.Second}

        for i := 0; i < retries; i++ {
            req, err := http.NewRequest(
                http.MethodPost, msgURL, strings.NewReader(string(messageJSON)))
            if err != nil {
                continue
            }
            req.Header.Add("ID", n.endpoint.GetID().String())

            resp, err := client.Do(req)
            if err == nil && resp.StatusCode == http.StatusOK {
                runtime.Goexit()
            }
            time.Sleep(1 * time.Second)
        }
        fmt.Printf("failed to send message: %v\n", msg)
    }()
}

// BroadcastBlock broadcast blocks into the network.
func (n *TCPNetwork) BroadcastBlock(block *types.Block) {
    for endpoint := range n.endpoints {
        n.Send(endpoint, block.Clone())
    }
}