roughtime.googlesource.com/roughtime.git@v0.0.0-20201210012726-dd529367052d/go/server/server.go (about)

     1  // Copyright 2016 The Roughtime Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //   http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License. */
    14  
    15  // server is a very basic Roughtime server.
    16  //
    17  // First, run with the flag -generate-key. This will print out a private key
    18  // and a JSON template for the server. Put the private key (as hex) in a file
    19  // named "priv" and then run with no arguments.
    20  package main
    21  
    22  // TODO(agl): add a test once the client functionality has landed.
    23  
    24  import (
    25  	"bytes"
    26  	"crypto/rand"
    27  	"encoding/hex"
    28  	"encoding/json"
    29  	"errors"
    30  	"flag"
    31  	"fmt"
    32  	"io/ioutil"
    33  	"log"
    34  	"net"
    35  	"os"
    36  	"time"
    37  
    38  	"golang.org/x/crypto/ed25519"
    39  	"roughtime.googlesource.com/go/config"
    40  	"roughtime.googlesource.com/go/protocol"
    41  )
    42  
    43  var (
    44  	genKey         = flag.Bool("generate-key", false, "Generate a new key pair")
    45  	privateKeyFile = flag.String("private-key", "priv", "Filename of the private key (hex encoded)")
    46  	port           = flag.Int("port", 5333, "Port number to listen on")
    47  )
    48  
    49  func main() {
    50  	flag.Parse()
    51  
    52  	var err error
    53  	if *genKey {
    54  		err = generateKeyPair()
    55  	} else {
    56  		err = serveForever()
    57  	}
    58  
    59  	if err != nil {
    60  		fmt.Fprintf(os.Stderr, "%s\n", err)
    61  		os.Exit(1)
    62  	}
    63  }
    64  
    65  func serveForever() error {
    66  	privateKeyHex, err := ioutil.ReadFile(*privateKeyFile)
    67  	if err != nil {
    68  		return errors.New("Cannot open private key: " + err.Error())
    69  	}
    70  
    71  	privateKey, err := hex.DecodeString(string(bytes.TrimSpace(privateKeyHex)))
    72  	if err != nil {
    73  		return errors.New("Cannot parse private key: " + err.Error())
    74  	}
    75  
    76  	conn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4(0, 0, 0, 0), Port: *port})
    77  	if err != nil {
    78  		return errors.New("Cannot listen on port: " + err.Error())
    79  	}
    80  
    81  	onlinePublicKey, onlinePrivateKey, err := ed25519.GenerateKey(rand.Reader)
    82  	if err != nil {
    83  		return errors.New("Cannot generate private key: " + err.Error())
    84  	}
    85  
    86  	// As this is just an example, the certificate is created covering the
    87  	// maximum possible range.
    88  	cert, err := protocol.CreateCertificate(0, ^uint64(0), onlinePublicKey, privateKey)
    89  	if err != nil {
    90  		return errors.New("Cannot generate certificate: " + err.Error())
    91  	}
    92  
    93  	log.Printf("Processing requests on port %d", *port)
    94  
    95  	var packetBuf [protocol.MinRequestSize]byte
    96  
    97  	for {
    98  		n, sourceAddr, err := conn.ReadFromUDP(packetBuf[:])
    99  		if err != nil {
   100  			log.Print(err)
   101  		}
   102  
   103  		if n < protocol.MinRequestSize {
   104  			continue
   105  		}
   106  
   107  		packet, err := protocol.Decode(packetBuf[:n])
   108  		if err != nil {
   109  			continue
   110  		}
   111  
   112  		nonce, ok := packet[protocol.TagNonce]
   113  		if !ok || len(nonce) != protocol.NonceSize {
   114  			continue
   115  		}
   116  
   117  		midpoint := uint64(time.Now().UnixNano() / 1000)
   118  		radius := uint32(1000000)
   119  
   120  		replies, err := protocol.CreateReplies([][]byte{nonce}, midpoint, radius, cert, onlinePrivateKey)
   121  		if err != nil {
   122  			log.Print(err)
   123  			continue
   124  		}
   125  
   126  		if len(replies) != 1 {
   127  			continue
   128  		}
   129  
   130  		conn.WriteToUDP(replies[0], sourceAddr)
   131  	}
   132  }
   133  
   134  func generateKeyPair() error {
   135  	rootPublic, rootPrivate, err := ed25519.GenerateKey(rand.Reader)
   136  	if err != nil {
   137  		return err
   138  	}
   139  
   140  	fmt.Printf("Private key: %x\n\n", rootPrivate)
   141  
   142  	exampleConfig := config.ServersJSON{
   143  		Servers: []config.Server{
   144  			config.Server{
   145  				Name:          "FIXME",
   146  				PublicKeyType: "ed25519",
   147  				PublicKey:     rootPublic,
   148  				Addresses: []config.ServerAddress{
   149  					config.ServerAddress{
   150  						Protocol: "udp",
   151  						Address:  "FIXME",
   152  					},
   153  				},
   154  			},
   155  		},
   156  	}
   157  
   158  	jsonBytes, err := json.MarshalIndent(exampleConfig, "", "  ")
   159  	if err != nil {
   160  		return err
   161  	}
   162  
   163  	os.Stdout.Write(jsonBytes)
   164  	os.Stdout.WriteString("\n")
   165  
   166  	return nil
   167  }