├── .gitignore ├── LICENSE ├── README.md ├── auth.go ├── auth_test.go ├── wherez.go ├── wherez └── wherez.go └── wherez_test.go /.gitignore: -------------------------------------------------------------------------------- 1 | wherez/wherez 2 | wherez/wherez.exe 3 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright {yyyy} {name of copyright owner} 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | 203 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | Wherez 2 | ====== 3 | 4 | ![Presentation](https://lh4.googleusercontent.com/-ugw0s4ql6uE/UsCLlgoSdSI/AAAAAAABFw0/ct0yB6ufE_c/w384-h216-no/output_4hMaVU.gif) 5 | 6 | Wherez (Where Zee) is a p2p program and library that lets you register 7 | and discover sibling servers in the network based on a shared 8 | passphrase. It uses the Mainline DHT network to advertise its own 9 | existence and to look for other nodes that are running with the same 10 | passphrase. 11 | 12 | It authenticates sibling peers using an HMAC-based mechanism. 13 | 14 | Example applications: 15 | 16 | - find the location of your company's doozerd, Chubby or DNS servers. 17 | - robust way for stolen notebooks to "phone home". 18 | - register and locate servers in a corporate network based on 19 | function, by using different passphrases for the DNS server, LDAP 20 | server, etc. 21 | 22 | This software is in early stages of development. 23 | 24 | This repository contains a library and a command-line tool. 25 | 26 | Example CLI usage: 27 | 28 | $ cd wherez ; go build 29 | $ ./wherez 8080 "wherezexample" 30 | peer found: 14.15.87.13:3111 31 | peer found: 77.66.77.22:3211 32 | peer found: 16.97.12.12:3312 33 | 34 | 8080 is your application's port to be advertised to other wherez nodes. 35 | 36 | The IP:port pairs that appear are those peers provided by Wherez nodes that have been contacted and authenticated. 37 | 38 | Recently started wherez nodes may take several minutes to find other peers and to be found by them. 39 | 40 | How does it work? 41 | ------------------ 42 | 43 | Presentation: http://goo.gl/vn7Pvh 44 | -------------------------------------------------------------------------------- /auth.go: -------------------------------------------------------------------------------- 1 | package wherez 2 | 3 | import ( 4 | "bytes" 5 | "crypto/hmac" 6 | "crypto/rand" 7 | "crypto/sha256" 8 | "encoding/binary" 9 | "fmt" 10 | "io" 11 | "log" 12 | "net" 13 | ) 14 | 15 | var ( 16 | // Identifies wherez TCP messages. 17 | magicHeader = []byte("wherez") 18 | // dedupe is needed to ignore connections from self. 19 | dedupe []byte 20 | // If true, connections to self are allowed - used for testing. 21 | allowSelfConnection = false 22 | ) 23 | 24 | const ( 25 | messageLen = 20 26 | dedupeLen = 10 27 | ) 28 | 29 | func init() { 30 | var err error 31 | dedupe, err = randMsg() 32 | if err != nil { 33 | log.Fatalln("could not generate a dedupe id:", err) 34 | } 35 | dedupe = dedupe[0:dedupeLen] 36 | } 37 | 38 | // Connect on that peer's TCP port and authenticate. Alice starts a 39 | // conversation with Bob. 40 | // 41 | // A: Provides a challenge. 42 | // B: Provides a response, authenticated with the shared secret. 43 | // 44 | // A: Requests port number information. 45 | // B: Provides the application port number. 46 | // 47 | // Result: Alice now knows that bob:portX is a valid member of the connection pool. 48 | // 49 | // In the real world, the above is done in only one message each way. Protocol: 50 | // - sends initial messsage of 36 bytes, containing: 51 | // ~ magicHeader with "wherez" ASCII encoded. 52 | // ~ 10 byte dedupe ID, which the remote node uses to identify 53 | // connection to self. 54 | // ~ 20 bytes challenge. 55 | // - the other endpoint sends a 20 bytes message containing 2 bytes 56 | // relative to the application port, plus 32 bytes of message MAC, calculated from 57 | // the 20 bytes of client challenge. 58 | // The MAC should be generated using the shared passphrase. 59 | 60 | type Challenge struct { 61 | MagicHeader [6]byte 62 | Dedupe [10]byte 63 | Challenge [20]byte 64 | } 65 | 66 | func newChallenge() (m Challenge, err error) { 67 | //m = Challenge{} 68 | copy(m.MagicHeader[:], magicHeader[:]) 69 | copy(m.Dedupe[:], dedupe[:]) 70 | challenge, err := randMsg() 71 | if err != nil { 72 | return 73 | } 74 | copy(m.Challenge[:], challenge[:]) 75 | return 76 | } 77 | 78 | func checkPeer(addr string, passphrase []byte, c chan Peer) { 79 | if peer, err := verifyPeer(addr, passphrase); err == nil { 80 | c <- peer 81 | } 82 | 83 | } 84 | 85 | // verifyPeer connects to a host:port address specified in peer and sends it a 86 | // cryptographic challenge. If the peer responds with a valid MAC that appears 87 | // to have been generated with the shared secret in passphrase, consider it a 88 | // valid Peer and returns the details. If the connection fails or the peer 89 | // authentication fails, returns an error. 90 | func verifyPeer(peer string, passphrase []byte) (p Peer, err error) { 91 | conn, err := net.Dial("tcp", peer) 92 | if err != nil { 93 | return 94 | } 95 | defer conn.Close() 96 | var challenge Challenge 97 | challenge, err = newChallenge() 98 | if err != nil { 99 | // log.Printf("auth newChallenge error %v", err) 100 | return 101 | } 102 | if err = binary.Write(conn, binary.LittleEndian, challenge); err != nil { 103 | // The other side is either unreachable or we connected to 104 | // ourselves and closed the connection. 105 | return 106 | } 107 | in := new(Response) 108 | if err = binary.Read(conn, binary.LittleEndian, in); err != nil { 109 | // log.Println("auth could not read response from conn:", err) 110 | return 111 | } 112 | if !checkMAC(challenge.Challenge[:], in.MAC[:], passphrase) { 113 | return p, fmt.Errorf("Invalid challenge response") 114 | } 115 | host, _, err := net.SplitHostPort(peer) 116 | if err != nil { 117 | return 118 | } 119 | return Peer{Addr: fmt.Sprintf("%v:%v", host, in.Port)}, nil 120 | } 121 | 122 | func randMsg() ([]byte, error) { 123 | b := make([]byte, 20) 124 | _, err := rand.Read(b) 125 | return b, err 126 | } 127 | 128 | func listenAuth(port, appPort int, passphrase []byte) (net.Addr, error) { 129 | ln, err := net.ListenTCP("tcp", &net.TCPAddr{Port: port}) 130 | if err != nil { 131 | return nil, err 132 | } 133 | go func() { 134 | for { 135 | conn, err := ln.Accept() 136 | if err != nil { 137 | log.Println("listenAuth accept error. Stopping listener.", err) 138 | return 139 | } 140 | go handleConn(conn, appPort, passphrase) 141 | } 142 | }() 143 | return ln.Addr(), nil 144 | } 145 | 146 | // Response containing proof that the server (Bob) knows the shared secret and 147 | // the application port information required by the client. 148 | type Response struct { 149 | Port uint16 150 | // MAC of the Challenge sent by the client (Alice). 151 | MAC [32]byte 152 | } 153 | 154 | func handleConn(conn io.ReadWriteCloser, appPort int, passphrase []byte) { 155 | // Everything is done with one packet in and one packet out, so close 156 | // the connection after this function ends. 157 | defer conn.Close() 158 | 159 | // Parse the incoming packet. 160 | in := new(Challenge) 161 | err := binary.Read(conn, binary.LittleEndian, in) 162 | if err != nil { 163 | return 164 | } 165 | // Verify if the magic header is correct. Several DHT nodes will connect 166 | // to whatever peer they believe exist, most likely to scrape their 167 | // content. But we're not BitTorrent clients, so we just close the 168 | // connection. This shouldn't cause damage to the network because we're 169 | // not pretending to be peers for a bittorrent infohash. So these 170 | // spurious incoming connections are from misbehaving clients. 171 | if !bytes.Equal(in.MagicHeader[:], magicHeader) { 172 | // Not a wherez peer. 173 | return 174 | } 175 | // dedupe is a small byte array generated on initialization that 176 | // identifies this server. If the incoming request has the same dedupe ID, 177 | // it means it's trying to connect to itself. That's a normal thing, but 178 | // obviously useless, so close the connection. 179 | // To blacklist the address on the client side, the protocol would have 180 | // to have another step for the error feedback and for now that doesn't 181 | // seem worth it. 182 | if !allowSelfConnection && bytes.Equal(in.Dedupe[:], dedupe) { 183 | // Connection to self. Closing. 184 | return 185 | } 186 | // Calculate the challenge response. 187 | mac := hmac.New(sha256.New, passphrase) 188 | mac.Write(in.Challenge[:]) 189 | 190 | // Create the response packet. 191 | response := Response{Port: uint16(appPort)} 192 | copy(response.MAC[:], mac.Sum(nil)) 193 | 194 | if err = binary.Write(conn, binary.LittleEndian, response); err != nil { 195 | // log.Println("handleConn failed to write to remote peer:", err) 196 | return 197 | } 198 | } 199 | 200 | func checkMAC(message, messageMAC, key []byte) bool { 201 | mac := hmac.New(sha256.New, key) 202 | mac.Write(message) 203 | expectedMAC := mac.Sum(nil) 204 | return hmac.Equal(messageMAC, expectedMAC) 205 | } 206 | -------------------------------------------------------------------------------- /auth_test.go: -------------------------------------------------------------------------------- 1 | package wherez 2 | 3 | import ( 4 | "bytes" 5 | "net" 6 | "testing" 7 | ) 8 | 9 | type rwc struct { 10 | bytes.Buffer 11 | } 12 | 13 | func (w *rwc) Close() error { 14 | return nil 15 | } 16 | 17 | // addrLocal takes the port information from a net.Addr response and creates a 18 | // "localhost:port" string. 19 | func addrLocal(addr net.Addr) string { 20 | _, port, _ := net.SplitHostPort(addr.String()) 21 | return net.JoinHostPort("localhost", port) 22 | } 23 | 24 | func TestAuth(t *testing.T) { 25 | // Ignore the dedupe ID check. 26 | allowSelfConnection = true 27 | passphrase := []byte("secret") 28 | want := "localhost:3000" 29 | 30 | // Starts server in the background. 31 | addr, err := listenAuth(0, 3000, passphrase) 32 | if err != nil { 33 | t.Fatalf("listenAuth error %v", err) 34 | } 35 | 36 | // Client. 37 | peer, err := verifyPeer(addrLocal(addr), passphrase) 38 | if err != nil { 39 | t.Errorf("auth: %v", err) 40 | } 41 | if peer.String() != want { 42 | t.Errorf("Wanted peer %v, got %v", want, peer.String()) 43 | } 44 | allowSelfConnection = false 45 | } 46 | 47 | func TestBrokenAuth(t *testing.T) { 48 | // Ignore the dedupe ID check. 49 | allowSelfConnection = true 50 | passphrase := []byte("secrettwo") 51 | 52 | // Starts server in the background. 53 | addr, err := listenAuth(0, 3000, passphrase) 54 | if err != nil { 55 | t.Fatalf("listenAuth error %v", err) 56 | } 57 | 58 | // Connect to the server and tries to verify it. 59 | if _, err := verifyPeer(addrLocal(addr), []byte("someotherpass")); err == nil { 60 | t.Fatalf("Expected an error for failed auth, got nil") 61 | } 62 | allowSelfConnection = false 63 | } 64 | -------------------------------------------------------------------------------- /wherez.go: -------------------------------------------------------------------------------- 1 | // wherez (Where Zee) lets you register and discover sibling nodes in the network 2 | // based on a shared passphrase. It uses the Mainline DHT network to advertise 3 | // its own existence and to look for other nodes that are running with the same 4 | // passphrase. 5 | // 6 | // Wherez authenticates sibling peers using an HMAC-based mechanism. 7 | // 8 | // Example applications: 9 | // - find the location of your company's doozerd, Chubby or DNS servers. 10 | // - robust way for stolen notebooks to "phone home". 11 | // - register and locate servers in a corporate network based on function, by 12 | // using different passphrases for the DNS server, LDAP server, etc. 13 | // 14 | // This software is in early stages of development. 15 | package wherez 16 | 17 | import ( 18 | "crypto/sha1" 19 | "crypto/sha256" 20 | "fmt" 21 | "log" 22 | "time" 23 | 24 | "github.com/nictuku/dht" 25 | ) 26 | 27 | // FindAuthenticatedPeers uses the BitTorrent DHT network to find sibling 28 | // Wherez nodes that are using the same passphrase. Wherez will listen on the 29 | // specified port for both TCP and UDP protocols. The port must be accessible 30 | // from the public Internet (UPnP is not supported yet). 31 | // 32 | // Wherez will try aggressively to find at least minPeers as fast as possible. 33 | // 34 | // The passphrase will be used to authenticate remote peers. This wherez node 35 | // will keep running indefinitely as a DHT node. 36 | // 37 | // If appPort is a positive number, wherez will advertise that our main application 38 | // is on port appPort of the current host. If it's negative, it doesn't 39 | // announce itself as a peer. 40 | func FindAuthenticatedPeers(port, appPort, minPeers int, passphrase []byte) chan Peer { 41 | c := make(chan Peer) 42 | go findAuthenticatedPeers(port, appPort, minPeers, passphrase, c) 43 | return c 44 | } 45 | 46 | type Peer struct { 47 | Addr string 48 | } 49 | 50 | func (p Peer) String() string { 51 | return fmt.Sprintf("%v", p.Addr) 52 | } 53 | 54 | func findAuthenticatedPeers(port, appPort, minPeers int, passphrase []byte, c chan Peer) { 55 | defer close(c) 56 | ih, err := infoHash(passphrase) 57 | if err != nil { 58 | log.Println("Could not calculate infohash for the provided passphrase", err) 59 | return 60 | } 61 | announce := false 62 | if appPort > 0 { 63 | announce = true 64 | if _, err = listenAuth(port, appPort, passphrase); err != nil { 65 | log.Println("Could not open listener:", err) 66 | return 67 | } 68 | } 69 | // Connect to the DHT network. 70 | d, err := dht.NewDHTNode(port, minPeers, announce) 71 | if err != nil { 72 | log.Println("Could not create the DHT node:", err) 73 | return 74 | } 75 | d.AddNode("213.239.195.138:40000") 76 | go d.DoDHT() 77 | // Sends authenticated peers to channel c. 78 | go obtainPeers(d, passphrase, c) 79 | 80 | for { 81 | // Keeps requesting for the infohash. This is a no-op if the 82 | // DHT is satisfied with the number of peers it has found. 83 | d.PeersRequest(string(ih), true) 84 | 85 | time.Sleep(5 * time.Second) 86 | } 87 | } 88 | 89 | func obtainPeers(d *dht.DHT, passphrase []byte, c chan Peer) { 90 | for r := range d.PeersRequestResults { 91 | for _, peers := range r { 92 | for _, x := range peers { 93 | // A DHT peer for our infohash was found. It 94 | // needs to be authenticated. 95 | checkPeer(dht.DecodePeerAddress(x), passphrase, c) 96 | } 97 | } 98 | } 99 | } 100 | 101 | // infohash used for this wherez lookup. This should be somewhat hard to guess 102 | // but it's not exactly a secret. 103 | func infoHash(passphrase []byte) (dht.InfoHash, error) { 104 | // SHA256 of the passphrase. 105 | h256 := sha256.New() 106 | h256.Write(passphrase) 107 | h := h256.Sum(nil) 108 | 109 | // Assuming perfect rainbow databases, it's better if the infohash does not 110 | // give out too much about the passphrase. Take half of this hash, then 111 | // generate a SHA1 hash from it. 112 | h2 := h[0 : sha256.Size/2] 113 | 114 | // Mainline DHT uses sha1. 115 | h160 := sha1.New() 116 | h160.Write(h2) 117 | h3 := h160.Sum(nil) 118 | return dht.InfoHash(h3[:]), nil 119 | } 120 | -------------------------------------------------------------------------------- /wherez/wherez.go: -------------------------------------------------------------------------------- 1 | package main 2 | 3 | import ( 4 | "flag" 5 | "fmt" 6 | "log" 7 | "strconv" 8 | 9 | "github.com/nictuku/wherez" 10 | ) 11 | 12 | // port for the wherez protocol (UDP+TCP). 13 | const port = 40000 14 | 15 | func main() { 16 | flag.Parse() 17 | if len(flag.Args()) != 2 { 18 | log.Fatalln("Usage: wherez [options] ") 19 | } 20 | appPort, err := strconv.Atoi(flag.Arg(0)) 21 | if err != nil { 22 | log.Fatalf("Invalid port parameter: %v", err) 23 | } 24 | passphrase := flag.Arg(1) 25 | c := wherez.FindAuthenticatedPeers(port, appPort, 1, []byte(passphrase)) 26 | for p := range c { 27 | // Peer found! 28 | fmt.Println("peer found:", p.String()) 29 | } 30 | } 31 | -------------------------------------------------------------------------------- /wherez_test.go: -------------------------------------------------------------------------------- 1 | package wherez 2 | 3 | import ( 4 | "fmt" 5 | "testing" 6 | ) 7 | 8 | func TestInfoHash(t *testing.T) { 9 | ih, err := infoHash([]byte("aaaaa")) 10 | if err != nil { 11 | t.Errorf("infoHash error: %v", err) 12 | } 13 | if fmt.Sprintf("%x", ih) != "97207c9437e672af8e1731f6a7200a78623886ea" { 14 | t.Errorf("Unexpected ih: %x", ih) 15 | } 16 | } 17 | 18 | func DisabledTestFindPeers(t *testing.T) { 19 | c := FindAuthenticatedPeers(60000, 31337, 1, []byte("wherezexample")) 20 | for p := range c { 21 | t.Logf("Found %v", p.String()) 22 | return 23 | } 24 | } 25 | --------------------------------------------------------------------------------