Implementation
This commit is contained in:
AudriusButkevicius
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d7c8075862
commit
78fb7fe9f9
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@ -0,0 +1,323 @@
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// Copyright (C) 2015 Audrius Butkevicius and Contributors (see the CONTRIBUTORS file).
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package main
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import (
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"crypto/tls"
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"encoding/json"
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"flag"
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"fmt"
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"io/ioutil"
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"log"
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"math/rand"
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"net"
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"net/http"
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"net/url"
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"path/filepath"
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"strings"
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"time"
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"github.com/kardianos/osext"
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"github.com/syncthing/relaysrv/client"
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"github.com/syncthing/syncthing/lib/sync"
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"github.com/syncthing/syncthing/lib/tlsutil"
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)
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type relay struct {
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URL string `json:"url"`
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}
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func (r relay) String() string {
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return r.URL
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}
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type request struct {
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relay relay
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uri *url.URL
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result chan result
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}
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type result struct {
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err error
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eviction time.Duration
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}
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var (
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binDir string
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testCert []tls.Certificate
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listen string
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dir string
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evictionTime time.Duration
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debug bool
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requests = make(chan request, 10)
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mut sync.RWMutex = sync.NewRWMutex()
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knownRelays []relay = make([]relay, 0)
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permanentRelays []relay = make([]relay, 0)
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evictionTimers map[string]*time.Timer = make(map[string]*time.Timer)
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)
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func main() {
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flag.StringVar(&listen, "listen", ":80", "Listen address")
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flag.StringVar(&dir, "keys", "", "Directory where http-cert.pem and http-key.pem is stored for TLS listening")
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flag.BoolVar(&debug, "debug", false, "Enable debug output")
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flag.DurationVar(&evictionTime, "eviction", time.Hour, "After how long the relay is evicted")
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flag.Parse()
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var listener net.Listener
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var err error
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binDir, err = osext.ExecutableFolder()
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if err != nil {
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log.Fatalln("Failed to locate executable directory")
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}
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loadPermanentRelays()
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loadOrCreateTestCertificate()
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go requestProcessor()
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if dir != "" {
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if debug {
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log.Println("Starting TLS listener")
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}
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certFile, keyFile := filepath.Join(dir, "http-cert.pem"), filepath.Join(dir, "http-key.pem")
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cert, err := tls.LoadX509KeyPair(certFile, keyFile)
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if err != nil {
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log.Fatalln("Failed to load HTTP X509 key pair:", err)
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}
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tlsCfg := &tls.Config{
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Certificates: []tls.Certificate{cert},
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MinVersion: tls.VersionTLS10, // No SSLv3
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CipherSuites: []uint16{
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// No RC4
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tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
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tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
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tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
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tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
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tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
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tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
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tls.TLS_RSA_WITH_AES_128_CBC_SHA,
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tls.TLS_RSA_WITH_AES_256_CBC_SHA,
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tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
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tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
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},
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}
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listener, err = tls.Listen("tcp", listen, tlsCfg)
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} else {
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if debug {
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log.Println("Starting plain listener")
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}
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listener, err = net.Listen("tcp", listen)
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}
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if err != nil {
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log.Fatalln("listen:", err)
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}
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handler := http.NewServeMux()
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handler.HandleFunc("/", handleRequest)
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srv := http.Server{
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Handler: handler,
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ReadTimeout: 10 * time.Second,
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}
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err = srv.Serve(listener)
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if err != nil {
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log.Fatalln("serve:", err)
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}
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}
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func handleRequest(w http.ResponseWriter, r *http.Request) {
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switch r.Method {
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case "GET":
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handleGetRequest(w, r)
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case "POST":
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handlePostRequest(w, r)
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default:
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if debug {
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log.Println("Unhandled HTTP method", r.Method)
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}
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http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
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}
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}
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func handleGetRequest(w http.ResponseWriter, r *http.Request) {
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w.Header().Set("Content-Type", "application/json; charset=utf-8")
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mut.RLock()
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relays := append(permanentRelays, knownRelays...)
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mut.RUnlock()
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// Shuffle
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for i := range relays {
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j := rand.Intn(i + 1)
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relays[i], relays[j] = relays[j], relays[i]
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}
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json.NewEncoder(w).Encode(map[string][]relay{
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"relays": relays,
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})
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}
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func handlePostRequest(w http.ResponseWriter, r *http.Request) {
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var newRelay relay
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err := json.NewDecoder(r.Body).Decode(&newRelay)
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r.Body.Close()
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if err != nil {
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if debug {
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log.Println("Failed to parse payload")
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}
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http.Error(w, err.Error(), 500)
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return
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}
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for _, current := range permanentRelays {
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if current == newRelay {
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if debug {
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log.Println("Asked to add a relay", newRelay, "which exists in permanent list")
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}
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http.Error(w, "Invalid request", 500)
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return
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}
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}
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uri, err := url.Parse(newRelay.URL)
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if err != nil {
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if debug {
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log.Println("Failed to parse URI", newRelay.URL)
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}
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http.Error(w, err.Error(), 500)
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return
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}
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reschan := make(chan result)
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select {
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case requests <- request{newRelay, uri, reschan}:
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result := <-reschan
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if result.err != nil {
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http.Error(w, result.err.Error(), 500)
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return
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}
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w.Header().Set("Content-Type", "application/json; charset=utf-8")
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json.NewEncoder(w).Encode(map[string]time.Duration{
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"evictionIn": result.eviction,
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})
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default:
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if debug {
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log.Println("Dropping request")
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}
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w.WriteHeader(429)
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}
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}
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func loadPermanentRelays() {
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path, err := osext.ExecutableFolder()
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if err != nil {
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log.Println("Failed to locate executable directory")
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return
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}
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content, err := ioutil.ReadFile(filepath.Join(path, "relays"))
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if err != nil {
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return
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}
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for _, line := range strings.Split(string(content), "\n") {
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if len(line) == 0 {
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continue
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}
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permanentRelays = append(permanentRelays, relay{
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URL: line,
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})
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if debug {
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log.Println("Adding permanent relay", line)
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}
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}
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}
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func loadOrCreateTestCertificate() {
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certFile, keyFile := filepath.Join(binDir, "cert.pem"), filepath.Join(binDir, "key.pem")
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cert, err := tls.LoadX509KeyPair(certFile, keyFile)
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if err == nil {
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testCert = []tls.Certificate{cert}
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return
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}
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cert, err = tlsutil.NewCertificate(certFile, keyFile, "relaypoolsrv", 3072)
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if err != nil {
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log.Fatalln("Failed to create test X509 key pair:", err)
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}
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testCert = []tls.Certificate{cert}
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}
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func requestProcessor() {
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for request := range requests {
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if debug {
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log.Println("Request for", request.relay)
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}
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if !client.TestRelay(request.uri, testCert, 250*time.Millisecond, 4) {
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if debug {
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log.Println("Test for relay", request.relay, "failed")
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}
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request.result <- result{fmt.Errorf("test failed"), 0}
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continue
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}
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mut.Lock()
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timer, ok := evictionTimers[request.relay.URL]
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if ok {
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if debug {
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log.Println("Stopping existing timer for", request.relay)
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}
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timer.Stop()
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}
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for _, current := range knownRelays {
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if current == request.relay {
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if debug {
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log.Println("Relay", request.relay, "already exists")
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}
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goto found
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}
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}
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if debug {
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log.Println("Adding new relay", request.relay)
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}
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knownRelays = append(knownRelays, request.relay)
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found:
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evictionTimers[request.relay.URL] = time.AfterFunc(evictionTime, evict(request.relay))
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mut.Unlock()
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request.result <- result{nil, evictionTime}
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}
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}
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func evict(relay relay) func() {
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return func() {
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mut.Lock()
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defer mut.Unlock()
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if debug {
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log.Println("Evicting", relay)
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}
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for i, current := range knownRelays {
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if current == relay {
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if debug {
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log.Println("Evicted", relay)
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}
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last := len(knownRelays) - 1
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knownRelays[i] = knownRelays[last]
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knownRelays = knownRelays[:last]
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}
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}
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delete(evictionTimers, relay.URL)
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}
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}
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