tracker/frontend/http/frontend.go
2018-09-11 17:17:09 -04:00

341 lines
8.7 KiB
Go

// Package http implements a BitTorrent frontend via the HTTP protocol as
// described in BEP 3 and BEP 23.
package http
import (
"context"
"crypto/tls"
"errors"
"net"
"net/http"
"time"
"github.com/julienschmidt/httprouter"
"github.com/chihaya/chihaya/bittorrent"
"github.com/chihaya/chihaya/frontend"
"github.com/chihaya/chihaya/pkg/log"
"github.com/chihaya/chihaya/pkg/stop"
)
// Config represents all of the configurable options for an HTTP BitTorrent
// Frontend.
type Config struct {
Addr string `yaml:"addr"`
HTTPSAddr string `yaml:"https_addr"`
ReadTimeout time.Duration `yaml:"read_timeout"`
WriteTimeout time.Duration `yaml:"write_timeout"`
IdleTimeout time.Duration `yaml:"idle_timeout"`
EnableKeepAlive bool `yaml:"enable_keepalive"`
TLSCertPath string `yaml:"tls_cert_path"`
TLSKeyPath string `yaml:"tls_key_path"`
EnableLegacyPHPURLs bool `yaml:"enable_legacy_php_urls"`
EnableRequestTiming bool `yaml:"enable_request_timing"`
ParseOptions `yaml:",inline"`
}
// LogFields renders the current config as a set of Logrus fields.
func (cfg Config) LogFields() log.Fields {
return log.Fields{
"addr": cfg.Addr,
"httpsAddr": cfg.HTTPSAddr,
"readTimeout": cfg.ReadTimeout,
"writeTimeout": cfg.WriteTimeout,
"idleTimeout": cfg.IdleTimeout,
"enableKeepAlive": cfg.EnableKeepAlive,
"tlsCertPath": cfg.TLSCertPath,
"tlsKeyPath": cfg.TLSKeyPath,
"enableLegacyPHPURLs": cfg.EnableLegacyPHPURLs,
"enableRequestTiming": cfg.EnableRequestTiming,
"allowIPSpoofing": cfg.AllowIPSpoofing,
"realIPHeader": cfg.RealIPHeader,
"maxNumWant": cfg.MaxNumWant,
"defaultNumWant": cfg.DefaultNumWant,
"maxScrapeInfoHashes": cfg.MaxScrapeInfoHashes,
}
}
// Default config constants.
const (
defaultReadTimeout = 2 * time.Second
defaultWriteTimeout = 2 * time.Second
defaultIdleTimeout = 30 * time.Second
)
// Validate sanity checks values set in a config and returns a new config with
// default values replacing anything that is invalid.
//
// This function warns to the logger when a value is changed.
func (cfg Config) Validate() Config {
validcfg := cfg
if cfg.ReadTimeout <= 0 {
validcfg.ReadTimeout = defaultReadTimeout
log.Warn("falling back to default configuration", log.Fields{
"name": "http.ReadTimeout",
"provided": cfg.ReadTimeout,
"default": validcfg.ReadTimeout,
})
}
if cfg.WriteTimeout <= 0 {
validcfg.WriteTimeout = defaultWriteTimeout
log.Warn("falling back to default configuration", log.Fields{
"name": "http.WriteTimeout",
"provided": cfg.WriteTimeout,
"default": validcfg.WriteTimeout,
})
}
if cfg.IdleTimeout <= 0 {
validcfg.IdleTimeout = defaultIdleTimeout
if cfg.EnableKeepAlive {
// If keepalive is disabled, this configuration isn't used anyway.
log.Warn("falling back to default configuration", log.Fields{
"name": "http.IdleTimeout",
"provided": cfg.IdleTimeout,
"default": validcfg.IdleTimeout,
})
}
}
return validcfg
}
// Frontend represents the state of an HTTP BitTorrent Frontend.
type Frontend struct {
srv *http.Server
tlsSrv *http.Server
tlsCfg *tls.Config
logic frontend.TrackerLogic
Config
}
// NewFrontend creates a new instance of an HTTP Frontend that asynchronously
// serves requests.
func NewFrontend(logic frontend.TrackerLogic, provided Config) (*Frontend, error) {
cfg := provided.Validate()
f := &Frontend{
logic: logic,
Config: cfg,
}
if cfg.Addr == "" && cfg.HTTPSAddr == "" {
return nil, errors.New("must specify addr or https_addr or both")
}
// If TLS is enabled, create a key pair.
if cfg.TLSCertPath != "" && cfg.TLSKeyPath != "" {
var err error
f.tlsCfg = &tls.Config{
Certificates: make([]tls.Certificate, 1),
}
f.tlsCfg.Certificates[0], err = tls.LoadX509KeyPair(cfg.TLSCertPath, cfg.TLSKeyPath)
if err != nil {
return nil, err
}
}
if cfg.HTTPSAddr != "" && f.tlsCfg == nil {
return nil, errors.New("must specify tls_cert_path and tls_key_path when using https_addr")
}
if cfg.HTTPSAddr == "" && f.tlsCfg != nil {
return nil, errors.New("must specify https_addr when using tls_cert_path and tls_key_path")
}
if cfg.Addr != "" {
go func() {
if err := f.listenAndServe(); err != nil {
log.Fatal("failed while serving http", log.Err(err))
}
}()
}
if cfg.HTTPSAddr != "" {
go func() {
if err := f.listenAndServeTLS(); err != nil {
log.Fatal("failed while serving https", log.Err(err))
}
}()
}
return f, nil
}
// Stop provides a thread-safe way to shutdown a currently running Frontend.
func (f *Frontend) Stop() stop.Result {
stopGroup := stop.NewGroup()
if f.srv != nil {
stopGroup.AddFunc(f.makeStopFunc(f.srv))
}
if f.tlsSrv != nil {
stopGroup.AddFunc(f.makeStopFunc(f.tlsSrv))
}
return stopGroup.Stop()
}
func (f *Frontend) makeStopFunc(stopSrv *http.Server) stop.Func {
return func() stop.Result {
c := make(stop.Channel)
go func() {
c.Done(stopSrv.Shutdown(context.Background()))
}()
return c.Result()
}
}
func (f *Frontend) handler() http.Handler {
router := httprouter.New()
router.GET("/announce", f.announceRoute)
router.GET("/scrape", f.scrapeRoute)
if f.EnableLegacyPHPURLs {
log.Info("http: enabling legacy PHP URLs")
router.GET("/announce.php", f.announceRoute)
router.GET("/scrape.php", f.scrapeRoute)
}
return router
}
// listenAndServe blocks while listening and serving non-TLS HTTP BitTorrent
// requests until Stop() is called or an error is returned.
func (f *Frontend) listenAndServe() error {
f.srv = &http.Server{
Addr: f.Addr,
Handler: f.handler(),
ReadTimeout: f.ReadTimeout,
WriteTimeout: f.WriteTimeout,
IdleTimeout: f.IdleTimeout,
}
f.srv.SetKeepAlivesEnabled(f.EnableKeepAlive)
// Start the HTTP server.
if err := f.srv.ListenAndServe(); err != http.ErrServerClosed {
return err
}
return nil
}
// listenAndServeTLS blocks while listening and serving TLS HTTP BitTorrent
// requests until Stop() is called or an error is returned.
func (f *Frontend) listenAndServeTLS() error {
f.tlsSrv = &http.Server{
Addr: f.HTTPSAddr,
TLSConfig: f.tlsCfg,
Handler: f.handler(),
ReadTimeout: f.ReadTimeout,
WriteTimeout: f.WriteTimeout,
}
// Disable KeepAlives.
f.tlsSrv.SetKeepAlivesEnabled(f.EnableKeepAlive)
// Start the HTTP server.
if err := f.tlsSrv.ListenAndServeTLS("", ""); err != http.ErrServerClosed {
return err
}
return nil
}
// announceRoute parses and responds to an Announce.
func (f *Frontend) announceRoute(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
var err error
var start time.Time
if f.EnableRequestTiming {
start = time.Now()
}
var af *bittorrent.AddressFamily
defer func() {
if f.EnableRequestTiming {
recordResponseDuration("announce", af, err, time.Since(start))
} else {
recordResponseDuration("announce", af, err, time.Duration(0))
}
}()
req, err := ParseAnnounce(r, f.ParseOptions)
if err != nil {
WriteError(w, err)
return
}
af = new(bittorrent.AddressFamily)
*af = req.IP.AddressFamily
ctx, resp, err := f.logic.HandleAnnounce(context.Background(), req)
if err != nil {
WriteError(w, err)
return
}
err = WriteAnnounceResponse(w, resp)
if err != nil {
WriteError(w, err)
return
}
go f.logic.AfterAnnounce(ctx, req, resp)
}
// scrapeRoute parses and responds to a Scrape.
func (f *Frontend) scrapeRoute(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
var err error
var start time.Time
if f.EnableRequestTiming {
start = time.Now()
}
var af *bittorrent.AddressFamily
defer func() {
if f.EnableRequestTiming {
recordResponseDuration("scrape", af, err, time.Since(start))
} else {
recordResponseDuration("scrape", af, err, time.Duration(0))
}
}()
req, err := ParseScrape(r, f.ParseOptions)
if err != nil {
WriteError(w, err)
return
}
host, _, err := net.SplitHostPort(r.RemoteAddr)
if err != nil {
log.Error("http: unable to determine remote address for scrape", log.Err(err))
WriteError(w, err)
return
}
reqIP := net.ParseIP(host)
if reqIP.To4() != nil {
req.AddressFamily = bittorrent.IPv4
} else if len(reqIP) == net.IPv6len { // implies reqIP.To4() == nil
req.AddressFamily = bittorrent.IPv6
} else {
log.Error("http: invalid IP: neither v4 nor v6", log.Fields{"RemoteAddr": r.RemoteAddr})
WriteError(w, bittorrent.ErrInvalidIP)
return
}
af = new(bittorrent.AddressFamily)
*af = req.AddressFamily
ctx, resp, err := f.logic.HandleScrape(context.Background(), req)
if err != nil {
WriteError(w, err)
return
}
err = WriteScrapeResponse(w, resp)
if err != nil {
WriteError(w, err)
return
}
go f.logic.AfterScrape(ctx, req, resp)
}