/
service.go
300 lines (247 loc) · 5.42 KB
/
service.go
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package reseed
import (
"crypto/rsa"
"crypto/sha256"
"errors"
"fmt"
"hash/crc32"
"io/ioutil"
"log"
"math/rand"
"os"
"path/filepath"
"regexp"
"sync"
"time"
"i2p-tools/su3"
)
type routerInfo struct {
Name string
ModTime time.Time
Data []byte
}
type Peer string
func (p Peer) Hash() int {
b := sha256.Sum256([]byte(p))
c := make([]byte, len(b))
copy(c, b[:])
return int(crc32.ChecksumIEEE(c))
}
type Reseeder interface {
// get an su3 file (bytes) for a peer
PeerSu3Bytes(peer Peer) ([]byte, error)
}
type ReseederImpl struct {
netdb NetDbProvider
su3s chan [][]byte
SigningKey *rsa.PrivateKey
SignerID []byte
NumRi int
RebuildInterval time.Duration
NumSu3 int
}
func NewReseeder(netdb NetDbProvider) *ReseederImpl {
return &ReseederImpl{
netdb: netdb,
su3s: make(chan [][]byte),
NumRi: 77,
RebuildInterval: 90 * time.Hour,
}
}
func (rs *ReseederImpl) Start() chan bool {
// atomic swapper
go func() {
var m [][]byte
for {
select {
case m = <-rs.su3s:
case rs.su3s <- m:
}
}
}()
// init the cache
err := rs.rebuild()
if nil != err {
log.Println(err)
}
ticker := time.NewTicker(rs.RebuildInterval)
quit := make(chan bool)
go func() {
for {
select {
case <-ticker.C:
err := rs.rebuild()
if nil != err {
log.Println(err)
}
case <-quit:
ticker.Stop()
return
}
}
}()
return quit
}
func (rs *ReseederImpl) rebuild() error {
log.Println("Rebuilding su3 cache...")
// get all RIs from netdb provider
ris, err := rs.netdb.RouterInfos()
if nil != err {
return fmt.Errorf("Unable to get routerInfos: %s", err)
}
// use only 75% of routerInfos
ris = ris[len(ris)/4:]
// fail if we don't have enough RIs to make a single reseed file
if rs.NumRi > len(ris) {
return fmt.Errorf("not enough routerInfos - have: %d, need: %d", len(ris), rs.NumRi)
}
// build a pipeline ris -> seeds -> su3
seedsChan := rs.seedsProducer(ris)
// fan-in multiple builders
su3Chan := fanIn(rs.su3Builder(seedsChan), rs.su3Builder(seedsChan), rs.su3Builder(seedsChan))
// read from su3 chan and append to su3s slice
var newSu3s [][]byte
for gs := range su3Chan {
data, err := gs.MarshalBinary()
if nil != err {
return err
}
newSu3s = append(newSu3s, data)
}
// use this new set of su3s
rs.su3s <- newSu3s
log.Println("Done rebuilding.")
return nil
}
func (rs *ReseederImpl) seedsProducer(ris []routerInfo) <-chan []routerInfo {
lenRis := len(ris)
// if NumSu3 is not specified, then we determine the "best" number based on the number of RIs
var numSu3s int
if rs.NumSu3 != 0 {
numSu3s = rs.NumSu3
} else {
switch {
case lenRis > 4000:
numSu3s = 300
case lenRis > 3000:
numSu3s = 200
case lenRis > 2000:
numSu3s = 100
case lenRis > 1000:
numSu3s = 75
default:
numSu3s = 50
}
}
log.Printf("Building %d su3 files each containing %d out of %d routerInfos.\n", numSu3s, rs.NumRi, lenRis)
out := make(chan []routerInfo)
go func() {
for i := 0; i < numSu3s; i++ {
var seeds []routerInfo
unsorted := rand.Perm(lenRis)
for z := 0; z < rs.NumRi; z++ {
seeds = append(seeds, ris[unsorted[z]])
}
out <- seeds
}
close(out)
}()
return out
}
func (rs *ReseederImpl) su3Builder(in <-chan []routerInfo) <-chan *su3.File {
out := make(chan *su3.File)
go func() {
for seeds := range in {
gs, err := rs.createSu3(seeds)
if nil != err {
log.Println(err)
continue
}
out <- gs
}
close(out)
}()
return out
}
func (rs *ReseederImpl) PeerSu3Bytes(peer Peer) ([]byte, error) {
m := <-rs.su3s
defer func() { rs.su3s <- m }()
if 0 == len(m) {
return nil, errors.New("404")
}
return m[peer.Hash()%len(m)], nil
}
func (rs *ReseederImpl) createSu3(seeds []routerInfo) (*su3.File, error) {
su3File := su3.New()
su3File.FileType = su3.FileTypeZIP
su3File.ContentType = su3.ContentTypeReseed
zipped, err := zipSeeds(seeds)
if nil != err {
return nil, err
}
su3File.Content = zipped
su3File.SignerID = rs.SignerID
su3File.Sign(rs.SigningKey)
return su3File, nil
}
type NetDbProvider interface {
// Get all router infos
RouterInfos() ([]routerInfo, error)
}
type LocalNetDbImpl struct {
Path string
}
func NewLocalNetDb(path string) *LocalNetDbImpl {
return &LocalNetDbImpl{
Path: path,
}
}
func (db *LocalNetDbImpl) RouterInfos() (routerInfos []routerInfo, err error) {
r, _ := regexp.Compile("^routerInfo-[A-Za-z0-9-=~]+.dat$")
files := make(map[string]os.FileInfo)
walkpath := func(path string, f os.FileInfo, err error) error {
if r.MatchString(f.Name()) {
files[path] = f
}
return nil
}
filepath.Walk(db.Path, walkpath)
for path, file := range files {
riBytes, err := ioutil.ReadFile(path)
if nil != err {
log.Println(err)
continue
}
// ignore outdate routerInfos
age := time.Since(file.ModTime())
if age.Hours() > 192 {
continue
}
routerInfos = append(routerInfos, routerInfo{
Name: file.Name(),
ModTime: file.ModTime(),
Data: riBytes,
})
}
return
}
func fanIn(inputs ...<-chan *su3.File) <-chan *su3.File {
out := make(chan *su3.File, len(inputs))
var wg sync.WaitGroup
wg.Add(len(inputs))
go func() {
// close "out" when we're done
wg.Wait()
close(out)
}()
// fan-in all the inputs to a single output
for _, input := range inputs {
go func(in <-chan *su3.File) {
defer wg.Done()
for n := range in {
out <- n
}
}(input)
}
return out
}