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Finish DHT server and client implementation

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This commit is contained in:
Anthony Wang 2023-05-12 11:09:07 -04:00
parent cdd295e371
commit ae29c8b047
Signed by: a
GPG key ID: 42A5B952E6DD8D38
5 changed files with 174 additions and 70 deletions
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75
client/main.go
View file

@ -1,14 +1,30 @@
package main
import (
"bytes"
"crypto/ed25519"
"encoding/base64"
"flag"
"fmt"
"net/http"
"os"
"strings"
"time"
)
var pubKey ed25519.PublicKey
var privKey ed25519.PrivateKey
var id string
var servers []string
// Post new server list to DHT
func dhtPost(s string) {
message := []byte(fmt.Sprint(time.Now().Unix()) + "\n" + strings.Join(servers, "\n"))
fmt.Print(message)
message = append(message, ed25519.Sign(privKey, message)...)
http.Post(s+"/dht/"+id, "application/octet-stream", bytes.NewBuffer(message))
}
func main() {
flag.Parse()
@ -18,11 +34,11 @@ func main() {
if err != nil {
panic(err)
}
err = os.WriteFile("pubkey", pubKey, 644)
err = os.WriteFile("pubkey", pubKey, 0644)
if err != nil {
panic(err)
}
err = os.WriteFile("privkey", privKey, 600)
err = os.WriteFile("privkey", privKey, 0600)
if err != nil {
panic(err)
}
@ -31,7 +47,7 @@ func main() {
if err != nil {
panic(err)
}
fmt.Printf("Success! Your user ID: %s", base64.RawURLEncoding.EncodeToString(pubKey))
fmt.Printf("Success! Your user ID: %s\n", base64.RawURLEncoding.EncodeToString(pubKey))
return
}
@ -49,11 +65,56 @@ func main() {
if err != nil {
panic(err)
}
id = base64.RawURLEncoding.EncodeToString(pubKey)
servers := strings.Split(string(serversBytes), "\n")
fmt.Println(pubKey, privKey, servers)
if flag.Arg(0) == "associate" {
if flag.Arg(0) == "add" {
// Add server
servers = append(servers, flag.Arg(1))
dhtPost(flag.Arg(1))
http.Get(flag.Arg(1) + "/user/" + id)
if servers[0] != flag.Arg(1) {
http.Get(servers[0] + "/user/" + id)
}
err := os.WriteFile("servers", []byte(strings.Join(servers, "\n")), 0644)
if err != nil {
panic(err)
}
} else if flag.Arg(0) == "remove" {
// Remove server
for i := range servers {
if servers[i] == flag.Arg(1) {
servers = append(servers[:i], servers[i+1:]...)
break
}
}
if len(servers) > 0 {
dhtPost(servers[0])
http.Get(servers[0] + "/user/" + id)
} else {
dhtPost(flag.Arg(1))
}
http.Get(flag.Arg(1) + "/user/" + id)
err := os.WriteFile("servers", []byte(strings.Join(servers, "\n")), 0644)
if err != nil {
panic(err)
}
} else if flag.Arg(0) == "primary" {
// Make server a primary
for i := range servers {
if i > 0 && servers[i] == flag.Arg(1) {
servers[i] = servers[0]
servers[0] = flag.Arg(i)
dhtPost(flag.Arg(i))
http.Get(servers[0] + "/user/" + id)
http.Get(servers[i] + "/user/" + id)
break
}
}
err := os.WriteFile("servers", []byte(strings.Join(servers, "\n")), 0644)
if err != nil {
panic(err)
}
}
}

143
server/dht.go
View file

@ -5,7 +5,6 @@ import (
"crypto/ed25519"
"crypto/sha256"
"encoding/base64"
"errors"
"fmt"
"io"
"log"
@ -63,7 +62,16 @@ func addPeer(peer string) error {
peerHashes[i] = peerHash
myPos = sort.SearchStrings(peerHashes, me)
// TODO: redistribute keys
// Distribute keys to new server
for id, user := range users {
phase := time.Now().Unix() / 600
if keyPos(id + "\n" + fmt.Sprint(phase))-myPos < 5 {
go http.Post(peer+"/dht/"+id+"?phase="+fmt.Sprint(phase)+"&direct=true", "application/octet-stream", bytes.NewBuffer(user.dhtVal))
}
if keyPos(id + "\n" + fmt.Sprint(phase+1))-myPos < 5 {
go http.Post(peer+"/dht/"+id+"?phase="+fmt.Sprint(phase+1)+"&direct=true", "application/octet-stream", bytes.NewBuffer(user.dhtVal))
}
}
mu.Unlock()
// Read response body
@ -116,8 +124,22 @@ func timestamp(val []byte) int {
}
// Get the value for a key from the DHT
func dhtGet(key string) ([]byte, error) {
keyPos := keyPos(key)
func dhtGet(key, direct string) []byte {
phase := fmt.Sprint(time.Now().Unix() / 600)
keyPos := keyPos(key + "\n" + phase)
if direct != "" && keyPos-myPos < 5 {
// Directly read from kvstore
mu.Lock()
val, ok := kvstore[key+"\n"+phase]
mu.Unlock()
if !ok || verify(key, val) != nil {
return nil
}
return val
}
// Contact 5 servers that store this key-value pair
var mu sync.Mutex
var wg sync.WaitGroup
var latest []byte
for i := 0; i < 5 && i < len(peerHashes); i++ {
@ -137,30 +159,56 @@ func dhtGet(key string) ([]byte, error) {
if err != nil {
return
}
mu.Lock()
if latest == nil || timestamp(val) > timestamp(latest) {
latest = val
}
mu.Unlock()
}()
}
// Wait for all to finish or time out
wg.Wait()
if latest == nil {
return nil, errors.New("key not found in kvstore")
}
return latest, nil
return latest
}
// Post a key-value pair into the DHT
func dhtPost(key string, val []byte) error {
func dhtPost(key, phase, direct string, val []byte) error {
err := verify(key, val)
if err != nil {
return err
}
keyPos := keyPos(key)
if phase == "" {
phase = fmt.Sprint(time.Now().Unix() / 600)
}
user, ok := users[key]
if ok {
curPhase, err := strconv.Atoi(phase)
if err != nil {
return err
}
nextPhase := time.Now().Unix()/600 + 1
if int64(curPhase) < nextPhase && user.phase < nextPhase {
user.phase = nextPhase
go dhtPost(key, fmt.Sprint(nextPhase), "", val)
}
}
keyPos := keyPos(key + "\n" + phase)
if direct != "" && keyPos-myPos < 5 {
// Directly write to kvstore
mu.Lock()
curVal, ok := kvstore[key+"\n"+phase]
if !ok || timestamp(val) > timestamp(curVal) {
kvstore[key+"\n"+phase] = val
}
mu.Unlock()
return nil
}
// Contact 5 servers that store this key-value pair
for i := 0; i < 5 && i < len(peerHashes); i++ {
j := hashToDomain[peerHashes[(keyPos+i)%len(peerHashes)]]
go func() {
http.Post(j+"/dht/"+key+"?direct", "application/octet-stream", bytes.NewBuffer(val))
}()
go http.Post(j+"/dht/"+key+"?phase="+phase+"&direct=true", "application/octet-stream", bytes.NewBuffer(val))
}
return nil
}
@ -169,52 +217,16 @@ func dhtPost(key string, val []byte) error {
func dhtHandler(w http.ResponseWriter, r *http.Request) {
key := r.URL.Path[5:]
r.ParseForm()
if r.Form.Get("direct") != "" {
// Directly modify kvstore
if keyPos(key)-myPos >= 5 {
w.WriteHeader(http.StatusNotFound)
return
}
phase := time.Now().Unix()/600
if r.Method == "GET" {
mu.Lock()
val, ok := kvstore[key+"\n"+fmt.Sprint(phase)]
mu.Unlock()
if !ok || verify(key, val) != nil {
w.WriteHeader(http.StatusNotFound)
return
}
w.Write(val)
} else if r.Method == "POST" {
val, err := io.ReadAll(r.Body)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
mu.Lock()
// Update key for this phase and next one
kvstore[key+"\n"+fmt.Sprint(phase)] = val
kvstore[key+"\n"+fmt.Sprint(phase+1)] = val
mu.Unlock()
}
return
}
if r.Method == "GET" {
val, err := dhtGet(key)
if err != nil {
val := dhtGet(key, r.Form.Get("direct"))
if val == nil {
w.WriteHeader(http.StatusNotFound)
return
}
w.Write([]byte(val))
w.Write(val)
} else if r.Method == "POST" {
val, err := io.ReadAll(r.Body)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
err = dhtPost(key, val)
if err != nil {
if err != nil || dhtPost(key, r.Form.Get("phase"), r.Form.Get("direct"), val) != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
@ -235,7 +247,23 @@ func cleanPeers() {
i := sort.SearchStrings(peerHashes, sha256sum(peer))
peerHashes = append(peerHashes[:i], peerHashes[i+1:]...)
myPos = sort.SearchStrings(peerHashes, me)
// TODO: redistribute keys
// Distribute keys on this server to other servers
if len(peerHashes) >= 5 {
for id, user := range users {
phase := time.Now().Unix() / 600
kpos := keyPos(id + "\n" + fmt.Sprint(phase))
if kpos-i < 5 {
server := hashToDomain[peerHashes[(kpos+4)%len(peerHashes)]]
go http.Post(server+"/dht/"+id+"?phase="+fmt.Sprint(phase)+"&direct=true", "application/octet-stream", bytes.NewBuffer(user.dhtVal))
}
kpos = keyPos(id + "\n" + fmt.Sprint(phase+1))
if kpos-i < 5 {
server := hashToDomain[peerHashes[(kpos+4)%len(peerHashes)]]
go http.Post(server+"/dht/"+id+"?phase="+fmt.Sprint(phase+1)+"&direct=true", "application/octet-stream", bytes.NewBuffer(user.dhtVal))
}
}
}
mu.Unlock()
}
time.Sleep(5 * time.Second)
@ -261,9 +289,14 @@ func cleanKVStore() {
// Redistribute key-value pairs periodically
func redistributeKeys() {
for true {
mu.Lock()
for id, user := range users {
dhtPost(id, user.dhtVal)
nextPhase := time.Now().Unix()/600 + 1
if user.phase < nextPhase {
go dhtPost(id, fmt.Sprint(nextPhase), "", user.dhtVal)
}
}
mu.Unlock()
time.Sleep(time.Duration(rand.Intn(300)) * time.Second)
}
}

11
server/main.go
View file

@ -30,14 +30,23 @@ func main() {
peerHashes = append(peerHashes, sha256sum(me))
hashToDomain = map[string]string{peerHashes[0]: me}
// Start background functions
if initialPeer != "" {
go addPeer(initialPeer)
}
go cleanPeers()
go cleanKVStore()
go redistributeKeys()
// Load user data from disk
entries, _ := os.ReadDir(dataDir)
err := os.Mkdir(dataDir, 0755)
if err != nil {
log.Fatal(err)
}
entries, err := os.ReadDir(dataDir)
if err != nil {
log.Fatal(err)
}
for _, entry := range entries {
id := entry.Name()
reader, err := os.Open(dataDir + "/" + id + "/gob")

4
server/test.sh
View file

@ -1,10 +1,10 @@
#!/bin/bash
trap "kill 0" EXIT
go build
./server -b :4200 -d http://localhost:4200 &
./server -d 0 &
for i in $(seq 1 9)
do
sleep 0.1
./server -b :420$i -d http://localhost:420$i -i http://localhost:420$((i-1)) &
./server -d $i -b :420$i -u http://localhost:420$i -i http://localhost:420$((i-1)) &
done
wait

11
server/user.go
View file

@ -11,7 +11,8 @@ import (
)
type user struct {
dhtVal []byte
dhtVal []byte
phase int64
}
var users map[string]user
@ -47,8 +48,8 @@ func persist(id string) {
func userHandler(w http.ResponseWriter, r *http.Request) {
id := r.URL.Fragment[6:]
// Resolve ID to server list
val, err := dhtGet(id)
if err != nil || verify(id, val) != nil {
val := dhtGet(id, "")
if verify(id, val) != nil {
w.WriteHeader(http.StatusNotFound)
return
}
@ -57,7 +58,7 @@ func userHandler(w http.ResponseWriter, r *http.Request) {
if !strings.Contains(message, me) {
// Delete user if they are no longer associated with this server
delete(users, id)
err = os.RemoveAll(id)
err := os.RemoveAll(id)
if err != nil {
w.WriteHeader(http.StatusNotFound)
return
@ -73,7 +74,7 @@ func userHandler(w http.ResponseWriter, r *http.Request) {
users[id] = user{
dhtVal: val,
}
os.Mkdir(id, 755)
os.Mkdir(id, 0755)
persist(id)
}
}