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package main
import (
"crypto/sha256"
"encoding/hex"
"flag"
"fmt"
"io"
"log"
"net/http"
"sort"
"strings"
"sync"
)
var mu sync.Mutex
var me string
var hashToDomain map[string]string
var peerHashes []string
var kvstore map[string]string
func sha256sum(s string) string {
// Get the sha256sum of string as a hex string
b := sha256.Sum256([]byte(s))
return hex.EncodeToString(b[:])
}
func addPeer(peer string) error {
// Try to peer with another server
peerHash := sha256sum(peer)
// Check if already peered
mu.Lock()
_, ok := hashToDomain[peerHash]
mu.Unlock()
if ok {
return nil
}
mu.Lock()
hashToDomain[peerHash] = peer
mu.Unlock()
// Try request to peer
log.Printf("%s trying to peer with %s", me, peer)
resp, err := http.Get(peer + "/peer?peer=" + me)
if err != nil {
// Request failed, delete peer
mu.Lock()
delete(hashToDomain, peerHash)
mu.Unlock()
return err
}
log.Printf("%s successfully peered with %s", me, peer)
mu.Lock()
peerHashes = append(peerHashes, peerHash)
sort.Sort(sort.StringSlice(peerHashes))
mu.Unlock()
// Read response body
defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
return err
}
// Try adding all peers of this peer
newPeers := strings.Split(string(body), "\n")
for _, newPeer := range newPeers[:len(newPeers)-1] {
go addPeer(newPeer)
}
return nil
}
func peerHandler(w http.ResponseWriter, r *http.Request) {
// Handle incoming peer requests
r.ParseForm()
peer := r.Form.Get("peer")
if peer == "" {
w.WriteHeader(http.StatusBadRequest)
return
}
go addPeer(peer)
for _, p := range hashToDomain {
fmt.Fprintf(w, "%s\n", p)
}
}
func getHandler(w http.ResponseWriter, r *http.Request) {
}
func setHandler(w http.ResponseWriter, r *http.Request) {
}
func main() {
bindAddr := flag.String("b", ":4200", "bind address")
domain := flag.String("d", "http://localhost:4200", "full domain name")
peer := flag.String("i", "", "initial peer")
flag.Parse()
log.Printf("Starting %s %s %s", *bindAddr, *domain, *peer)
// Record myself
me = *domain
peerHashes = append(peerHashes, sha256sum(me))
hashToDomain = map[string]string{peerHashes[0]: me}
if *peer != "" {
go addPeer(*peer)
}
http.HandleFunc("/peer", peerHandler)
http.HandleFunc("/get", getHandler)
http.HandleFunc("/set", setHandler)
log.Fatal(http.ListenAndServe(*bindAddr, nil))
}
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