p2p: peerstore backed phonebook

network/p2p/peerstore/peerstore.go

@@ -18,15 +18,52 @@
 
 import (
 	"fmt"
+	"math"
+	"math/rand"
+	"time"
 
 	"github.com/libp2p/go-libp2p/core/peer"
 	libp2p "github.com/libp2p/go-libp2p/core/peerstore"
 	mempstore "github.com/libp2p/go-libp2p/p2p/host/peerstore/pstoremem"
+	"golang.org/x/exp/slices"
 )
 
+// when using GetAddresses with getAllAddresses, all the addresses will be retrieved, regardless
+// of how many addresses the phonebook actually has. ( with the retry-after logic applied )
+const getAllAddresses = math.MaxInt32
+
+// PhoneBookEntryRoles defines the roles that a single entry on the phonebook can take.
+// currently, we have two roles : relay role and archiver role, which are mutually exclusive.
+//
+//msgp:ignore PhoneBookEntryRoles
+type PhoneBookEntryRoles int
+
+const addressDataKey string = "addressData"
+
 // PeerStore implements Peerstore and CertifiedAddrBook.
 type PeerStore struct {
 	peerStoreCAB
+	connectionsRateLimitingCount  uint
+	connectionsRateLimitingWindow time.Duration
+}
+
+// addressData: holds the information associated with each phonebook address.
+type addressData struct {
+	// retryAfter is the time to wait before retrying to connect to the address.
+	retryAfter time.Time
+
+	// recentConnectionTimes is the log of connection times used to observe the maximum
+	// connections to the address in a given time window.
+	recentConnectionTimes []time.Time
+
+	// networkNames: lists the networks to which the given address belongs.
+	networkNames map[string]bool
+
+	// role is the role that this address serves.
+	role PhoneBookEntryRoles
+
+	// persistent is set true for peers whose record should not be removed for the peer list
+	persistent bool
 }
 
 // peerStoreCAB combines the libp2p Peerstore and CertifiedAddrBook interfaces.
@@ -47,6 +84,294 @@
 		info := addrInfo[i]
 		ps.AddAddrs(info.ID, info.Addrs, libp2p.AddressTTL)
 	}
-	pstore := &PeerStore{ps}
+	pstore := &PeerStore{peerStoreCAB: ps}
+	return pstore, nil
+}
+
+// MakePhonebook creates a phonebook with the passed configuration values
+func MakePhonebook(connectionsRateLimitingCount uint,
+	connectionsRateLimitingWindow time.Duration) (*PeerStore, error) {
+	ps, err := mempstore.NewPeerstore()
+	if err != nil {
+		return &PeerStore{}, fmt.Errorf("cannot initialize a peerstore: %w", err)
+	}
+	pstore := &PeerStore{peerStoreCAB: ps,
+		connectionsRateLimitingCount:  connectionsRateLimitingCount,
+		connectionsRateLimitingWindow: connectionsRateLimitingWindow,
+	}
 	return pstore, nil
 }
+
+// GetAddresses returns up to N addresses, but may return fewer
+func (ps *PeerStore) GetAddresses(n int, role PhoneBookEntryRoles) []string {
+	return shuffleSelect(ps.filterRetryTime(time.Now(), role), n)
+}
+
+// UpdateRetryAfter updates the retryAfter time for the given address.
+func (ps *PeerStore) UpdateRetryAfter(addr string, retryAfter time.Time) {
+	info, err := PeerInfoFromDomainPort(addr)
+	if err != nil {
+		return
+	}
+	metadata, _ := ps.Get(info.ID, addressDataKey)
+	if metadata != nil {
+		ad, ok := metadata.(addressData)
+		if !ok {
+			return
+		}
+		ad.retryAfter = retryAfter
+		_ = ps.Put(info.ID, addressDataKey, ad)
+	}
+
+}
+
+// GetConnectionWaitTime will calculate and return the wait
+// time to prevent exceeding connectionsRateLimitingCount.
+// The connection should be established when the waitTime is 0.
+// It will register a provisional next connection time when the waitTime is 0.
+// The provisional time should be updated after the connection with UpdateConnectionTime
+func (ps *PeerStore) GetConnectionWaitTime(addr string) (bool, time.Duration, time.Time) {
+	curTime := time.Now()
+	info, err := PeerInfoFromDomainPort(addr)
+	if err != nil {
+		return false, 0 /* not used */, curTime /* not used */
+	}
+	var timeSince time.Duration
+	var numElmtsToRemove int
+	metadata, err := ps.Get(info.ID, addressDataKey)
+	if err != nil {
+		return false, 0 /* not used */, curTime /* not used */
+	}
+	ad, ok := metadata.(addressData)
+	if !ok {
+		return false, 0 /* not used */, curTime /* not used */
+	}
+	// Remove from recentConnectionTimes the times later than ConnectionsRateLimitingWindowSeconds
+	for numElmtsToRemove < len(ad.recentConnectionTimes) {
+		timeSince = curTime.Sub(ad.recentConnectionTimes[numElmtsToRemove])
+		if timeSince >= ps.connectionsRateLimitingWindow {
+			numElmtsToRemove++
+		} else {
+			break // break the loop. The rest are earlier than 1 second
+		}
+	}
+
+	// Remove the expired elements from e.data[addr].recentConnectionTimes
+	ps.popNElements(numElmtsToRemove, peer.ID(addr))
+	// If there are max number of connections within the time window, wait
+	metadata, _ = ps.Get(info.ID, addressDataKey)
+	ad, ok = metadata.(addressData)
+	if !ok {
+		return false, 0 /* not used */, curTime /* not used */
+	}
+	numElts := len(ad.recentConnectionTimes)
+	if uint(numElts) >= ps.connectionsRateLimitingCount {
+		return true, /* true */
+			ps.connectionsRateLimitingWindow - timeSince, curTime /* not used */
+	}
+
+	// Else, there is space in connectionsRateLimitingCount. The
+	// connection request of the caller will proceed
+	// Update curTime, since it may have significantly changed if waited
+	provisionalTime := time.Now()
+	// Append the provisional time for the next connection request
+	ps.appendTime(info.ID, provisionalTime)
+	return true, 0 /* no wait. proceed */, provisionalTime
+}
+
+// UpdateConnectionTime updates the connection time for the given address.
+func (ps *PeerStore) UpdateConnectionTime(addr string, provisionalTime time.Time) bool {
+	info, err := PeerInfoFromDomainPort(addr)
+	if err != nil {
+		return false
+	}
+	metadata, err := ps.Get(info.ID, addressDataKey)
+	if err != nil {
+		return false
+	}
+	ad, ok := metadata.(addressData)
+	if !ok {
+		return false
+	}
+	defer func() {
+		_ = ps.Put(info.ID, addressDataKey, ad)
+
+	}()
+
+	// Find the provisionalTime and update it
+	entry := ad.recentConnectionTimes
+	for indx, val := range entry {
+		if provisionalTime == val {
+			entry[indx] = time.Now()
+			return true
+		}
+	}
+
+	// Case where the time is not found: it was removed from the list.
+	// This may happen when the time expires before the connection was established with the server.
+	// The time should be added again.
+	entry = append(entry, time.Now())
+	ad.recentConnectionTimes = entry
+
+	return true
+}
+
+// ReplacePeerList replaces the peer list for the given networkName and role.
+func (ps *PeerStore) ReplacePeerList(addressesThey []string, networkName string, role PhoneBookEntryRoles) {
+	// prepare a map of items we'd like to remove.
+	removeItems := make(map[peer.ID]bool, 0)
+	peerIDs := ps.Peers()
+	for _, pid := range peerIDs {
+		data, _ := ps.Get(pid, addressDataKey)
+		if data != nil {
+			ad := data.(addressData)
+			if ad.networkNames[networkName] && ad.role == role && !ad.persistent {
+				removeItems[pid] = true
+			}
+		}
+
+	}
+	for _, addr := range addressesThey {
+		info, err := PeerInfoFromDomainPort(addr)
+		if err != nil {
+			return
+		}
+		data, _ := ps.Get(info.ID, addressDataKey)
+		if data != nil {
+			// we already have this.
+			// Update the networkName
+			ad := data.(addressData)
+			ad.networkNames[networkName] = true
+
+			// do not remove this entry
+			delete(removeItems, info.ID)
+		} else {
+			// we don't have this item. add it.
+			ps.AddAddrs(info.ID, info.Addrs, libp2p.AddressTTL)
+			entry := makePhonebookEntryData(networkName, role, false)
+			_ = ps.Put(info.ID, addressDataKey, entry)
+		}
+	}
+
+	// remove items that were missing in addressesThey
+	for k := range removeItems {
+		ps.deletePhonebookEntry(k, networkName)
+	}
+}
+
+// AddPersistentPeers stores addresses of peers which are persistent.
+// i.e. they won't be replaced by ReplacePeerList calls
+func (ps *PeerStore) AddPersistentPeers(dnsAddresses []string, networkName string, role PhoneBookEntryRoles) {
+
+	for _, addr := range dnsAddresses {
+		info, err := PeerInfoFromDomainPort(addr)
+		if err != nil {
+			return
+		}
+		data, _ := ps.Get(info.ID, addressDataKey)
+		if data != nil {
+			// we already have this.
+			// Make sure the persistence field is set to true
+			ad := data.(addressData)
+			ad.persistent = true
+			_ = ps.Put(info.ID, addressDataKey, data)
+
+		} else {
+			// we don't have this item. add it.
+			ps.AddAddrs(info.ID, info.Addrs, libp2p.PermanentAddrTTL)
+			entry := makePhonebookEntryData(networkName, role, true)
+			_ = ps.Put(info.ID, addressDataKey, entry)
+		}
+	}
+}
+
+// Length returns the number of addrs in peerstore
+func (ps *PeerStore) Length() int {
+	return len(ps.Peers())
+}
+
+// makePhonebookEntryData creates a new address entry for provided network name and role.
+func makePhonebookEntryData(networkName string, role PhoneBookEntryRoles, persistent bool) addressData {
+	pbData := addressData{
+		networkNames:          make(map[string]bool),
+		recentConnectionTimes: make([]time.Time, 0),
+		role:                  role,
+		persistent:            persistent,
+	}
+	pbData.networkNames[networkName] = true
+	return pbData
+}
+
+func (ps *PeerStore) deletePhonebookEntry(peerID peer.ID, networkName string) {
+	data, err := ps.Get(peerID, addressDataKey)
+	if err != nil {
+		return
+	}
+	ad := data.(addressData)
+	delete(ad.networkNames, networkName)
+	if 0 == len(ad.networkNames) {
+		ps.ClearAddrs(peerID)
+		_ = ps.Put(peerID, addressDataKey, nil)
+	}
+}
+
+// AppendTime adds the current time to recentConnectionTimes in
+// addressData of addr
+func (ps *PeerStore) appendTime(peerID peer.ID, t time.Time) {
+	data, _ := ps.Get(peerID, addressDataKey)
+	ad := data.(addressData)
+	ad.recentConnectionTimes = append(ad.recentConnectionTimes, t)
+	_ = ps.Put(peerID, addressDataKey, ad)
+}
+
+// PopEarliestTime removes the earliest time from recentConnectionTimes in
+// addressData for addr
+// It is expected to be later than ConnectionsRateLimitingWindow
+func (ps *PeerStore) popNElements(n int, peerID peer.ID) {
+	data, _ := ps.Get(peerID, addressDataKey)
+	ad := data.(addressData)
+	ad.recentConnectionTimes = ad.recentConnectionTimes[n:]
+	_ = ps.Put(peerID, addressDataKey, ad)
+}
+
+func (ps *PeerStore) filterRetryTime(t time.Time, role PhoneBookEntryRoles) []string {
+	o := make([]string, 0, len(ps.Peers()))
+	for _, peerID := range ps.Peers() {
+		data, _ := ps.Get(peerID, addressDataKey)
+		if data != nil {
+			ad := data.(addressData)
+			if t.After(ad.retryAfter) && role == ad.role {
+				o = append(o, string(peerID))
+			}
+		}
+	}
+	return o
+}
+
+func shuffleSelect(set []string, n int) []string {
+	if n >= len(set) || n == getAllAddresses {
+		// return shuffled copy of everything
+		out := slices.Clone(set)
+		shuffleStrings(out)
+		return out
+	}
+	// Pick random indexes from the set
+	indexSample := make([]int, n)
+	for i := range indexSample {
+		indexSample[i] = rand.Intn(len(set)-i) + i
+		for oi, ois := range indexSample[:i] {
+			if ois == indexSample[i] {
+				indexSample[i] = oi
+			}
+		}
+	}
+	out := make([]string, n)
+	for i, index := range indexSample {
+		out[i] = set[index]
+	}
+	return out
+}
+
+func shuffleStrings(set []string) {
+	rand.Shuffle(len(set), func(i, j int) { set[i], set[j] = set[j], set[i] })
+}