p2p: use errors.Is for error comparison (ethereum#24882)

Co-authored-by: Felix Lange <fjl@twurst.com>

p2p/discover/lookup.go

@@ -18,6 +18,7 @@ package discover
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"github.com/ethereum/go-ethereum/p2p/enode"
@@ -141,7 +142,7 @@ func (it *lookup) slowdown() {
 func (it *lookup) query(n *node, reply chan<- []*node) {
 	fails := it.tab.db.FindFails(n.ID(), n.IP())
 	r, err := it.queryfunc(n)
-	if err == errClosed {
+	if errors.Is(err, errClosed) {
 		// Avoid recording failures on shutdown.
 		reply <- nil
 		return

p2p/discover/v4_udp.go

@@ -328,7 +328,7 @@ func (t *UDPv4) findnode(toid enode.ID, toaddr *net.UDPAddr, target v4wire.Pubke
 	// enough nodes the reply matcher will time out waiting for the second reply, but
 	// there's no need for an error in that case.
 	err := <-rm.errc
-	if err == errTimeout && rm.reply != nil {
+	if errors.Is(err, errTimeout) && rm.reply != nil {
 		err = nil
 	}
 	return nodes, err
@@ -526,7 +526,7 @@ func (t *UDPv4) readLoop(unhandled chan<- ReadPacket) {
 			continue
 		} else if err != nil {
 			// Shut down the loop for permament errors.
-			if err != io.EOF {
+			if !errors.Is(err, io.EOF) {
 				t.log.Debug("UDP read error", "err", err)
 			}
 			return

p2p/discover/v5_udp.go

@@ -305,7 +305,7 @@ func (t *UDPv5) lookupWorker(destNode *node, target enode.ID) ([]*node, error) {
 	)
 	var r []*enode.Node
 	r, err = t.findnode(unwrapNode(destNode), dists)
-	if err == errClosed {
+	if errors.Is(err, errClosed) {
 		return nil, err
 	}
 	for _, n := range r {
@@ -623,7 +623,7 @@ func (t *UDPv5) readLoop() {
 			continue
 		} else if err != nil {
 			// Shut down the loop for permament errors.
-			if err != io.EOF {
+			if !errors.Is(err, io.EOF) {
 				t.log.Debug("UDP read error", "err", err)
 			}
 			return

p2p/discover/v5wire/encoding.go

@@ -596,7 +596,7 @@ func (c *Codec) decodeMessage(fromAddr string, head *Header, headerData, msgData
 	// Try decrypting the message.
 	key := c.sc.readKey(auth.SrcID, fromAddr)
 	msg, err := c.decryptMessage(msgData, head.Nonce[:], headerData, key)
-	if err == errMessageDecrypt {
+	if errors.Is(err, errMessageDecrypt) {
 		// It didn't work. Start the handshake since this is an ordinary message packet.
 		return &Unknown{Nonce: head.Nonce}, nil
 	}

p2p/dnsdisc/client.go

@@ -19,6 +19,7 @@ package dnsdisc
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"math/rand"
 	"net"
@@ -204,7 +205,7 @@ func (c *Client) doResolveEntry(ctx context.Context, domain, hash string) (entry
 	}
 	for _, txt := range txts {
 		e, err := parseEntry(txt, c.cfg.ValidSchemes)
-		if err == errUnknownEntry {
+		if errors.Is(err, errUnknownEntry) {
 			continue
 		}
 		if !bytes.HasPrefix(crypto.Keccak256([]byte(txt)), wantHash) {
@@ -281,7 +282,7 @@ func (it *randomIterator) nextNode() *enode.Node {
 		}
 		n, err := ct.syncRandom(it.ctx)
 		if err != nil {
-			if err == it.ctx.Err() {
+			if errors.Is(err, it.ctx.Err()) {
 				return nil // context canceled.
 			}
 			it.c.cfg.Logger.Debug("Error in DNS random node sync", "tree", ct.loc.domain, "err", err)

p2p/enr/entries.go

@@ -17,6 +17,7 @@
 package enr
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -180,9 +181,16 @@ func (err *KeyError) Error() string {
 	return fmt.Sprintf("ENR key %q: %v", err.Key, err.Err)
 }
 
+func (err *KeyError) Unwrap() error {
+	return err.Err
+}
+
 // IsNotFound reports whether the given error means that a key/value pair is
 // missing from a record.
 func IsNotFound(err error) bool {
-	kerr, ok := err.(*KeyError)
-	return ok && kerr.Err == errNotFound
+	var ke *KeyError
+	if errors.As(err, &ke) {
+		return ke.Err == errNotFound
+	}
+	return false
 }

p2p/peer.go

@@ -416,7 +416,7 @@ func (p *Peer) startProtocols(writeStart <-chan struct{}, writeErr chan<- error)
 			if err == nil {
 				p.log.Trace(fmt.Sprintf("Protocol %s/%d returned", proto.Name, proto.Version))
 				err = errProtocolReturned
-			} else if err != io.EOF {
+			} else if !errors.Is(err, io.EOF) {
 				p.log.Trace(fmt.Sprintf("Protocol %s/%d failed", proto.Name, proto.Version), "err", err)
 			}
 			p.protoErr <- err

p2p/peer_error.go

@@ -103,7 +103,7 @@ func discReasonForError(err error) DiscReason {
 	if reason, ok := err.(DiscReason); ok {
 		return reason
 	}
-	if err == errProtocolReturned {
+	if errors.Is(err, errProtocolReturned) {
 		return DiscQuitting
 	}
 	peerError, ok := err.(*peerError)

p2p/simulations/http.go

@@ -21,6 +21,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"html"
 	"io"
@@ -559,7 +560,7 @@ func (s *Server) CreateNode(w http.ResponseWriter, req *http.Request) {
 	config := &adapters.NodeConfig{}
 
 	err := json.NewDecoder(req.Body).Decode(config)
-	if err != nil && err != io.EOF {
+	if err != nil && !errors.Is(err, io.EOF) {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}