297 lines
8.8 KiB
Go
297 lines
8.8 KiB
Go
package noise
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import (
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"context"
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"crypto/rand"
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"encoding/binary"
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"fmt"
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"hash"
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"os"
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"runtime/debug"
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"time"
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"github.com/libp2p/go-libp2p/core/crypto"
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"github.com/libp2p/go-libp2p/core/peer"
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"github.com/libp2p/go-libp2p/p2p/security/noise/pb"
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"github.com/flynn/noise"
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pool "github.com/libp2p/go-buffer-pool"
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"github.com/minio/sha256-simd"
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"google.golang.org/protobuf/proto"
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)
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//go:generate protoc --go_out=. --go_opt=Mpb/payload.proto=./pb pb/payload.proto
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// payloadSigPrefix is prepended to our Noise static key before signing with
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// our libp2p identity key.
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const payloadSigPrefix = "noise-libp2p-static-key:"
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type minioSHAFn struct{}
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func (h minioSHAFn) Hash() hash.Hash { return sha256.New() }
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func (h minioSHAFn) HashName() string { return "SHA256" }
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var shaHashFn noise.HashFunc = minioSHAFn{}
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// All noise session share a fixed cipher suite
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var cipherSuite = noise.NewCipherSuite(noise.DH25519, noise.CipherChaChaPoly, shaHashFn)
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// runHandshake exchanges handshake messages with the remote peer to establish
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// a noise-libp2p session. It blocks until the handshake completes or fails.
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func (s *secureSession) runHandshake(ctx context.Context) (err error) {
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defer func() {
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if rerr := recover(); rerr != nil {
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fmt.Fprintf(os.Stderr, "caught panic: %s\n%s\n", rerr, debug.Stack())
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err = fmt.Errorf("panic in Noise handshake: %s", rerr)
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}
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}()
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kp, err := noise.DH25519.GenerateKeypair(rand.Reader)
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if err != nil {
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return fmt.Errorf("error generating static keypair: %w", err)
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}
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cfg := noise.Config{
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CipherSuite: cipherSuite,
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Pattern: noise.HandshakeXX,
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Initiator: s.initiator,
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StaticKeypair: kp,
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Prologue: s.prologue,
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}
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hs, err := noise.NewHandshakeState(cfg)
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if err != nil {
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return fmt.Errorf("error initializing handshake state: %w", err)
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}
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// set a deadline to complete the handshake, if one has been supplied.
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// clear it after we're done.
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if deadline, ok := ctx.Deadline(); ok {
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if err := s.SetDeadline(deadline); err == nil {
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// schedule the deadline removal once we're done handshaking.
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defer s.SetDeadline(time.Time{})
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}
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}
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// We can re-use this buffer for all handshake messages.
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hbuf := pool.Get(2 << 10)
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defer pool.Put(hbuf)
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if s.initiator {
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// stage 0 //
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// Handshake Msg Len = len(DH ephemeral key)
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if err := s.sendHandshakeMessage(hs, nil, hbuf); err != nil {
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return fmt.Errorf("error sending handshake message: %w", err)
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}
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// stage 1 //
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plaintext, err := s.readHandshakeMessage(hs)
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if err != nil {
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return fmt.Errorf("error reading handshake message: %w", err)
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}
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rcvdEd, err := s.handleRemoteHandshakePayload(plaintext, hs.PeerStatic())
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if err != nil {
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return err
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}
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if s.initiatorEarlyDataHandler != nil {
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if err := s.initiatorEarlyDataHandler.Received(ctx, s.insecureConn, rcvdEd); err != nil {
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return err
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}
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}
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// stage 2 //
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// Handshake Msg Len = len(DHT static key) + MAC(static key is encrypted) + len(Payload) + MAC(payload is encrypted)
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var ed *pb.NoiseExtensions
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if s.initiatorEarlyDataHandler != nil {
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ed = s.initiatorEarlyDataHandler.Send(ctx, s.insecureConn, s.remoteID)
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}
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payload, err := s.generateHandshakePayload(kp, ed)
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if err != nil {
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return err
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}
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if err := s.sendHandshakeMessage(hs, payload, hbuf); err != nil {
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return fmt.Errorf("error sending handshake message: %w", err)
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}
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return nil
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} else {
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// stage 0 //
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if _, err := s.readHandshakeMessage(hs); err != nil {
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return fmt.Errorf("error reading handshake message: %w", err)
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}
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// stage 1 //
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// Handshake Msg Len = len(DH ephemeral key) + len(DHT static key) + MAC(static key is encrypted) + len(Payload) +
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// MAC(payload is encrypted)
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var ed *pb.NoiseExtensions
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if s.responderEarlyDataHandler != nil {
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ed = s.responderEarlyDataHandler.Send(ctx, s.insecureConn, s.remoteID)
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}
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payload, err := s.generateHandshakePayload(kp, ed)
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if err != nil {
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return err
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}
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if err := s.sendHandshakeMessage(hs, payload, hbuf); err != nil {
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return fmt.Errorf("error sending handshake message: %w", err)
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}
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// stage 2 //
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plaintext, err := s.readHandshakeMessage(hs)
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if err != nil {
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return fmt.Errorf("error reading handshake message: %w", err)
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}
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rcvdEd, err := s.handleRemoteHandshakePayload(plaintext, hs.PeerStatic())
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if err != nil {
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return err
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}
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if s.responderEarlyDataHandler != nil {
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if err := s.responderEarlyDataHandler.Received(ctx, s.insecureConn, rcvdEd); err != nil {
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return err
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}
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}
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return nil
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}
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}
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// setCipherStates sets the initial cipher states that will be used to protect
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// traffic after the handshake.
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//
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// It is called when the final handshake message is processed by
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// either sendHandshakeMessage or readHandshakeMessage.
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func (s *secureSession) setCipherStates(cs1, cs2 *noise.CipherState) {
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if s.initiator {
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s.enc = cs1
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s.dec = cs2
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} else {
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s.enc = cs2
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s.dec = cs1
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}
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}
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// sendHandshakeMessage sends the next handshake message in the sequence.
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//
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// If payload is non-empty, it will be included in the handshake message.
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// If this is the final message in the sequence, calls setCipherStates
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// to initialize cipher states.
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func (s *secureSession) sendHandshakeMessage(hs *noise.HandshakeState, payload []byte, hbuf []byte) error {
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// the first two bytes will be the length of the noise handshake message.
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bz, cs1, cs2, err := hs.WriteMessage(hbuf[:LengthPrefixLength], payload)
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if err != nil {
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return err
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}
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// bz will also include the length prefix as we passed a slice of LengthPrefixLength length
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// to hs.Write().
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binary.BigEndian.PutUint16(bz, uint16(len(bz)-LengthPrefixLength))
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_, err = s.writeMsgInsecure(bz)
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if err != nil {
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return err
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}
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if cs1 != nil && cs2 != nil {
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s.setCipherStates(cs1, cs2)
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}
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return nil
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}
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// readHandshakeMessage reads a message from the insecure conn and tries to
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// process it as the expected next message in the handshake sequence.
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//
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// If the message contains a payload, it will be decrypted and returned.
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//
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// If this is the final message in the sequence, it calls setCipherStates
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// to initialize cipher states.
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func (s *secureSession) readHandshakeMessage(hs *noise.HandshakeState) ([]byte, error) {
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l, err := s.readNextInsecureMsgLen()
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if err != nil {
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return nil, err
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}
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buf := pool.Get(l)
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defer pool.Put(buf)
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if err := s.readNextMsgInsecure(buf); err != nil {
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return nil, err
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}
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msg, cs1, cs2, err := hs.ReadMessage(nil, buf)
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if err != nil {
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return nil, err
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}
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if cs1 != nil && cs2 != nil {
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s.setCipherStates(cs1, cs2)
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}
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return msg, nil
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}
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// generateHandshakePayload creates a libp2p handshake payload with a
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// signature of our static noise key.
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func (s *secureSession) generateHandshakePayload(localStatic noise.DHKey, ext *pb.NoiseExtensions) ([]byte, error) {
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// obtain the public key from the handshake session, so we can sign it with
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// our libp2p secret key.
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localKeyRaw, err := crypto.MarshalPublicKey(s.LocalPublicKey())
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if err != nil {
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return nil, fmt.Errorf("error serializing libp2p identity key: %w", err)
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}
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// prepare payload to sign; perform signature.
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toSign := append([]byte(payloadSigPrefix), localStatic.Public...)
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signedPayload, err := s.localKey.Sign(toSign)
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if err != nil {
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return nil, fmt.Errorf("error sigining handshake payload: %w", err)
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}
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// create payload
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payloadEnc, err := proto.Marshal(&pb.NoiseHandshakePayload{
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IdentityKey: localKeyRaw,
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IdentitySig: signedPayload,
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Extensions: ext,
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})
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if err != nil {
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return nil, fmt.Errorf("error marshaling handshake payload: %w", err)
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}
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return payloadEnc, nil
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}
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// handleRemoteHandshakePayload unmarshals the handshake payload object sent
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// by the remote peer and validates the signature against the peer's static Noise key.
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// It returns the data attached to the payload.
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func (s *secureSession) handleRemoteHandshakePayload(payload []byte, remoteStatic []byte) (*pb.NoiseExtensions, error) {
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// unmarshal payload
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nhp := new(pb.NoiseHandshakePayload)
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err := proto.Unmarshal(payload, nhp)
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if err != nil {
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return nil, fmt.Errorf("error unmarshaling remote handshake payload: %w", err)
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}
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// unpack remote peer's public libp2p key
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remotePubKey, err := crypto.UnmarshalPublicKey(nhp.GetIdentityKey())
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if err != nil {
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return nil, err
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}
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id, err := peer.IDFromPublicKey(remotePubKey)
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if err != nil {
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return nil, err
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}
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// check the peer ID if enabled
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if s.checkPeerID && s.remoteID != id {
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return nil, fmt.Errorf("peer id mismatch: expected %s, but remote key matches %s", s.remoteID.Pretty(), id.Pretty())
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}
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// verify payload is signed by asserted remote libp2p key.
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sig := nhp.GetIdentitySig()
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msg := append([]byte(payloadSigPrefix), remoteStatic...)
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ok, err := remotePubKey.Verify(msg, sig)
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if err != nil {
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return nil, fmt.Errorf("error verifying signature: %w", err)
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} else if !ok {
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return nil, fmt.Errorf("handshake signature invalid")
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}
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// set remote peer key and id
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s.remoteID = id
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s.remoteKey = remotePubKey
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return nhp.Extensions, nil
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}
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