move implementation to internal/ directory (#828)
This commit is contained in:
Christian Schwarz
committed by
GitHub
GitHub
parent
b9b9ad10cf
commit
908807bd59
@@ -0,0 +1,239 @@
|
||||
// Package versionhandshake wraps a transport.{Connecter,AuthenticatedListener}
|
||||
// to add an exchange of protocol version information on connection establishment.
|
||||
//
|
||||
// The protocol version information (banner) is plain text, thus making it
|
||||
// easy to diagnose issues with standard tools.
|
||||
package versionhandshake
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"io"
|
||||
"net"
|
||||
"strings"
|
||||
"time"
|
||||
"unicode/utf8"
|
||||
)
|
||||
|
||||
type HandshakeMessage struct {
|
||||
ProtocolVersion int
|
||||
Extensions []string
|
||||
}
|
||||
|
||||
// A HandshakeError describes what went wrong during the handshake.
|
||||
// It implements net.Error and is always temporary.
|
||||
type HandshakeError struct {
|
||||
msg string
|
||||
// If not nil, the underlying IO error that caused the handshake to fail.
|
||||
IOError error
|
||||
isAcceptError bool
|
||||
}
|
||||
|
||||
var _ net.Error = &HandshakeError{}
|
||||
|
||||
func (e HandshakeError) Error() string { return e.msg }
|
||||
|
||||
// When a net.Listener.Accept() returns an error, the server must
|
||||
// decide whether to retry calling Accept() or not.
|
||||
// On some platforms (e.g., Linux), Accept() can return errors
|
||||
// related to the specific protocol connection that was supposed
|
||||
// to be returned as asocket FD. Obviously, we want to ignore,
|
||||
// maybe log, those errors and retry Accept() immediately to
|
||||
// serve other connections.
|
||||
// But there are also conditions where we get Accept() errors because
|
||||
// the process has run out of file descriptors. In that case, retrying
|
||||
// won't help. We need to close some file descriptor to make progress.
|
||||
// Note that there could be lots of open file descriptors because we
|
||||
// have accepted, and not yet closed, lots of connections in the past.
|
||||
// And then, of course there can be errors where we just want
|
||||
// to return, e.g., if there's a programming error and we're getting
|
||||
// an EBADFD or whatever.
|
||||
//
|
||||
// So, the serve loops in net/http.Server.Serve() or gRPC's server.Serve()
|
||||
// must inspect the error and decide what to do.
|
||||
// The vehicle for this is the
|
||||
//
|
||||
// interface { Temporary() bool }
|
||||
//
|
||||
// Behavior in both of the aforementioned Serve() loops:
|
||||
//
|
||||
// - if the error doesn't implement the interface, stop serving and return
|
||||
// - `Temporary() == true`: retry with back-off
|
||||
// - `Temporary() == false`: stop serving and return
|
||||
//
|
||||
// So, to make this package's HandshakeListener work with these
|
||||
// Serve() loops, we return Temporary() == true if the handshake fails.
|
||||
// In the aforementioned categories, that's the case of a per-connection
|
||||
// protocol error.
|
||||
//
|
||||
// Note: the net.Error interface has deprecated the Temporary() method
|
||||
// in go.dev/issue/45729, but there is no replacement for users of .Accept().
|
||||
// Existing users of .Accept() continue to check for the interface.
|
||||
// So, we need to continue supporting Temporary() until there's a different
|
||||
// mechanism for serve loops to decide whether to retry or not.
|
||||
// The following mailing list post proposes to eliminate the retries
|
||||
// completely, but it seems like the effort has stalled.
|
||||
// https://groups.google.com/g/golang-nuts/c/-JcZzOkyqYI/m/xwaZzjCgAwAJ
|
||||
func (e HandshakeError) Temporary() bool {
|
||||
if e.isAcceptError {
|
||||
return true
|
||||
}
|
||||
te, ok := e.IOError.(interface{ Temporary() bool })
|
||||
return ok && te.Temporary()
|
||||
}
|
||||
|
||||
// If the underlying IOError was net.Error.Timeout(), Timeout() returns that value.
|
||||
// Otherwise false.
|
||||
func (e HandshakeError) Timeout() bool {
|
||||
if neterr, ok := e.IOError.(net.Error); ok {
|
||||
return neterr.Timeout()
|
||||
}
|
||||
return false
|
||||
}
|
||||
|
||||
func hsErr(msg string) *HandshakeError {
|
||||
return &HandshakeError{msg: msg}
|
||||
}
|
||||
|
||||
func hsIOErr(err error, format string, args ...interface{}) *HandshakeError {
|
||||
return &HandshakeError{IOError: err, msg: fmt.Sprintf(format, args...)}
|
||||
}
|
||||
|
||||
// MaxProtocolVersion is the maximum allowed protocol version.
|
||||
// This is a protocol constant, changing it may break the wire format.
|
||||
const MaxProtocolVersion = 9999
|
||||
|
||||
// Only returns *HandshakeError as error.
|
||||
func (m *HandshakeMessage) Encode() ([]byte, error) {
|
||||
if m.ProtocolVersion <= 0 || m.ProtocolVersion > MaxProtocolVersion {
|
||||
return nil, hsErr(fmt.Sprintf("protocol version must be in [1, %d]", MaxProtocolVersion))
|
||||
}
|
||||
if len(m.Extensions) >= MaxProtocolVersion {
|
||||
return nil, hsErr(fmt.Sprintf("protocol only supports [0, %d] extensions", MaxProtocolVersion))
|
||||
}
|
||||
// EXTENSIONS is a count of subsequent \n separated lines that contain protocol extensions
|
||||
var extensions strings.Builder
|
||||
for i, ext := range m.Extensions {
|
||||
if strings.ContainsAny(ext, "\n") {
|
||||
return nil, hsErr(fmt.Sprintf("Extension #%d contains forbidden newline character", i))
|
||||
}
|
||||
if !utf8.ValidString(ext) {
|
||||
return nil, hsErr(fmt.Sprintf("Extension #%d is not valid UTF-8", i))
|
||||
}
|
||||
extensions.WriteString(ext)
|
||||
extensions.WriteString("\n")
|
||||
}
|
||||
withoutLen := fmt.Sprintf("ZREPL_ZFS_REPLICATION PROTOVERSION=%04d EXTENSIONS=%04d\n%s",
|
||||
m.ProtocolVersion, len(m.Extensions), extensions.String())
|
||||
withLen := fmt.Sprintf("%010d %s", len(withoutLen), withoutLen)
|
||||
return []byte(withLen), nil
|
||||
}
|
||||
|
||||
func (m *HandshakeMessage) DecodeReader(r io.Reader, maxLen int) error {
|
||||
var lenAndSpace [11]byte
|
||||
if _, err := io.ReadFull(r, lenAndSpace[:]); err != nil {
|
||||
return hsIOErr(err, "error reading protocol banner length: %s", err)
|
||||
}
|
||||
if !utf8.Valid(lenAndSpace[:]) {
|
||||
return hsErr("invalid start of handshake message: not valid UTF-8")
|
||||
}
|
||||
var followLen int
|
||||
n, err := fmt.Sscanf(string(lenAndSpace[:]), "%010d ", &followLen)
|
||||
if n != 1 || err != nil {
|
||||
return hsErr("could not parse handshake message length")
|
||||
}
|
||||
if followLen > maxLen {
|
||||
return hsErr(fmt.Sprintf("handshake message length exceeds max length (%d vs %d)",
|
||||
followLen, maxLen))
|
||||
}
|
||||
|
||||
var buf bytes.Buffer
|
||||
_, err = io.Copy(&buf, io.LimitReader(r, int64(followLen)))
|
||||
if err != nil {
|
||||
return hsIOErr(err, "error reading protocol banner body: %s", err)
|
||||
}
|
||||
|
||||
var (
|
||||
protoVersion, extensionCount int
|
||||
)
|
||||
n, err = fmt.Fscanf(&buf, "ZREPL_ZFS_REPLICATION PROTOVERSION=%04d EXTENSIONS=%4d\n",
|
||||
&protoVersion, &extensionCount)
|
||||
if n != 2 || err != nil {
|
||||
return hsErr(fmt.Sprintf("could not parse handshake message: %s", err))
|
||||
}
|
||||
if protoVersion < 1 {
|
||||
return hsErr(fmt.Sprintf("invalid protocol version %q", protoVersion))
|
||||
}
|
||||
m.ProtocolVersion = protoVersion
|
||||
|
||||
if extensionCount < 0 {
|
||||
return hsErr(fmt.Sprintf("invalid extension count %q", extensionCount))
|
||||
}
|
||||
if extensionCount == 0 {
|
||||
if buf.Len() != 0 {
|
||||
return hsErr("unexpected data trailing after header")
|
||||
}
|
||||
m.Extensions = nil
|
||||
return nil
|
||||
}
|
||||
s := buf.String()
|
||||
if strings.Count(s, "\n") != extensionCount {
|
||||
return hsErr(fmt.Sprintf("inconsistent extension count: found %d, header says %d", len(m.Extensions), extensionCount))
|
||||
}
|
||||
exts := strings.Split(s, "\n")
|
||||
if exts[len(exts)-1] != "" {
|
||||
return hsErr("unexpected data trailing after last extension newline")
|
||||
}
|
||||
m.Extensions = exts[0 : len(exts)-1]
|
||||
|
||||
return nil
|
||||
}
|
||||
|
||||
func DoHandshakeCurrentVersion(conn net.Conn, deadline time.Time) *HandshakeError {
|
||||
// current protocol version is hardcoded here
|
||||
return DoHandshakeVersion(conn, deadline, 7)
|
||||
}
|
||||
|
||||
const HandshakeMessageMaxLen = 16 * 4096
|
||||
|
||||
func DoHandshakeVersion(conn net.Conn, deadline time.Time, version int) (rErr *HandshakeError) {
|
||||
ours := HandshakeMessage{
|
||||
ProtocolVersion: version,
|
||||
Extensions: nil,
|
||||
}
|
||||
hsb, err := ours.Encode()
|
||||
if err != nil {
|
||||
return hsErr(fmt.Sprintf("could not encode protocol banner: %s", err))
|
||||
}
|
||||
|
||||
err = conn.SetDeadline(deadline)
|
||||
if err != nil {
|
||||
return hsErr(fmt.Sprintf("could not set deadline for protocol banner handshake: %s", err))
|
||||
}
|
||||
defer func() {
|
||||
if rErr != nil {
|
||||
return
|
||||
}
|
||||
err := conn.SetDeadline(time.Time{})
|
||||
if err != nil {
|
||||
rErr = hsErr(fmt.Sprintf("could not reset deadline after protocol banner handshake: %s", err))
|
||||
}
|
||||
}()
|
||||
_, err = io.Copy(conn, bytes.NewBuffer(hsb))
|
||||
if err != nil {
|
||||
return hsErr(fmt.Sprintf("could not send protocol banner: %s", err))
|
||||
}
|
||||
|
||||
theirs := HandshakeMessage{}
|
||||
if err := theirs.DecodeReader(conn, HandshakeMessageMaxLen); err != nil {
|
||||
return hsErr(fmt.Sprintf("could not decode protocol banner: %s", err))
|
||||
}
|
||||
|
||||
if theirs.ProtocolVersion != ours.ProtocolVersion {
|
||||
return hsErr(fmt.Sprintf("protocol versions do not match: ours is %d, theirs is %d",
|
||||
ours.ProtocolVersion, theirs.ProtocolVersion))
|
||||
}
|
||||
// ignore extensions, we don't use them
|
||||
|
||||
return nil
|
||||
}
|
||||
Reference in New Issue
Block a user