open-consul/agent/pool/peek.go

83 lines
2.2 KiB
Go

// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package pool
import (
"bufio"
"fmt"
"net"
)
// PeekForTLS will read the first byte on the conn to determine if the client
// request is a TLS connection request or a consul-specific framed rpc request.
//
// This function does not close the conn on an error.
//
// The returned conn has the initial read buffered internally for the purposes
// of not consuming the first byte. After that buffer is drained the conn is a
// pass through to the original conn.
//
// The TLS record layer governs the very first byte. The available options start
// at 20 as per:
//
// - v1.2: https://tools.ietf.org/html/rfc5246#appendix-A.1
// - v1.3: https://tools.ietf.org/html/rfc8446#appendix-B.1
//
// Note: this indicates that '0' is 'invalid'. Given that we only care about
// the first byte of a long-lived connection this is irrelevant, since you must
// always start out with a client hello handshake which is '22'.
func PeekForTLS(conn net.Conn) (net.Conn, bool, error) {
br := bufio.NewReader(conn)
// Grab enough to read the first byte. Then drain the buffer so future
// reads can be direct.
peeked, err := br.Peek(1)
if err != nil {
return nil, false, err
} else if len(peeked) == 0 {
return conn, false, nil
}
peeked, err = br.Peek(br.Buffered())
if err != nil {
return nil, false, err
}
isTLS := (peeked[0] > RPCMaxTypeValue)
return &peekedConn{
Peeked: peeked,
Conn: conn,
}, isTLS, nil
}
// PeekFirstByte will read the first byte on the conn.
//
// This function does not close the conn on an error.
//
// The returned conn has the initial read buffered internally for the purposes
// of not consuming the first byte. After that buffer is drained the conn is a
// pass through to the original conn.
func PeekFirstByte(conn net.Conn) (net.Conn, byte, error) {
br := bufio.NewReader(conn)
// Grab enough to read the first byte. Then drain the buffer so future
// reads can be direct.
peeked, err := br.Peek(1)
if err != nil {
return nil, 0, err
} else if len(peeked) == 0 {
return conn, 0, fmt.Errorf("nothing to read")
}
peeked, err = br.Peek(br.Buffered())
if err != nil {
return nil, 0, err
}
return &peekedConn{
Peeked: peeked,
Conn: conn,
}, peeked[0], nil
}