128 lines
3.6 KiB
Go
128 lines
3.6 KiB
Go
// Copyright 2021 The go-ethereum Authors
|
|
// This file is part of the go-ethereum library.
|
|
//
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public License
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
package rlpx
|
|
|
|
import (
|
|
"io"
|
|
)
|
|
|
|
// readBuffer implements buffering for network reads. This type is similar to bufio.Reader,
|
|
// with two crucial differences: the buffer slice is exposed, and the buffer keeps all
|
|
// read data available until reset.
|
|
//
|
|
// How to use this type:
|
|
//
|
|
// Keep a readBuffer b alongside the underlying network connection. When reading a packet
|
|
// from the connection, first call b.reset(). This empties b.data. Now perform reads
|
|
// through b.read() until the end of the packet is reached. The complete packet data is
|
|
// now available in b.data.
|
|
type readBuffer struct {
|
|
data []byte
|
|
end int
|
|
}
|
|
|
|
// reset removes all processed data which was read since the last call to reset.
|
|
// After reset, len(b.data) is zero.
|
|
func (b *readBuffer) reset() {
|
|
unprocessed := b.end - len(b.data)
|
|
copy(b.data[:unprocessed], b.data[len(b.data):b.end])
|
|
b.end = unprocessed
|
|
b.data = b.data[:0]
|
|
}
|
|
|
|
// read reads at least n bytes from r, returning the bytes.
|
|
// The returned slice is valid until the next call to reset.
|
|
func (b *readBuffer) read(r io.Reader, n int) ([]byte, error) {
|
|
offset := len(b.data)
|
|
have := b.end - len(b.data)
|
|
|
|
// If n bytes are available in the buffer, there is no need to read from r at all.
|
|
if have >= n {
|
|
b.data = b.data[:offset+n]
|
|
return b.data[offset : offset+n], nil
|
|
}
|
|
|
|
// Make buffer space available.
|
|
need := n - have
|
|
b.grow(need)
|
|
|
|
// Read.
|
|
rn, err := io.ReadAtLeast(r, b.data[b.end:cap(b.data)], need)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
b.end += rn
|
|
b.data = b.data[:offset+n]
|
|
return b.data[offset : offset+n], nil
|
|
}
|
|
|
|
// grow ensures the buffer has at least n bytes of unused space.
|
|
func (b *readBuffer) grow(n int) {
|
|
if cap(b.data)-b.end >= n {
|
|
return
|
|
}
|
|
need := n - (cap(b.data) - b.end)
|
|
offset := len(b.data)
|
|
b.data = append(b.data[:cap(b.data)], make([]byte, need)...)
|
|
b.data = b.data[:offset]
|
|
}
|
|
|
|
// writeBuffer implements buffering for network writes. This is essentially
|
|
// a convenience wrapper around a byte slice.
|
|
type writeBuffer struct {
|
|
data []byte
|
|
}
|
|
|
|
func (b *writeBuffer) reset() {
|
|
b.data = b.data[:0]
|
|
}
|
|
|
|
func (b *writeBuffer) appendZero(n int) []byte {
|
|
offset := len(b.data)
|
|
b.data = append(b.data, make([]byte, n)...)
|
|
return b.data[offset : offset+n]
|
|
}
|
|
|
|
func (b *writeBuffer) Write(data []byte) (int, error) {
|
|
b.data = append(b.data, data...)
|
|
return len(data), nil
|
|
}
|
|
|
|
const maxUint24 = int(^uint32(0) >> 8)
|
|
|
|
func readUint24(b []byte) uint32 {
|
|
return uint32(b[2]) | uint32(b[1])<<8 | uint32(b[0])<<16
|
|
}
|
|
|
|
func putUint24(v uint32, b []byte) {
|
|
b[0] = byte(v >> 16)
|
|
b[1] = byte(v >> 8)
|
|
b[2] = byte(v)
|
|
}
|
|
|
|
// growslice ensures b has the wanted length by either expanding it to its capacity
|
|
// or allocating a new slice if b has insufficient capacity.
|
|
func growslice(b []byte, wantLength int) []byte {
|
|
if len(b) >= wantLength {
|
|
return b
|
|
}
|
|
if cap(b) >= wantLength {
|
|
return b[:cap(b)]
|
|
}
|
|
return make([]byte, wantLength)
|
|
}
|