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